Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Environmental, Health and Safety Guidelines for Large Volume Petroleum-based Organic Chemicals Manufacturing Introduction environmental assessment in which site-specific variables, such as host country context, assimilative capacity of the The Environmental, Health, and Safety (EHS) Guidelines are environment, and other project factors, are taken into account. technical reference documents with general and industry- The applicability of specific technical recommendations should specific examples of Good International Industry Practice be based on the professional opinion of qualified and (GIIP) 1. When one or more members of the World Bank Group experienced persons. are involved in a project, these EHS Guidelines are applied as required by their respective policies and standards. These When host country regulations differ from the levels and industry sector EHS guidelines are designed to be used measures presented in the EHS Guidelines, projects are together with the General EHS Guidelines document, which expected to achieve whichever is more stringent. If less provides guidance to users on common EHS issues potentially stringent levels or measures than those provided in these EHS applicable to all industry sectors. For complex projects, use of Guidelines are appropriate, in view of specific project multiple industry-sector guidelines may be necessary. A circumstances, a full and detailed justification for any proposed complete list of industry-sector guidelines can be found at: alternatives is needed as part of the site-specific environmental www.ifc.org/ifcext/enviro.nsf/Content/EnvironmentalGuidelines assessment. This justification should demonstrate that the choice for any alternate performance levels is protective of The EHS Guidelines contain the performance levels and human health and the environment measures that are generally considered to be achievable in new facilities by existing technology at reasonable costs. Application Applicability of the EHS Guidelines to existing facilities may involve the The EHS Guidelines for Large Volume Petroleum-based establishment of site-specific targets, with an appropriate Organic Chemical Manufacturing include information relevant to timetable for achieving them. The applicability of the EHS large volume petroleum-based organic chemicals (LVOC) Guidelines should be tailored to the hazards and risks projects and facilities. They cover the production of following established for each project on the basis of the results of an products: 1 Defined as the exercise of professional skill, diligence, prudence and foresight that would be reasonably expected from skilled and experienced professionals engaged in the same type of undertaking under the same or similar • Lower Olefins from virgin naphtha, natural gas, and gas circumstances globally. The circumstances that skilled and experienced oil with special reference to ethylene and propylene and professionals may find when evaluating the range of pollution prevention and control techniques available to a project may include, but are not limited to, general information about main co-products [C4, C5 varying levels of environmental degradation and environmental assimilative capacity as well as varying levels of financial and technical feasibility. MARCH 2APRIL 30, 2007 1 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP streams, pyrolytic gasoline (py-gas)], as valuable feedstock 1.0 Industry-Specific Impacts for organic chemicals manufacturing. and Management • Aromatics with special reference to the following The following section provides a summary of the most compounds: benzene, toluene, and xylenes by extraction significant EHS issues associated with LVOC manufacturing or extractive distillation from pyrolytic gasoline (py-gas); facilities, which occur during the operational phase, along with ethylbenzene and styrene by dehydrogenation, or oxidation recommendations for their management. Recommendations for with propylene oxide co-production; and cumene and its the management of EHS impacts common to most large oxidation to phenol and acetone. industrial facilities during the construction and decommissioning • Oxygenated Compounds with special reference to the phases are provided in the General EHS Guidelines. following compounds: formaldehyde by methanol oxidation; MTBE (methyl t-butyl ether) from methanol and isobutene; 1.1 Environmental ethylene oxide by ethylene oxidation; ethylene glycol by Potential environmental issues associated with LVOC ethylene oxide hydration; and terephthalic acid by oxidation manufacturing include the following: of p-xylene; acrylic esters by propylene oxidation to acrolein and acrylic acid plus acrylic acid esterification. • Air emissions • Nitrogenated Compounds with special reference to the • Wastewater following compounds: acrylonitrile by propylene • Hazardous materials ammoxidation, with co-production of hydrogen cyanide; • Wastes caprolactam from cyclohexanone; nitrobenzene by • Noise benzene direct nitration; and toluene diisocyanate (TDI) from toluene. Air Emissions • Halogenated Compounds with special reference to the Emission sources from chemical processes include process tail following compounds: ethylene dichloride (EDC) by gases, heaters and boilers; valves, flanges, pumps, and ethylene chlorination and production of vinyl chloride compressors; storage and transfer of products and (VCM) by dehydrochlorination of EDC as well by ethylene intermediates; waste water handling; and emergency vents and oxychlorination. flares. This document is organized according to the following sections: Industry-specific pollutants that may be emitted from point or fugitive sources during routine operations consist of numerous Section 1.0 — Industry-Specific Impacts and Management Section 2.0 — Performance Indicators and Monitoring organic and inorganic compounds, including sulfur oxides (SOX), Section 3.0 — References ammonia (NH3), ethylene, propylene, aromatics, alcohols, Annex A — General Description of Industry Activities oxides, acids, chlorine, EDC, VCM, dioxins and furans, formaldehyde, acrylonitrile, hydrogen cyanide, caprolactam, and other volatile organic compounds (VOCs) and semivolatile organic compounds (SVOC). APRIL 30, 2007 2 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Air quality impacts should be estimated by the use of baseline operation, VOC emissions from the cracking process are air quality assessments and atmospheric dispersion models to usually reduced because they are recycled, used as fuel or establish potential ground-level ambient air concentrations routed to associated processes in an integrated site. during facility design and operations planning as described in Elevated VOC emissions from ethylene plants are the General EHS Guidelines . These studies should ensure that intermittent, and may occur during plant start-up and no adverse impacts to human health and the environment result. shutdown, process upsets, and emergencies. Combustion sources for power generation are common in this Recommended emission prevention and control measures industry sector. Guidance for the management of small include the following: combustion source emissions with a capacity of up to 50 megawatt hours thermal (MWth), including air emission • Implementing advanced multi-variable control and on-line standards for exhaust emissions, is provided in the General optimization, incorporating on-line analyzers, performance EHS Guidelines . Guidance applicable to emissions sources controls, and constraint controls; greater than 50 MWth are presented in the EHS Guidelines for • Recycling and/or re-using hydrocarbon waste streams for Thermal Power. heat and steam generation; • Minimizing the coke formation through process Process Emissions from Lower Olefins Production optimization; Typically, the olefins plants are part of an integrated • Use of cyclones or wet scrubbing systems to abate petrochemical and/or refining complex and are frequently used particulate emissions; to recover vent and purge streams from other units (e.g., • Implementing process control, visual inspection of the polymer manufacturing plants). Process emissions are mainly emission point, and close supervision of the process the following: parameters (e.g., temperatures) during the de-coking phase; • Periodic decoking of cracking furnaces to remove carbon • Recycling the decoking effluent stream to the furnace build-up on the radiant coils. Decoking produces firebox where sufficient residence time permits total significant particulate emissions and carbon monoxide; combustion of any coke particles; • Flare gas systems to allow safe disposal of any • Flaring during startup should be avoided as much as hydrocarbons or hydrogen that cannot be recovered in the possible (flareless startup); process (i.e., during unplanned shutdowns and during • Minimizing flaring during operation2; start-ups). Crackers typically have at least one elevated • Collecting emissions from process vents and other point flare as well as some ground flares; and sources in a closed system and routing to a suitable purge • VOC emissions from pressure relief devices, venting of off- gas system for recovery into fuel gas or to flare; specification materials or depressurizing and purging of • Adopting closed loop systems for sampling; equipment for maintenance. Crack gas compressor and refrigeration compressor outages are potential sources of 2 The normally accepted material loss for good operating performance is around short-term, high rate VOC emissions. During normal 0.3 - 0.5 % of hydrocarbon feed to the plant (5 to 15 kg hydrocarbons/tonne ethylene). APRIL 30, 2007 3 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP • Hydrogen sulfide generated in sour gas treatment should • VOC emissions from storage tank breathing losses and be burnt to sulfur dioxide or converted to sulfur by Claus displacement of tanks for raw materials, intermediates, and unit; final products. • Installing permanent gas monitors, video surveillance and Recommended emission prevention and control measures equipment monitoring (such as on-line vibration monitoring) include the following: to provide early detection and warning of abnormal conditions; and • Routine process vents and safety valve discharges should • Implementing regular inspection and instrument monitoring preferably be conveyed to gas recovery systems to to detect leaks and fugitive emissions to atmosphere (Leak minimize flaring; Detection and Repair (LDAR) programs). • Off-gas from hydrogenations should be discharged to a fuel gas network and burnt in a furnace to recover calorific Process Emissions from Aromatics Production value; Emissions from aromatics plants are to a large extent due to the • Dealkylation off-gases should be separated in a hydrogen use of utilities (e.g., heat, power, steam, and cooling water) purification unit to produce hydrogen (for recycle) and needed by the aromatics separation processes. Emissions methane (for use as a fuel gas); related to the core process and to the elimination of impurities • Adopting closed loop sample systems to minimize operator include: exposure and to minimize emissions during the purging • Vents from hydrogenations (pygas hydrostabilization, step prior to taking a sample; cyclohexane reaction) may contain hydrogen sulfide (from • Adopting ‘heat-off’ control systems to stop the heat input the feedstock desulphurization), methane, and hydrogen; and shut down plants quickly and safely in order to • Dealkylation off-gases; minimize venting during plant upsets; • VOC (e.g., aromatics (benzene, toluene), saturated • Where the process stream contains more than 1 weight aliphatics (C1–C4) or other aliphatics (C2–C10)) emissions percent (wt% ) benzene or more than 25 wt% aromatics, from vacuum systems, from fugitive sources (e.g., valve, use closed piping systems for draining and venting flange and pump seal leaks), and from non-routine hydrocarbon containing equipment prior to maintenance; operations (maintenance, inspection). Due to lower and use canned pumps or, where they are not applicable, operating temperatures and pressures, the fugitive single seals with gas purge or double mechanical seals or emissions from aromatics processes are often less than in magnetically driven pumps; other LVOC manufacturing processes where higher • Minimizing fugitive leaks from rising stem manual or control temperatures and pressures are needed; valve fittings with bellows and stuffing box, or using high- • VOC emissions from leaks in the cooling unit when integrity packing materials (e.g., carbon fiber); ethylene, propylene, and/or propane are used as coolant • Using compressors