Agitated Thin film dryer
The vertical/horizontal thin film dryer consists of a cylindrical, vertically/horizontally arranged body with heating jacket and a rotor inside. The rotor is equipped with rows of pendulum blades all over the length of the dryer. The hinged blades spread the wet feed product in a thin product layer over the heated wall and mix the product layer material intensively. Therefore, the volatile components evaporate continuously from the product layer with high evaporation rates. The hinged blades are designed with a minimum gap to prevent fouling of the heating surface by product but are never in contact with the heated wall.
The product enters the dryer at its top. The evaporation starts after heating to the boiling point. In the slurry zone first solids are formed and with advancing evaporation of the volatiles and continued shearing by the hinged blades the paste breaks up to powder. The final solid product is discharged by gravity at the bottom of the dryer via a suitable air lock.
Advantages of thin film dryers
- Continuous process
- Low evaporation temperatures within the product film
- Short residence time
- High evaporation rates possible
- Combination with a column to increase the number of stages is possible