| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for operating a blast furnace by which the discharge of unburned char from the furnace top is restrained and also, a large quantity of pulverized fine coal can be injected while holding the ventilation in the furnace good. SOLUTION: In the operation injecting a large quantity of pulverized fine coal, this operation is performed by setting the combustion ratio of the pulverized fine coal in a raceway into a prescribed range in the relation between the injecting ratio of the pulverized fine coal and an ash content in the pulverized fine coal, and thus, it is found that the discharge quantity of the unburned char from the furnace top is restrained to the minimum level, and the ventilation in the furnace can be held good. Then, this operation is performed by setting so that the combustion ratio of the pulverized fine coal in the raceway satisfies the following expression (1). 1-30/PCR(1-ωa)>=η>=1-60/PCR(1-ωa)...(1). Wherein,η: the combustion ratio (consumed ratio of the combustible element) of the pulverized fine coal in the raceway, PCR: the ratio of the injection of the pulverized fine coal (kg/per ton of molten iron) andωa: the ash content in the pulverized fine coal (weight ratio of the ash content to the pulverized fine coal quantity).
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