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The life of the refractory lining, and the type of cooling system employed, in a blast furnace has a major influence on campaign life. By improving the method of cooling the lining life can be prolonged which leads to increases in campaign life and so a reduction of down-time for furnace repair, so improving productivity and, therefore, decreasing the unit cost of the hot metal. By S Sudhir, RR Kumar, RK Singh, VK Jha, BK Das and A Arora·
LINING life, cooling system and operating practice all have a major influence on the campaign life of a blast furnace. By improving the method of cooling, lining life can be prolonged, which will lead to an increase in the campaign life of the furnace. This facilitates a reduction of down-time of the furnace leading to a decrease in hot metal cost.
The improved process efficiency in blast furnace operations combined with ever larger furnaces has increased the heat flux with a consequent requirement for greater levels of cooling to ensure a long shelf life. The heat flux has a major influence on blast furnace operation, optimum heat flux being required for smooth furnace operation. Heat flux is thus used as a tool to set the burden distribution to optimise the use of the furnace gas.
The traditional function of the cooling elements and water cooling circuits is the protection of the shell. To achieve this goal the cooling system must remove sufficient heat from the refractory lining. The cooling water circuit must also keep the wall temperature of the cooling elements, plates or staves, within prescribed limits to optimise campaign life.
By recording the thermal status when the furnace is running in an optimum condition, heat loss may be minimised by optimising the quality of water, its thermal conductivity and that of its cooling materials. A small rise in water temperature is preferred which may be achieved by adjusting water flow and selecting materials of desired thermal conductivity. Any reduction of the heat load/loss will influence production costs.
Evolution of cooling
Blast furnace cooling systems have been developing since 1884. Until the late 1920s, cooling was applied to the hearth and bosh areas only. Cooling for the stack region was developed between 1930 and1940. External...