Systematic Analysis of Mixing and Segregation Patterns in Polydispersed Fluidised Beds for Combined Catalytic Applications

Fluidized beds are among the most promising technologies in renewable energy and chemical production, especially in bioenergy and biorefining systems, due to their excellent mixing features, good operating flexibility, and enhanced heat and mass transfer. In industrial operations, sizes and densities of the solid particles in a fluidised bed are various, and have significant influence on the fluidization process. The mixing or segregating behaviour of different classes of particles is essential for developing relevant chemical or physical processes and reactor designs, especially those where different catalysts or solid adsorbents are coexisting in the same reactor. However, limited research has been focused on the characterization of fluidization profiles of mixed particles in fluidized bed reactors, and at real operating conditions.

In this work, we investigate the expansion and segregations behaviours of mixed Geldart group powders (in binary or ternary systems), to mimic operation of polydispersed beds where different bed materials/catalysts are employed at the same time.

A novel X-ray imaging facility will be used to analyse and describe the real-time mixing and segregation profiles in a lab-scale reactor operated at different fluidization regimes and temperatures. The non-invasive X-ray technique can provide frame-by-frame imaging with extremely high time resolution, offering visual representation for the bed characterization within the reactor at different operating conditions. This study also aims to investigate the feasibility of combined catalytic applications in fluidised bed systems, such as twin beds and circulated fluidised bed systems. Knowledge generated in this study can help to design, improve, and optimise advanced thermochemical conversion technologies, especially those involving in-situ gas adsorption, such as sorption enhanced catalytic processes with catalyst cyclic regeneration, to overcome thermodynamic limitations of conventional processes, increasing efficiency and resilience.