a&ma&m university texas. a&ma&m university texas module 2 environmental challenges:...

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Module 2

ENVIRONMENTAL CHALLENGES:OVERVIEW FACING INDUSTRY

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During the past years, the perceptions of pollutions have changed, industry has to find ways to make products without creating pollution or to recover and reuse the materials that we have considered wastes, this philosophy is called pollution prevention.

Process Integration is highly compatible with this philosophy and complementary to it. This discipline encompasses a number of methodologies for designing and changing industrial processes, based on the unity of the whole process.

This module presents an overview of the major environmental problems facing various industries in North America.It also presents Process Integration as a systematic approach to solving environmental problems.

Purpose of Module 2

Two major industries (pulp and paper and petroleum refineries) are used as proof of the concept.

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STRUCTURE OF MODULE 2

TIER 1: Basic Concepts

TIER 2: Case Study

TIER 3: Computer-Aided Module

The module is divided into three tiers as follows:

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TIER 1 : BASIC CONCEPTS

This tier will provide a background including a general description of the major industries in North America, and focus on current environmental challenges facing the pulp and paper as well as the petroleum refining industries.

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TIER 1 : BASIC CONCEPTS

1. Major Industries in North America.

2.1 Driving forces, hurdles and potential.

2.3 Regulatory issues in North America.

2.2 Environmental discharges.

2.4 Best available environmental technologies for specific processes

2. Petroleum Industry

3. Pulp and Paper Industry





CONTENTS

This section in broken into three sections:

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1. MAYOR INDUSTRIES IN NORTH AMERICA

The most important industrial sectors in North America were sought not through their production but reviewing the quantity of their releases and pollutants.

Some statistics are organized by country :

CANADA USA MEXICO

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Canada is the world’s largest exporter of commodity-grade pulp and paper products, making this industry one

of the most important pollutant sector.

More Statistics: Canadian NPRITop 20 pollutantsMore information:

C A N A D A

INDUSTRIAL SECTORS RELEASING THE LARGEST QUANTITIES OF POLLUTANTS OFF-SIDE

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

Water, Sewageand OtherSystems

Pulp, Paper andPaperboard Mills

ElectricityGeneration,

Transmissionand Distribution

Pesticide,Fertilizer and

OtherAgricultural

chemicalManufacturing

Oil and GasExtraction

To

nn

es

Pulp, Paper and Paperboard mills

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PollutantTotal Releases

(tonnes)Ammonia 40915.0Nitrate ion in solution at pH<6.0 22500.8Methanol 20427.5Hydrochloric ac id 16595.3Sulphuric ac id 9387.3Hydrogen sulphide 7234.3Xylene (mixed isomers) 6327.4T oluene 5908.5Methyl ethyl ketone 4137.6Carbon disulphide 4065.3n-Hexane 3562.8Zinc (and its compounds) 3310.0Hydrogen fluoride 3257.7Ethylene 2472.0Ethylene glycol 2347.4Manganese (and its compounds) 2195.4Styrene 1833.0Dic loromethane 1777.2Isopropyl alcohol 1751.0Formaldehyde 1727.0Cyclohexane 1382.32-Butoxyethanol 1223.1Acetaldehyde 1095.4Benzene 1047.1n-Butyl alcohol 1047.1

Top 5 Pollutants Released On Site in the Largest Quantities, 2001

0.0

5000.0

10000.0

15000.0

20000.0

25000.0

30000.0

35000.0

40000.0

45000.0

Ammonia Nitrate ion insolution at

pH<6.0

Methanol Hydrochloricacid

Sulphuric acid

To

nn

es

Top 20 Pollutants Released On Site in the Largest Quantities, 2001

C A N A D A

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U S A

More Statistics: TRITop 20 pollutantsMore information:

Refineries and petroleum subproducts

are included.

T he U.S. petroleum industry is a strong contributor to the economic health of the United States, its production represents about the 25% of global production.

T he Pulp and Paper industry is also important since the U.S. is the world’s largest consumer or these products, both in total tones per year and in terms of consumption

per capita.

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Chemical

Total Production Related W aste Managed

(Pounds)

Methanol 2,331,011,667 T oluene 1,787,944,977 Hydrochloric ac id 1,504,105,058 Zinc compounds 1,355,504,817 Copper compunds 1,263,772,355 Ethylene 1,256,806,620 Copper 1,088,001,030 n-Hexane 970,193,833 Lead Compounds 965,794,108 Cumene 832,570,075 Ammonia 800,432,076 Propylene 797,566,959 Nitrate compounds 701,130,070 Sulfuric ac id 583,305,201 Ethylene glycol 565,972,276 1,2-Dichloroethane 561,860,469 Chlorine 552,091,471 Xylene 479,477,559 Manganese compounds 477,625,043 Nitric ac id 411,681,261

Subtotal (top 20) 19,286,846,925

Total (all chemicals) 26,735,591,638

Top 10 Chemicals with the Largest Total Releases, 2001

-

500,000,000

1,000,000,000

1,500,000,000

2,000,000,000

2,500,000,000

To

tal P

rod

uct

ion

Rel

ated

Was

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anag

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(P

ou

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U S A

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M E X I C O

More information

I n Mexico, the petroleum industry development is strongly linked to the employment rate, inflation, economic growth and capital

investment.

Hazardous Pollutants produced by Industry

Petroleum industries provide raw material for the chemical industry.e.g.

Gas natural Ammonia Fertilizers

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Pulp and Paper Petroleum

As we showed in the statistics section, there are two industries which are very important for the economy and development and also are causing serious environmental problems, making a link between the three countries.

This research is attempting to show the way in which Process Integration can be used successfully. For this challenge we use the two major industries in North America:

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No energy industry today is more engaged than petroleum in serving the global transportation, power generation, agricultural and consumer products sectors.

Oil and natural gas are essential drivers of economic growth, that implies enormous social and environmental responsibilities..

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2. Petroleum Industry

2.2 The Petroleum Refining Industry

2.2.1 Definition2.2.2 Primary Products2.2.3 Industrial Processes in the Petroleum Refining Industry2.2.4 Refinery flow diagram

2.3.1 Refinery air emission sources2.3.2 Types of wastewater produced in refineries2.3.3 Refinery Residuals2.3.4 Environmental discharges by process

2.4.1 U.S. Regulations2.4.2 Mexican Regulations2.4.3 General Regulations

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According to Abdallah S. Jum’ah, president of Saudi Aramco, energy today, must have three characteristics which are totally interdependent:

RELIABILITY OF SUPPLY

Any nation’s ability to sustain domestic development will depend on a ready resource of fuels and feedstock. No other energy supplier today is more capable of assuring such a continuity of supply than the petroleum industry.

REASONABLE PRICE

The petroleum industry is one of the most capital-intensive, high-maintenance, heavily regulated and excessively taxed industries operating worldwide.

ENVIRONMENTAL PROTECTION

Environment should be protected in order to achieve a sustainable development.

In order to secure reliable supplies of oil and natural gas, there must be a price mechanism sufficiently fair and stable to maintain inflows of investment capital. In turn, the investment will help fund the industry’s considerable measures to protect environment.

These three characteristics can act as:•DRIVING FORCES

•HURDLES

•POTENTIALSFirst beak volume 20. 10 October 2002

The characteristics of the Petroleum Industry are related. In order to understand them, the following diagram in shown.

2.1 DRIVING FORCES, HURDLES AND POTENTIALS

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•The petroleum refining industry is a strong contributor to the economic health of the United States and Mexico.

•For Mexico, this industry has become the most important part in the national economy, it is the first source of currency for the country.

•Hydrocarbons will long remain the resource of choice to fuel future economic progress worldwide. This is a reason not only to protect air, water and land resources, but also to keep serving society through these products.

DRIVING FORCES

Economic and environmental situations are involved in the development of the petroleum industry, but its final challenge must be to fulfill the society needs.

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HURDLES

The petroleum industry has been dramatically impacted over the last three decades by geopolitical disruptions and volatile world oil prices. Today refiners must deal with:

Increasing capital and operating costs of environmental compliance.

Volatile crude prices

Crude quality variability

Low marketing and transport profit margins

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The environmental impact produced by the petroleum industry covers the effects of all and each step in the energetic cycle, which means:

•explotation•extraction •refining •transportation •storage •consumption •releases

HURDLES

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POTENTIALSThe natural source itself and the reliability of supply must be the greatest potential for the country that posses them.

