CFD study of hydrogen co-injection through tuyere and shaft of an ironmaking blast furnace

Hydrogen (H-2) can be co-injected into the tuyere and shaft into a blast furnace (BF) for reducing CO2 emissions. However, the feasible co-injection schemes and their effects on in-furnace phenomena are not well understood. In this study, a multi-fluid industrial-scale BF model is further developed to investigate the impacts of H-2 co -injection through the shaft and/or tuyere on the BF internal state and overall performance in terms of tem-perature field, H-2 and CO utilisation efficiency, and species distributions. The results show that the proposed H-2 co-injection through tuyere and shaft allows H-2 to be better utilized and the overall BF temperature field can be improved, compared to respective tuyere or shaft injection cases. Further, the effects of high hydrogen injection rate at tuyere (i.e., low hydrogen injection rate at shaft) are studied. It is found that with increasing H-2 injection ratio at tuyere, the water gas reaction and water gas shift reaction are intensified; the temperature is decreased and the H-2 utilization efficiency is suppressed; the raceway adiabatic flame temperature (RAFT) gradually de-creases; the lowest coke rate is 285.8 kg-C/t-HM is found when the distribution ratio of injected H-2 is 4:6 at tuyere and shaft, and the highest coke replacement ratio is 4.1 kg-C/kg-H-2. Then, the possible operation stra-tegies for H-2-rich operation of blast furnaces are explored. This paper provides a cost-effective tool to understand the flow-thermal-chemical behaviours inside a BF when H2 co-injection schemes are employed.

Automated summary

In this study, a multi-fluid industrial-scale BF model is used to investigate the effects of hydrogen co-injection on the internal state and performance of a blast furnace. It is found that co-injecting hydrogen through the tuyere and shaft can improve the utilization efficiency of hydrogen and the overall temperature field of the furnace. The study also explores the possible strategies for hydrogen-rich operation of blast furnaces.