An absorption tower was designed and built to remove 80% of a pollutant A from air fed into the bottom of the tower at a mole fraction of 0.01. The absorbing liquid is pure water and the liquid flow rate is 1.5 times the minimum possible. The equilibrium line is straight with a slope K = 1.0

(mol/mol).

(a) Make a graph of the equilibrium and operating lines. (b)

Determine the number of transfer units, , available in the column.

(c) Anew law is passed requiring that 90% of the A fed be removed instead of the 80% for which the column was originally designed. Assuming that the feed gas flow rate, inlet composition, and operating temperature and pressure remain the same, by how much should the liquid flow rate be changed? (d)

Another option for part

(c) is to keep the liquid flow rate the same but to increase the operating pressure. Assuming that the absorption process is controlled by the gas-side resistance and that  is approximatelyindependent of pressure, by how much should the operating pressure change? Note that K is a function of pressure.

N o.G