Technology plays an important role in developing the petroleum industry. Also, research and development have a great deal to do with keeping petroleum prices reasonable. In the past, new technologies had improved our methods of exploration and production, along with downstream efficiencies that yield cleaner-burning automotive fuels and higher-value products from every barrel of crude oil, allowing the increase and the improvement of the industry.

The U.S. is the largest, most sophisticated producer of refined petroleum products in the world, representing about 25% of global production.

Social and environmental issues will be decisive for the framework conditions for the future oil and gas industry. Technology is a tool that could help in achieving this task.

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2.2 PETROLEUM REFINING INDUSTRY

Petroleum refining is the physical, thermal and chemical separation of crude oil into its major distillation fractions which are then further processed through a series of separation and conversion steps into finished petroleum products.

Petroleum refineries are a complex system of multiple operations and the operations used at a given refinery depend upon the properties of the crude oil to be refined and the desired products.

2.2.1 DEFINITION

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2.2.2 The primary products of this industry are divided into three categories:

FUELSCHEMICAL INDUSTRY

FEEDSTOCKS

naphtha, ethane, propane, butane, ethylene, propylene, butylenes, butadiene, benzene, toluene and xylene

FINISHED NON FUEL PRODUCTS

solvents, lubricating oils, greases, petroleum wax, petroleum jelly, asphalt and coke

motor gasoline, diesel and distillate fuel oil, jet fuel, residual fuel oil, kerosene and coke

These products are used as primary input to a vast number of products: fertilizers, pesticides, paints, waxes, thinners, solvents cleaning fluids, detergents, refrigerants, anti-freeze, resins, sealants, insulations, latex, rubber compounds, hard plastics, plastic sheeting and synthetic fibers.

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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY

The process of oil refining involves five major processes which are briefly described:

SEPARATION PROCESSES

These processes involve separating the different fractions of hydrocarbon compounds that make up crude oil base on their boiling point differences. Additional processing of these fractions is usually needed to produce final products to be sold within the market.

• Atmospheric distillation• Vacuum distillation• Light ends recovery (gas processing)

SEPARATION CONVERSION TREATING BLENDING AUXILIARY

ASSOCIATED OPERATIONS

In order to understand where the environmental discharges come from, we will make a review of the refining process.

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ASSOCIATED OPERATIONS

Include processes used to bread down large longer chain molecules into smaller ones by heating using catalysts.

• Cracking (thermal and catalytic)• Reforming• Alkylation• Polymerization• Isomerization• Coking• Visbreaking

CONVERSION PROCESSES


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ASSOCIATED OPERATIONSTREATING PROCESSES

Petroleum-treating processes are used to separate the undesirable components and impurities such as sulfur, nitrogen and heavy metals from the products.

• Hydrodesulfurization• Hydrotreating• Chemical sweetening• Acid gas removal• Deasphalting


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ASSOCIATED OPERATIONSBLENDING/COMBINATION PROCESSES

These are used to create mixtures with the various problem fractions to produce a desired final product, some examples of this are lubricating oils, asphalt, or gasoline with different octane ratings.

• Storage• Blending• Loading• Unloading


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ASSOCIATED OPERATIONSAUXILIARY PROCESSES

Processes that are vital to operations by providing power, waste treatment and other utility services. Products from these facilities are usually recycled and used in other processes within the refinery and are also important in regards to minimizing water and air pollution.

• Boilers• Waste water treatment• Hydrogen production• Sulfur recovery plant


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Stabilizer

At m

osp

her i

cD

isti

llat i

on

VacuumDistillation

SweeteningUnit

Visbreaker

Hydrotreating

CatalyticCracking

Solvent Extraction and

Dewaxing

LPH and Gas

Gasoline

Naphta

Middle Distillates

Gas Oil

Lube-BaseStocks

Sweet Gasoline

Middle Distillates

Gas

Gasoline

Light Gas Oil

Lube Oil

Waxes

Gasoline, Naphtha and Middle distillates

Fuel Oil

Asphalt

Tre

ati

ng a

nd B

lend

ing

Refinery fuel gas

Refinery fuel oil

Industrial fuels

Asphalts

Greases

Lube oils

Aviation fuels

Diesels

Heating oils

LPG

Gasoline

Solvents

Washed Crude

2.2.4 REFINERY FLOW DIAGRAM

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2.3 ENVIRONMENTAL DISCHARGES

Now, that we have seen an overview of the Refinery Process, we can make some questions:

What is this industry discharging?How is it discharged? Where does it come from?

In order to answer these questions, this section will show:

Air emission sourcesWastewater sourcesResidualsEnvironmental discharges by process

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2.3.1 REFINERY AIR EMISSIONS SOURCES

COMBUSTION EMISSIONS: associated with the burning of fuels in the refinery, including fuels used in the generation of electricity.

EQUIPMENT LEAK EMISSIONS (fugitive emissions): released through leaking valves, pumps, or other process devices. They are primarily composed of volatile compounds such as ammonia, benzene, toluene, propylene, xylene, and others.

PROCESS VENT EMISSIONS: typically include emissions generated during the refining process itself. Gas streams from all refinery processes contain varying amounts of refinery fuel gas , hydrogen sulfide and ammonia.

STORAGE TAND EMISSIONS released when product is transferred to and from storage tanks.

WASTEWATER SYSTEM EMISSIONS from tanks, ponds and sewer system drains.

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2.3.2 TYPES OF WASTEWATER PRODUCED IN REFINERIES

SURFACE WATER RUNOFF is generated intermittently and may contain constituents from spills to the surface, leaks in equipment and materials in drains.

COOLING WATER which normally does not come into contact with oil streams and contains less contaminants than process wastewater. It may contain chemical additives used to prevent scaling and biological growth in heat exchanger pipes.

PROCESS WASTEWATER that has been contaminated by direct contact with oil accounts for a significant portion of total refinery wastewater. Many of these are sour water streams and are also subjected to treatment to remove hydrogen sulfide and ammonia.

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2.3.3 REFINERY RESIDUALS

Most refinery residuals are in the form of sludge, spend caustics, spend process catalysts, filter clay, and incinerator ash.

NON-HAZARDOUS RESIDUALS are incinerated, landfilled or regenerated to provide products that can be sold off-site or returned for re-use at a refinery.

HAZARDOUS WASTES are regulated under the Resource Conservation and Recovery Act (RCRA). Listed hazardous wastes include oily sludge, slop oil emulsion solids, dissolved air flotation floats, leads tank bottom corrosion solids and waster from the cleaning of heat exchanger bundles.TOXIC CHEMICALS are also use in large quantities by refineries. These are monitored through the Toxic Release Inventory (TRI).

These residuals could be classified as follows:

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PollutantAverage ratekg/t of crude

Particulate matter 0.8Sulfur oxides 1.3Nitrogen oxides 0.3Benzene, tolueneand xylene (BTX) 0.0025VOC 1

PollutantAverage ratemg/l ofwastewater

BOD 150-250COD 300-600Phenols 20-200Oil 100-300Benzene 1-100Benzopyrene 1-100Heavy metals 0.1-100Chrome 0.2-10

2.3.4 DISCHARGES

AIR EMISSIONSLIQUID EFFLUENTS

Approximately 3.5-5 cubic meters of wastewater per ton of crude are generated when cooling water is recycled.

Refineries generate solid wastes and sludges ranging from 3 to 5 kg per ton of crude processed, 80% of this sludges may be considered hazardous because or the presence of toxic organics and heavy metals.

SOLID WASTES

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Process Air Emissions Process Waste Water Residual Wastes Generated

Crude oil desalting Heater stack gas (CO,

SOx, NOx, hydrocarbons

and particulates), fugitive emissions (hydrocarbons)

Flow = 2.1 Gal/Bbl Oil,

H2S, NH3, phenol, high

levels of suspended solids, dissolved solids, high BOD, high temperature

Crude oil/desalted sludge (iron rust, clay, sand, water, emulsified oil and wax, metals)

Atmospheric distillation

Heater stack gas (CO,


and particulates), fugitive emissions (hydrocarbons)

Vacuum distillation Steam ejector emissions (hydrocarbons), heater

stack gas (CO, SOx,

NOx, hydrocarbons and

particulates), vents and fugitive emissions (hydrocarbons).

Thermal Cracking/Visbreaking



and particulates), vents and fugitive emissions (hydrocarbons)

Flow = 2.0 Gal/Bbl Oil,

H2S, NH3, phenol,

suspended solids, high pH, BOD, COD.

Typically, little or no residual waste generated.

Coking Heater stack gas (CO,


and particulates), vents and fugitive emissions (hydrocarbons) and decoking emissions (hydrocarbons and particulates).

