United States Environmental Protection Agency j Office of Air Quality January Planning and Standards 1981 Research Triangle Park, NC 27711 National Emission Standards for Hazardous Air Pollutants Benzene Emissions from Ethylbenzene/Styrene Plants Proposed Regulation ------- Benzene Emissions from Ethylbenzene/Styrene Plants Proposed Regulation Graphic Arts and Text Preparation: Northrop Services, Inc. Research Triangle Park, NC 27709 ------- National Emission Standards for Hazardous Air Pollutants The Clean Air Act as amended in 1977 re- quires a comprehensive national program for reducing air pollution and improving air quality. Section 112 of the Act authorizes EPA to establish National Emission Stan- dards for Hazardous Air Pollutants (NESHAPS). Hazardous air pollutants being considered for NESHAPS regulation are defined by the Act as substances (1) to which no ambient air quality standard is applicable and (2) that may reasonably be anticipated to result in an increase in mor- tality, in serious irreversible illnesses, or in incapacitating, reversible disorders. Each standard is to be set at a level that pro- vides, in the judgment of the Adminis- trator, an ample margin of safety to pro- tect the public health. NESHAPS apply to new sources immediately upon promul- gation and to existing sources within 90 days of the effective date, though under special circumstances existing sources may be given up to two years to comply. Each state may develop and submit to EPA a procedure for implementing and enforcing NESHAPS for stationary sources located within the state, which EPA will review for efficacy. EPA is now proposing a NESHAPS for benzene emissions from the process vents of ethylbenzene/styrene plants.'This standard was developed in accordance with EPA's proposed "Policy and Procedures for Identifying, Assessing, and Regulating Air- borne Substances Posing a Risk of Cancer." This policy was proposed on October 10, 1979. ------- Benzene Benzene was listed as a hazardous air pollutant by EPA on JuneS, 1977. Stu- dies of industrially- exposed workers have shown that ben- zene is causally rela- ted to the induction of a number of blood disorders. Among these diseases are leukemia (a cancer of the hematopoietic, or blood-forming, system), various cytopenias (decreased levels of formed elements in the circulating blood, such as red cells, white cells and platelets), aplastic anemia (a nonfunctioning bone marrow), and potentially-inheritable chro- mosomal aberrations. The severity of hema- topoietic diseases ranges from mild and episodic to chronic and fatal. The proposed NESHAPS would reduce the estimated maximum lifetime risk of leu- kemia to individuals exposed to benzene emissions from ethylbenzene/styrene pro- cess vents from a range of 6.2 x 10~4 to 4.4 x 10'3 to a range of 1.7 x 10'6 to 1.2 x 10~5. The estimated nationwide incidence of leukemia deaths attributable to exposure to benzene emissions from ethylbenzene/ styrene process vents (within 20 kilometers (12 miles) of ethylbenzene/styrene plants) would be reduced from a range of 0.03 to 0.2 to a range of 1.3 x 10'4 to 9.2 x 10'4 per year. ------- Ethylbenzene/ Styrene Plants Benzene is used in the production of ethylbenzene, and 99 percent of the ethylbenzene manu- factured is used to produce styrene. Ethylbenzene and styrene are considered jointly for regu lation because the processing plants are located together and are frequently integrated. (Styrene is produced only from ethylben- zene.) Polymer manufacture consumes virtually all produced styrene. Stationary sources account for 20 percent of the total benzene emissions released in the United States, with the remaining 80 percent due to mobile sources. Ethylben- zene/styrene plants are the second largest single source of benzene emissions in the chemical industry, discharging 17 percent of all benzene emitted from chemical manufacturing. Regulations to control the industry's largest single source, maleic an- hydride plants, have been proposed (see Federal Register 18 April 1980). The benzene emissions specifically affected by the proposed regulation would be those released from the vents of any of the fol- lowing equipment pieces: the alkylation reactor section, atmospheric and pressure columns, the hydrogen separation system, or vacuum-producing devices. The rule- making would apply to the 13 existing plants producing ethylbenzene and/or styrene and any new plants construc- ted. Separate standards are being developed which will cover fugitive and storage sources of benzene emissions, including ethylben- zene/styrene sources. ------- The Proposed Standard for Limiting Emissions The proposed regu- lation would apply to all process vent streams emitted at existing and new ethylbenzene/ styrene plants in the production of ethyl- benzene from ben- zene alkylation, and the production of styrene from ethylbenzene dehydrogen- ation and from ethylbenzene hydroper- oxidation. These process vent streams are defined as any continuous benzene-contain- ing gases released or having the potential of being released to the atmosphere from the alkylation reactor section, atmospheric and pressure columns, the hydrogen sep- aration system, or vacuum-producing de- vices. The regulation would result in 99 