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ENVIRONMENTAL CHALLENGES:

OVERVIEW FACING INDUSTRY

Module 2


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Purpose of Module 2

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.

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


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STRUCTURE OF MODULE 2

The module is divided into three tiers as follows:

TIER 1: Basic Concepts

TIER 2: Case Study

TIER 3: Computer-Aided Module


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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

CONTENTS

This section in broken into three sections:

1. Major Industries in North America.

2. Petroleum Industry

2.1 Driving forces, hurdles and potential.

2.2 Environmental discharges.

2.3 Regulatory issues in North America.

2.4 Best available environmental technologies for specific processes

3. Pulp and Paper Industry

3.1 Driving forces, hurdles and potential.

3.2 Environmental discharges.

3.3 Regulatory issues in North America.

3.4 Best available environmental technologies for specific processes


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1.- MAJOR INDUSTRIES

IN NORTH AMERICA


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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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More information:

Top 20 pollutants

More Statistics:

Canadian NPRI

C A N A D A

Pulp, Paper and

Paperboard mills

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



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Refineries and petroleum subproducts are included. Quantities, 2001

More information:

Top 20 pollutants

More Statistics:

TRI

U S A

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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U S A Quantities, 2001


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Gas natural Quantities, 2001Ammonia Fertilizers

More information

M E X I C O

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

Hazardous Pollutants produced by Industry

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


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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:

Pulp and Paper

Petroleum


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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..

PETROLEUM INDUSTRY


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2. Petroleum Industry 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.

2.1 Driving forces, hurdles and potential.

2.2 The Petroleum Refining Industry

2.2.1 Definition

2.2.2 Primary Products

2.2.3 Industrial Processes in the Petroleum Refining Industry

2.2.4 Refinery flow diagram

2.3 Environmental discharges.

2.3.1 Refinery air emission sources

2.3.2 Types of wastewater produced in refineries

2.3.3 Refinery Residuals

2.3.4 Environmental discharges by process

2.4 Regulatory issues in North America.

2.4.1 U.S. Regulations

2.4.2 Mexican Regulations

2.4.3 General Regulations

2.5 Best available environmental technologies for specific processes


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RELIABILITY OF SUPPLY 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.

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.

ENVIRONMENTAL

PROTECTION

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

REASONABLE PRICE

These three characteristics can act as:

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

  • DRIVING FORCES

  • HURDLES

  • POTENTIALS

2.1 DRIVING FORCES, HURDLES AND POTENTIALS

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

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

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.

First beak volume 20. 10 October 2002


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  • 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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Volatile crude prices the economic health of the United States and Mexico.

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:

Crude quality variability

Low marketing and transport profit margins

Increasing capital and operating costs of environmental compliance.


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HURDLES the economic health of the United States and Mexico.

  • 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


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The 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.

POTENTIALS

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 be the greatest potential for the country that posses them.

2.2.1 DEFINITION

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.


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

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

solvents, lubricating oils, greases, petroleum wax, petroleum jelly, asphalt 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.

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

CHEMICAL INDUSTRY

FEEDSTOCKS

FINISHED NON FUEL

PRODUCTS

FUELS


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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY

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

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

SEPARATION

CONVERSION

TREATING

BLENDING

AUXILIARY

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.

ASSOCIATED OPERATIONS

  • Atmospheric distillation

  • Vacuum distillation

  • Light ends recovery (gas processing)


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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY

SEPARATION

CONVERSION

TREATING

BLENDING

AUXILIARY

ASSOCIATED OPERATIONS

CONVERSION PROCESSES

  • Cracking (thermal and catalytic)

  • Reforming

  • Alkylation

  • Polymerization

  • Isomerization

  • Coking

  • Visbreaking

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


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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY

SEPARATION

CONVERSION

TREATING

BLENDING

AUXILIARY

ASSOCIATED OPERATIONS

TREATING 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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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY

SEPARATION

CONVERSION

TREATING

BLENDING

AUXILIARY

BLENDING/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.

ASSOCIATED OPERATIONS

  • Storage

  • Blending

  • Loading

  • Unloading


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2.2.3 INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRY

SEPARATION

CONVERSION

TREATING

BLENDING

AUXILIARY

AUXILIARY 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.

