E NVIRONMENTAL C HALLENGES O VERVIEW F ACING THE P ETROLEUM I NDUSTRY:

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

3. 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.

4. STRUCTUREOF 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:

5. Tier 1 Foundation Elements

6. 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

7. 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

8. Tier 1 Foundation Elements ROLE OF PROCESS INTEGRATION IN FACING THE CHALLENGE, AVAILABLE TOOLS, TOOLS TO BE DEVELOPED

9. Tier 1 Foundation Elements • 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.

10. 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

11. 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.

12. Tier 1 Foundation Elements • BASIC PROCESSES OF A REFINERY

13. Tier 1 Foundation Elements • 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.

14. 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

15. Tier 1 Foundation Elements • 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.

16. Tier 1 Foundation Elements • 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

17. Tier 1 Foundation Elements • 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)

18. Tier 1 Foundation Elements • 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.

19. Tier 1 Foundation Elements • Basic Processes of a Refinery 2.2 Conversion Processes • Thermal Processes • Catalytic Processes • Property Improvement Processes

20. Tier 1 Foundation Elements • Basic Processes of a Refinery 2.2 Conversion Processes Examples: • Cracking (thermal and catalytic) • Catalytic Reforming • Alkylation • Polymerization • Isomerization • Coking • Visbreaking

21. Tier 1 Foundation Elements • 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

22. Tier 1 Foundation Elements • Basic Processes of a Refinery 2.3 Treating Processes Examples • Hydrotreatment/hydrogenation • Chemical Sweetening • Hydrodesulfurization • Acid gas removal • Gas Treatment

23. Tier 1 Foundation Elements • 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.

24. Tier 1 Foundation Elements • Basic Processes of a Refinery 2.4 Blending Processes • Storage • Blending • Loading • Unloading

25. Tier 1 Foundation Elements • 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.

26. Tier 1 Foundation Elements • Basic Processes of a Refinery 2.5 Auxiliary Processes • Boilers • Waste water treatment • Stack gas processing • Hydrogen production • Sulfur recovery plant

27. 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

28. Tier 1 Foundation Elements • CLASSIFICATION OF REFINERY WASTES View of the Shell/Valero Martinez oil refinery Image taken July 20, 2004 by User:Leonard G.

29. Tier 1 Foundation Elements • Classification of Refinery Wastes • Air Emissions • Wastewater • Residuals • Total Environmental Discharges by Process

30. Tier 1 Foundation Elements • 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.

31. Tier 1 Foundation Elements • 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.

32. Tier 1 Foundation Elements • 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.

33. Tier 1 Foundation Elements • 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).

34. 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

35. Tier 1 Foundation Elements • QUANTIFICATION OF WASTE DISCHARGES

36. Tier 1 Foundation Elements • Quantification of Waste Discharges • Air Emissions • Solid Wastes • Liquid Effluents

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

38. Tier 1 Foundation Elements • 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.

39. Tier 1 Foundation Elements • Quantification of Waste Discharges Liquid Effluent • Approximately 3.5-5 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

40. 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

41. Tier 1 Foundation Elements BEST AVAILABLE TECHNOLOGIES FOR REFINERIES

42. Tier 1 Foundation Elements • 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.

43. Tier 1 Foundation Elements • 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

44. 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.

45. Tier 1 Foundation Elements • 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.

46. Tier 1 Foundation Elements • Best Available Technologies for Refineries NOx Example-Low NOx Burner Figure 2. Low NOx Burner Equipment Source: http://www.netl.doe.gov/cctc/resources/database/photos/photostr3.html

47. Tier 1 Foundation Elements • Best Available Technologies for Refineries NOx Example-Low NOx Burner Figure 3. Low NOx Burner Equipment Source: http://www.netl.doe.gov/cctc/resources/database/photos/photostr3.html

48. Tier 1 Foundation Elements • Best Available Technologies for Refineries SOx Advanced Flue Gas Desulfurization Dry Flue Gas Desulfurization (Spray Dryer Absorption)

49. Tier 1 Foundation Elements • 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.

50. Tier 1 Foundation Elements • 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.