bull Carbon monoxide CObull Sulfur dioxide SO2 bull Nitrogen oxidesbull Ozone O3 bull Particulates (PM10 and now PM25
bull Leadbull Volatile organic compounds (VOCs)
Carbon monoxide is generated when four variables are not kept sufficiently high1 Oxygen supply2 Combustion temperature3 Gas residence time at high temperature4 Combustion chamber turbulence
Unconventional Pollutantsbull Less abundant than conventional pollutants but very
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
bull Carbon monoxide CObull Sulfur dioxide SO2 bull Nitrogen oxidesbull Ozone O3 bull Particulates (PM10 and now PM25
bull Leadbull Volatile organic compounds (VOCs)
Carbon monoxide is generated when four variables are not kept sufficiently high1 Oxygen supply2 Combustion temperature3 Gas residence time at high temperature4 Combustion chamber turbulence
Unconventional Pollutantsbull Less abundant than conventional pollutants but very
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
bull Carbon monoxide CObull Sulfur dioxide SO2 bull Nitrogen oxidesbull Ozone O3 bull Particulates (PM10 and now PM25
bull Leadbull Volatile organic compounds (VOCs)
Carbon monoxide is generated when four variables are not kept sufficiently high1 Oxygen supply2 Combustion temperature3 Gas residence time at high temperature4 Combustion chamber turbulence
Unconventional Pollutantsbull Less abundant than conventional pollutants but very
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
bull Carbon monoxide CObull Sulfur dioxide SO2 bull Nitrogen oxidesbull Ozone O3 bull Particulates (PM10 and now PM25
bull Leadbull Volatile organic compounds (VOCs)
Carbon monoxide is generated when four variables are not kept sufficiently high1 Oxygen supply2 Combustion temperature3 Gas residence time at high temperature4 Combustion chamber turbulence
Unconventional Pollutantsbull Less abundant than conventional pollutants but very
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
bull Carbon monoxide CObull Sulfur dioxide SO2 bull Nitrogen oxidesbull Ozone O3 bull Particulates (PM10 and now PM25
bull Leadbull Volatile organic compounds (VOCs)
Carbon monoxide is generated when four variables are not kept sufficiently high1 Oxygen supply2 Combustion temperature3 Gas residence time at high temperature4 Combustion chamber turbulence
Unconventional Pollutantsbull Less abundant than conventional pollutants but very
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Conventional ldquoCriteriardquo Pollutants
bull Carbon monoxide CObull Sulfur dioxide SO2 bull Nitrogen oxidesbull Ozone O3 bull Particulates (PM10 and now PM25
bull Leadbull Volatile organic compounds (VOCs)
Carbon monoxide is generated when four variables are not kept sufficiently high1 Oxygen supply2 Combustion temperature3 Gas residence time at high temperature4 Combustion chamber turbulence
Unconventional Pollutantsbull Less abundant than conventional pollutants but very
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Photochemical smogbull Secondary pollutants
produced in presence of light (esp UV)ndash Ozone ndash nitrous oxide ndash nitric acid ndash ldquoothersrdquo
VOCs + Nox + Sunlight Photochemical smog
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Photochemical smog
Ref Introduction to environmental engineering and science by G M Masters amp W P Ela
Important key to understanding atmospheric organic chemistry is the hydroxyl radical which is formed when atomic oxygen reacts with waterO + H2O OH
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Variation of NO NO2 and O3 concentration
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Causes of outdoor air pollution in India
bull Exponential growth of vehicles outdated vehicle technology bad fuel quality poor maintenance of vehicles poor traffic management and planning
bull Unwillingness on the part of vehicle owners and the auto industry to accept emission norms
bull Lack of efficient public transport
bull Trucks and buses run on diesel which has high sulphur content
bull Old engines emit vast quantities of suspended particulate matter (SPM)
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Impact of air pollution
Air pollution
Health impacts
Headaches dizziness
Carbon monoxide
VOCs suspended particles
Lung cancer
Respiratory diseases
Asthma
Bronchitis
Influenza colds
SO2 NO2 NO
Impact on materials
Cars Homes
Monuments sites
Impact on plants
Reduced plant
growth
Damage to leaves of
crop plants
Susceptible to diseases pests frost
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
CASE STUDY-1
Bhopal gas tragedy (1984)
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The story of juvenile asthma
bull Many asthmatics among poor children in Indian cities
bull WHO estimate 10-15 of Indian children in the 5-11 age group suffer from asthma
bull Strong link between air pollution and asthmaStory of Kanpur one of the most polluted cities in India
Kanpur is home to many textile mills and leather units
