2 ENVIRONMENTAL CHALLENGES: OVERVIEW FACING INDUSTRY Module 2ENVIRONMENTAL CHALLENGES:OVERVIEW FACING INDUSTRY
3 Purpose of Module 2During 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.
4 STRUCTURE OF MODULE 2The module is divided into three tiers as follows:TIER 1: Basic ConceptsTIER 2: Case StudyTIER 3: Computer-Aided Module
5 TIER 1 : BASIC CONCEPTSThis 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.
6 TIER 1 : BASIC CONCEPTS CONTENTS This section in broken into three sections:1. Major Industries in North America.2. Petroleum Industry2.1 Driving forces, hurdles and potential.2.2 Environmental discharges.2.3 Regulatory issues in North America.2.4 Best available environmental technologies for specific processes3. Pulp and Paper Industry3.1 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
8 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 :CANADAUSAMEXICO
9 C A N A D APulp, Paper andPaperboard millsCanada is the world’s largest exporter of commodity-grade pulp and paper products, making this industry one of the most important pollutant sector.More information:Top 20 pollutantsMore Statistics:Canadian NPRI
10 Top 20 Pollutants Released On Site in the Largest Quantities, 2001 C A N A D A
11 Refineries and petroleum subproducts are included. U S ARefineries 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.More information:Top 20 pollutantsMore Statistics:TRI
13 Hazardous Pollutants produced by Industry M E X I C OPetroleum industries provide raw material for the chemical industry.e.g.Gas natural Ammonia FertilizersHazardous Pollutants produced by IndustryI n Mexico, the petroleum industry development is strongly linked to the employment rate, inflation, economic growth and capital investment.More information
14 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:Pulp and PaperPetroleum
15 PETROLEUM INDUSTRYNo 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..
16 2. Petroleum Industry 2.1 Driving forces, hurdles and potential. 2.2 The Petroleum Refining IndustryDefinitionPrimary ProductsIndustrial Processes in the Petroleum Refining IndustryRefinery flow diagram2.3 Environmental discharges.Refinery air emission sourcesTypes of wastewater produced in refineriesRefinery ResidualsEnvironmental discharges by process2.4 Regulatory issues in North America.U.S. RegulationsMexican RegulationsGeneral Regulations2.5 Best available environmental technologies for specific processes
17 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:RELIABILITY OF SUPPLYAny 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.ENVIRONMENTALPROTECTIONEnvironment 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.REASONABLE PRICEThe petroleum industry is one of the most capital-intensive, high-maintenance, heavily regulated and excessively taxed industries operating worldwide.These three characteristics can act as:DRIVING FORCESHURDLESPOTENTIALSFirst beak volume October 2002
18 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 FORCESEconomic and environmental situations are involved in the development of the petroleum industry, but its final challenge must be to fulfill the society needs.
19 HURDLES Volatile crude prices 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 variabilityLow marketing and transport profit marginsIncreasing capital and operating costs of environmental compliance.
20 HURDLESThe environmental impact produced by the petroleum industry covers the effects of all and each step in the energetic cycle, which means:explotationextractionrefiningtransportationstorageconsumptionreleases
21 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.POTENTIALSSocial 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.
22 2.2 PETROLEUM REFINING INDUSTRY DEFINITIONPetroleum 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.
23 2.2.2 The primary products of this industry are divided into three categories: CHEMICAL INDUSTRYFEEDSTOCKSFINISHED NON FUELPRODUCTSFUELSmotor gasoline, diesel and distillate fuel oil, jet fuel, residual fuel oil, kerosene and cokenaphtha, ethane, propane, butane, ethylene, propylene, butylenes, butadiene, benzene, toluene and xylenesolvents, lubricating oils, greases, petroleum wax, petroleum jelly, asphalt and cokeThese 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.
24 SEPARATION CONVERSION TREATING BLENDING AUXILIARY SEPARATION PROCESSES INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRYIn 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:SEPARATIONCONVERSIONTREATINGBLENDINGAUXILIARYSEPARATION PROCESSESThese 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 OPERATIONSAtmospheric distillationVacuum distillationLight ends recovery (gas processing)
25 SEPARATION CONVERSION TREATING BLENDING AUXILIARY CONVERSION PROCESSES INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRYSEPARATIONCONVERSIONTREATINGBLENDINGAUXILIARYASSOCIATED OPERATIONSCONVERSION PROCESSESCracking (thermal and catalytic)ReformingAlkylationPolymerizationIsomerizationCokingVisbreakingInclude processes used to bread down large longer chain molecules into smaller ones by heating using catalysts.
