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

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Benzene Emissions from
Ethylbenzene/Styrene Plants
Proposed Regulation
                    Graphic Arts and Text Preparation:
                    Northrop Services, Inc.
                    Research Triangle Park, NC 27709

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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.

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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.

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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.

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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.

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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.

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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.

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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).

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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.

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