Basic requirements of refractory for coke oven

Coke oven is the basic equipment of coking enterprises, and it is a thermal kiln with complex structure, which is divided into foundation roof, small flue, regenerator, chute, combustion chamber, furnace and so on. Its furnace life is generally 30~35 years. The performance of refractory, the design of furnace structure and the quality m of furnace masonry are the key factors that determine the life of coke furnace. During the operation cycle, most masonry is not easy to be hot repaired. Therefore, refractory materials for furnace building must be able to meet the requirements of coking production process and be durable. Based on the characteristics of coking production, refractory materials for building furnaces have their own basic requirements. Different parts of coke oven body. The tasks, temperatures, structural loads, mechanical damage and medium erosion are different, so the refractories materials used in each part should have different properties.1. Refractory materials for combustion chamber (carbonization chamber) and chute
The work of the carbonization chamber is periodic. In normal production, the temperature of the vertical flue of the combustion chamber can be as high as 1300℃, and the combustion chamber wall is the carrier for transferring the heat needed for coking, which requires that the furnace building materials should have good high-temperature thermal conductivity, and the partition wall of the combustion chamber should also bear the structural load of the upper masonry and the gravity of the coal truck on the top of the furnace, which requires that the furnace building materials should have the performance of no deformation under high-temperature load. The carbonization chamber surface of the combustion chamber wall is eroded by ash, slag, moisture and acid gas, methane permeates into the gap of brick body to produce carbon deposition, and the bottom of vertical fire channel is eroded by coal dust and dirt, which requires that the furnace building materials should have high temperature corrosion resistance. When loading coal, the temperature of the chamber surface of the combustion chamber wall drops sharply from above 1000℃ to 600~700℃, so it is required that the furnace building materials should have the performance of resisting high temperature drastic changes above 600℃. Due to the influence of coke pushing, it is also required that the brick on the bottom of the chamber has high wear resistance, so the wall of the combustion chamber and the bottom of the chamber are built with silicon bricks.

The furnace heads at both ends of the carbonization chamber suddenly change in temperature when the oven door is opened, which drops from above 1000℃ to below 500℃, exceeding the temperature limit of stable volume of silica brick (573℃). Therefore, the furnace heads should be made of materials with good thermal shock resistance. The original coke oven heads below 6m are made of third-class high-alumina bricks, while the current 6m coke oven uses some andalusite bricks, while the 7.63m coke oven is made of hanging brick.

2. Refractory for regenerator

The middle and upper parts of the regenerator of large and medium-sized coke oven are all shot with silica bricks, which makes the whole coke oven expand evenly. The temperature difference between the upper and lower layers of checker bricks in the regenerator is about 1000℃. The temperature difference between ascending airflow and descending airflow is between 300~40(TC), which requires that the checker brick material should have the characteristics of high volume density and strong resistance to drastic changes in temperature. At present, 6m coke oven tends to use low-alumina clay bricks with less alkaline oxide impurities, and 7.63m coke oven uses clay bricks with Al2O3 content > 40%, clay bricks with Al2O3 content 30%~36% and semi-silica bricks with SiO2>70% from top to bottom.

3.Refractory for small flue

The temperature of small flue is lower than 100℃ in the presence of updraft and higher than 300℃ in the presence of downdraft. Therefore, it is required that the furnace building materials should have resistance to drastic changes in temperature below 300℃. Silicon bricks are used for the single wall and main wall of 6m coke oven, and clay bricks are used as lining bricks to resist periodic changes in temperature, while semi-silicon bricks with good thermal shock stability are used in 7.63m coke oven.

4. Refractory materials for furnace roof and foundation roof
After the carbonization chamber passes the roof, it is the roof area, and the roof structure is mainly separated by clay bricks. The separated area is filled with insulation materials. Top surface is paved with compact, waterproof and wear-resistant cylinder bricks. Below the small flue is the foundation roof. The foundation roof was originally built with four layers of red bricks, and the strength requirement is greater than 10MPa. Now, according to the insulation requirement, it is changed into high-strength lightweight insulation bricks, which are built in three layers.