with double mechanical seals, or a fluids in the p-xylene crystallization unit; process-compatible sealing liquid, or a gas seal; APRIL 30, 2007 4 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP • Using double seal floating roof tanks or fixed roof tanks • Abatement of the absorber off-gases in the silver process incorporating an internal floating rood with high integrity with gas engines and dedicated thermal oxidation with seals; and steam generation; • Loading or discharging of aromatics (or aromatics-rich • Treatment of reaction off-gas from the oxide process with a streams) from road tankers, rail tankers, ships and barges dedicated catalytic oxidation system; and should be provided with a closed vent systems connected • Minimization of vent streams from storage tanks by back- to a vapor recovery unit, to a burner, or to a flare system. venting on loading/unloading and treating the polluted streams by thermal or catalytic oxidation, adsorption on Process Emissions from Oxygenated Compounds activated carbon (only for methanol storage vents), Production absorption in water recycled to the process, or connection Formaldehyde to the suction of the process air blower (only for Primary sources of formaldehyde process emissions are the formaldehyde storage vents). following: MTBE (methyl t-butyl ether) • Purged gases from the secondary absorber and the MTBE has a vapor pressure of 61 kPa at 40 ºC, and an odor product fractionator in the silver process; threshold of 0.19 mg/m3. Fugitive emissions from storage • Vented gases from the product absorber in the oxide facilities should be controlled and prevented adopting process; appropriate design measures for storage tanks . • A continuous waste gas stream for both the silver and oxide processes from the formaldehyde absorption column; Ethylene Oxide/Ethylene Glycol and The main air emissions from ethylene oxide (EO)/ethylene • Fugitive emissions and emissions arising from breathing of glycol (EG) plants are the following4: storage tanks. • Carbon dioxide, as a by-product during the manufacture of Typically, waste gases from the silver process should be treated EO, removed by absorption in a hot carbonate solution, thermally. Waste gases from the oxide process and from and then stripped and vented to air with minor quantities of materials transfer and breathing of storage tanks should be ethylene and methane; treated catalytically.3 Specific recommended emission • Purge gas from recycle gas to reduce the build-up of inert prevention and control measures include the following: gases and vented to air after treatment. In the oxygen based process, the purge gas consists mainly of • Connection of vent streams from absorber, storage and hydrocarbons (e.g., ethylene, methane, etc.) and inert loading/unloading systems to a recovery system (e.g., gases (mainly nitrogen and argon impurities present in the condensation, water scrubber) and/or to a vent gas ethylene and oxygen feedstock). After treatment, the treatment (e.g., thermal/catalytic oxidizer, central boiler plant); 3 EIPPCB BREF (2003) 4 Ibid. APRIL 30, 2007 5 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP remaining gases (mainly nitrogen and carbon dioxide) are • Adoption of high-integrity sealing systems for pumps, vented to atmosphere; compressors, and valves and use of proper types of O-ring • VOC and some compounds with lower volatility (due to and gasket materials; mechanical entrainment) from open cooling towers where • Adoption of a vapor return system for EO loading to EO-solution is stripped, cooled and re-routed to the minimize the gaseous streams requiring further treatment. absorber; Displaced vapors from the filling of tankers and storage • EO containing non-condensable gases like argon, ethane, tanks should be recycled either to the process or scrubbed ethylene, methane, carbon dioxide, oxygen, and/or prior to incineration or flaring. When the vapors are nitrogen vent gases from various sources in the process scrubbed (e.g., vapors with low content in methane and (e.g., flashing steps in the EO recovery section, EO ethylene), the liquid effluent from the scrubber should be purification section, process analyzers, safety valves, EO routed to the desorber for EO recovery; storage or buffer vessels, and EO loading / unloading • Minimization of the number of flanged connections, and operations); installation of metal strips around flanges with vent pipes • Fugitive emissions with VOC releases of EO, ethylene, and sticking out of the insulation to allow monitoring of EO methane (where methane is applied as diluent in the release; and recycle gas loop). • Installation of EO and ethylene detection systems for continuous monitoring of ambient air quality. Recommended emission prevention and control measures include the following: Terephthalic Acid (TPA) / Dimethyl Terephthalate (DMT) Gaseous emissions include off-gases from the oxidation stage • Favoring direct oxidation of ethylene by pure oxygen due to and other process vents. Because volumes of potential the lower ethylene consumption and lower off-gas emissions are typically large and include such chemicals as p- production; xylene, acetic acid, TPA, methanol, methyl p-toluate, and DMT, • Optimization of the hydrolysis reaction of EO to glycols in off gases should be effectively recovered, pre-treated (e.g., order to maximize the production of glycols, and to reduce scrubbing, filtration) if necessary depending on the gas stream, the energy (steam) consumption; and incinerated. • Recovery of absorbed ethylene and methane from the carbonate solution, prior to carbon dioxide removal, and Process Emissions from Nitrogenated Compounds recycling back to the process. Alternatively, they should be Production removed from the carbon dioxide vent either by thermal or Acrylonitrile5 catalytic oxidizers; Emission sources include gaseous vent streams from the core • Inert gas vent should be used as a fuel gas, where process plant, reactor off-gases absorber streams (saturated possible. If their heating value is low, they should be with water, and containing mainly nitrogen, unreacted routed to a common flare system to treat EO emissions; propylene, propane, CO, CO2, argon, and small amounts of 5 EIPPCB BREF (2003) APRIL 30, 2007 6 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP reaction products), crude acrylonitrile run and product storage • Nitrogen oxides and sulfur oxides (the latter in HSO plants) tanks, and fugitive emissions from loading and handling from catalytic NOX treatment units. operations. Recommended emission prevention and control measures Recommended emission prevention and control measures include the following: include the following: • Treatment of organic solvent laden streams by carbon • Gaseous vent streams from the core process plant should adsorption; be flared, oxidized (thermally or catalytically), scrubbed, or • Recycling of waste gases from the HPO and HSO plants sent to boilers or power generation plants (provided as fuel while minimizing flaring; combustion efficiency can be ensured). These vent • Waste gases with nitric oxide and ammonia should be streams are often combined with other gas streams; treated catalytically; • Reactor off-gases absorber streams, after ammonia • Aromatic solvent tanks should connected to a vapor removal, should be treated by thermal or catalytic destruction unit; oxidation, either in a dedicated unit or in a central site • Vents of oleum, phenol and ammonia storage tanks should facility; and be equipped with water scrubbers; and • Acrylonitrile emission from storage, loading, and handling • Balancing lines should be used to reduce losses from should be prevented using internal floating screens in place loading and unloading operations. of fixed roof tanks as well as wet scrubbers. Nitrobenzene Caprolactam The main air emissions from nitrobenzene production include Main emissions from caprolactam production include the vents from distillation columns and vacuum pumps, vents from following: storage tanks, and emergency venting from safety devices. All process and fugitive emissions should be prevented and • A vent gas stream, produced in crude caprolactam controlled as described in previous sections. extraction, containing traces of organic solvent; • Cyclohexanone, cyclohexanol, and benzene from the Toluene Diisocyanate6 cyclohexanone plant; The hazardous nature of toluene diisocyanate (TDI) and the • Cyclohexane from tank vents and vacuum systems from the HPO plant; other associated intermediates, line products, and by-products requires a very high level of attention and prevention. • Cyclohexanone and benzene from tank vents and vacuum systems from HSO plant; Generally, the waste gas streams from all processes • Vents from aromatic solvent, phenol, ammonia, and oleum (manufacture of dinitrotoluene (DNT), toluene-diamine (TDA), (i.e., fuming sulfuric acid - a solution of sulfur trioxide in and TDI) are treated to remove organic or acidic compounds. sulfuric acid) storage tanks; and 6 EIPPCB BREF (2003) APRIL 30, 2007 7 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Most of the organic load is eliminated by incineration. Scrubbing gas from should be continuously monitored for residual is used to remove acidic compounds or organic compounds at phosgene content; low concentration. Recommended emission prevention and • Selection of resistant, high-grade materials for equipment control measures include the following: and lines, careful testing of equipment and lines, leak tests, use of sealed pumps (canned motor pumps, magnetic • Nitric acid storage tank vent emissions should be pumps), and regular inspections of equipment and lines; recovered with wet scrubbers and recycled; and • Organic liquid storage tank vent emissions should be • Installation of continuously operating alarm systems for air recovered or incinerated; monitoring, systems for combating accidental release of • Emissions from nitration rector vents should be scrubbed phosgene by chemical reaction (e.g., steam ammonia or destroyed in a thermal or catalytic incinerator; curtains in the case of gaseous emissions), jacketed pipes, • Nitrogen oxide emissions and VOC emissions of a DNT and complete containment for phosgene plant units. plant should be reduced by selective catalytic reduction; • Isopropylamine and/or other light compounds formed by a Process Emissions from Halogenated Compounds side reaction when isopropanol is used should be Production incinerated; The main emissions from halogenated compound production • Off-gases from phosgenation, containing phosgene, lines are the following: hydrogen chloride, o-dichlorobenzene solvent vapors, and • Flue gas from thermal or catalytic oxidation of process traces of TDI, should be recycled to the process if possible. gases and from incineration of liquid chlorinated wastes; Where this is not practical, o-dichlorobenzene and • VOC emissions from fugitive sources such as valves, phosgene should be recovered in chilled condensers. flanges, vacuum pumps, and wastewater collection and Phosgene should be recycled; residues should be treatment systems and during process maintenance; destroyed with caustic soda and effluent gases should be • Process off-gases from reactors and distillation columns; incinerated; • Safety valves and sampling systems; and • Hydrogen chloride evolved from the ‘hot’ phosgenation • Storage of raw materials, intermediates, and products. stage should be recovered by scrubbers with >99.9 % efficiency; Recommended emission prevention and control measures • Phosgene in the crude product from ‘hot’ phosgenation include the following7,8: should be recovered by distillation; • Waste gas with low concentrations of diisocyanates should be treated by aqueous scrubbing; 7 The Oslo and Paris Commission (OSPAR) issued Decision 98/4 on achievable emission levels from 1,2 dichloroethane (EDC)/vinyl chloride monomer (VCM) • Unrecovered phosgene should be decomposed with manufacture. The decision is based on a BAT technical document (PARCOM, 1996) and a BAT Recommendation (PARCOM, 1996). alkaline scrubbing agents through packed towers or 8 The European Council of Vinyl Manufacturers (ECVM) issued in 1994 an industry charter to improve environmental performance and introduce emission activated carbon towers. Residual gases should be levels that were considered achievable on EDC/VCM units. The ECVM charter identifies techniques that represent good practice in the processing, handling, combusted to convert phosgene to CO2 and HCl. Outlet storage and transport of primary feedstock and final products in VCM manufacture. APRIL 30, 2007 8 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP • Consider the use of direct chlorination