ENVIRONMENTAL CHALLENGES OVERVIEW FACING THE PETROLEUM INDUSTRY:
MODULE #2
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
Tier 2 Case Study Elements
Tier 3 Open-Ended Problem
The module is divided into three tiers as follows:
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
Tier 1 Foundation Elements
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
Tier 1 Foundation Elements
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.
Tier 1 Foundation ElementsRole of Process Integration in Facing the Challenge, Available Tools, Tools to be Developed
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
Tier 1 Foundation Elements
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
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.
Tier 1 Foundation Elements
DEFINITION
Basic Processes of a Refinery
Tier 1 Foundation Elements 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
Tier 1 Foundation Elements
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
Tier 1 Foundation Elements
2.1 Separation Processes Absorption Adsorption Crystallization Distillation Extraction Other Separation Processes
Basic Processes of a Refinery
Figure 1. Separation of Crude oil into fractions by fractional distillation
Diagram drawn by Theresa Knott
Tier 1 Foundation Elements
2.1 Separation ProcessesExamples: 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.
Tier 1 Foundation ElementsBasic Processes of a Refinery
2.2 Conversion Processes Thermal Processes Catalytic Processes Property Improvement Processes
Tier 1 Foundation ElementsBasic Processes of a Refinery
2.2 Conversion ProcessesExamples: Cracking (thermal and catalytic) Catalytic Reforming Alkylation Polymerization Isomerization Coking Visbreaking
Tier 1 Foundation ElementsBasic 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
Tier 1 Foundation ElementsBasic Processes of a Refinery
2.3 Treating Processes
Examples Hydrotreatment/hydrogenation Chemical Sweetening Hydrodesulfurization Acid gas removal Gas Treatment
Tier 1 Foundation ElementsBasic 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.
Tier 1 Foundation ElementsBasic Processes of a Refinery
2.4 Blending Processes Storage Blending Loading Unloading
Tier 1 Foundation ElementsBasic Processes of a Refinery
2.5Auxiliary 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.
Tier 1 Foundation ElementsBasic Processes of a Refinery
2.5 Auxiliary Processes Boilers Waste water treatment Stack gas processing Hydrogen production Sulfur recovery plant
Tier 1 Foundation ElementsBasic Processes of a Refinery
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
CLASSIFICATION
OF REFINERY
WASTES
Tier 1 Foundation Elements
View of the Shell/Valero Martinez oil refinery
Image taken July 20, 2004 by User:Leonard G.
Air Emissions
Wastewater
Residuals
Total Environmental Discharges by Process
Tier 1 Foundation ElementsClassification of Refinery Wastes
Air EmissionsSources
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.
Tier 1 Foundation ElementsClassification of Refinery Wastes
Air EmissionsSources (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.
Tier 1 Foundation ElementsClassification of Refinery Wastes
WastewaterTypes 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.
Tier 1 Foundation ElementsClassification of Refinery Wastes
ResidualsTypes 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).
Tier 1 Foundation ElementsClassification of Refinery Wastes
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
QUANTIFICATION
OF WASTE DISCHARGES
Tier 1 Foundation Elements
Air Emissions
Solid Wastes
Liquid Effluents
Tier 1 Foundation ElementsQuantification of Waste Discharges
Air Emissions
Tier 1 Foundation Elements
Table 1. Average rate of air pollutants in crudeSource: 3. Pollution Prevention and Abatement Handbook
Pollutant
Average rate of
crude (mg/cm3
normal)Particulate matter (PM) 50
Sulfur oxides150 for sulfur recovery units;
500 for other units
Nitrogen oxides 460Nickel and vanadium (combined) 2Hydrogen sulfide 152
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.
Tier 1 Foundation ElementsQuantification of Waste Discharges
Liquid Effluent Approximately 3.5-5 cubic meters of wastewater per ton of crude are generated
when cooling water is recycled.