ASSOCIATED OPERATIONS

  • Boilers

  • Waste water treatment

  • Hydrogen production

  • Sulfur recovery plant


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LPH and Gas INDUSTRY

Refinery fuel gas

Gasoline

Sweet Gasoline

LPG

Stabilizer

Naphta

Gasoline

Middle Distillates

Middle Distillates

Solvents

Aviation fuels

Gas

Atmospheric

Distillation

Gasoline

Diesels

Gas Oil

Treating and Blending

Light Gas Oil

Heating oils

Lube oils

Lube-Base

Stocks

Lube Oil

Waxes

Greases

Gasoline, Naphtha and

Middle distillates

Asphalts

Vacuum

Distillation

Fuel Oil

Industrial fuels

Asphalt

Refinery fuel oil

2.2.4 REFINERY FLOW

DIAGRAM

Sweetening

Unit

Hydrotreating

Washed Crude

Catalytic

Cracking

Solvent

Extraction and

Dewaxing

Visbreaker


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2.3 ENVIRONMENTAL DISCHARGES INDUSTRY

  • 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 sources

    • Wastewater sources

    • Residuals

    • Environmental discharges by process


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COMBUSTION EMISSIONS INDUSTRY: 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.

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

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.

2.3.1 REFINERY AIR EMISSIONS SOURCES


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2.3.2 TYPES OF WASTEWATER PRODUCED IN REFINERIES INDUSTRY

  • 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.

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

  • 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 INDUSTRY

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

These residuals could be classified as follows:

  • 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).


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2.3.4 INDUSTRY DISCHARGES

LIQUID EFFLUENTS

AIR EMISSIONS

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

SOLID WASTES

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.






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

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

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.


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2.4.1 U.S. REGULATIONS purpose of reducing the environmental impacts associated with the downstream use of the product

EPA

website

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 Standards

National 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 Refineries

Subpart 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


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2.4.1 U.S. REGULATIONS purpose of reducing the environmental impacts associated with the downstream use of the product

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

To find more information:

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


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FEDERAL REQUIREMENTS AFFECTING THE REFINERY INDUSTRY purpose of reducing the environmental impacts associated with the downstream use of the product


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2.4.2 MEXICAN REGULATIONS purpose of reducing the environmental impacts associated with the downstream use of the product

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


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2.4.3 GENERAL REGULATIONS purpose of reducing the environmental impacts associated with the downstream use of the product

Solid Wastes

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.

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)

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


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2.5 ENVIRONMENTAL TECHNOLOGIES purpose of reducing the environmental impacts associated with the downstream use of the productUSED IN THE PETROLEUM INDUSTRY

Primary wastewater treatment

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

1st stage

API separator or

Corrugated plate interceptor.

More information

about the equipment

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).

2nd stage

Chemical and physical methods are utilized to separate emulsified oils from the wastewater.

More information

about the equipment

www.panamenv.com

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


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2.5 ENVIRONMENTAL TECHNOLOGIES purpose of reducing the environmental impacts associated with the downstream use of the product PETROLEUM INDUSTRY

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.

Polishing

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

Generates bio-mass waste which is treated anaerobically.

  • Activated carbon

  • Anthracite coal

  • Sand


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2.5 ENVIRONMENTAL TECHNOLOGIES purpose of reducing the environmental impacts associated with the downstream use of the product PETROLEUM INDUSTRY

Gas treatment and Sulfur Recovery

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

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

  • 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.

Process off-gas streams contain high concentrations of:

hydrogen sulfide + light refinery fuel gases.

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

Amine + hydrogen sulfide

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

hydrogen sulfide

Beaven Process

Scot Process

Wellman-Land Process

Claus Process


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2.5 ENVIRONMENTAL TECHNOLOGIES purpose of reducing the environmental impacts associated with the downstream use of the product PETROLEUM INDUSTRY

Gas treatment

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

high levels of carbon monoxide + particulates + VOCs.

www.e2t.com/E2T/app_pc05.htm

CARBON MONOXIDE BOILER

To burn carbon monoxide and VOCs

Before being released to the atmosphere

ELECTROSTATIC PRECIPITATOR OR CYCLONE SEPARATOR

To remove particulate matter

More information:

www.ppcesp.com

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.


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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:

Pulp and Paper

Petroleum


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PULP AND PAPER INDUSTRY industries which are very important for the economy and development and also are causing serious environmental problems, making a link between the three countries.

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 industries which are very important for the economy and development and also are causing serious environmental problems, making a link between the three countries.

3.1 Driving forces, hurdles and potential.

3.2 Overview of the Pulp and Paper process.

3.2.1 Different methods

3.2.2 Main steps of the process

3.3 Environmental discharges.

3.4 Regulatory issues in North America.

3.4.1 U.S. Regulations

3.4.2 Canadian Regulations

3.4.3 General Regulations

3.5 Best available environmental technologies for specific processes


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  • 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.

  • 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.

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

3.1 DRIVING FORCES


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  • 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.

