Computer simulation of the effect of center charging solid density or frictional property on the solid flow and deadman behavior in blast furnace

摘要

A center coke charging method from the top of blast furnace is known for a novel approach to burden distribution and coal combustion. This method is considered as one of the key technologies for keeping gas permeability of deadman in the lower part of blast furnace and producing iron liquid with a stable furnace operation. In recent years, the center charging method is also expected as improving the unsteady behavior with bridging/slipping of solid bed in low reducing agents operation of blast furnace. In the present study, a center charging method with different particle density or friction coefficients is carried out numerically by using a 3-dimensional Discrete Element Method (DEM). Before the numerical analysis, an experimental approach using a two-dimensional cold model is also examined. Alumina sphere was used as representative particle of coke/ore packed bed and the glass sphere was for the center charge. From the experiment, it was found that the height of deadman is reduced dramatically by using the center charging method with the glass sphere. This experimental result was compared with the numerical approach, although the gas flow was not considered in the numerical method. In the numerical results, the void fraction was calculated more precisely compared to the previous numerical two-dimensional calculation. Almost uniform particle flow distribution called a piston flow pattern was fairly maintained by the numerical center charging method, and as the result, the height of deadman was also confirmed reduced numerically compared to the alumina bed only. This result was qualitatively coincident with the experimental flow pattern except for the particle velocity descending faster in the experimental center-charging region, which could be available for the operation of deadman control.

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