Tier 1 Foundation Elements
Table 2. Average rate of liquid pollutants in crudeSource: 3. Pollution Prevention and Abatement Handbook
PollutantAverage rate of wastewater (mg/l)
maximum valuepH 6.0-9.0BOD 30COD 150TSS 30Oil and grease 10Chromium Hexavalent 0.1 Total 0.5Lead 0.1Phenol 0.5Benzene 0.05Benzo(a)pyrene 0.05Sulfide 1
Nitrogen (total)a 10
Temperature increase ≤3oCb
a. The maximum effluent concentration of nitrogen (total) may be up to 40 mg/l in processes that include hydrogenation
b. 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.
Quantification of Waste Discharges
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
BEST AVAILABLE
TECHNOLOGIES FOR REFINERIES
Tier 1 Foundation Elements
Tier 1 Foundation ElementsBest 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.
Tier 1 Foundation Elements
NOx Flue Gas Recirculation Low NOx Burners Ultra-Low NOx Burners Selective Catalytic Reduction Selective Non-Catalytic Reduction Combination System
Best Available Technologies for Refineries
Tier 1 Foundation Elements
NOxExample-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.
Tier 1 Foundation ElementsBest Available Technologies for Refineries
NOxExample-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.
Tier 1 Foundation ElementsBest Available Technologies for Refineries
Tier 1 Foundation Elements
NOx Example-Low NOx Burner
Figure 2. Low NOx Burner EquipmentSource: http://www.netl.doe.gov/cctc/resources/database/photos/photostr3.html
Best Available Technologies for Refineries
Tier 1 Foundation Elements
NOx Example-Low NOx Burner
Figure 3. Low NOx Burner EquipmentSource: http://www.netl.doe.gov/cctc/resources/database/photos/photostr3.html
Best Available Technologies for Refineries
Tier 1 Foundation Elements
SOx
Advanced Flue Gas Desulfurization Dry Flue Gas Desulfurization (Spray Dryer Absorption)
Best Available Technologies for Refineries
Tier 1 Foundation Elements
SOxExample-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
Tier 1 Foundation Elements
SOxEjemplo-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 H2OAfter 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
Tier 1 Foundation Elements
SOxExample-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
Tier 1 Foundation Elements
Figure 4. Advanced Flue Gas DesulfurizationSource: 11.
Best Available Technologies for Refineries
Tier 1 Foundation Elements
VOCs Adsorption Systems Condensation Systems Thermal Oxidation Systems Flares Steam Stripping Tank Seals
Best Available Technologies for Refineries
Tier 1 Foundation Elements
VOCsExample-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
Tier 1 Foundation Elements
Figure 5. Steam StrippingSource: 9.
http://www.jaeger.com/Brochure/steam%20stripping.pdf#search='steam%20stripping%20equipment‘
Best Available Technologies for Refineries
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
REGULATORY
ISSUES FOR REFINERIES IN
NORTH AMERICA
Tier 1 Foundation Elements
CANADA CAC Emissions SIC and NAICS Codes Air Emissions Statistics
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
CANADACAC 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).
http://www.ec.gc.ca/pdb/ape/cape_home_e.cfm
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
CANADASIC 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.
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
CANADASIC 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 http://www.census.gov/epcd/www/naicstab.htm http://www.naics.com/info.htm
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
USAEnvironmental 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
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
USAEnvironmental 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
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
USAEnvironmental 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
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
USAEnvironmental 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 (§§311-312)
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
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
USAEnvironmental 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
Tier 1 Foundation Elements 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-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 If the complete document is needed it can be obtained at the following site:
http://cronos.cta.com.mx/cgi-bin/normas.sh/cgis/index.p
Tier 1 Foundation Elements Regulatory Issues For Refineries in North America
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
DRIVING FORCES,
HURDLES, AND POTENTIAL FOR
ENVIRONMENTAL ISSUES
Tier 1 Foundation Elements
The petroleum refining industry is a strong contributor to the economic health of the United States and Mexico.
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.
