Numerical Simulation and Experimental Study of the Gas–Solid Flow Behavior Inside a Full-Loop Circulating Fluidized Bed: Evaluation of Different Drag Models

Abstract

Both experimental and computational studies of the fluidization of high-density polyethylene (HDPE) particles in a small-scale full-loop circulating fluidized bed (CFB) are conducted. Experimental measurements of pressure drop are taken at various locations along the bed. The solids circulation rate is measured with an advanced particle image velocimetry (PIV) technique. Bed height of the quasi-static region in the standpipe is also measured. Comparative numerical simulations are performed with a computational fluid dynamics solver utilizing a discrete element method (CFD-DEM). This paper examines the effect of different drag laws used in the CFD simulations through a detailed and direct comparison with experimental data from a small-scale, full-loop circulating fluidized bed. The Hill−Koch−Ladd drag correlation was shown to have good agreement with respect to system component pressure drop and inventory height in the standpipe.

Comparison of Riser-Simplified, Riser-Only, and Full-Loop Simulations for a Circulating Fluidized Bed

“…With the development of the model and computing capacity, more and more investigators conducted full-loop simulation of the CFB system [14][15][16][17][18][19][20][21][22], which treats the CFB as a whole dynamic system. Chu et al [14] conducted a 3D full-loop simulation for CFB by means of the combined continuum and discrete method.…”

Experimental and numerical investigation of sands and Geldart A biomass co‐fluidization

“…The Eulerian–Lagrangian framework in MFiX suite of solver has been used to model the fluidization of sand and biomass in this work. The gas phase is described by volume averaged Navier–Stokes equations and solved by semi‐implicit method for pressure linked equations method.…”

“…Due to the complexity of directly investigating biomass mixing with bed material under reacting conditions, mixing experiments under ambient room conditions are carried out. The gas pressure profiles are widely used to estimate the macroscale distributions of solids in fluidized beds . The electrical capacitance tomography sensors can provide an estimate of the mixing of biomass and sands based on the different permittivity of sand particles and biomass.…”

Elementary-Volume-Scale Simulations of Inertial Flow in Sphere Pack: Improvement of Di Felice Drag Model in High Porosity

“…Fluid-particle interaction forces are calculated using the fluid drag model, meaning that the motion of fluids and particles depends strongly on the drag model used. 8,9) The Ergun 10) and Di Felice 11) equations are often used to model drag forces in conventional CFD-DEM coupling simulations. The Ergun equation cannot be used in the high porosity range; hence, a combination of the Ergun and Wen-Yu 12) equations, the latter being a drag model for high porosity flows, has been used in the past studies.…”