Effects of using two- versus three-dimensional computational modeling of fluidized beds: Part II, budget analysis

The partial differential equations for modeling gas-solid flows using computational fluid dynamics are compared for different coordinate systems. The numerical results of 2D and 3D simulations for both cylindrical and rectangular domains are presented in Part I (N. Xie, F. Battaglia, S. Pannala, Effects of using two- versus three-dimensional computational modeling of fluidized beds: Part I, Hydrodynamics (2007-this volume), doi:10.1016/j.powtec.2007.07.005), comparing the hydrodynamic features of a fluidized bed. The individual terms of the governing equations in 2D and 3D simulations with the cylindrical and Cartesian coordinate systems are evaluated in this study through a budget analysis. The additional terms appearing in the 3D equations can be used to explain the discrepancies between 2D and 3D simulations. The values of the additional terms is shown to increase as inlet gas velocity increases. This explains the good agreement between 2D and 3D simulations that is observed for bubbling regimes with low gas velocity, and why the differences between 2D and 3D simulations increases for slugging and turbulent regimes.

[1]  Fariborz Taghipour,et al.  CFD Modeling of the Hydrodynamics and Reaction Kinetics of FCC Fluidized-Bed Reactors , 2005 .

[2]  Derek Geldart,et al.  The size and frequency of bubbles in two- and three-dimensional gas-fluidised beds , 1970 .

[3]  A. Kantzas,et al.  CFD Modeling and Validation of Bubble Properties for a Bubbling Fluidized Bed , 2005 .

[4]  J. Kuipers,et al.  Hydrodynamic modelling of dense gas-fluidised beds: comparison and validation of 3D discrete particle and continuum models , 2004 .

[5]  M. Syamlal,et al.  Fluid dynamic simulation of O3 decomposition in a bubbling fluidized bed , 2003 .

[6]  Ian Hulme,et al.  A Simulation and Experimental Study of the Hydrodynamics of a Bubbling Fluidized Bed of Linear Low Density Polyethylene Using Bubble Properties and Pressure Fluctuations , 2005 .

[7]  V. Swaaij,et al.  Hydrodynamic modeling of dense gas-fluidised beds using the kinetic theory of granular flow: effect of coefficient of restitution on bed dynamics , 2000 .

[8]  Rajamani Krishna,et al.  Validation of the Eulerian simulated dynamic behaviour of gas-solid fluidised beds , 1999 .

[9]  M. Syamlal,et al.  MFIX documentation theory guide , 1993 .

[10]  Francine Battaglia,et al.  Hydrodynamic modeling of particle rotation for segregation in bubbling gas-fluidized beds , 2006 .

[11]  Francine Battaglia,et al.  Effects of using two- versus three-dimensional computational modeling of fluidized beds: Part I, hydrodynamics , 2008 .

[12]  H. Enwald,et al.  Eulerian two-phase flow theory applied to fluidization , 1996 .

[13]  Bo G Leckner,et al.  Two- or three-dimensional simulations of turbulent gas–solid flows applied to fluidization , 2001 .

[14]  Ulrich Renz,et al.  Verification of Eulerian simulation of spontaneous bubble formation in a fluidized bed , 1998 .

[15]  C.R.E. de Oliveira,et al.  A numerical investigation of bubbling gas–solid fluidized bed dynamics in 2-D geometries , 2002 .

[16]  Britt Halvorsen,et al.  Numerical simulation of particulate flow by the Eulerian-Lagrangian and the Eulerian-Eulerian approach with application to a fluidized bed , 2005, Comput. Chem. Eng..

[17]  Todd Pugsley,et al.  Simulation and experimental validation of a freely bubbling bed of FCC catalyst , 2003 .

[18]  van den Cm Bleek,et al.  Eulerian simulations of bubbling behaviour in gas-solid fluidised beds , 1998 .