Page 250 - Air Pollution Control Engineering

05_chap_wang.qxd 05/05/2004 3:46 pm Page 229
Wet and Dry Scrubbing 229

1. Reported removal efficiency, RE reported = %
2. Emission stream flow rate, Q = scfm
e
3. Temperature of emission stream, T = °F
e
4. Molecular weight of emission stream, MW = lb/lb mol
e
5. Hazardous air pollutant, HAP = (chemical name and formula)
6. HAP concentration, HAP = ppmv
e
7. Solvent used (absorbent or scrubbing agent) =
8. Slope of the solubility equilibrium curve (pollutant in absorbent), m =
9. Solvent (absorbent) flow rate, L gal = gal/min
10. Density of emission stream, D = lb/ft 3
e
11. Schmidt number, for HAP/emission stream and HAP/solvent systems:
a. Sc =
G
b. Sc =
L
12. Solvent (absorbent) properties:
a. Density, D = lb/ft 3
L
b. Viscosity, µ = cP (centipoise)
L
13. Type of packing = (trade name, size, supplier)
14. Packing constants:
a = b = c =
d = e = Y =
s = g = r =
15. Column (absorber tower) diameter, D = ft
column
16. Tower height (packed depth), Ht = ft
column
17. Pressure drop (tower total including packed bed), P = in. of
total
water
Example 2
A step-by-step procedure for determining solvent flow rate required in a packed tower wet
scrubbing system follows.

Solution
A. Assume a value for the absorption factor, AF = 1.6.
Determine m from published equilibrium data for the HAP/absorbent (solvent) sys-
tem. (1,3,6)
m =
Using Eq. (3) with
Q = scfm
e
G = 0.155 Q (3)
mol e
G = lb-mol/h
mol
B. Using Eq. (2),
L = (1.6)(m)(G ) (2)
mol mol
L = lb-mol/h
mol
C. Using Eq. (5)
L = 0.036L (5)
gal mol
L = gal/min
gal