A multi-fluid computational fluid dynamics model was developed with wide size distributions in the riser of circulating fluidized beds. The flow model of particle phases is based on the kinetic theory of dense gases and the kinetic theory of granular flow with unequal granular temperatures between the particle classes. The interactions between particle-particle and gas-particles were considered in the model. Coupling between the particle phases was made through particle pressure

binary radial distribution function

viscosities

particle collision dissipation and conductivities. Turbulent flow of the gas phase was modeled by the large eddy simulation. The expression of radial distribution function of particles was proposed. Simulation results revealed a typical core-annulus flow structure with one gas phase and two solid phases in the riser.Radial and axial segregations of the mean diameter was predicted. The computational results agreed with the experimental data reported in the literature.