percent control of emissions from such con- tinuous process vents, reducing the total continuous process benzene emissions from the industry to 70 megagrams (76 tons) per year. The permissible limit of benzene discharges into the atmosphere would be 5 parts per million by volume on a dry basis corrected to three percent oxygen. The proposed standard would not allow emissions in excess of the numerical emission limit except when a sudden and unavoidable failure of air pollution control or process equipment occurs, or during plant startup and shutdown. These emis- sions would have to be combusted with one or more smokeless flares (or an equivalent means of control). The proposed standard would reduce estimated nationwide emis- sions due to start up, shutdown and control and process equipment failures from 133 megagrams (146 tons) per year to 21 megagrams (23 tons) per year. Owners and operators of all ethylbenzene/styrene plants would also be required to install continuous monitoring systems and report any occurrences of emissions in excess of the numerical limit, as indicated by changes in boiler operation parameters such as temperature, flue gas oxygen content and gas stream flow. ------- Achieving and Maintaining the Standard The proposed stan- dard is based on the best available tech- nology for reducing benzene emissions, { considering environ- V ) mental, economic ^—->^^ -r—\ and energy impacts. X/ ^ It can be achieved through add-on controls, such as boilers and process heaters, which are currently used at all ethylbenzene/styrene plants as part of the production process. These con- trols are not specifically required by the proposed standard, but have been proven as viable means to curb emissions. These con- trols would involve routing the vacuum col- umn vents, the atmospheric and pressure column vents, the alkylation reactor vents, and the hydrogen separation vent to an existing boiler or process heater to attain a 99-percent emission reduction. Continuous monitoring systems that would monitor certain process parameters would be used to indicate occurrences of emissions in excess of the numerical emission limit. ------- Impacts Environmental: Na- tionwide annual re- ductions of benzene emissions from eth- ylbenzene/styrene plants, operating at full capacity, would be 2,009 megagrams per year (from 2,100 to 91 megagrams) or 2,210 tons (from 2,310 to 100tons). These reductions would be achieved with no significant increase in waste water or effluent discharge by ethyl- benzene/styrene plants. Noise and thermal radiation associated with the use of flares are negligible. Energy: Due to recovered heat energy, a 99 percent reduction in continuous benzene emissions would result in a small total na- tionwide energy savings, equivalent to ap- proximately 0.1 percent of the current na- tionwide ethylbenzene/styrene fuel re- quirements. Economic/Industrial: Capital costs for achieving the 99-percent level of control range from zero to $686,000 per plant, ac- counting for additional piping and controls for existing burners. Total annualized costs, including operating and maintenance costs, annualized capital costs, and recovered ma- terial and fuel credits, would range from a cost of $68,750 to a savings of $140,000 per plant. The potential maximum styrene price increase would be as much as 0..27 percent. ------- Public Participation A public hearing on the proposed regu- lation is scheduled for February 5,1981 beginning at 9a.m. at EPA Administra- tion Building Audi- torium, Research Triangle Park, NC 27711. Individuals who wish to present additional data, views, or other comments concerning this NESHAPS regulation are invited to participate. If you wish to speak atthe meeting, contact Ms. Naomi Durkee, Emission Standards and Engineering Divi- sion (MD-13), U.S. Environmental Protec- tion Agency, Research Triangle Park, North Carolina 27711, telephone 919/541-5331 by January 29, 1981. Written comments will be accepted on or before March 7, 1981 and should be submitted in duplicate and addressed to Central Docket Section (A-130), Atten- tion: Docket Number A-79-49 U.S. Envi- ronmental Protection Agency, West Tower Lobby, Gallery 1, Waterside Mall, 401 M Street, SW, Washington, DC 20460. The docket; contains all information considered by EPA during the development of this standard and is open for inspection. The background document for the proposed standard may be obtained from the EPA Library (MD-35), Research Triangle Park, North Carolina 27711, telephone 919/541 -2777. Refer to: Benzene Emissions from the Ethylbenzene/ Styrene Industry—Back- ground Information Document for Pro- posed Standards (EPA 450/3-79-035a). Supporting documents on benzene health effects may also be obtained: Assessment of Health Effects of Benzene Germane to Low-Level Exposures (EPA 600/1-78-061), Assessment of Human Exposures to Atmo- spheric Benzene (EPA450/3-78-031), and Carcinogen Assessment Group's Report on Population Risk to Ambient Benzene Exposures (EPA 450/5-80004). ------- Status of The proposed standard was published in scheduled for February 5, 1981, and the Regulation the Federal Register (FR 45 83448) on final regulation is scheduled for publication December 18 , 1980. A public hearing is in January, 1982. ------- |