| 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 pulverized coal is used as a solid reducing agent and LNG is used as a flammable reducing agent, the lances are disposed so that an axial line extending from an end of the lance for injecting LNG and an axial line extending from an end of the lance for injecting pulverized coal cross each other. This causes main flows of LNG and pulverized coal injected from different lances to overlap. The LNG contacts O 2 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. |
