Elutriation of fine particles from batch gas—solid fluidized bed — at sufficiently high freeboard height —

Abstract

An experimental and semi-theoretical work on the elutriation of fine particles from a fluidized bed was carried out. The fluidizing equipment, consisting of an iron pipe of 3 in i.d., was designed in such a way that its freeboard height can be adjusted properly. At the different freeboard heights and air flow rates, the accumulated weights of fine particles with time were measured. The same procedure was repeated for different initial contents of the fine particles in the bed. In order to interpret the experimental results, a simple model was constructed by assuming that the fine particles were transported only by convection of gas. The model included two parameters; one was a critical height above which the transport of fine particles was controlled by convection of gas, and the other was the elutriation rate constant. The critical height was estimated experimentally. The elutriation rate constant was determined by a method proposed in this work. It was found that the elutriation rate constant was independent of the freeboard height and that its value was consistent with the calculated value based on the correlation of Wen and Hashinger [3]. Further, a physical meaning of the elutriation rate constant was eluciated from this model.