A single effect evaporator is required to concentrate a NaOH solution from 20% solids to 40% solids at the rate of 250 k

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A single effect evaporator is required to concentrate a NaOH
solution from 20% solids to 40% solids at the rate of 250 kg of
feed per hour. The temperature of the feed coming in is boiling at
95°C. If the pressure in the evaporator is 120 kPa absolute, and if
steam is available at 200 kPa gauge, calculate the quantity of
steam required per hour and the area of heat transfer surface if
the overall heat transfer coefficient is 1700 W/m2
°C.
Do not assume the solution is the same as for
water.
Comment on the steam economy of this system.