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Mechanism of depletion of ozone layer and absorption of UV radiation
Molecular vibration and absorption of Infrared (IR) radiation
Climate change Global warming green house effect
Goal
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Mechanism of depletion of ozone layer and absorption of UV radiation
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Mechanism of depletion of ozone layer and ultraviolet ray absorption
httpswwwyoutubecomwatchv=k2kpz_8ntJY
Much like sunscreen for the Earth the ozone layer shields the Earth from the sunrsquos damaging UV-B radiation which can adversely affect human health and ecosystems
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The Chapman CycleThe stratosphere is in a constant cycle with oxygen molecules and their interaction with ultraviolet rays This process is considered a cycle because of its constant conversion between different molecules of oxygen The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O) This process is called the Chapman cycle
1An oxygen molecules is photolyzed by solar radiation creating two oxygen radicals
hν+O 2 rarr2O 2Oxygen radicals then react with molecular oxygen to produce ozone
O 2 +O rarrO 3 3Ozone then reacts with an additional oxygen radical to form molecular oxygen
O 3 +O rarr2O 2 4Ozone can also be recycled into molecular oxygen by reacting with a photon
O 3 +hνrarrO 2 +O
It is important to keep in mind that ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes which have been taking place for millions of years Because of this the thickness the ozone layer at any particular time can vary greatly It is also important to know that O2 is constantly being introduced into the atmosphere through photosynthesis so the ozone layer has the capability of regenerating itself
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Chemistry of Ozone DepletionCFC molecules are made up of chlorine fluorine and carbon atoms and are extremely stable This extreme stability allows CFCs to slowly make their way into the stratosphere (most molecules decompose before they can cross into the stratosphere from the troposphere) This prolonged life in the atmosphere allows them to reach great altitudes where photons are more energetic When the CFCs come into contact with these high energy photons their individual components are freed from the whole The following reaction displays how Cl atoms have an ozone destroying cycle
Cl+O 3 rarrClO+O 2 (step 1)
ClO+O rarrCl+O 2 (step 2)
O 3 +O rarr2O 2 (Overall reaction) Chlorine is able to destroy so much of the ozone because it acts as a catalyst Chlorine initiates the breakdown of ozone and combines with a freed oxygen to create two oxygen molecules After each reaction chlorine begins the destructive cycle again with another ozone molecule One chlorine atom can thereby destroy thousands of ozone molecules Because ozone molecules are being broken down they are unable to absorb any ultraviolet light so we experience more intense UV radiation at the earths surface
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Chemistry in Environmental Science
Photolysis of ozonehellip
What maximum wavelength of light would be capable of causing photolysis of ozone into oxygen and oxygen radical
ΔH0O3=1429kJmol
ΔH0O=2475kJmol
ΔH0O2=0kJmol
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Molecular vibration and IR absorption httpswwwyoutubecomwatchv=3szR-xQF4CA
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What is climate change
Global warming ndash doesnrsquot mean wersquoll all just have warmer weather in future
As the planet heats climate patterns change Itrsquoll mean more extreme and unpredictable weather across the world ndash many places will be hotter some wetter others drier
We know the planet has warmed by an average of nearly 1degC in the past century That might not sound much but on a global scale itrsquos a huge increase and itrsquos creating big problems for people and wildlife
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
httpswwwyoutubecomwatchv=52KLGqDSAjo
Climate Change -- the scientific debate
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
This is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming A Quick PollIs global warming real a) Yesb) No
How much has the average temperature of the Earth risen in the last 100 years
c) ~ 05degCd) ~ 10degC e) ~ 50degC f) ~ 100degC
As far as we know this is the highest temperature ever recorded in Earthrsquos history
g) Yesh) No
Who is to blamea) Human activitiesb) Nature causesc) ETd) NoCanTell
What is to blamee) Ozone f) CO2
g) H2Oh) O2
i) NoCanTell It is real complicated
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
1 Explain the impact of the greenhouse effect on planet Earth
2 Describe greenhouse gases and their effects3 Explain how human activities have
contributed to global warming 4 Describe the effects of global warming on
people and the land5 Give examples of what people can do about
the amount of greenhouse gases in the atmosphere