at high temperature conditions where flaring of the gas stream is not possible, on the to limit emission and waste production; basis of an accurate risk analysis and integrity of the system • Consider the use of oxychlorination fluidized bed reactors needs to be protected. Justification for not using a gas flaring to reduce by-products formation; system should be fully documented before an emergency gas • Use oxygen, selective hydrogenation of acetylene in the venting facility is considered. feed, improved catalysts, and reaction optimization; Before flaring is adopted, feasible alternatives for the use of the • Implement LDAR (leak detection and repair) programs; gas should be evaluated and integrated into production design • Preventing leaks from relief vents, using rupture disks in to the maximum extent possible. Flaring volumes for new combination safety valves with pressure monitoring facilities should be estimated during the initial commissioning between the rupture disc and the safety valves to detect period so that fixed volume flaring targets can be developed. any leaks; The volumes of gas flared for all flaring events should be • Installation of vapor return (closed-loop) systems to reduce recorded and reported. Continuous improvement of flaring ethylene dichloride (1,2 dichloroethane; EDC)/vinyl chloride through implementation of best practices and new technologies monomer (VCM) emissions when loading and pipe should be demonstrated. connections for loading/unloading are fully evacuated and purged before decoupling. The system should allow gas The following pollution prevention and control measures should recovery or be routed to a thermal / catalytic oxidizer with a be considered for gas flaring: hydrochloric acid (HCl) absorption system. Where practical, organic residues should be re-used as feedstock • Implementation of source gas reduction measures to the for chlorinated solvent processes (tri-per or tetra-per units); maximum extent possible; • Atmospheric storage tanks for EDC, VCM, and chlorinated • Use of efficient flare tips, and optimization of the size and by-products should be equipped with refrigerated reflux number of burning nozzles; condensers or vents to be connected to gas recovery and • Maximizing flare combustion efficiency by controlling and reuse and/or a thermal or catalytic oxidizer with HCl optimizing flare fuel / air / steam flow rates to ensure the absorption system; and correct ratio of assist stream to flare stream; • Installation of vent condensers / vent absorbers with • Minimizing flaring from purges and pilots, without recycling of intermediates and products. compromising safety, through measures including installation of purge gas reduction devices, flare gas Venting and Flaring recovery units, inert purge gas, soft seat valve technology Venting and flaring are important operational and safety where appropriate, and installation of conservation pilots; measures used in LVOC facilities to ensure that vapors gases • Minimizing risk of pilot blow-out by ensuring sufficient exit are safely disposed of. Typically, excess gas should not be velocity and providing wind guards; vented, but instead sent to an efficient flare gas system for • Use of a reliable pilot ignition system; disposal. Emergency venting may be acceptable under specific APRIL 30, 2007 9 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP • Installation of high-integrity instrument pressure protection • Maintaining proper operational conditions, such as systems, where appropriate, to reduce over pressure sufficiently high incineration and flue gas temperatures, to events and avoid or reduce flaring situations; prevent the formation dioxins and furans; • Installation of knock-out drums to prevent condensate • Ensuring emissions levels meet the guideline values emissions, where appropriate; presented in Table 1. • Minimizing liquid carry-over and entrainment in the gas flare stream with a suitable liquid separation system; Wastewater • Minimizing flame lift off and / or flame lick; Industrial process wastewater • Operating flare to control odor and visible smoke emissions Liquid effluents typically include process and cooling water, (no visible black smoke); storm water, and other specific discharges (e.g., hydrotesting, • Locating flare at a safe distance from local communities washing and cleaning mainly during facility start up and and the workforce including workforce accommodation turnaround). Process wastewater includes: units; Effluents from Lower Olefins Production • Implementation of burner maintenance and replacement Effluents from steam crackers and relevant recommended programs to ensure continuous maximum flare efficiency; prevention and control measures are the following: • Metering flare gas. • Steam flow purges (typically 10 percent of the total dilution To minimize flaring events as a result of equipment breakdowns steam flow used to prevent contaminant build-up) should and plant upsets, plant reliability should be high (>95 percent) be neutralized by pH adjustment and treated via an and provision should be made for equipment sparing and plant oil/water separator and air-flotation before discharge to the turn down protocols. facility’s wastewater treatment system; Dioxins and Furans • Spent caustic solution, if not reused for its sodium sulfide Waste incineration plants are typically present as one of the content or for cresol recovery, should be treated using a auxiliary facilities in LVOC facilities. The incineration of combination of the following steps: chlorinated organic compounds (e.g., chlorophenols) could o Solvent washing or liquid-liquid extraction for polymers generate dioxins and furans. Certain catalysts in the form of and polymer precursors; transition metal compounds (e.g., copper) also facilitate the o Liquid-liquid settler and/or coalescer for removing and formations of dioxins and furans. Recommended prevention recycling the free liquid gasoline phase to the process; and control strategies include: o Stripping with steam or methane for hydrocarbon removal; • Operating incineration facilities according to internationally o Neutralization with a strong acid (which results in a recognized technical standards;9 H2S / CO2 gas stream that is combusted in a sour gas flare or incinerator); 9 For example, Directive 2000/76/EC APRIL 30, 2007 10 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP o Neutralization with acid gas or flue gas (which will Wastewater containing hydrocarbons should be collected partition the phenols into a buoyant oily phase for separately, settled and steam stripped prior to biological further treatment); treatment in the facility’s wastewater treatment systems. o Oxidation (wet air or catalytic wet air or ozone) to oxidize carbon and sulfides/mercaptans before Effluents from Oxygenated Compounds Production neutralization (to reduce or eliminate H2S generation). Formaldehyde • Spent amine solution, used to remove hydrogen sulfide Under routine operating conditions, the silver and oxide from heavy feedstock in order to reduce the amount of processes do not produce significant continuous liquid waste caustic solution needed for final process gas treatment. streams. Effluents may arise from spills, vessel wash-water, and The used amine solution should be regenerated by steam contaminated condensate (e.g., boiler purges and cooling water stripping to remove hydrogen sulfide. A portion of the blow down that are contaminated by upset conditions such as amine wash is bled off to control the concentration of equipment failure). These streams can be recycled back into the accumulating salts; and process to dilute the formaldehyde product. • A stream of C2 polymerization product known as ‘green oil’ produced during acetylene catalytic hydrogenation to Ethylene Oxide/Ethylene Glycol ethylene and ethane, containing multi-ring aromatics (e.g. A bleed stream from the process is rich in organic compounds, anthracene, chrysene, carbazole). It should be recycled mainly mono-ethylene glycol (MEG), di-ethylene glycol (DEG) into the process (e.g., into the primary fractionator for and higher ethylene glycols, but also with minor amounts of recovery as a component of fuel oil) or should be burnt for organic salts. The effluent stream should be routed to a glycol heat recovery. plant (if available) or to a dedicated unit for glycol recovery and partial recycle of water back to the process. The stream should Effluents from Aromatics Production be treated in a biological treatment unit, as ethylene oxide Process water within aromatics plants is generally operated in readily biodegrades. closed loops. The main wastewater sources are process water recovered from condensates of the steam jet vacuum pumps Terephthalic Acid/Dimethyl Terephthalate and overhead accumulators of some distillation towers. These Effluents from the terephthalic acid process include water streams contain small quantities of dissolved hydrocarbons. generated during oxidation and water used as the purification Wastewater containing sulfide and COD may also be generated solvent. Effluents are usually sent to aerobic wastewater from caustic scrubbers. Other potential sources are treatment, where the dissolved species, mostly terephthalic unintentional spillages, purge of cooling water, rainwater, acid, acetic acid, and impurities such as p-toluic acid, are equipment wash-water, which may contain extraction solvents oxidized to carbon dioxide and water. Alternatively, anaerobic and aromatics and water generated by tank drainage and treatment with methane recovery can be considered. Waste process upsets. streams from distillation in the dimethyl terephthalate process can be burnt for energy recovery. APRIL 30, 2007 11 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Acrylic Esters • Stripping column bottoms, containing heavy components and excess water produced in the reactors. The aqueous Liquid wastes are originated at different stages of production. In stream should be treated by evaporative concentration; the acrylic acid purification, a small aqueous phase is purged from distillate should be biologically treated and the the distillation after the extraction step. This aqueous material concentrated heavy stream is burnt (with energy recovery) should be stripped before disposal both to recover extraction or recycled. solvent and minimize waste organic disposal loads. Caprolactam Bottoms from the acrylic acid product column should be stripped to recover acrylic acid, whereas the high boiling organic The liquid effluents from this production plant include the compounds are burnt. following: Organic and sulfuric wastes are produced from the esterification • Heavy bottoms from crude caprolactam extraction, in all reactor. Aqueous wastes are produced from alcohol stripping in processes using Beckmann rearrangement, containing diluted alcohol recovery. Organic heavy wastes are produced in ammonium sulfate and other sulfur compounds, which the final ester distillation. The aqueous column bottoms should should be processed into sulfuric acid; and be incinerated or sent to biological treatment. Organic heavy • A residue of finished caprolactam distillation, which should wastes should be incinerated. be incinerated. Effluents from Nitrogenated Compounds Production Nitrobenzene11 Acrylonitrile10 The nitration process is associated with the disposal of Various aqueous streams are generated from this unit. They wastewater from the neutralization and washing steps and from are normally sent to the facility’s biological treatment system reconcentration of sulfuric acid. This water can contain with at least 90 percent abatement. They include the following: nitrobenzene, mono- and polynitrated phenolics, carboxylic acids, other organic by-products, residual base, and inorganic • A purge stream of the quench effluent stream(s) containing salts from the neutralized spent acid that was present in the a combination of ammonium sulfate and a range of high- product. boiling organic compounds in an aqueous solution. Ammonium sulfate can be recovered as a crystal co- Recommended pollution prevention and control measures product or treated to produce sulfuric acid. The remaining include the following: stream containing heavy components should be treated to remove sulfur and then incinerated or biologically treated. • Neutralization of the organic phase with alkalis; The stream containing the light components should be • Extraction of the acidic contaminants from the organic biologically treated or recycled to the plant; and phase using molten salts (e.g., mixture of zinc nitrate and magnesium nitrate). Salts are then regenerated by flashing 10 EIPPCB BREF (2003) 11 Kirk-Othmer (2006) APRIL 