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416 Lawrence K.Wang et al.

To determine the required canister number (RCN), the C is divided by the amount of
req
carbon contained in a single canister and rounded up to the next whole number. Typically,
each canister contains 150 lb of carbon.
RCN = C /(150 lb carbon/canister)
req
RCN = ________

Example 8
2
Outline the step-by-step procedures for calculating the steam requirements (lb steam/min-ft ),
of a fixed-bed carbon adsorption system.
Solution
The step-by-step procedures for calculating the steam requirements of a fixed-bed regen-
erative carbon system are summarized as follows:

Step 1: Carbon Adsorber Efficiency
For a given HAP outlet concentration (HAP ), the adsorption time (θ ), the regeneration
e ad
time (θ ),and the steam requirement (St) can be determined using Table 3.
reg
θ =_______h
ad
θ =_______h
reg
St=________lb steam/lb carbon
Step 2: Steam Required for Regeneration

Calculate the steam requirement using
Q =NA [St(C' )/(θ −θ )]/60 (10)
s req req dry-cool
Q =_______ lb/h
s
Calculate Q /A :
s bed
A =Q' /U (10a)
bed e,a e
A =______ft 2
bed
Q /A =_________lb steam/min-ft 2
s bed
2
Typically, the Q /A is limited to 4 lb steam/min-ft to prevent fluidization of the carbon
s bed
bed. Assume Q = 0.25h, if no information is available.
dry-cool
Example 9
Determine the steam requirements of a fixed-bed regenerative carbon adsorption system
for air emission control.
The given data are as follows:
RE = 95%

HAP = 50 ppmv
o
St = 0.3 lb steam/ lb carbon (see Table 3)