26 SEPARATION CONVERSION TREATING BLENDING AUXILIARY TREATING PROCESSES INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRYSEPARATIONCONVERSIONTREATINGBLENDINGAUXILIARYASSOCIATED OPERATIONSTREATING PROCESSESPetroleum-treating processes are used to separate the undesirable components and impurities such as sulfur, nitrogen and heavy metals from the products.HydrodesulfurizationHydrotreatingChemical sweeteningAcid gas removalDeasphalting
27 BLENDING/COMBINATION PROCESSES INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRYSEPARATIONCONVERSIONTREATINGBLENDINGAUXILIARYBLENDING/COMBINATION PROCESSESThese 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 OPERATIONSStorageBlendingLoadingUnloading
28 SEPARATION CONVERSION TREATING BLENDING AUXILIARY AUXILIARY PROCESSES INDUSTRIAL PROCESSES IN THE PETROLEUM REFINING INDUSTRYSEPARATIONCONVERSIONTREATINGBLENDINGAUXILIARYAUXILIARY PROCESSESProcesses 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 OPERATIONSBoilersWaste water treatmentHydrogen productionSulfur recovery plant
29 Washed Crude Treating and Blending 2.2.4 REFINERY FLOW DIAGRAM LPH and GasGasolineNaphtaMiddle DistillatesGas OilLube-BaseStocksTreating and BlendingRefinery fuel gasRefinery fuel oilIndustrial fuelsAsphaltsGreasesLube oilsAviation fuelsDieselsHeating oilsLPGGasolineSolventsSweeteningUnitStabilizerAtmosphericDistillationVacuumSweet GasolineMiddle DistillatesGasGasolineLight Gas OilLube OilWaxesGasoline, Naphtha andMiddle distillatesFuel OilAsphaltHydrotreatingWashed CrudeCatalyticCrackingSolventExtraction andDewaxingVisbreaker
30 In order to answer these questions, this section will show: 2.3 ENVIRONMENTAL DISCHARGESNow, 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
31 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.
32 2.3.2 TYPES OF WASTEWATER PRODUCED IN REFINERIES 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.
33 REFINERY RESIDUALSMost 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).
34 2.3.4 DISCHARGES LIQUID EFFLUENTS AIR EMISSIONS Approximately cubic meters of wastewater per ton of crude are generated when cooling water is recycled.SOLID WASTESRefineries 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.
35 2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS PART 1
36 2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS PART 2
37 2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS PART 3
38 2.3.4 ENVIRONMENTAL DISCHARGES BY PROCESS PART 4
39 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: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.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.
40 U.S. REGULATIONSEPAwebsiteIn 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 PollutantsAt 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
41 To find more information: U.S. REGULATIONSAll these sections contain flow diagrams, where depending on the process that is being used, it must be applied certain norm.To find more information:
42 FEDERAL REQUIREMENTS AFFECTING THE REFINERY INDUSTRY
43 MEXICAN REGULATIONSIn 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 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:Then, if the complete document is needed, you can check here:
44 GENERAL REGULATIONSBesides 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 WastesWorld Band Group, Pollution Prevention and Abatement Handbook. World Bank Group. Pages
45 Corrugated plate interceptor. 2.5 ENVIRONMENTAL TECHNOLOGIES USED IN THE PETROLEUM INDUSTRYPrimary wastewater treatmentConsists on the separation of oil, water and solids in two stages.1st stageAPI separator orCorrugated plate interceptor.More informationabout the equipment2nd stageChemical and physical methods are utilized to separate emulsified oils from the wastewater.Physical methods may include the use of series of settling ponds with a long retention time, or the use of dissolved air flotation (DAF).More informationabout the equipmentChemicals, such as ferric hydroxide or aluminum hydroxide are used to coagulate impurities.
