Benzene and toluene are separated in a multi-stage distillation column. The feed flow rate is 100 mol s-1 and the distillate flow rate is 60 mol s-1. The reflux ratio is 2.6 and the recovery of benzene is 90%. The pressure can be assumed to be 1.5 atm throughout the column. The feed is 50% vapour and 50% liquid on a molar basis in equilibrium at 1.5 atm. The mole fraction of benzene in the liquid phase of the feed is 0.5.
i) By performing a total-mole balance and an enthalpy balance over the feed stage, show that the liquid and vapour flow rates below the feed are: Ls = Fq + Lr and VS=Vr+F(q-1), where q=(hv - hf)/(hv - hi) and the other symbols have their usual meanings.
The question belongs to Chemical Engineering and it discusses about calculation of liquid and vapour flow rates of the feeds with total mole balance and enthalpy balance.
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