ENVIRONMENTAL CHALLENGES OVERVIEW FACING THE PETROLEUM INDUSTRY:

ENVIRONMENTAL CHALLENGES OVERVIEW FACING THE PETROLEUM INDUSTRY:
MODULE #2 ENVIRONMENTAL CHALLENGES OVERVIEW FACING THE PETROLEUM INDUSTRY: Sustainable Development and Industrial Practice

PURPOSE OF MODULE This module is part of a system of modules developed to promote the understanding and use of process integration in engineering curricula. Process Integration is the synthesis of process control, process engineering and process modeling and simulation into tools that can deal with the large quantities of operating data now available from process information systems. Once synthesized the tools can then be applied to various challenges facing industry and even challenges beyond the realm of industry. 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. Petroleum refineries are used as proof of the concept.

STRUCTURE OF MODULE 2 Tier 1 Foundation Elements
The module is divided into three tiers as follows: Tier 1 Foundation Elements Tier 2 Case Study Elements Tier 3 Open-Ended Problem

Tier 1 Foundation Elements

Tier 1 Foundation Elements
Role of Process Integration in Facing the Challenge, Available Tools, Tools to be Developed Basic Processes of a Refinery Classification of Refinery Wastes Quantification of Waste Discharges Best Available Technologies for Refineries Regulatory Issues for Refineries in North America Driving Forces, Hurdles, & Potential for Environmental Issues

Role of Process Integration in Facing the Challenge, Available Tools, Tools to be Developed Basic Processes of a Refinery ion of Refinery Classification of Refinery Wastes Quantification of Waste Discharges Best Available Technologies for Refineries Regulatory Issues for Refineries in North America Driving Forces, Hurdles, & Potential for Environmental Issues

ROLE OF PROCESS INTEGRATION IN FACING THE CHALLENGE, AVAILABLE TOOLS, TOOLS TO BE DEVELOPED

Role of Process Integration in Facing the Challenge, Available Tools, Tools to be Developed 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 tier will introduce the basic concepts of industrial refining including refinery processes, identifying refinery wastes, and exploring technologies that deal with refinery wastes.

BASIC PROCESSES OF A REFINERY
Tier 1 Foundation Elements BASIC PROCESSES OF A REFINERY

Basic Processes of a Refinery 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.

Basic Processes of a Refinery 2.1 Separation Processes 2.2 Conversion Processes 2.3 Treatment Processes 2.4 Blending Processes 2.5 Auxiliary Processes

Basic Processes of a Refinery 2.1 Separation Processes These processes involve separating the different fractions of hydrocarbon compounds that make up crude oil based on their boiling point differences. Additional processing of these fractions is usually needed to produce final products to be sold within the market.

Basic Processes of a Refinery 2.1 Separation Processes Absorption Adsorption Crystallization Distillation Extraction Other Separation Processes Figure 1. Separation of Crude oil into fractions by fractional distillation Diagram drawn by Theresa Knott

Basic Processes of a Refinery 2.1 Separation Processes Examples: Distillation Atmospheric distillation (Primary Distillation) Vacuum distillation (Secondary Distillation) Absorption Light ends recovery (Gas processing) Extraction Solvent extraction (Deasphalting)

Basic Processes of a Refinery 2.2 Conversion Processes Include processes used to break down long chain molecules into smaller ones by heating using catalysts.

Basic Processes of a Refinery 2.2 Conversion Processes Thermal Processes Catalytic Processes Property Improvement Processes

Basic Processes of a Refinery 2.2 Conversion Processes Examples: Cracking (thermal and catalytic) Catalytic Reforming Alkylation Polymerization Isomerization Coking Visbreaking

Basic Processes of a Refinery 2.3 Treating Processes Petroleum-treating processes are used to separate the undesirable components and impurities such as sulfur, nitrogen and heavy metals from the products. Finishing Processes Treatment Processes

Basic Processes of a Refinery 2.3 Treating Processes Examples Hydrotreatment/hydrogenation Chemical Sweetening Hydrodesulfurization Acid gas removal Gas Treatment

Basic Processes of a Refinery 2.4 Blending Processes These are used to create mixtures with the various fractions to produce a desired final product, some examples of this are lubricating oils, asphalt, or gasoline with different octane ratings.

Basic Processes of a Refinery 2.4 Blending Processes Storage Blending Loading Unloading

Basic Processes of a Refinery 2.5 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.

