In order to establish the coarse-sized pulverized coal injection technology in the blast furnace, the behavior of pulverized coal with the characteristic diameter of 350450μm has been investigated concerning the pyrolysis, combustion, gasification and accumulation, by use of two kinds of model experiment; one is the vertical tower type reactor called the combustion model and the other is the blast furnace type reactor called the hot model.
The coarse-sized coal is split and the small-sized coal is generated in the combustion model experiment. As a result, the combustion efficiency of coarse-sized coal is 10% lower than that of small-sized coal with the characteristic diameter of 50 μm.
As the coarse-sized unburnt char is gasified preferentially against coke in the lower part of the hot model, char is little accumulated in the model and little flown out of the top.
In the actual operation at Muroran No.2 blast furnace with 150 kg/t-pig injection of coarse-sized coal, the stable operation has been performed in which the permeability deterioration and deadman temperature drop are not occurred, and the unburnt char is little flown out of the furnace top.
