(Solved): A solvent-recovery plant consists of absorber and stripper plate columns. Ninety percent of the ...

A solvent-recovery plant consists of absorber and stripper plate columns. Ninety percent of the benzene (B) in the inlet gas stream, which contains $$0.06\mathrm{mol}\mathrm{B}/\mathrm{mol}\mathrm{B}$$-free gas, is recovered in the absorber. The oil entering the top of the absorber contains $$0.01\mathrm{mol}\mathrm{B}/\mathrm{mol}$$ pure oil. In the leaving liquid, $$\mathrm{X}=0.19\mathrm{mol}\mathrm{B}/\mathrm{mol}$$ pure oil. Operating temperature is $$77\mathrm{F}\left(25^{?}\mathrm{C}\right)$$. Superheated steam is used to strip benzene from the benzene rich oil at $$110^{?}\mathrm{C}$$. Concentrations of benzene in the oil $$=0.19$$ and $$0.01$$, in mole ratios, at inlet and outlet, respectively. Oil (pure)-to steam (benzene-free) flow rate ratio $$=2.0$$. Vapors are condensed, separated, and removed. Additional data are: $$\mathrm{MW}$$ oil $$=200,\mathrm{MW}$$ benzene $$=78$$, and $$\mathrm{MW}$$ gas $$=32$$. Benzene equilibrium data are: Calculate the: (a) molar ratio of B-free oil to B-free gas in the absorber; (b) theoretical plates for the absorber; and (c) minimum steam flow rate required to remove the benzene from $$1\mathrm{mol}$$ of oil under given terminal conditions, assuming an infinite-plates column.