Study On The Fluidization Characteristics Of Three Phase Multistage Biological Fluidized Bed And Carrier

In order to solve the defect of traditional single fluidized bed reactor, such as bubble growing easily lead to the coalescence phenomenon, serious fluid backmixing and low mass transfer efficiency etc,we add some sieve plate to distribute circulating liquid better and broke bubble, increase the gas-liquid contact area and thereby strengthening the between the gas-liquid mass transfer, so the above-described conventional problems can be preferably solved by multistage fluidized bed technology.In this paper, the mass transfer characteristics and backmixing characteristics of the multistage fluidized bed is carried through the cold model test. In the study, the coke particles is used as solid phase carrier, water as liquid phase, air as gas phase. As solid phase playing an important role in a biological fluidized bed such as influencing on hydrodynamics and biochemical reactions, so the physical property and chemical property of the coke breeze is also studied in depth in this paper.Some data of the coke breeze is measured, such as size range, mean particle size, bulk density, true density, porosity, water absorption and the BET surface characteristics.These data prove the coke breeze possessing rough surface, irregular shape, big surface area, suitable porosity and specific gravity. Additionally, coke breeze is cheap and easy to get, so it is suitable as carrier for biological fluidized bed for biological wastewater treatment.Determination of the use of aeration overall mass transfer coefficient of oxygen mass transfer characteristics of devices with superficial gas velocity, superficial liquid velocity, solid phase holdup relationship. By measuring the oxygen mass transfer coefficients of fluidized bed,we can get the relationship of gas-liquid mass transfer characteristics with the superficial gas velocity, superficial liquid velocity and solid holdup.The mean residence time and backmixing performance is measured by conductivity measurement, The results indicate that the greatest impact on the liquid backmixing is the superficial liquid velocity. Backmixing increase with the superficial liquid velocity in the experimental range, but the superficial gas velocity, superficial liquid velocity and the content of carriers affecting on mean residence time is just the opposite.