CFD Simulation And Optimization Of Self-stirred Anaerobic Digestion Tank

At present,the anaerobic process in the biomass solid waste,urban waste,eat hutch garbage and sewage treatment have been widely used.Material in the process of anaerobic mixing has an important influence to improve the effect of anaerobic treatment,the biomass of anaerobic fermentation and sewage anaerobic digestion process usually adopt the method of mechanical stirring make biomass material or solid-liquid mixture.Small scattered and application of anaerobic reactor(anaerobic fermentation tank,septic tanks and sewage purification tank)due to the condition,and operational cost,the influence of such factors as the anaerobic process is usually not install mechanical stirring,and thus cannot give full play to the role of anaerobic process.By setting U tube in the anaerobic reactor,using biogas generated from the anaerobic reaction potential energy for material for automatic mixing self-agitated tank solve the problem that the small anaerobic reactor material or solid-liquid mixture.However,since the mixing material mix of anaerobic reaction tank by reaction tank internal structure,material,or the sludge had a great effect on viscosity and density,the influence is difficult to completely through the method of experimental research.Computational Fluid Dynamics,(CFD),as a research method,studied in the mixing of anaerobic reaction tank(by three partition is divided into four regions),structure(reaction groove space allocation proportion,u-shaped tube diameter and reaction groove plate location)and the density and viscosity of material or the sludge have important influence in mixing,the influence of the main conclusions are as follows:When the sludge SS in 0-9.35 g/L,viscosity at 1-120 mPa·s,stir this since the anaerobic reaction tank for solid-liquid mixed all have certain effect,and the smaller density and viscosity,the better the mixing.With the increase of 1st area,the proportion of the reactor,in the 3rd and 4th area at the bottom of the sludge or material disturbance in smaller and smaller.At the bottom of the 1st area and the 2nd area of the sludge or spread in the area of material quantity more and more;When the u-shaped pipe in the reaction tank diameter greater than 2 cm,on the effects of solid-liquid mixture will have adverse effect,when U tube diameter is higher than 5 cm,little mixing effect of the reaction groove.Reactor fluid density and viscosity can increase with the increase of the u-shaped tube diameter size;In the 3rd partition of reactor,a distance of 5 cm at the bottom of the 1st baffle plate distance,1st area and the 2nd area at the bottom of the sludge or materials by the disturbance of the biggest,the third at the bottom of the baffle plate distance of 10 cm,3rd and 4trh area at the bottom of the sludge or materials received disturbance is the largest.The research achievements of this paper improve the internal factors from the mixing of anaerobic reaction tank for them the effect of fluid flow and put forward its significance in the field of other mixing.