The Flow Simulation And Optimization Design Of Anaerobic Reactor

With the growing of sludge from wastewater plant day by day,it is urgent for the treatment and disposal of sludge.Anaerobic digestion technology is considered t o be one of the most economic and effective sludge treatment process.This process can convert organic matter of sludge into stable inorganic matter,meanwhile it also can produce methane as utilizable energy.Anaerobic reactor is the precondition of anaerobic digestion reaction.The way of stir is often one of the key factor that determine the success or failure of the reaction in the design of the reactor,because it has great influence on the mass transfer efficiency between the materials.This study through the reactor design optimization,research performance and operation condition of the reactor through water experiment firstly,then with the help of computational fluid dynamics technology research internal fluid in different mode of stir by numerical simulation,finally determine the optimal condition of reaction,and what need to improve.The reactor we design and production in this study use acrylic material,the diameter is 600 mm,overall height is 1800 mm,total volume is 0.454m~3,effective volume is 0.4 m~3.In the first place,the reactor as research object,with plastic particles carrier instead of the sludge through the clear water flow state experiment studied flowing state variation under different ways of stir,find that it is the most evenly mixed under the rotate speed of 190r/min of mechanical agitation,mixing time reduces with the increase of rotational speed,the time is least under the rotate speed of 190r/min;combination of mechanical agitation and gas agitation,it is the most evenly mixed under the rotate speed of 160r/min,the mixing time is least under the rotate speed of 190r/min.Through the study also find that when we add gas agitation,the axial flow effect is enhanced in the interior of reactor,and make the mixing effect better.The mixing effect of gas agitation increases with the increase of the gas capacity,the flow velocity increases with the increase of the gas capacity,the mixing time is inversely proportional to the gas capacity?Next,we study the reactor flow field with numerical simulation through computational fluid dynamics commercial software FLUNE T.The simulation study of reactor flow field under the mechanical agitation shows that,the most speed in reaction zone exceed 0.1m/s under the rotate speed of 160r/min,e nergy consumption is lower than 190r/min,therefore the optimal rotate speed is 160 r /min under the mechanical agitation.The simulation study of reactor flow field under the gas agitation shows that,the distinct backmixing phenomenon and lateral pulsation appears in flow field,lead to the phenomenon of backflow and eddy,there are several distinct dead zones in reaction zone.The simulation study of reactor flow field under the combination of the first two types shows that,the dead zones which form the fi rst two types of mixing are basically eliminated,nevertheless,the excessive low or excessive low rotate speed will result in backmixing phenomenon,the local backmixing phenomenon is basically eliminated when rotate speed is 120r/min,at this time the mixing effect is best,therefore the optimal rotate speed is 120r/min under the combination of the first two types.