Drying and cooling is an important step in NPK fertilizer production process. The wet NPK fertilizer granules must remove excess moisture. The cylinder dryer dries the granules to a qualified state. The temperature of fertilizer delivered from the dryer is higher than normal temperature, which is prone to hygroscopicity reaction, and the treatment is completed by the cylinder cooler.
The diameter of the cylinder dryer produced by our factory is 800-2200mm and the length is 8-22m. The feeding end of the barrel is equipped with a sheet, which can move the wet material to the inside of the dryer, reduce the contact time between the material and the high temperature air flow, and reduce the phenomenon of material bonding to the inner wall. The middle part of the dryer barrel body is provided with a lifting plate, which can spread the material in the barrel body, make the material and the hot air exchange sufficiently, and make the moisture of the fertilizer evaporate. The rate of water evaporation of granular fertilizer is controlled by the diffusion rate of water from the center of granule to the surface. Because of the compactness of the particles and the slow diffusion of water, the materials should stay in the dryer for enough time and the particles should contact with the hot air evenly. The residence time of materials in the dryer is usually 15-30 minutes.
Dusty gas produced by cylinder dryer should be collected by cyclone dust collector and discharged after treatment to avoid environmental pollution. After the material is treated by cylinder dryer, the temperature is usually 70 - 90 ℃, and the material is then cooled into the cylinder cooler.