Relationship between flow structure and transfer coefficients in fast fluidized beds

In this paper, the relationships between the bed structural parameters and momentum transfer, mass transfer and heat transfer in fast fluidized beds are analyzed for Geldart A or B particles. The influence of dispersion and aggregation of particles on the mass transfer coefficient and heat transfer coefficient is discussed. The equations for calculating the drag force coefficient, mass transfer coefficient and heat transfer coefficient in fast fluidized beds are developed based on eight structural parameters (U(fd), U(fc), U(pd), U(pc), d(c), f, epsilon(d) and epsilon(c)) of heterogeneous beds. which can be solved by the Energy-Minimization Multi-Scale (EMMS) model. The drag force has been calculated based on the local bed structural parameters and the calculated solids flux and solids concentration are compared with the experimental data in the literature. For the heat transfer and mass transfer, the averaged bed structural parameters are employed to calculate the averaged heat transfer and mass transfer coefficients, and the results are compared with the experimental data from the literature. The simulating results are in good agreement with experimental data. (C) 2010 Elsevier B.V. All rights reserved.

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

[2]  Bolun Yang,et al.  Multi-Scale Study on the Secondary Reactions of Fluid Catalytic Cracking Gasoline , 2009 .

[3]  D. Gidaspow,et al.  Hydrodynamics of circulating fluidized beds: Kinetic theory approach , 1991 .

[4]  L. Huilin,et al.  Numerical analysis of interphase heat and mass transfer of cluster in a circulating fluidized bed , 2009 .

[5]  Joachim Werther,et al.  Two‐dimensional model for circulating fluidized‐bed reactors , 1996 .

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

[7]  F. Scala.  Mass transfer around freely moving active particles in the dense phase of a gas fluidized bed of inert particles , 2007 .

[8]  Wei Ge,et al.  CFD simulation of concurrent-up gas-solid flow in circulating fluidized beds with structure-dependent drag coefficient , 2003 .

[9]  Ronald W. Breault,et al.  A review of gas–solid dispersion and mass transfer coefficient correlations in circulating fluidized beds , 2006 .

[10]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[11]  O. Bolland,et al.  DESCRIBING MASS TRANSFER IN CIRCULATING FLUIDIZED BEDS BY OZONE DECOMPOSITION , 2001 .

[12]  Jinghai Li,et al.  A multiscale mass transfer model for gas-solid riser flows: Part 1 - Sub-grid model and simple tests , 2008 .

[13]  R. Higbie,et al.  The Rate of Absorption of a Pure Gas into a Still Liquid during Short Periods of Exposure , 1935 .

[14]  Mooson Kwauk,et al.  Micro-visualization of clusters in a fast fluidized bed , 1991 .

[15]  Ronald W. Breault,et al.  Mass transfer in the core-annular and fast fluidization flow regimes of a CFB , 2009 .