How to use high thermal conductivity silica brick as a new direction of refractory for coke oven？(1)
China is the world’s largest coke production and consumption country, and my country’s coke output accounts for about 60% of the world’s coke output. Coking process is also the most resource-consuming process in iron and steel enterprises, and its energy consumption accounts for about 13% of the energy consumption of the entire iron and steel process. In the new historical period, affected by the gradual deterioration of the environment, the coking industry is faced with a new challenge of raising energy conservation and emission reduction standards, and the task of energy conservation and emission reduction is important.
The refractory materials used in coke ovens are mainly China silica bricks, which account for about 70% of the total refractory materials. It is the most suitable refractory material for the currently known carbonization chamber furnace walls. In the coking process, at the same time and the same coal contact area, if more heat from the combustion chamber can be transferred to the carbonization chamber, it will play an energy-saving role. There are two general energy-saving methods: reducing the thickness of the furnace wall and improving the heat transfer efficiency of the furnace wall material. The furnace wall of the carbonization chamber is the weaker part, which plays a decisive role in the service life of the entire coke oven. Thinning the thickness of the furnace wall will inevitably reduce the strength of the structural unit of the furnace wall, which has a certain impact on the overall service life of the coke oven. At the same time, the furnace wall itself also has a heat storage effect. Therefore, improving the thermal conductivity of the furnace wall material plays a more important role in the balance of the overall structure and functionality of the furnace wall.
Traditional coke oven China silica bricks have good chemical stability. If the excellent performance of traditional coke oven China silica bricks can be maintained, and their thermal conductivity can be improved, the unity of the structure and stability of the material is guaranteed. Therefore, high thermal conductivity China silica brick is a product that conforms to the development requirements of coke ovens. Baosteel and related units have developed an ultra-high thermal conductivity furnace wall China silica brick, which has been successfully applied to Baosteel’s coke ovens.
Performance index of high thermal conductivity China silica brick
Compared with traditional China silica bricks, high thermal conductivity China silica bricks have been greatly improved in terms of structural morphology, crystal structure, and physical and chemical indicators. Structure and morphology of high thermal conductivity China silica bricks. After comparing the structure and morphology of high thermal conductivity China silica brick and traditional China silica brick by 20 times, it is found that the pore diameter of high thermal conductivity China silica brick is smaller and the distribution is more uniform. Gases within pores have lower thermal conductivity than solids, so pores always reduce the thermal conductivity of a material. In a certain temperature range, for a certain porosity, the smaller the pores, the stronger the thermal conductivity.
The tridymite content of high thermal conductivity China silica bricks is 70%, and that of traditional China silica bricks is 60%. The tridymite content of high thermal conductivity China silica bricks is 10% higher than that of traditional China silica bricks, and tridymite is a spearhead double crystal. The structure is very dense, which is conducive to the improvement of thermal conductivity. After the high thermal conductivity China silica brick improves the thermal conductivity, other performance indicators are consistent with the traditional coke oven China silica brick. That is to say, the high thermal conductivity China silica bricks all inherit the advantages of the traditional coke oven China silica bricks, and further highlight the high thermal conductivity characteristics on this basis. It can be seen that the performance of the high thermal conductivity China silica bricks is balanced in all aspects.
