EULERIAN-EULERIAN SIMULATIONS OF THE HYDRODYNAMICS OF A BINARY MIXTURE IN AN INTERNALLY CIRCULATING FLUIDIZED BED

ABSTRACT

The process of solid circulation in an internally circulating fluidized bed (ICFB) having two or more chambers can be developed by applying unequal gas velocities in these chambers. Such a process is beneficial to several applications and provides the means for the energy transfer between the chambers in the ICFB. In this paper, a multi-fluid CFD model incorporating the kinetic theory of granular flow is used to simulate the hydrodynamic characteristics of a binary mixture of particles in an ICFB using ANSYS-Fluent software. The mixture is composed of two particles of different sizes but the same densities. The ICFB has two chambers named the reaction chamber (RC) and the heat exchange chamber (HEC), separated by a vertical central baffle. An increase in the RC gas velocity U_R at constant HEC gas velocity U_H results in an increase in the circulation rate of the binary mixture. The circulation rate of small particles GB_s is found to be higher than that of the big particles GB_b. Increasing the slot size causes a decrease in the pressure difference between the chambers and consequently decreasing the solid circulation rate in the ICFB. The mixture circulation rate also decreases when the mixture is richer in GB_b particles than in GB_s.

Key words:
Simulations; Kinetic theory of granular flow; CFD; Solid circulation rate; Pressure difference