Work principle: Seal circulation spray drying system works in a seal circumstance. The drying gas is usually inert gas, such N2. It's applicable for drying material with organic solvent, toxic gas and the material easy to be oxidized. Adopt inert gas as circulation gas, so to protect the material to be dried. The inert gas circulates after dehumidification process. N2 is heated and then enters into drying tower. Liquid material is conveyed to centrifugal nozzle by screw pump, and then it's atomized into the liquid mist by the atomizer, the heat transferring process is finished in the drying tower. The dry product is discharged at the bottom of tower, the evaporated organic solvent is sucked by the vacuum generated by the fan. Power or solid material will be separated in the cyclone and sprinkling tower. The saturated organic gas is drained out after it's condensed in the condenser. The gas not condensed recycles in the system after it's heated continuously. Ordinary normal centrifugal spray drying process is realized by air conveying and exhausting process. This is the obvious difference between explosion proof type sealed circulation centrifugal spray dryer and ordinary centrifugal spray dryer. The drying media in drying system is N2, the interior is under positive pressure. To keep positive pressure stable, the pressure transmitter controls the inlet amount of N2 automatically.