46 2.5 ENVIRONMENTAL TECHNOLOGIES PETROLEUM INDUSTRY Secondary wastewater treatmentDissolved oil and other organic pollutants may be consumed biologically.Biological treatment may require oxygen through different techniques:Activated sludge unitsTrickling filtersRotating biological contactors.PolishingSome refineries employ it as an additional stage of wastewater treatment to meet discharge limits.Generates bio-mass waste which is treated anaerobically.Activated carbonAnthracite coalSand
47 2.5 ENVIRONMENTAL TECHNOLOGIES PETROLEUM INDUSTRY Gas treatment and Sulfur RecoveryIn 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.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.Amine + hydrogen sulfideIs 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:hydrogen sulfideBeaven ProcessScot ProcessWellman-Land ProcessClaus Process
48 CARBON MONOXIDE BOILER ELECTROSTATIC PRECIPITATOR OR CYCLONE SEPARATOR 2.5 ENVIRONMENTAL TECHNOLOGIES PETROLEUM INDUSTRYGas treatmentOther 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 VOCsBefore being released to the atmosphereELECTROSTATIC PRECIPITATOR OR CYCLONE SEPARATORTo remove particulate matterMore information:Solid waste treatmentSludge 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.
49 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:Pulp and PaperPetroleum
50 PULP AND PAPER INDUSTRY 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.
51 3. Paper Industry 3.1 Driving forces, hurdles and potential. 3.2 Overview of the Pulp and Paper process.Different methodsMain steps of the process3.3 Environmental discharges.3.4 Regulatory issues in North America.U.S. RegulationsCanadian RegulationsGeneral Regulations3.5 Best available environmental technologies for specific processes
52 3.1 DRIVING FORCESThe 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.
53 3.1 HURDLESThe 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).
54 3.1 POTENTIALSThe 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.
55 CHEMIMECHANICAL A combination of the previous processes. 3.2 OVERVIEW OF THE PULP AND PAPER PROCESSThe manufacture of pulp for paper and cardboard employs different methods: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.CHEMICALCHEMIMECHANICAL A combination of the previous processes.
56 Wood yard Pulping Bleaching Paper manufacture 3.2 OVERVIEW OF THE PULP AND PAPER PROCESSThe main steps in pulp and paper manufacturing are:Wood yardThese steps are common for the three processes, although the difference is the units they use for each task.PulpingBleachingThe significant environmental impacts of the manufacture of pulp and paper result from the pulping and bleaching processes.Paper manufacture
57 CHEMICAL RECOVERY (KRAFT PULPING) 3.2 OVERVIEW OF THE PULP AND PAPER PROCESSThis table presents the purpose of each one of the processes presented before and the technologies used to reach their task.PROCESSPURPOSEMAJOR TECHNOLOGIESPULPINGConvert 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.BLEACHINGBrighten 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 MANUFACTUREPrepare stock from pulp, sheet, dewater, dry, caleder.Heat box, sheet forming table.
58 3.3 ENVIRONMENTAL DISCHARGES AIR EMISSIONSLIQUID EFFLUENTSSOLID WASTESThe principal solid wastes of concern include wastewater treatment sludge : kg/t of ADP.ADP: Air dried pulp, defined as 90% bone-dry fiber and 10% water.t:metric ton.
59 AIR REGULATIONS WATER REGULATIONS 3.4 REGULATORY ISSUES The 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.U.S. REGULATIONS
60 WATER REGULATIONSUp 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.GW: groundwood NI: nonintegratedBACKGROUNDBACKGROUNDPARAMETERSPARAMETERSPARAMETERSTOXIC POLLUTANTSTOXIC POLLUTANTSEffluent Standards and Water Quality Information Advisory Committee (ES&WQIAC).The Council of Environmental Quality.National Commission on Water QualityOther agencies:
62 AIR REGULATIONSTalking 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.PM HAP: particulate matter hazardous material.TGO HAP: total gaseous organic hazardous material.Representative MACT II limitsThe 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 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 INFORMATIONBACKGROUNDBACKGROUNDBACKGROUNDPARAMETERSPARAMETERS
63 WATER REGULATIONS AIR REGULATIONS MAXIMUM BDO AND MAXIMUM QUANTITY OF SUSPENDED SOLIDS AUTHORIZED FOR MILLS.WATER REGULATIONSAIR REGULATIONSTHERE ARE NO LEGALLY BINDING CANADIAN FEDERAL OR PROVINCIAL REGULATIONS FOR AIR EMISSIONS FROM PULP MILLS FOR AMBIENT AIR QUALITY.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 REGULATIONSCANADIAN REGULATIONSBACKGROUNDBACKGROUNDBACKGROUNDPARAMETERSPARAMETERS
64 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
65 3.4.3 GENERAL REGULATIONSEmissions 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 effluentsSource: Pollution Prevention and Abatement Handbook World Bank Group. P
66 3.5 ENVIRONMENTAL TECHNOLOGIES PULP AND PAPER INDUSTRY Gas treatmentIn 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:More information: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.
