Modelling of particle segregation in fluidized beds

Abstract

Mixing of different size and density particles plays a vital role in the hydrodynamics of fluidized beds. In this study, a multiphase model based on the kinetic theory of granular flow has been developed to study the mixing behaviour of biomass and sand particles in a bubbling fluidized bed. After validating the model using available experimental data from the literature, it was used to study the influence of various parameters such as superficial gas velocity, mixture composition and particle size. Emphasis was given on understanding the impact of these parameters on the particle segregation number, which is the parameter used to quantify the segregation behaviour of the fluidized bed. Results are plotted as the change in particle segregation number with respect to time for different mixture compositions, superficial gas velocities and particle diameters. The results show that mixing is promoted with the increase in gas velocities which give lower values of particle segregation number. Increase in ratio of biomass in the mixture leads towards segregation while increase in biomass particle diameter promotes mixing. The results of 2D simulations are also compared with the 3D configuration.