An evaporator is to concentrate a 10% wt caustic soda solution to 50% wt. Feed enters at 100 o F. Steam is available and saturated at 50 psig and the evaporator can be operated at 9.96 psi vacuum....

An evaporator is to concentrate a 10% wt caustic soda solution to 50% wt. Feed enters at 100^oF. Steam is available and saturated at 50 psig and the evaporator can be operated at 9.96 psi vacuum. Overall heat transfer coefficient of the evaporator is 500 Btu/hr-ft2-^oF. The required production of the 50% wt NaOH is 10,000 lb/hr. Calculate the heating area and steam economy with
a. negligible boiling point elevation

b. boiling point elevation