67 3.5 ENVIRONMENTAL TECHNOLOGIES PULP AND PAPER INDUSTRY Wastewater treatmentTo remove suspended solids:NeutralizationScreeningSedimentationFlotationTo remove the organic content:Activated sludgeAerated lagoonsAnaerobic fermentationMore information:Solid waste treatmentSolid waste treatment steps include dewatering of sludge and combustion in an incinerator, bark boiler, or fossil-fuel-fired boiler.
68 TIER 2 : STUDY CASEThis 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.
69 KRAFT PULPING PROCESS STUDY CASE 1 (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.
70 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorLime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
71 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWood chips, containing ligning, cellulose and hemicellulose are added to white liquor (NaOH, Na2S, Na2CO3). The chips are cooked to solubilize the lignin.WashersPULPWeak BlackLiquorLime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
72 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPThe solubilized lignin leaves as black liquor, leaving the cellulose and hemicellulose which are the constituents of pulp.Weak BlackLiquorLime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
73 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorIt is sent to the bleaching of papermaking process, depending on the end product desired.Lime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
74 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorThe main constituents of White Liquor are: NaOH, Na2S, Na2CO3, Na2SO4, Na2S2O3, NaCl, water.Lime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
75 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorThe Weak Black Liquor is processed through a series of evaporators to increase the solid content from 15% to 70% approximately.Lime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
76 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorThe Strong Black Liquor is incinerated to supply energy for the pulping process and to form inorganic smelt.Lime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
77 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorLime MudNa2CO3 and Na2SSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
78 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorLime MudSmelt is dissolved in water to form the Green Liquor.SlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
79 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorLime MudNaOH, Na2S, Na2CO3 and water.SlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
80 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorLime (CaO) is converted to CaOH2 in presence of water.Lime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
81 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPCaOH2 reacts with Na2CO3 to form NaOH and a CaCO3 as precipitant.Weak BlackLiquorLime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
82 DESCRIPTION OF THE KRAFT PROCESS The CaCO3 is heated to regenerate the CaO and release CO2.CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnCausticizersWashersPULPWeak BlackLiquorLime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
83 DESCRIPTION OF THE KRAFT PROCESS CHIPSDigesterWhite LiquorClarifierWhite LiquorLime KilnNaOH, Na2S, NaCO3 and water.CausticizersWashersPULPWeak BlackLiquorLime MudSlakerContaminatedCondensateLimeEvaporatorsStrong BlackLiquorGreenLiquorRecoveringFurnaceSmeltDissolvingTank
84 EMISSION SOURCES OF THE KRAFT PROCESS CHIPSThree major sources in the Kraft Process areResponsible for the majority of the H2S emissions.DigesterWhite LiquorWhite LiquorClarifierLime KilnCausticizersWashersPULPR3Weak BlackLiquorAirEmissionLime MudContaminatedCondensateAirStrippingEvaporatorsAirStrippingSlakerLimeR2EvaporatorsAirWastewaterStrong BlackLiquorRecoveryFurnaceGreenLiquorRecoveringFurnaceSmeltDissolvingTankR1
85 INTERNAL MASS SEPARATING AGENTS Several Mass-Exchange operations such as absorption or adsorption can beemployed to reduce the H2S emissions.Three liquid streams that already exist in the plant(process MSAs) can be used.DigesterWashersEvaporatorsRecoveringFurnaceDissolvingTankSlakerCausticizersWhite LiquorClarifierLime KilnCHIPSPULPStrong BlackLiquorSmeltLime MudLimeAirStrippingContaminatedCondensateWastewaterEmissionWeak BlackGreenS1White LiquorS2Weak BlackLiquorS3GreenLiquor
86 S4, Diethanolamine (DEA) S5, Activated Carbon EXTERNAL MASS SEPARATING AGENTSThree external MSAs will be considered potential candidates for recovering H2S:S4, Diethanolamine (DEA)S5, Activated CarbonS6, 30 wt% Hot potassium carbonate solution
89 DATA FOR THE KRAFT PROCESS PROBLEM DATA FOR THE WASTE STREAMSDATA FOR THE MASS SEPARATING AGENTS
90 DESIGN METHODOLOGY GRAPHICAL ALGEBRAIC 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:GRAPHICALALGEBRAIC
91 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.OBTAINPINCH POINTINTERPRETTHE RESULTSGRAPHICAL APPROACHPLOT LEANSTREAMCREATEONE-TO-ONECORRESPONDENCEPLOT RICH STREAM
92 RICH COMPOSITE STREAMThe first step is to plot the mass exchanged or each rich stream versus its composition.GRAPHICAL APPROACHEach arrow should be placed starting with the wastestream having the lowest target 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 – yit), i=1,2,…,NR.
