CFD Study of Hydrogen Injection in Blast Furnaces: Tuyere Co-injection of Hydrogen and Coal

Hydrogen is a carbon-free clean energy and a potential fuel to mitigate CO2 emission in ironmaking blast furnaces (BFs) where the co-injection of hydrogen/coal is one of the most promising and feasible technologies. In this article, a 3D steady-state industrial-scale CFD model is improved and used for investigating the co-injection of hydrogen/coal in BFs. The model involves gas-particle-solid flow, heat and mass transfer related to the chemical reactions of hydrogen, coal and coke. This model has been validated against the measurements in terms of gas distribution, temperature and burnout. Several injection schemes of the co-injection of hydrogen/coal are designed under the conditions of constant bosh gas volume. The typical in-furnace phenomena, including the interaction between hydrogen and coal, are described, and the effects of the hydrogen injection rate on the co-injection of hydrogen/coal are analyzed. The simulation results indicate that hydrogen combustion enhances the devolatilization of coal, but hinders the volatiles combustion. It is found that, as the hydrogen rate increases, the raceway volume-averaged temperature increases and the raceway peak temperature increases and then decreases; both the raceway surface-averaged burnout and final burnout increase. Such different responses of them to hydrogen injection rates indicate the importance of 3D modeling study. In addition, the higher hydrogen injection rate increases the molar fraction of reducing gas components (H-2 and CO) in the coke bed. The model provides a cost-effective tool for the design, optimization and industrialization of the co-injection of hydrogen and coal.

Automated summary

This study improved a CFD model to investigate the co-injection of hydrogen/coal in ironmaking blast furnaces, showing that increasing hydrogen injection affects coal combustion characteristics. The model provides a tool for designing and optimizing the co-injection of hydrogen and coal.