A CFD-DEM study of bubble properties in fluidzed beds operated with a single jet

Bubbles properties play an important role in determining the characteristics of gas-solid fluidized beds and thus influence the bed performance significantly. In this work, the bubble properties are studied by the combined approach of CFD and DEM for bubbling gas-solid fluidized beds operated with a continuous central jet. The process of the continuous injection of a central air jet to the bed is successfully reproduced featured with the formation of series of bubbles which rise through the bed and burst at the bed top. The bubbles are categorised as two types: primary/leading bubbles and trailing bubbles. The size of the primary bubble keeps on increasing with bed height while the size of the trailing bubble decreases since trailing bubble is coalescing with the primary bubble. The primary bubbles although formed at different times are of similar shape while the trailing bubbles are generally elongated in shape. The bubble velocity is distinctly different for primary and trailing bubbles.