Flow = 1.0 Gal/Bbl High

pH, H2S, NH3,

suspended solids, COD.

Coke dust (carbon particles and hydrocarbons).

Flow = 26 Gal/Bbl Oil,

H2S, NH3 suspended

solids, chlorides, mercaptans, phenol, elevated pH.

Typically, little or no residual waste generated.

2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESSPART 1

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Catalytic Cracking Heater stack gas (CO,


and particulates), fugitive emissions (hydrocarbons) and catalyst regeneration

(CO, NOx, SOx, and

particulates).

Flow 1.5 Gal/Bbl High levels of oil, suspended solids, phenols

cyanides, H2S, NH3,

high pH, BOD, COD.

Spent catalysts (metals from crude oil and hydrocarbons), spent catalyst fines from electrostatic precipitators (aluminum silicate and metals).

Catalytic Hydrocracking



and particulates), fugitive emissions (hydrocarbons) and catalyst regeneration

(CO, NOx, SOx, and

catalyst dust).

Flow = 2.0 Gal/Bbl High COD, suspended solids,

H2S, relatively low levels

of BOD.

Spent catalysts fines (metals from crude oil, and hydrocarbons).

Hydrotreating/Hydroprocessing



and particulates), vents and fugitive emissions (hydrocarbons) and catalyst regeneration

(CO, NOx, SOx, and

catalyst dust).

Flow = 1.0 Gal/Bbl H2S.

NH3, High pH, phenols

suspended solids, BOD, COD.

Spent catalyst fines (aluminum silicate and metals).

Alkylation Heater stack gas (CO,



Low pH, suspended solids, dissolved solids,

COD, H2S, spent

sulfuric acid.

Neutralized alkylation sludge (sulfuric acid or calcium fluoride, hydrocarbons).

Isomerization Heater stack gas (CO,



Low pH, chloride salts, caustic wash, relatively

low H2S and NH3.

Calcium chloride sludge from neutralized HCl gas.


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Polymerization H2S from caustic

washing.

H2S, NH3, caustic wash,

mercaptans and ammonia, high pH.

Spent catalyst containing phosphoric acid.

Catalytic Reforming Heater stack gas (CO,


and particulates), HCl potentially in light ends), vents and fugitive emissions (hydrocarbons)

Flow = 6.0 Gal/Bbl High levels oil, suspended solids, COD. Relatively

low H2S.

Spent catalyst fines from electrostatic precipitators (alumina silicate and metals).

Solvent Extraction Fugitive solvents Oil solvents Little or no residual wastes generated.

Dewaxing Fugitive solvents, heaters Oil solvents Little or no residual wastes generated.

Propane Deasphalting



and particulates), fugitive propane.

Oil solvents Little or no residual wastes generated.

Merox treating Vents and fugitive emissions (hydrocarbons and disulfides).

Little or no wastewater generated

Spent Merox caustic solution, waste oil-disulfide mixture.

Wastewater treatment

Fugitive emissions (H2S,

NH3, and hydrocarbons)

Not Applicable API separator sludge (phenols, metals and oil), chemical precipitation sludge (chemical coagulants, oil), DAF floats, biological sludges (metals, oil, suspended solids), spent lime.


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Gas Treatment and Sulfur Recovery

SOx, NOx, and H2S from

vent and tail gas emissions.

H2S, NH3, amines,

Stretford solution.

Spent catalyst.

Blending Fugitive emissions (hydrocarbons)


Little of no residual waste generated.

Heat Exchanger cleaning

Periodic fugitive emissions (hydrocarbons)

Oily wastewater generated

Heat exchanger sludge (oil, metals, and suspended solids)

Storage Tanks Fugitive emissions (hydrocarbons)

Water drained from tanks contaminated with tank product

Tank bottom sludge (iron rust, clay, sand, water, emulsified oil and wax, metals)

Blowdown and flare Combustion products

(CO, SOx, NOx, and

hydrocarbons) from flares, fugitive emissions


Little or no residual waste generated.


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2.4 REGULATORY ISSUES IN NORTH AMERICA

The Petroleum Refining Industry is unique in that the environmental requirements aimed at the industry are of two basic types:

For the purpose of this module, we focus on refineries, which will be used to show some Process Integration techniques.

Petroleum refineries are complex plants, and the combination and sequence of processes is usually very specific to the characteristics of the raw material and the products. For this reason the regulations for this sector become very specific and dispersed because an unit have regulations for water, air and land discharges, all of these managed by different official documents.

Requirements directed at reducing the environmental impacts of the refineries themselves.

Requirements mandating specific product qualities for the purpose of reducing the environmental impacts associated with the downstream use of the product.

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In the case of the United States, there are numerous federal regulations affecting the Refinery Industry. The Environmental Protection Agency (EPA) contains several regulatory documents depending on the kind of resource that they pretend to protect, (e.g. Air, water and soil).

Each one of these documents presents requirements which apply for every industrial sector. Then, when the requirements for a certain industry are needed, specific parts of the document should be used. For example,

The Clean Air Act Amendments of 1990 has some programs for reducing air emissions from industry in which refineries are included:

New Source Review, New Source Performance StandardsNational Emission Standards for Hazardous Air Pollutants

At the same time, the New Source Performance Standards have some sections for Refineries:

Subpart J Standards of Performance for Petroleum RefineriesSubpart KKK Standards of Performance for Volatile Organic Liquid Storage Vessels.Subpart GG Standard of Performances for Stationary Gas Turbines.Subpart GGG Standards of Performance for Equipment Leaks of VOC in Petroleum Refineries

2.4.1 U.S. REGULATIONSEPA

website

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All these sections contain flow diagrams, where depending on the process that is being used, it must be applied certain norm.

http://www.tnrcc.state.tx.us/permitting/airperm/opd/60/60hmpg.htm

To find more information:

2.4.1 U.S. REGULATIONS

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Requirement Provisions That Affect Petroleum Refining

Clean air Act of 1970 (CAA) and regulations National Ambient Air Quality Standards (NAAQS) fix six constituents; new standards underNAAQS that require control of particulate matter of 2.5 microns or smaller; lead-free gasoline;low sulfur fuel; reformulated gasoline; hazardous air pollutants; visi

Clean Air Act Amendments of 1990 (CAAA) and regulations thereunder.

Oxygenated Fuels Program for “ nonattainment areas” low sulfur highway diesel fuel;Reformulated fuels Program; Leaded Gasoline Removal Program; Reid Vapor pressureregulations to reduce VOCs and other ozon precursors; New Source Review for new orexpande

Resource Conservation and Recovery Act (RCRA)

Standards and regulations for handling and disposing of solid and hazardous wastes.

Clean Water Act (CWA) Regulates discharges and spills to surface waters; wetlands.

Safe Drinking Water Act (SDWA) Regulates disposal of wastewater in underground injection wells

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)

“superfund”, liability for CERCLA hazardous substances could apply to wastes generatedduring refining, includes past releases, exempts petroleum and crude oil; provides for naturalresource damages.

Emergency Planning and Community Right-to-Know (EPCRA).

Requires annual reporting on the releases and transfers of listed toxic chemicals; reportingpresence of “extremely hazardous substances’ in excess or threshold planning quantities;reporting certain releases of CERCL hazardous substances and EPCRA extrem

1990 Oil Pollution act and Spill Prevention Control and Countermeasure Plans

Liability against facilities that discharge oil to navigable waters of pose a threat of doing so.

OSHA Health Standards and Process Safety Management Rules

Limits benzene and other chemical exposures in the workplace, safety plans required in allrefineries.

Toxic Substances Control Act Collection of data on chemicals for risk evaluation, mitigation and control; can ban chemicalsthat pose unreasonable risks.

Energy Policy Act of 1992 Use of alternative fuels for transportation; efficiency standards for new federal buildings,buildings with federally backed mortgages, and commercial and industrial equipment; R&Dprograms for technologies; will reduce demand for petroleum products.

FEDERAL REQUIREMENTS AFFECTING THE REFINERY INDUSTRY

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In Mexico, SEMARNAT (Secretaria de Medio Ambiente y Recursos Naturales) is in charge or the environmental regulations, but it does not cover all aspects of a refinery because some of them are very specific, for example,

Proyecto NOM-088-ECOL-1994 Establish the maximum permissible levels of pollutants in the water discharges that become from storage and distribution of petroleum and its derivates.

