Falling film evaporator

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A falling film evaporator is a device used industrially to concentrate solutions, especially solutions with heat sensitive components. The evaporator is a specialized heat exchanger; it consists of an outer shell which is filled with steam, and a number of vertical, parallel tubes through which the solution falls. The solution falls in a thin film. The pressure in the tubes may be lower than atmospheric pressure, in order to depress the solution's boiling point. A proportion of the water in the solution evaporates and is evacuated from the system; the concentrated solution is collected at the bottom of the evaporator.

Falling film evaporators are common in the manufacture of concentrated orange juice and condensed milk. They are attractive as a concentration process because of their energy efficiency and thermal gentleness.