Sub-sectoral Environmental Guidelines PETROLEUM REFINERIES

Transcription

1 Sub-sectoral Environmental Guidelines PETROLEUM REFINERIES PROCESS DESCRIPTION This guidance note covers the refining of crude petroleum to produce gases, liquids, greases and tars which are either used as products in their own right or as the precursors of petrochemicals for further industrial processes. Typical refinery products include: natural gas and liquefied petroleum gas (LPG); solvent naphthas; jet fuel; kerosene; diesel oils; lubricating oils; various fuel oils; waxes; bitumen. Not all of these will necessarily be produced by a single refinery. Some refineries are dedicated to particular products, e.g. lube oil refinery. Petroleum refining involves two basic processes: separation and conversion. Crude petroleum enters the refinery and is separated into various fractions by distillation in stills. Each still typically consists of heat exchangers, a furnace, a fractionating tower, steam strippers, condensers, coolers and auxiliaries. Separation processes also include absorption, adsorption, filtration, crystallisation and extraction. Conversion processes include a number of chemical reactions. The most important of these are: Polymerization - the conversion of gases produced in cracking, into liquid fuels; Alkylation - the production of isoparaffins (used in gasoline) using hydrogen fluoride and sulphuric acid as catalysts; Isomerization - changing the arrangement of the atoms in a molecule, e.g. butane to isobutane; Reforming - a high temperature catalytic treatment converting the constituents into similar sized modules but with higher octane ("anti-knock") ratings. In addition to separation and cracking, together with blending and mixing processes, various other chemical treatments take place involving: removal of various constituents, primarily sulphur, but also resins and asphaltic materials; improvement of colour; 1

2 improvement of odour; improvement of stability; addition of various constituents such as antioxidants to prevent gum formation. Waste treatment processes also account for a significant area of the refinery, particularly sulphur compounds in gaseous emissions together with various solid and liquid extracts and wastes generated during the refining process. The refinery is therefore composed of a complex system of stills, crackers, processing and blending units and vessels in which the various reactions take place, as well as packaging units for products for immediate distribution to the retailer, e.g. lubricating oils. Bulk storage tanks usually grouped together in bunded tank farms are used for storage of both crude and refined products. Other tanks are used in the processes outlined, e.g. treating, blending and mixing whilst others are used for spill and fire control systems. A boiler and electrical generating system usually operate for the refinery as a whole. SUMMARY OF KEY ENVIRONMENTAL RISK/LIABILITY FACTORS Atmospheric Emissions Principal sources of releases to air from refineries include: combustion plants, emitting sulphur dioxide, oxides of nitrogen and particulates; refining operations, emitting sulphur dioxide, oxides of nitrogen, carbon monoxide, particulates, volatile organic compounds, hydrogen sulphide, mercaptans and other sulphurous compounds; bulk storage operations and handling of volatile organic compounds (various hydrocarbons). Regulatory requirements - air emission permits stipulating limits for specific pollutants, and possibly health and hygiene permit requirements. Requirement for monitoring programme. Fees and penalties. Requirements to upgrade pollution abatement equipment. Storage and Handling of Petroleum Products Large quantities of environmentally-sensitive petroleum products are stored in: tank farms (multiple tanks); single above-ground storage tanks (ASTs); semi-underground, or underground storage tanks (USTs). Smaller quantities of materials may be stored in: 2

