A numerical study on the influence of nozzle arrangement on gas–solid flow kinetics in a hydrogen-based flash ironmaking reactor

Hydrogen-based flash ironmaking, which combines hydrogen reduction with flash smelting, enables the rapid reduction of iron ore powder in a suspended state and represents a new approach to low-carbon ironmaking. Existing research has largely focused on macroscopic reduction behaviour, with insufficient attention paid to the gas–solid two-phase flow characteristics and control mechanisms within the reaction tower; there is a lack of systematic understanding regarding the influence of nozzle configuration on particle dispersion and gas–solid contact efficiency. This study takes the hydrogen-based flash ironmaking reaction tower as its subject and employs the CFD-DEM method to systematically investigate the impact of five nozzle arrangement schemes on gas–solid flow characteristics. The results indicate that a double-layer, three-nozzle staggered arrangement increases the proportion of particles retained in the reaction zone by over 80 %, significantly prolonging residence time and enhancing gas–solid contact, thereby providing favourable flow conditions for efficient reduction. The study elucidates the regulatory mechanisms of gas–solid mixing governed by nozzle structure, providing a theoretical basis for reactor structural optimisation and process control.