INCREASE OF THE COAL INJECTION RATE IN TH E BLAST-FURNACE THROUGH OPTIMIZATION OF THE INJECTION LANCES

The metrological investigations and the calculations performed have sh own that oxygen has to be added directly through the injection lances in order to optimize the combustion of coal in the tuyeres. Coaxial la nces are therefore used, which lead to a clearly improved reaction beh aviour in comparison with single or double lances without additional o xygen input. In this way it was possible to achieve at blast furnace N o. 1 in Schwelgern in October/November 1992 coal injection rates of up to 224 kg/t hot metal, at a coke consumption of 268 kg/t hot metal. C oaxial lances correspond basically to a parallel-flow burner, with the disadvantage of an incomplete mixing of the fuels and long burn-out p aths. The design of coaxial lances has therefore been optimized. In op timized coaxial lances the the impulse of the oxygen and/or pulverized coal is purposevully utilized, and thus the mixing of the fuels impro ved, the ignition time reduced, and the burn-out degree increased.