The rising film evaporator
was one of the first continous operation type evaporators that was used in the food
industry. This system uses a vertical tube bundle with steam condensing on its outside
surface. Liquid on the inside of the tube is brought to a boil with the vapor generated
forming a core in the center of the tube. As the fluid moves up the tube, more vapor
is formed resulting in a higher central core velocity that forces the remaining liquid
to the tube wall. Higher vapor velocities, in turn, result in thinner and more
rapidly moving liquid film. This provides higher heat transfer coeficients and
shorter product residence time.
The rising film evaporator has vastly improved product quality over previous types of
evaporators. In addition, higher heat transfer coeficients have resulted in reduced heat
transfer area requirements, thus resulting in a lower initial capital investment.
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