Heat Transfer in Fluidized Beds

Abstract

This chapter describes the phenomena of heat transfer among the fluidized particles and the fluid and the fluidized bed and the walls of the container or immersed solid objects, and lists some applications of fluidized beds to processes where heat-transfer operations are dominant. The fluid used to fluidize the particles may be either a gas or a liquid. Basic quantities used in describing a fluidized bed are the minimum fluidization velocity and the minimum fluidization void fraction or voidagc that is associated with it. Because of the excellent contacting ability between the solid and fluid phase, the fluidized bed has found vast industrial applications in areas involving heterogeneous heat transfer, mass transfer, and chemical reactions. This is particularly true of the gas-fluidized bed. The main industrial uses of fluidized beds are in the oil industry. There the fluidized beds serve as reactors for production of high-octane gasoline, thermal cracking of petroleum feed stocks, catalytic cracking of heavy hydrocarbons to lower molecular-weight compounds, and carbonization and gasification of oil shale, coal, and coke. Finally, this chapter concludes that in the last 20 years, a vast body of literature has been accumulated dealing with the fluid dynamics, heat transfer, mass transfer, chemical reactions, and industrial applications of fluidized beds.