A water-isopropanol mixture at its bubble point containing 10 mol% isopropanol is to be continuously rectified at atmospheric pressure to produce a distillate containing 67.5 mol% isopropanol. Ninety-eight percent of the isopropanol in the feed must be recovered. If a reflux ratio L/D of 1.5 times the minimum is used, how many theoretical stages will be required:

(a) If a partial reboiler is used?

(b) If no reboiler is used and saturated steam at 101 kPa is introduced below the bottom plate?

(c) How many stages are required at total reflux? Vapor-liquid equilibrium data in mole fraction of isopropanol at 101 kPa are

T, C 93.00 0.2195 0.4620 0.5242 0.5686 0.5926 0.6821 0.7421 0.9160 0.0118 0.0841 0.1978 03496 04525 0.6794 07693 0.9442 84.02 82.12 81.25 80.62 80.16 80.28 81.51