SOLIDS CIRCULATION IN SPOUTED AND SPOUT-FLUID BEDS WITH DRAFT-TUBES

A 20 cm semi-cylindrical spout-fluid bed with a draft-tube has been used to investigate the effect of various physical parameters on the solids circulation rate, A new method has been developed by which these data can be easily and accurately collected. Equations are presented which can be used to predict the maximum attainable solids circulation rate and the spouting velocity required to achieve this maximum for the unit operating in spouting mode. The circulation trends are shown to be a direct result of the phenomena of entrainment and jetting occurring in the entrainment zone investigated visually with a video camera. Preliminary gas bypassing experiments were also performed which show the ability to almost eliminate spout gas bypassing to the annulus with appropriate auxiliary gas addition.