30, 2007 12 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP off nitric acid. If necessary, the organic phase can undergo toluene), which is the most commonly used technique, a polishing neutralization; allows an almost complete removal of DNT and a reduction • The acidic contaminants can alternatively be removed by of nitrocresols to <0.5 kg/t; employing a system that utilizes solvent (e.g., benzene) • In toluene diamine preparation ammonia can be separated extractions, precipitation, distillation, and other treatments. by stripping. Low-boiling components can be separated by Residual nitric acid can be removed by a multistage distillation / stripping with steam and destroyed by countercurrent liquid–liquid extraction, and then incineration. Pre-treated process water can be re-used in reconcentrated by distillation for further use; the production process. Isopropanol, where used, can be • Multistage countercurrent solvent extraction and steam recovered for re-use. Any isopropanol in scrubber effluents stripping, usually combined. These methods can extract up can be biologically treated; to 99.5% of nitrobenzene from the wastewater, but they • In phosgenation of toluene diamines, slightly acidic leave any nitrophenols or picric acids in the water. effluents from off-gas decomposition towers, containing Concentrated extracts should be treated to recovery or traces of o-dichlorobenzene solvent, can be biologically sent to incineration; and treated or sent to a combustor with heat recovery and • Thermal pressure decomposition for removal of neutralization of halogenated effluents; and nitrophenols and picric acid in the wastewater stream • The TDI process produces water in the nitration and coming from alkaline washing. After stripping of residual hydrogenation steps. Key treatment steps normally involve nitrobenzene and benzene, wastewater should be heated concentrating the contaminants in the water stream using up to 300 °C at a pressure of 100 bars; evaporation (either single or multiple effects), recycling, or burning. The treated water stream recovered from these Toluene Diisocyanate12 concentration processes should be further treated in the Wastewater is produced from toluene nitration with inorganic facility’s biological wastewater treatment systems prior to components (sulfate and nitrite / nitrate) and organic products discharge. and by-products, namely di- and trinitrocresols. Effluents from Halogenated Compounds Production13 Recommended pollution prevention and control measures EDC/VCM plants have specific effluent streams from wash include the following: water and condensate from EDC purification (containing VCM, EDC, other volatile chlorinated hydrocarbons and non-volatile • Optimization of the process can give emissions of <10 kg chlorinated material such as chloral or chloroethanol), nitrate/ t DNT and much lower content of nitrite, before oxychlorination reaction water, water seal flushes from pumps, further removal by the biological treatment. Alternative vacuum pumps and gas-holders, cleaning water from techniques to reduce the organic load of the effluents from maintenance operations and intermittent aqueous phase from the nitration process are adsorption, extraction or stripping, the storage of crude (wet) EDC and light-ends. The main thermolysis/hydrolysis or oxidation. Extraction (e.g. with compounds in these effluents are the following: 12 EIPPCB BREF (2003) 13 EIPPCB BREF (2003) APRIL 30, 2007 13 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP • 1,2 dichloroethane (EDC) and other volatile chlorinated Hydrostatic Testing-Water organic compounds; Hydrostatic testing (hydro-test) of equipment and pipelines • Non-volatile chlorinated organic compounds; involves pressure testing with water (generally filtered raw • Other organic compounds, such as sodium formate glycol; water), to verify system integrity and to detect possible leaks. • Copper catalyst (when oxychlorination uses fluidized-bed Chemical additives (e.g., a corrosion inhibitor, an oxygen technology); and scavenger, and a dye) are often added. In managing hydrotest • Dioxin related components (with a strong affinity to catalyst waters, the following pollution prevention and control measures particles). should be implemented: Recommended pollution prevention and control measures • Using the same water for multiple tests; include the following: • Reducing the need for corrosion inhibitors and other chemicals by minimizing the time that test water remains in • Use of boiling rectors for direct chlorination to produce the equipment or pipeline; EDC in vapor form, reducing the need to remove catalyst • If chemical use is necessary, selecting the least hazardous from the effluent and EDC product; alternative with regards to toxicity, biodegradability, • Steam or air stripping of volatile chlorinated organic bioavailability, and bioaccumulation potential. compounds such as EDC, VCM, chloroform, and carbon tetrachloride. The stripped compounds can be recycled to If discharge of hydrotest waters to the sea or to surface water is the process. Stripping can be performed at atmospheric the only feasible alternative for disposal, a hydrotest water pressure, under pressure, or under vacuum; disposal plan should be prepared that considers points of • Alkaline treatment to convert non-volatile oxychlorination discharge, rate of discharge, chemical use and dispersion, by-products (e.g., chloral or 2-chloroethanol) into environmental risk, and required monitoring. Hydrotest water compounds that can be stripped (e.g., chloroform) or are disposal into shallow coastal waters should be avoided. degradable (e.g., ethylene glycol, sodium formate); • Removal of the entrained copper catalyst from the Process Wastewater Treatment oxychlorination process by alkaline precipitation and Techniques for treating industrial process wastewater in this separation by settling/flocculation and sludge recovery; and sector include source segregation and pretreatment of • Dioxins and related compounds (PCDD/F), generated concentrated wastewater streams. Typical wastewater treatment during oxychlorination fluid bed technology are partly steps include: grease traps, skimmers, dissolved air floatation or removed in the copper precipitation, together with the oil water separators for separation of oils and floatable solids; catalyst residues (metal sludge). Additional removal of filtration for separation of filterable solids; flow and load PCDD/F related compounds can be achieved by equalization; sedimentation for suspended solids reduction flocculation and settling or filtration followed by biological using clarifiers; biological treatment, typically aerobic treatment, treatment. Adsorption on activated carbon can also be for reduction of soluble organic matter (BOD); chlorination of used as additional treatment. effluent when disinfection is required; and dewatering and APRIL 30, 2007 14 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP disposal of residuals in designated hazardous waste landfills. handling, storage, and transport, as well as issues associated Additional engineering controls may be required for (i) with Ozone Depleting Substances (ODSs) are presented in the containment and treatment of volatile organics stripped from General EHS Guidelines. various unit operations in the wastewater treatment system, (ii)advanced metals removal using membrane filtration or other Wastes and Co-products physical/chemical treatment technologies, (iii) removal of Well-managed LVOC production processes do not generate recalcitrant organics and non biodegradable COD using significant quantities of solid wastes during normal operation. activated carbon or advanced chemical oxidation, (iii) reduction The most significant solid wastes are spent catalysts, from their in effluent toxicity using appropriate technology (such as reverse replacement in scheduled turnarounds of plants and by osmosis, ion exchange, activated carbon, etc.), and (iv) products. containment and neutralization of nuisance odors. Recommended management strategies for spent catalysts Management of industrial wastewater and examples of include the following: treatment approaches are discussed in the General EHS • Proper on-site management, including submerging Guidelines . Through use of these technologies and good pyrophoric spent catalysts in water during temporary practice techniques for wastewater management, facilities storage and transport to avoid uncontrolled exothermic should meet the Guideline Values for wastewater discharge as reactions; and indicated in the relevant table of Section 2 of this industry sector • Off-site management by specialized companies that can document. either recover heavy metals (or precious metals), through Other Wastewater Streams & Water Consumption recovery and recycling processes whenever possible, or Guidance on the management of non-contaminated wastewater manage spent catalysts according to industrial waste from utility operations, non-contaminated stormwater, and management recommendations included in the General sanitary sewage is provided in the General EHS Guidelines. EHS Guidelines. Contaminated streams should be routed to the treatment system Recommended management strategies for off spec products for industrial process wastewater. Recommendations to reduce include recycling to specific production units for reutilization or water consumption, especially where it may be a limited natural disposal. Guidance on the storage, transport and disposal resource, are provided in the General EHS Guidelines. ofhazardous and non-hazardous wastes is presented in the General EHS Guidelines. Hazardous Materials LVOC manufacturing facilities use and manufacture significant Lower Olefins Production amounts of hazardous materials, including raw materials and Limited quantities of solid waste are produced by steam intermediate/final products. The handling, storage, and cracking process, mainly organic sludge, spent catalysts, spent transportation of these materials should be managed properly to desiccants, and coke. Each waste should be treated on a case avoid or minimize the environmental impacts. Recommended by case basis, and may be recycled, reclaimed or re-used after practices for hazardous material management, including APRIL 30, 2007 15 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP treatment. Alternatively they may be incinerated or landfilled. the oxide process spent heat transfer fluid is most frequently Molecular sieve desiccants and acetylene hydrogenation sent to a reclaimer (for recycling) or to incineration. catalysts may be regenerated and reused. Ethylene Oxide/Ethylene Glycol Aromatics Production Spent EO catalyst, consisting of finely distributed metallic silver There is no production of hazardous waste during normal on a solid carrier (e.g., alumina), is sent to an external reclaimer operation and virtually all the feedstock is recovered into for recovery of the valuable silver. After silver reclamation, the valuable products, or as fuel gas. The most significant solid inert carrier requires disposal. wastes produced and methods for their treatment and disposal include the following: Heavy glycol liquid residues can be either reused as such or fractionated to yield marketable glycols, in order to minimize the • Spent catalyst from the liquid or gas phase hydrogenation volume to be disposed of. of olefins/diolefins and sulfur are typically processed to separate the valuable metal for re-use; Liquid residue from EO recovery section can be distilled to give • Clay from olefins removal disposed of in landfills or valuable glycols and a heavy residue containing salts (either for incinerated; sale or incineration). The stream can also be reused without • Adsorbents from xylene separations consisting of alumina distillation. or molecular sieves disposed of in landfills; Terephthalic Acid/Dimethyl Terephthalate • Sludge / solid polymerization material recovered from process equipment during maintenance activities Limited amounts of impure TPA and DMT are originated from incinerated or used on-site as a fuel source; and plant start-up and shutdown, or from maintenance operations. In • Oil contaminated materials and oily sludge (from solvents, addition, semisolid products can be originated as bottoms in bio-treatment and water filtration) incinerated with distillation operations. These wastes can be incinerated. associated heat recovery. Acrylic Esters Oxygenated Compounds Production Process solid wastes from acrylic esters manufacture are spent Formaldehyde oxidation catalysts from their replacement in scheduled turn- arounds, containing bismuth, molybdenum, vanadium, and There is negligible generation of