毕业设计翻译.docx

毕业设计翻译.docx

《毕业设计翻译.docx》由会员分享，可在线阅读，更多相关《毕业设计翻译.docx（15页珍藏版）》请在冰豆网上搜索。

毕业设计翻译

Axialmixingandmasstransfercharacteristicsofpulsedextractioncolumnwithdiscsanddoughnuts

Abstract:

Theaxialmixingisakeyfactorfordesignandscalingupofthepulsedextractioncolumnwhichhasstronginfluenceonthemasstransferperformancesofthepulsedextractioncolumnwithdiscsanddoughnuts.Asteady-stateconcentrationprofilemeasurementwasusedtoevaluatethemasstransferandaxialmixingcoefficientsforthenitricacid/water/30%TRPO（inkerosene）systeminthepulsedextractioncolumnwiththediameterof38mmontheconditionoftheTRPO-kerosenesolutionasthecontinuousphaseandtheflowratioof1∶1.ExperimentalresultsindicatethatEyevaluatedbytheexperimentsisingoodagreementwiththatgivenbyBurratti’scorrelation;theaxialmixingisfarsmallerforthecontinuousphasethanthatforthedispersedphase.HowevertheempiricalcorrelationforHOXisonlygivenbasedonthepresentdata.

Keywords:

pulsedextractioncolumn;axialdiffusionmodel;masstransfer;steady-stateconcentrationprofile

1Introduction

Liquid-liquidextractionhasbeenregardedasoneofthemostusefulseparationprocess.Inrecentyears,anewtypeofextractioncolumn,calledthediscsanddoughnutspulsedextractioncolumn,hasbeendevelopedandextensivelyappliedtoreprocessthespentnuclearfuelinFranceandJapan[1,2].Theextractioncolumnhasshownthefollowingadvantages:

highefficiency,perfectfloodingthroughputs,norotational

parts,easyclearanceandsoon.

Theconclusionthattheaxialmixingofthetwophasescountercurrentflowleadstothedecreasingofthemasstransferefficiency[3]hasbeensummarizedbyLUO[4]forthepulsedsieve-plateextractioncolumn.

However,theknowledgeconcerningthehydrodynamicsandmasstransferperformanceofthepulsedextractionwithdiscsanddoughnutsisrarelyreported.OnlytheaxialmixingcharacteristicsfortheextractioncolumnhavebeeninvestigatedandsummarizedinTable1.

InTable1,thecorrelationsoftheaxialdispersioncoefficientofcontinuousphaseinthecolumnaregivenbyZAHARIEVAandMASBERRAT[5],NABLIandGUIRAUD[6],OH[7],BURATTI[8]respectively,bymeansofthenumericalsimulation,andtheconclusionsaredrawnasfollows:

1）EcincreaseswiththeincreaseoftheplatespacingH.

2）TheeffectofDonEccanbeneglected,asdescribedbyBURRATTI.

3）PackingfreeareaαisindependentofEc.Itisshownthatatthesamecolumnparametersandoperationalparameters,EcpredictedbyBURRATTI’scorrelationissmallerthanthatbyOHandNABLI’s

correlations.FromTable1,itiseasilyobservedthatEcincreaseswiththeincreaseofthepulsedparameters,namely,Aandf.

ThedispersedphaseaxialmixingcharacteristicswasonlyreportedbyBARDIN-MONNIRandGUIRAUD[9]forpulsedextractioncolumnwithdiscsanddoughnuts.Thedispersedphaseaxialmixingcoefficient,Ed,wassimulatedwithcomputationalfluiddynamicsandLagrangiansimulations,andtheresultshowedtheaxialmixingwasfarlessimportant（aboutonetenth）forthecontinuousphasethanforthe

dispersedphase,butthecontinuousphaseaxialmixingwaslargerthantheaxialmixingofasingledrop.

InordertoprovidethesufficientknowledgeofthedesignandscalingupwhenthepulsedextractioncolumnwithdiscsanddoughnutsisusedinthenucleartheplatespacingontheaxialmixingandmassindustryofChina,theaxialmixingmodelcombinedwiththesteady-stateconcentrationprofilesmethodisusedto

Table1Reportedresultsofaxialmixingcharacteristicsinpulsedextractioncolumnswithdiscsanddoughnuts

evaluatetheeffectofthepulsationintensionandtransfercharacteristicsforthepulsedextractioncolumnwithdiscsanddoughnutsatthephaseratioR=1.

2Experimental

2.1Experimentalset-upandsystem

Theexperimentalapparatus,asshowninFig.1,consistedoffourparts:

adiscsanddoughnutscolumn

（1）,thepneumaticallypulsedsystem（20-22）,thefeedinganddischargingsystemofthetwophases（9-19）,

andthemeasurementsystem（5-8）.Thecolumn,whichwasmadeofaverticalcylindricalglasspipe,containedaseriesofdiscsanddoughnutsalternatelyarrangedandmaintainedbythebracesofconstantlength,asshowninFig.2,andFig.3.TheparametersofthecolumnandtheplateusedintheexperimentsareshowninTable2.

Table2Structureparametersofcolumn

Thereweresixpairsofsamplerarrangedalongthewallofcolumn,asshowninFig.1（23）.Thesamplingtubesineachpair,whichwithdrawnthesamplesforthecontinuousphaseandthedispersedphaserespectivelyatthesametime,werefilledwiththehydrophilicfibreandthelipophilicfibrerespectivelytoavoidthemixingoftwophases.Theexperimentalmaterialsusedintheexperimentswerenitricacidsolutionfortheaqueousphaseand

Fig.1Schematicdiagramofpulsedext