Absorber-Stripper system as shown in Figure 1 was used to treat 50 mol/s waste airstream containing 7.4 mol % of benzene vapors from a chemical plant. In the first step, a non-volatile wash oil was used to absorb 90% of benzene vapors from the feed stream in the tray absorber. The wash oil entering the absorber contains 4.76 mol% of benzene. The flow rate of the wash oil used was two times of the minimum solvent flow rate. Then, the wash oil leaving the absorber was contacted with pure steam in the stripper. The oil leaving the stripper was returned to the absorber. In the stripper, a steam rate of 1.5 times the minimum gas flow rate was used. The equilibrium relationship for absorber is given as y = 0.136 x and for stripper is y = 1.77 x. By using Kremser equation, determine the number of tray for absorber and stripper required for this system. (25 Marks) Feed Gas Stripper Absorber Wash Oil Steam Figure 1: Absorber-stripper system for treating waste airstream