What is the erosion mechanism of refractory bricks in cement rotary kiln

The main function of rotary kiln refractory bricks is to protect the kiln body from the damage of high temperature gas and high temperature materials, so as to ensure the normal production. In industrial production, the service life of refractory bricks in the firing zone is very short, which often leads to unplanned kiln shutdown for maintenance, which is a key factor affecting the high quality, high yield, low consumption and annual operation rate of cement kilns.

Whether it is a wet-process kiln or a new type of dry-process rotary kiln, in the clinker calcination process, since the gas temperature in the kiln is much higher than the material temperature, the surface of the kiln lining is subjected to periodic thermal shocks every time the kiln rotates, and the temperature changes The temperature is 150-250℃, and thermal stress is generated in the range of 10-20mm surface layer of the kiln lining.

The kiln lining also withstands the alternating warp and axial mechanical stress of the brick masonry due to the rotation of the kiln, as well as the erosion wear of the calcined material. Due to the simultaneous production of silicate melt, it is easy to interact with the surface of the kiln lining refractory brick to form an initial layer in a high temperature environment, and at the same time infiltrate into the interior of the refractory brick along the pores of the refractory brick, and bond with the refractory brick to make the refractory brick. The chemical composition and phase composition of the brick surface within the range of 10-20mm change, which reduces the technical performance of the refractory brick.

When the sintering range of the material is narrow or the short-flame rapid sintering produces a local high temperature, the minimum temperature of the surface of the kiln skin will be higher than the liquid phase solidification temperature of the material, and the surface layer of the kiln skin will change from solid to liquid and fall off. After reaching the initial stage of the kiln skin, a new initial layer of the kiln skin is formed. When this situation occurs repeatedly, the kiln lining of the firing belt gradually becomes thinner from thick to thin, or even falls off completely, resulting in partial exposure of the kiln shell and red kiln. In fact, the kiln lining damage in the firing zone is officially like this. In the high temperature area, the thickness of the residual bricks is generally distributed in an arc with a large radius of curvature, and sometimes the arc bottom falls on the inner surface of the kiln cylinder.