3.1 HURDLES

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


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3.1 POTENTIALS market (e.g. Russia, Austria, Chile, Australia, New Zealand and Indonesia).

The Pulp and paper industry producers have some advantages:

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

  • Potential of the US and Canadian market.

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

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

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.


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3.2 OVERVIEW OF THE PULP AND PAPER PROCESS market (e.g. Russia, Austria, Chile, Australia, New Zealand and Indonesia).

CHEMICAL

MECHANICAL

Chemical 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.

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.

CHEMIMECHANICAL A combination of the previous processes.

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


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Wood yard market (e.g. Russia, Austria, Chile, Australia, New Zealand and Indonesia).

Pulping

Bleaching

Paper manufacture

3.2 OVERVIEW OF THE PULP AND PAPER PROCESS

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.

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


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3.2 OVERVIEW OF THE PULP AND PAPER PROCESS market (e.g. Russia, Austria, Chile, Australia, New Zealand and Indonesia).

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 market (e.g. Russia, Austria, Chile, Australia, New Zealand and Indonesia).

LIQUID EFFLUENTS

AIR EMISSIONS

SOLID WASTES

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

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

t:metric ton.


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

U.S. REGULATIONS

AIR REGULATIONS

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

3.4 REGULATORY ISSUES


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PARAMETERS EPA, which is a regulatory agency that establish and enforce environmental standards.

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).

BACKGROUND

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.

PARAMETERS

BACKGROUND

TOXIC 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.

GW: groundwood NI: nonintegrated

TOXIC POLLUTANTS

PARAMETERS

WATER REGULATIONS

  • Effluent Standards and Water Quality Information Advisory Committee (ES&WQIAC).

  • The Council of Environmental Quality.

  • National Commission on Water Quality

Other agencies:


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TOXIC POLLUTANTS EPA, which is a regulatory agency that establish and enforce environmental standards.

Settlement agreement toxic pollutants:


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PARAMETERS EPA, which is a regulatory agency that establish and enforce environmental standards.

  • 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.

GENERAL INFORMATION

Representative MACT II limits

  • 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.

BACKGROUND

PARAMETERS

BACKGROUND

BACKGROUND

PM HAP: particulate matter hazardous material.

TGO HAP: total gaseous organic hazardous material.

AIR REGULATIONS


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WATER REGULATIONS EPA, which is a regulatory agency that establish and enforce environmental standards.

CANADIAN REGULATIONS

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.

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.

CANADIAN REGULATIONS

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

BACKGROUND

AIR REGULATIONS

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

BACKGROUND

PARAMETERS

PARAMETERS

BACKGROUND


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

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:

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


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3.4.3 AUTHORIZED FOR MILLS. GENERAL REGULATIONS

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 AUTHORIZED FOR MILLS.PULP AND PAPER INDUSTRY

Gas treatment

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.

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

Sulfur oxide emissions are scrubbed with slightly alkaline solutions.

More information:

www.jrfindia.com

More information:

www.wesinc.com

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

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


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3.5 ENVIRONMENTAL TECHNOLOGIES AUTHORIZED FOR MILLS.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

More information:

www.sequencertech.com

Solid waste treatment

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


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TIER 2 : STUDY CASE AUTHORIZED FOR MILLS.

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 AUTHORIZED FOR MILLS.

KRAFT PULPING PROCESS

(Dunn and El-Halwagi, 1993)

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.


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DESCRIPTION OF THE KRAFT PROCESS AUTHORIZED FOR MILLS.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS AUTHORIZED FOR MILLS.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

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

PULP

Washers

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS AUTHORIZED FOR MILLS.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

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

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS AUTHORIZED FOR MILLS.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

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

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS AUTHORIZED FOR MILLS.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

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

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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

DESCRIPTION OF THE KRAFT PROCESS

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

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

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

Na2CO3 and Na2S

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

Smelt is dissolved in water to form the Green Liquor.

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

NaOH, Na2S, Na2CO3 and water.

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

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

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

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

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

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

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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DESCRIPTION OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

NaOH, Na2S, NaCO3 and water.

Causticizers

PULP

Washers

Weak Black

Liquor

Lime Mud

Slaker

Contaminated

Condensate

Lime

Evaporators

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Dissolving

Tank

Smelt


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EMISSION SOURCES OF THE KRAFT PROCESS evaporators to increase the solid content from 15% to 70% approximately.

CHIPS

Three major sources in the Kraft Process are

Responsible for the majority of the H2S emissions.