Oil well near Sarnia, Ontario
Driving Forces Hurdles and Potential for Environmental Issues
Tier 1 Foundation Elements
Tier 2
Case Study Elements
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
Tier 2 Case Study
Figure 6. Schematic of Mexican Petroleum Refining ProcessSource: E Aguuilar R. Revista del IMIQ. Año XLIII, Vol. 1-2, Enero Febrero 2002
Typical Refinery
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
Tier 2 Case StudyPreliminary Material and Energy Balances for a typical refinery
Gasoline (103,000)
LPG (11,161)
NC4 (5,844)Crude Oil (223,992)
Benzene (3,165)
223,992 BPCD
RefineryDiesel (41,200)
Overall Material Balance
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
Refinery C5-(899)
Kerosine/Jet (21,200)
Naphtha (11,276)
Xylenes (11,267)
Residual Fuel Oil (13,500)
Coke (3,278)
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
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
Tier 2 Case StudyPriority Pollutants
Pemex Refinancíon (PR)Pemex Refinancíon (PR)
Emissions and Discharges (tons)
YearEmissions to
AirDischarges to
Water
Hazardous Waste
GenerationHazardous
Spills and Leaks2001* 460,413 2,658 40,277 5,9002002** 428,531 1,663 115,693 17,623
Total Emissions and Discharges per Unit of Throughput (ton)
Totals Emissions
and Discharges Production (%)
509,249 64,627,529 0.788%563,511 64,549,127 0.873%
2002 Emissions and discharges totaled 1,148,569 tons for all sectors of PEMEX of w hich Pemex Refining contributed 49%.
Air emissions are the major contributors to environmental
pollution contributing 90.4% in 2001 and 76.0% in 2002.
Table 3. Pemex Refinery Emissions and Discharges
Tier 2 Case StudyPriority Pollutants
Emissions to Air (tons)
Year PR SOX NOX TSP TOC VOC
Total Emissions to
Air1
2001* Refineries 375,553 23,967 19,893 27,733 25,832 447,146Commercial 3 12 1 1,990 1,975 2,007Distribution 926 1,214 43 9,077 8,957 11,260
Totals 376,483 25,193 19,937 38,800 36,764 460,4132002** Refineries 332,498 24,554 20,439 27,286 25,334 404,777
Commercial 5 14 1 903 887 923Distribution 5,590 8,077 166 8,998 8,692 22,831
Totals 338,093 32,645 20,606 37,187 34,913 428,531
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).
Pemex Refinancíon (PR)Pemex Refinancíon (PR)
Table 4. Pemex Refinery Air Emissions
Tier 2 Case StudyPriority Pollutants
Discharges to Water (tons)
Year PR O&G TSS Ntot OthersTotal Disharges
to Water
2001* Refineries 634 1,162 686 43 2,525
Commercial 1 2 - - 3
Distribution 17 110 2 1 130
Totals 652 1,274 688 44 2,658
2002** Refineries 209 809 447 33 1,498
Commercial 1 3 - - 4
Distribution 18 139 3 1 161
Totals 228 951 450 34 1,663
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.
Pemex Refinancíon (PR)Pemex Refinancíon (PR)
Table 5. Pemex Refinery Discharges to Water
Tier 2 Case StudyPriority Pollutants
Greenhouse gases, namely CO2 emissions, are the major source of hazardous wastes.
Carbon Dioxide emissions steadily declined from 1999 to 2001 (1999 -15.09 millions of tons, 2000-14.18 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).
Pemex Refinancíon (PR)Pemex Refinancíon (PR)Hazardous Wastes (tons)
Year PR Total Generation Total Quantity
Total Spilled and Leaked
Hydrocarbons
Total Emissions and
Discharges
Greenhouse Gases-CO2
emissions (millions of tons)
2001* Refineries 38,377 1 - 488,048 13.07
Commercial 820 2 2 2,833 -
Distribution 1,080 70 5,898 18,368 0.63
Totals 40,277 73 5,900 509,249 13.70
2002** Refineries 106,927 1 108 513,310 13.24
Commercial 573 2 18 1,518 0.00
Distribution 8,193 50 17,497 48,682 1.00
Totals 115,693 53 17,623 563,511 14.24
Table 6. Pemex Refinery Hazardous Waste
Tier 2 Case StudyPriority Pollutants
Hydrocarbon Spills Hydrocarbon Leaks
Sea Land Air
Year Number Volume (barrels) Number Volume (barrels) Number Quantity (tons)
2001* 4 13 67 43,493 2 1
2002** 1 2 50 127,965 2 0
Hydrocarbon spills on land account for the majority of hydrocarbon spills and leaks.
