Page 446 - Air Pollution Control Engineering

10_chap_wang.qxd 05/05/2004 5:10 pm Page 418
418 Lawrence K.Wang et al.

The working capacity value, W , is usually 50% of the equilibrium capacity (W ). Using
c e
Eq. (1) and values from Table 1, the W is calculated as follows:
e
W = k (P ) m (1)
e partial
where
−6
P = (HAP ) (14.696 × 10 ) (2)
partial e
−6
−6
P = (HAP ) (14.696 × 10 ) = (700 ppmv) (14.696 × 10 ) = 0.01029 psia
partial e
Then, from Eq. (1), the equilibrium capacity is obtained.
W = k (P ) m (1)
e partial
From Table 1, k = 0.412 and m = 0.389.
Substituting these values into Eq.(1) yields the equilibrium capacity:
W = (0.412) (0.01029 psia) 0.389
e
W = 0.06945 lb acetone/lb carbon
e
Because the working capacity, W , is usually 50% of equilibrium capacity (W ),
c e
W = 0.50 W = 0.50 (0.069 lb acetone/lb carbon) = 0.0345 lb acetone/lb carbon
c e
The carbon requirement is calculated using
C = M θ /W (11)
req HAP ad c
C = (12.10 lb of acetone/h)(40 h)/(0.0345 lb acetone/lb carbon)
req
C = 14,029 lb of carbon
req
Typically, each canister contains 150 lb of carbon; therefore, the required canister number
(RCN) is calculated as follows:
RCN = (14,029 lb carbon)/(150 lb carbon/canister)
RCN = 93.5 canisters, therefore use 94 canisters

NOMENCLATURE
θ ad Adsorption cycle time (h)
θ dry-cool Bed drying and cooling time (h)
θ Regeneration cycle time (h)
req
2
A Bed area (ft )
bed
C Amount of carbon required (lb)
req
C' Amount of carbon required per vessel (lb)
req
3
D Density of HAP (lb/ ft )
HAP
D Vessel diameter (ft)
v
HAP HAP emission stream concentration (ppmv)
e
HAP HAP outlet stream concentration (ppmv)
o
k Isotherm empirical parameter
LEL Lower explosive limit (%)