May 23, 2017
Yeook Arrington, S.B. Reddy Karri, Ray Cocco, 12th International Conference on Fluidized Bed Technology, Krakow, Poland
Particle attrition can be a major issue in using catalyst particles in fluidized beds and circulating fluidized beds. Particles tend to break down via two mechanisms – abrasion and fragmentation. Abrasion can be defined as constituent particles attriting off the surface of the parent particles. The resulting size distribution of parent particles shows almost no change in cut sizes under this abrasion attrition mechanism. With the fragmentation attrition mechanism, the parent particles are breaking down to intermediate cut sizes as well generating constituent particles. This results in a shift in the size distribution of parent particles in addition to producing finer constituent particles.
Several methods are available in characterizing attrition characteristics of catalyst particles. Jet cup attrition testing is a common method for ranking of relative attrition characteristics by comparing their attrition indices. PSRI jet cup attrition testing is a two-step process. The first step in jet cup attrition testing is to identify the threshold velocity and to determine the optimum jet velocity for evaluating particle attrition. The threshold velocity represents the gas jet velocity at which the transition of the attrition mechanism from abrasion to fragmentation takes place.