The Hydrodynamics Of Upflow Anaerobic Sludge Blanket Reactor

The Upflow Anaerobic Sludge Blanket Reactor(UASB)has the characteristics of high volumetric load and secondary energy generation,and is widely used in industrial water treatment.However,during the operation of the UASB,the initial startup of the reactor is difficult and the startup cycle is long.Due to the complex three-phase flow field inside the UASB,in addition to the research on the biochemical reaction mechanism that has been perfected,the internal flow field of the UASB reactor needs to be explored from the perspective of fluid mechanics to solve the existing problem of UASB.In this paper,the laboratory UASB reactor was used as the object,and the flow field numerical simulation software Fluent was used to simulate the internal flow field of the reactor under different operating conditions and different structural conditions.The results show that the proposed calculation model for the large difference particle flow of the bioreactor is in good agreement with the experimental results with an error of 20%.Using the interphase drag model,the main design defects of the existing UASB reactor in the laboratory were proved to be the water distributor and the three-phase separator.The reasons for the sludge loss were analyzed.The effects of different operating conditions on the flow field in UASB were investigated,and the relationship between the range of liquid velocity and the expansion ratio of blanket under the ideal liquid operating rate was obtained.According to the structural improvement of the existing reactor,the optimal dimension of the water distribution dimension ? is 150 to 600,and the ratio of the optimal water distributor installation height to the initial sludge blanket height is 0.2: 1.The best reaction of the height to diameter ratio is 15.The optimized double-inclined cloth water can significantly improve the bottom muddy water mixing effect;the optimized two-stage ring-plate type three-phase separator can improve the gas collection efficiency and alleviate the mud running phenomenon.In this paper,the optimal operating conditions and optimal structure of the UASB reactor are established by numerical simulation of flow field,which has a certain guiding effect on the design and operation of the UASB reactor.