不均匀混合组分规整填料塔的发展

ISSN00405795,TheoreticalFoundationsofChemicalEngineering,2010,Vol.44,No.6,pp.869–876.©PleiadesPublishing,Ltd.,2010.OriginalRussianText©A.N.Pavlenko,V.E.Zhukov,N.I.Pecherkin,V.Yu.Chekhovich,S.Sunder,P.Houghton,2010,publishedinTeoreticheskieOsnovyKhimicheskoiTekhnologii,2010,Vol.44,No.6,pp.651–659.869INTRODUCTIONAccordingtopreviousstudiesintotheoperationofindustrialdistillationcolumnswithregularorstructuredpacking,theefficiencyofseparationcanoftendecreasewithanincreaseinthecolumndiameter,reducingtherecoveryandpurityofthefinalproduct.Thefundamentalcausesofareductionintheseparationefficiencyofthecolumnarethoughttoberelatedtothetransversemaldistributionofthelocalflowratesofthephasesandlongitudinalmixing.Thesephenomenarelatetothevaporandliquidflowsinsidethepacking,andtheyleadtodeviationsoftherecoveryandpurityofaproductfromthevaluescalculatedfortheidealconditionsofuniformdistribution.Therearemanycausesofnonuniformflowswithinthestructuredpacking.Thefactorthathasreceivedthemostattentionistheproperdesignandinstallationofdevicesusedforliquidandvapordistribution.Onemechanismthatisnotoftendiscussedisrelatedtothefactthatalldistillationcolumnsarecolderatthetop,whichcanleadtoasituationwherethevapordensityishigheratthetopofthecolumnthanitisatthebottom.Thisisapotentiallyunstablesituationinthelimitofalowvaporflowrate,anditcanleadtomaldistributionathighervaporratesasdiscussedfurtherbelow.Therehavebeenanumberofexperimentalstudiespublished,whichmeasureflowdistributionoverthecrosssectionofalaboratoryscalecolumnwithstructuredpacking.Themostcommontechniqueusedfortheinvestigationofmaldistributionisthemethodofliquidaccumulationunderpackingbycollectors[1–4].ApplicationofXraycomputertomographyandgammaraytomographytostudyingaflowinpackingswithcatalystsandstructuredpackingisknown[5,6].Thesemethodsfocusontheliquidflowrateandaccumulationwithinthepacking,buttheydonotgiveanyinformationonlocalcompositions.Thisworkinvestigatestheformationoflargescalemaldistributionofthemixturecompositioninsidethestructuredpackingofadistillationcolumn.Thedistributionsofthemixturecompositionweredeterminedbymeasuringthetemperaturefieldsindifferentcrosssectionsthroughoutthepackingheight.TheobjectiveofthepresentstudyistoexperimentallyinvestigatethemaldistributionofthecompositionoftheFreonmixturebeingseparatedinadistillationcolumnwithstructuredpacking.METHODSOFINVESTIGATIONExperimentswerecarriedoutinalargescaleseparationsetup.Thissetupisdescribedindetailin[3].Acolumnwithadiameterof0.6mwasfilledwithstructuredaluminumpackingwithaspecificsurfaceareaof500m2/m3.Thepackingconsistedof11layerswithatotalheightof2.3m.Thedirectionofcorrugatedsheetsineachsubsequentlayerwas90°relativetothedirectionofsheetsinthepreviouslayer.ExperimentswerecarriedoutusingtheFreonmixtureofR114andR21withacountercurrentflowoftheliquidandthevapor.Theratioofthemolarflowratesoftheliquidandthevaporwasequaltounity(totalreflux).Thepackingwasuniformlyirrigatedbyatroughtypeliquiddistributorwithahighdrippointdensity.DevelopmentofMixtureCompositionMaldistributioninaDistillationColumnwithStructuredPackingA.N.Pavlenkoa,V.E.Zhukova,N.I.Pecherkina,V.Yu.Chekhovicha,S.Sunderb,andP.HoughtonbaKutateladzeInstituteofThermophysics,SiberianBranch,RussianAcademyofSciences,pr.AkademikaLavrent’eva1,Novosibirsk,630090RussiabAirProducts,Inc.,Allentown,Pa.,USAemail:[e-mail]29,2009Abstract—ThedistributionofthecompositionofamixtureofFreonsR114andR21overthecrosssectionofadistillationcolumnfilledwithstructuredpackingisexperimentallystudied.ResultsontheefficiencyofFreonmixtureseparation,thepressuredropinthepacking,andthedistributionofthelocalconcentrationofthelowboilingcomponentthroughoutthecrosssectionandheightofthestructuredpackingarepresented.Thevaporphaseloadfactorwasvariedoverawiderangeuptohydraulicflooding.Accordingtotheexperimentalresults,thelargescalemaldistributionofthemixturecompositionoccursinsidethepackingoverthecolumncrosssection,eventhoughtheoverallseparationperformanceofthecolumnisexcellent.Maldistributionisobservedthroughoutthetotalheightofthecolumn.Thelocationofthelargezonesofmaldistributionsignificantlydependsontheliquidandvaporflowrates.DOI:10.1134/S0040579510060060870JOURNALOFCTHEORETICALFOUNDATIONSOFCHEMICALENGINEERINGVol.44No.62010PAVLENKOetal.Themaldistributionofthelocaldensityoftheliquidflowratewasmeasuredatthepackingoutletbyaspeciallowpressureflowmetermountedonatwocoordinatedevicethatwasprogrammedtoscanthecolumncrosssection[7].Aliquidsamplewascollectedatthesametimetheflowwasmeasured,andthesamplefromthisdevicewassenttoachromatographtodeterminethecompositionofthebinarymixture.Accordingtomeasurementsatthepackingoutlet,therearesignificantmaldistributionsofthelocalliquidflowrateandthemixturecompositionoverthecrosssectionofthecolumn[4].Tomeasurethemaldistributionofthelocalmixturecompositionoverthecrosssectionofpacking,amethodbasedonthemeasurementoftemperaturefieldswasalsoused.Temperaturesensorsweremountedinsidethepackinginthreecrosssectionsatdifferentlocati