Abstract
For prevention of scale in the multi-stage flash evaporator, bench scale tests were made by useing 6-stage flash evaporator, Each stage had a heat transfer surface of 1m2. The results were as follows:
1) A new method, in which equivalent amounts of CaCO3 and Mg (OH) 2 were added together with slaked lime, proved to be more effective on prevention of alkaline scale than any of the following three methods;“additive-treatment”,“addition of alkaline reagent” and “addition of seed mixture.” In the new method, the stable and high over-all heat transfer coefficient was obtained during the run of 314 hours.
2) The new method was applicable to either new or old multi-stage flash evaporator.
3) The experimental results from the addition of calcium sulfate anhydrate together with slaked lime showed that the new method was applicable to the range of deposition of calcium sulfate.
