5 - Engineering and Applications of Recirculating and Jetting Fluidized Beds

Abstract

This chapter discusses the engineering and applications of recirculating and jetting fluidized beds. In a conventional fluidized bed, fluid under pressure is passed through a bed of solids via a distributor plate. At a fluid velocity beyond the minimum fluidization or minimum bubbling velocity, visible bubbles appear. The fluid thus passes through the bed in two phases: the bubble and the emulsion phases. The bubble-induced solids mixing and circulation provide the liquid-like behavior of a bed of otherwise immobile solids. The liquid-like behavior of a fluidized bed allows continuous feeding and withdrawal of bed material. The vigorous mixing of solids in the bed gives rise to a uniform bed temperature even for a highly exothermic or endothermic reaction. This leads to an easier control and operation. The advantages of a fluidized bed, compared to other modes of contacting, such as a packed bed are numerous and they are described in details in standard textbooks on fluidization.