Basic Processes of a Refinery 2.5 Auxiliary Processes Boilers Waste water treatment Stack gas processing Hydrogen production Sulfur recovery plant

CLASSIFICATION OF REFINERY WASTES View of the Shell/Valero Martinez oil refinery Image taken July 20, 2004 by User:Leonard G.

Classification of Refinery Wastes Air Emissions Wastewater Residuals Total Environmental Discharges by Process

Classification of Refinery Wastes 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. WASTEWATER SYSTEM EMISSIONS from tanks, ponds and sewer system drains.

Classification of Refinery Wastes Air Emissions Sources (Continued) 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 TANK EMISSIONS released when product is transferred to and from storage tanks.

Classification of Refinery Wastes Wastewater Types 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.

Classification of Refinery Wastes Residuals Types 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).

QUANTIFICATION OF WASTE DISCHARGES
Tier 1 Foundation Elements QUANTIFICATION OF WASTE DISCHARGES

Quantification of Waste Discharges Air Emissions Solid Wastes Liquid Effluents

Quantification of Waste Discharges Air Emissions Table 1. Average rate of air pollutants in crude Source: 3. Pollution Prevention and Abatement Handbook

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

Quantification of Waste Discharges Liquid Effluent Approximately cubic meters of wastewater per ton of crude are generated when cooling water is recycled. The maximum effluent concentration of nitrogen (total) may be up to 40 mg/l in processes that include hydrogenation The effluent should result in a temperature increase of no more than 3oC at the edge of the zone where initial mixing and dilution take place. Where the zone is not defined, use 100 meters from the point of discharge, provided there are no sensitive ecosystems within this range. Table 2. Average rate of liquid pollutants in crude Source: 3. Pollution Prevention and Abatement Handbook

BEST AVAILABLE TECHNOLOGIES FOR REFINERIES
Tier 1 Foundation Elements BEST AVAILABLE TECHNOLOGIES FOR REFINERIES

Best Available Technologies for Refineries While it is important to reduce the various types of refinery emissions and discharges (air, liquid, and solid), air emissions are generally of particular interest and concern There are various Best Available Technologies (BAT’s) that are available for the reduction of air emissions such as NOx, SOx, and VOCs.

Best Available Technologies for Refineries NOx Flue Gas Recirculation Low NOx Burners Ultra-Low NOx Burners Selective Catalytic Reduction Selective Non-Catalytic Reduction Combination System

Tier 1 Foundation Elements Tier 1 Foundation Elements
Best Available Technologies for Refineries NOx Example-Low NOx Burners Low-NOx burner (LNB) technology utilizes advanced burner design to reduce NOx formation through the restriction of oxygen, flame temperature, and/or residence time. The two general types of low NOx burners are staged fuel and staged air burners. Staged fuel LNBs separate the combustion zone into two regions. The first region is a lean primary combustion region where the total quantity of combustion air is supplied with a fraction of the fuel. Combustion in the primary region (first stage) takes place in the presence of a large excess of oxygen at substantially lower temperatures than a standard burner.

Best Available Technologies for Refineries NOx Example-Low NOx Burners In the second region (second stage), the remaining fuel is injected and combusted with any oxygen left over from the primary region. In the secondary combustion region, fuel/oxygen are mixed diffusively (rather than turbulently) which maximizes the reducing conditions. This technique inhibits the formation of thermal NOx, but has little effect on fuel NOx. Thus staged fuel LNBs are particularly well suited for boilers and process heaters burning process and natural gas which generate higher thermal NOx. For fuel oil fired boilers and process heaters the staged air LNBs are generally preferred, given the higher nitrogen content usually present in fuel oils. By increasing residence times staged air LNBs provide reducing conditions which has a greater impact on fuel NOx than staged fuel burners. The estimated NOx control efficiency for LNBs where applied to petroleum refining fuel burning equipment is generally around 40 percent.

Best Available Technologies for Refineries NOx Example-Low NOx Burner Figure 2. Low NOx Burner Equipment Source:

Best Available Technologies for Refineries NOx Example-Low NOx Burner Figure 3. Low NOx Burner Equipment Source:

Best Available Technologies for Refineries SOx Advanced Flue Gas Desulfurization Dry Flue Gas Desulfurization (Spray Dryer Absorption)

Best Available Technologies for Refineries SOx Example-Advanced Flue Gas Desulfurization The Advanced Flue Gas Desulfurization process accomplishes SO2 removal in a single absorber which performs three functions: prequenching the flue gas, absorption of SO2, and oxidation of the resulting calcium sulfite to wallboard-grade gypsum. Incoming flue gas is cooled and humidified with process water sprays before passing to the absorber. In the absorber, two tiers of fountain-like sprays distribute reagent slurry over polymer grid packing that provides a large surface area for gas/liquid contact. The gas then enters a large gas/liquid disengagement zone above the slurry reservoir in the bottom of the absorber and exits through a horizontal mist eliminator.