A classification of these norms is found in this website:

http://www.semarnat.gob.mx

Then, if the complete document is needed, you can check here:http://cronos.cta.com.mx/cgi-bin/normas.sh/cgis/index.p

2.4.2 MEXICAN REGULATIONS

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Parameter Maximum valuePM 50

Nitrogen oxidesa 460

Sulfur oxides 150 for sulfur recovey units; 500 for other

unitsNickel and vanadium (combined)

2

Hydrogen sulfide 152

Parameter Maximum valuepH 6--9BOD 30COD 150TSS 30Oil and grease 10Chromium Hexavalent 0.1 Total 0.5Lead 0.1Phenol 0.5Benzene 0.05Benzo(a)pyrene 0.05Sulfide 1

Nitrogen(total)a 10Temperature increase <=3 C

Besides all these complicated regulations, an specialized agency of the United Nations, the World Bank, has established emission levels for the design and operation of refineries, although country legislation should be accomplished. The guidelines given below present emissions levels normally acceptable to the World Bank Group.

Emissions from the Petroleum Industry(milligrams per normal cubic meter)

Effluents from the Petroleum Industry(milligrams per liter)

Generation of sludges should be minimized to 0.3 kg per ton of crude processed, with a maximum of 0.5 kg per ton of crude processed.

Solid Wastes

2.4.3 GENERAL REGULATIONS

World Band Group, 1998. Pollution Prevention and Abatement Handbook. World Bank Group. Pages 377-381.

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Primary wastewater treatment

Consists on the separation of oil, water and solids in two stages.

1st stageAPI separator or

Corrugated plate interceptor.

2nd stageChemical and physical methods are utilized to separate emulsified oils from the wastewater.

www.panamenv.com

Physical methods may include the use of series of settling ponds with a long retention time, or the use of dissolved air flotation (DAF).

Chemicals, such as ferric hydroxide or aluminum hydroxide are used to coagulate impurities.

More information about the equipment

More information about the equipment

www.panamenv.com

2.5 ENVIRONMENTAL TECHNOLOGIES USED IN THE PETROLEUM INDUSTRY

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Secondary wastewater treatment

Dissolved oil and other organic pollutants may be consumed biologically.

Biological treatment may require oxygen through different techniques:

• Activated sludge units• Trickling filters• Rotating biological contactors.

Generates bio-mass waste which is treated anaerobically.

Polishing

Some refineries employ it as an additional stage of wastewater treatment to meet discharge limits.

• Activated carbon• Anthracite coal• Sand

2.5 ENVIRONMENTAL TECHNOLOGIES PETROLEUM INDUSTRY

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In order to meet the SOx emissions limits and to recover saleable sulfur, refinery process off-gas streams should be treated.

Process off-gas streams contain high concentrations of:

hydrogen sulfide + light refinery fuel gases.

This is accomplished by: • Dissolving the hydrogen sulfide in a chemical solvent such as diethanolamine (DEA) in an absorption tower.• Using dry adsorbents such as molecular sieves, activated carbon, iron sponge and zinc oxide.

These fuel gases (methane and ethane) need to be separated before elemental sulfur can be

recovered.

Amine + hydrogen sulfide Is then heated and steam stripped to remove the hydrogen sulfide gas.

Two processes are typically combined to remove sulfur from the hydrogen sulfide gas streams:

Claus Process

Beaven Process

Scot Process

Wellman-Land Process

hydrogen sulfide


Gas treatment and Sulfur Recovery

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Other emissions sources come from periodic regeneration of catalysts, these emissions may

contain:

high levels of carbon monoxide + particulates + VOCs.

CARBON MONOXIDE BOILERTo burn carbon monoxide and VOCs

ELECTROSTATIC PRECIPITATOR OR CYCLONE SEPARATORTo remove particulate matter

Before being released to the atmosphere


Gas treatment

Solid waste treatment

Sludge treatment use bioremediation or solvent extraction, followed by combustion of the residues or by use for asphalt. The residue could require stabilization before disposal to reduce the leachability of toxic metals.

www.e2t.com/E2T/app_pc05.htm

More information:www.ppcesp.com

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Pulp and Paper Petroleum

As we showed in the statistics section, there are two industries which are very important for the economy and development and also are causing serious environmental problems, making a link between the three countries.

This research is attempting to show the way in which Process Integration can be used successfully. For this challenge we use the two major industries in North America:

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The uses and applications for paper and paper products are limitless. It is important because it gives us the opportunity or recording, storage and dissemination of information. Also, it is the most widely used wrapping and packaging material and it is also used for structural applications.

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3. Paper Industry

3.2 Overview of the Pulp and Paper process.

3.2.1 Different methods3.2.2 Main steps of the process

3.4.1 U.S. Regulations3.4.2 Canadian Regulations3.4.3 General Regulations

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3.1 DRIVING FORCES

The U.S. forest products industry makes a strong contribution to the national economy, producing 1.2% of the U.S. GDP.

The industry employed almost 1.3 million people just in the United States.

Paper and wood products are used in many different applications both at home and at work.

The Pulp and Paper Industry provides employment for vast number of people and plays a vital role in the overall economy of both the United States and Canada.

Pulp and paper is the third largest industrial polluter to air, water and land in both Canada and the United States, and releases well over a hundred million kg of toxic pollution each year.

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3.1 HURDLES

The Pulp and Paper industry in North America is threatened by:

Plantation forests of fast growing tree species are being developed such countries as Brazil, Indonesia, Chile.

Quality-stand of timber have become more difficult and costly to access.

New competitors, with lower fiber costs, have entered the market (e.g. Russia, Austria, Chile, Australia, New Zealand and Indonesia).

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3.1 POTENTIALS

The strong U.S. economy of the late 1990s has revived the pulp and paper industry. Now, this industry is one with the biggest average annual pace growth.

The Pulp and paper industry producers have some advantages:

•Potential of the US and Canadian market.

•Access to a substantial endowment of timber suitable for harvesting as saw and pulp logs.

•The high quality of wood-fiber derived from them.

•Access to low-cost, secure supplies of energy.

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The manufacture of pulp for paper and cardboard employs different methods:

CHEMIMECHANICAL A combination of the previous processes.

Separates fibers by such methods as disk abrasion and billeting, this pulp can be used without bleaching to make printing papers for applications in which low brightness is acceptable. For other applications, bleaches like peroxides and hydrosulfites must be used.

MECHANICALChemical pulps are made by cooking the raw materials, using the kraft (sulfate) and sulfite processes. Kraft processes produce a variety of pulps used mainly for packaging and high-strength papers and board. Oxygen, hydrogen peroxide, ozone, peracetic acid, sodium hypochlorite, chlorine dioxide, chlorine, and other chemicals are used to transform lignin into an alkali-soluble form.

CHEMICAL

3.2 OVERVIEW OF THE PULP AND PAPER PROCESS

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The main steps in pulp and paper manufacturing are:

These steps are common for the three processes, although the difference is the units they use for each task.

Wood yard

Pulping

Bleaching

Paper manufactur

e

The significant environmental impacts of the manufacture of pulp and paper result from the pulping and bleaching processes.


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PROCESS PURPOSE MAJOR TECHNOLOGIES

PULPING Convert wood chips of wastepaper into fibers suitable for papermaking.

Chemical (Kraft, sulfite)- digesters, mechanical – refiners, semi chemical – digesters & refiners.

CHEMICAL RECOVERY (KRAFT

PULPING)

Recovery of inorganic chemicals from spend pulping liquor and combustion of organic residuals to produce energy.

Evaporation concentration recovery boiler, causticizing, calcining.

BLEACHING Brighten of whiten pulps by using chemicals to selectively remove lignin.

Chlorine dioxide, oxygen, hypochlorite, peroxide, ozone, of chlorination- upflow of downflowtowers, vacuum washers, pumps, mixers.

PAPER MANUFACTURE

Prepare stock from pulp, sheet, dewater, dry, caleder.

Heat box, sheet forming table.


This table presents the purpose of each one of the processes presented before and the technologies used to reach their task.

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3.3 ENVIRONMENTAL DISCHARGES

Average rates

Kg/t of ADP

Black liquor oxidation

Reduced sulfur compounds:

Hydrogen sulfide

Methyl mercaptan

Dimethyl sulfide

Dimethyl disulfide

Particulate matter 75 -150

Sulfur oxides 0.5 - 30

Nitrogen oxides 1--3

Volatile organic compounds (VOCs) 15

Pulping

Sulfur oxides 15-30Steam and electricity generatin units

Fly ash 100

Pollutant

0.3-3

Average ratesKg/t of ADP

Wastewaters 20-250 m3/tBOD 10--40Total suspended solids 10--50COD 20-200Chlorinated organic compounds:DioxinsFuransAdsorbable organic halides

Pollutant

0-4

The principal solid wastes of concern include wastewater treatment sludge : 50-150 kg/t of ADP.

