An independent company wishes to hire a team of chemical engineers for the selection of an optimum procedure for the separation of benzene and toluene. A saturated-liquid mixture of 70 mol% benzene...

An independent company wishes to hire a team of chemical engineers for the selection of an optimum procedure for the separation of benzene and toluene. A saturated-liquid mixture of 70 mol% benzene and 30 mol% toluene, whose relative volatility is 2.5, is to be distilled at 1 atm to produce a distillate of 80 mol% benzene. Continuous distillation in a column containing one equilibrium plate. The feed is sent to the direct-heated still, from which residue is withdrawn continuously. The vapours from the plate enter the top of a helically coiled partial condenser that discharges into a trap. The liquid from the trap is returned to the plate, while the uncondensed vapour is condensed to form a distillate containing 80 mol% benzene. The molar ratio of reflux to
product is 0.5.

A. moles of distillate per 100 moles of feed,

B. moles of total vapour generated per mole of distillate, and

C. mol% benzene in the residue.

D. For each part, construct a y–x diagram. On this, indicate the compositions of the overhead product, the reflux, and the composition of the residue.