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How to choose refractory material in cement rotary kiln reasonably
Dec 12, 2018

These factors must be taken into account when selecting cement refractory lining refractories.

The rotary kiln system is the key equipment for cement production, and the refractory material is the key material for the lining of the rotary kiln. Therefore, care must be taken when selecting and configuring the refractory material. Unreasonable configuration will not only affect the normal production of cement, but also cause production accidents in severe cases.

The new dry process cement kiln system with kiln decomposition technology and suspension preheating has been widely promoted in cement production. Compared with the traditional rotary kiln, the new dry system is more complicated, and the kiln system is preheated. , decomposition furnace, kiln exhaust chamber, rotary kiln body, kiln door cover, burner, cooling machine, tertiary air duct, fan, humidification tower, electric dust collection and so on. Every part is vital, and problems in any one part can cause production to stop.

In dry cement kiln systems, wear of the lining material is the biggest problem, including thermal stress wear, chemical stress wear, and mechanical stress wear. Let's take the rotary kiln as an example to tell you what factors to consider when choosing refractory materials.

The first thing to know is the movement mode and condition of the material in the kiln. The cement raw material is calcined from the kiln at the end of the rotary kiln, the cylinder slowly tilts and rotates, the material moves in the circumferential direction, and finally enters the cooling system through the kiln door cover. In this process, the material exerts a huge frictional effect on the refractory lining in the rotary kiln. The composition of each thermal belt of the rotary kiln is the rear kiln mouth, the decomposition zone, the upper transition zone, the firing zone, the lower transition zone and the front kiln mouth. The maximum temperature in the kiln is 1800 °C, and the temperature of the kiln material is from 900 to 1400 °C.

The rear kiln mouth is connected to the preheater system, which is eroded by raw material scouring and high alkali sulfur content in the flue gas. The temperature of the flue gas in the decomposition zone is lower than 1300 ° C, but the body will be eroded by the high alkali content compound in the flue gas. The upper transition zone temperature is 1700 ° C. In addition to the influence of flue gas and fuel combustion, it is also subject to frequent changes in the elliptical stress and thermal stress of the cylinder. The firing zone is the highest temperature of the rotary kiln. The flame temperature can reach up to 2000 °C, the formation temperature of the material in the kiln reaches about 1400 °C, and it is also subject to the thermal chemical attack of the alkali sulfur compound. The lining of this part must have the ability to hang the kiln to protect the refractory brick layer.

After analyzing the erosion factors of various parts, the performance requirements of the refractory materials used will follow. The kiln mouth requires that the refractory material has good wear resistance, strong chemical erosion ability and high thermal shock stability. Characteristics: The refractory material requires refractory materials with good thermal shock resistance, corrosion resistance, high mechanical strength, and kiln skin; the transition zone requires high temperature thermal shock resistance and high mechanical strength; decomposition zone and pre-tropical zone The refractory material at the joint is less affected by chemical and stress corrosion, so clay or high-aluminum brick refractory products can be used, and the third-stage high-alumina, magnesia-chrome brick or spinel brick is used in the joint with the filter belt; The post kiln mouth needs an insulating and refractory product with good alkali resistance.

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