The saturated liquid mixture at boiling point containing 42% A by mol is transferred to a distillation column at 500 mol/hr. being sent. The upper product contains 90% mol% A and the lower product 92% mol% B. The backflow rate is 1.5. A total condenser is used in the system.

Equilibrium data (mole fraction A):

x	0	0.20	0.40	0.50	0.70	0.80	0.90	1
y	0	0.51	0.715	0.795	0.91	0.945	0.98	1

Enthalpy data (cal/mol)

x or y	0	0.1	0.2	0.4	0.5	0.7	0.8	0.9	1
Hx (cal/mol)	3500	2900	2600	2100	2000	2000	2000	2000	2000
Hy (cal/mol)	9000	8900	8800	8400	8000	7100	6600	6000	5300

a) Find the ideal number of steps using the Ponchon-Savarit method. Feed rate is it at the level? (20P)

b) If the cooling water enters the condenser at 20 C and leaves at 70 C, the amount of cooling water used find it. (Cpwater 1 cal/g.C) (10P)

c) If saturated water vapor at 120 C is used as a heater in the boiler, the required water vapor in 1 hour Find the amount (Isb=505 cal/g). (10P)