2. (30 points) A packed bed tower is to be built to remove ammonia from a stream of N2 gas by absorbing the ammonia in pure, de-ionized water. The tower should be able to handle 1000 m of gas per hour with the gas containing a maximum of 5 vol% of ammonia. The process is happening at 25C and 1 atm. The ratio of gas to liquid flowrate is 1. You (as the design engineer) have the option of packing the tower with 2 Raschig rings or 2 Pall rings. Calculate (for both packing options) - Diameter of the tower if the gas velocity is half the flooding velocity. b. Pressure drop when the packed section is 20ft high. c. Which packing will you choose for your tower? Provide economic justifications for your choice. 1.0 0.8 0.6 0.4 1 I 0.2 L: 4500 0.2 - 1 -0006:7 1500 AP, inches water/ft packing 0.1 0.08 ------ Dry 0006:7-- 15 -4500 -Dry 0.06 g 0.041 11 2" Raschig rings 2" Pall rings 0.02 100 500 1000 2000 Air mass velocity, ibs./11?, hr