Gas-Solid Turbulent Flow in a Circulating Fluidized Bed Riser; Numerical Study of Binary Particle Mixtures

摘要

A numerical simulation was performed on a turbulent gas-particle multi-phase flowudin a circulating fluidized bed riser based on a hard-sphere discrete particle model (DPM) for theudparticle phase and the Navier-Stokes equations for the gas phase. The sub-grid scale stressesud(SGS) were modeled with the SGS model proposed by Vreman (2004). The model enables theudcalculation of an arbitrary particle size distribution. In this work, binary mixtures of particlesudwith different diameters are used in the simulation. From the numerical results it is found thatudthe particles display a radial and axial diameter distribution. Small particles have a higherudvertical particle velocity than the large particles. With increasing superficial gas velocity, theudvertical particle velocity is increased. The average particle velocity and concentration vary bothudin the radial and axial directions. Finally, the numerical results are compared with theudexperimental and numerical results of Mathiesen et al (2000).