A distillation unit consists of a partial reboiler, a column with seven equilibrium plates, and a total condenser. The feed consists of a 50 mol% mixture of benzene in toluene. It is desired to produce a distillate containing 96 mol% benzene, when operating at 101 kPa.

(a) With saturated-liquid feed fed to the fifth plate from the top, calculate: (1) Minimum reflux ratio (LR/D)min, (2) The bottoms composition, using a reflux ratio (LR/D) of twice the minimum, and (3) Moles of product per 100 moles of feed.

(b) Repeat part (a) for a saturated-vapor feed fed to the fifth plate from the top.

(c) With saturated-vapor feed fed to the reboiler and a reflux ratio (L/V) of 0.9, calculate: (1) Bottoms composition, (2) Moles of product per 100 mole of feed. Equilibrium data are given in Exercise 7.13.