Numerical Simulation of Fluid Particle Flow Systems

Fluid particle flow systems, including fluidized beds, are an essential part of many chemical processes. The optimum design and scale-up of these systems require a thorough understanding of fluid particle flow patterns. Achievements of this understanding involve the development of experimentally verified multiphase flow equations and numerical simulation tools. This presentation provides recent contributions of the multiphase flow approach to fluid particle flow systems and fluidization. It features a review of the governing and constitutive equations, including the kinetic theory approach including extension of the kinetic theory for granular flow to the mixtures of multi-type particles assuming a non- Maxwellian velocity distribution and energy non-equipartition. In this study, each type of particle was considered as a separate phase with different velocity and granular temperature. The resulting momentum equation for each particulate phase includes phase interaction arising from collision pressure and particle-particle drag force. This model was applied to study simple shear granular flow of a binary mixture and flow of multi-type particles in the riser section of the circulating fluidized bed systems. To account for continuous variation in particle size and density distribution due to phenomena such as reaction, agglomeration, nucleation and growth at significantly less required computational time, a new approach to solve PBE (Population Balance Equations), FCMOM (Finite size domain Complete set of trial functions Method of Moments) is presented. In this study, the size distribution function is presented as a series expansion by a complete system of orthonormal functions, The FCMOM is implemented through an efficient algorithm and provides the solution of the PBE both in terms of the moments and in terms of the size distribution function. The FCMOM was validated with applications to particle growth, nucleation, particle aggregation, and linked with flow equations (CFD) to solve nonhomogeneous flow system in a riser, and crystallization processes.