Service Life and Spalling Countermeasures of Refractory Materials Used in Rotary Kilns

2023-10-13 14:49:19

Industrial waste incineration rotary kilns are prone to temperature fluctuations during operation. Rotary kiln refractory materials must not only have good fire resistance and wear resistance but also have good thermal insulation properties and resistance to rapid cooling and heating. Moreover, due to the complex composition of incinerated waste, it has a strong corrosive effect on refractory materials.

Refractory Materials Used in Rotary Kilns

Due to these reasons, the refractory bricks of the rotary kiln are prone to cracking after running for some time. The cracks in the bricks loosen, causing different steps between the rings and falling off. The service life and spalling of rotary kiln refractory materials are key issues that directly endanger system reliability and safe operation. To address these issues, the following specific measures can be taken:

1. The refractory materials are effectively configured according to the internal combustion conditions and harsh environment of the rotary kiln. In the garbage input part of the incinerator, since the garbage input and sliding need contact materials, and the temperature of the input port changes frequently, the refractory material is required to have excellent wear resistance and thermal shock resistance. Wear-resistant castables or wear-resistant chrome corundum bricks can be used, when there is a large amount of molten salt and alkali in the incineration material, it is easy to penetrate the refractory material. If na2c high-density materials with low porosity should be used, electric fused refractory products can be used.

2. When applying the size of refractory bricks, the overall dimensions should be considered. The size should not be too large to prevent the bricks from falling off, falling off, or being damaged due to irregular cracking during use. The size should not be too small to prevent the brick joints from loosening due to different materials and multiple starts and stops during the operation of the rotary kiln. In architectural design, rotary kilns often use 300×200×150mm refractory bricks. The refractory insulation layer uses heat-resistant, corrosion-resistant, and wear-resistant composite high-alumina bricks. The refractory layer uses high-density heavy-weight high-aluminum refractory materials. The insulation layer uses Refractory materials and Lightweight high-aluminum refractory materials. The two materials are pressed together and then calcined at high temperatures. The linear transformation index is the same and is not easily damaged at high temperatures. The definition of brick joints should also be moderate. Brick joints are generally 2~3mm up and down.

3. The inside of the rotary kiln is equipped with an ordinary refractory sign anti-slip structure so that the refractory materials in the rotary kiln can maintain the best inflation balance and the fixed position of all refractory parts of the rotary kiln when the rotary kiln starts and stops continuously or operates abnormally. To avoid abnormal vertical and axial resistance of refractory materials.

4. Strictly carry out drying according to the drying line breakage, strictly supervise and monitor the specific drying line breakage, absolutely ensure that the specific drying line breakage meets the design requirements, and ensure that the drying passes the first inspection, thereby ensuring the drying quality.

5. The surface layer of refractory material is attached to the thickness of the kiln skin. Hazardous waste is sent to the rotary kiln for high-temperature combustion according to the feeding mechanism. After 60 minutes of high-temperature combustion, the materials are completely burned into high-temperature smoke and sediment, and a stable slag layer, also known as “kiln skin”, is produced, which can maintain the refractory layer. If the thickness of the kiln skin is controlled within 100mm, uneven stress on the kiln body will occur.

In addition to considering the heat resistance and corrosion resistance of the refractory materials, the layout of the rotary kiln should also consider the temperature resistance and corrosion resistance of the lining brackets, anchors, and steel shell plate materials, as well as the effective thickness of the furnace lining. Comprehensive and tight refractory materials should be used for lining to reduce gas channeling between brick joints. The thickness of other furnace walls should not be too large, and the temperature of the furnace wall should not be too low to prevent acid and alkali gases from condensing and corroding the furnace wall. The temperature of the furnace wall should not be too high. Too high a temperature will cause the steel shell to deform and endanger the safe use environment. The surface temperature of the rotary kiln is generally 180℃, with a fluctuation range of 150~350℃. The outer surface temperature of the rotary kiln can reflect the internal combustion conditions of the rotary kiln. During the specific operation on site, an infrared monitor should be equipped, and the operation team will detect and record the temperature area of the outer layer of the rotary kiln every 2 hours.

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