OBJECTIVES
>
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global WarmingWhat is it
Earth has warmed by about 1 ordm C over the past 100 years But why And How
Scientists are not exactly sure
The earth could be getting warm on itrsquos own
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
However hellipbull Many of the worldrsquos leading climate scientists think that things people do are helping to make the Earth warmer
bull Scientists are sure about the greenhouse effect They know that greenhouse gases make the earth warmer by trapping energy in the atmosphere
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What is the Greenhouse effectbull The greenhouse effect is the rise in temperature
that the Earth experiences because certain gases in the atmosphere trap heat from the Sunrsquos rays
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Have you seen a greenhouse
bull Most greenhouses look like small glasshouses
bull Green houses are used to grow plants especially in the winter
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
How do greenhouses work
bull Greenhouses work by trapping heat from the sun
bull The glass panels of the greenhouse let in light but keep heat from escaping
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
How do greenhouses work
bull This causes the greenhouse to heat up much like the inside of a car parked in sunlight and keeps the plants warm enough to live in the winter
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The Greenhouse Effect
bull The Earthrsquos atmosphere is all around us It is the air we breathe
bull Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The Greenhouse Effectbull Sunshine enters the Earthrsquos atmosphere passing through the blanket of greenhouse gasesbull As it reaches the Earthrsquos surface land water and biosphere absorb the sunlightrsquos energy Once absorbed this energy is sent back into the atmosphere
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
How do greenhouses work
bull Some of the energy passes back into space
bull Much of it remains trapped in the atmosphere by the greenhouse gases causing our world to heat up
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The greenhouse effect is important
bull Without the greenhouse effect the Earth would not be warm enough for humans to live
bull But if the greenhouse effect becomes stronger it could make the Earth warmer than usual
bull Even a little warming causes problems for plants and animals
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Greenhouse Effect
bull Without these gases heat would escape back into space and Earthrsquos average temperature would be about 60 ordm F colder
bull Because of how they warm our world these gases are referred to as greenhouse gases
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What are these gases
bull The greenhouse gases are
Water VapourCarbon dioxideNitrous OxideMethaneCFCs
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Water Vapour
bull There is more water in the atmosphere than carbon dioxide so most of the greenhouse heating of the Earthrsquos surface is due to water vapour
bull The water vapour content in the atmosphere is constant which means it hasnrsquot changed
>
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Water Vapourbull Water vapour is the biggest contributor to the
ldquonatural greenhouse effectrdquobull Human activities have little impact on the level of
water vapour
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Carbon Dioxide
bull Our atmosphere contains many natural gases other than ozone One of these natural gases is carbon dioxide
bull Our atmosphere needs a certain amount of this gas It is carbon dioxide that helps to keep the Earth warm
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Carbon Dioxidebull This gas holds in just enough heat from the sun to keep animals and plants alivebull If it held in more heat than it does the climate on Earth would grow too hot for some kinds of lifebull If it held in less heat Earthrsquos climate would be too cold
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Carbon Dioxide
bull Carbon Dioxide is probably the most important of the greenhouse gases and is currently responsible for 60 of the lsquoenhanced greenhouse effectrsquo
bull EnhancedHuman activities not natural
Global carbon dioxide emissions
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Carbon Dioxidebull For the past 100 years
the amount of carbon dioxide in our atmosphere seems to have been increasing
bull Why is this happening
bull What is it doing to the Earthrsquos atmosphere
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Where do all the carbon dioxide gases come from
bull Carbon dioxide Human respiration Industrialization Burning of fossil fuel to generate electricity Burning of forest (lesser trees) CO2 is now 13 more than before Industrial
Revolution
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Carbon Dioxide
bull Burning fossil fuels release the carbon dioxide stored millions of years ago
