PURPOSE: To prevent the adhesion of scale, maintain the efficiency of spray drying, and facilitate the maintanance of spray dryer by blasting cooling air onto the upside and downside of a rotary disk.
CONSTITUTION: When a slurry as an original liquid enters a rotary disk 3 through between a protective tube 7 and a rotary shaft 6, the slurry is injected in finely atomized state from an exhaust nozzle by means of a centrifugal force produced by rotation of the disk 3. On the other hand, high temperature gas flows into an inlet 2 and serves to dry the liquid droplets. During the drying process, cooling air is blasted onto the upside and downside of the rotary disk 3 from air blowing tubes 4 and 5. Thus, since no clogging of the slurry in the exhaust nozzle occurs, the slurry can be effectively sprayed, the efficiency of spray drying can be kept for a long period of time, and the maintenance of the spray dryer can be made easier.