An organic colloid solution in water is concentrated from 8% to 45% using a single-acting evaporator. The heating steam used has a gauge pressure of 130.8 kPa. There is an absolute pressure of 13.6 kPa inside the evaporator and the feed stream has a flow rate of 20000 kg/h. The total heat transfer coefficient is 2800 W/m2 ^oC. When the feed temperature is (a) 51.7 C, (b) 21.1 C and (c) 93.3 C, the mass flow rate (kg/h), steam economy and heat transmission area of the evaporator (m2) calculate. The specific heat of the feed solution is 3.77 J/g C.

The boiling point elevation of the solution is negligible. The latent heat of evaporation of water can be taken as the latent heat of evaporation of the solution.