(74h) Fundamental Prediction of Agglomeration and Entrainment Rates for Cohesive Powders in a Riser Flow
Empirical models for the entrainment rates of non-cohesive powders in fluidized bed systems can vary by several orders of magnitude in their predictions for the same system ((Chew et al. 2015)). For cohesive particles, the formation and breakage of agglomerates results in further uncertainty to the entrainment rate. In this work, a fundamental approach is used for entrainment prediction. Specifically, the population balance is coupled with kinetic-theory-based balances. This new continuum framework is based on fundamental closures for the birth and death rates due to aggregation in the population balance. These novel closures take into account the effect of impact velocity (the granular temperature) on the outcome of a collision as agglomeration, rebound, or breakage. The agglomerate size distribution and entrainment rates predicted by the population balance model are compared to discrete element method (DEM) simulations of a riser flow as well as to experimental results.
Chew, J. W., A. Cahyadi, C. M. Hrenya, R. Karri and R. A. Cocco (2015). "Review of entrainment correlations in gasâsolid fluidization." Chemical Engineering Journal 260: 152-171.