Slip Velocity in Downer Reactors: Drag Coefficient and the Influence of Operational Variables

Abstract

Cluster formation in downer reactors is considered a most important factor influencing slip velocity between the flowing phases. This study investigates the formation of clusters using CREC-GS-Optiprobes. This probe is a nonintrusive device that records information from a well-defined optical measuring volume. This probe can provide accurate measurements tracking closely gas−solid flows in downer units. This study shows that cluster drag coefficients can be correlated as function of both Reynolds number and number of particles contained in agglomerates. This yields a close to linear relationship between cluster size and average slip velocity.