Reboiler#Forced circulation reboilers

A forced circulation evaporator is an evaporator, which is generated by a circulation pump. He mostly takes place in the rectification application.

Principle

In contrast to a natural -circulation evaporator, a pump is used to force the liquid to be evaporated through the evaporator. The pump delivers the liquid in the lower part of the evaporator. Then passes along a heated surface, generally pipes, and begins to boil when the boiling point is reached. The vapor / liquid mixture is then returned to the bubble column, or where the two phases are separated. The liquid is then returned to the evaporator, wherein a part thereof can be discharged as residue or product.

Forced circulation evaporators can be built horizontally or vertically and are usually made ​​of tube bundles.

Scope

Forced-circulation evaporators are used when the use of a natural-circulation evaporator is not possible, for example, under pressures of about 300 mbar to about 50 mbar or weitsiedenden mixtures. Disadvantage compared to the natural circulation evaporator are the capital and operating costs ( power consumption) of the circulating pump must pump large quantities.

• Apparatus (process engineering )