Experimental Analysis and DEM-CFD Simulations of Non-Reacting Gas-Solid Flow in a MIDREX-Based Shaft Furnace

The MIDREX process is a standard technology for gas-based direct reduction of iron ore, accounting for over 60% of global production of Direct Reduced Iron (DRI). Its efficiency and product quality are governed by the interplay of gas-solid flow, heat transfer, and reduction kinetics inside the shaft furnace. This study combines experiments and coupled Discrete Element Method and Computational Fluid Dynamics (DEM-CFD) simulations to investigate gas-solid flow in a MIDREX-based shaft configuration. Experiments measure pressure drop, particle mass outflow, and local particle velocities under different operating conditions. The simulations reproduce particle mass outflow with very good agreement (2% deviation) and capture the main features of particle velocity distributions. Static pressure-drop predictions show average deviations of approximately 6% and 10% at gas flow rates of 400 and 1200 m3/h, respectively. Under dynamic conditions, the simulated particle descent velocity and the pressure drop agree closely with the experimental values, with a deviation of only 3.9% (descent velocity) and 7.8% (pressure drop).