bull We use fossil fuels to run vehicles (petrol diesel and kerosene) heat homes businesses and power factories
>
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Nitrous Oxidebull Nitrous oxide makes up an extremely small amount of the atmosphere ndash It is less than one-thousandth as abundant as carbon dioxide
bull However it is 200 to 300 times more effective in trapping heat than carbon dioxide
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Nitrous Oxidebull Nitrous Oxide has one of the longest atmosphere
lifetimes of the greenhouse gases lasting for up to 150 years
bull Since the Industrial Revolution the level of nitrous oxide in the atmosphere has increased by 16
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Nitrous Oxide
bull The impact of human activities
Burning fossil fuels and wood
Widespread use of fertilizers
Sewage treatment plants
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Where do all nitrous oxide gases come from
bull Nitrous Oxide Vehicle exhaust Nitrogen based fertilisers
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Methane
bull The importance of methane in the greenhouse effect is itrsquos warming effect
bull It occurs in lower concentrations than carbon dioxide but it produces 21 times as much warming as carbon dioxide
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Methane
bull Methane accounts for 20of the lsquoenhanced greenhouse effectrsquo
bull It remains in the atmosphere for 10-12 years (Less than other greenhouse gases)
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Methanebull Human Activities
ndash An increase in livestock farming and rice growing has led to an increase in atmospheric methane Other sources are the extraction of fossil fuels landfill sites and the burning of biomass
ndash Methane concentration in the atmosphere has more than doubled during the last 200 yr Some of this methane is produced by ricefields
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Where do all the methane gases come from
bull Methane Produced by bacteria living in swampy areas
bull Wet rice cultivation Waste in landfills Rearing of livestock
bull When cows belch (burp) Each molecule can trap 20 times as much
heat as a CO2 molecule
>
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Where do all the CFCs come from
bull CFCs (Chlorofluorocarbons) Aerosol sprays Making foam packaging Coolants in fridge and air cons Cleaning solvents Each CFC molecule can trap as much heat as
100 000 CO2 molecule Can remain in the atmosphere for a long time
(up to 20 000 years)
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming
bull The average global temperature has increased by almost 1ordm C over the past century
bull Scientists expect the average global temperature to increase an additional 2ordm to 6ordm C over the next hundred years
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming
bull At the peak of the last ice age (18 000 years ago) the temperature was only 7 ordm colder than it is today and glaciers covered much of North America
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warmingbull Even a small increase in temperature over a long time
can change the climate
bull When the climate changes there may be big changes in the things that people depend on
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming
bull These things include the level of the oceans and the places where we plant crops They also include the air we breathe and the water we drink
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming
bull It is important to understand that scientists donrsquot know for sure what global warming will bring
bull Some changes may be goodEg If you live in a very cool climate warmer temperatures
might be welcome
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming
bull Days and nights would be more comfortable and people in the area may be able to grow different and better crops than they could before
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Global Warming
bull Changes in some places will not be good at allHuman HealthEcological Systems
(Plants and animals)Sea Level RiseCrops and Food Supply
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Human Healthbull Heat stress and other heat related health problems
are caused directly by very warm temperatures and high humidity
bull Heat stress ndash A variety of problems associated with very warm temperatures and high humidity eg Heat exhaustion and heat stroke
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ecological Systemsbull Plants and animals
Climate change may alter the worldrsquos habitats All living things are included in and rely on these places
Most past climate changes occurred slowly allowing plants and animals to adapt to the new environment or move someplace else
Plants and animals may not be able to react quickly enough to survive if future climate changes occur as rapidly as scientists predict
