We have a triple effect evaporator which has steam supply of 5kg/hr, the setup is a forward pass setup, feed enters the 1st setup at 10kg/hr of 50% concentration and leaves the final effect at 75% concentration. What is the product discharged from this setup?

Correct Answer: 6.67kg/hr
Applying mass balance, Total feed F = E + P3, where E = E1+E2+E3, P3 = XFF/XP = 0.5×10/0.75 = 6.67kg/hr.