From the perspective of material drying,

rotary dryer is one of the indispensable drying machines. From the 60~70 years  0f the last century, the dryer was dried by furnace gas, to the steam heat exchange in 80s, and to the hot air conduction in 90s and the microwave and infrared drying. The principle and structure of the sand dryer have beencontinuously improved and improved.Because the current dryer equipment is used for conducting heating, not microwave and frared heating, the moisture  content of different drying results will be uneven, therefore, the cause of dry precipitation of the rotary dryer equipment is mainly due to the following aspects:

(1) the moisture content of the material is not equal.

(2) the hot air temperature of the dryer isunstable;

(3) the discharge is not uniform;

(4) less material is added to the dryer,

and the inside drum is not satisfied; (5) the wind pressure and air volume aresmall or high and low; (6) there are obstructions and dead angles in the tower.From the above analysis, it can be seenthat the dry precipitation uneven factors of the rotary dryer are not independent, but interrelated complex combination, the combination of differentfactors is different, one factor is unrealistic, and the ideal state is not existent. Each factor has different functions, but some of them can be overcome by others. Some are essential.