Vacuum rake dryer is a kind of intermittent dryer with conduction heating. As shown in the figure. The cylindrical shell is provided with a heating jacket, and a rake type agitator is installed on the horizontal shaft. Half of the rake blades are left and the other half is to the right.
The rotation speed of the shaft is 7-8r / min, and the shaft can be reversed and reversed every 5-8min. The dried materials fall from the top and middle of the shell. The materials are indirectly heated under the stirring of the continuously rotating rake teeth, and the light components are continuously vaporized and pumped away by the vacuum pump. Generally, it takes more than ten hours to dry the materials.
There are two types of this equipment: one is that both jacket and drive shaft are supplied with steam (or hot water); the other is that only jacket is supplied with heating medium.
It is suitable for drying materials that are not resistant to high temperature and easy to oxidize at high temperature, materials with explosion risk and materials that must be recycled. The material to be dried can be slurry, paste, granular, powder, or fibrous.
Main advantages: strong adaptability, wide application; good product quality; low steam consumption.
Disadvantages: long drying time and low yield.