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Sea Level Risebull Global Warming may make the sea level become higher Whybull Warmer weather makes glaciers meltbull Melting glaciers add more water to the oceanbull Warmer weather also makes water expandbull When water expands in the ocean it takes up more space and the level of the sea rises
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Rising Sea Levels
bull When earthrsquos temperature rises sea level is likely to rise too
Higher temperature sea water to expand in volume
Ice caps at poles to melt
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Sea Level Risebull Sea level may rise between several inches and as much as 3 feet during the next centurybull Coastal flooding could cause saltwater to flow into areas where salt is harmful threatening plants and animals in those areasbull Oceanfront property would be affected by floodingbull Coastal flooding may also reduce the quality of drinking water in coastal areas
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Crops and Food Supply
bull Global warming may make the Earth warmer in cold places
bull People living in these areas may have the chance to grow crops in new areas
bull But global warming might bring droughts to other places where we grow crops
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What Might Happenbull This warming trend is expected to bring
droughts and flooding of low lying coastal areas as the polar ice caps melt and raise sea level
bull The expected negative impact of the greenhouse effect on human life has been assessed by some scientists to be second only to global nuclear war
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Climatic Change
bull Global warming will lead to an increase in the evaporation of water more water vapour
bull With more water vapour more rain fall is expectedbull But it is not evenly distributed
Dry areas severe drought condition water shortage and heat waves occurs
Wet areas floods and avalanches (landslides)
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Climatic Change
bull Other problems may arise Destroy food crop rice wheat and corn Affect animals need to migrate Encourage growth of weed and pests may
lead to diseases like dengue fever cholera which are deadly
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What can we do about itbull There are many little things that we can do to
make a difference to reduce the amount of greenhouse gases that we put into the atmosphere
bull Many greenhouse gases come from things we do every day
bull Driving a car or using electricity is not wrong We just have to be smartEg Try carpooling
>
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ways you can help make our planet better
bull Read ndash Learning about the environment is very important
bull Save Electricity ndash Whenever we use electricity we help put greenhouse gases into the air
Turn off lights the television and the computer
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ways you can help make our planet betterbull Bike Bus and Walk-
You can saves energy by sometimes taking the bus riding a bike or walking
bull Talk to Your Family and Friends ndash about global warming Let them know what yoursquove learned
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ways you can help make our planet better
bull Recycle ndash When you recycle you send less trash to the landfill and you help save natural resources like trees and elements such as aluminum
Recycle cans bottles plastic bags and newspapers
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ways you can help make our planet betterbull When You Buy Buy
Cool StuffBuy Products that
donrsquot use as much energy
Buy recyclable products instead of non-recyclable ones
bull Solar Energy ndash can be used to heat homes buildings water and to make electricity
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ways you can help make our planet betterbull Cars ndash cause pollution and release a lot of greenhouse gases into the air
Some cars are better for the environment ndash They travel longer on a smaller amount of fuel They donrsquot pollute as muchUsing these cars can help reduce can help reduce the amount of greenhouse gases in the air
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The Long-Term Stability of Earthrsquos Climateminus400000 years
bull The atmospheric concentration of CO2 measured from Antarctic ice core data implies that Earthrsquos climate has being pretty stable over the past 400000 years
bull It also shows a rapid increase of about 30 in the past few centurieshellip ndash 270 ppm (parts per
million) to 370 ppm
Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400000 years as inferred from Antarctic ice-core records The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006 From A V Fedorov et al Science 312 1485 (2006)17 18 Reproduced from EPA Climate Change Website
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Ultimatelybull The problem really is that we donrsquot know how the climate
