| 摘要 |
<p>Provided is a method for operating a blast furnace in which further improvement in combustion temperature and further reduction of the specific consumption of reducing agents are possible. A double tube lance is used as a lance 4 through which reducing agents are injected into a blast furnace via a tuyere 3. By injecting a solid reducing agent such as pulverized coal 6 and an inflammable reducing agent such as an utility gas 9 through the double tube lance 4 and by setting the oxygen excess ratio of air blown to the tuyere 3 to be from 0.7 to 1.3, there is a significant increase in the temperature of the pulverized coal 6 due to the utility gas 9 which contacts O 2 contained in the blown air in first being burnt, which causes an increase in the heating rate of the pulverized coal 6 and the pulverized coal 6 being sufficiently burnt. As a result, there is a significant increase in combustion temperature, which makes it possible to reduce the specific consumption of reducing agents. At the same time, it is possible to prevent the double tube lance 4 from being deformed due to the increased temperature by setting the flow velocity at the exit of the outer tube of the double tube lance 4 to be from 20 m/sec to 120 m/sec.</p> |
