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Falling Film Evaporator

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Falling Film Evaporator
Falling film product distribution generally is based around use of a perforated plate positioned above the top tube bundle of the calandria. The main problem in this design is figuring how to design for the even distribution of liquid to each of the tubes. Once designed, spreading of liquid to each tube is oftentimes further enhanced by generating flash vapor at this point. The falling film evaporator does have the advantage that the film is 'going with gravity' instead of against it. This results in a thinner, faster moving film and gives rise to an even shorter product contact time and a further improvement in the value of heat transfer coeficient.

One advantage that falling film evaporators have over rising film evaporators is in efficiency. The rising film evaprator requires a driving film force, and requires a temperature difference of at least 25 degree F across the heating surface. In contrast, the falling film evaporator does not have a driving force limitation-permitting a greater number of evaporator effects to be used within the same overall operating limits. However, using the falling film technique, it is feasible to have 6 or more effects.

Evaporator product information is available in our equipment catalog.

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