Study on liquid-solid fluidisation behaviour of coarse coal particles: Experiment and CFD simulation

Abstract

To improve the recovery rate of clean coal, a liquid–solid fluidised bed is typically used to process coarse coal slime of 0.25–1.5 mm. In this paper, a combination of experimental measurements and computational fluid dynamics (CFD) simulations was used. The fluidisation behaviour of four groups of coarse coal particles with different sizes and densities in a fluidised bed with rectangular cross-section was investigated.The Euler–Euler method, shear stress transport k–ω turbulence model, kinetic theory of granular flow (KTGF) and modified Gidaspow drag model were used for CFD simulations. The experiment and CFD simulation results showed that when JL/Umf was greater than 1, the expansion ratio of the fluidised bed of coarse coal particles varied as a power function of the JL/Umf value. The bed expansion ratio model developed by Tripathy et al. in a fluidised bed with a circular cross-section was also applicable to a fluidised bed with a rectangular cross-section. The pressure drop data at different heights indicated that the measured values showed a linear pattern with the measured height. This indicated that when JL/Umf was greater than 1, the coarse coal particles showed a uniform fluidisation characteristic. After choosing appropriate initial conditions and models, the CFD simulation agreed well with the experimental data. The experimental data and simulation results can deepen the understanding of liquid–solid fluidised beds of coarse coal particles, which is beneficial to improve the fluidisation quality of the fluidised bed and further improve the separation effect.