Influence of production operation of rotary kiln on service life of refractory

      The influence mechanism of production operations on the service life of refractory bricks is complex and there are many factors. The analysis is mainly from the following two aspects.

      (1) The calcination temperature is too high to cause brick damage. The flame temperature in the new dry preheating decomposition kiln can reach more than 1700 ℃, and the working temperature of the transition zone, firing zone, cooling zone, kiln head cover, throat and high temperature zone of the cooler and the outer part of the nozzle are also far away. Higher than the temperature of the corresponding part of the traditional kiln. Even if high-quality refractory materials are used, the kiln lining life of the transition zone, firing zone and cooling zone of a large rotary kiln is generally 0.5-1 year, or even only 3-5 months; the life of the kiln mouth and nozzle lining is generally only 0.5 -1 year, or even shorter; kiln hood and cooler throat kiln lining life is about 2 years. In the trial production stage, the operation rate of the rotary kiln is generally only 70%-75% or even lower, and very few can reach 85%-90%. If the preheater and precalciner are in poor operating conditions, the decomposition degree of the materials entering the kiln is very unstable, which will cause the position of each process zone in the kiln to change frequently, which will inevitably lead to unstable kiln operation and faster damage to the kiln lining. For example, if the calcination temperature is too high, it will cause the refractory bricks in the kiln to damage the molten pit.

      (2) Brick damage caused by faster kiln speed. The speed of the new dry precalcining kiln often reaches 3-3.7r/min, even as high as 4r/min or more, and the linear speed of the rotary kiln cylinder reaches more than 1m/s. In the new dry process kiln with high speed, large diameter and high temperature, the comprehensive damage effect of thermal stress, mechanical stress and chemical erosion on the kiln lining is much greater than that of traditional kilns. This is the requirement that the lining of the new dry process kiln must have sufficient strength and stability no matter in the cold or hot state.