A single-effect evaporator is concentrating a feed of 9072 kg/h of a 10 wt % solution of NaOH in water at temperature of 288.8 K to a product of 50% solids. The pressure of the saturated steam used is 42 kPa (gage) and the pressure in the vapor space of the evaporator is 20 kPa (abs).

a)Neglecting boiling point raise and the heat of solution, calculate the steamused, the steam economy in kg vaporized/kg steam, required surface area ofthe evaporator.

b)Repeat the calculations taking into consideration boiling point raise and heatof solution