Best Available Technologies for Refineries SOx Ejemplo-Desulfuración Avanzada de Gas de Chimenea As the flue gas contacts the slurry, the sulfur dioxide is absorbed, neutralized, and partially oxidized to calcium sulfite and calcium sulfate. The overall reactions are shown in the following equations: CaCO3 + SO2 → CaSO3 • 1/2 H2O + CO2 CaSO3 •1/2 H2O + 3H2O + O2 → 2 CaSO4 • 2 H2O After contacting the flue gas, slurry falls into the slurry reservoir where any unreacted acids are neutralized by limestone injected in dry powder form into the reservoir. The primary reaction product, calcium sulfite, is oxidized to gypsum by the air rotary spargers, which both mix the slurry in the reservoir and inject air into it. Fixed air spargers assist in completing the oxidation. Slurry from the reservoir is circulated to the absorber grid.

Best Available Technologies for Refineries SOx Example-Advanced Flue Gas Desulfurization A slurry stream is drawn from the tank, dewatered, and washed to remove chlorides and produce wallboard quality gypsum. The resultant gypsum cake contains less than 10 percent water and 20 ppm chlorides. The clarified liquid is returned to the reservoir, with a slipstream being withdrawn and sent to the wastewater evaporation system for injection into the hot flue gas ahead of the electrostatic precipitator. Water evaporates and dissolved solids are collected along with the flash for disposal or sale.

Best Available Technologies for Refineries SOx Example-Advanced Flue Gas Desulfurization Figure 4. Advanced Flue Gas Desulfurization Source: 11.

Best Available Technologies for Refineries VOCs Adsorption Systems Condensation Systems Thermal Oxidation Systems Flares Steam Stripping Tank Seals

Best Available Technologies for Refineries VOCs Example-Steam Stripping Refinery wastewater streams containing VOCs can emit these compounds to the atmosphere unless they are removed from the wastewater. Steam stripping has been employed for separation of these compounds from refinery wastewater. It is essentially distillation to volatize the VOCs in order to separate them from the wastewater. The volatized compounds are then condensed and may be recycled within the refinery complex.

Best Available Technologies for Refineries VOCs Example-Steam Stripping Figure 5. Steam Stripping Source: 9.

REGULATORY ISSUES FOR REFINERIES IN NORTH AMERICA
Tier 1 Foundation Elements REGULATORY ISSUES FOR REFINERIES IN NORTH AMERICA

Regulatory Issues For Refineries in North America CANADA CAC Emissions SIC and NAICS Codes Air Emissions Statistics

Regulatory Issues For Refineries in North America CANADA CAC Emissions The emissions of various air pollutants that affect public health and contribute to air pollution problems such as smog are tracked by Environment Canada. These emissions originate from a number of sources located across the country which include industrial production, fuel combustion, transportation vehicles, incineration, paved and unpaved roads, forest fires, etc. Emission summaries for selected air pollutants such as Total Particulate Matter (TPM), Particulate Matter less than or equal to 10 Microns (PM10), Particulate Matter less than or equal to 2.5 Microns (PM2.5), Sulphur Oxides (SOx), Nitrogen Oxides (NOx), Volatile Organic Compounds (VOCs), Carbon Monoxide (CO) and Ammonia (NH3) are available on the Environment Canada website. These pollutants are also referred to as Criteria Air Contaminants (CAC).

Regulatory Issues For Refineries in North America CANADA SIC and NAICS Codes The Standard Industrial Classification (SIC) was originally developed in the 1930's to classify establishments by the type of activity in which they are primarily engaged and to promote the comparability of establishment data describing various facets of the U.S. economy. NAICS industries are identified by a 6-digit code, in contrast to the 4-digit SIC code. The longer code accommodates the larger number of sectors and allows more flexibility in designating subsectors. It also provides for additional detail not necessarily appropriate for all three NAICS countries. The international NAICS agreement fixes only the first five digits of the code. The sixth digit, where used, identifies subdivisions of NAICS industries that accommodate user needs in individual countries. Thus, 6-digit U.S. codes may differ from counterparts in Canada or Mexico, but at the 5-digit level they are standardized.