93 GRAPHICAL APPROACH RICH COMPOSITE STREAM 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.yy
94 ONE-TO-ONE CORRESPONDENCE The second step is to generate a one-to-one correspondence among compositions of the three waste streams and the six MSAs.GRAPHICAL APPROACHConsider 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.
95 GRAPHICAL APPROACH ONE-TO-ONE CORRESPONDENCE Some examples of the generation of the one-to-one correspondence are the following:GRAPHICAL APPROACHMSA1White liquorMSA2Green liquorEquilibrium equationy1= x 10-9(10)1.1786x1y2= x 10-9(10)2.8136x2Adding the driving forcey1= x 10-9(10)1.1786(x1+ε1)ε1 = 7.64y2= x 10-9(10)2.8136(x2+ε2)ε2 = 3.20Supply correspondencey1s= x 10-9(10)1.1786( )y1s= 4.91y2s= x 10-9(10)2.8136( )y2s= 17.00Target correspondencey1t= x 10-9(10)1.1786( )y1t= 9186y2t= x 10-9(10)2.8136( )y2t= 11068The equilibrium equation for the MSA3 (Black liquor) is:y3=352.8 x
96 Mass of pollutant that can be gained by each MSA is calculated: LEAN COMPOSITE STREAMThe mass of pollutant that can be gained by each process MSA is plotted versus the composition scale of that MSAOnce again, we used the diagonal rule ofsuperposition to obtain the cumulative massof the pollutant gained by all the MSAs.GRAPHICAL APPROACHMass of pollutant that can be gained by each MSA is calculated:MSj= Ljc (xjt – xjs) j=1,2,…,NSPAlso in this case, the arrows represent each of the process MSA, being the tail the supply composition and the head the target composition.
97 GRAPHICAL APPROACH PICH POINT LeanCompositeStreamThe 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 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 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.ExcessMassExchangedRichCompositeStreamIntegratedMass ExchangePinchPoint
98 ALGEBRAIC APPROACH The Algebraic Approach follows these steps: MASS-EXCHANGECASCADEDIAGRAMThe Algebraic Approach follows these steps:TABLE OFEXCHANGEABLELOADS (TEL)ALGEBRAIC APPROACHCOMPOSITIONINTERVALDIAGRAMCREATE ONE-TO ONECORRESPONDENCE
99 COMPOSITION-INTERVAL DIAGRAM (CID) ALGEBRAIC APPROACHThe CID is a useful tool for visualizing the mass exchange insuring thermodynamic feasibility.
100 ALGEBRAIC APPROACH COMPOSITION-INTERVAL DIAGRAM (CID) The composition scale for the waste stream is established.2. Corresponding composition scales for the process MSAs are created.ALGEBRAIC APPROACHINTERVALS
101 ALGEBRAIC APPROACH COMPOSITION-INTERVAL DIAGRAM (CID) These intervals are numeratedFrom top to bottom.R2Horizontal lines are drawn at the heads and tails of the arrows to define composition intervals.INTERVALS1234657R1R33. Each process stream is represented as a vertical arrowS2The tail of each arrow represents its supply composition and its head represents its target composition.S1
102 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:ALGEBRAIC APPROACHWi,kR = Gi(yk-1 – yk)W1,1R = ( )W1,2R = 117( )W2,2R = 0.433( )Wj,kS = Lj(xj.k-1 – xj,k)W1,4S = 0.049( )W1,5S = 0.04( )W2,5S = 0.049( )WkR = Σ Wi,kRW2R = W1,2R + W2,2R =WkS = Σ Wj,kSW5S = W1,5S + W2,5S =
103 TABLE OF EXCHANGEABLE LOADS (TEL) Material Balance of the key pollutant should be done for each interval.Residual Mass fromPreceding Intervalδ k-1ALGEBRAIC APPROACHkMass RecoveredFrom WasteStreamsWkRMass TransferredTo MSAsWkSδ kResidual Mass toSubsequent Interval
104 TABLE OF EXCHANGEABLE LOADS (TEL) ALGEBRAIC APPROACHThe most negative δk is the excess capacity of the process MSAs when removing the pollutant.A negative δk indicates that the capacity of the process leans streams at that level is greater than the load of the waste streams.
