Control of Volatile Organic Compounds Emissions from Manufacturing

auxi 1i ary fuel, considering requi rements of total combustion air.
Costs of associated piping, ducting, fans, and stacks were also estimated.
E .3.l Thermal Incinerator Design Procedure
Designs of thermal incineration systems for the vari ous combinations
of waste gas streams were developed using a procedure based on heat
and mass balances and the characteristics of the waste gas in conjunction
with some engineering design assumptions. In order to ensure a 98 percent
VOC destruction efficiency, thermal incinerators were designed to
maintain a 0.75 second residence time at 870°C (1600°~).9 The design
procedure is outlined in this section.
Streams with low heat contents, which require auxiliary fuel to
ensure combustion and sometimes require air dilution or fuel enrichment
to prevent an explosive hazard, are often able to utilize recovered
waste heat by preheati ng inlet ai r, fuel , and perhaps, waste gas. The
* ,.I
design considerations for such streams are noted in the following
discussion, but the combustion calculations, etc. are not detai 1ed
because a1 1 combined streams to thermal incinerators for polymers and
resins regulatory alternatives had sufficient waste gas heating values
to combust at 870°C (1600°F) without preheating the input streams.
Therefore, only the design procedure for high heat content streams,
independently able to sustain combustion at 870°C (1600°F), is detailed
in this section.
The first step in the design procedure was to calculate the
physical and chemical characteristics affecti ng combusti on of the
waste gas stream from the model plant characteristics given in Chapter 2,
using Table E-4. In order to prevent an explosion hazard and satisfy
insurance requirements, dilution air was added to any individual or
combined waste stream with both a lower heating value between 13 and
50 Btulscf at O°C (32OF) (about 25 and 100 percent of the lower explosive
limit) and an oxygen concentration of 12 percent or greater by volume.
Dilution air was added to reduce the lower heating value of the stream
to below 13 Btulscf. (Adding dilution air is a more conservative
assumption than the alternative of adding natural gas and is probably
more realistic as other streams often have enough heat content to
sustain the combustion of the combined stream for the regulatory
a1t ernative.)