Pemex Refinancíon (PR)Pemex Refinancíon (PR)
Table 7. Pemex Refinery Hydrocarbon Spills
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
Energy Use
Estimated Energy Use by Refining Process
Process
Specific Energy Use
(103 Btu/bbl) Average Use (103 Btu/bbl) Capacity (106 Btu/bbl)
Annual Energy Use
(1012 Btu/year)Atmospheric Distillation 82-186 113.8 15.45 641.6Vacuum Distillation 51-113 91.5 7.15 238.8Visbreaking -Coil 136 136 0.0215 1.07 -Soaker 25-95 63 0.0436 1.00Delayed Coking (net) 114-230 166 1.671 114.6Fluid Coking (net) 258 258 0.075 7.1Flexicoking (net) 167 167 0.112 6.7Fluid Catalytic Cracking 50-163 100 5.2 190.6Catalytic Hydrocracking 159-321 240 1.3 109.7Catalytic Hydrotreating 61-164 120 10.7 468.3Catalytic Reforming 213-342 284 3.6 376.3Alkylation -Sulfuric Acid 330-340 335 0.44 53.3 -Hydrofluoric Acid 401 401 0.66 95.5Ethers Production 295-564 403 0.18 33.4Isomerization -Isobutane 359 359 0.098 13.0 -Isopentane/Isohexane 102-236 175 0.42 27 -Isobutylene 476 476 n/a n/aLube Oil Manufacture 1506 1506 0.20 109.5TOTAL 2487.5
Table 8. Estimated Energy Use by Refining Process
Tier 2 Case StudyQuantification of Energy-Related Issues in Regards to Pollution
Tier 2 Case StudyQuantification of Energy-Related Issues in Regards to Pollution
Air Emissions Factors for Petroleum Refining Processes (lbs/1000 barrels of fresh feed)
Process SOX NOX COTotal Hydro-
carbonsAlde-hydes Ammonia Particulates
Fluid Catalytic Cracking Units -Uncontrolled 493 71 13,700 220 19 54 242 -Electrostatic Precipator and CO Boiler 493 71 Neg Neg Neg Neg 45Moving Bed Catalytic Crackers 60 5 3,800 87 12 6 17Fluid Cokers -Uncontrolled ND ND ND ND ND ND 523 -Electrostatic Precipator and CO Boiler ND ND Neg Neg Neg Neg 6.8Vacuum Distillation Column Condensers -Uncontrolled Neg Neg Neg 50 Neg Neg Neg -Controlled (vented to heater or incinerator) Neg Neg Neg Neg Neg NegClaus Plant and Tail Gas Treatment -SCOT Absorber and Incinerator 5.66 Neg Neg Neg Neg Neg Neg -Incinerator Exhaust Stack (2 catalytic stages) 85.9 Neg Neg Neg Neg Neg NegBlowdown Systems -Uncontrolled Neg Neg Neg 580 Neg Neg Neg -Vapor Recovery System and Flaring 26.9 18.9 Neg 0.8 Neg Neg Neg
Table 9. Air Emission Factors by Process
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
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.
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
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?”
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Problem Statement
StreamG i
kg/syi
s yit
R1 8.00 0.1 0.01R2 6.00 0.08 0.01
Rich stream
StreamLc
j
kg/sxj
s xjt mj bj
cj
$/kgS1 10.00 0.01 0.02 2.00 0.00 0.00S2 0.00 0.11 0.02 0.00 0.08
MSAs
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Data
Tables 10 & 11. Data for Phenolic Wastewater Problem
Sweet Gasoline
Middle Distillates
Gas
Gasoline
Light Gas Oil
Wastewater, R1
Lube Oil
Waxes
Gasoline, Naphtha and Middle distillates
Fuel Oil
Asphalt
Wastewater, R2
LPH and Gas
Gasoline
Naphta
Middle Distillates
Gas Oil
Lube-BaseStocks
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
The Process
Stabilizer
Atm
osp
heri
cD
ist i
llati
on
VacuumDistillation
SweeteningUnit
Visbreaker
Hydrotreating
CatalyticCracking
Solvent Extraction and
Dewaxing
Tre
ati
ng
an
d B
len
din
g
Refinery fuel gas
Refinery fuel oil
Industrial fuels
Asphalts
Greases
Lube oils
Aviation fuels
Diesels
Heating oils
LPG
Gasoline
Solvents
Figure 8. Petroluem Refining Process
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
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.
