Numerical Simulation Analysis Of Anaerobic Reactors

Anaerobic biological treatment technology has been widely used in industrial wastewater treatment for its high handling performance,low treatment cost and the produce of available methane energy.With the rapid development of anaerobic biological treatment technology,and a variety of anaerobic biological treatment reactors appeared,including upflow anaerobic sludge blanket?UASB?and internal circulation anaerobic reactor?IC?.Because of the complexity of three phase flow inside the two reactors,there is not a mature,systematic method for UASB reactor design.The reports on design are almost experiential and half-experiential formulas and there was blindness in controlling the operation conditions.In recent years,only a few people study the hydraulic mixing characteristics of the two reactors by fluent method,so using computational fluid dynamics numerical simulation method to study the flow characteristics of the two reactors has great reference value.In this paper,gas-liquid two-phase flow in UASB and IC reactor were studied using CFD method.The influence of different OLR?angle of three-phase separator and water distribution ways on flow field in UASB reactor were investigated;The effect of flow field in IC reactor under different H/D?D_r/D and angle of three-phase separator was investigated.The results show that:?1?The numerical simulation of UASB reactor:1)When the angle of three-phase separator was 50oand four water inlets,the effect of flow field under different influent flow rate?0.0171?0.0213?0.0257m³/d?was studied.When influent flow rate was 0.0213⁰.0257m³/d?5⁶ kgCOD/?m³·d??,which the features of hydraulic mixing was best.2)When the influent flow rate was 0.0213m³/d?OLR 5kgCOD/?m³·d??and four water inlets,the effect of flow field under different angle of three-phase separator?40°?45°?50°?55°?was studied.When angle of three-phase separator was 50°,which the features of hydraulic mixing was best and solid liquid performs excellent separation efficiency.3)When the influent flow rate was 0.0213 m³/d?OLR 5kgCOD/?m³·d??and angle of three-phase separator was 50°,the effect of flow field under different number of water inlets?1?2?3?4?water distribution uniformity?was studied.When water uniformly entered from bottom of the reactor,which the features of hydraulic mixing was best.?2?The numerical simulation of IC reactor1)When Dr/D was 0.081,a maximum value of Q_IC?0.0079m³/h?was reached under conditions of H/D?5?,angle of three-phase separator?50°?.2)When H/D was 3,a maximum value of Q_IC?0.011m³/h?was reached under conditions of Dr/D?0.081?,angle of three-phase separator?50°?.3)When angle of three-phase separator was 50°,a maximum value of Q_IC?0.0119m³/h?was reached under conditions of H/D?3?,Dr/D?0.081?.