GEA supplies Bracco with falling film evaporator for the concentration of contrast media

How the GEA falling film evaporator works

The liquid to be concentrated is fed at the top of the heating pipes via a unique distribution system and runs down the inner walls as a thin film. Due to the external heating of the tubes, the liquid film begins to boil and partially evaporates. The downward movement initially generated by gravity is then increasingly supported by the thrust effect of the vapors, which are also flowing downwards. In the lower part of the evaporator and the downstream centrifugal separator, residual liquid and vapors are separated from each other. For the efficient functioning of the falling film evaporator it is critical that the entire heating surface, particularly in the lower area, is evenly and sufficiently wetted with liquid. If this is not the case, dry spots will form, leading to severe incrustation.

The selection of a suitable distribution device to enable the liquid to be concentrated in the head of the evaporator body is of great importance for complete coverage; coverage can be increased by extending the heating tubes, subdividing the evaporator several times or recirculating the product.

Falling film evaporators can be heated directly with steam or hot water and designed as single or multi-stage units. Heating with support from thermal and/or mechanical vapor compressors for heat recovery can deliver significant energy-savings.