Circulation evaporation

In circulation evaporators the solution to be evaporated circulates in each stage through one or several heaters. These are usually located outside the evaporator and are designed as tubular heat exchangers or plate heat exchangers. The circulation is effected either by the thermo syphon effect (natural circulation) or by an outside effect, i. e. circulation pumps or air circulation (forced circulation).

In order to reduce the steam cost, especially at large evaporation capacities, circulation evaporators are also designed multi-stage.