Nowadays, reduction of amounts of CO2 from ironmaking process is important from the aspect of prevention of the global warming. COURSE50 is Japanese national project which aims to reduce the amount of CO2 emission from ironmaking process by 30% by 2050. In COURSE50, we try to reduce iron oxide with H2 to decrease amounts of carbon use, by injecting large amount of gas containing H2 and pulverized coal (PC) from tuyere. In that case, PC combustibility can be different from that in general blast furnace condition, due to high co-injected reducing gas ratio. Though a large number of researches about PC combustion around tuyere of blast furnace has been carried out, the effect of large amounts of co-injected reducing gas on PC combustibility was hardly investigated. To evaluate that, we conducted experiments with two experimental furnaces equipped with various non-contact measurement apparatus and found that;
1) The larger amounts of co-injected reducing gas were, the faster O2 and CO2 consumption, and CO and H2 generation in the raceway.
2) The amounts of co-injected reducing gas should be optimized for higher PC combustibility.
3) Co-injected reducing gas activated PC combustion by raising PC temperature, and that resulted in acceleration of PC.
4) Trade-off relationship between rapid heating effect and O2 consumption of co-injected reducing gas could determine the optimum amounts of reducing gas.
Consequently, we elucidated how we could co-inject reducing gas with PC as reducing agents without deteriorating PC combustibility.
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