machine works hence it is difficult at present to say that the warming is due to the increase of greenhouse gases and not the results of natural fluctuation of the global climate system
bull Recently there seems to be increasing evidence showing the connection between the global warming and industrial injection of greenhouse gases However the extent is still not clear
bull Hopefully with more research we can say more definitely in the near future
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What is acid rain
What is the effect of acid rain
What can be done about acid rain
What is alternative fuel
How to reduce our reliance on petroleum based fuel
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Acid Rain
Acid rain is basically rain that has a higher than normal acid level (low pH) (pH value between 5 and 56)
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Causes of Acid Rainbull Burning coal Oil and natural
gas in power stations makes electricity giving off sulphur dioxide gas
bull Burning petrol and oil in vehicle engines gives off nitrogen oxides as gases
bull These gases mix with water vapour and rainwater in the atmosphere producing weak solutions of sulphuric and nitric acids ndash which fall as acid rain
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
The ProblemPeople probably couldnt live without electricity Therefore coal will continue to be burnt Also electricity and energy are constantly being overused
Think of it this way every time you turn on a light switch or the television set without really needing to youre indirectly contributing to the acid rain problem
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
More problemsbull Acid rain can travel long distances
bull Often it doesnrsquot fall where the gas is produced High chimneys disperse (spread) the gases and winds blow them great distances before they dissolve and fall to Earth as rain
bull Eg gases produced in England and Western Europe can result in acid rain in Scotland and Scandinavia
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
How Acid Rain Affects The Environment
Acid rain is an extremely destructive form of pollution and the environment suffers from its effects Forests trees lakes animals and plants suffer from acid rain TreesThe needles and leaves of the trees turn brown and fall off Trees can also suffer from stunted growth and have damaged bark and leaves which makes them vulnerable to weather disease and insects
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
All of this happens partly because of direct contact between trees and acid rain but it also happens when trees absorb soil that has come into contact with acid rain The soil poisons the tree with toxic substances that the rain has deposited into it
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Lakes are also damaged by acid rain Fish die off and that removes the main source of food for birds Acid rain can even kill fish before they are born when the eggs are laid and come into contact with the acid
Fish usually die only when the acid level of a lake is high when the acid level is lower they can become sick suffer stunted growth or lose their ability to reproduce
Also birds can die from eating toxic fish and insects
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
BuildingsAcid rain dissolves the stonework and mortar of buildings (especially those made out of sandstone or limestone)It reacts with the minerals in the stone to form a powdery substance that can be washed away by rain
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
TransportCurrently both the railway industry and the aeroplane industry are having to spend a lot of money to repair the corrosive damage done by acid rain Also bridges have collapsed in the past due to acid rain corrosion
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
HumansHumans can become seriously ill and can even die from the effects of acid rain One of the major problems that acid rain can cause in a human being is respiratory problems
Many can find it difficult to breathe especially people who have asthma Asthma along with dry coughs headaches and throat irritations can be caused by the sulphur dioxides and nitrogen oxides from acid rain
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Acid rain can be absorbed by both plants (through soil andor direct contact) and animals (from things they eat andor direct contact) When humans eat these plants or animals the toxins inside of their meals can affect them Brain damage kidney problems and Alzheimers disease has been linked to people eating toxic animalsplants
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Research carried out in North America in 1982 revealed that sulphur pollution killed 51000 people and about 200000 people become ill as a result of the pollution
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
What are the
solutions to acid rain
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Solutionsbull 1 Sulphur dioxide can be removed from power