Digester

White Liquor

White Liquor

Clarifier

Lime Kiln

Causticizers

PULP

Washers

R3

Air

Emission

Weak Black

Liquor

Lime Mud

Contaminated

Condensate

Air

Stripping

Evaporators

Air

Stripping

Slaker

Lime

R2

Evaporators

Air

Wastewater

Strong Black

Liquor

Recovery

Furnace

Green

Liquor

Recovering

Furnace

Smelt

Dissolving

Tank

R1


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CHIPS evaporators to increase the solid content from 15% to 70% approximately.

S1

White Liquor

Digester

White Liquor

Clarifier

White Liquor

Lime Kiln

Causticizers

PULP

Washers

Weak Black

Liquor

Air

Emission

S2

Weak Black

Liquor

Lime Mud

Contaminated

Condensate

Air

Stripping

Slaker

Lime

S3

Green

Liquor

Evaporators

Air

Wastewater

Strong Black

Liquor

Green

Liquor

Recovering

Furnace

Smelt

Dissolving

Tank

INTERNAL MASS SEPARATING AGENTS

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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EXTERNAL MASS SEPARATING AGENTS


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Evaporator Emissions, R2 for recovering H

R3, Air Stripping Emissions

Recovery Furnace Emissions, R1

White Liquor, S1

S1

Green Liquor, S2

S2

Black Liquor, S3

S3

DEA, S4

S4

Activated Carbon, S5

S5

Hot K2CO3 solution, S6

S6

R1

R2

R3

To atmosphere

REACTIVE

MASS-EXCHANGE

NETWORK


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Evaporator Emissions, R2 for recovering H

R3, Air Stripping Emissions

Recovery Furnace Emissions, R1

Digester

Dissolving Tank

Causticizer

Evaporators

Digester

Slaker

White Liquor, S1

S1

REACTIVE

MASS-EXCHANGE

NETWORK

Green Liquor, S2

S2

Black Liquor, S3

S3

DEA, S4

S4

Activated Carbon, S5

S5

Hot K2CO3 solution, S6

S6

R1

R2

R3

To atmosphere


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DATA FOR THE KRAFT PROCESS PROBLEM for recovering H

DATA FOR THE WASTE STREAMS

DATA FOR THE MASS SEPARATING AGENTS


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DESIGN METHODOLOGY for recovering H

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.

The solution of this problem will follow two different approaches:

GRAPHICAL

ALGEBRAIC


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OBTAIN for recovering H

PINCH POINT

PLOT LEAN

STREAM

CREATE

ONE-TO-ONE

CORRESPONDENCE

PLOT RICH STREAM

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.

INTERPRET

THE RESULTS

GRAPHICAL APPROACH


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The first step is to plot the mass exchanged or each rich stream versus its 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 – yit), i=1,2,…,NR.

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

RICH COMPOSITE STREAM

GRAPHICAL APPROACH

Each arrow should be placed starting with the waste

stream having the lowest target composition.


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

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

RICH COMPOSITE STREAM

GRAPHICAL APPROACH

y

y


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ONE-TO-ONE CORRESPONDENCE the pollutant lost by all the streams.

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

GRAPHICAL APPROACH

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.


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ONE-TO-ONE CORRESPONDENCE the pollutant lost by all the streams.

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

GRAPHICAL APPROACH

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

y3=352.8 x30.71512


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LEAN COMPOSITE STREAM the pollutant lost by all the streams.

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

Once again, we used the diagonal rule of

superposition to obtain the cumulative mass

of the pollutant gained by all the MSAs.

GRAPHICAL APPROACH

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

MSj= Ljc (xjt – 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.


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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”.

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.

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.

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

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

PICH POINT

GRAPHICAL APPROACH

Lean

Composite

Stream

Excess

Mass

Exchanged

Rich

Composite

Stream

Integrated

Mass Exchange

Pinch

Point


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MASS-EXCHANGE the waste composite stream. The point where the two composite streams touch is called “mass exchange pinch point”.

CASCADE

DIAGRAM

TABLE OF

EXCHANGEABLE

LOADS (TEL)

COMPOSITION

INTERVAL

DIAGRAM

CREATE ONE-TO ONE

CORRESPONDENCE

The Algebraic Approach follows these steps:

ALGEBRAIC APPROACH


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

COMPOSITION-INTERVAL DIAGRAM (CID)

ALGEBRAIC APPROACH


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2. Corresponding composition scales for the process MSAs are created.

  • The composition scale for the waste stream is established.

COMPOSITION-INTERVAL DIAGRAM (CID)

ALGEBRAIC APPROACH

INTERVALS


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R2 created.

