Computational modeling of dense gas-particle flow in a pipe: kinetic theory approach of granular flow

Conservation of mass, momentum and fluctuation energy equations for solid and gas phases are used to compute the hydrodynamics of flow in a vertical riser. The two-phase flow model is derived from Boltzman equation for velocity distribution of particles. The model is generated from Navier-Stokes equation, except that the solid viscosity and stress are computed by simultaneously solving a fluctuating energy equation for the particulate phase. The turbulence of the gas phase is treated by SGS turbulence closure model. A no-slip boundary condition for the gas phase and a slip boundary condition for the particulate phase are used. The model predicts the core-annular flow structure in a riser, similar to that found experimentally in a dense gas-solid flow. The predicted time-averaged particle concentration, velocity and viscosity of particles are compared with the experimental data of Miller and Gidaspow and reasonable agreement is observed in a circulating fluidized bed. It is shown that the flow behavior is strongly affected by the plastic fluctuation energy and the momentum and energy transfer between the particulate and fluid constituents.