An aqueous solution containing 10 mol% isopropanol is fed at its bubble point to the top of a continuous stripping column, operated at atmospheric pressure, to produce a vapor containing 40 mol% isopropanol. Two procedures are under consideration, both involving the same heat expenditure with V/F (moles of vapor generated/mole of feed) = 0.246 in each case. Scheme 1 uses a partial reboiler at the bottom of a plate-type stripping column, generating vapor by the use of steam condensing inside a closed coil. In Scheme 2, the reboiler is omitted and live steam is injected directly below the bottom plate. Determine the number of stages required in each case.

Equilibrium data for the system isopropanol-water are given in Exercise 7.33. The usual simplifying assumptions may be made.