Mass Transfer Between Solid Particle And Liquid Flow In The Liquid-Solid Mini-Fluidized Bed

Liquid-solid fluidization is an important operation mode of process industries,and has a wide range of practical applications.With the development of techniques of chemical process intensification,the liquid-solid mini-fluidized bed is being paid more attention.The hydrodynamics in the liquid-solid mini-fluidized bed has been studied.However,few investigations on interphase mass transfer in this type of fluidized bed could be found in open literature.That is the basic contents of this thesis.Different from the gas-liquid mass transfer the external surface of the solids is un-deformable and the liquid-solid interfacial area remains constant regardless of the hydrodynamics conditions as long as the external particle surface remains completely wetted.Studies of mass transfer for the liquid-solid mini-fluidized beds are limited to date.The purpose of the present study is to measure the saturated concentration of benzoic acid solution in a liquid-solid mini-fluidized bed,and to calculate the liquidsolid mass transfer coefficient and to check the effects of different factors on the mass transfer coefficientThe solid-liquid mass transfer experiments were conducted in a liquid-solid mini-fluidized bed vertical Plexiglas column with bed inner diameter of 3mm and bed height of 10cm,using water as liquid phase and benzoic acid particles as solid phase respectively.The solid-liquid fluidization was observed in an up-flow operation mode.The benzoic acid solution was prepared by dissolving benzoic acid particles into water.The saturated concentration of benzoic acid solution was measured by using the UV-Spectrometry at 254nm and determined by using UV-analyses.The solid-liquid mass transfer coefficient was experimentally calculated and influence of superficial liquid velocity,particle size and fluidized bed height on the mass transfer coefficient were obtained first time.These results provide a basis for the mass transfer rate in the liquid-solid and gas-liquid-solid mini-fluidized beds.