When we use the rotary kiln in operation, there is a situation in which the preheating system is easily blocked. The reasons for this are as follows:

 

   1. The “internal circulation” between the rotary kiln preheater and the kiln is not smooth. When the temperature of the kiln exhaust gas reaches a certain value, the dust adheres to the wall of the exhaust gas pipe, and the dust is highly viscous due to adsorption of alkali, chlorine and sulfur. As the temperature rises, the amount and hardness of dust adhesion also increases, which forms a skin. The actual ventilation section of the pipeline should be reduced. Sometimes the sticky ash at the top of the cyclone is discharged into the cyclone cylinder, which blocks the lower part of the cyclone.

 

   2. The bottom of the rotary kiln preheater and the inside of the kiln are formed into an alkali ring. When the raw material and fuel in the preheater are high in sulfur and alkali, SO2 will be converted into SO3 when the temperature reaches 400-600 °C. SO3 is absorbed by the raw meal to form CaSO4, and CaSO4 melts at 860 ° C and easily forms an alkali ring with the powder at the bottom of the preheater and inside the kiln.

 

   3, the rotary kiln preheater is prone to crust. The deposits in the preheater and at the inlet of the rotary kiln contain higher alkali sulfate and alkali chloride, and the alkali sulfate contained in the kiln gas is separated by melt coagulation to form a substance combined with the combustion substance and the kiln dust. Such a melt forms a film on the raw material particles, which deteriorates the flow and causes clogging in the preheater.

 

   4, the operation: uneven feeding, fluctuations in raw material composition, improper flame formation, reducing atmosphere in the kiln, incomplete combustion, etc. easily lead to crust blockage of the preheating system.

 

   5. Rotary kiln equipment maintenance: kiln seal, manhole, cold damper and other air leakage, preheater lining erosion, flap valve too tight (inflexible), etc. are also likely to cause crust blockage in the preheating system.