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Simulations of Fluidized Beds with Geldart Group-A particles using the Multiphase Particle-In-Cell (MP-PIC) Method

Fluidized bed reactors are widely used in the chemical and petrochemical industries due to favorable gas-solid contacts and heat and mass transfer, and continuous powder handling capability. CFD modeling of fluidized beds has recently gained considerable attention. Reliable CFD models provide insights into highly dynamic gas-solid mixing process and hence guide the design and scale-up of fluidized bed reactors. In this presentation, we demonstrate the capability of an MP-PIC model [1] implemented in OpenFOAM Version 6 [2] for predicting the hydrodynamics of bubbling and turbulent fluidized beds for Geldart Group-A particles. The MP-PIC method is a Lagrangian-Eulerian model, where the gas is modeled as a continuous phase and solid particles are treated as discrete computational parcels, with a subgrid model to account for inter-particle stresses. Two pilot-scale reactor data sets [3,4], using fluid catalytic cracking (FCC) Geldart Group-A particles with Sauter mean diameter of 60 μm and density of 1489 kg/m3, were chosen to validate the MP-PIC model. Realistic boundary conditions and physical properties, including gas distributor geometries and particle size distribution, were incorporated into the model. The predicted bed density profiles, which characterizes macroscopic behaviors of fluidization are in reasonable agreement with the experimental data under a variety of superficial velocities, bed heights and particle fine contents. In addition to the model predictability, speed-up of parallelization for simulating a large number of parcels required for commercial-scale reactors was also studied.

References [1] Snider, D. M. "An incompressible three-dimensional multiphase particle-in-cell model for dense particle flows." Journal of Computational Physics 170.2 (2001): 523-549. [2] OpenFOAM official website (https://openfoam.org/). [3] Gao, Jinsen, et al. "CFD modeling and validation of the turbulent fluidized bed of FCC particles." AIChE Journal 55.7 (2009): 1680-1694. [4] NETL Challenge Problem III (2010): NETL’s Circulating Fluidized Bed (CFB) and PSRI’s Bubbling Fluidized Bed (BFB) (https://mfix.netl.doe.gov/experimentation/challenge-problems/challenge-problem-iii-2010/)