- Time:Jul 19, 2023
1. Formation of kiln coating
Kiln coating formation process 1: In the cement rotary kiln, the flame continuously heats the kiln lining and the surface of the material. With the operation of the kiln body, the material is constantly tumbling. When the material buries the lining body, the lining body will transfer the absorbed heat to the material, the temperature of the material increases, the temperature of the lining body decreases, and part of the material adheres to the kiln lining.
Kiln coating formation process 2: Over time, the surface of the refractory material begins to "sweat", that is, a liquid phase appears. That is, when the semi-molten kiln material is in contact with the refractory material, some of the fine particles stick to the refractory brick to form the kiln coating. If there are more "frozen" kiln materials and less "teared" and dropped kiln materials, the kiln coating will slowly thicken. As the thickness increases, the surface temperature of the kiln coating increases, and when the balance of "freezing" and "tearing" is reached, the kiln coating will no longer grow.
Kiln coating formation process 3: On the one hand, the clinker melt penetrates into the brick and reacts with the components in the brick; on the other hand, the adhesion continues, and the previously adhered kiln coating is "frozen" on the brick surface. Thus, the kiln coating is hung up layer by layer until a dynamic balance is achieved. If the temperature in the kiln or the composition of the kiln material changes sharply, the firing conditions change too quickly, the kiln coating will fall off frequently or the balance of "freezing" and "tearing" will be broken, and the kiln coating will fall off in a large area. However, as long as the firing conditions remain stable, the kiln coating will slowly form again.
2. The role of kiln coating
2.1. Extend the life of refractory materials: kiln coating is cement clinker that adheres to the surface of refractory materials in the high temperature zone in the kiln. It plays a very important role in protecting the kiln lining and prolonging the life of refractory materials. The flame temperature of the large-scale new dry process cement kiln is as high as 1700 °C or more. If there is no kiln coating protection, the refractory surface will work at a very high temperature. Refractory materials are quickly destroyed by the effects of heat and erosion.
2.2. Improve thermal efficiency: store heat energy, reduce the heat loss from the kiln shell to the surroundings, and improve the thermal efficiency of the kiln.
2.3. Protect refractory bricks: protect refractory bricks from direct exposure to high temperature and chemical erosion.