Regulatory Issues For Refineries in North America CANADA SIC and NAICS Codes Three-country comparability of the North American Industry Classification System (NAICS) 2002: NAICS 2002 has a five-digit classification structure, with a six-digit structure for national industries. With some important exceptions, it provides a set of standard 5-digit industries that describe the industrial structure and composition of the Canadian, United States and Mexican economies at selected levels of aggregation where agreement occurred among the three countries on a compatible classification. Below the agreed-upon level of compatibility each country has added additional detailed six-digit industries, as necessary to meet national needs, provided that this additional detail aggregates to the NAICS level. Some useful links for more about these codes

Regulatory Issues For Refineries in North America USA Environmental Laws Affecting the Petroleum Industry Clean Air Act Clean Water Act Resource Conservation and Recovery Act Safe Drinking Water Act Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Emergency Planning and Community Right to Know Act Oil Pollution Act OSHA Toxic Substances Control Act Energy Policy Act

Regulatory Issues For Refineries in North America USA Environmental Laws Affecting the Petroleum Industry Clean Air Act (1970)-National Ambient Air Quality Standards (NAAQS) for six constituents; new more stringent standards for ozone under NAAQS (more than doubles non-attainment areas); new standards under NAAQS that require control of particulate matter of 2.5 microns or smaller; lead-free gasoline; low-sulfur fuel; reformulated gasoline; hazardous air pollutants; visibility requirements; New Source Performance Standards Clean Air Act (1990 Amendments)-Oxygenated Fuels Program for “nonattainment areas”; low-sulfur highway diesel fuel; Reformulated Fuels Program; Leaded Gasoline Removal Program; Reid Vapor Pressure regulations to reduce VOCs and other ozone precursors; New Source Review for new or expanded facilities or process modifications; National Emission Standards for Hazardous Air Pollutants; Risk Management Plans; National Ambient Air Quality Standards

Regulatory Issues For Refineries in North America USA Environmental Laws Affecting the Petroleum Industry Clean Water Act-Regulates discharges and spills to surface waters; wetlands Resource Conservation and Recovery Act-Standards and regulations for handling and disposing of solid and hazardous wastes Safe Drinking Water Act-Regulates disposal of wastewater in underground injection wells Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)-“Superfund”; liability for CERCLA hazardous substances could apply to wastes generated during refining; includes past releases; exempts petroleum and crude oil; provides for natural resource damages

Regulatory Issues For Refineries in North America USA Environmental Laws Affecting the Petroleum Industry Emergency Planning and Community Right to Know Act (EPCRA)-Requires annual reporting on the releases and transfers of listed toxic chemicals (§313); reporting presence of “extremely hazardous substances” in excess of threshold planning quantities (§302); reporting certain releases of CERCLA hazardous substances and EPCRA extremely hazardous substances (§304); presence of hazardous chemicals over specified thresholds, to state and local governments and local fire departments, to help local government to respond in case of spills or accidental releases (§§ ) Oil Pollution Act (1990) and Spill Prevention Control and Countermeasure Plans-Liability against facilities that discharge oil to navigable waters or pose a threat of doing so

Regulatory Issues For Refineries in North America USA Environmental Laws Affecting the Petroleum Industry Occupational Safety and Health Act (OSHA)-Health Standards and Process Safety Management Rules; Limits benzene and other chemical exposures in the workplace; safety plans required in all refineries Toxic Substances Control Act (TSCA)-Collection of data on chemicals for risk evaluation, mitigation and control; can ban chemicals that pose unreasonable risks Energy Policy Act-Use of alternative fuels for transportation; efficiency standards for new federal buildings, buildings with federally backed mortgages, and commercial and industrial equipment; R&D programs for technologies; will reduce demand for petroleum products

Regulatory Issues For Refineries in North America MEXICO 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 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: If the complete document is needed it can be obtained at the following site:

DRIVING FORCES, HURDLES, AND POTENTIAL FOR ENVIRONMENTAL ISSUES
Tier 1 Foundation Elements DRIVING FORCES, HURDLES, AND POTENTIAL FOR ENVIRONMENTAL ISSUES

Driving Forces Hurdles and Potential for Environmental Issues The petroleum refining industry is a strong contributor to the economic health of the United States and Mexico. Oil well near Sarnia, Ontario For Mexico, this industry has become a vital part of the national economy, it is a primary 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.

