Effect of Natural Gas Injection into Blast Furnace on Combustion Efficiency of Pulverized Coal

Reducing CO2 emission in ironmaking process is pressing issue. Low RAR (reducing agent rate) operation of the blast furnace and the utilization of hydrogenous reducing agent are effective to reduce CO2 emission. In this study, the influence of the hydrogenous reducing agent on the combustibility of the pulverized coal was examined by using a small scale combustion furnace. As a result, the combustibility of the pulverized coal was improved by simultaneous injection of the pulverized coal and the hydrogenous reducing agent. Furthermore, the fundamental study about the effect of natural gas (CH4) injection point on the combustibility of the pulverized coal was conducted by experiment using above mentioned small scale combustion furnace and by three-dimensional numerical analysis for further high efficiency. In the case of the relative position of CH4 injection point and the pulverized coal injection point being near, the ignition point of the pulverized coal came closer to lance tip. Especially, in the case of CH4 injection point being upstream in blow pipe about 0 to 20 mm from the pulverized coal injection point, the fastest ignition of the pulverized coal was confirmed by experimental and calculation results.