stations chimneys but this process is expensivebull 2 Reduce the amount of electricity we use - turn tvrsquos off at the mains donrsquot leave on standby- turn off lights when a room is not in usebull 3 Use renewable energy like wind power solar
panels tidal power and geothermal energybull 4 Fit catalytic converters to vehicle exhausts
which remove the nitrogen oxidesbull 5 Limit the number of vehicles on the roads and
increase public transport
Chemistry of oxides of Sulfur
SO2+ OH HOSO2
HOSO2 + O2 SO3 + HO2
SO3 + H2O H2SO4
CASE STUDY -2Taj Mahalrsquos marble cancer
H2SO4
Lime stone Gypsum
Stoichiometric air -fuel ratio
Determine air-to-fuel ratio required for complete combustion of gasoline
C7H13 +1025 O2 + 3854 N2 7CO2 + 65 H2O + 3854 N2
376 moles of N2 accompany every mole of O2 in air
Open book assignment
1 Write down the methods of controlling air pollution (maximum valid points)
Briefly describe about each methods (3-5 lines for each method)
2 Which alternative fuels can currently be used Write a brief description for each alternative fuels
3What are the major secondary pollutants and how are they formed
TECHNOLOGY FOR AIR POLLUTION CONTROL
TECHNIQUES WITHOUT USING EMISSIONS CONTROL DEVICES Process Change
Wind Geothermal Hydroelectric or Solar Unit instead of Fossil fired Unit
Change in Fuel eg Use of Low Sulfur Fuel instead of High Sulfur fuel
Good Operating Practices Good Housekeeping Maintenance
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
SOX CONTROL
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
Change to Low Sulfur Fuel middot Natural Gas
middot Liquefied Natural Gas
middot Low Sulfur Oil
middot Low Sulfur Coal
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
Change to Low Sulfur Fuel middot Natural Gas
middot Liquefied Natural Gas
middot Low Sulfur Oil
middot Low Sulfur Coal
Use Desulfurized Coal and Oil Increase Effective Stack Height middot Build Tall Stacks
middot Redistribution of Stack Gas Velocity Profile
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS (CONTD) Use Flue Gas Desulfurization Systems
Use Alternative Energy Sources such as Hydro-Power or Nuclear-Power
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
FLUE GAS DESULFURIZATION SO2 scrubbing or Flue Gas Desulfurization processes can
be classified asmiddot Throwaway or Regenerative depending upon whether the recovered
sulfur is discarded or recycled middot Wet or Dry depending upon whether the scrubber is a liquid or a solid
Flue Gas Desulfurization Processes The major flue gas desulfurization ( FGD ) processes are middot Limestone Scrubbingmiddot Lime Scrubbingmiddot Dual Alkali Processesmiddot Lime Spray Drying
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
LIMESTONE SCRUBBING
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
LIMESTONE SCRUBBING Limestone slurry is sprayed on the incoming flue gas
The sulfur dioxide gets absorbed The limestone and the
sulfur dioxide react as follows
CaCO3 + H2O + 2SO2 ----gt Ca+2 + 2HSO3-+ CO2
CaCO3 + 2HSO3-+ Ca+2 ----gt 2CaSO3 + CO2 + H2O
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
LIME SCRUBBING
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
LIME SCRUBBING The equipment and the processes are similar to those in
limestone scrubbing Lime Scrubbing offers better utilization of the reagent The operation is more flexible The major disadvantage is the high cost of lime compared to limestone
The reactions occurring during lime scrubbing are
CaO + H2O -----gt Ca(OH)2
SO2 + H2O lt----gt H2SO3
H2SO3 + Ca(OH)2 -----gt CaSO32 H2O
CaSO32 H2O + (12)O2 -----gt CaSO42 H2O
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
NOX CONTROL
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
BACKGROUND ON NITROGEN OXIDES There are seven known oxides of nitrogen
middot NO
middot NO2
middot NO3
middot N2O
middot N2O3
middot N2O4
middot N2O5
NO and NO2 are the most common of the seven oxides listed
above NOx released from stationary sources is of two types
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
GENERAL METHODS FOR CONTROL OF NOX EMISSIONS NOx control can be achieved by
middot Fuel Denitrogenation
middot Combustion Modification
middot Modification of operating conditions
middot Tail-end control equipment
middot Selective Catalytic Reduction
middot Selective Non - Catalytic Reduction
middot Electron Beam Radiation
middot Staged Combustion
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
FUEL DENITROGENATION
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite This produces ammonia and cleaner fuel
This technology can reduce the nitrogen contained in both naturally occurring
and synthetic fuels
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
COMBUSTION MODIFICATION Combustion control uses one of the following strategies
middot Reduce peak temperatures of the flame zone The methods are middot increase the rate of flame cooling middot decrease the adiabatic flame temperature by dilution
middot Reduce residence time in the flame zone For this we change the shape of the flame zone
