It is desired to recover ammonia from an air stream at 1 atm by absorption in water in a tower packed with 2-in. plastic Flexi-saddles operating at 30°C. The inlet gas contains 20 mol% ammonia and 99% of the ammonia is to be absorbed. Pure water is fed to the top of the tower at a rate 20% greater than the minimum rate. Find the height and diameter of a tower designed to operate at one-half of the flooding velocity needed to treat 1,360 kg/h of feed gas. Note that in this problem the mole fractions are definitely high enough that both equilibrium and operating lines are curved.