How Hydrogen Injection Impacts Reacting Flow in an Ironmaking Blast Furnace: An Industrial-scale CFD-DEM Study

Hydrogen injection (HI) is an emerging decarbonisation technology for ironmaking blast furnaces (BFs), yet its impact on the in-furnace phenomenon in the raceway of an industry BF remains unclear. In this study, an industrialscale Reactive Computational Fluid Dynamic Discrete Element Method coupling model (rCFD-DEM) is developed to study the impacts of HI on the raceway dynamics and coke combustion inside an industrial-scale BF. To overcome the limit in previous CFD-DEM works, this work considers the impact of top loading on the in-raceway reacting flow for the first time. The comparisons show that the raceway size is sensitive to the top loading ratio, suggesting that the top loading should be considered in future raceway modelling. Then, the quantitative effect of the HI rate is numerically evaluated. It is indicated that when the HI rate increases from zero to 8 kg/tHM, the raceway height and depth increase by 95% and 81%, respectively, under the investigated conditions. The underlying mechanism is explored: the increase in HI rate leads to an increase in inter-phase drag force and interparticle collision, and in the convection and radiation heat transfer rates by 33 and 32 times, respectively. This study provides a cost-effective tool to understand and optimise HI in industrial-scale BFs for a lower carbon footprint, empowering the steel industry with crucial insights.