solid wastes in the silver and possibly minor amounts of tungsten, copper, tellurium, and oxide processes under normal operating conditions. Almost all arsenic, supported on silica and polymer crusts. They are of the spent catalysts from reactors and off-gas oxidation can be collected during maintenance operations of columns, strippers, regenerated. A limited build-up of solid para-formaldehyde may vessels, and pipes. occur (principally at cold spots in equipment and pipes) and is removed during maintenance activities. Spent filters may also be generated from the purification of formaldehyde product. In APRIL 30, 2007 16 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Nitrogenated Compounds Production products by using mild operating conditions and addition of Acrylonitrile14 stabilizers; and • Collection of heavy residues from the stripper column Hydrogen cyanide co-product is produced in the acrylonitrile bottoms and/or from the quench system (basic quench) reactors and may be recovered as the overhead product from together with the catalyst fines, followed by on-site or off- the purification train. The hydrogen cyanide is either reused or site incineration. converted on-site to other products. Caprolactam Acetonitrile co-product is produced in the acrylonitrile reactors and is separated as an overhead product from the stripper Ammonium sulfate by-product is obtained from both oxidation column. Hydrogen cyanide is also present in this stream. and neutralization processes. It is typically reused as a fertilizer. Ammonium sulfate co-product is produced in the quench area of Toluene Diisocyanate the process. The ammoxidation reaction takes place in fluid bed reactors and the catalyst is retained in the reactors using Recovered hydrogenation catalyst is recycled after combinations of cyclones but some catalyst is lost and exits the centrifugation. A fraction is purged from the process and may be process through the quench system. regenerated by specialized companies, or incinerated or pre- treated prior to final disposal. Organic wastes from the Recommended management strategies include the following: manufacture of DNT, TDA, and TDI are usually incinerated. • Maximizing the re-use of hydrogen cyanide, acetonitrile, Halogenated Compounds Production 15 and ammonium sulfate byproducts; The EDC/VCM process generates liquid residues (by-products) • Incinerating hydrogen cyanide, if it cannot be recovered, in extracted from the EDC distillation train. These residues are a a flare or incinerator; mixture of chlorinated hydrocarbons, comprising compounds • Recovery of crude acetonitrile from the core unit for further heavier than EDC (such as chlorinated cyclic or aromatic purification. If recovery is not practical, burning the crude compounds) and light compounds (C1 and C2 chlorinated liquid acetonitrile stream or mixing the crude acetonitrile hydrocarbons with lower boiling points than EDC). with the absorber vent stream for burning (with energy recovery); Residues with a chlorine content of more than 60 % by weight • Recovery of ammonium sulfate as crystal, or, where can be recovered as follows: recovery is not possible, conversion to sulfuric acid; • Feedstock for chlorinated solvents such as carbon • Separation of the catalyst fines by settling or filtration and tetrachloride / tetrachloroethylene; treatment by combustion or landfill disposal; • Gaseous hydrogen chloride for re-use in the oxychlorinator; • Minimization of heavy residues by reducing the formation or of fines and catalyst losses, avoiding degradation of • Marketable hydrochloric acid solution. 14 EIPPCB BREF (2003) 15 EIPPCB BREF (2003) APRIL 30, 2007 17 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP The main solid wastes from EDC/VCM plants are spent depressurization. Guidance on noise control and minimization is oxychlorination catalyst, direct chlorination residues, and coke. provided in the General EHS Guidelines. Generic wastes also arise from wastewater treatment sludge, tank / vessel sludge, and maintenance activities. 1.2 Occupational Health and Safety Recommended management measures include the following: The occupational health and safety issues that may occur during the construction and decommissioning of LVOC facilities are • Spent oxychlorination catalyst is removed either similar to those of other industrial facilities, and their continuously (by the entrainment of fines in fluid bed management is discussed in the General EHS Guidelines. reactors), or periodically (when replacing exhausted fixed bed reactors). Depending on the process, the catalyst is Facility-specific occupational health and safety issues should be recovered in a dry form or wet form, after settling and/or identified based on job safety analysis or comprehensive hazard filtration of wastewater. Limited or trace quantities of heavy or risk assessment, using established methodologies such as a chlorinated organics (e.g., dioxins) adsorb onto waste hazard identification study [HAZID], hazard and operability study catalyst; the concentration of these contaminants should [HAZOP], or a quantitative risk assessment [QRA]. As a general determine the disposal method (usually incineration or approach, health and safety management planning should landfill); include the adoption of a systematic and structured approach for • Direct chlorination residues are generally pure or mixed prevention and control of physical, chemical, biological, and inorganic iron salts. In high temperature chlorination, radiological health and safety hazards described in the General residues are recovered with the organic heavy compounds EHS Guidelines . as a suspended solid. In low temperature chlorination, residues are recovered with wastewater and need alkali The most significant occupational health and safety hazards precipitation prior to separation by settling or filtration, occur during the operational phase of an LVOC facility and possibly with the spent oxychlorination catalyst; primarily include: • Coke is formed by the thermal cracking of EDC and • Process safety contains residual chlorinated hydrocarbons, although it • Chemical hazards does not contain PCDD/F. Coke is removed from the VCM Major hazards should be managed according to international by filtration. It also generates from decoking of the cracking regulations and best practices (e.g., OECD section; and Recommendations16, EU Seveso II Directive17 and USA EPA • Final purification of VCM may involve the neutralization of Risk Management Program Rule18). acidity using lime. This generates a spent lime waste to be disposed of. Noise Typical sources of noise generation include large size rotating 16 OECD, Guiding Principles for Chemical Accident Prevention, Preparedness and Response, Second Edition (2003) machines, such as compressors and turbines, pumps, electric 17 EU Council Directive 96/82/EC, so-called Seveso II Directive, extended by the Directive 2003/105/EC. motors, air coolers, fired heaters, flares and from emergency 18 EPA, 40 CFR Part 68, 1996 — Chemical accident prevention provisions APRIL 30, 2007 18 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Process Safety • Early detection of the release through installation of leak Process safety programs should be implemented, due to detection units and other devices; industry-specific characteristics, including complex chemical • Segregating process areas, storage areas, utility areas, reactions, use of hazardous materials (e.g., toxic, reactive, and safe areas, and adopting of safety distances19. flammable, or explosive compounds), and multi-step organic • Removing potential ignition sources; synthesis reactions. Process safety management includes the • Controlling operation and procedures and avoiding following actions: hazardous gas mixtures; • Removing or diluting the release and limiting the area • Physical hazard testing of materials and reactions; affected by the loss of containment; and • Hazard analysis studies to review the process chemistry • Developing, implementing, and maintaining a specific and engineering practices, including thermodynamics and Emergency Management Plan providing emergence kinetics; measures to be implemented to protect both operators and • Examination of preventive maintenance and mechanical local communities from potential toxic products releases. integrity of the process equipment and utilities; • Worker training; and Risks of fires and explosions are also related to oxidation • Development of operating instructions and emergency reactions (e.g., propylene oxidation reaction) and product response procedures. management. Reactors should be installed following appropriate design criteria should be used20, for instance to Fire and Explosions manage explosive mixture of product powders (e.g., terephthalic The most significant safety impacts are related to the handling acid / dimethyl terephthalate) with air. and storage of large volumes of flammable and highly flammable LVOC products (e.g., lower olefins, aromatics, Ethylene Oxide MTBE, ethylene oxide, acrylic esters and acrylic acid) at high Ethylene oxide is toxic and a human carcinogen and EO gas is temperature and pressure, combustible gases, and process flammable, even without being mixed with air, and can auto- chemicals. Explosions and fires do to accidental release of decompose explosively. The chemical properties of EO require products are the major recorded accidents in LVOC various techniques to prevent any type of losses. In particular manufacturing facilities. These events may cause significant EO/EG storage and loading design should prevent should avoid acute exposures to workers and, potentially, to surrounding ingress of air or impurities likely to react dangerously with EO, communities, depending on the quantities and types of prevent leaks, and include a vapor return system for EO loading accidentally released hazardous, volatile and flammable to minimize the gaseous streams to be handled. chemicals. The risk of explosion of the gas clouds should be minimized through the following measures: 19 These distances can be derived from safety analyses specific for the facility, considering the occurrence of the hazards or from applicable standards or guidelines (e.g., API, NFPA). 20 NFPA 654: Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids APRIL 30, 2007 19 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Acrylic Esters Nitrobenzene 25 The propylene oxidation process is a hazardous step, primarily Nitrobenzene is a very toxic substance, and very toxic due to flammability, that must be managed carefully21. Storage byproducts (e.g., nitrophenols and picric acid) are produced in and transportation of acrylic acid and esters should also be the process. In areas of high vapor concentrations (>1 ppm), carefully designed and managed, due to explosion hazards full face masks with organic-vapor canisters or air-supplied associated to uncontrolled polymerization.22,23 respirators should be used. Acrylic acid is inhibited with hydroquinone mono methyl ether, Fire and explosion hazards in nitrobenzene production are which is active in presence of air. It is easy flammable when severe, related to the possibility of run-away nitration reaction26 overheated. It should be stored in stainless steel tanks, in and to the explosivity of nitrogenated byproducts, like di- and tri contact with atmosphere of 5-21 percent oxygen, at temperature nitrobenzene, nitrophenols and picric acid. Accurate design and of 15 - 25 °C, avoiding overheating or freezing. Thawing of control of nitration reactor should be ensured. During distillation frozen acrylic acid can cause runaway polymerization; therefore, and purification, high temperatures, high concentration of thawing should be conducted under controlled conditions using byproducts, and contamination from strong acids and bases and mild heating systems. from corrosion products should be prevented to minimize risks of explosions27. Acrylonitrile and Hydrogen Cyanide 24 Hazardous properties of these two compounds require specific Toluene Diisocyanate (TDI) 28 safety considerations in their manufacturing, storage and Manufacturing of TDI involves a large number of hazardous handling. Due to its reactive and toxic nature, hydrogen cyanide substances, some in large quantities, such as chlorine, TDA, cannot be stored for periods longer than a few days. If the carbon monoxide, phosgene, hydrogen, nitric acid, nitrogen material cannot be sold or used, it must be burnt. The capability oxides, DNT, toluene, etc. to destroy all of the hydrogen cyanide produced should Contact with water and basic compounds such as caustic soda, therefore be ensured. Acrylonitrile can self-polymerize if amines, or other similar