105 TABLE OF EXCHANGEABLE LOADS (TEL) ALGEBRAIC APPROACHThe excess capacity of the process MSA should be reduced by lowering the flowrate.The new flowrate is calculated as follows:m3/sAnother 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.PINCH POINT
106 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.R1R2R3117 m3/s3.08e-5 kmol/m3465.8 m3/s1.19e-5 kmol/m30.44 m3/s8.20e-5 kmol/m32.1e-7kmol/m3m3/s0.320 kmol/m31.56e-4 m3/s0.547 kmol/m3Absorber123White Liquor
107 R1R2R3117 m3/s3.08e-5 kmol/m3465.8 m3/s1.19e-5 kmol/m30.44 m3/s8.20e-5 kmol/m3m3/s2.1e-7 kmol/m3m3/s0.32 kmol/m33.10 kmol/m3Another 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.AbsorberWhite Liquor
108 PETROLEUM REFINERY WASTES STUDY CASE 2PETROLEUM REFINERY WASTESA 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.
109 PROBLEM STATEMENTThe 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?”DATARich streamMSAs
110 Treating and Blending PROCESS DESCRIPTION LPH and GasGasolineNaphtaMiddle DistillatesGas OilLube-BaseStocksTreating and BlendingRefinery fuel gasRefinery fuel oilIndustrial fuelsAsphaltsGreasesLube oilsAviation fuelsDieselsHeating oilsLPGGasolineSolventsPROCESS DESCRIPTIONSweeteningUnitStabilizerAtmosphericDistillationVacuumSweet GasolineMiddle DistillatesGasGasolineLight Gas OilWastewater, R1Lube OilWaxesGasoline, Naphtha andMiddle distillatesFuel OilAsphaltWastewater, R2HydrotreatingThe first step in a petroleum refinery is to preheat the crude, then it is washed with water to remove various salts.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.CatalyticCrackingSolventExtraction andDewaxingThe 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 sulfidesVisbreaker
113 y = m(x+ε) + b y=f(xj+εj) y1s = 2(0.01+0.01) = 0.04 2. ONE-TO-ONE CORRESPONDANCETo generate the one-to-one correspondence, we use the following equation:y=f(xj+εj)Where εj is the minimum allowable composition difference. εj=0.01In this case the equilibrium equation is linear:y = m(x+ε) + by1s = 2( ) = 0.04y2s = 0.02( ) =y1t = 2( ) = 0.06y2t = 0.02( ) =
115 4. OBTAIN THE PINCH POINT y x1 x2 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.yx10.000.010.020.030.04x21.002.003.004.005.00
116 5. INTERPRET THE RESULTSUnit 1Unit 2The lean stream can be moved to remove the pollutant in another range of composition, but still three units would be needed.Unit 3y
117 5. INTERPRET THE RESULTS y x1 x2 Unit 1If the lean stream remove the pollutant since its higher composition, just 2 units are needed.Unit 2yx10.000.010.020.030.04x21.002.003.004.005.00
118 5. INTERPRET THE RESULTS y Mass removed by Process MSA Mass removed by External MSAy
119 Alan P. Rossiter. Waste Minimization through Process Design. pp 43-49 Alan P. Rossiter. Waste Minimization through Process Design. pp McGraw HillNicholas P. Cheremisinoff, Handbook of Pollution Prevention Practices. pp , Marcel Dekker IncThe World Bank Group. Pollution Prevention and Abatement Handbook pp ,El-Halwagi, M. M. Pollution Prevention through Process Integration. Academic PressDunn R., El-Halwagi, M. M. Optimal Recycle/Reuse Policies for Minimizing the Wastes of Pulp and Paper Plants. J. Environ. Sci. Health, A28(1), (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 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 October 2002.Energy and Environmental Profile of the U.S. Petroleum Refining Industry. December U.S. Department of Energy, Office of Industrial TechnologiesEPA 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, 2002Instituto Nacional de Estadistica, Geografia e Informatica (Mexico)