- Time:Jul 17, 2022
Kiln skin is the cement clinker that adheres to the surface of the refractory material at high temperature (usually the firing zone) in the kiln
1. The role of kiln skin
The kiln skin plays a very important role in protecting the kiln lining and prolonging the service life of the refractory material. The flame operating temperature in today's large cement kilns is as high as 1700°C. If there is no kiln skin protection at all, the surface of the refractory material will work at very high temperatures, and the refractory material will easily suffer from high temperature and erosion. damaged. However, if there is a kiln with a thickness of 150mm in the rotary kiln, the hot surface temperature of the basic refractory brick can be reduced from 1500 ° C to 600 ~ 700 ° C, and the hot end expansion will be reduced from 1.5% to 0.6% ~ 0.7%. It can be seen that the formation and existence of the kiln skin can greatly ease the working load of the refractory lining, the erosion of the refractory material can be slowed down, and the life of the kiln lining can be extended.
2. How is the kiln skin formed
Since the kiln skin is cement clinker, what conditions are needed to form the kiln skin?
(1) The first condition is temperature, because the temperature in the kiln is high enough, the kiln material can form a liquid phase. When the kiln material is already in liquid phase and keeps rolling in the kiln body, the kiln material is buried in the kiln lining. After the kiln lining transfers heat to the kiln material and the temperature decreases, it can adhere to a part of the kiln material and freeze some of the fine-grained kiln material. " On the kiln lining, the kiln skin is initially formed.
(2) The second is to consolidate the kiln skin, which requires the cooperation of refractory materials. When the semi-molten kiln material meets the refractory bricks that start to "sweat", part of the clinker melt will penetrate into the bricks and react with the components in the bricks, making the adhesion foundation of the kiln skin more solid. In addition, the previously adhered kiln skin was "frozen" on the brick surface, and the kiln skin was hung up layer by layer until the dynamic equilibrium was reached, and the kiln skin stopped growing.