materials must be avoided, because initiators are present, and is flammable. Stabilizing agents their reaction with TDI causes the generation of heat and CO2. should therefore be added to the product, and measures taken to prevent the accidental ingress of impurities that could either The liberation of CO2 in tightly closed or restricted vessels or transfer lines may result in a violent rupture. Risk minimization strongly react or catalyze a runaway reaction. measures include the following: 21 J. R. Phimister, V. M. Bier, H. C. Kunreuther, Editors, National Academy of Engineering. Accident Precursor Analysis and Management: Reducing 25IPCS (International Programme on Chemical Safety), Environmental Health Technological Risk Through Diligence (2004) Criteria 230, Nitrobenzene. Available at http://www.inchem.org/ 22 Acrylic acid - A summary of safety and handling, 3rd Edition (2002); Intercompany Committee for the Safety and Handling of Acrylic Monomers, 26 R.V.C. Carr, Thermal hazards evaluation of aromatic nitration with nitric acid, ICSHAM Nitration Conference (1983) 23 Acrylate esters – A summary of safety and handling, 3 rd Edition, 2002 ; 27 Japan Science and Technology Agency (JST), Failure knowledge database, Intercompany Committee for the Safety and Handling of Acrylic Monomers, Explosion at a nitrobenzene distillation column due to the lowering of reduced ICSHAM pressure from power failure. Available at http://shippai.jst.go.jp/en/Search 24 EIPPCB BREF (2003) 28 EIPPCB BREF (2003) APRIL 30, 2007 20 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP • Store TDI in a dry environment using dry nitrogen or a dry • All spills should be avoided and precautions should be air pad; taken to control and minimize them; • Plug and cap all lines leading to and from storage tanks; • Adequate ventilation should be provided in all areas where • Maintain and store all fittings and line connections in a dry hazardous and toxic products are handled; and environment; • Air extraction and filtration should be provided in all indoor • Avoid to tightly close any container of TDI that has been, or areas where emissions and dust can be generated. is suspected of having been, contaminated with water; The potential for toxic releases in handling and storage of • Ensure that pure, washed DNT is not heated above 200 °C pressurized, refrigerated, and liquid hazardous products should to avoid decomposition risks; and be minimized adopting the following measures: • Very carefully handle phosgene, as follows: o Contain all phosgene operations in closed buildings; • Storage tanks should not be located close to installations o Install phosgene sensors to monitor indoor where there is a risk of fire or explosion; concentrations; • Refrigerated storage is preferred for storage of large o If phosgene traces are detected, collect and treat all quantities of products, because the initial release in the phosgene-contaminated indoor air (e.g., by alkaline case of a line or tank failure is slower than with pressurized scrubbing); and storage systems; o Install an ammonia steam curtain system surrounding • Alternative storage measures specifically applicable to the phosgene unit. Ammonia is added to the steam to liquid VCM include refrigerated storage and underground react with the phosgene in case of release. An storage. Underground storage requires special tank design alternative to this approach is building containment. and environmental monitoring considerations to manage potential for soil and groundwater contamination. Chemical Hazards In case of LVOC releases, personnel can be exposed to Potential exposures to substances and chemicals during routine concentrations dangerous for health and life. Toxic and plant and maintenance operations should then be managed carcinogenic compounds (e.g., aromatics, formaldehyde, based on the results of a job safety analysis and industrial ethylene oxide, acrylonitrile, hydrogen cyanide, nitrobenzene, hygiene survey and according to the occupational health and toluene diisocyanate, vinyl chloride, 1,2 dichloroethane, carbon safety guidance provided in the General EHS Guidelines . tetrachloride, and dioxin related components, predominantly the octo-chlorodibenzofuran generated in the oxychlorination 1.3 Community Health and Safety reaction) are present in the process and stored on site. The most significant community health and safety hazards The following measures should be implemented: associated with LVOC facilities occur during the operation phase and include the threat from major accidents related to • Gas detectors should be installed in hazard areas, potential fires and explosions in manufacturing processes or wherever possible; during product handling and transport outside the processing facility. Guidance for the management of these issues is APRIL 30, 2007 21 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP presented below and in relevant sections of the General EHS 2.0 Performance Indicators and Guidelines including: Traffic Safety, Transport of Hazardous Monitoring Materials, and Emergency Preparedness and Response. 2.1 Environment The design of the facilities should include safeguards to minimize and control hazards to the community, through the Emissions and Effluent Guidelines following: Tables 1 and 2 present emission and effluent guidelines for this sector. Guideline values for process emissions and effluents in • Identifying reasonable design accident cases; this sector are indicative of good international industry practice • Assessing the effects of the potential accidents on the as reflected in relevant standards of countries with recognized surrounding areas; regulatory frameworks. These guidelines are achievable under • Properly selecting the plant location in respect to the local normal operating conditions in appropriately designed and receptors, meteorological conditions (e.g., prevailing wind operated facilities through the application of pollution prevention directions), and water resources (e.g., groundwater and control techniques discussed in the preceding sections of vulnerability) and identifying safe distances between the this document. facilities and residential or commercial or other industrial areas; Emissions guidelines are applicable to process emissions. Combustion source emissions guidelines associated with steam • Identifying the prevention and mitigation measures required and power generation activities from sources with a capacity to avoid or minimize the hazards; and equal to or lower than 50 megawatt thermal (MWth) are • Providing information and involving the communities in addressed in the General EHS Guidelines with larger power emergency preparedness and response plans and relevant source emissions addressed in the EHS Guidelines for drills in case of major accident. Thermal Power. Guidance on ambient considerations based on Community health and safety impacts during the the total load of emissions is provided in the General EHS decommissioning of LVOC manufacturing plants are common to Guidelines . those of most large industrial facilities, and are discussed in the Effluent guidelines are applicable for direct discharges of treated General EHS Guidelines. These impacts include, among other effluents to surface waters for general use. Site-specific things, transport safety, disposal of demolition waste that may discharge levels may be established based on the availability include hazardous materials, and other impacts related to and conditions in the use of publicly operated sewage collection physical conditions and the presence of hazardous materials and treatment systems or, if discharged directly to surface after site abandonment. waters, on the receiving water use classification as described in the General EHS Guidelines. These levels should be achieved, without dilution, at least 95 percent of the time that the plant or unit is operating, to be calculated as a proportion of annual operating hours. Deviation from these levels in consideration of APRIL 30, 2007 22 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP specific, local project conditions should be justified in the and individual projects should target continual improvement in environmental assessment. these areas. Table 1. Air Emissions Guidelinesa Table 2. Effluents Guidelines Pollutant Unit Guideline Value Pollutant Unit Guideline Value pH S.U. 6-9 Particulate Matter (PM) mg/Nm 3 20 Temperature Increase °C =3 Nitrogen Oxides mg/Nm 3 300 BOD5 mg/l 25 Hydrogen Chloride mg/Nm 3 10 COD mg/l 150 Sulfur Oxides mg/Nm 3 100 Total Nitrogen mg/l 10 Benzene mg/Nm 3 5 Total Phosphorous mg/l 2 1,2-Dichloroethane mg/Nm 3 5 Sulfide mg/l 1 Vinyl Chloride (VCM) mg/Nm 3 5 Oil and Grease mg/l 10 0.5 (incineration) TSS mg/l 30 Acrylonitrile mg/Nm 3 2 (scrubbing) Cadmium mg/l 0.1 Ammonia mg/Nm 3 15 Chromium (total) mg/l 0.5 VOCs mg/Nm 3 20 Chromium (hexavalent) mg/l 0.1 Heavy Metals (total) mg/Nm 3 1.5 Copper mg/l 0.5 Mercury and mg/Nm 3 0.2 Compounds Zinc mg/l 2 Formaldehyde mg/m 3 0.15 Lead mg/l 0.5 Ethylene mg/Nm 3 150 Nickel mg/l 0.5 Ethylene Oxide mg/m 3 2 Mercury mg/l 0.01 Hydrogen Cyanide mg/m3 2 Phenol mg/l 0.5 Hydrogen Sulfide mg/m3 5 Benzene mg/l 0.05 Nitrobenzene mg/m 3 5 Vinyl Chloride (VCM) mg/l 0.05 Organic Sulfide and 1,2 Dichloroethane (EDC) mg/l 1 mg/m3 2 Mercaptans Adsorbable Organic mg/l 1 Phenols, Cresols and mg/m3 10 Halogens (AOX) Xylols (as Phenol) Toxicity Determined on a case specific basis Caprolactam mg/m3 0.1 Dioxins/Furans ng TEQ/Nm 3 0.1 a. Dry, 273K (0°C), 101.3 kPa (1 atmosphere), 6% O2 for solid fuels; 3 % O2 for liquid and gaseous fuels. Environmental Monitoring Environmental monitoring programs for this sector should be implemented to address all activities that have been identified to Resource Use, Energy Consumption, Emission have potentially significant impacts on the environment, during and Waste Generation normal operations and upset conditions. Environmental Table 3 provides examples of resource consumption indicators monitoring activities should be based on direct or indirect and energy for main products, whereas Table 4 provides indicators of emissions, effluents, and resource use applicable examples of emission and waste generation indicators. Industry to the particular project. benchmark values are provided for comparative purposes only APRIL 30, 2007 23 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Monitoring frequency should be sufficient to provide Table 4. Emissions, Effluents Waste/Co-Products representative data for the parameter being monitored. Generation Monitoring should be conducted by trained individuals following Industry Product Parameter Unit Benchmark monitoring and record-keeping procedures and using properly Alkenes t/y 2500 calibrated and maintained equipment. Monitoring data should be CO, NOx “ 200 analyzed and reviewed at regular intervals and compared with SOx “ 600 Lower Olefins VOC kg/t ethylene 0.6-10 the operating standards so that any necessary corrective Waste Water Flow m3 /h 15 actions can be taken. Additional guidance on applicable % feed/ kg/t Total hydroc. losses 0.3-0.5/5-15 ethylene sampling and analytical methods for emissions and effluents is Aromatics NOx kg/t feedstock 0-0.123 provided in the General EHS Guidelines. SO2 kg/t feedstock 0-0.146 kg/t Hydrogen cyanide 90-120 acrylonitrile Table 3. Resource and Energy Consumption Acrylonitrile Acetonitrile kg/t acrylonitrile 5-32 Industry kg/t Product Parameter Unit Ammonium sulfate 115-200 Benchmark acrylonitrile Energy Caprolactam consumption GJ/t ethylene 15-25 t/t Basf/Rashig Ammonium sulfate 2.5-4.5 Ethane feedstock caprolactam proc. Energy COD/TOC Kg/t TDI 6/2 Lower Olefins consumption GJ/t ethylene 25-40 TDI Nitrate, nitrite / Naphtha feedstock Kg/t TDI 15,10/24 sulfate Energy consumption GJ/t ethylene 40-50 Liquid residues kg/t VCM 25-40 Gas oil feedstock Oxy catalyst kg/t VCM 10-20 Aromatics Steam Kg/t feedstock 0.5-1 VCM Iron salts kg/t VCM 10-50 Formaldehyde Coke kg/t VCM 0.1-0.2 Silver/Oxide Kwh/t Electricity 100/200-225 Source: EIPPCB BREF (2003) process formaldehyde VCM Power MWh/t VCM 1.2-1.3 Source : EIPPCB BREF (2003) Governmental Industrial Hygienists (ACGIH),29 the Pocket Guide to Chemical Hazards published by the United States 2.2 Occupational Health and Safety National Institute for Occupational Health and Safety (NIOSH),30 Performance Permissible Exposure Limits (PELs) published by the Occupational Safety and Health Administration of the United Occupational Health and Safety Guidelines States (OSHA),31 Indicative Occupational Exposure Limit Values Occupational health and safety performance should be published by European Union member states,32 or other similar evaluated against internationally published exposure guidelines, sources. of which examples include the Threshold Limit Value (TLV®) occupational exposure guidelines and Biological Exposure 29 http://www.acgih.org/TLV/29 Available at: http://www.acgih.org/TLV/ and Indices (BEIs®) published by American Conference of http://www.acgih.org/store/ 30 30 Available at: http://www.cdc.gov/niosh/npg/ 31 31 Available at: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDAR DS&p_id=9992 32 32 Available at: http://europe.osha.eu.int/good_practice/risks/ds/oel/ APRIL 30, 2007 24 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Accident and Fatality Rates Projects should try to reduce the number of accidents among project workers (whether directly employed or subcontracted) to a rate of zero, especially accidents that could result in lost work time, different levels of disability, or even fatalities. Facility rates may be benchmarked against the performance of facilities in this sector in developed countries through consultation with published sources (e.g. US Bureau of Labor Statistics and UK Health and Safety Executive)33. Occupational Health and Safety Monitoring The working environment should be monitored for occupational hazards relevant to the specific project. Monitoring should be designed and implemented by accredited professionals34 as part of an occupational health and safety monitoring program. Facilities should also maintain a record of occupational accidents and diseases and dangerous occurrences and accidents. Additional guidance on occupational health and safety monitoring programs is provided in the General EHS Guidelines . 