Control of Volatile Organic Compounds Emissions from Manufacturing

Install ed piping and ducting costs were estimated as noted for
thermal incinerators (see Appendix E.6). Instal 1 ed costs were put on a
June 1980 basis using the fo11 owi ng Chemical Engi neeri ng Pl ant Cost
Indices: the overall index for f1 ares; the pipes, val ves, and fittings
index for piping; and the fabricated equipment index for ducting.
Annualized costs were calculated using the factors presented in Table 5-3.
5.1.3 Catalytic Incinerator Design and Cost Basis
Catalytic incinerators are general 1 y cost effective VOC control
devices for low concentration streams. The catalyst increases the
chemical rate of oxidation all owing the reaction to proceed at a 1 ower
energy 1eve1 (temperature) and thus requi ring a small er oxidation chamber,
1 ess expensive material s, and much 1 ess auxil iary fuel (especial 1 y for
1 ow concentration streams) than requi red by a thermal incinerator. The
primary determinant of catalytic incinerator capital cost is vol umetric
fl ow rate. Annual operating costs are dependent on emi ssion rates,
mol ecul ar weights, VOC concentration, and temperature. Catalytic
inci neration in conjunction with a recuperative heat exchanger can
reduce overall fuel requirements.
5.1 -3.1 Catalytic Incinerator Design. The basic equipment component
of a catalytic incinerator incl ude a bl ower, burner, mi xi ng chamber,
catalyst bed, an optional heat exchanger, stack, controls, instrumentation,
and control panels. The burner is used to preheat the gas to catalyst
temperature. There is essentially no fume retention requirement. The
.preheat temperature is determined by the VOC content of the combined
waste gas and combustion air, the VOC destruction efficiency, and the
type and amount of catalyst required. A sufficient amount of air must
be available in the gas or be supplied to the preheater for VOC combustion.
(All the gas streams for which catalytic incinerator control system
costs were developed are dilute enough in air and therefore require no
additional combustion air.) The VOL components contained in the gas
streams incl ude ethyl ene, n-hexane, and other easily oxidi zabl e components.
These VOC components have catalytic ignition temperatures below 315°C
(600°F). The catalyst bed out1 et temperature is determi ned by gas VOC-*
content. Catalysts can be operated up to a temperature of 700°C (1,300°F).
However, continuous use of the catalyst at this high temperature may
cause accel erated thermal aging due to recrystal 1 ization.