Numerical investigation of coke oven gas (COG) injection into an ironmaking blast furnace (BF)

Blast furnace (BF) ironmaking is the predominating process for producing hot metal (HM). It consumes huge quantities of carbonaceous fuel materials and leads to massive CO2 emissions. The injection of coke oven gas (COG) into the BF is considered a promising solution. It recovers the COG that is a kind of off-gas in the steelwork, and reuses the COG as an H2-intensive fuel in the BF to partially replace the use of carbonaceous fuel materials. However, thus far, the technology is not widely adopted, mainly due to the lack of understanding regarding the effects of key operational parameters of COG injection on BF performance. In addition, the coupling effect of COG injection and BF operation particularly the control at furnace top is not clear, leading to the low utilization efficiency. In this work, a continuum-based BF process model is developed and validated to consider the injection of COG into a commercial scale BF through the tuyere. The model is validated by comparing the calculated key performance indicators with those measured in production. The impact of COG injection rate is studied and its coupling effects with top burden distribution have also been clarified. The simulation results show that an increased COG injection rate leads to improved BF performance, in terms of increased productivity and decreased consumption of carbonaceous fuel materials. However, the utilization efficiency of COG and the replacement ratio of carbonaceous fuel materials by COG is decreased. An optimum top burden distribution can be identified, which can improve the utilization efficiency of injected COG and achieve a relatively high replacement ratio. The findings from this work should be useful to guide production of BF with H2-intensive fuel injection, which helps to save the use of carbonaceous fuel materials and reduce CO2 emission.