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Selection and Application of Refractory Light Burnt Magnesium Powder

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Selection and Application of Refractory Light Burnt Magnesium Powder

2021-03-03 15:03:00
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Rotary kiln-type incinerator, also known as rotary kiln, is a slightly inclined steel hollow cylinder lined with refractory bricks. Most of the waste materials are heated by the gas generated during the combustion process and the heat transferred from the kiln wall. The solid waste is sent from the front end to the kiln for incineration, and it is rotated to achieve the purpose of mixing the waste. It is necessary to maintain a proper inclination when rotating to facilitate the solid waste to slide down. In addition, the waste liquid and exhaust gas can be sent from the kiln head or the second combustion chamber, and even the whole barrel of waste can be sent to the rotary kiln incinerator for combustion. Rotary kiln incineration technology is currently the most mainstream technology in hazardous waste incineration technology. It is the most widely used furnace type. It is a highly adaptable multi-purpose incinerator that can incinerate a variety of solid, semi-solid, liquid, and gaseous wastes. Combustible wastes of various types and shapes (granules, powders, blocks and barrels) can be sent to the rotary kiln for incineration. Hazardous wastes are incinerated in rotary kilns, and generally go through several stages such as drying, pyrolysis, burning and burnout. After these stages, the harmful components in the hazardous waste are fully decomposed and destroyed under the action of high temperature, forming high-temperature flue gas and slag. These high-temperature flue gas and slag will cause corrosive damage to the refractory materials built in the rotary kiln.

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(1) High temperature resistance. It can operate in a high temperature environment above 800 ℃ for a long time. (2) High strength and excellent wear resistance. The refractory material in the light burned magnesia powder rotary kiln needs to have a certain mechanical strength to withstand the expansion stress at high temperature and the stress formed by the deformation of the rotary kiln shell. (3) Good chemical and thermal stability, to resist the corrosion of chemical substances in the flue gas, and to withstand the alternating thermal stress in the incineration state. (4) The thermal expansion stability is better. Although the thermal expansion coefficient of the rotary kiln shell is greater than the thermal expansion coefficient of the refractory material of the rotary kiln, the shell temperature is generally about 150-300 ℃, and the temperature of the refractory material is generally above 800 ℃, which may lead to the ratio of refractory materials. The thermal expansion of the rotary kiln shell is large, and it is easy to fall off. Due to the complex composition of the incineration waste, it has a strong corrosive effect on refractory materials. After a period of operation, the refractory materials of the rotary kiln are prone to cracking of the refractory bricks, loose brick joints, and asynchronous displacement and falling off between the rings. . Since the rotary kiln is the key equipment in the technical process of this project, the service life and shedding of the refractory materials of the rotary kiln are the main problems that directly affect the reliable and safe operation of the system.


The following specific measures are recommended: (1) Choose a refractory material supplier. The refractory material should be high-strength, high-temperature resistant, and acid-resistant compound type refractory castables or bricks that can prevent glass and other low-melting substances from sticking to the kiln. . For example, the thickness of refractory materials used in a hazardous waste incineration project is not less than 300mm; the chemical composition is chrome corundum bricks with Al2O3 not less than 80%; the apparent porosity is less than 20%; the use temperature is not less than 1700℃. (2) The size of refractory bricks shall be specially designed according to the characteristics of the hazardous waste provided by this project, and the overall dimensions shall be considered. (3) A dedicated refractory material positioning and anti-skid structure is installed inside the rotary kiln, so that the refractory material in the rotary kiln always maintains the expansion balance and the position of the refractory material in the entire rotary kiln under repeated start and stop or abnormal operation. Do not move to prevent abnormal sliding of the refractory material in the longitudinal and radial directions. (4) Adopting a unique advanced construction plan, changing the conventional staggered masonry rules of refractory bricks, adopting the same joint masonry, each circle is self-contained, and does not overlap with the front and rear circles, so as to ensure that the rotary kiln starts and stops. The refractory bricks are not twisted and broken during synchronous displacement, so that the newly made lining refractory bricks do not squeeze adjacent bricks when they are displaced in the front, back, left, and right. (5) Carry out the oven in strict accordance with the oven curve, implement strict management and monitoring of the actual oven curve, ensure that the actual oven curve meets the design requirements, and ensure that the oven passes the first acceptance to ensure the quality of the oven. (6) Control the thickness of the kiln skin attached to the surface of the refractory. Hazardous waste is sent to the rotary kiln through the feed structure for high-temperature incineration. After about 60 minutes of high-temperature incineration, the materials are completely incinerated into high-temperature flue gas and residue, and form a stable slag layer, commonly known as "kiln skin" for protection The role of refractory layer. The thickness of the kiln skin is controlled within 100mm, if it exceeds, it will cause uneven force on the kiln carcass. Through the above-mentioned five aspects of technical measures, the life of the refractory material of the rotary kiln is greatly extended, and the problem of the falling off of the refractory material of the rotary kiln has been effectively solved.


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