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Condensation 323

3. Determine the partial pressure of the HAP in the condenser effluent, assuming the
pressure in the condenser is constant and at atmospheric.
4. Determine the condensation temperature, T .
con
5. Select an appropriate coolant.
Solution
1. These stream characteristics are taken from Emission Stream 6 in Table 7.
Maximum flow rate, Q = 2000 scfm
e
Temperature, T = 90ºF
e
HAP = styrene
HAP concentration, HAP = 13,000 ppmv (corresponding to saturation conditions)
e
Moisture content, M = negligible
e
Pressure, P = 760 mm Hg
e
2. Based on the control requirements for the emission stream,
Required removal efficiency, RE = 90 %
3. Using Eq. (1) and Fig. 4,
(
HAP = 13 000 ppmv styrene)
,
e
RE = 90%
 (1 − 0 01 RE) 


.
P = 760   HAP × 10 −6 (1)
partial − ( RE × 10 HAP )] e
−8
 [  1 e 
[ { )] [ −8 )]} −6
×
P partial = 760 1 −(0 01 90 1 −(90 × 10 ×13 000 13 000 ×10
.
,
,
.
P =10 mm Hg
partial
4. For styrene, the value of 1/(T + 460) corresponding to 1.0 mm Hg in Fig. 4 is about
con
0.00208. Solve for T = 20ºF. Based on T = 20ºF, the appropriate coolant is a
con con
brine solution. Assume that the brine solution is a 29% (wt) calcium chloride solu-
tion, which can be cooled down to −45ºF (see ref. 3).
Example 2
The air emission stream documented in Table 7 is to be treated by a condenser. Determine
the following condenser design parameters:
1a. The moles of HAP in the inlet emission stream, HAP
e,m
1b. The moles of HAP in the outlet emission stream, HAP
o,m
1c. The moles of HAP condensed, HAP
con
2a. The HAP’s heat of vaporization, ∆H
2b. The enthalpy change associated with the condensed HAP, H
con
2c. The enthalpy change associated with the noncondensible vapors (i.e., air), H
noncon
3. The condenser heat load, H
load
The following technical data are known:
Q = 2000 scfm
e
T = 90ºF
e
HAP = styrene
HAP = 13,000 ppmv
e