The Influence Of Production Operation On The Service Life Of Refractory Materials

The influence of production operation on refractory materials is complex. In the large pre-differentiation kiln, the following factors are the primary factors. 

(1) Firing temperature

The large pre-differentiation kiln is composed of preheater, differentiation furnace, efficient grate cooler, and windy road pulverized coal injection nozzle. The differentiation rate of the raw materials is up to 90%. The kiln and kiln hood are sealed and insulated. The temperature can be up to 1700 ℃, even 2000℃.the temperature of the transition zone, firing zone, cooling zone, kiln hood, the throat of the cooler, high temperature zone and injection nozzle is far higher than that in the traditional kiln. Even if high quality materials are used, the service life of the transition zone, firing zone and cooling zone is generally 0.5-1 year, even 3-5 months. The window and injection nozzle can only be used for 0.5-1 year, or even less. 

Therefore, during the trial production, the work-rate of the kiln is only 70%-75% per year. If the preheater and the differentiation furnace are not stable, the service life can be much shorter. So, it is necessary to measure the max firing temperature. 40% of the kiln damage cases are caused by the unproper max firing temperature. 

(2) Rotating speed

In the traditional rotary kilns, the rotating speed is 60-70 r•h-1. The rotating speed of most pre-differentiation kilns is up to 180-220 r•h-1. The linear velocity of rotary kilns can reach 1 m·s-1. In the new high-speed, large-diameter and high temperature dry kiln, the thermal stress, mechanical stress and chemical attack are more serious than that in the traditional kilns. This requries the kiln to have good stabilitiy and strength in the cold or hot state. The raw materials and the rotating speed should match with the firing conditions.