A coal gas is to be freed of benzene by scrubbing with wash oil as an adsorbent and the light oil recovered by stripping the resulting solution with steam. The circumstances are:

Absorber . Gas inlet is 0.5 m3/s at 107 kPa, 26oC, containing 2.0% by volume of benzene. A 95% removal of benzene is required. The wash oil enters the absorber at 26°C, containing 0.005 mole fraction benzene, and has an average molecular weight of 260. An oil circulation rate of 1.8 times the minimum is to be used. Wash oil-benzene solutions are ideal. The temperature will be constant at 26°C. The vapor pressure of benzene at 26°C is 100 mmHg (13.33 kPa). Compute the oil-circulation rate.

Stripper:

The solution from the absorber is to be heated to 120°C and will enter the stripper at 1 std atm pressure. Stripping steam (pure water) will be at standard atmospheric pressure, superheated to 122°C. The debenzolized oil, 0.005 mole fraction benzene, is to be cooled to 26°C and returned to the absorber. A steam rate of 1.2 times the minimum is to be used. Calculate the steam rate required. The temperature will be constant at 122°C.