&EPA
                                United States
                                Environmental Protection
                                Agency    .

                                Research antyDevelopment
                                 Industrial Environmental Research
                                 Laboratory
                                 Research Triangle Park NC 27711
                                EPA-600/S7-81-121  Sept 1981
Project  Summary
                                Control  of  Hydrocarbon
                                Emissions  from  Gasoline
                                Loading  by  Refrigeration
                                Systems

                                W. Battye, P. Brown, D, Misenheimer, and F. Seufert
                                  The capabilities of refrigeration
                                systems operated at three tempera-
                                tures to control volatile organic
                                compound  (VOC) emissions  from
                                truck loading at bulk gasoline terminals
                                were investigated in this study. Elec-
                                tricity requirements and relative costs
                                associated with systems operating at
                                each temperature were calculated.
                                  Achievable VOC emission  rates
                                were calculated for refrigeration sys-
                                tems cooling various gasoline/air
                                mixtures to temperatures of -62°C (-
                                80°F). -73°C |-100°F), and -84°C (-
                                120°F) by estimating vapor-liquid
                                equilibrium compositions for VOC/air
                                mixtures. Equilibrium compositions
                                were estimated using a computer
                                simulation program and the Soave-
                                Redlich-Kwong  and Peng-Robinson
                                methods of predicting thermodynamic
                                properties of mixtures. Emission rates
                                were calculated for inlet streams
                                containing vapors from low- and high-
                                volatility gasolines, at concentrations
                                of 15, 30, and 50 percent by volume
                                (22.5, 45, and 75 percent measured
                                as propane). Predicted VOC emission
                                rates for systems cooling various inlet
                                streams to -62°C ranged from 48 to
                                59 mg VOC/I  of gasoline loaded.
                                Predicted VOC emissions were  21 to
                                28 mg/l loaded for systems operating
                                at -73°C and 8.7 to 12 mg/l loaded
                                for systems operating at -84°C.
                                  Compressor electrical requirements
                                and relative capital costs for systems
                                operating at the above temperatures
                                were estimated for model systems
                                using  the results of the computer
                                simulation. Compressor electricity
                                requirements  ranged from 0.11 to
                                0.45 Whr/l loaded depending upon
                                the inlet VOC concentration and the
                                outlet temperature. The electricity
                                requirement to cool vapors to -84°C
                                was estimated to be 54 to 77 percent
                                greater than the requirement to cool
                                vapors to  -62°C,  depending on the
                                organic content of the inlet stream.
                                The electricity requirement to cool
                                vapors to -73 °C is estimated to be 23
                                to 36 percent greater than to cool
                                vapors to -62°C. The capital cost to
                                build a system designed to cool vapors
                                to -84°C is estimated to be about 9
                                percent higher than the capital cost to
                                build a system designed to operate at
                                -73°C, which is estimated to be about
                                12  percent higher than the cost to
                                build a system designed to operate at
                                -62°C.
                                 . This Project Summary was devel-
                                oped by EPA's Industrial Environmen-
                                tal Research Laboratory. Research
                                Triangle Park.  NC, to announce key
                                findings of the research project that is
                                fully documented in a separate report
                                of the same title (see Project Report
                                ordering information at back).

                                Introduction
                                  The primary  objective of this study
                                was to investigate the capabilities of

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refrigeration systems operated  at
various temperatures to control volatile
organic compound emissionsfrom truck
loading at bulk gasoline terminals. A
secondary objective was to estimat&the
electricity requirements and the relative
capital costs  of  systems operated  at
various temperatures.
  Achievable emission rates for refrig-
eration systems were calculated  by
estimating vapor-liquid equilibrium
compositions for hydrocarbon/air mix-
tures  at three system operating tem-
peratures: -62°C, -73°C, and  -84°C.
Equilibrium compositions were deter-
mined using  a computer simulation
program and the Soave-Redlich-Kwong
and Peng-Robinson methods of  pre-
dicting the thermodynamic properties of
mixtures and mixture components.
These methods were also used  to
predict the amount of  heat removal
required to cool  hydrocarbon/air  mix-
tures  to  the  three  system operating
temperatures. Model  refrigeration
systems were  designed based  on the
predicted heat removal requirements.
Electricity requirements and relative
capital costs  were estimated for the
model systems.
  Volatile organic compounds (VOC) are
emitted from bulk gasoline terminals as
a result of the displacement of gasoline-
laden  vapors from trucks during truck
loading. These emissions are generally
controlled by  ducting the displaced
vapor—a mixture  of  air and  hydro-
carbons—to a  system  which removes
the hydrocarbons. One of the techniques
which can  be used to  control these
emissions is refrigeration. In refrigera-
tion systems,  the gasoline-laden air is
cooled to cryogenic temperatures in
order  to condense the gasoline vapors.
  Refrigeration systems currently  in
use to control gasoline  vapor emissions
operate at temperatures between -46°C
and -84°C. Emissionsfrom refrigeration
systems  have  been tested and range
from 30 to 130 mg/l of vapor entering
the refrigeration control system.  Test
data  are not available to accurately
determine the relationship  between
emissions from  refrigeration systems
and system operating  temperature, or
other  parameters.
  In this  study the  emission reduction
capabilities and electricity requirements
of refrigeration systems used to control
VOC emissions from gasoline terminals
were  determined as functions of the
refrigeration system operating temper-
ature  and the  concentration of hydro-
carbons  entering the' refrigeration
system. In addition, relative capital
costs were estimated for refrigeration
systems designed to operate at different
temperatures.

