Cluster identification and characterization in the riser of a circulating fluidized bed from numerical simulation results

Abstract A methodology of identification and characterization of coherent structures mostly known as clusters is applied to hydrodynamic results of numerical simulation generated for the riser of a circulating fluidized bed. The numerical simulation is performed using the MICEFLOW code, which includes the two-fluids IIT’s hydrodynamic model B. The methodology for cluster characterization that is used is based in the determination of four characteristics, related to average life time, average volumetric fraction of solid, existing time fraction and frequency of occurrence. The identification of clusters is performed by applying a criterion related to the time average value of the volumetric solid fraction. A qualitative rather than quantitative analysis is performed mainly owing to the unavailability of operational data used in the considered experiments. Concerning qualitative analysis, the simulation results are in good agreement with literature. Some quantitative comparisons between predictions and experiment were also presented to emphasize the capability of the modeling procedure regarding the analysis of macroscopic scale coherent structures.

[1]  R. Jackson,et al.  The Dynamics of Fluidized Particles , 2000 .

[2]  Dimitri Gidaspow,et al.  Computation of flow patterns in circulating fluidized beds , 1990 .

[3]  Joachim Werther,et al.  Visualization of flow structures inside a circulating fluidized bed by means of laser sheet and image processing , 2001 .

[4]  Luben Cabezas Gómez,et al.  Numerical study on the influence of various physical parameters over the gas–solid two-phase flow in the 2D riser of a circulating fluidized bed , 2003 .

[5]  Liang-Shih Fan,et al.  Principles of gas-solid flows , 1998 .

[6]  Kemal Tuzla,et al.  Parametric effects of particle size and gas velocity on cluster characteristics in fast fluidized beds , 2000 .

[7]  D. Gidaspow,et al.  A bubbling fluidization model using kinetic theory of granular flow , 1990 .

[8]  Masayuki Horio,et al.  Three‐Dimension imaging of particle clusters in dilute gas—solid suspension flow , 1997 .

[9]  O. Molerus,et al.  Transient dynamics of solid concentration in downer fluidized bed , 1998 .

[10]  D. Drew.  Mathematical Modeling of Two-Phase Flow , 1983 .

[11]  L. Reh,et al.  On viscous momentum transfer by solids in gas–solids flow through risers , 2001 .

[12]  A. A. Amsden,et al.  A numerical fluid dynamics calculation method for all flow speeds , 1971 .

[13]  D. Gidaspow.  Multiphase Flow and Fluidization: Continuum and Kinetic Theory Descriptions , 1994 .

[14]  S. Mutsers,et al.  The effect of interparticle forces on the expansion of a homogeneous gas-fluidized bed , 1977 .

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

[16]  Lounes Tadrist,et al.  Computational study of fluctuating motions and cluster structures in gas–particle flows , 2002 .

[17]  Tron Solberg,et al.  Predictions of gas/particle flow with an Eulerian model including a realistic particle size distribution , 2000 .

[18]  D. Gidaspow,et al.  Hydrodynamics of binary fluidization in a riser : CFD simulation using two granular temperatures , 2003 .

[19]  Collisional solid’s pressure impact on numerical results from a traditional two-fluid model , 2005 .

[20]  S. Ergun.  Fluid flow through packed columns , 1952 .

[21]  D. Zhang,et al.  High-resolution three-dimensional numerical simulation of a circulating fluidized bed , 2001 .

[22]  J. Kuipers,et al.  Granular dynamics simulation of cluster formation in dense riser flow , 1998 .

[23]  F. E. Milioli,et al.  Gas-solid two-phase flow in the riser of circulating fluidized beds: mathematical modelling and numerical simulation , 2001 .

[24]  Jinghai Li,et al.  Discrete simulations of heterogeneous structure and dynamic behavior in gas-solid fluidization , 1999 .

[25]  F. E. Milioli,et al.  A numerical simulation analysis of the effect of the interface drag function on cluster evolution in a CFB riser gas-solid flow , 2004 .

[26]  A. A. Amsden,et al.  Numerical calculation of multiphase fluid flow , 1975 .

[27]  R. Clift,et al.  A NOTE ON TERMINOLOGY - CLUSTERS AND AGGLOMERATES , 1992 .

[28]  Masayuki Horio,et al.  THREE-DIMENSIONAL FLOW VISUALIZATION OF DILUTELY DISPERSED SOLIDS IN BUBBLING AND CIRCULATING FLUIDIZED BEDS , 1994 .

[29]  F. E. Milioli,et al.  Numerical simulation of fluid flow in CFB risers: A turbulence analysis approach , 2005 .

[30]  Filip Johnsson,et al.  Characterization of fluidization regimes by time-series analysis of pressure fluctuations , 2000 .

[31]  Lounes Tadrist,et al.  Numerical study of cluster formation in a gas–particle circulating fluidized bed , 2000 .

[32]  S. Sundaresan,et al.  The role of meso-scale structures in rapid gas–solid flows , 2001, Journal of Fluid Mechanics.

[33]  Tron Solberg,et al.  Evaluation of a Three-Dimensional Numerical Model of a Scaled Circulating Fluidized Bed , 2001 .

[34]  C. Wen.  Mechanics of Fluidization , 1966 .

[35]  John F. Davidson,et al.  Circulating fluidised bed hydrodynamics , 2000 .

[36]  Dimitri Gidaspow,et al.  Hydrodynamic simulation of gas-solid flow in a riser using kinetic theory of granular flow , 2003 .

[37]  T. B. Anderson,et al.  Fluid Mechanical Description of Fluidized Beds. Equations of Motion , 1967 .

[38]  S. L. Soo,et al.  Fluid dynamics of multiphase systems , 1967 .

[39]  D. Wasan,et al.  Continuous separation of fine particles in nonaqueous media in a lamella electrosettler , 1990 .