Study of Rapid Combustion of Pulverized Coal using Oxygen Plasma.

为了延长焦炉的使用寿命和有效利用非炼焦煤，各炼钢企业都在逐年增加风口喷煤量。本文从利用氧等离子体获得煤粉最大燃烧的角度出发，讨论了氧等离子体利用过程中出现的一些问题以及大量喷煤对高炉的影响。在使用氧等离子体的情况下，最大的问题是电极的消耗率。然后，研究了电极消耗的机理。为了防止电极的快速消耗，一般在钨电极中加入钇、钍、氧化镧和氧化硒等高熔点氧化物。比较了两种电极的寿命，发现氧化钇在防止快速消耗方面表现出良好的效果。电极消耗的机理与氩工作气体中微量氧有关，甚至以ppm为数量级。高氧含量的影响将在本研究的下一步进行研究。在PCI操作的情况下，对高炉下部的影响很大。经PCI操作后，高炉下部形成细焦，气液透气性明显降低。本文采用一维高炉数学模型，对高PIC工况下高炉下部的情况进行了计算。PCI对煤中氢的影响最大，每增加200kg/HTM，PCI中氢的含量将提高到7%。在此基础上，建立了考虑氢、湿反应的数学模型，给出了高炉下部的温度分布和气体分布。

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.