The rotary vacuum dryer is a double cone-shaped rotary tank. In the vacuum state of the tank, steam or hot water is introduced into the jacket for heating. The heat is contacted with the wet material through the inner wall of the tank. The water vapor evaporated after the wet material absorbs heat is pumped out by the vacuum pump through the vacuum exhaust pipe. Rotary vacuum dryer is a new type of dryer integrating mixing and drying. The condenser, vacuum pump and dryer are matched to form a vacuum drying device. (if it is not necessary to recover the capacitor, the condenser can not be used.) this machine is advanced in design, simple in internal structure, easy to clean, and all materials can be discharged. It is easy to operate. It can reduce labor intensity and improve working environment. At the same time, because the material also rotates when the container rotates and there is no material on the wall, the heat transfer coefficient is high, the drying rate is large, the energy is saved, and the material is dried evenly and fully, with good quality. It is applicable to the concentration, mixing and drying of powder, granule and fiber in chemical, pharmaceutical, food and other industries, as well as the drying of materials (such as biochemical products) that need to be dried at low temperature. It is also applicable to the drying of materials that are easy to oxidize, volatile, heat sensitive, strongly irritating and toxic, and materials that are not allowed to destroy crystals.