Simultaneously Overdeveloped Central and Peripheral Gas Flows of a Blast Furnace

The gas flow distribution in the radial direction of the blast furnace is of vital importance for its stable and economical operation. In this study, an experimental apparatus, simulating bell-less top charging, was built on a 1/15 scale of 5 800 m(3) blast furnace in Shasteel. Experimental results shows that the charging mode designed for the simultaneously overdeveloped central and peripheral gas flow leads to a thin coke slit in the intermediate part and a large center coke column in the model furnace. The intermediate coke slit is more thinner under higher U/U-mf, larger O/C and deeper stock line with the existence of coke collapse; and in the radial direction, the largest fluctuation of gas velocity exists at the center-adjacent point, the interface of center coke column and ore layer, where the small particle size coke gets fluidized, which coincides with the analysis of above-burden temperature fluctuation and observation from top camera during blast furnace operation. In combination with the actual online operation data, it is further revealed that the burden layer with locally-narrowed coke slit at the cohesive zone hinders the smooth gas flowing, resulting in a big fluctuation of gas flow at the bosh part and an unsmooth burden descending. Optimization of charging pattern was done in the cold model and applied to the 5 800 m(3) blast furnace. As a conclusion, optimization of coke charging mode to increase the intermediate thin part of coke layer is the most effective way to pursue the stable operation with high productivity.