Vacuum evaporator

thin-filmprocesslow temperature

Thin-film or thin-layer evaporators have been developed to purify temperatures sensitive products by evaporation. The temperature sensitive product can be both the high and the low boiling component in the mixture. The target was to operate at low evaporation temperatures means low vacuum and to minimize the residence time of the product in the evaporator. In order to reduce the evaporation temperature at the heated evaporation surface as far as possible the pressure incl. the hydrostatic pressure due to the liquid product itself should be minimized. The solution is a thin film of the liquid product on the inner side of a vertical evaporation pipe which is generated by a rotating wiper system. The rotating wiper equally distributes the down flowing liquid feed on the inner side of the wall. The film is about 0,1 to 0,5mm thick depending on the viscosity of the liquid, type of wiper system, rotating speed and liquid throughput. This thin film provides almost no hydrostatic pressure, minimum hold-up and almost no temperature and concentration gradient due to the good radial mixing performance. This provides highest evaporation rates means shortest residence time in the evaporator at lowest temperatures permitting the production of high quality temperature sensitive products. The vapors are mostly guided upwards in a counter current manner to a down coming condenser. De Dietrich Process Systems is able to provide you with a wide range of thin film evaporators made of Stainless Steel, Alloy, Borosilicate Glass or Glass-Lined Steel.