Table of Contents
Journal of Powder Technology
Volume 2014, Article ID 980416, 6 pages
Research Article

Choking Affects the Operation Diagram of a CFB Riser

1Department of Chemical Engineering, KU Leuven, De Croylaan 46, 3001 Heverlee, Belgium
2School of Engineering, University of Warwick, Coventry CV4 7AL, UK
3Process and Environmental Technology Laboratory, Department of Chemical Engineering, KU Leuven, 2880 Sint-Katelijne-Waver, Belgium

Received 30 October 2013; Revised 26 December 2013; Accepted 10 January 2014; Published 4 March 2014

Academic Editor: Jürgen Tomas

Copyright © 2014 H. L. Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Experiments in 3 different CFB risers have confirmed that common riser operations can be hampered in a well-defined (U, G) range where choking occurs. Geldart A-type powders were investigated. Experimental results of the choking velocity were empirically correlated, being about 30% lower than predicted by the correlation of Bi and Fan, but largely exceeding other predictions. Introducing the findings into the operation diagram presented by Mahmoudi et al. adds a region where stable riser operation is impossible. The adapted diagram enables CFB designers to better delineate the operating characteristics.