Numerical Investigation of Wide Continuous Particle Size Distribution Effect on the Liquid-Solid Fluidized System

Liquid-solid fluidized beds with varying particle diameters encompass extensive application across hydrometallurgy, mineral separation, and biochemistry. In the present work, the numerical model based on the multiphase particle-in-cell method is developed to study the liquid-solid polydisperse fluidized bed system with continuous particle size distribution (PSD). After the proposed model is well validated with experimental data, the effects of PSD width on fluidization dynamics and particle behaviors are analyzed and discussed. The key findings can be summarized as follows. Following a full fluidization, noticeable layering emerges among particles, with larger particles primarily accumulating at the system bottom, necessitating higher slip velocity and particle Reynolds number (Re- p ) to remain suspended, thereby resulting in a reduced flow area and heightened solid holdup. A wider PSD width leads to a more even spread of particles across the diameters, enhancing the visibility of stratification. It also creates a more consistent distribution of solid holdup changes and pressure drops along the bed height. Moreover, it is found that particles around 1.09 mm in diameter, representing the average size, consistently gather at a dimensionless axial height of 0.1, irrespective of variations in PSD widths. Simultaneously, when considering this axial position as the boundary, there exists a contrary relationship between the variations in particle solid content, particle size distribution, fluid velocity, and bed pressure drop with the PSD width. Finally, decreasing particle size correlates with reduced slip velocity and Re-p , intensifying the particle susceptibility to fluid motion.