The boiling point-equilibrium data for the system acetone-methanol at 760 atm mm Hg are given in Table 21.6. A column is desinged to separate a feed analyzing 25 mol % acetone and 75 mol % methanol into an overhead product containing 78 mol % acetone and a bottom product containing 1.0 mol percent acetone. The feed enters as an equilibrium mixture of 30 percent liquid and 70 percent vapor. A reflux ration equal to twice the minimum is used. An external reboiler is to be used. Bottom product is removed from the reboiler. The con condensate (reflux and overhead product) leaves the condenser at 25 C, the reflux enters the column at this temperature. The molal latent heat of both components are 7,700 g cal/g mol. The Murphree plate efficiency is 70 percent. Calculate the number of plates required above and below the feed.

Table 21.6:

Temp Liquid Vapor
64.5 0 0
63.6 0.05 0.102
62.5 0.1 0.186
60.2 0.2 0.322
58.65 0.3 0.428
57.55 0.4 0.513
56.7 0.5 0.586
56 0.6 0.656
55.3 0.7 0.725
55.05 0.8 0.8
56.1 1 1