AIR EMISSIONS LIQUID EFFLUENTS

SOLID WASTES

ADP: Air dried pulp, defined as 90% bone-dry fiber and 10% water.t:metric ton.

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U.S. REGULATIONSThe key federal group responsible for the environment is the EPA, which is a regulatory agency that establish and enforce environmental standards.

The purpose of the EPA is to conduct research and suggest solutions to environmental problems. Simultaneously, it has an obligation to monitor and analyze the environment.

The components of the legislation that most influence the pulp and paper industry are the effluent limitation guidelines that define minimum effluent conditions for 1977 and 1983.

WATER REGULATIONS

AIR REGULATIONS

3.4 REGULATORY ISSUES

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Up to 1970, stream quality standards in the United States were largely the responsibility of individual states. The federal government became dominant until 1970, when the Environmental Protection Agency (EPA) was established.

In 1972, the Federal Water Pollution Control Act stipulated a step-wise schedule for meeting conventional discharge criteria, the first target level by 1977 being equivalent to “best practical technology” (BPT), and the second target level by 1983 being equivalent to “best available technology economically achievable”(BATEA).

In the early 1980’s these regulations included toxic or sub-toxic substances through the National Pollutant Discharge Elimination System (NPDES). Among these were a number of byproducts of the chlorine bleaching process. Later, the EPA has increased the list of priority pollutants.

The U.S federal regulations that deal with environmental protection change every four years. It is a constant challenge to this industry to keep up-to-date.

BACKGROUND

PARAMETERSPARAMETERSPARAMETERS

TOXIC POLLUTANTS

WATER REGULATIONS

Other agencies:

• Effluent Standards and Water Quality Information Advisory Committee (ES&WQIAC).• The Council of Environmental Quality.• National Commission on Water Quality

BACKGROUND

TOXIC POLLUTANTS

New source performance stardard in kg/kkgMaximum 30-day average Maximum /day

Subcategory BDO5 TSS BDO5 TSSDissolving kraft 6.1 8.35 11.75 15.5Market kfaft 2.65 2.9 5.15 5.35BCT kraft 3.7 5 7.05 9.3Fine Draft 2.55 3.75 4.95 7Papergrade sulfite 4.65 2.9 8.98 5.35Market sulfite 4.65 2.9 8.95 5.35Low alpha dissolving sulfite 11.15 10 21.45 18.6High alpha dissolving sulfite 13.8 9.45 26.5 17.6GW: chemimechanical 3.9 3.3 7.5 6.15GW: thermomechanical 2.3 3.15 4.45 5.85GW:CMN papers 2 3.15 3.85 5.85GW: fine papers 1.9 3 5.6 5.6Soda 3.15 4.3 60 7.95Deink 3.9 4 7.5 7.45NI fine papers 1.35 1.4 2.6 2.6NI tissue papers 2.15 2.2 4.15 4.1NI tissue papers (FWP) 1.9 1.95 3.7 3.65

GW: groundwood NI: nonintegrated

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Acenaphthene DDT and metabolitesAcrolein DichlorobenzeneAcrylonitrile DichlorobenzidineAldrin/dieldrin DichloroethylenesAntimony and compounds 2,4-DichlorophenolArsenic and compounds Dichloropropane and dichloropropeneAsbestos 2,4-Dimethylphenol

DinitrotolueneBenzene DiphenylhydrazineBenzidineBeryllium and compounds Endosulfan and metabolites

EndrinCadmium and compounds EthylbenzeneCarbon tetrachlorideChlordane HaloethersChlorinated benzenes HalomethanesChlorinated ethanes Heptachlor and metabolitesChloralkyl ethers HexachlorocyclohexaneChlorinated napthalene HexachlorocyclopentadieneChlorinated phenolsChloroform Isophorone2-ChlorophenolChromium and compounds Lead and compoundsCopper and compoundsCyanides Mercury and compoundsNaphtalene Silver and compoundsNickel and compoundsNitrobenzene 2,3,7,8-Tetrachlorodibenzo-p-dioxinNitrophenols TetrachloroethyleneNitrosamines Thalium and compounds

ToluenePentachlorophenol Toxaphene Phenol TrichloroethylenePhthalate estersPolychlorinated bephenyls Vinyl chloridePolynuclear aromatichydrocarbons Zinc and compounds

Selenium and compounds

TOXIC POLLUTANTS

Settlement agreement toxic pollutants:

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BACKGROUNDBACKGROUNDBACKGROUND

PARAMETERS

GENERAL INFORMATION

AIR REGULATIONS

Talking about the Pulp and Paper industry, the objective of air regulations is the elimination of hazardous air pollutants such as methanol, total reduced sulfur gases, and chlorine. Maximum achievable control technology (MACT) is the level of control at the average of the best 12% of the mills in the EPA data base of that category.

The MACT rules have three tiers sorted by mill type. •MACT I is for chemical pulp mills including kraft, semichemical, and sulfite.•MACT II is for kraft, soda, semichemical and sulfite combustion sources including recovery units, smelt dissolving tanks, and lime kilns. •MACT III is for paper machines, mechanical pulping and secondary fiber and nonwood fiber.

The Clean Air Act of 1963, was a benchmark piece of legislation. It represented the first allocation by the federal government of significant funds for air pollution problems.

In 1970, President Richard Nixon decided to form the U.S. Environmental Protection Agency, which absorbed the National Air Pollution Control Administration. The Clean Air Act Amendments of 1970, covered three primary areas:•Attainment and maintenance of National Ambient Air Quality Standards (NAAQS).•Establishment of regulations covering the emission of certain pollutants from mobile and stationary sources.•Establishment of New Source Performance Standards (NSPS).EPA established standards for seven pollutants: sulfur dioxide, total suspended particulates, carbon monoxide, nitrogen oxides, photochemical oxidants, hydrocarbons, and lead. NAAQS needed review every five years. The 1990 CAA is probably the most dramatically impacting air pollution legislation of all time became law in 1990. Possibly most important to the pulp and paper industry was the new air toxics control program. The 1990 law relied on technology to control emissions of 189 hazardous air pollutants.

Mill type Emission point PM HAP TGO HAP

Kraft and soda

Recovery funace PM < 0.015 grains/drystandard cubic foot at 8%oxygen

< 0.025 lb/ton of blackliquor solids (BLS)

Smelt dissolving tank PM < 0.12 lb/ton BLS None

Lime kiln PM < 0.01 grains/drystandard cubic foot at 8%oxygen

None

Sulfite

Sulfite combustionunits

PM < 0.02 grains/drystandard cubic foot at 8%oxygen

Stand alone semichemicalChemical recoverycombustion units

None < 2.97 lb/ton BLS or90% reduction

PM HAP: particulate matter hazardous material. TGO HAP: total gaseous organic hazardous material.

Representative MACT II limits

PARAMETERS

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CANADIAN REGULATIONS

In 1992, the federal Canadian government released new Pulp and Paper Effluent Regulations under the Fisheries Act.

The PPER set limits on BOD5, TSS, and acute toxicity and had numerous reporting requirements. Regulations limiting the discharge of chlorinated dioxins and furans also went into effect in 1992 under the Canadian Environmental Protection Act (CEPA).

The CEPA and PPER regulations resulted in a massive investment to change bleaching processes and install secondary treatment before the end of 1996 at a many Canadian mills.

The first set of regulations for the pulp and paper industry, which came into force in 1971, did not limit the total amount of pollution, but rather permitted the discharge of pollutants in proportion to the production of the mill.

In 1991, the federal government responded to public pressure by introducing a regulatory scheme that required mills to implement secondary treatment systems and abide by limits to control the discharge of certain harmful pollutants, including dioxins and furans.

In 1992, the Pulp and Paper Effluent Regulations set minimum standards.

BACKGROUND

PARAMETERS

CANADIAN REGULATIONS

BACKGROUNDBACKGROUND

PARAMETERS

MAXIMUM BDO AND MAXIMUM QUANTITY OF SUSPENDED SOLIDS AUTHORIZED FOR MILLS.

WATER REGULATIONS

AIR REGULATIONS

THERE ARE NO LEGALLY BINDING CANADIAN FEDERAL OR PROVINCIAL REGULATIONS FOR AIR EMISSIONS FROM PULP MILLS FOR AMBIENT AIR QUALITY.

