Control of Volatile Organic Compounds Emissions from Manufacturing

cmmrci a1 1y available size of .l .Ol m3 (35.7 ft3) based on vendor informati
and a maximum shop-assembled unit size of 205 m3 (7,238 ft3) .8
The design procedure would allow for pretreating of combustion air,
natural gas, and when permitted by insurance guidelines, waste gas using
a recuperative heat exchanger in order to reduce the natural gas required
to maintain a 870°C (1600°F) combustion temperature. However, a1 1
streams to thermal incinerators costed for these polymers and resins
had sufficient waste gas heating values to combust at 870°C (1600°F)
without preheating the input streams. If a plant had a use for it,
heat could be recovered. (In fact, a waste heat boiler can be used to
generate steam, generally with a net cost savings.)
5.1.1.2 Thermal Incinerator Costing. Thermal inci nerator purchase
costs were taken directly from the IT Enviroscience graph for the calculated
combust~on chamber vol ume.5 (Essenti a1 l y equi val ent purchase costs
would be obtained by using data from the GARD manual .2) A retrofit
Installation cost factor of 5.29 was used based on the Enviroscience
document (see Table 5-2) .9
The installed cost of one 150-ft. duct to the incinerator and its
associated fan and stack were also taken directly from the IT Enviroscience
I
study.10 A minimum cost of $70,000 (December 1979 dollars) was assumed .
for waste gas streams with flows below 500 scfm. The costs of piping or
ducting from the process sources to the 150-ft. duct costed above were
estimated for 70 feet long "source legs."ll For flow's less than 700 scfm,
an economic pipe diameter was calculated based on an equation in the
Chemi ca1 Engi neer ' s ~andbookl~ and simp1 ified as suggested by
~hontos.13~14~15 The next larger size (inner di ameter) of schedule
40 pipe was selected unless the calculated size was within 10 percent of I
the size interval between the next smaller and next larger standard
sizes. For flows of 700 scfm and greater, duct sizes were calculated
assuming a velocity of 2,000 fpm for flows of 60,000 acfm or less and
5,000 fpm for flows greater than 60,000 acfm. Duct sizes that were
multiples of 3-inches were used. (See Section E.6 for detailed design
and cost procedures for piping and ducting.)
Piping costs were based on those given in the Richardson Engineering
Services Rapid Construct ion Estimati ng Cost system16 as combi ned for
70 ft. source legs and 500 ft. and 2,000 ft. pipelines for the cost
4
I
1
I