Numerical study of the segregation of pyrolized char in a bubbling fluidized bed according to distributor configuration

Abstract

In this study, computational particle fluid dynamics were applied to investigate the segregation characteristics of char particles in a bubbling fluidized bed. We examined the bubble behavior and the consequent segregation of char particles with respect to the nozzle arrangement of the distributor in a bubbling fluidized bed. The segregation characteristics of a mixture of char and sand particles were analyzed in terms of pressure fluctuation, bubble diameter, the number of bubbles, and the mixing index. It was observed that an increasing number of nozzles resulted in a decreased bubble diameter, which led to better segregation between char and sand particles. The mixing index of char and sand particles decreased from 0.75 to 0.42 from nnozzle = 8 to nnozzle = 17, then increased to 0.50 at nnozzle = 20. When the number of nozzles was more than nnozzle = 17, the bubble diameter increased, and the number of bubbles decreased because the bubbles coalesced with surrounding bubbles.