A single-effect evaporator is used to concentrate 60000 kg h-1 of a 40 wt % NaOH solution which is fed to the evaporator at 40°C. The concentrated liquid is a 55 wt % NaOH solution. Saturated steam at 3 atm is available for heating. The vapour space in the evaporator is at a pressure of 10 kPa. The overall heat transfer coefficient is 2000 W m-2 K-1 Determine:
a) the amount of vapour produced.
b) the area required for the evaporator. Include clearly values of relevant properties. c) the economy.