S3

1

R1

2

R3

INTERVALS

3

4

5

6

S2

7

S1

COMPOSITION-INTERVAL DIAGRAM (CID)

ALGEBRAIC APPROACH

These intervals are numerated

From top to bottom.

Horizontal lines are drawn at the heads and tails of the arrows to define composition intervals.

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.


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TABLE OF EXCHANGEABLE LOADS (TEL) created.

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:

ALGEBRAIC APPROACH

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)

Wi,kR = Gi(yk-1 – yk)

W1,1R = 0.433(0.000082-0.0000308)

W1,2R = 117(0.0000308-0.0000119)

W2,2R = 0.433(0.0000308-0.0000119)

WkS = Σ Wj,kS

W5S = W1,5S + W2,5S = 0.0842

WkR = Σ Wi,kR

W2R = W1,2R + W2,2R = 0.0022


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Residual Mass from created.

Preceding Interval

δ k-1

WkR

WkS

Mass Recovered

From Waste

Streams

Mass Transferred

To MSAs

δ k

Residual Mass to

Subsequent Interval

TABLE OF EXCHANGEABLE LOADS (TEL)

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

ALGEBRAIC APPROACH

k


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

TABLE OF EXCHANGEABLE LOADS (TEL)

ALGEBRAIC APPROACH

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


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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.

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.

TABLE OF EXCHANGEABLE LOADS (TEL)

ALGEBRAIC APPROACH

PINCH POINT


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R1 lowering the flowrate.

R2

R3

117 m3/s

3.08e-5 kmol/m3

0.44 m3/s

8.20e-5 kmol/m3

465.8 m3/s

1.19e-5 kmol/m3

0.547 kmol/m3

0.547 kmol/m3

0.547 kmol/m3

Absorber

1

Absorber

2

Absorber

3

2.1e-7kmol/m3

2.1e-7kmol/m3

2.1e-7kmol/m3

0.0158 m3/s

0.320 kmol/m3

1.56e-4 m3/s

0.320 kmol/m3

0.0158 m3/s

0.320 kmol/m3

White Liquor

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.


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R1 lowering the flowrate.

R2

R3

117 m3/s

3.08e-5 kmol/m3

0.44 m3/s

8.20e-5 kmol/m3

465.8 m3/s

1.19e-5 kmol/m3

3.10 kmol/m3

581.24 m3/s

2.1e-7 kmol/m3

0.00326 m3/s

0.32 kmol/m3

White Liquor

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.

Absorber


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STUDY CASE 2 lowering the flowrate.

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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Rich stream lowering the flowrate.

MSAs

PROBLEM STATEMENT

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?”

DATA


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LPH and Gas lowering the flowrate.

Refinery fuel gas

Gasoline

Sweet Gasoline

LPG

Stabilizer

Naphta

Gasoline

Middle Distillates

Middle Distillates

Solvents

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

Aviation fuels

Gas

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.

Atmospheric

Distillation

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.

Gasoline

Diesels

Gas Oil

Treating and Blending

Light Gas Oil

Heating oils

Wastewater, R1

Lube oils

Lube-Base

Stocks

Lube Oil

Waxes

Greases

Gasoline, Naphtha and

Middle distillates

Asphalts

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

Vacuum

Distillation

Fuel Oil

Industrial fuels

Asphalt

Wastewater, R2

Refinery fuel oil

PROCESS DESCRIPTION

Sweetening

Unit

Hydrotreating

Catalytic

Cracking

Solvent

Extraction and

Dewaxing

Visbreaker


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1. PLOT THE RICH STREAM lowering the flowrate.


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1. PLOT THE RICH STREAM lowering the flowrate.


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2. ONE-TO-ONE CORRESPONDANCE lowering the flowrate.

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

y=f(xj+εj)

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

In this case the equilibrium equation is linear:

y = m(x+ε) + b

y1s = 2(0.01+0.01) = 0.04

y2s = 0.02(0.00+0.01) = 0.0002

y1t = 2(0.02+0.01) = 0.06

y2t = 0.02(0.11+0.01) = 0.0024


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3. PLOT THE LEAN STREAM lowering the flowrate.

x1s

x1t


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Stream 1 lowering the flowrate. 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

y

x1

0.00

0.01

0.02

0.03

0.04

x2

1.00

2.00

3.00

4.00

5.00


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

5. INTERPRET THE RESULTS

Unit 1

Unit 2

Unit 3

y


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

5. INTERPRET THE RESULTS

Unit 1

Unit 2

y

x1

0.00

0.01

0.02

0.03

0.04

x2

1.00

2.00

3.00

4.00

5.00


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5. INTERPRET THE RESULTS composition, just 2 units are needed.

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)