Thin Film Evaporation/Wiped Film Evaporators
——Design
Thin film evaporators are horizontal evaporator with wiper basket, gear motors and external condenser.
The vapour nozzle is typically arranged at the upper end of the evaporator in order to facilitate the transfer of the vapours to the external condenser.
Dea offers thin film evaporators from 0.058 to 3 m2 .
——Operation
Feed liquid is admitted into still under high vacuum, immediately spread into a very thin film and forced quickly down the evaporation surface. Heated walls and high vacuum drive the more volatile components (distillate) to the external condenser as the less volatile components (residue) continue down the cylinder. The resulting fractions, thus separated, exit through individual discharge outlets. Depending on application, the desired product is either the distillate or the residue fraction. Small amounts of condensable low MW compounds collect in cold trap upstream of vacuum system. For high solvent loads, an optional external condenser may be installed immediately downstream of the still.
——Particular features
Continuous distillation process.
Low operating pressures (100~10000Pa ,100Pa=1mbar).
Short residence time.
High evaporation rates.
Processing of high-boiling, high-viscosity or crystallizing products is possible.
Can be used as a reboiler for column.
Low fouling on evaporator wall.
——Fields of application
For separation of large quantities of components with high volatility.
For residue removal or decolorization.
For products with high-viscosity and easy to crystallizate.
For heat sensitive materials.