2024-05-23 17:23:05
Basic requirements for refractory materials in coke ovens. The coke oven is the basic equipment of coking enterprises, which is a complex thermal kiln structure, divided into basic roof, small flue, heat storage chamber, inclined channel, combustion chamber, furnace, and other parts. The furnace age is generally between 30-35 years. The performance of refractory materials, the design of furnace structure, and the quality of furnace masonry are key factors determining the service life of coke ovens. During the operating cycle, most masonry structures are not easily repaired, therefore, refractory materials used for furnace construction need to be able to meet the requirements of coking production technology and be durable. Based on the characteristics of coking production, there are basic requirements for refractory materials used in furnace construction. Different parts of the coke oven body. The tasks undertaken, temperatures experienced, structural loads carried, mechanical damage suffered, and media erosion experienced vary, so the refractory materials used in each part should have different properties.
1. Refractory materials for combustion chamber (carbonization chamber) and inclined channel: The operation of the carbonization chamber is periodic. During normal production, the temperature of the vertical flue of the combustion chamber can reach 1300 degrees Celsius or above. The combustion chamber wall is the carrier of the heat required for coking, which requires that the furnace building material should have good high-temperature thermal conductivity. The combustion chamber partition wall also bears the structural load of the upper masonry and the gravity of the furnace top coal loading truck. This requires that the furnace building material should have the performance of not deforming under high-temperature loads. The carbonization chamber surface of the combustion chamber wall is also corroded by ash, slag, moisture, and acidic gases. Methane also infiltrates into the gaps of the brick body, producing carbon deposition. The bottom of the vertical flue Due to the slag erosion caused by coal dust and dirt, it is required that the furnace building materials should have high-temperature corrosion resistance. During coal loading, the carbonization surface temperature of the combustion chamber wall drops sharply from over 1000 degrees Celsius to 600-700 degrees Celsius, so it is required that the furnace building material should have resistance to high temperature fluctuations above 600 degrees Celsius. Due to the influence of coke pushing, it is also required that the bottom bricks of the carbonization chamber have high wear resistance. Therefore, the combustion chamber wall and the bottom of the carbonization chamber are constructed with silicon bricks.
The furnace heads at both ends of the carbonization chamber, due to sudden temperature changes when the furnace door is opened, have dropped from over 1000 degrees Celsius to below 500 degrees Celsius, exceeding the temperature limit for stable volume of silicon bricks (573 degrees Celsius). Therefore, materials with good thermal shock resistance should be selected for the furnace heads. Previously, the furnace heads of coke ovens below 6m were made of third class high alumina bricks, while the current 6m coke ovens use some red pillar stone bricks, while in 7.63m coke ovens, silicon wire stone bricks are used for masonry.
2. Refractory materials for the heat storage chamber: The upper and middle gun bodies of the heat storage chamber of large and medium-sized coke ovens are all built with silicon bricks, allowing the coke oven to expand uniformly as a whole. The temperature difference between the upper and lower layers of the grid bricks in the heat storage room is about 1000 degrees Celsius. The temperature difference between the rising and falling airflow is between 300-40 (TC), which requires the grid brick material to have high volume density and strong resistance to temperature fluctuations. Currently, 6m coke ovens tend to use low alumina clay bricks with less alkaline oxide impurities, while 7.63m coke ovens use clay bricks with Al2O3 content>40% from top to bottom, depending on the temperature used Clay bricks with an Al2O3 content of 30%~36% and semi silica bricks with SiO2>70%.
3. Refractory materials for small flue: When there is an upward airflow, the temperature of the small flue is lower than 100 degrees Celsius, and when there is a downward airflow, the temperature of the small flue is higher than 300 degrees Celsius. Therefore, it is required that the furnace building material should have resistance to temperature fluctuations below 300 degrees Celsius. Currently, silicon bricks are used for the single wall and main wall of the 6m coke oven, and clay bricks are used as lining bricks to resist periodic temperature changes. In the 7.63m coke oven, semi silicon bricks with good thermal shock stability are used.
4. Refractory materials are used for the furnace top and foundation top plate: After the carbonization chamber passes through the top, the furnace top area is formed. The furnace top structure is mainly separated by clay bricks, and the separated areas are filled with insulation materials. The surface of the furnace top is paved with dense, waterproof, and wear-resistant cylinder bricks. Below the small flue is the foundation top plate. The foundation top plate was originally built with four layers of red bricks, with a strength requirement of more than 10MPa. Now, according to the insulation requirements, it has been changed to high-strength lightweight insulation bricks, which are built in three layers.
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