Gas Emission Control - Mathematics and Statistics for the Environment - page 459

F = Packing factor (dimensionless).
ϕ = Ratio of specific gravity of the scrubbing liquid to that of water (dimensionless).
µ l = Viscosity of liquid (water = 0.8 cP = 0.0008 Pa-s; use Pa-s in this equation).

4. G ′ at operating is a fraction of G ′ at flooding:

G ′ operating = ƒ G ′ flooding (16.5)

5. Calculate the cross-sectional area ( A ):

Totalgas flow rate
Gasflowrateper u

Area = (16.6)

nitarea

or

A = G / G ′ operating (16.7)

6. The diameter of the tower is obtained from Equation 16.8:

d = (4 A /π) 0.5 (16.8)

The problem in Example 16.3 illustrates the calculation procedure for estimating the packed bed
tower chamber.

■ EXAMPLE 16.3. TOWER DIAMETER
Problem: For the scrubber in Example 16.2, determine the tower diameter if the operating liquid
rate is 1.5 times the minimum. The gas velocity should be no greater than 75% of the flooding veloc-
ity and the packing material is 2-in. ceramic Intalox™ saddles.

Solution : Calculate the value of the abscissa in Figure 16.8. From Example 16.2:

G m = 3538 g-mol/min
L m = 2448 kg/min

Convert gas molar flow to a mass flow, assuming the molecular weight of the gas is 29 kg/mole:

G = 3538 kg-mol/min × 29 kg/mol = 102.6 kg/min

Adjust the liquid flow to 1.5 times the minimum:

L = 1.5 × 2448 = 3672 kg/min

The densities of water and air at 20°C are

P l = 1000 kg/m 3
P g = 1.17 kg/m 3

Calculate the abscissa using Equation 16.3:

05 .

05 .

L
G

×

P
P

3672
102 6

117
1000

.

Abscissa = =

×

g
l

= 122 .

.