| 摘要 |
PROBLEM TO BE SOLVED: To provide a blowing-off operation in blast furnace, which eliminates defective furnace condition or unstable phenomenon such as slipping, hanging, channeling, etc., developed just after restarting the blasting following blowing-off, and capable of smoothly executing, the start-up following the restart of the blasting in a short time, in a blast furnace executing pulverized fine coal blowing operation. SOLUTION: In this blowing-off method of the blast furnace for preventing the furnace condition deteriorating phenomenon at the time of restarting the blasting after blowing-off in the blast furnace executing the pulverized fine coal blowing operation, the pulverized fine coal blowing quantity from a tuyere is reduced over 5hr since the start of the blowing off. Further, coke quantity charged from the furnace top part is increased and controlled in the direction raising a heat flow ratio defined in the following equation at the time of starting the blowing-off. The heat flow ratio = (average sp. heat of charged materials into the blast furnace×average density×dropping speed)/(average sp. heat of gas in the blast furnace×gas density×gas flow speed).
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