From discrete particle model to a continuous model of Geldart A particles

Areliable description of dense gas?solid two-phase flows of Geldart A particles in gas-fluidized beds at life-size scale is of great practical importance in process industries. The classical two-fluid model, based on the kinetic theory of granular flows (KTGF), provides a very promising theoretical framework for predicting large-scale gas?solid twophase flows. However, thus far the two fluid model has not been successful in describing gas?solid flows of Geldart A particles. As the kinetic theory was originally developed for cohesiveless particles, it is essential to check if the theory can still work for Geldart A particles, which are slightly cohesive. In this research, a soft-sphere discrete particle model (DPM) is used to study the detailed particle?particle interactions in periodic boundary domains, where interparticle van der Waals forces are taken into account, with no gas phase present. In our simulations, we (1) compare the results for both the hard-sphere and the soft-sphere discrete particle model for cohesiveless particles, with the theoretical predictions obtained from the kinetic theory of granular flows, and (2) study the effect of the cohesive forces in the soft-sphere model and explore a way to modify the current kinetic theory according to the soft-sphere DPM simulation results. The information obtained from these simulations can be further incorporated into the KTGP based two-fluid model. Author(s): M. Ye1 | M. A. Van Der Hoef2 | J. A. M. Kuipers3

[1]  Aibing Yu,et al.  Numerical simulation of the gas-solid flow in a fluidized bed by combining discrete particle method with computational fluid dynamics , 1997 .

[2]  Y. Tsuji,et al.  Discrete particle simulation of two-dimensional fluidized bed , 1993 .

[3]  William G. Hoover,et al.  Melting Transition and Communal Entropy for Hard Spheres , 1968 .

[4]  Bjørn H. Hjertager,et al.  An experimental and numerical study of flow patterns in a circulating fluidized bed reactor , 1996 .

[5]  Gilles Flamant,et al.  Lagrangian approach for simulating the gas-particle flow structure in a circulating fluidized bed riser , 2002 .

[6]  Anna Walsh.  STUDIES IN MOLECULAR DYNAMICS , 1965 .

[7]  D. Geldart.  Types of gas fluidization , 1973 .

[8]  Jonathan Seville,et al.  Interparticle forces in fluidisation: a review , 2000 .

[9]  He Yurong,et al.  Hydrodynamics of gas-solid flow around immersed tubes in bubbling fluidized beds , 2004 .

[10]  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 .

[11]  Hamid Arastoopour,et al.  Extension of kinetic theory to cohesive particle flow , 2002 .

[12]  T. G. Cowling,et al.  The mathematical theory of non-uniform gases , 1939 .

[13]  Jam Hans Kuipers,et al.  Hydrodynamic Modeling of Gas/Particle Flows in Riser Reactors , 1996 .

[14]  K. E. Starling,et al.  Equation of State for Nonattracting Rigid Spheres , 1969 .

[15]  J. M. Haile,et al.  Molecular dynamics simulation : elementary methods / J.M. Haile , 1992 .

[16]  Jinghai Li,et al.  Particle-motion-resolved discrete model for simulating gas–solid fluidization , 1999 .

[17]  J. Israelachvili.  Intermolecular and surface forces , 1985 .

[18]  Masayuki Horio,et al.  Numerical simulation of cohesive powder behavior in a fluidized bed , 1998 .

[19]  B. Alder,et al.  Studies in Molecular Dynamics. II. Behavior of a Small Number of Elastic Spheres , 1960 .

[20]  Jam Hans Kuipers,et al.  A numerical study of fluidization behavior of Geldart A particles using a discrete particle model , 2004 .

[21]  Goodarz Ahmadi,et al.  An equation of state for dense rigid sphere gases , 1986 .

[22]  M. Adams,et al.  Discrete particle-continuum fluid modelling of gas–solid fluidised beds , 2002 .

[23]  Sankaran Sundaresan,et al.  Gas-particle flow in a duct of arbitrary inclination with particle-particle interactions , 1993 .

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

[25]  H. Arastoopour,et al.  Simulation of particles and gas flow behavior in the riser section of a circulating fluidized bed using the kinetic theory approach for the particulate phase , 2000 .

[26]  P. Cundall,et al.  A discrete numerical model for granular assemblies , 1979 .

[27]  J. Kuipers,et al.  Discrete particle simulation of bubble and slug formation in a two-dimensional gas-fluidised bed: A hard-sphere approach. , 1996 .

[28]  D. Jeffrey,et al.  Kinetic theories for granular flow: inelastic particles in Couette flow and slightly inelastic particles in a general flowfield , 1984, Journal of Fluid Mechanics.

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

[30]  J. Kuipers,et al.  Lattice-Boltzmann simulations of low-Reynolds-number flow past mono- and bidisperse arrays of spheres: results for the permeability and drag force , 2005, Journal of Fluid Mechanics.

[31]  W. W. Wood,et al.  Molecular dynamics calculations of the hard-sphere equation of state , 1984 .

[32]  B. Alder,et al.  Phase Transition for a Hard Sphere System , 1957 .

[33]  S. Savage.  Streaming motions in a bed of vibrationally fluidized dry granular material , 1988, Journal of Fluid Mechanics.

[34]  R. Jackson,et al.  Gas‐particle flow in a vertical pipe with particle‐particle interactions , 1989 .

[35]  Yonghao Zhang,et al.  Continuum modelling of granular particle flow with inelastic inter-particle collisions , 2003 .