Page 53 - Air Pollution Control Engineering

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Air Quality and Pollution Control 33

W = W + W + ... + W (36)
e,l e1,l e2,l en,l
where W is the particulate loading for the combined gas stream (lb/h).
e,l
Equation (37) shows how particulate loading in the combined gas stream is converted
from lb/h to g/acf:
)(
W = W ( Q )(7 000 g 1b h 60 min) (37)
,
,
eg e,l e a
,
where W is the particulate loading for the combined gas stream (g/acf).
e,g
7.5. Heat Content Calculations
Utilizing the heat of combustion for each component in gas stream 1, the heat con-
tent of the gas stream can be calculated using
n
001) ∑
h = ( . y h (38)
e1 e i ei
,
1
1,
i = 1
where h is the heat content in gas stream 1 (Btu/scf), y is the volume percent of com-
e1 e1,i
ponent i in gas stream 1 (vol%), h is the heat of combustion of component i in gas
el,i
stream 1 (Btu/scf) (see Table 6), and n is the number of components in gas stream 1.
The combined gas stream heat content is determined from the heat content of the
individual gas streams, with emission streams as follows
m
.
H = (001 ) ∑ y h ej (39)
ej
e
j = 1
where H is the combined emission stream heat content (Btu/scf), y is the volume
e ej
percent of stream j in the combined gas stream (vol%), h is the heat content of gas
ej
stream j in the combined gas stream (Btu/scf) (see previous discussion), and m is the
number of individual gas streams in the combined gas stream. To convert the heat con-
tent of a stream to Btu/lb, multiply the heat content of a stream Btu/scf by the density
3
of the emission stream at SC (typically 0.0739 lb/ft ).
7.6. Dilution Air Calculations
Dilution air can be used to decrease the heat content of the emission stream. Equation
(40) is used to determine the quantity of dilution air (Q ) required to lower the heat
d
content of an emission stream (18):
e ( [
Q = Q h h ) − 1 ] (40)
d e d
where Q is the dilution airflow rate (scfm), h is the emission stream heat content
d e
before dilution (Btu/scf), h is the emission stream heat content after dilution (Btu/scf),
d
and Q is the emission stream flow rate before dilution (scfm). After the dilution quan-
e
tity is determined, the concentrations of the various components and flow rate of the
emission stream must be adjusted as follows:
[
d (
2(
O = O hh ) + 21 1 − hh e)] (41)
2,d d e