33 Available at: http://www.bls.gov/iif/ and http://www.hse.gov.uk/statistics/index.htm 34 Accredited professionals may include Certified Industrial Hygienists, Registered Occupational Hygienists, or Certified Safety Professionals or their equivalent. APRIL 30, 2007 25 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP 3.0 References and Additional Sources Carr, R.V.C. 1983. Thermal Hazards Evaluation of Aromatic Nitration with Nitric Kirk-Othmer, R.E. 2006. Encyclopedia of Chemical Technology. 5th Edition. Acid. Nitration Conference, Menlo Park, California, 27-29 July 1983. New York, NY: John Wiley and Sons Ltd. European Commission. 2003. European Integrated Pollution Prevention and National Academy of Engineering. 2004. Eds. J.R. Phimister, V. M. Bier, H. C. Control Bureau (EIPPCB) Reference Document on Best Available Techniques Kunreuther. Accident Precursor Analysis and Management: Reducing (BREF) for Large Volume Organic Chemicals. February 2003. Seville: EIPPCB. Technological Risk Through Diligence. Washington, DC: National Academies Available at http://eippcb.jrc.es/pages/FActivities.htm Press. European Commission. 2000. Directive 2000/76/EC of the European Parliament Organization for Economic Co-operation and Development (OECD). 2003. and of the Council of 4 December 2000 on the Incineration of Waste. Available Guiding Principles for Chemical Accident Prevention, Preparedness and at http://europa.eu/scadplus/leg/en/lvb/l28072.htm Response. Second Edition. Paris: OECD. Available at http://www2.oecd.org/guidingprinciples/ European Commission. 1996. Directive 96/82/EC on the control of chemical accidents (Seveso II) – Prevention, Preparedness and Response. Extended by Oslo and Paris Commission (OSPAR) for the Protection of the Marine Directive 2003/105/EC. Available at Environment of the North Atlantic. OSPAR Decision 98/4 on Emission and http://ec.europa.eu/environment/seveso/index.htm Discharge Limit Values for the Manufacture of Vinyl Chloride Monomer (VCM) including the Manufacture of 1,2-dichloroethane (EDC). London: OSPAR. European Council of Vinyl Manufacturers (ECVM). 1994. Industry Charter for the Available at http://www.ospar.org/eng/html/dra/list_of_decrecs.htm#decisions Production of VCM and PVC (Suspension Process). Brussels: ECVM. Available at http://www.ecvm.org/img/db/SPVCcharter.pdf Ullmann’s Encyclopedia of Industrial Chemistry, 2002. 6th edition. New York, NY: John Wiley and Sons Ltd. Available at http://www.wiley- German Federal Ministry for the Environment, Nature Conservation and Nuclear vch.de/vch/software/ullmann Safety (BMU). 2004. Waste Water Ordinance – AbwV. (Ordinance on Requirements for the Discharge of Waste Water into Waters). Promulgation of United Kingdom (UK) Environmental Agency. 2003. Sector Guidance Note IPPC the New Version of the Waste Water Ordinance of 17 June 2004. Berlin: BMU. S4.01- Guidance for the Large Volume Organic Chemical Sector. Bristol: Available at Environmental Agency. Available at http://www.environment- http://www.bmu.de/english/water_management/downloads/doc/3381.php agency.gov.uk/business/444304/1290036/1290086/1290209/1308462/1245952/ ?lang=_e# German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). 2002. First General Administrative Regulation Pertaining the United Nations (UN). 2003. Recommendations on the Transport of Dangerous Federal Emission Control Act (Technical Instructions on Air Quality Control – TA Goods. Model Regulations. Thirteenth revised edition. New York, NY: United Luft). Berlin: BMU. Available at Nations Publications. Available at https://unp.un.org/ http://www.bmu.de/english/air_pollution_control/ta_luft/doc/36958.php United States (US) En vironment Protection Agency (EPA). 40 CFR Part 63 — Intercompany Committee for the Safety and Handling of Acrylic Monomers National Emission Standards for Hazardous Air Pollutants, Subpart F—National (ICSHAM). 2002. Acrylate Esters – A Summary of Safety and Handling, 3rd Emission Standard for Vinyl Chloride. Washington, DC: US EPA. Available at Edition. http://www.epa.gov/epacfr40/chapt-I.info/ Intergovernmental Panel on Climate Change (IPCC). 2006. IPCC Special Report US EPA. 40 CFR Part 63 — National Emission Standards for Hazardous Air on Carbon Dioxide Capture and Storage. Geneva: IPCC. Available at Pollutants, Subpart FFFF—National Emission Standards for Hazardous Air http://www.ipcc.ch/activity/srccs/index.htm Pollutants: Miscellaneous Organic Chemical Manufacturing. Washington, DC: US EPA. Available at http://www.epa.gov/epacfr40/chapt-I.info/ International Programme on Chemical Safety (IPCS). Environmental Health Criteria 230. Nitrobenzene. Prepared by L. Davies. Joint Publication of United US EPA. 40 CFR Part 68— Chemical accident prevention and provisions. Nations Environment Programme (UNEP), International Labour Organization Washington, DC: US EPA. Available at http://www.epa.gov/epacfr40/chapt- (ILO) and World Health Organization (WHO). Geneva: WHO. Available at I.info/ http://www.inchem.org/documents/ehc/ehc/ehc230.htm US National Fire Protection Association (NFPA). 2006. NFPA 654: Standard for Japan Science and Technology Agency (JST). Failure knowledge database. the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, Available at http://shippai.jst.go.jp/en/Search and Handling of Combustible Particulate Solids. Quincy, MA: NFPA. Available at http://www.nfpa.org/aboutthecodes/AboutTheCodes APRIL 30, 2007 26 FINAL DOCUMENT Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING DRAFT Annex A: General Description of Industry Activities Large volume petroleum-based organic chemicals (LVOC) benzene concentration or extraction, and tar handling. Olefin manufacturing represents the first step of the petrochemical manufacturing plants require the capability to flare waste gases industry. LVOC manufacturing transforms refinery products, during an upset condition and certain intermittent operations. through a combination of physical and chemical operations, into The highly volatile and flammable nature of the feedstock / a variety of commodity or bulk chemicals, normally in products demands a high standard of safety, resulting in a low continuously operated, integrated plants. LVOCs are used in total hydrocarbon loss over the cracker. large quantities as raw materials in the further synthesis of higher value chemicals (e.g. solvents, plastics, and drugs). Most Aromatics36 LVOC manufacturing processes normally consist of raw material Benzene, toluene, and xylenes (BTX) are produced from three supply, synthesis, separation / refining, and handling / storage main feedstocks, namely, refinery reformates, steam cracker phases. pyrolysis gasoline (pygas), and benzene from coal tar processing. The separation of aromatics from non-aromatics Lower Olefins35 and the isolation of pure products requires use of physical Lower olefins are the largest group of commodity chemicals separation processes (e.g. azeotropic distillation, extractive within the LVOC manufacturing sector and are used for a wide distillation, liquid-liquid extraction, crystallization by freezing, range of derivatives. Feedstock range from light gases (e.g., adsorption, complexing with BF 3/HF) and product chemical ethane and LPGs) to refinery liquid products (e.g., naphtha, gas- conversion (e.g. toluene to benzene by hydrodealkylation, to oil). The use of heavier feedstock generally requires more benzene and xylene by toluene disproportionation, and xylene complex plants and generates larger quantities of co-products and/or m-xylene to p-xylene by isomerization). Ethylbenzene (e.g., propylene, butadiene, benzene). The steam cracking route can be separated by super-fractionation before xylene is the most common manufacturing process for both ethylene processing. Ethylbenzene is produced by alkylation of benzene and propylene. Steam cracking is highly endothermic with the with ethylene over an aluminum chloride or zeolite catalyst. cracking reactions taking place in pyrolysis furnaces at Impurities such as methane, hydrogen, and ethane are usually temperatures above 800 ºC. Gas compression and cleanup with combusted. The zeolite catalyst is regenerated using re- caustic soda and amines is conducted to remove acid gas and circulated nitrogen containing oxygen, and carbon dioxide is carbon dioxide. Recovery and purification of olefin products produced. Styrene is generally manufactured in a two-stage involves cryogenic separation. Ethylene is further purified to process comprising the catalytic alkylation of benzene with remove ethane by extractive distillation and acetylene by ethylene to produce ethylbenzene, followed by the catalytic catalytic hydrogenation. Integrated plants allow for energy dehydrogenation of ethylbenzene to produce styrene. The recovery. Operations directly associated with lower olefins catalysts are usually an iron oxide base including chromium and manufacturing include feed pretreatment, butadiene recovery or potassium. Another commercial process consists of oxidation of hydrogenation, gasoline heat soaking or hydro-treatment, ethylbenzene to ethylbenzene hydro-peroxide, followed by 35 EIPPCB BREF (2003) 36 Ibid. APRIL 30, 2007 27 FINAL DOCUMENT Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP reaction with propylene to give alpha phenyl ethanol and methanol with air over a crystalline silver catalyst. In the oxide propylene oxide. The alcohol is then dehydrated to styrene. process (‘Formox’) the formation of formaldehyde is obtained by Crude liquid styrene, consisting primarily of styrene and direct oxidation of methanol with excess air over a metal oxide ethylbenzene, is purified using low temperature vacuum catalyst. The methanol oxidation is an exothermic reaction. distillation with sulfur or nitrogen-based inhibitors to minimize polymerization of vinyl-aromatic compounds. MTBE (Methyl Tert-Butyl Ether) MTBE is produced by the reaction of methanol with isobutene In the two-stage cumene process, cumene is first formed by the derived from various sources. Most commercially available alkylation of benzene and propylene over a fixed-bed of zeolites. processes are comparable and consist of a reaction and a Cumene is then oxidized to cumene hydroperoxide and then refining section. decomposed with an acid catalyst (usually sulfuric acid) to produce phenol, acetone and other co-products (e.g., Ethylene Oxide / Ethylene Glycols 38 acetophenone). Phenol and acetone are then purified by Ethylene oxide (EO) is a key chemical intermediate in the distillation. Two other processes to produce phenol are the manufacture of many important products (e.g., ethylene glycols, toluene (Tolox) process (co-producing sodium benzoate) and ethoxylates, glycol ethers, and ethanol amines). the monochlorobenzene process. Emerging techniques for the Ethylene oxide is produced from ethylene and oxygen in a gas production of phenol include vacuum pyrolysis of wood waste; phase reaction carried out in a multi-tubular, fixed bed type reactive distillation in cumene production; and direct benzene reactor, with a silver oxide catalyst in the tubes and a coolant on oxidation. the shell side. Part of the ethylene feed is converted to CO2 and Oxygenated Compounds water. Reaction products (EO, carbon dioxide, and water) are Oxygenation compounds include a variety of LVOCs with removed from the circulating gas while unconverted oxygen and diverse characteristics. The following are considered ethylene are recycled back to the reactor. The recycle gas representative of this category: formaldehyde by methanol contains a diluent (e.g., methane), which allows operation at oxidation; MTBE (methyl t-butyl ether) from methanol and excess oxygen levels without causing a flammable mixture. EO isobutene; ethylene oxide by ethylene oxidation; ethylene glycol is recovered by absorption in water followed by concentration in by ethylene oxide hydration; terephthalic acid by oxidation of p- a stripper. xylene; acrylic esters by propylene oxidation to acrolein and Ethylene glycols are produced by reacting EO with water at an acrylic acid plus acrylic acid esterification. elevated temperature (typically 150 - 250°C). The main product Formaldehyde 37 is Monoethylene Glycol (MEG) but valuable co-products are Diethylene Glycol (DEG) and Triethylene Glycol (TEG). Formaldehyde is produced from methanol by catalytic oxidation, Ethylene oxide is toxic and a human carcinogen. Its gas can either under air deficiency (silver process) or air excess (oxide process). The silver process is an oxidative dehydrogenation of decompose explosively, even without being mixed with air or an 37 EIPPCB BREF (2003) 38 Ibid. APRIL 30, 2007 28 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP inert gas. The liquid phase polymerizes easily in the presence of reactor, and DMT. An alternative process used to produce DMT alkalis, mineral acids, metal chlorides, metal oxides, iron, is direct esterification of TPA. aluminum, or tin. These properties necessitate special arrangements for storage and handling. Acrylic Esters Acrylic esters are a wide class of substances, ranging from Terephthalic Acid (TPA) methyl acrylate to hexadecyl acrylate. Acrylic esters are Terephthalic acid is usually produced by liquid-phase air produced by esterification of acrylic acid, which in turn is oxidation of p-xylene in the presence of soluble manganese and produced by catalytic vapor phase oxidation of propylene with cobalt acetate catalysts and a sodium bromide promoter to form air or oxygen. Esterification plants are specialized to produce crude terephthalic acid. Acetic acid is the solvent, and oxygen in lower or higher esters, according to their boiling point (methyl to compressed air is the oxidant. Because of the highly corrosive butyl esters vs. ethylhexyl to hexadecyl). bromine – acetic acid environment, the use of titanium-lined equipment is generally required. The crystalline crude Nitrogenated Compounds terephthalic acid is collected as wet cake and dried. Solid Nitrogenated compounds include a large number of chemicals, terephthalic acid is then recovered by centrifugation or filtration, and the following is focused on acrylonitrile; caprolactam; and the cake is dried and stored prior to purification (“crude nitrobenzene; and toluene diisocyanate (TDI). terephthalic acid”, >99 percent pure). The purification step involves dissolution in hot water under pressure and the Acrylonitrile39 Acrylonitrile is an intermediate monomer used world-wide for a catalytic selection of hydrogenating contaminants. The reaction number of applications. The BP/SOHIO process accounts for 95 is highly exothermic, and water is also released. The crude percent of world-wide acrylonitrile capacity. The process is a terephthalic acid is slurried with water and heated until it vapor phase, exothermic ammoxidation of propylene in fluid bed dissolves entirely. The TPA is then hydrogenated on a carbon- reactors using excess ammonia in the presence of an air- supported Pd catalyst in liquid phase. After reaction, TPA is fluidized catalyst bed. The process has three main co-products, crystallized, centrifuged and / or filtered, and then it is dried to a namely hydrogen cyanide, acetonitrile, and ammonium sulfate. free flowing powder. Catalyst is retained in the reactors using combinations of Dimethyl Terephthalate (DMT) cyclones, although some is lost and exits the process through Most dimethyl terephthalate (DMT) is made by a stepwise the quench system. oxidation / esterification. P-xylene, together with recycled methyl Water is produced in the reaction step and rejection of water p-toluate, is passed through an oxidation reactor along with from the process is a critical part of plant design. The catalyst, where p-toluic acid and monomethyl terephthalate are concentrated, contaminated stream may be burnt or recycled to formed. It then passes to an esterification reactor, where the p- other parts of the process to maximize recovery of saleable toluic acid and monomethyl terephthalate are converted products (before burning the contaminated stream). The noncatalytically to methyl p-toluate, returned to the oxidation 39 EIPPCB BREF (2003) APRIL 30, 2007 29 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP reaction off-gases from the process absorber contains non- benzene to remove both residual nitrobenzene and nitric acid, condensables (e.g., nitrogen, oxygen, carbon monoxide, carbon while residual waste gases are scrubbed by a mixed acid loop. dioxide, propylene, propane) as well as vaporized water and An alternative process is pump nitration, where nitration actually traces of organic contaminants. An acrylonitrile plant may also takes place in the pump itself. have facilities to incinerate process residues and also to burn hydrogen cyanide. Toluene Diisocyanate (TDI) 42 Aromatic isocyanates are produced in highly integrated Caprolactam 40 production sites and this typically includes integrated phosgene Caprolactam (hexamethylene imine) is the main raw material for production. All TDI is manufactured from toluene by the the production of polyamide-6 (nylon). Caprolactam is mainly phosgene route. This continuous process involves three steps. produced via the intermediate cyclohexanone (1) Nitration of toluene where nitrating acid are formed. The (ketohexamethylene). A caprolactam production unit typically used acid is purified and concentrated for re-use and the consists of four stages. (1) Cyclohexanone (ANON) plant where mixture of dinitrotoluenes is processed in an alkaline scrubber cyclohexanone is produced catalytically from phenol and using water, or sodium carbonate solution and further fresh hydrogen. By-products are cyclohexanol and residues (tar); (2) water, and further purified by crystallization; (2) Hydrogenation Hydroxylamine phosphate oxime (HPO) plant where oxime is of dinitrotoluene to toluene diamine is a catalytic exothermic gas produced via the phosphate route; (3) Hydroxylamine sulfate / liquid / solid phase reaction. Dinitrotoluene is reduced to oxime (HSO) and caprolactam purification plant where oxime toluene-diamine (TDA) by a continuous, one or multi-stage, from the HSO route plus the oxime from the phosphate route hydrogenation process with metal catalysts. The reaction are converted to caprolactam via the sulfate route; (4) product is separated in a TDA-rich product stream, cleaned from Caprolactam finishing plant with caprolactam extraction with the residual catalyst by filtration or centrifugation, followed by a benzene and water wash removing ammonium sulfate and distillation to recycle the solvent (if used); and (4) Phosgenation organic impurities. of toluene diamine to toluene diisocyanate which is an integrated route including the manufacture of phosgene. Nitrobenzene 41 Toluene diisocyanate (TDI) is always produced by the reaction Mono-, di-, and symmetrical trinitrobenzenes are readily of phosgene with TDA in a cascade of reactors. TDI may be available by sequential nitration of benzene. A continuous produced directly from dinitrotoluene by liquid phase process, operating under similar conditions, has replaced the carbonylation with o-dichlorobenzene. traditional batch nitration process in which mixed acid (nitric and sulfuric acids) is added to a slight excess of benzene. The current production facilities are package units with nitrogen blanketing for additional safety. Each output stream passes through purging steps. Spent acid is extracted with incoming 40 Ibid. 42 EIPPCB BREF (2003) 41 Kirk-Othmer (2006) and Ullman (2002) APRIL 30, 2007 30 Environmental, Health, and Safety Guidelines LARGE VOLUME PETROLEUM-BASED ORGANIC CHEMICALS MANUFACTURING WORLD BANK GROUP Halogenated Compounds43 periodic basis (fixed-bed reactors only). EDC purification, to eliminate impurities which can inhibit EDC cracking, may entail Ethylene Dichloride (EDC) / Vinyl Chloride Monomer (VCM) various steps including washing with water and caustic to The EDC / VCM process is often integrated with chlorine and remove traces of HCl, chlorine, entrained catalyst and some ethylene production sites because of the issues related to water-soluble organics; azeotropic drying / light ends distillation; chlorine and ethylene transportation and because this heavy ends distillation; further light ends and heavy ends production chain is the largest single chlorine consumer. EDC processing; and chlorination reaction. EDC cracking is achieved (or 1, 2 dichloroethane) is synthesized by the chlorination of in heated furnaces at temperatures of approximately 500°C, ethylene (direct chlorination) or by the chlorination of ethylene where EDC splits into VCM and HCl followed by quenching, with HCl and oxygen (oxychlorination). Thermal cracking of dry, normally with cold, recycled EDC condensate, to reduce tars pure EDC produces VCM and HCl. By using both direct and heavy by-products formation. EDC feed must be more than chlorination and oxychlorination for EDC, a high level of 99.5 percent pure to reduce coke formation and fouling of the integration and by-product utilization is achieved in a balanced pyrolysis reactor and dry to prevent equipment corrosion by unit. In direct chlorination, EDC is synthesized by the exothermic hydrogen chloride. Coke build-up is periodically removed for reaction of ethylene and chlorine, catalyzed by metal chlorides. disposal. In oxychlorination, EDC and water are formed by the gaseous VCM purification is a two-stage distillation. Liquid VCM is stored phase reaction of HCl, ethylene and oxygen over a copper-salt after an optional step to remove the last traces of HCl. No catalyst either on fixed or fluidized-catalyst bed. The reaction is gaseous emissions are generated in this section and there are highly exothermic and temperature control is important to only minor quantities of waste (e.g., spent hydrogenation minimize the formation of undesirable by-products. HCl is catalyst, and spent alkaline agent for VCM neutralization). EDC / normally recycled from the EDC cracking unit and from VCM VCM production operations normally include large storage purification. Use of air increases the formation of chlorinated by- facilities. EDC and byproducts are stored in atmospheric tanks products and produces larger waste gas streams, while oxygen at ambient temperatures blanketed by nitrogen. VCM storage is significantly reduces by-products formation and volume of in spheres or tanks that can either be under pressure at ambient vented gases. Oxychlorination generates a number of waste temperature, or refrigerated at approximately atmospheric streams including impurities (e.g., mono-chloroethane and 1,1,2 pressure. Liquefied dry HCl is generally in closed system trichloroethane) as by-products from the EDC distillation section pressurized vessels at low temperatures. Atmospheric storage requiring treatment prior to emission to atmosphere; aqueous vessels and products handling are the main source of gaseous effluent from reactor outlet quenching, condensation and phase vents in the form of breathing vents, vapor displacement during separation containing small quantities of dissolved chlorinated filling, and nitrogen blanketing.44 organic compounds (chloral or chloro-ethanol) and possibly copper (dissolved or as suspended matter) coming from fines 44 Octo-chlorodibenzofuran and other dioxin related compounds are formed in the oxychlorination reactions catalyst fines (fluid bed reactors only); and spent catalyst on a as oxygen; chlorine and an organic precursor are all present at high temperatures in the presence of a catalyst. OSPAR data for two different plants showed a total formation of dioxins in the internal process of 6 g/year for a fluid bed and 40 g/year for a fixed bed reactor. However, these quantities are not emitted into the environment since further control measures are to be implemented. 43 Ibid. APRIL 30, 2007 31