CFD Modeling of the Industrial-Scale Bottom-Fired Direct Reduced Iron Reforming Process

In the iron and steel-making process, direct reduced iron (DRI) is the very first step that uses CO and H₂ to reduce iron ore and therefore contributes to fewer CO₂ emissions than the conventional blast furnace process. The CO and H₂ required for the DRI process are generated from bottom-fired reformers with reformer tubes filled with catalyst particles and transported to the shaft furnace for iron-ore reduction. Therefore, the DRI reforming process plays an essential role in DRI production by supplying reducing gases of the desired composition, flow rate, and temperature. In the present work, a 3D computational fluid dynamics model is developed to simulate the industrial-scale DRI reforming process that includes the multicomponent gas mixture flow in reactor tubes and burners, heat transfer from burner to tubes due to combustion on the burner side, and reforming reactions in catalyst-filled tubes. The pressure drop on the tube side due to the presence of the catalyst is calculated through a porous media approach. Results show the formation of a long and narrow flame on the burner side due to combustion, which led to an increase in the temperature of the tube wall and at the tube center. This enabled endothermic reforming reactions on the tube side and resulted in the consumption of CH₄ and H₂O and the formation of CO and H₂. The model predictions of tube outlet reformed gas temperature and composition and the temperature at different axial locations at the tube wall and center are in satisfactory agreement with ArcelorMittal’s plant data.