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Except where an authorization or transitional authorization is issued authorizing the deposit of BDO matter or suspended solids, the maximum BDO of all BDO matter and the maximum quantity of all suspended solids that may be deposited in the case of a mill is determined by:

In respect of any 24-hour period, the formula:

In respect of any month the formula:

RPRFQd *5.2*

RPRDFQm *5.1**

Where :F = is equal to a factor of 5 in respect of BDO and 7.5 in respect of suspended solids, expressed in kilograms per tonne of finished product.RPR = is the reference production rate.D = number of days in a month.

Original source: Department of Justice Canada

MAXIMUM BDO AND MAXIMUM QUANTITY OF SUSPENDED SOLIDS AUTHORIZED FOR MILLS.

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3.4.3 GENERAL REGULATIONS

Parameter Maximum valuePM 100 for recovery furnaceHydrogen sulfide 15 (for lime kilns)Total sulfur emittedSulfite mills 1.5 kg/t ADPKraft and other 1.0 kg/t ADPNitrogen oxides 2 kg/t ADP

Parameter Maximum valuepH 6--9

COD

300 mg/l and 15 kg/t for kraft andCTMP pulp mills; 700 mg/l and40kg/t of sulfite pulp mills; 10 mg/land 5kg/t of mechanical andrecycled fiber pulp; 250 mg/l forpaper mills

AOX

40 mg/l and 2 kg/t (aim for 8 mg/land 0.4 kg/t and retrofits and for 4mg/l and 0.2 kg/t for new mills)and 4 mg/l for paper mills

Total phosphorus 0.05 kg/tTotal nitrogen 0.4 kg/tTemperature < 3 C

Emissions levels for the design and operation of each project must be established throuth the environmental assessment process on the basis of country legislation and the Pollution Prevention Handbook, which establishes the following.

Air Emissions(milligrams per normal cubic meter)

Liquid effluents

Source: Pollution Prevention and Abatement Handbook 1998. World Bank Group. P 395-399

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3.5 ENVIRONMENTAL TECHNOLOGIES PULP AND PAPER INDUSTRY

In the kraft pulping process, highly emissions of reduced sulfur compounds, measured as total reduced sulfur (TRS) and including hydrogen sulfide, methyl marcaptan, dimethyl sulfide, and dimethyl disulfide, are emitted.

Sulfur oxide emissions are scrubbed with slightly alkaline solutions.

The reduced sulfur-compounds gases are collected using headers, hoods, and venting equipment.

Condensates from the digester relief condenser and evaporation of black liquor are stripped of reduced sulfur compounds.

Stripper overhead and noncondensable are incinerated in a lime kiln or a combustion unit.

Gas treatment

More information:www.jrfindia.com More information:

www.wesinc.com

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3.5 ENVIRONMENTAL TECHNOLOGIES PULP AND PAPER INDUSTRY

Wastewater treatment

To remove suspended solids:

• Neutralization• Screening• Sedimentation• Flotation

To remove the organic content:

• Activated sludge• Aerated lagoons• Anaerobic fermentation

Solid waste treatment

Solid waste treatment steps include dewatering of sludge and combustion in an incinerator, bark boiler, or fossil-fuel-fired boiler.

More information:www.sequencertech.com

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TIER 2 : STUDY CASE

This tier will demonstrate the relevance of Process Integration for specific examples of key processes in the Pulp and Paper Industry as well as in Refineries.

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STUDY CASE 1

KRAFT PULPING PROCESS

As we saw in Tier 1, the Pulping Process can be accomplished by chemical, semichemical or mechanical methods. About 80% of the wood pulp in the United States is produced through the kraft chemical pulping process.

A environmental problem associated with the kraft process is the atmospheric emission of considerable quantities of hydrogen sulfide. The serious health and environmental problems of discharging hydrogen sulfide to the atmosphere call for effective sulfur-waste reduction processes in a pulp and paper plant.

The purpose of this study case is to employ the Mass Exchange Network methodology to develop an optimal design of recycle/reuse networks for reducing the emission of hydrogen sulfide for pulp and paper plants.

(Dunn and El-Halwagi, 1993)

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Digester

DESCRIPTION OF THE KRAFT PROCESS

Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers

White Liquor Clarifier

Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

LimeContaminatedCondensate

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

Wood chips, containing ligning, cellulose and hemicellulose are added to white liquor (NaOH, Na2S, Na2CO3). The chips are cooked to solubilize the lignin.

ContaminatedCondensate

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

The solubilized lignin leaves as black liquor, leaving the cellulose and hemicellulose which are the constituents of pulp.Contaminated

Condensate

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

It is sent to the bleaching of papermaking process, depending on the end product desired.


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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

The main constituents of White Liquor are: NaOH, Na2S, Na2CO3, Na2SO4, Na2S2O3, NaCl, water.Contaminated

Condensate

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

LimeContaminatedCondensate

The Weak Black Liquor is processed through a series of evaporators to increase the solid content from 15% to 70% approximately.

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

The Strong Black Liquor is incinerated to supply energy for the pulping process and to form inorganic smelt.Contaminated

Condensate

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

Na2CO3 and Na2SContaminatedCondensate

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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

Smelt is dissolved in water to form the Green Liquor.


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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

LimeNaOH, Na2S, Na2CO3 and water.


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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

Lime (CaO) is converted to CaOH2 in presence of water.


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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

CaOH2 reacts with Na2CO3 to form NaOH and a CaCO3 as precipitant.


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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

The CaCO3 is heated to regenerate the CaO and release CO2.


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Digester


Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

Lime

NaOH, Na2S, NaCO3 and water.


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Digester

EMISSION SOURCES OF THE KRAFT PROCESS

Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Weak Black Liquor

Strong Black Liquor

SmeltGreenLiquor

Lime Mud

White Liquor

LimeAir Stripping


AirWastewater

Air Emission

Evaporators

RecoveryFurnace

AirStripping

R2

R1

R3

Three major sources in the Kraft Process are Responsible for the majority of the H2S emissions.

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INTERNAL MASS SEPARATING AGENTS

Digester

Washers

Evaporators

RecoveringFurnace

DissolvingTank

Slaker

Causticizers


Lime Kiln

CHIPS

PULP

Strong Black Liquor

Smelt

Lime Mud

White Liquor

LimeAir Stripping


AirWastewater

Air Emission

Weak Black Liquor

GreenLiquor

S2Weak Black

Liquor

S3Green Liquor

S1 White Liquor

Several Mass-Exchange operations such as absorption or adsorption can be employed to reduce the H2S emissions.

Three liquid streams that already exist in the plant (process MSAs) can be used.

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Three external MSAs will be considered potential candidates for recovering H2S:

• S4, Diethanolamine (DEA)

• S5, Activated Carbon

• S6, 30 wt% Hot potassium carbonate solution

EXTERNAL MASS SEPARATING AGENTS

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REACTIVE

MASS-EXCHANGE

NETWORK

Recovery Furnace Emissions, R1

Evaporator Emissions, R2

R3, Air Stripping Emissions

R1 R2 R3To atmosphere

White Liquor, S1

Green Liquor, S2

Black Liquor, S3

DEA, S4

Activated Carbon, S5

Hot K2CO3 solution, S6

S1

S2

S3

S4

S5

S6

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REACTIVE

MASS-EXCHANGE

NETWORK

Recovery Furnace Emissions, R1

Evaporator Emissions, R2

R3, Air Stripping Emissions

R1 R2 R3To atmosphere

White Liquor, S1

Green Liquor, S2

Black Liquor, S3

DEA, S4

Activated Carbon, S5

Hot K2CO3 solution, S6

S1

S2

S3

S4

S5

S6

Causticizer DigesterDissolving TankDigester SlakerEvaporators

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DATA FOR THE KRAFT PROCESS PROBLEM

Stream

Emissions stream

description

Gi

m3/s

yis

kmol/m3

yit

kmol/m3

R1 Recovery furnace 170.000 3.08 x 10-5 2.1 x 10-7

R2 Evaporator 0.433 8.20 x 10-5 2.1 x 10-7

R3 Air stripping 465.800 1.19 x 10-5 2.1 x 10-7

Stream Stream description

Max. available flowrate

m3/s

x js

kmol/m3

x jt

kmol/m3

S1 White liquor 0.040 3.2 x 10-1 3.10 x 100

S2 Green liquor 0.049 2.9 x 10-1 1.29 x 100

S3 Black liquor 0.100 0.2 x 10-1 1.00 x 10-1

S4 DEA 2.0 x 10-6 2 x 10-2

S5 Activated carbon 1.0 x 10-6 1.7 x 10-3

S6 Hot KCO3 solution 0.3 x 10-2 2.8 x 10-1

DATA FOR THE WASTE STREAMS

DATA FOR THE MASS SEPARATING AGENTS

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The solution of this problem will follow two different approaches:

ALGEBRAIC GRAPHICAL

DESIGN METHODOLOGY

We are looking forward the potentials for waste reduction in the Kraft Process by establishing tradeoffs between environmental and economic objectives in order to obtain the optimal configuration for a Waste-reduction system.

