Control of Volatile Organic Compounds Emissions from Manufacturing

The catalyst bed size requi red depends upon the type of catalyst used
and the VOC destruction efficiency desi red. Heat exchanger requi rements
are determined by gas inlet temperature and preheater temperature. A
minimum practical heat exchanger efficiency is about 30 percent; a maximum
of 65 percent was assumed for this analysis. Gas temperature, preheater
temperature, gas dew point temperature, and gas VOC content determine the'
maximum feasible heat exchanger efficiency. A stack is used to vent the '
flue gas to the atmosphere.
Fuel gas requi rements were cal cul ated based on the heat requi red
for a preheat temperature of 315OC (600°F), plus 10 percent for auxiliary
fuel. The fuel was assumed to be natural gas, although oil (No. 1 or 2)
can be used. Electricity demand was based on pressurk drops of 4 inches '
I
water for systems without heat recovery and 10 inches witell for systems
with heat recovery, a conversion rate of 0.0001575 hplin. water, 65 percen
motor efficiency, and 10 percent additional electricity requi red for
instrumentation, controls, and mi scel laneous. A catalyst requi rement of
2.25 ft3/1,000 scfm was assumed for 98 percent efficiency.25 Catalyst
rep1 acement every three years was assumed.
5.1.3.2 Catalytic Incinerator Costing. Cal cul ations for capital
cost estimates were based on equipment purchase costs obtained from
vendors for all basic components and the application of direct and
indi rect cost factors .25326,27 Purchase cost equations were devel oped
based on vendor third quarter 1982 purchase costs of catalyst incinerator
systems with and without heat exchangers for sizes from 1,000 scfm to
50,000 scfm. The cost data are based on carbon steel material for
incinerator systems and stainless steel for heat exchangers. Catalytic
fnclnerator systems of gas volumes higher than 50,000 scfm can be
estimated by considering two equal volume units in the system. A minimum
available unit size of 500 scfm was assumed28~29; the instal led cost of
this minimum size unit, which can be used without addition of gas or
air for stream flows greater than about 150 scfm29, was estimated to be
$53,000 (June 1980). Heat exchangers for small size systems are costly
and may not be practical. The direct and indirect cost component
factors used for estimati ng capital costs of catalytic inci nerator
systems with no heat exchangers and for heat exchangers were presented
in Table 5-2. Installed costs of piping, ducts, fans, and stacks were
I
I
I