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What kind of refractory castable material is most suitable for coke oven door?

July 17, 2023

The coke oven door is frequently opened during production, the surface temperature is high, and the coke temperature changes greatly. Cordierite brick and clay brick are used in the lining of traditional coke oven door in China, but the service cycle is not long.


The reason is that the product is complex in the coking process of the coke oven door, and the chemical erosion of the product is serious, which diffuses into the interior of the brick through the apparent porosity of the brick, diffuses and destroys the lattice structure of the brick, reduces the performance of the brick, and reduces the service cycle. The temperature change of coke oven door is large, and the sudden heating and cooling lead to the surface crack of lining brick, and also cause the corner damage of refractory brick.


If the coke oven door uses refractory castable, the body density should not be too large. Because the large furnace door is too heavy, the thermal conductivity is high when it is opened frequently. However, the use of lightweight castable, low thermal conductivity, small thermal expansion coefficient and elastic modulus, good thermal shock resistance and other characteristics, but the strength is not good, the apparent porosity is large, can not meet the demand. If the cordierite material is used as castable, cordierite has high strength and strong acid gas erosion resistance, but the price is expensive, the masonry requirements are higher, and the replacement of local damage is more difficult.


In addition, during the use of the coke oven, the tar will firmly adhere to the lining surface, and the formed carbon layer will be thick, which will cause the furnace door to be closed loosely. If the carbon deposit is cleaned up, the mechanical force will accelerate the early damage of the furnace door lining bricks. In recent years, refractory castable blocks have been used in the door lining of large volume coke oven. The material is made of clay and fused quartz composite castable; Because of the combination of this composite property, the refractory castable has strong thermal shock stability, and can withstand the thermal shock and frequent opening of the furnace door in the process of coke oven production. Moreover, fused quartz has a strong ability to resist acid gas erosion and resist carbon formation.


The use of clay and fused quartz composite castable to make precast blocks, clay material is cheap, high strength, in the manufacture of molding module or the whole casting, the production process is simple, and the use is more convenient. The introduction of fused quartz with very low coefficient of thermal expansion into the clay has the double effect of reducing the coefficient of thermal expansion and toughening the micro-crack, and the thermal shock resistance will be increased. It is fully adapted to the temperature of frequently opening the furnace door under acidic high temperature. In addition, the volume density and thermal conductivity of fused quartz are low, the molten quartz is introduced into the clay material, the thermal conductivity of the castable is low, the weight of the furnace door is appropriate, and the performance of the coke oven door is fully met.


While the properties of composite refractory castable can be used, it can be made into prefabricated blocks, which is convenient for construction and has a long service cycle. Therefore, the use of clay and fused quartz composite refractory castable is most suitable for the use of coke oven doors.