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APH

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INTERPRET THE RESULTS

These are the main steps that we will follow to find an optimal design of recycle/reuse networks for reducing the emission of hydrogen sulfide from a pulp and paper plant using a GRAPHICAL APPROACH.

PLOT RICH STREAM

OBTAIN PINCH POINT

PLOT LEANSTREAM

CREATEONE-TO-ONE

CORRESPONDENCE

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0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.01

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05y

Ma

ss

E

xc

ha

ng

ed

km

ol H

2S

/s

0.00544

0.00907

0.00904

R3

R2

R1

y1,2,3t y3

s y1s y2

s

GR

APH

ICA

L APPR

OA

CH

RICH COMPOSITE STREAM

The first step is to plot the mass exchanged or each rich stream versus its

composition.

Each stream is represented as an arrow whose tail corresponds to its supply composition and its head to its target composition.

The slope of the arrows will be equal to the stream flowrate and the vertical distance between the tail and the head of each arrow represents the mass of pollutant that is lost by each rich stream:

MRi=Gi(yis – yi

t), i=1,2,…,NR.

Each arrow should be placed starting with the waste stream having the lowest target composition.

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0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.01

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05

Ma

ss

E

xc

ha

ng

ed

km

ol H

2S

/s

y

The rich composite stream is obtained by applying superposition to the rich streams.

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.01

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05

Mas

s E

xch

ang

edkm

ol H

2S

/s

This rich composite stream represents the cumulative mass of the pollutant lost by all the streams.

y

RICH COMPOSITE STREAM

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The second step is to generate a one-to-one correspondence among compositions of the three waste streams and the six MSAs.

Consider a waste stream i, and and MSA, j, for which equilibrium is given by:

yi*= fi(xj*)

For any mass-exchange operation to be thermodynamically feasible, some conditions must be satisfied:

xj<xj*and/or yi>yi*

To generate the one-to-one correspondence, we use the following equation:

y=f(xj+εj)

Where εj is the minimum allowable composition difference, which means that we are adding a driving force to allow mass transfer.

A deep explanation of these concepts is given in Module 3.

ONE-TO-ONE CORRESPONDENCE

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MSA1White liquor

MSA2Green liquor

Equilibrium equation y1= 2.0402 x 10-9(10)1.1786x1 y2= 2.5763 x 10-9(10)2.8136x2

Adding the driving force

y1= 2.0402 x 10-9(10)1.1786(x1+ε1)

ε1 = 7.64y2= 2.5763 x 10-9(10)2.8136(x2+ε2)

ε2 = 3.20

Supply correspondence

y1s= 2.0402 x 10-

9(10)1.1786(0.32+7.64)

y1s= 4.91

y2s= 2.5763 x 10-

9(10)2.8136(0.29+3.20)

y2s= 17.00

Target correspondence

y1t= 2.0402 x 10-

9(10)1.1786(3.10+7.64)

y1t= 9186

y2t= 2.5763 x 10-

9(10)2.8136(1.29+3.20)

y2t= 11068

Some examples of the generation of the one-to-one correspondence are the following:

The equilibrium equation for the MSA3 (Black liquor) is:

y3=352.8 x30.71512

ONE-TO-ONE CORRESPONDENCE

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0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05 1.00E-040.32 3.1

0.29 1.29

0.02 0.01

y

x1

x2

x3

Ma

ss

E

xc

ha

ng

ed

km

ol H

2S

/s

The mass of pollutant that can be gained by each process MSA is plotted versus the composition scale

of that MSA

Mass of pollutant that can be gained by each MSA is calculated:

MSj= Ljc (xj

t – xjs) j=1,2,…,NSP

Also in this case, the arrows represent each of the process MSA, being the tail the supply composition

and the head the target composition.

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05 1.00E-04

Ma

ss

E

xc

ha

ng

ed

km

ol H

2S

/s

y

Once again, we used the diagonal rule of superposition to obtain the cumulative mass

of the pollutant gained by all the MSAs.

LEAN COMPOSITE STREAM

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0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 9.00E-05 1.00E-04

y

Ma

ss

E

xc

ha

ng

ed

km

ol H

2S

/s

Integrated Mass Exchange

PICH POINT

PinchPoint

The next step is to plot both composite streams on the same diagram.

To guarantee thermodynamic feasibility the lean composite should be above and left of the waste composite stream.

The lean composite stream can be slid down until it touches the waste composite stream. The point where the two composite streams touch is called “mass exchange pinch point”.

Lean Composite

Stream

Rich Composite

Stream

The vertical overlap between the two composite streams is the maximum amount of the pollutant that can be transferred from the waste streams to the process MSAs.

ExcessMass

Exchanged

The vertical distance referred as Excess Mass Exchanged corresponds to the capacity of the process MSAs to remove pollutants that cannot be used because of thermodynamic infeasibility.

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ALG

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CREATE ONE-TO ONECORRESPONDENCE

MASS-EXCHANGECASCADEDIAGRAM

TABLE OF EXCHANGEABLE

LOADS (TEL)

COMPOSITIONINTERVALDIAGRAM

The Algebraic Approach follows these steps:

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COMPOSITION-INTERVAL DIAGRAM (CID)

The CID is a useful tool for visualizing the mass exchange insuring thermodynamic feasibility.

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0 1 2 3 4 5 6

1

2

3

4

5

6

7

82000

17.0

210

9186

11068

11900

30800

4.86

RICH STREAMS LEAN PROCESS STREAMS

y x 109 x2 x1


1. The composition scale for the waste stream is established.2. Corresponding composition scales for the process MSAs are created.

INTER

VA

LS

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3. Each process stream is represented as a vertical arrow

The tail of each arrow represents its supply composition and its head represents its target composition.

0 1 2 3 4 5 6

82000

17.0

210

9186

11068

11900

30800

4.86

RICH STREAMS LEAN PROCESS STREAMS

y x 109 x2 x1

S3

R1

R3

R2

S1

S2

Horizontal lines are drawn at the heads and tails of the

arrows to define composition intervals.

INTER

VA

LS

1

2

3

4

6

5

7

These intervals are numerated From top to bottom.

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TABLE OF EXCHANGEABLE LOADS (TEL)

By constructing the TEL, we want to determine the mass-exchange loads of the process streams in each composition interval.

The exchangeable lead of each waste stream with passes through each interval is defined as:

Wi,kR = Gi(yk-1 – yk)

W1,1R = 0.433(0.000082-

0.0000308)W1,2

R = 117(0.0000308-0.0000119)W2,2

R = 0.433(0.0000308-0.0000119)

Wj,kS = Lj(xj.k-1 – xj,k)

W1,4S = 0.049(1.29-1.261)

W1,5S = 0.04(3.1-1.708)

W2,5S = 0.049(1.261-0.678)

WkR = Σ Wi,k

R

W2R = W1,2

R + W2,2R =

0.0022

WkS = Σ Wj,k

S

W5S = W1,5

S + W2,5S = 0.0842

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k

Residual Mass fromPreceding Interval

δ k-1

δ k

Residual Mass toSubsequent Interval

Material Balance of the key pollutant should be done for each interval.


Mass RecoveredFrom Waste

Streams

WkR

Mass TransferredTo MSAs

WkS

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A negative δk indicates that the capacity of the process leans streams at that level is greater than the load of the waste streams.

The most negative δk is the excess capacity of the process MSAs when removing the pollutant.

0

0.00002 1 0

0.00002

0.002219 2 0

0.00224

0.000477 3 0

0.00272

0.001106 4 0

0.00382

0.005235 5 0.05568

-0.04662

0 6 0.03708

-0.08370

0 7 0.01844

-0.10214

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On the revised cascade diagram the location at which the residual mass was the most negative should be zero. It corresponds to the pinch point.

PINCH POINT

0

2.22E-05 1 0

0.00002

0.002219 2 0

0.00224

0.000477 3 0

0.00272

0.001106 4 0

0.00382

0.005235 5 0.004608

0.00445

0 6 0.003068

0.00138

0 7 0.001526

0.00

The excess capacity of the process MSA should be reduced by lowering the flowrate.

