Computational simulation of SE-SR of methane in a bench-scale circulating fluidised bed reactor: Insights into the effects of bed geometry design and catalyst-sorbent ratios

• CPFD model applied to full-loop simulation of bench-scale SE-SR of methane. • Explored SE-SR behaviour under conditions of low catalyst activity and low sorbent loadings. • Compared the performance of two reactor bed designs. • Low catalyst activity has relatively high impact on performance. Operating sorbent-enhanced steam reforming (SE-SR) of methane in fluidised bed reactors presents a promising pathway for industrial low-carbon hydrogen production. However, further understanding of its complex multi-phase behaviours under certain operating conditions is still needed to guide reactor design and scale-up. This study developed a computational particle fluid dynamic (CPFD) reactor model to study cyclic SE-SR performance. The model was used to simulate scenarios representing potential reductions in catalyst activity and sorbent inventory levels over time by varying catalyst-sorbent ratios. Additionally, the effects of two different bed geometry designs were examined. Results indicate that varying solids ratios influenced reaction progress, with optimised methane conversion and CO 2 capture observed at moderate ratios. Higher sorbent loadings enhanced thermal neutrality but risked increased calciner energy penalties. Bed geometry also influenced localised hydrodynamics. Detailed solids and gas concentration contours provided insight into segregation and spatial product distribution in the two designs.