Tier 2 Case Study Elements

Tier 2 Case Study Earlier it was stated that process integration is a systematic approach to solving environmental problems. The following case study utilizes a typical petroleum refinery to establish preliminary material and energy balances and ultimately develop preliminary targets for environmental discharges using process integration. We will then identify priority pollutants, quantify energy-related issues and their relation to pollution.

Tier 2 Case Study Preliminary Material and Energy Balances for a typical refinery Priority Pollutants Quantification of Energy-Related Issues in Regards to Pollution Preliminary Targets for Environmental Discharges Using Process Integration

Tier 2 Case Study Typical Refinery
Figure 6. Schematic of Mexican Petroleum Refining Process Source: E Aguuilar R. Revista del IMIQ. Año XLIII, Vol. 1-2, Enero Febrero 2002

Tier 2 Case Study Overall Material Balance 223,992 BPCD Refinery
Preliminary Material and Energy Balances for a typical refinery Overall Material Balance LPG (11,161) NC4 (5,844) Crude Oil (223,992) Naphtha (11,276) 223,992 BPCD Refinery Gasoline (103,000) Refinery C5-(899) Xylenes (11,267) Benzene (3,165) Kerosine/Jet (21,200) Diesel (41,200) Residual Fuel Oil (13,500) Coke (3,278) The above overall material balance is for a U.S. Gulf Coast Refinery and 223,992 BPCD (barrels per calendar day) of Maya Crude Oil For more specific material balances and process descriptions, see SRI Report No. 215 Petroleum Refining Profitability Figure 7. Material Balance for a U.S. Gulf Coast Refinery, 223,992 BPCD of Maya Crude Source: SRI Report No. 215 Petroleum Refining Profitability

Tier 2 Case Study Priority Pollutants
Preliminary Material and Energy Balances for a typical refinery Priority Pollutants Quantification of Energy-Related Issues in Regards to Pollution Preliminary Targets for Environmental Discharges Using Process Integration

Tier 2 Case Study Pemex Refinancíon (PR) Priority Pollutants
Table 3. Pemex Refinery Emissions and Discharges Air emissions are the major contributors to environmental pollution contributing 90.4% in 2001 and 76.0% in 2002.

Table 4. Pemex Refinery Air Emissions Of the air emissions, the priority pollutants are SOX contributing 81.8% in 2001 and 78.9% in 2002. Volatile Organic Compounds are the second major contributors to air emissions accounting for approximately 8% (7.98% in 2001 and 8.15% in 2002). 1Excluding VOCs (already accounted for in total organic compounds (TOCs).

Table 5. Pemex Refinery Discharges to Water Of the discharges to water, the priority pollutants are the total suspended solids contributing 47.9% in 2001 and 57.2% in 2002. Note that there is an overall decrease in total discharges to water in 2002 including a decrease in total suspended solids the increase in percentage in 2002 is reflective of the overall decrease in discharges.

Table 6. Pemex Refinery Hazardous Waste Greenhouse gases, namely CO2 emissions, are the major source of hazardous wastes. Carbon Dioxide emissions steadily declined from 1999 to 2001 ( millions of tons, millions of tons). Total generation of non-greenhouse wastes accounted for a significant portion of total emissions and discharges (7.90% in 2001 and 20.53% in 2002).

Table 7. Pemex Refinery Hydrocarbon Spills Hydrocarbon spills on land account for the majority of hydrocarbon spills and leaks.

Tier 2 Case Study Energy Use
Quantification of Energy-Related Issues in Regards to Pollution Energy Use Table 8. Estimated Energy Use by Refining Process

Tier 2 Case Study Quantification of Energy-Related Issues in Regards to Pollution Table 9. Air Emission Factors by Process

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration 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.

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration 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?”

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Data Rich stream MSAs Tables 10 & 11. Data for Phenolic Wastewater Problem

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration The Process LPH and Gas Gasoline Naphta Middle Distillates Gas Oil Lube-Base Stocks Treating and Blending Refinery fuel gas Refinery fuel oil Industrial fuels Asphalts Greases Lube oils Aviation fuels Diesels Heating oils LPG Gasoline Solvents Sweetening Unit Sweet Gasoline Middle Distillates Gas Gasoline Light Gas Oil Wastewater, R1 Lube Oil Waxes Gasoline, Naphtha and Middle distillates Fuel Oil Asphalt Wastewater, R2 Stabilizer Atmospheric Distillation Vacuum Hydrotreating Catalytic Cracking Solvent Extraction and Dewaxing Visbreaker Figure 8. Petroluem Refining Process

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Process Description The 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.