3 drums and containers of assorted compounds (such as lubricating oil, engine oil, other products for domestic supply). Secondary containment of tanks and other storage areas (with adequate bunding etc.) and integrity of hardstanding (without cracks, impervious surface) to prevent spills reaching the wider environment: also secondary containment of pipelines where appropriate. Licensing of storage facilities. Age, construction details and testing programme of tanks. Labelling and environmentally secure storage of drums (including waste storage). Accident/fire precautions, emergency procedures. Disposal/recycling of waste or "out of spec" oils and other materials. Soil and Groundwater Contamination There is a potential for significant soil and groundwater contamination to have arisen at petroleum refineries. Such contamination consists of: Petroleum hydrocarbons including: lighter, very mobile fractions (paraffins, cycloparaffins and volatile aromatics such as benzene, toluene, ethylbenzene and xylenes) typically associated with gasoline and lighter distillates; middle distillate fractions (paraffins, cycloparaffins and some polyaromatics) associated with diesel, kerosene, some of the lighter fuel oils, which are also of significant mobility; heavier distillates (long-chain paraffins, cycloparaffins and polyaromatics) associated with lubricating oils and heavy fuel oils; Various organic compounds associated with petroleum hydrocarbons or produced during the refining process, e.g. phenols, amines, amides, alcohols, organic acids, nitrogen and sulphur containing compounds. Other organic additives, e.g. anti-freeze (glycols), alcohols, detergents and various proprietary compounds. Organic lead, associated with leaded gasoline and other heavy metals. Key sources of such contamination at petroleum refineries are: transfer and distribution points in tankage and process areas, also general loading and unloading areas; landfarm areas; tank farms, individual ASTs and particularly USTs; interceptors; additive compounds; pipeline runs; drainage runs; pump raft/pipe manifold areas; 3

4 vehicle washing facilities; maintenance workshops; on-site waste treatment facilities, impounding basins, lagoons, especially if unlined. Whilst contamination may be associated with specific facilities the contaminants are relatively highly mobile in nature and have the potential to migrate significant distances from the source in soil and groundwater. Petroleum hydrocarbon contamination can take several forms: free-phase product, dissolved-phase, emulsified phase or vapour phase. Each form will require different methods of remediation so that clean-up may be complex and expensive. Petroleum hydrocarbons include a number of compounds of significant toxicity, e.g. benzene and some polyaromatics are known carcinogens. Vapour phase contamination can be of significance in terms of odour issues etc. Fire Risks Due to the obvious risk of fire, refineries are equipped with sprinkler or spray systems which may draw upon the mains supply of water, or water held in lagoons, or from reservoirs or neighbouring water courses. Fire water so produced will be polluting and require containment. Asbestos Asbestos may be a significant issue at petroleum refinery sites particularly as insulating material/lagging associated with furnaces, combustion areas etc., and in a range of structures including building materials. Removal from the site can be costly. FINANCIAL IMPLICATIONS Risk of major spills resulting in substantial liability claims or regulatory enforcement action. Contamination of soil, groundwater and surface water bodies due to historical and/or present use of petroleum products. Soil and groundwater contamination relating to petroleum products is extremely costly to remediate and could be severely disruptive to site operations. Fees and penalties (particularly relating to air emissions and effluent discharges). Run-off/stormwater drainage from storage areas on refinery. Outstanding claims (health and safety). 4

5 Upgrade of storage areas may be required. Upgrade of pollution abatement equipment particularly relating to air emissions and site infrastructure (sewers, drainage, interceptors) may be required. Major fires and spills could be financially ruinous. OTHER POTENTIAL ENVIRONMENTAL ISSUES Water Supply/Wastewater Management Facilities will require significant volumes of water for on-site processes (e.g. coolants, blow-downs etc.) as well as for sanitary and potable use;. Wastewater will derive from these sources (process water) and from stormwater run-off. The latter could contain significant concentrations of petroleum product. Petroleum hydrocarbons, either dissolved, emulsified or occurring as freephase will be the key constituents although wastewater may also contain significant concentrations of phenols, amines, amides, alcohols, ammonia, sulphide, heavy metals and suspended solids. Wastewaters may be collected in separate drainage systems (for process, sanitary and stormwater) although industrial and stormwater systems may in some cases be combined. In addition, ballast water from bulk crude tankers may be pumped to receiving facilities at the refinery site prior to removal of floating oil in an interceptor and treatment as for other wastewater streams. On-site treatment facilities may exist for wastewater or treatment may take place at a public wastewater treatment plant. Stormwater/process water is generally passed to a separator or interceptor prior to leaving the site which takes out free-phase oil (i.e. floating product) from the water prior to discharge, or prior to further treatment, e.g. in settling lagoons). Discharge from wastewater treatment plants is usually passed to a nearby water course. Source of process, potable and sanitary water (municipal, on-site, abstraction, surface water etc.). Permits and charges for water use. Ability of industrial sewer system to capture all process effluents and also stormwater run-off. Separation of sanitary from industrial/stormwater systems where required, and separation of water from any on-site vehicle washing facilities from interceptors. Integrity of drainage system critical requirements for regular inspection and monitoring of drainage system, also lining of drainage ditches, impounding basins and lagoons. 5