The new flowrate is calculated as follows:

m3/s

Another TEL should be constructed after removing the excess capacity of the MSA.

003259.032.010.3

102.104.0

E

L

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Since the graphical approach, we saw that the pollutant could be removed just by using one MSA, so there is no need of a network. This problem has some different solutions that could be taken depending on how much we want to spend. The following figure is one solution, in which some material balance should be done in order to give the right flowrate to each absorber.

Absorber1

Absorber2

Absorber3

R1 R2 R3

White Liquor

117 m3/s3.08e-5 kmol/m3

465.8 m3/s1.19e-5 kmol/m3

0.44 m3/s8.20e-5 kmol/m3

2.1e-7kmol/m3 2.1e-7kmol/m32.1e-7kmol/m3

0.0158 m3/s0.320 kmol/m3

1.56e-4 m3/s0.320 kmol/m3

0.0158 m3/s0.320 kmol/m3

0.547 kmol/m3 0.547 kmol/m3 0.547 kmol/m3

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Absorber

R1 R2 R3

White Liquor

117 m3/s3.08e-5 kmol/m3

465.8 m3/s1.19e-5 kmol/m3

0.44 m3/s8.20e-5 kmol/m3

581.24 m3/s2.1e-7 kmol/m3 0.00326 m3/s

0.32 kmol/m3

3.10 kmol/m3

Another way of achieve this task is the following, in which the rich streams are for final disposal and can be mixed and treated as one stream, also, his arrange is more desirable in terms of costs because just one unit is needed.

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STUDY CASE 2

PETROLEUM REFINERY WASTES

A major concern in refineries is the release of phenols, although described as this, the category may include a variety of similar chemical compounds among which are polyphenols, chlorophenols, and phenoxyacids. The concern is because of their toxicity to aquatic life and the high oxygen demand they sponsor in the streams that receive it. Phenols are toxic to fish and also they can cause taste and odor problems when present in potable water.

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The next study case applies some of the skills of Process Integration to show the methodology once again and make it more understandable. This case was taken from El-Halwagi, M. “Pollution Prevention through Process Integration”, 1997.

“The process generates two major sources of phenolic wastewater; one from the catalytic cracking unit and the other from the visbreaking system. Two technologies can be used to remove phenol from R1 and R2: solvent extraction using light gas oil S1 (a process MSA) and adsorption using activated carbon S2(an external MSA). A minimum allowable composition difference, εj, of 0.01 can be used for the two MSAs.

By constructing a pinch diagram for the problem, find the minimum cost of MSAs needed to remove phenol from R1 and R2. How do you characterize the point at which both composite streams touch? Is it a true pinch point?”

PROBLEM STATEMENT

StreamG i

kg/syi

s yit

R1 8.00 0.1 0.01R2 6.00 0.08 0.01

Rich stream

StreamLc

j

kg/sxj

s xjt mj bj

cj

$/kgS1 10.00 0.01 0.02 2.00 0.00 0.00S2 0.00 0.11 0.02 0.00 0.08

MSAs

DATA

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Stabilizer

At m

osp

her i

cD

isti

llat i

on

VacuumDistillation

SweeteningUnit

Visbreaker

Hydrotreating

CatalyticCracking

Solvent Extraction and

Dewaxing

LPH and Gas

Gasoline

Naphta

Middle Distillates

Gas Oil

Lube-BaseStocks

The first step in a petroleum refinery is to preheat the crude, then it is washed with water to remove various salts.

Tre

ati

ng a

nd B

lend

ing

Refinery fuel gas

Refinery fuel oil

Industrial fuels

Asphalts

Greases

Lube oils

Aviation fuels

Diesels

Heating oils

LPG

Gasoline

Solvents

PROCESS DESCRIPTIONSweet Gasoline

Middle Distillates

Gas

Gasoline

Light Gas Oil

Wastewater, R1

Lube Oil

Waxes

Gasoline, Naphtha and Middle distillates

Fuel Oil

Asphalt

Wastewater, R2

Gas oil and heavy stocks are fed to a catalytic-cracking unit to be converted to lower molecular weight fractions. The main waste stream from this process is the condensate from stripping in the fractionating column. This condensate commonly contains ammonia, phenols and sulfides as contaminants, this has to be stripped to remove ammonia and sulfides. The bottom product of the stripper must be treated to eliminate phenols.

The light gas oil leaving the fractionator can serve as a lean-oil solvent in a phenol extraction process, being this a beneficiary mass transfer because in addition to purify water, phenols can act as oxidation inhibitors and as color stabilizers.

The main objectives of visbreaking are to reduce the viscosity and the pour points of vacuum-tower bottoms and to increase the feed stocks to catalytic cracking. The source of wastewater is the overhead accumulator on the fractionator, where water is separated from the hydrocarbon vapor. This water contains phenols, ammonia an sulfides

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12

R1

R2

y1t, y2

t y2

s y1s

Mas

s ex

chan

ged

1. PLOT THE RICH STREAM

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1. PLOT THE RICH STREAM

0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12

R1

R2

y1t, y2

t y1 y2s

Ma

ss e

xch

an

ge

d

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2. ONE-TO-ONE CORRESPONDANCE

y = m(x+ε) + b

y1s = 2(0.01+0.01) =

0.04

y1t = 2(0.02+0.01) =

0.06

y2s = 0.02(0.00+0.01) =

0.0002

y2t = 0.02(0.11+0.01) =

0.0024

To generate the one-to-one correspondence, we use the following equation:

y=f(xj+εj)

Where εj is the minimum allowable composition difference. ε j=0.01

In this case the equilibrium equation is linear:

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12

MS1

y

x1

x2S2

S1

3. PLOT THE LEAN STREAM

x1s x1

t

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12

Ma

ss e

xch

an

ge

d

y

x1

x2

0.00 0.01 0.02 0.03 0.04

1.00 2.00 3.00 4.00 5.00

Stream 1 would not be useful, since external MSAs should be used before and after using this stream. That means that this is not a true pinch point.

4. OBTAIN THE PINCH POINT

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12

Mas

s ex

chan

ged

0.1

5. INTERPRET THE RESULTS

y

Unit 1

Unit 2

Unit 3

The lean stream can be moved to remove the pollutant in another range of composition, but still three units would be needed.

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12


y

x1

x2

0.00 0.01 0.02 0.03 0.04

1.00 2.00 3.00 4.00 5.00

Unit 1

Unit 2

If the lean stream remove the pollutant since its higher composition, just 2 units are needed.

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0

0.2

0.4

0.6

0.8

1

1.2

0 0.02 0.04 0.06 0.08 0.1 0.12

Mas

s ex

chan

ged

Mass removed by Process MSA

Mass removed by External MSA

y


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•Alan P. Rossiter. Waste Minimization through Process Design. pp 43-49. McGraw Hill. 1995.

•Nicholas P. Cheremisinoff, Handbook of Pollution Prevention Practices. pp 269-313, 353-358. Marcel Dekker Inc. 2001.

•The World Bank Group. Pollution Prevention and Abatement Handbook 1998. pp 377-381, 395-399. 1998

•El-Halwagi, M. M. Pollution Prevention through Process Integration. Academic Press. 1997.

•Dunn R., El-Halwagi, M. M. Optimal Recycle/Reuse Policies for Minimizing the Wastes of Pulp and Paper Plants. J. Environ. Sci. Health, A28(1), 217-234 (1993).

•El-Halwagi, M.M., El-Halwagi, A.M., Manousiouthakis, V. Optimal Design of the Phenolization Networks for Petroleum-Refinery Wastes. Trans IChemE, Vol 70, Part B, pp 131-139. August 1992.

•Environmental Update #12, Hazardous Substance Research Centers/Southwest Outreach Program, June 2003.

•Abdallah S. Jum’ah, president and CEO, Saudi Aramco. Petroleum and social responsibility: and agenda for action. News Feature. First bread volume 20. 10 October 2002.

•Energy and Environmental Profile of the U.S. Petroleum Refining Industry. December 1998. U.S. Department of Energy, Office of Industrial Technologies

•EPA Office of Compliance Sector Notebook Project, Profile of the Petroleum Refining Industry, September 1995.

•National Pollutant Release Inventory (Canada)

•2001 Toxic Release Inventory Executive Summary (US)

•Input to the AMG Working Group Studying the Impact of Greenhouse Gas Abatement on the Competitiveness of Canadian Industries. Pulp, Paper and Paperboark Mills. Manufacturing Industries Branch. Industry Canada. March 11, 2002

•Instituto Nacional de Estadistica, Geografia e Informatica (Mexico)

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