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.
Process Description
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Rich Stream Plot
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
R1
R2
y1t, y2
t y2
s y1s
Mas
s ex
chan
ged
Figure 10. Plot of Rich Stream
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Rich Stream Plot
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
R1
R2
y1t, y2
t y1 y2s
Ma
ss e
xch
an
ge
d
Figure 11. Plot of Rich Stream
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
One-To-One Correspondence
To generate the one-to-one correspondence, we use the following equation:y=f(x j+εj)
Where εj is the minimum allowable composition difference. ε j=0.01
In this case the equilibrium equation is linear: y = m(x+ε) + b
y1s = 2(0.01+0.01) = 0.04 y2
s = 0.02(0.00+0.01) = 0.0002
y1t = 2(0.02+0.01) = 0.06 y2
t = 0.02(0.11+0.01) = 0.0024
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Lean Stream Plot
Figure 12. Plot of Lean Stream
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
MS1
y
x1
x2S2
S1
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Obtain A Pinch-Point
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
Mass
exc
hanged
Figure 13. Plot of Lean Stream with Pinch Point Indicated
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
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).
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Interpret Results
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
Mas
s ex
chan
ged
0.1
Figure 14. Shifting the Lean Stream
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
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).
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Interpret Results
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
Figure 15. Shifting the Lean Stream
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
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).
Preliminary Targets for Environmental Discharges Using Process Integration
Tier 2 Case Study
Interpret Results
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
Mas
s ex
chan
ged
Mass removed by Process MSA
Mass removed by External MSA
y
Figure 16. Mass Removed by Process MSA and External MSA
Tier 3
Open-Ended Problem
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.
Tier 3 Open-Ended Problem
Utilizing Case Study
Diesel (22.0%)
Heavy Fuel Oil (33.3%)
Gasoline (33.0%)
Oil
Kerosine (6.6%)
250,000 BPD Refinery
LPG (5.1%)
Tier 3 Open-Ended Problem
Utilizing Case Study
Note: Keep in mind that in a detailed overall refinery balance, there are other outputs besides the desired products.
Figure 17. Overall mass balance for a typical Mexican refinery.
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.
Tier 3 Open-Ended Problem
Utilizing Case Study
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
This is the end of Module #2.
Please submit your report to your professor for grading.
Resources
1. Rossiter, Alan P. Waste Minimization through Process Design. MacGraw Hill. 1995.
2. Cheremisinoff, Nicholas P. Handbook of Pollution Prevention Practices. Marcell Dekker Inc. 2001.
3. The World Bank Group. Pollution Prevention and Abatement Handbook 1998.
4. http://www.ec.gc.ca/pdb/ape/cape_home_e.cfm5. El-Halwagi, M.M. Pollution Prevention Through Process Integration.
Academic Press. 1997.6. Environmental Update #12, Hazardous Substance Research
Centers/Southwest Outreach Program, June 2003. www.hsrc.org/hsrc/html7ssw/update12.pdf
7. Energy and Environmental Profile of the U.S. Petroleum Industry. December 1998. U.S. Department of Energy, Office of Industrial Technologies.
8. EPA Office of Compliance Sector Notebook Project, Profile of the Petroleum Refining Industry, September 1995.
Resources
9. http://www.jaeger.com/brochure/steam%20stripping.pdf10. 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.
11. http://www.naics.com/info.htm12. http://www.netl.doe.gov/cctc/resources/database/photos/
photostr3.html13. Revista Del IMIQ. Enero Febrero 2002. Instituto Mexicano de
Ingenieros Químicas A.C. ISSN 0188-7319/Año XLIII, Vol 1-2.14. *PEMEX Sustainable Development: Safety, Health and Environment,
Report 2001.15. **PEMEX Sustainable Development: Safety, Health and Environment,
Report 2002. http://www.pemex.com/files/seguridad/Proteccionambientali.pdf