Project ForgeMass Transfer
Mass Transfer Operations
GATE 2019
Hard
A countercurrent absorption tower removes 95% of A from a gas using pure solvent B. Inlet gas mole ratio Yin=0.02, carrier gas flow Gs=50 kmol/h, equilibrium Y=2X. Operating at twice the minimum solvent flow rate, the mole ratio of A in the exit liquid is (rounded off to three decimal places)
0.005(± 0.0005 accepted)
Explanation
Yout=0.05×0.02=0.001. At minimum L: X1,max=Yin/2=0.01. Ls,min=Gs(Yin−Yout)/X1,max=50×0.019/0.01=95 kmol/h. At Ls=2×95=190: X1=Gs(Yin−Yout)/Ls=50×0.019/190=0.005.
Source: GATE CH 2019 (2019)
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