Pollution Unlimited, Inc. has submitted plans for a packed ammonia scrubber on an air stream containing NH3. The operating and design data are given by Pollution Unlimited. We remember approving plans for a nearly identical scrubber for Pollution Unlimited in 1978. After consulting our old files, we find all the conditions were identical except for the gas flow rate. What is our recommendation (USEPA-84/09, p. 102)?
Given
Tower diameter = 3.57 ft
Packed height of column = 8 ft
Gas and liquid temperature = 75°F
Operating pressure = 1.0 atm
Ammonia-free liquid flow rate (inlet) = 1000 lb/ft2-h
Gas flow rate = 1575 acfm
Gas flow rate in the 1978 plan = 1121 acfm
Inlet NH3 gas composition = 2.0 mol%
Outlet NH3 gas composition = 0.1 mol%
Air density = 0.0743 lb/ft3
Molecular weight of air = 29
Henry’s law constant m = 0.972
Molecular weight of water = 18
Emission regulation = 0.1% NH3
Colburn chart