How are Evaporators Employed?
Water is sometimes pretreated by evaporation to produce relatively pure vapour which is then condensed and used for boiler feed purposes. Evaporators are of several different types, the simplest being a tank of water through which steam coils are passed to heat the water to the boiling point. Sometimes to increase the efficiency the vapour from the first tank is passed through coils in a second tank of water to produce additional heating and evaporation. Other types of evaporation include a 素lash type・which operates under a partial vacuum causing a lowering of the voiling point of water and evaporation at lower temperatures. Evaporators have advantages where steam as a sources of heat is readily available. They also have particular advantages over demineralization, for example, when the dissolved solids in the raw water are very high.
