Numerical analysis-based evaluation of combustion and gasification characteristics of pulverized coal and coke in the raceway region

Steelmaking is essential to modern society but remains a major CO₂ emitter. To mitigate this, technologies like hydrogen-based steelmaking and alternative reducing agents are being explored. Injecting coke oven gas (COG) into blast furnaces offers a promising way to reduce CO₂ emissions and affects combustion behavior in the raceway. However, the impact of simultaneous COG and pulverized coal injection remains unclear due to complex in-furnace phenomena. This study develops a three-dimensional numerical model using the Eulerian-Lagrangian approach to simulate reacting two-phase flow in the raceway under varying COG injection rates. The model is validated against data from a tuyere combustion simulator, confirming its accuracy in capturing combustion and gasification of pulverized coal and coke. Simulations show that COG injection affects gas concentration, reaction zones, and temperature profiles. While COG promotes overall reaction rates, it alters oxygen distribution, influencing coal burnout. The study also reveals that the frequency of coal-coke collisions impacts coke consumption and coal's carbon conversion rate. Furthermore, it clarifies how COG modifies the proportions of gases reacting with coal and coke, offering insights for optimizing combustion in blast furnaces. • A 3D Eulerian-Lagrangian model was developed to simulate raceway combustion and gasification. • The model captured key raceway combustion and gasification trends, enabling quantitative analysis of COG effects. • COG injection increased the carbon conversion rate of pulverized coal via H₂O gasification. • Collision frequency between coal and coke significantly affected combustion dynamics. • COG injection changed spatial reaction zones and suppressed O₂ reactions.