Hydrodynamic Study of Gas–Solid Internally Circulating Fluidized Bed Using Multiphase CFD Model

Abstract

Hydrodynamic study of gas and solid flow in an internally circulating fluidized bed (ICFB) is made in this study using the CFD multi-phase model. 2D and 3D computational meshes were used to represent physical ICFB geometries of 0.186 m and 0.3 m diameter columns. The model approach uses the two-fluid Eulerian model with kinetic theory of granular flow options to account particle-particle and particle-wall interactions. The model also uses the various drag laws to account the gas-solid phase interactions. The 2D simulation results by various drag laws show that the Arastoopour and Gibilaro drag models predict the fluidization dynamics in terms of flow patterns, void fractions and axial velocity fields in close agreement with the Ahuja et al (2008) experimental data. 3D simulations were also carried out for a large scale ICFB. The effect of superficial gas velocity and the presence of draft tube on solid hold-up distribution, solid circulation pattern, and gas bypassing dynamics for the 3D ICFB investigated extensively. The mechanism governing the solid circulation and the pressure losses in an ICFB has been explained based on gas and solid dynamics obtained from these simulations. Predicted total granular temperature distributions in 3D ICFB draft tube and the annular zone are qualitatively in agreement with the experimental data. The total Downloaded by [University of Colorado -Health Science Library] at 13:48 30 March 2015 2 granular temperature tends to increase with increasing solids concentrations and decrease with an increase of solids concentration.

Heat transfer effect in scaling-up a fluidized bed reactor for propylene polymerization

“…This characteristic of the radial prole of solid holdup was also found by published literature. 11,49 At low velocity, less bed expansion with high solid holdup was found, leading to less uniformity. On the other hand, at high velocity, high solid movement and bed expansion lead to low solid holdup and more uniformity.…”

Effect of Drag Models on the Numerical Simulations of Bubbling and Turbulent Fluidized Beds

“…The TFM (governing equations are provided in Tab. S2 of SI) coupled with the laminar and the k-e turbulence model is considered to run numerical simulations in bubbling and turbulent fluidized beds [11]. Interphase momentum transfer is modeled with seven different drag correlations, namely, Gidaspow [14], SO [36], Beetstra et al [17], Tenneti et al [18], EMMS [19], Gibilaro [37], and Brucato et al [38].…”

“…Since experiments can be cumbersome and expensive, the computational fluid dynamics (CFD) approach is already proved as a promising tool to predict the accurate flow dynamics in fluidized beds [7][8][9][10]. The Eulerian-Lagrangian [10] and two-fluid model (TFM) [7,[11][12][13] are widely adopted multiphase techniques for flow predictions in lab-scale fluidized beds (1-2 m) with Geldart B particles (40-500 mm, specific gravity 1.4-4). In the TFM, the solid and gas flows are statistically averaged and described as interpenetrating continua.…”

Construction of mathematical models of the statics of grain media considering the Reynolds effect

“…The difficulty of studying the behavior of granular materials is predetermined by their physical properties [2]. A granular material is a multi-phase environment, whose dispersed component is rather large solid particles, and the carrier environment is typically a gas (or a liquid) [3]. The effect of a carrier environment on dispersed particles is generally neglected [4].…”

“…2) liquid -the relative movements of particles can be significant, but have weak fluctuations of the field of velocities [11]. In this case, the behavior of the environment is significantly influenced by the presence of a carrier environment -a liquid (a gas) [3];…”