6 Possibility of accidental releases of petroleum products reaching local water courses or entering sanitary sewage system. Efficiency of wastewater treatment system and interceptors/separators critical, check type, effectiveness, monitoring, final effluent and sludge disposal. Regulatory compliance discharge consents, enforcement, requirements for ongoing effluent monitoring costs. Requirements and costs for potential upgrade of wastewater treatment plant and interceptors/separators. Waste Management Typical wastes include: waste oils, process chemicals, still resides; "out of spec." materials; waste alkali (sodium hydroxide); waste oil sludge (from interceptors, tanks, lagoons etc.); solid wastes (cartons, rags, etc.). Regulatory requirements. Means of solid waste disposal management. Storage of waste on-site prior to disposal. Disposal permits. Fees and penalties. Use of approved disposal routes (and contractors). Ownership of waste disposal site. Potential pollution of soil and groundwater related to on-site and off-site storage and disposal. Polychlorinated Biphenyls (PCBs) Where transformers and capacitors are present, it is possible that these may contain PCBs, requiring removal from site, or at the very least provided with adequate containment and proper fire hazard prevention measures. Noise It is possible that noise may reach or exceed nuisance levels, particularly on sites close to the residential areas. Odour Odour may be a nuisance in sensitive areas and provision of odour control devices may be necessary. 6

7 ENVIRONMENTAL IMPROVEMENTS Upgrade material storage areas, especially underground storage facilities. Minimise underground storage or underground pipelines in favour of aboveground structures. Provide secondary containment facilities for all pipelines, tanks and drum storage areas; Upgrade air emissions control, particularly fugitive emissions; Installation of loss detectors on long pipe runs; Improve heat transfer and pipe insulation; Introduction of good environmental engineering practice; Improvements of wastewater treatment facilities and interceptors to achieve lower discharge; Improvements of integrity of all waste or wastewater containment facilities (ditches, lagoons etc.); Separation of wastewater streams where appropriate. ENVIRONMENTAL ACTION PLAN Develop an Environmental Action Plan (EAP) to include: regulatory compliance measures; waste management plan (waste minimisation, re-use, recycling, monitoring); health and safety improvements; costs of upgrades/compliance; assessment and remediation of contaminated soil and groundwater; roles and responsibilities, time-frame and benchmarks. GUIDE TO INITIAL DUE DILIGENCE SITE VISITS When visiting the sites of potential borrowers or during loan supervision, use the following as practical guide to the initial due diligence process. Perform a complete tour of the site compound if possible. Note quantities and characteristics of atmospheric emissions, wastewater discharges and solid and hazardous waste arising. Note signs of poor housekeeping, inadequate/untidy storage areas, poor drum labelling. Review current status of pollution abatement technology. Evaluate potential for spillages and leakages to enter soil or stormwater drainage system. Check drainage systems. Note nature of solid waste disposal. Look for localised spills, leaking tanks, pipes etc.. Check for distressed flora/vegetation zones near storage sites. Check personal protective equipment. Review machinery guarding. 7

8 Assess emergency response to fires, major spills, etc.. Review historical and projected trends for environmental fees and fines. It is also suggested that contact is made with local regulatory agencies to determine compliance and whether complaints have been made by the public. 8