Single-effect Evaporators: ConcepTest and Example Problem
Try to answer this ConcepTest and solve the example problem before using this module. Studies show that trying to answer the questions before studying material improves learning and retention. We suggest that you write down the reasons for your answers. By the end of this module, you should be able to answer these on your own. Answers will be given at the end of this module.
Example Problem 1
A 5.0 wt% sugar solution at 110ºC and 2.0 bar is feed to a single-effect evaporator that operates at 1.0-bar pressure. The evaporator is heated by saturated steam at 140ºC. The overall heat transfer coefficient is 2 kJ/(m2 s K) and the heat transfer area is 56 m2. What feed flow rate of sugar solution can be processed in order to concentrate the sugar to 8.0 wt%. What steam flow rate is needed if it all condenses to saturated liquid? What is the steam economy (kg water evaporated per kg of steam condensed)?