Simulation Analysis Of Upflow Anaerobic Sludge Blanket Based On Computational Fluid Dynamics

UASB reactor is an important structure in the anaerobic wastewater treatmentprocess. The rational design of the bottom of the water distribution and the foldingangle of three-phase separator is critical to operate efficiency of the UASB reactor.From hydraulics to consider, This paper use the FLUENT commercial software tonumerical simulate the UASB reactor on a different form of water distribution andthree-phase separator flap angle, establish liquid model and gas-liquid, liquid-solidtwo-phase model of the UASB reactor, it is very important to reference to devise andoptimize UASB reactor.The internal flow field of UASB reactor is very complicated. Firstly, the liquidflow field in the UASB reactor was simulated. This pepper analyzes UASB differentstructural parameters: uniform water distribution, parabolic water distribution andtrapezoidal water distribution three different flow rate forms and three-phaseseparator flap angle of30°,45°,50°,60°, to the Influence of flow patterns withinthe reactor. At the same time, due to the UASB in flow field changes over time,therefore the flow field was set to non-steady flow, and the RNG k-ε model with lowReynolds number was selected for turbulence model, by simulation to determine theoptimization program.At the second part of this paper, by gas-liquid two-phase flow simulation, weobtained the UASB internal gas volume fraction figure at different time, explored theimpact of the gas-liquid separation at different flow rate form and three-phaseseparator folding angle, the simulation results show that:①uniform inlet water formbasically as same as trapezoidal form affect on UASB reactor internal gas-liquidseparation, but the trapezoidal inlet water form improve the gas-liquid mixinguniformity of UASB reaction zone;②three-phase separator device folding angle30°is not conducive to the gas-liquid two-phase separation within UASB reactor.In this paper, the solid phase was Considered to homogeneous particles, use theEulerian multiphase model, and establish a UASB reactor liquid-solid two-phasemodel, and analyze the impact of different three-phase separator folding angle onliquid-solid two-phase separation, the results show that: three-phase separator flapangle of45°to50°, more conducive to the liquid-solid two-phase separation.Conclusions of this study can help people to fully understand the influencingfactors and changes in laws of the internal flow field of UASB anaerobic sludge bed,provide a useful reference and technical support for optimizing the design and improving efficiency in actual project, will also promote the UASB anaerobic thesludge bed design standards.