文献翻译-搅拌器设计的一般程序

外文翻译AGeneralProcedureforMixerDesignAbstract:Thispaperintroducedtheprocedureofchemicalmixerdesignasarule.Forasimplestliquid-liquidmixingproject,theprocedurecontains5stepstofitthedemandsofuser,suchasthedeterminationoftype,dimensions,speedandpowerofthemixer.Thiscangivereferencefordesigner.Keywords:chemicalengineering;designprocedure;mixerStirringcanacceleratethechemicalprocessofheattransferandmasstransferinthepetrochemical，Extensiveuseofworkequipment.Stirtheobjectcanbeliquids,solidsandgases,includingliquidMajority.Themostcommonliquidiswater,itsviscosityisverylow.Buttheliquidalsomaybeverythick,suchasbutteratroomtemperatureforupto1000000cP(viscositydegrees,1cP=10-3Pas,thesamebelow).Ifaddedtoomuchliquid-solids,suchassand,willlosemobility,amudpie.Thismaterialcanalsobestirred,notwithinthescopedescribedinthisarticle.Gasisnottoomuchleadtolossofmobility,butfromthefoam.Thesimplestistomixthetwoissuescouldbemixingmiscibleliquids.Therequirementsofusersisoftentheextentofmixingtimeandmixing.Successfuldesignshouldbeabletomeettheserequirements,andthattheyaremoretospendonmaintenance.Wealwayspursuethegoalistechnology,machineryandthecostofthebalanceamongthethree.Miscibleliquidmixingcannotbemuchmorecomplex,accordingtotherequirementsofusers,sometimeshigh-power,high-speed,highshearemulsificationequipment.Thesecondcommonissueisthesuspensionofsolidparticles,whichcanbecanbedissolved,itcanbeavaluablesolidmaterialintheleaching.Canhaveachemicalreaction,canonlystorethemix.Thethirdisaliquid2gasmixing,commonlyusedinwastewatertreatmentaerationequipment.Usuallyagitator(mixer)bythemotorsastheprimemover(motor,electric,pneumaticorhydraulic),Reducer(reducer,gearbox),andthereduceroutputshaftconnectedtotheshaftandtheshaftoftheimpellerinstalledinthemixingcomposition.Slowingthebodythroughabracketorbaseplateisconnectedwiththemixingcontainer.Whenthepressureinsidethecontainer,thestirringshaftthroughthefloorintothecontainershouldhaveaseal,oftenpackingsealormechanicalseal.Boththemotorandthesealisusuallypurchased,thestudyfocusedontheimpeller.Impellerstirringperformanceofthematerialofthepumpingandcreatevortex(Turbulence),whichproducesthefluidvelocityandfluidshear.Theformerleadstothereturnofallcontainers,mediatranslocation,preventingtheprecipitationofsolidsandproduceontheTubebundle(ifany)owashed,cutalargereturninthemicro-mixing,youcanbreaktheliquidbubblesorinsolubleDrops,resultinginuniform.Forthedoubleroleofdifferenttypesofimpellershavedifferentemphases.Pitchedbladeturbinesandhydrofoilimpeller(longthinbladepropeller)lowenergyconsumption,mainlytheaxialflow.Itsadvantageliesinaccessspeedofthefluid,commonlyusedinbatch(batch)productionmixingandsolidsuspension,thereisaworldisevenmoreimportant.Radialwheelhighenergyconsumption(suchascurvedleaves,trunkupright6-Rushtonturbine),resultinginahighpercentageofshear.Axialenergyround1/3Cut,2/3speed;Rushtonturbineonthecontrary,2/3consumedintheshear,commonlyusedinthegasdispersionandimmiscibleliquidemulsion.Themajorimpactofmixingonheattransferandthenatureofthematerial,mixingpowerandtransferfilmcoefficienthcrelationshipcanbeexpressedqualitativelythefollowingformula:(hcDT)/k=K(D2N/)(C/k)b(o/)cWhere:DTisthetankdiameter,Disimpellerdiameter,Nisspeed;C,k,andarethematerialspecificheat,thermalconductivity,densityandviscosity;oistheviscosityonthewall;K,a,bandcareexperimentalcoefficients.Themixerhasaseriesofhisusualvendors,sotheperformance(asitspowercoefficient,flowcoefficient)isalsoknownimpeller.Theproblemishowtocombinetheselectionofimpelleractualconditionstodeterminethegeometry,parameterssuchasspeedandtorque.Single-layerarrangementoftheimpellercanalsobemulti-layercombinationofimpellerpumpingdownwarddirectioncanalsobeup.Intechnologydesign,peopleoftenrefertoanexistingplantorlaboratorydataweresimilartozoominorout.2forliquid-liquidmixingandsolidsuspensionmaywishtoassumethatTQ(equivalentvolumeoftherequiredunitsoftorque,TQPVol.eq)asaconstantvalue,asthebasicparameters.Correctionfactorrequiredforitssmall,andthereforemoreaccurate,andcanthusdirectlythesizeoftheselectedgear(forgasdispersionissues,moreoftenamplifythepowerdemandasthebasicparameters).Figure1isapitchedbladeturbines,thematerialis1000cPviscositywhenthetorquebetweenthevolumeoftwoschematicdiagramoftheequivalentvolumeVol.eqequaltotheactualvolumeofmaterialthanthedensitymultipliedbySg(materialdensityandwaterdensityRatio,dimensionless),inunitsofUSgal,1USgal=31785L,torqueTQtolbinasaunit,1lb=01113Nm.Thislinearrelationshipcanalsobealist,asshowninTable1.Becauseofdifferentspeedsmadebydifferentchoices,actuallyintroducedtheconceptofpower.Intheory,thetorqueandpowerbythetwomethodstheresultsobtainedshouldbethesame.Mixingpowerconsumptionofthefollowingformula:P=NpSgN3D5/(6.12107)Where:Pispower(inhorsepowerhp,1hp=0.7457kW),NPisthepowerfactor(dimensionless),Sgisthespecificdensity(dimensionless),Nisimpellerspeed(rPmin)andDImpellerDiameter(infeetft,1ft=0.3048m).Npwiththeimpellerchanges,foragivenimpellertype,lowviscosity,abaffleofthecontainertoaconstant.Bafflestopreventvortex(swirl),locatedalmostallofthemixingbaffle.SmallTipAngleofthehydrofoilimpeller(longthinbladepropeller),Np=013;andthehighbladeRushtonimpeller,NpuptoPowerequationcanberesolvedintotwoparts:P=KN3D5=(K1ND3)(K2N2D2)Where:(ND3)reflectsthepumpingenergy;(N2D2)reflectingthecut.TiptangentialvelocityTipspeed=DN,andshearrelated.GeneraldesignprocedureGeneraldesignprocedureshowninFigure2.Figure5stepsare:1)TheuserequipmentaccordingtotheexistingD/DT(wheeldiameter/tankdiameter)values,andthemixingtime,mixingdegreerequirements,severaldifferentspeedsselectedtorqueorpowerrequirements.Amongthem,themixingisaffectedbymaterialviscositydifference,theproportionofpoor,ifnon-Newtonianfluidandotherfactors.Wecangiveaclassificationmethod(suchas:mild,moderate,severe,strong;or2,3,4Etc.),whichisafuzzyconcept.2)selectedtoinstallareasonableheightoftheimpeller,combiningequipment,itisestimatedtheapproximateshaftlength.3)areasonableestimateofthemotorpower.4)RefertoFactoryforperformance,suchastheimpellerpowerconsumption,speedreducer,theoutputshaft,frame,etc.,selectedtomeettherequirementsoftheformerthreeblender.5)andthentiptangentialspeedinaccordancewiththeconditions,determinethemostappropriatespeed,tooptimizethedesign,accordingtotheidentifiedconditionstocomputerprogramforpowerandstrengthoftheshaftsuchfactorsascheckingandanalysis.DesignExamples2.1CalculationofbasicparametersForapitchedbladeturbines,canbecalculatedwithfollowing:StepOne:SelecttheimpellerspeedN,suchas45,56rPmin;thesecondstep:CalculatetheReynoldsnumberofthecontainer.NRE=50V2P3NSg/,Where:Visthevolumebatchesofmaterials,USgals;Sgisthespecificdensity;istheviscosity,cP.StepThree:IfNRE15000,thefollowingcalculation,TQ=01084VSg,where:TQtotherequiredtorque,lbin.IfNRE15000,进行以下计算,TQ=01084VSg,其中:TQ为所要求的扭矩,lbin。如NRE15000,TQ=0.78Sg0.61V0.740.39PN0.39第四步:按不同的N重复计算,将计算结果列表。混合时间计算:先算雷诺数NRE为1550ND2Sg/,其中:N为叶轮转速,rPmin;D为叶轮直径,ft;Sg为比密度;为动力粘度,cP。混合雷诺数NB和容器雷诺数关系如图3所示。混合雷诺数NB定义如下NB=BT(TQ/Vol.eq)1P2/V1P3其中:BT为混合时间,min;V为批次物料容积,gals;(TQ/Vol.eq)为当量容积扭矩,1bin/gal,TQ/Vol.eq为63000HPP(NVSg),其中:HP=叶轮功耗,hp。验算:BT为NBN1P2V5P6