middot Reduce Oxygen concentration in the flame one This can be accomplished by
middot decreasing the excess air middot controlled mixing of fuel and air middot using a fuel rich primary flame zone
CATALYTIC COMBUSTION
CATALYTIC EMISSION CONTROL
CARBON MONOXIDE CONTROL
FORMATION OF CARBON MONOXIDE middot Due to insufficient oxygen
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
GENERAL METHODS FOR CONTROL OF CO2 EMISSIONS Reducing energy consumption increasing the efficiency
of energy conversion
Switching to less carbon intensive fuels
Increasing the use of renewable sources
Sequestering CO2 through biological chemical or physical processes
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
CONTROL OF MERCURY EMISSIONS
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
MERCURY EMISSIONS Mercury exists in trace amounts in
Fossil fuels such as Coal Oil and Natural Gas Vegetation Waste products
Mercury is released to the atmosphere through combustion or natural processes
It creates both human and environmental risks Fish consumption is the primary pathway for human and
wildlife exposure United states is the first country in the world to regulate
mercury emissions from coal-fired power plants (March 15 2005)
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
Source Seingeur 2004 and Mason and Sheu 2002
Source Presentation by J Pacyna and J Munthe at mercury workshop in Brussels March 29-30 2004
Types of Sources
Worldwide Distribution of Emissions
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
CONTROL TECHNOLOGIES FOR MERCURY EMISSIONS Currently installed control devices for SO2 NOX and particulates in a
power plant remove some of the mercury before releasing from the stack
Activated Carbon Injection Particles of activated carbon are injected into the exit gas flow downstream of the boiler The mercury attaches to the carbon particles and is removed in a particle control device
Thief process for the removal of mercury from flue gasIt is a process which extracts partially burned coal from a pulverized coal-fired combustor using a suction pipe or thief and injects the resulting sorbent into the flue gas to capture the mercury
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
PARTICULATE MATTER CONTROL
Range 20 to 40000 mgm3First step Process controlSecond step Use of collection device
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
Slide 135
Slide 136
INDUSTRIAL SOURCES OF PARTICULATE EMISSIONS middot Iron amp Steel Mills the blast furnaces steel making furnaces middot Petroleum Refineries the catalyst regenerators air-blown asphalt
stills and sludge burners middot Portland cement industry middot Asphalt batching plants middot Production of sulfuric acid middot Production of phosphoric acid middot Soap and Synthetic detergent manufacturing middot Glass amp glass fiber industry middot Instant coffee plants
EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
The Long-Term Stability of Earthrsquos Climateminus400000 years
Ultimately
Slide 81
Acid Rain
Causes of Acid Rain
The Problem
More problems
How Acid Rain Affects The Environment
Slide 87
Slide 88
Buildings
Transport
Humans
Slide 92
Slide 93
Slide 94
Solutions
Slide 96
Slide 97
Slide 98
Slide 99
Slide 100
Technology for Air Pollution Control
Techniques Without Using Emissions Control Devices
Commonly Used Methods For Air Pollution Control
Slide 104
GENERAL METHODS FOR CONTROL OF SO2 EMISSIONS
General Methods for Control of SO2 Emissions (contd)
Flue Gas Desulfurization
Limestone Scrubbing
Limestone Scrubbing (2)
Lime Scrubbing
Lime Scrubbing (2)
Slide 112
Background on Nitrogen Oxides
General Methods For Control Of Nox Emissions
Fuel Denitrogenation
Combustion Modification
Catalytic Combustion
Catalytic Emission Control
Slide 119
Formation Of Carbon Monoxide
General Methods For Control of CO Emissions
Slide 122
Sources of Carbon Dioxide
General Methods For Control of CO2 Emissions
Slide 125
Mercury Emissions
Slide 127
Control Technologies for Mercury Emissions
Slide 129
Industrial Sources of Particulate Emissions
EFFECTS OF PARTICULATE EMISSIONS
General Methods For Control Of Particulate Emissions
General Methods For Control Of Particulate Emissions (Contd)
Particulate Collection Mechanism
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EFFECTS OF PARTICULATE EMISSIONS Primary Effects bull Reduction of visibility
bull size distribution and refractive index of the particles bull direct absorption of light by particles bull direct light scattering by particles bull 150 micro g m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
bull Soiling of nuisancebull increase cost of building maintenance cleaning of furnishings
and households bull threshold limit is 200 - 250 micro g m3 ( dust ) bull levels of 400 - 500 micro g m3 considered as nuisance
GENERAL METHODS FOR CONTROL OF PARTICULATE EMISSIONS Five Basic Types of Dust Collectors
Gravity and Momentum collectors middot Settling chambers louvers baffle chambers
