A double effect backward-feed evaporator concentrates 10 000kg/h of Tomato juice from 2% to 50% solids. Dry saturated steam enters the evaporator of the first effect at 205 kPa while the second effect is operated at 13 kPa. The specific heat capacity is 4.18 kJ/kgk at all concentrations and that there is no boiling-point rise. The overall heat transfer coefficients are 1.1 and 3.0 kW/m² K respectively in the two effects, and the feed enters the second effect at 298K. (HINT: Since the feed enters as a cold stream, the first effect requires more heat than the second effect. AT₁ must be increased and AT2 must be decreased proportionately. In this case, assume AT₁ is increased by 2°C and AT2 is decreased by 2°C).

1. Draw the flowsheet for this process and define the applicable operating conditions for each effect.

2. Calculate the steam consumption required?

3. What is the area required in each effect, assumed identical, and the economy of the unit?

Answer rating: 100% (QA)

Solution steam product 50 Hv mv P Ist effect Solid mi H Given d... View the full answer