Numerical simulation of the hydrodynamics of a liquid solid circulating fluidized bed

•Numerical framework for a dense, liquid–solid flow in a complicated geometry•Three-dimensional effects of circulating fluidized beds resolved•Overall circulation achieved through natural initial and boundary conditions•Features of solid entrainment and liquid–solid separation captured in simulations•Qualitative agreement with reported experimental data

We present a modeling framework for the simulation of the hydrodynamic features of a liquid solid circulating fluidized bed (LSCFB) using computational fluid dynamics (CFD). Using an Eulerian–Eulerian approach to deal with the two-phase flow aspects and the kinetic theory of granular flow (KTGF) approach to deal with the solid–fluid interaction, we simulate the complete flow loop of an LSCFB using three-dimensional, time-dependent CFD calculations. We show that the essential features of the two-phase flow in the riser, the downcomer, the liquid–solid separator at the top and in the solids return feed pipe at the bottom are captured well in these simulations. The role of the flow distributors in establishing circulation is critically analyzed with the aid of post-processing tools. Comparison with literature data shows qualitative agreement with known trends of important hydrodynamic parameters and highlights the need for calibration of the constitutive equations for LSCFB applications.

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