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362 Lawrence K. Wang et al.

For a permit evaluation, if the applicant’s values for T and t are sufficient to achieve
c r
the required DE (compare the reported values with the values presented in Table 3), pro-
ceed with the calculations. If the applicant’s values for T and t are not sufficient, the
c r
applicant’s design is unacceptable. The reviewer may then use the values for T and t
c r
from Table 3.
T = ºF
c
t = s
r
Note: If DE is less than 98%, obtain information from the literature and incinerator vendors
to determine appropriate values for T and t .
c r
Example 3

The data necessary to perform the calculations of this example consist of HAP emission
stream characteristics previously compiled on the HAP Emission Stream Data Form
(Tables 1 and 7) and the required HAP destruction efficiency as determined by the applicable
regulations. The following are the given data for a HAP emission stream:

Maximum flow rate Q = 15,000 scfm
e
Temperature T = 120ºF
e
Heat content, h = 4.1 Btu/scf
e
Oxygen content, O = 20.6%
2
Halogenated organics: Yes No X
Based on the control requirements for the emission stream: DE = 99%.
Determine (1) the dilution air requirements of a thermal incinerator and (2) the combustion
temperature and the residence time of this incinerator.
Solution

1. If dilution air is add to the emission stream upon exit from the process, the data that
will be used in the calculations are the resulting characteristics after dilution.
Dilution air is required for emission streams with oxygen concentrations less than 20%,
and heat contents greater than 176 Btu/lb or 13 Btu/scf, which, in most cases, correspond
to flammable vapor concentrations of approx 25% of the lower explosive limit (LEL). To
convert Btu/lb to Btu/scf, multiply Btu/lb by the density of the emission stream at standard
3
conditions (typically, 0.0739 lb/ft ).
Because the oxygen content and heat content of this HAP emission stream are 20.6% and
4.1 Btu/scf, respectively, no dilution air required.
2. The required destruction efficiency is 99% and the HAP emission stream is non-
halogenated; therefore,
T = 1800ºF (Table 3)
c
t = 0.75 s (Table 3)
r
A continuous monitoring system should ensure operation at 1800ºF.

Example 4

Determine the supplementary fuel requirement of a thermal incinerator for treatment of the
HAP emission stream stated in Example 1, with the following additional technical data: