Numerical analysis of hydrogen-based iron ore reduction in a fluidized bed reactor: influence of distributor plate on reaction kinetics

The development of hydrogen-based fluidized bed reactors is crucial for establishing a new steelmaking route that enables decarbonization of the steel industry. While diverse research efforts are underway to achieve commercial-scale systems, reactor design must account for system-level constraints arising from the inherent coupling among hydrodynamic, thermal, and chemical requirements. Reducing gas must fluidize the bed while supplying sufficient hydrogen and sensible heat. Understanding how key components of the reactor influence this coupling and reduction performance is therefore crucial for designing reliable reactors. Among them, the distributor plate is a critical component that governs gas distribution, gas–solid contact, and reaction uniformity. Therefore, the present study examined how the design of the distributor affects hydrogen-based iron ore reduction through a laboratory-scale fluidized bed. The gas–solid flow was modeled using an Eulerian–Eulerian multiphase approach combined with the kinetic theory of granular flow, and reduction was described by a three-layer unreacted shrinking core model. Local reaction rates near the distributor jets were about 2.1 times higher than without the distributor, yet the overall reduction differed by less than 1% due to rapid hydrogen consumption and strong particle mixing. These findings under the hydrogen-supply-limited condition are expected to differ under industrial-scale with high-pressure conditions. The developed CFD framework provides useful insight for the design and scale-up of hydrogen-based fluidized-bed reactors for sustainable, low-carbon steelmaking.