Impact of particle size on the selection of a representative bed section for poly-dispersed fixed bed reactors

Journal of Fluid Flow, Heat and Mass Transfer

2023

Computational Fluid Dynamics (CFD) models are a valuable tool for the design, optimisation, and scaling-up of fixed bed chemical reactors utilised for carbon-neutral fuel synthesis, a crucial step for our timely transition to a sustainable economy/society. To enhance their accuracy, realistically representing the catalytic bed’s structure and 3D geometry is vital.

Researchers use computed tomography (CT) to non-destructively map internal structures of experimental fixed bed reactors, linking experiments and simulations. Previous research shed light on the highly poly-dispersed nature of fixed bed reactors formed by sieved particles with varying sizes, shapes, and orientations.

This study explores the selection of appropriate sample sections that accurately represent the bulk and radial porosity of the full bed. It identifies that due to the extreme heterogeneity of these beds, sample selection must be tailored to each case. Furthermore, it reveals that larger particles necessitate longer sections for accurate representation. A 10% section was selected, meshed, and its hydrodynamic profile examined to assess mesh independence. The results underscore the importance of choosing a suitable bed section and mesh size to reduce the computational demands, minimise the computational errors, and achieve the desired level of solution detail.