Study of Rapid Combustion of Pulverized Coal using Oxygen Plasma.

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The amount of PCI (pulverized coal injection) from Tuyere is increasing in each steelmaking company year after year, for the sake of the elongation of the life of coke oven and efficient utilization of the non-coking coal. In this study, in the view point of the utilization of oxygen plasma to obtain the maximum combustion of pulverized coal, some problems occurring from the utilization of oxygen plasma and the effect of large amount of coal injection on the blast furnace were discussed.In the case of the usage of oxygen plasma, the most large problem is the consumption rate of electrode. Then, the mechanism of electrode consumption was investigated.To prevent the rapid consumption of electrode, high melting point oxide such as Yttria, Thoria, Lanthanum oxide and selenium oxide were generally added to tungsten electrode. The lives of these electrodes were compared and Yttria showed good result to prevent the rapid consumption. The mechanism of electrode consumption is to related to the trace oxygen in the Ar working gas, even a ppm order.The effects of higher content of oxygen are investigating in the next step of this study.In the case of PCI operation, large influence on the low part of blast furnace will be significant. It was found that the fine coke was formed in the low part of blast furnace and the gas and liquid permeability decreased significantly by PCI operation. In this study, one dimensional mathematical model of blast furnace was applied to calculate the condition of the low part of blast furnace in high PIC operation. Most large effect of PCI would be the coal bearing hydrogen and the content of hydrogen will increase to 7% by 200kg/HTM,PCI.Then, reactions concerning to hydrogen and moisture were taken into account for the mathematical model and the temperature and gas distribution in the low part of blast furnace were shown.