stationary source controls & source sampling

Stationary Source Controls & Source

Sampling

Marti Blad Ph.D., P.E.

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What we will learn Control of air pollution is possible

Physical, chemical or biological Control of air pollution is not perfect

“Shell game” Control mechanisms for particles are different

from those that control gasses Examples of types of controls

How air pollution control devices work Sampling of point sources

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Stationary Source Control

Philosophy of pollution prevention Modify the process: use different raw

materials Modify the process: increase efficiency Recover and reuse: less waste = less

pollution Philosophy of end-of-pipe treatment

Collection of waste streams Add-on equipment at emission points

AP control of stationary sources Particulates Gases

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Particulate Control Technologies

Remember this order: Settling chambers Cyclones ESPs (electrostatic

precipitators) Spray towers Venturi scrubbers Baghouses (fabric filtration)

All physical processes

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Settling Chambers “Knock-out pots” = initial separators Gravity and inertia forces

Simplest, cheapest, no moving parts Least efficient & large particles only

Creates solid-waste stream Can be reused

Pictures on next slides Baffle, Gravity, Centrifugal

Variety of styles

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Simple boxes= collection

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Cyclones Inexpensive, no moving parts More efficient than settling chamber

still better for larger particles Single cyclone or multi-clone design

In series or in parallel Creates solid-waste stream Picture next slide

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Notice shapes and fans

12Dry collection systems

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Venturi Scrubber

Detail illustrates cloud atomization from high-velocity gas stream shearing liquid at throat

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Venturi Scrubber High intensity contact between water

and gas => high pressure drop Venturi action modified spray tower High removal efficiency for small

particles Creates water pollution stream Can also absorb some gaseous

pollutants (SO2)

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Venturi and scrubbers

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Spray Towers Water or other liquid “washes out” PM Less expensive than ESP but more than

cyclone, still low pressure drop Variety of configurations Higher efficiency than cyclones Creates water pollution stream Can also absorb some gaseous

pollutants (SO2)

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Spray Tower

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ESPs Electrostatic precipitator More expensive to install, Electricity is major operating cost Higher particulate efficiency than

cyclones Can be dry or wet Plates cleaned by rapping Creates solid-waste stream Picture on next slide

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Electrostatic Precipitator Concept

Same Size & Shape

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Electrostatic Precipitator

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Electrostatic Precipitator

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Baghouses Fabric filtration – vacuum cleaner High removal efficiency for small particles Not good for wet or high temperature

streams Uses fabric bags to filter out PM Inexpensive to operate Bags cleaned by periodic shaking or air

pulse Creates solid-waste stream

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Pulse-Air-Jet Type Baghouse

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Baghouse in a Facility

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Baghouse= fabric filters

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Stationary Source Controls:

Gaseous Pollutants and Air Toxics

Source of Gaseous Pollutants

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Controlling Gaseous Pollutants: SO2 & NOx

Modify Process Switch to low-sulfur coals Desulfurize coal Washing-bioclean Gasification

Increase efficiency Low-NOx burners

Recover & Reuse Heat Staged combustion

Multi chambers Better process control

Flue-gas recirculation Gas is heat sink Absorbs heat from high flame area Lowers peak flame temperatures

Picture next slide 36

How FGR fits in process

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Controlling Gaseous Pollutants: CO & VOCs

Wet/dry scrubbers Used for PM but double w wet

Absorber solutions NOx and SOx included

Combustion Process Proper operating conditions Low NOx burners

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Scrubbers / Absorbers SO2 removal: “FGD” (flue gas

desulfurization) Lime/soda ash/citrate absorbing solutions Can create useable by-product OR solid

waste stream NOx removal—catalytic and non-

catalytic Catalyst = facilitates chemical reaction Ammonia-absorbing solutions Process controls favored over this

technology CO & CO2 removal Some VOC removal

VOC / CO Process Control Keep combustion HOT

Reuse & recycle heat Control cold start-ups, shut-downs, wet

inputs wood-fired, chemical incinerators, boilers

Increase residence time of gas in combustor

Unfortunately, things that reduce NOx tend to increase VOC’s Atmosphere in air combustion 78% N2

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How it might look together

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Flares

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Thermal Oxidation Chemical change = burn

CO2 and H2O ideal end products of all processes

Flares (for emergency purposes) Incinerators

Direct Catalytic = improve reaction efficiency Recuperative: heat transfer between inlet

/exit gas Regenerative: switching ceramic beds that

hold heat, release in air stream later to re-use heat

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Thermal Oxidation

Actual Oxidizers

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Regenerative

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Recuperative

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Carbon Adsorption Good for organics (VOCs) Both VOCs and carbon can be recovered

when carbon is regenerated (steam stripping)

Physical capture Adsorption & Absorption

Bettermarriageblanket.com Under-tec.com (farty pants)

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Adsorb

Absorb

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Stack Sampling

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Are you afraid of heights?

Stack sampling site setup

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What is source sampling?

Sample air pollutants at the source Stacks, vents, pt. of compliance, etc.

Sample specific pollutants Standard methods/protocols

Determine amount of a pollutant emitted Pollutant concentration

Mass pollutant per unit volume exhaust gas

Pollutant mass rate Mass pollutant emitted over a time

interval

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Why is source sampling done?

Evaluate process efficiency Evaluate equipment & control

performance Calculate process material balances Evaluate process economics Input of models (point source) Regulatory compliance

verification/permit review

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Before Sampling Sources Plan what will be done

Describe sampling objective, pollutants & site Identify responsible persons Sampling locations & access Standard methods

CFR, ASTM, AAC Sample type (grab, integrated or instrument) Methods – field sampling & lab analyses QA/QC requirements (field and lab) Health & safety considerations (plan) Each test is done 3 times

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Standard Methods – Basic

Method 1 Sample port location & number of ports,

determine absence of cyclonic flow Method 2

Stack gas velocity & flow rate Method 3

Gas MW & composition (%O2, %N2, %CO2) Method 4

Moisture content of stack gas Method 5

total particulate emissions Method 9

visual determination of opacity

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Standard Methods – Gases

Method 6 Sulfur dioxide

Method 7 Nitrogen oxides

Method 10 Carbon dioxide

Other methods Hydrocarbons Hydrochloric acid Hydrogen sulfide Fluoride Dioxins & furans PCBs, PAHs, Formaldehyde

(HCHO), others

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Continuous Emission Monitoring

Real-time detection of emissions gases Carbon dioxide Nitrogen oxides Sulfur oxides Hydrogen chloride Total hydrocarbons

Real time measure of flow and temperature

Continuous monitoring of opacity

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Continuous Emission Monitoring cabinet

CO NO NOx SO2 THCs Flow Temperature

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Is this something you should do?

Source sampling is Involved Expensive Time consuming

Source sampling requires Specialized training, experience &

equipment Laboratory support capacity Significant QA/QC

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What should you be able to do?

Know if it is being planned right

Know if it is being done right Know if it is reported right What resources are available

ITEP EPA CARB Smoke school

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What We just Covered Air pollutants can be controlled

involve tradeoffs, shell game Different controls for different types of

pollutants Source sampling is regulatory requirement

to ensure facilities are operating within permit requirements

Source sampling usually a series of methods

Source sampling not likely something you will do

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http://www.iowadnr.gov/Environment/AirQuality/HowAirPollutionIsControlled.aspx

Animated Control Technologies