A plant design calls for an absorber that is to recover 95 percent of the acetone in an air stream, using water as the absorbing liquid. The entering air contains 14 mole percent acetone. The absorber has cooling and operates at 80°F and I atm and is to produce a product containing 5.0 mole percent acetone. The water fed to the tower contains 0.02 mole percent acetone. The tower is to be designed to operate at 50 percent of the flooding velocity. 

(a) How many pounds per hour of water must be fed to the tower if the gas rate is 500 ft³/min, measured at 1 atm and 32°F?

(b) How many  transfer units are needed, based on the overall gas-phase driving force? 

(c) If the tower is packed with 1-in. Raschig rings, what should be the packed height?

For equilibrium, Assume that P_A = P_Aɣ_Ax, where In ɣ_A = 1.95(1-x)². The vapor pressure of acetone at 80°F is 0.33 atm.