Choking Affects the Operation Diagram of a CFB Riser

Abstract

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.