In a wiped film evaporator or a thin film evaporator, a rotating wiper system distributes the crude product to a film on the inner surface of a heated pipe. The wiping system speeds up the evaporation process by keeping the product film turbulent so that the heat transfer and mass transfer are optimized.
The lower boiling fraction of the raw material evaporates within a short time out of the product film; the residence time of the product at the evaporator wall is very short. The vapours are condensed on an external condenser. The concentrate is continuously discharged out of the bottom part of the evaporator.
As the condenser is located outside of the evaporator and is connected to the evaporator via a pipe, the velocity of the vapours at high evaporation rates and low pressures will become very high. Because of the pressure drop created by the vapours on their way to the external condenser, the achievable vacuum in a wiped film evaporator is limited to about 1 mbar.
Advantages of wiped film distillation
Applications for wiped film evaporators
Wiped film evaporators manufactured by VTA
VTA provides wiped film evaporators from laboratory to production scale in sizes ranging from 0.04 - to 80 m² and for operating temperatures up to 400 °C. Different wiper systems are selected depending on the product properties.
The material for the product wetted evaporator parts will be selected depending on the corrosiveness and the reactivity of the processed products.
Product development in the VTA test centre
In the test centre VTA is able to perform feasibility and pilot tests with different sizes of wiped film evaporators. Production runs are also possible on the laboratory and pilot equipment.
Toll distillation at VTA site
In addition to the laboratory and pilot testing, VTA can perform toll distillation also on industrial scale wiped film distillation equipment.