A packed absorption tower is to be used to remove SO2 from a stack gas consisting of a mixture of SO2 and air. The flow rate and SO2 content of the gas mixture measured just before the packed tower are 25 m3/min and 5.0 percent by volume, respectively. The working pressure is 1 atm and the temperature of the packed tower is 25 C. Removal of 90 percent of the SO2 is required, and water, initially pure with respect to SO2, is to be used as the liquid solvent. The equilibrium line for SO2 and water can be estimated by y=30x. Determine the flow rate of water that represents 150 percent of the minimum liquid requirement, type and size of packing, pressure drop, column diameter, and height of packing. Guess the cost of the packed tower. By plotting, show briefly the possible auxiliary units of this SO2 removal unit.

(Hint: x and y are mole fractions of SO2 in liquid and gas phases, respectively and you can assume the overall gas phase mass transfer coefficient to be 2.0x10-4 kmol/s.m2.atm.)