Control of Volatile Organic Compounds Emissions from Manufacturing

(1) styrene in steam and .(2) sytrene in air from the continuous polystyrene
model plant.
E.5.1 Surface Condenser Design
The condenser system evaluated consists of a shell and tube heat
exchanger with the hot fluid in the shell side and the cold fluid'in
the tube side. The system condensation temperature is determined from
. the total pressure of the gas and vapor pressure data for styrene and
steam and sytrene in air. As the vapor pressure data are not readily
available, the condensation temperature is estimated for styrene in
steam by trial-and-error, and for styrene in air by a regression equation
.
of available data points26 using the Clausius Clapeyron equation which
relates the stream pressures to the temperatures. The total pressure
of the stream is equal to the vapor pressures of individual components
at the condensation temperature, Once the condensation temperature is
known, the total heat load of the condenser is determined from the
latent heat contents of styrene and steam and, for styrene in air, from
the latent heat content of the condensed sytrene and the sensible heat
changes of styrene and air. Table E-12 shows the procedure for calculating
. the heat load of a condensation system for styrene in ai r. The design
requirements of the condensation system are then determined based on
the heat load and stream characteristics. The coolant is selected
based on the condensation temperature, The condenser system is sized
based on the total heat load and the overall heat transfer coefficient
which is established from individual heat transfer coefficients of the
gas stream and the coolant. An accurate estimate of individual coefficients
can be made using such data as viscosity and thermal conductivity of
the gas and coolant and the standard sizes of shell and tube systems to
be used.
For styrene in steam, no detailed calculations were made to determine
the individual and overall heat transfer coefficients. Since the
streams under consideration contain 1 ow amounts of styrene, the overall
heat transfer coefficient is est imated based on pub1ished data for
steam.
For styrene-i n-ai r, refrigerated condenser systems were designed
according to procedures for calculating she1 1 side28 and tube side29
heat transfer coefficients and according to condenser30 and refri gerant31.32