Discussion and Procedure
  Achievable VOC emission rates were
calculated for systems cooling various
gasoline vapor/air mixtures to temper-
atures of -62°C, -73°C, and -84°C. The
control systems studied would first cool
the mixtures to 4.4°C in a precooler in
order to remove most of the moisture
present.  Vapors from the  precooler
would then be cooled to -62°C, -73°C,
or  -84°C  in  the  main  condenser.
Calculations  of  controlled emission
rates and electricity requirements were
performed for inlet streams containing
typical  low- and high-volatility gasoline
vapors  in concentrations of 15, 30, and
50 percent by volume.
  The lowest achievable emission rate
for refrigeration to a given temperature
occurs  when the vapor and liquid
streams leaving the main condenser are
at thermodynamic equilibrium. Thus,
thelowest achievable emission rate for
a given operating temperature can be
calculated by determining the equilibrium
composition of the vapor phase at that
temperature. Equilibrium compositions
were estimated using a computer simu-
lation program and the Soave-Redlich-
Kwong and Peng-Robinson methods of
predicting thermodynamic properties of
mixtures. Heat removal requirements to
cool gasoline-laden vapors to cryogenic
temperatures were also estimated
using these methods. The predicted
heat removal  requirements were used
to design model refrigeration systems,
which  are  parametric descriptions of
refrigeration systems including equip-
ment sizes, and refrigerant and  heat
flow rates. The  model  refrigeration
systems were used to estimate electricity
requirements  to cool the inlet vapor
mixtures  under study to cryogenic
temperatures. The costs of components
were estimated for the model systems
designed to treat mixtures containing
30 percent by volume hydrocarbons, in
order to  estimate the relative  capital
costs of systems designed to cool vapors
to various temperatures.

Results
  Achievable emission  rates were
calculated in terms of the  mass of VOC
emissions  per unit volume of vapor
entering the control system. Assuming
that the  trucks being loaded and the
ducts carrying vapors from the trucks to
the control system are vapor-tight, the
volume  of  vapor entering the control
system  is equal to the volume of
gasoline loaded. The calculated  emis-
sion rates can be expressed in terms of
mg VOC/I  gasoline  loaded. Note that
VOCs are defined by EPA to include any
organic compound which participates in
atmospheric photochemical reactions.
With  the  exception of methane  and
ethane, all hydrocarbons present in
gasoline vapors are  considered VOCs.
Thus, VOC emission  rates calculated in
this study are emission rates of non-
methane non-ethane hydrocarbons.
  Figure 1  illustrates the dependence of
VOC  emissions on  condenser  outlet
temperature  for inlet  air  streams
containing low-volatility gasoline vapors
in concentrations of 15, 30, and 50
percent  by  volume. Figure 2 illustrates
the dependence of VOC emissions on
condenser  outlet temperature for inlet
streams containing 15, 30 and 50
percent  by volume high-volatility gas-
oline  vapors. Low-volatility gasolines
are generally loaded in the summer, and
high-volatility gasojines are  generally
loaded in the winter.  Therefore, for inlet
streams containing low-volatility vapors,
emissions were calculated assuming an'
inlet temperature of  27°C; and for inlet
streams with high-volatility gasoline
vapors, emissions  were calculated
assuming an inlet temperature of 4.4°C.
  Predicted VOC emission  rates for
systems cooling various inlet streams to
-62°C ranged from 48 to 59 mg VOC/I
of gasoline loaded,  depending on the
percentage of hydrocarbons in the inlet
stream.  Predicted VOC emissions were
21  to 28  mg/l loaded  for systems
operating at -73°C and 8.7 to 12 mg/l
loaded for systems operating at -84°C.
As shown in Figures 1  and 2,  the
logarithm of the VOC emission rate is
approximately  proportional to the re-
ciprocal of the  system  operating terrf-
perature  for a given set of inlet
conditions.
  Predicted compressor electricity
requirements ranged from 0.11 to 0.45
Whr/l loaded  depending on the inlet
VOC  concentration and the outlet
temperature. The electricity required to
cool vapors to -84°C is estimated to be
54 to 77  percent greater than that
required to  cool vapors to -62°C,
depending on the hydrocarbon content
of the  inlet  stream. The electricity
requirement to cool  vapors to -73°C is
estimated to be 23 to 36 percent greater.
than that to cool vapors to -62°C.  ThJI
capital cost to build a system designed

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       W. Battye, P. Brown, D. Misenheimer, andF. Seufert are with GCA/Technology
         Division. 500 Eastowne Drive, Chapel Hi/I, NC 27514.
       Samuel L. Rakes is the EPA Project Officer fsee below).
       The complete report, entitled "Control of Hydrocarbon Emissions from Gasoline
         Loading by Refrigeration Systems," (Order No. PB 81-240 335; Cost: $8.OO,
         subject to change) will be available  only from:
              National Technical Information Service
              5285 Port Royal Road
              Springfield. VA 22161
              Telephone:  703-487-4650
       The EPA Project Officer can be contacted at:
              Industrial Environmental Research Laboratory
              U.S. Environmental Protection Agency
              Research Triangle Park, NC 27711
      U S GOVERNMENT PRINTING OFFICE. 1981 — 757-012/7357
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300


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