The clustering annular flow model of circulating fluidized beds.

Abstract

The Clustering Annular Flow Model (CA model) is presented to describe the annular flow structure in the main column of a circulating fluidized bed (CFB). With the present model the flow parameters for a CFB including the dimensionless radius of the core α can be estimated, given the values of both the diameter and the voidage of the cluster phase.The model was successfully validated by comparison of values of α experimentally determined with those predicted from the model and observed cluster parameters. With consideration of the cluster formation it became possible to give a quantitative explanation of the annular flow structure and the high gas-solid slip velocity so far observed in circulating fluidized beds.