Thermal Vapour Recompression Evaporators
Engineering and Manufacturing Evaporators for Chemical Process Industries
Thermal Vapour Recompression
To reduce energy consumption, a portion of vapour from an evaporator is compressed with high pressure steam in a thermocompressor so it can be condensed in the evaporator heat exchanger. The resultant pressure is intermediate to that of the motive steam and the water vapour. The remaining vapour is condensed in the next heat exchanger or condenser.
Only a portion of the vapor from an evaporator can be compressed in a thermocompressor with the remainder condensed in the next-effect heat exchanger or a condenser. A thermocompressor is normally used on a single-effect evaporator or on the first effect of a double- or triple-effect evaporator to reduce energy consumption. Like mechanical recompression, thermal recompression is more applicable to low boiling-point rise liquids and low to moderate differential temperatures in the heat exchanger to minimize the compression ratio.
The double-effect evaporator with thermal recompression requires 33% less steam than the conventional double effect. In essence, the steam usage for the double effect with thermal recompression is comparable to that of a triple-effect evaporator.