The powder spray dryer is a closed-circuit spray drying process for products made of ethanol, acetone, hexane, gas oil and other organic solvents, using inert gas (or nitrogen) as the drying medium. The product in the whole process is free of oxidation, the medium can be recovered, and the inert gas (or nitrogen) can be recycled. The closed-loop system designed for organic solvent recovery has extremely high requirements for explosion-proof control of the system, extremely high system automatic control performance, and strict GP requirements. Commonly used in spray drying of precision ceramics, pharmaceuticals, battery materials, and cemented carbide powder.
The powder spray dryer is also called a closed cycle spray drying system. Its characteristic is that the system forms a closed cycle loop, and the heat carrier can be recycled. For the drying of volatiles that are organic chemical solvents, or materials that can cause harm to people and the environment after escaping, the organic solvents or products contained in the material liquid are easily oxidized, flammable, and explosive materials. Under normal circumstances, it is necessary to use The materials in this process cannot contact gas, so most of the heat carriers use inert gases (such as nitrogen, carbon dioxide, etc.). The exhaust gas discharged from the dryer, after gas-solid separation, also passes through the condenser to recover the solvent or remove the moisture, and then enters the dryer for recycling after being heated up by the heater. This type of dryer needs to add refrigeration equipment in the system, the operating cost is high, and the air tightness of the equipment is required to be high. The powder spray dryer is mainly at normal pressure or slightly positive pressure to prevent air from entering the system.

The working principle of powder spray dryer:
The powder spray dryer works in a closed environment, and the drying medium is inert gas (or nitrogen). It is suitable for drying some materials with organic solvents or materials that are prone to hydrogenation during the drying process; the system uses inert gas as a The circulating gas has a protective effect on the dried materials. The circulating gas undergoes the process of carrying moisture and dehumidification, and the medium can be reused; the nitrogen is heated by the heater and then enters the drying tower. The powder material to be converted by the high-speed circulating atomizer is discharged from the bottom of the tower, and the evaporated organic solvent gas is under the pressure of the negative pressure of the fan, and the dust sandwiched in the gas is passed through the cyclone separator and the spray tower. The organic solvent gas is condensed into a liquid and discharged from the condenser, and the non-condensable gas medium is continuously heated and recycled in the system as a drying carrier.
The conventional ordinary powder spray drying machine achieves the purpose of dehumidification through continuous air supply and exhaust, which is also an obvious difference between the powder spray dryer and the ordinary centrifugal spray drying equipment: the inside of the drying system is a positive pressure operation to ensure With a certain positive pressure value, if the internal pressure drops, the pressure transmitter will automatically control the flow to ensure the system pressure balance.