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Process Description The light gas oil leaving the fractionator can serve as a lean-oil solvent in a phenol extraction process. This can be a beneficiary mass transfer because in addition to purifying water, phenols can act as oxidation inhibitors and as color stabilizers. The main objectives of visbreaking are to reduce the viscosity and the pour points of vacuum-tower bottoms and to increase the feed stocks to catalytic cracking. The source of wastewater is the overhead accumulator on the fractionator, where water is separated from the hydrocarbon vapor. This water contains phenols, ammonia an sulfides.

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Rich Stream Plot Figure 10. Plot of Rich Stream

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Rich Stream Plot Figure 11. Plot of Rich Stream

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration One-To-One Correspondence 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( ) = y2s = 0.02( ) = y1t = 2( ) = y2t = 0.02( ) =

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Lean Stream Plot Figure 12. Plot of Lean Stream

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Obtain A Pinch-Point Figure 13. Plot of Lean Stream with Pinch Point Indicated

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Obtain A Pinch-Point 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 (see Figure 13).

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Interpret Results Figure 14. Shifting the Lean Stream

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Interpret Results The lean stream can be moved to remove the pollutant in another range of composition, but still three units would be needed (see Figure 14).

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Interpret Results Figure 15. Shifting the Lean Stream

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Interpret Results If the lean stream is moved to a still higher composition, it can remove the pollutant and just 2 units are needed (see Figure 15).

Tier 2 Case Study Preliminary Targets for Environmental Discharges Using Process Integration Interpret Results Mass removed by Process MSA Mass removed by External MSA y Figure 16. Mass Removed by Process MSA and External MSA

Tier 3 Open-Ended Problem

Tier 3 Open-Ended Problem
Utilizing Case Study There are 6 refineries in Mexico A typical refinery (See Figure 6.)produces roughly 250,000 BPD. The major products as shown in Figure 8 are heavy fuel oil, gasoline, diesel, kerosine, and LPG.

Utilizing Case Study Heavy Fuel Oil (33.3%) Gasoline (33.0%) 250,000 BPD Refinery Oil Diesel (22.0%) Kerosine (6.6%) LPG (5.1%) Figure 17. Overall mass balance for a typical Mexican refinery. Note: Keep in mind that in a detailed overall refinery balance, there are other outputs besides the desired products.

Utilizing Case Study Below is an example of an open ended problem that might be faced in industry Consider the example of a typical Mexican petroleum refinery (figure 6). Based on the assumption that no low NOx burners are used and that boilers with no combustion cleaning process (i.e. for SO2 and NOx) are also used and using Tables 4-8, determine the amount of NO2 discharged from a typical refinery. Compare this amount to the standards presented in Table 1. Utilize the mass integration techniques presented in Tier 2 to meet the NO2 emissions specifications.

Acronyms TSP-Total Suspended Particles TOC-Total Organic Compound
VOC-Volatile Organic Compound O&G-Oils and Greases TSS-Total Suspended Solids MMBCOE-Million Barrells of Crude Oil Equivalent

End of Module CONGRATULATIONS!!! This is the end of Module #2.
Please submit your report to your professor for grading.

Resources Rossiter, Alan P. Waste Minimization through Process Design. MacGraw Hill Cheremisinoff, Nicholas P. Handbook of Pollution Prevention Practices. Marcell Dekker Inc The World Bank Group. Pollution Prevention and Abatement Handbook 1998. El-Halwagi, M.M. Pollution Prevention Through Process Integration. Academic Press Environmental Update #12, Hazardous Substance Research Centers/Southwest Outreach Program, June Energy and Environmental Profile of the U.S. Petroleum Industry. December U.S. Department of Energy, Office of Industrial Technologies. EPA Office of Compliance Sector Notebook Project, Profile of the Petroleum Refining Industry, September 1995.

Resources http://www.jaeger.com/brochure/steam%20stripping.pdf
Midwest Regional Planning Organization (RPO), Petroleum Refinery Best Available Retrofit Technology (BART) Engineering Analysis, Prepared for: The Lake Michigan Air Directors Consortium (LADCO), Prepared by: MACTEC Federal Programs / MACTEC Engineering and Consulting, Inc.(MACTEC), March 30, 2005. Revista Del IMIQ. Enero Febrero Instituto Mexicano de Ingenieros Químicas A.C. ISSN /Año XLIII, Vol 1-2. *PEMEX Sustainable Development: Safety, Health and Environment, Report 2001. **PEMEX Sustainable Development: Safety, Health and Environment, Report

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