A chemical plant is emitting an air steam containing 30 mol% Contaminant Q. You are asked to design a tray tower that will use pure water to reduce the Q levels to 3 mol%. The column is to operate at 1 atm and 20°C. The air flow rate is 200 kg air/h-m2 and the entering water rate is 8,000 kg/h-m2 ; these air and water flow rates are on a Q-free basis. Assume that water is non-volatile at these operating conditions and that the solubility of air in water at these conditions is negligible. The molecular weight of Q is 64 lb/lb-mol. a) For a 30% tray efficiency, determine the number of theoretical and actual stages required for this separation. b) One concern raised is that the temperature of the air stream could be much higher coming from the combustion plant. Discuss how this could impact your design estimate. c) What could be done with the exiting water stream containing the Q?

 

Solubility lb Q/100 lb HO 0.00 0.05 0.10 0.15 0.20 0.30 0.50 0.70 0.99 1.50 2.50 4.99 7.48 9.98 of Q in Water (20C) Partial Pressure of Q in Air (Torr) 0.0 1.2 3.2 5.8 8.5 14.1 26 39 59 92 161 337 518 697