Investigating the influence of design parameters on the flow characteristics of a rectangular gas-solid fluidized bed with non-spherical particles

Fluidization with non-spherical particles finds extensive applications in various industries. Most studies focused on spherical particles, although the particles are hardly spherical in practice. Therefore, in the present study, experiments are performed in a laboratory-scale rectangular fluidized bed column of 0.8 m height and 0.15 × 0.035 m cross-section using Geldart D particles of non-spherical shape. This study primarily explores the influence of particle shape, various distributor orifice shapes, and plenum chamber height on pressure drop and solids holdup. It is observed that spherical particles require less pressure drop and have a higher minimum fluidization velocity compared to non-spherical particles. The flat round shaped non-spherical particles displayed a spouting behaviour and differs from the fluidization behaviour of other non-spherical and spherical particles. The square-shaped orifice distributor with sharp corners exhibit a higher minimum fluidization velocity due to the increased pressure drop across the distributor plate. For all the particles, the plenum with aspect ratio of 1.5 exhibited lower minimum fluidization than the plenum with aspect ratio of 1. In addition, the axial variation of solids holdup analysis revealed that the flat round shape particles are having larger fluctuations with all the three distributors. Finally, the pressure signals are analyzed in the frequency domain using the Fast Fourier Transform. The power spectral density analysis revealed the existence of single bubbles, multiple bubbles at a wide range of frequencies from 1 Hz to 5 Hz.