The furnace body of coke oven is mainly composed of combustion chamber, carbonization chamber, regenerator chamber and inclined flue, etc. It is a high temperature furnace for coking coal to be heated and decomposed, dry distillation and carbonization into coke under the condition of isolating air. The main refractory bricks are silicon brick, clay brick and high aluminum brick.

First, silicon brick

Silicon brick is an acid refractory material, with good acid erosion resistance, its thermal conductivity is good, the load softening temperature is high, generally above 1620℃, only 70~80℃ lower than its refractoriness. The thermal conductivity of silicon brick increases with the increase of working temperature, there is no residual shrinkage, and the volume of silicon brick increases with the increase of temperature in the oven process. Therefore, silicon bricks are ideal refractory products on coke ovens, and important parts of modern large and medium-sized coke ovens (such as combustion chambers, ramps and regenerators) are built with silicon bricks.

The key to determine the thermal stability of silicon brick is the density, and the density is one of the important symbols to determine the quartz conversion. The smaller the density of the silicon brick, the more complete the lime conversion, and the smaller the residual expansion generated during the oven process.

In the silicon brick, the density of the squame-quartz crystal is the smallest, the linear expansion rate is small, the thermal stability is good like quartz and quartz, the slag erosion resistance is strong, the thermal conductivity is good, the load softening temperature is high, and the volume is the most stable form of quartz. In the well-fired silicon brick, the content of squamite is the highest, accounting for 50%~80%; Cristobalite is second, accounting for only 10% to 30%; The content of quartz and glass phase fluctuates between 5% and 15%. When the working temperature is lower than 600~700℃, the volume of silicon brick changes greatly, the resistance to acute cooling and acute heat performance is poor, and the thermal stability is not good. If the coke oven works at this temperature for a long time, the masonry is easy to crack and damage.

Second, clay bricks

Clay bricks refer to clay products with Al2O3 content of 30% to 40% aluminum silicate material. Clay bricks are made of 50% soft clay and 50% hard clay clinker, according to certain particle size requirements, after forming, drying, and burning at a high temperature of 1300~1400℃.

Clay bricks belong to weakly acidic refractory products, which can resist the erosion of acid slag and acid gas, and the resistance to alkaline substances is slightly poor. Clay brick has good thermal performance and is resistant to acute heat and cold.

In the temperature range of 0~1000℃, the volume of clay brick expands evenly with the increase of temperature, and the linear expansion curve is approximately a straight line, and the linear expansion rate is 0.6%~0.7%, only about half of the silicon brick. When the temperature reaches 1200℃ and then continues to warm up, its volume will start to shrink from the maximum expansion. The residual shrinkage of clay bricks leads to the cracking of masonry joints, which is a major shortcoming of clay bricks. When the temperature exceeds 1200 ° C, the low melting point in the clay brick gradually melts, and the particles are very tight together due to the surface tension, resulting in volume contraction.

Due to the low load softening temperature of clay brick, shrinkage at high temperature, thermal conductivity is 15% to 20% smaller than silicon brick, mechanical strength is worse than silicon brick, so clay brick can only be used for secondary parts of coke oven, such as regenerator chamber wall, small flue lining brick and regenerator chamber lattice brick, furnace door lining brick, furnace top and rising pipe lining brick.

ThIird, high aluminum brick

High aluminum bricks are refractory products with Al2O3 content greater than 48% aluminum silicate or alumina, collectively referred to as high aluminum refractory products.

The refractoriness and load softening temperature of high aluminum bricks are higher than clay bricks, and the slag corrosion resistance (especially for acidic slag) is better, and these properties are improved with the increase of Al2O3 content, but the thermal stability is not as good as clay bricks. High alumina brick has high density, low porosity, high mechanical strength and wear resistance. Coke oven burner head and carbonizing chamber bottom brick