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Long-life configuration of blast furnace hearth structure and refractory material
Dec 26, 2018

The structure of the blast furnace hearth is similar to the structure of the hearth we described in the previous article. It is mainly divided into two types, namely, a composite hearth structure in which carbon bricks are combined with high-aluminum ceramic materials, and the type is a full carbon brick hearth structure. From the perspective of heat transfer, the combination of carbon brick and high-aluminum ceramic material is a combination of thermal insulation and thermal conduction, which is commonly referred to as a "insulation" furnace structure. The full carbon brick hearth structure is a complete thermal conduction mechanism, usually referred to as a "heat sinking" hearth structure.

Blast furnace hearth structure

As the name implies, the full carbon brick hearth structure is made of carbon brick in the hearth. This structure has been widely used in China. Relying on the high thermal conductivity of carbon bricks to reduce the hot surface temperature, forming slag, iron coke, graphite protective shell on the inner wall to protect the carbon brick lining <= Similarly, in the initial stage of the furnace, it will encounter similar problems with the whole carbon furnace bottom. When the cylinder wall slag, iron, coke, and graphite house protection shell cannot be formed relatively quickly, the carbon brick lining will inevitably be strongly eroded. If high-conducting carbon bricks are combined with strong cooling, the furnace wall niobium, iron, coke, and graphite are also promoted. The layered protective shell is formed quickly, and the function of the "insulated" hearth structure can also be realized.

In contrast, the combination of carbon bricks and high-aluminum ceramic materials (close to the cooling wall masonry carbon bricks, high-aluminum ceramic materials on the inner wall), in the early period of the opening of the furnace, high-aluminum ceramic materials The wall directly faces the slag iron to protect the carbon lining in the back; in addition, the low thermal conductivity of the high-aluminum ceramic material at the beginning of the furnace has a heat preservation effect on the hearth, which can increase the temperature of the molten iron by 18~25 ° C; Strong wear resistance, alkali resistance, and resistance to molten iron can greatly extend the life of the hearth during the dynamic period. However, due to the low thermal conductivity of the high-aluminum ceramic material, it is difficult to form a protective shell on its surface, which will be gradually eroded away. The function of the high-aluminum ceramic material fails in the furnace for 5 to 10 years, and the lining temperature and the hearth are generated. The fluctuation of heat load, the first wave of No. 1 blast furnace in Shougang used ceramic cups to have similar fluctuations in the production of 6-7 years, but after the long-term operation of the blast furnace, the furnace condition is relatively stable, and it is easy to reach when the hot surface contacts the carbon lining. Heat balance, slag, iron, coke, graphite layer protective shell can also be formed as soon as possible, into the steady state period of the blast furnace life, the carbon brick is subjected to shallow erosion, which effectively prolongs the life of the steady state period. The purpose of long life of the hearth.

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