After the cement kiln is overhauled, the baking quality is very important. Because many manufacturers do not pay attention to this link, in the process of igniting and drying the kiln, the lining burst or even red kiln phenomenon occurs, which seriously restricts the service life of the kiln lining. Therefore, in the process of drying the kiln, the principle of “slow heating and no turning back” must be followed.
1、According to Hoobe’s law, the temperature differential stress on the lining is 6D=a·Δt·ED. At the operating temperature, the compressive elastic mold ED of the alkaline brick is 25N/mm², the thermal expansion rate a is 1.2%, and the △t is 1000℃, so 6D=0.012×1000×25=300N/mm², which is a direct-bonded magnesia-chrome brick. The structural strength is 6 times that of 50N/mm² and 10 times that of ordinary alkaline bricks, which are 30N/mm². If it is baked too quickly, the measures reserved in the kiln lining design to absorb this destructive force will not work, resulting in cracking and peeling of the alkaline bricks.
2、The brick lining is required to withstand the compressive stress caused by the elliptical force of the kiln body, the compressive stress caused by the temperature difference, and the compressive stress caused by the expansion of the product itself. Therefore, 1/3 of the structural strength of the lining is used to offset the temperature difference. compressive stress caused. Therefore, Δt can only be limited to <50°C. In this way, the temperature difference in the brick can be reduced, and the outward thermal expansion of the kiln body can offset part of the expansion force, so as to ensure the safety of the brick lining.
The following is the alkaline brick lining baking system for reference.
During the kiln lining baking, it is extremely important to rotate the kiln body from intermittent to continuous, and from low speed to normal speed, which can not only maintain the uniformity of the surface temperature of the kiln lining, but also avoid the deviation of the center line of the kiln body from the center and the increase of local ovality. Deformation of the kiln body.
Baking is the most critical link in the use of castables. Since the castable is relatively thick, dense, and difficult to discharge water, it is absolutely forbidden to heat up too fast during baking, otherwise it will cause the castable to crack.