It is desired to design a continuous (shelf) distillation column operating at atmospheric pressure with a capacity of 15000 kg/h and separating a benzene-toluene mixture containing 35% benzene into a head product containing 90% benzene and a base product containing 95% toluene. The % given are percent by weight. 2.5 kg of reflux is used for each kg of head product. The mixture to be distilled and reflux enters the column as liquid at boiling temperature.

By applying the Ponchon-Savarit method: (use a millimetric paper, draw the graph)

a. Find the required theoretical number of stages and the location of the feeding stage.

b. Since the cooling water enters the condenser at 25C and leaves at 50C, find the required amount of cooling water. Cp(water): 1 kcal/(kg C).

c. Since the latent heat of saturated water vapor used in the heater is 513.7 kcal/kg, find the required amount of heater water vapor. The condensate leaves the heater as a saturated liquid.

Enthalpy-concentration values

x, y (weight fraction)	h (kcal/kg)	H (kcal/kg)
0	48	132
0.3	44	131.1
0.6	40	130.2
0.9	36	129.3
1	34.7	129

1 atm balance values

x	0	0.013	0.075	0.141	0.211	0.288	0.37	0.459	0.555	0.659	0.773	1
y	0	0.031	0.161	0.281	0.393	0.496	0.591	0.678	0.757	0.831	0.897	1