CFD-simulation of a circulating fluidized bed riser--颗粒学报PARTICUOLOGY

Hartge, E.-U., Ratschow, L., Wischnewski, R., & Werther, J. (2009). CFD-simulation of a circulating fluidized bed riser. Particuology, 7(4), 283–296. https://doi.org/10.1016/j.partic.2009.04.005

CFD-simulation of a circulating fluidized bed riser

Ernst-Ulrich Hartge^*, Lars Ratschow, Reiner Wischnewski, Joachim Werther

Hamburg-University of Technology, Institute of Solids Process Engineering and Particle Technology, D-21071 Hamburg, Germany

10.1016/j.partic.2009.04.005

Volume 7, Issue 4, August 2009, Pages 283-296

Received 3 April 2009, Accepted 11 April 2009, Available online 8 July 2009.

E-mail: Hartge@tuhh.de

Highlights

Abstract

In the current work, a model of the fluid mechanics in the riser of a circulating fluidized bed (CFB) has been implemented using computational fluid dynamics (CFD). The model developed shall be used in future as the basis of 3D-reactor model for the simulation of large scale CFB combustors. The two-fluid model (TFM) approach is used to represent the fluid mechanics involved in the flow. The computational implementation is accomplished by the commercial software FLUENT. Different closure formulations are tested on a simplified geometry. Two different turbulence formulations, namely the swirl modified RNG k–ɛ model and the Realizable k–ɛ model, are tested in combination with two different approaches to solid phase turbulence, namely the dispersion and per phase approach. One focus of the current work is put on the study of different drag correlations. Besides the drag correlations by Syamlal et al. [Syamlal, M., Rogers, W., & O’Brien, T. J. (1993). MFIX documentation theory guide. Technical Report DOE/METC-94/1004, U.S. Department of Energy (DOE). Morgantown Energy Technology Center: Morgantown, WV] and Gidaspow [Gidaspow, D. (1994). Multiphase flow and fluidization. New York: Academic Press] the EMMS model has been used to determine the momentum exchange between the two phases. The resulting formulation is then used to simulate a 1-m × 0.3-m cold CFB setup and is validated by experimental results [Schlichthärle, P. (2000). Fluid dynamics and mixing of solids and gas in the bottom zone of circulating fluidized beds. Unpublished doctoral dissertation, Technische Universitaet Hamburg-Harburg, Shaker Verlag: Aachen].

Graphical abstract

Keywords

Circulating fluidized bed; Two-fluid model; EMMS model; Drag correlations

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