| 摘要 |
A method for operating a blast furnace that makes it possible to further increase combustion temperature and reduce a unit consumption of reducing agent is provided. When two or more lances for injecting reducing agents from a tuyere are used, and LNG is used as a flammable reducing agent and pulverized coal is used as a solid reducing agent, a position of an end of the lance for injecting LNG is situated closer to a near side in a injecting direction by more than 0 to 50 mm than a position of an end of the lance for injecting pulverized coal. By this, the LNG effectively raises the temperature of the pulverized coal. The LNG contacts oxygen and undergoes combustion earlier, so that explosive diffusion occurs and the temperature of the pulverized coal is drastically increased. This makes it possible to drastically increase the combustion temperature and, thus, to reduce the unit consumption of reducing agent. In addition, when a double wall lance is used as a lance for injecting pulverized coal, the pulverized coal is injected from the inner tube and oxygen is injected from the outer tube, so that it is possible to provide oxygen necessary to the combustion of the pulverized coal and to further increase combustibility. The outlet flow velocity at the lance is 20 to 120 m/sec to prevent deformation of the lance. |
