文献翻译-精馏过程的节能技术

附录Energy-savingtechnologyofdistillationprocessAbstract:Distillationisachemical,petrochemical,pharmaceuticalandotherimportantunitoperationinprocess;thispaperfocusesonenergy-efficientdistillationprocess.Heatfromthedistillationprocessfulluse;improvetheseparationefficiencyofdistillationsystems,improveproductrecoverytoachievelowerenergyconsumption;reducetheenergyneedsofthedistillationprocessandthestrengtheningofmanagementaspects,discussesindetailtheenergy-savingtechnologyofdistillationprocess.Keywords:distillation;energy1IntroductionInindustrialproduction,petrochemicalindustry,thelargestproportionofenergyconsumption,whileenergyconsumptioninthepetrochemicalindustryforthegreatestseparationoperation,amongwhichtheenergyconsumptionofdistillationthefirstplace.Distillationprocessisacomplexheatandmasstransferprocess,asfollows:theprocessofmulti-variable,controlledvariableandmorecontrollablevariablesaremany;processandmechanismofcomplexdynamic.First,withtherapiddevelopmentofpetrochemicalindustry,distillationismoreandmorewidely,increasingseparationofthecomponentsofmaterials,separationoftheproductpurityrequirementsarebeingimproved,butpeoplealsodonotwanttoconsumetoomuchenergy,whichthecontrolofthedistillationprocesstomakearequest.Secondly,asachemicalproductionprocessofthemostwidelyseparated,largeenergy-consumingdistillationisachemicalunitoperation.Intheactualproductioninordertoensurequalifiedproducts,distillationunitoperationisoftenconservative,methodsofoperationandoperatingparametersareoftenlessreasonable.Inaddition,becausetheenergyconsumedmostofthedistillationprocessisnotusedforcomponentseparation,butwastakenawaybycoolingwaterorseparatecomponents.Therefore,thedistillationprocessisgreatpotentialforenergysavingandrationaluseofthermaldistillationprocessitself,thewholeprocesscanreducetheenergydemand,reduceenergywasteofenergyisalsoveryeffectiveobvious.Accordingtostatistics,theenergyconsumptionofdistillationprocessintheUnitedStatesaccountedfor3%ofthenationalenergyconsumption,savingfrom10%iftheannualsavingsof$500,000,000.Chinasconsumptionofcrudeoilrefineryofitsrefiningcapacityof8%to10%,muchofitconsumedinthedistillationprocess.Thus,inthecaseofthecurrentenergyshortage,savingoftheprocessofdistillationisveryimportant.Forexample,theUnitedStatesinPuertoRicoBartelsaromaticsunit8ofdistillationcolumnoptimizationenergyontheoperation,annualsavingsof$3,100,000.Energy-efficientdistillationprocessbasicallyfromthefollowingaspects:(1)fullutilizationofheatdistillationprocess;(2)increasetheseparationefficiencyofdistillationsystems,improveproductrecoverytoachievelowerenergyconsumption;(3)reductionofdistillationprocessontheenergyneeds;(4)tostrengthenmanagement.2,thefullutilizationofthedistillationprocessheat2.1strengthenedtoimprovethethermalinsulationcolduseInthedistillationequipmentusedinthedistillationcolumnandthemainheatexchanger,inadditiontoavarietyofchannels,thesedevicesaremostlymadeofmetal,iseasiertoheatconduction,combinedwiththeimpactofambienttemperature,iftakentoitscoldinsulationmeasurescangreatlyreducetheequipmentandtheroleofheattransferbetweentheenvironment,soastoachievethepurposeofsavingenergy.Strengthentherecoiledandcondenserheattransfertemperaturedifferenceinheattransfercandecrease,duetoreducedtemperaturedifferencecanmaketopcoolanttemperaturerises,theheatingtemperaturedroptowerreactor.Thisincludesenhancingtheheattransferareaandtheuseofaircoolersorevaporativecoolersinsteadofwatercoolersandothermethods.2.2Thehigh-temperaturematerials,sensibleheatandlatentheatutilizationHigh-temperaturematerialsfromthedistillationcolumnitselfiscarryingoutalotofheat,thispartoftheheatenergyforrecyclingisalsoa.Suchas:(1)hightemperaturedistillationtowermaterialsrecoveredlatentheatofsteam,thetopcondenserforthesteamgenerator.Operatingpressureof32KPa,suchascrudestyrenetower,thetopmaterialcanbeusedforheatingsteamintothereactorforethylbenzenedehydrogenation.Thisarrangementallowsenergypertonofstyreneproducts(2)thetopofthetower,towerreactormaterialsandrawmaterialsforheattransferfluidthroughthetopmaterialtotheheatingofrawmaterials.Thiswillnotonlytakeadvantageofthetower,towerreactormaterials,wasteheat,butcanalsoreducetheoverheadcondensercoolingcapacityusage.2.3UsingpinchtechnologyforheatexchangernetworkoptimizationForachemicalsystem,whenanumberofsharesofheatandcoldmorethansharesoftheheatexchanger,theheatcanbecombinedintooneallhotcompositecurve,allcombinedintoacoldcompositecurve,andthenthetwotogethermeansthatAtemperatureenthalpydiagram,thepinchpointistheenthalpydiagraminthetemperatureofahotandcoldcompositecurvescoincideatapointwhentheheattransferwithinthesystemlimitofcoincidencepointsofthetemperaturedifferenceiszero,thepointisthepinchpoint.Temperatureisbelowzeroatthepinchpoint,youneedaninfiniteheattransferarea,canbedeterminedbytechnicalandeconomicevaluationofasystemofminimumtemperaturedifference-pinchpointtemperaturedifference,sopinchpointcanbedefinedashotandcoldtemperaturescombinedonlinewheretheminimumtemperaturedifference.Inthesynthesisofheatexchangernetworksusingpinchtechnologytoconsideravarietyoflogisticsmatch,heatexchangernetworkcanmakeoptimaluseoftheheat.3,theseparationdistillationsystemtoimproveefficiencyandproductrecoveryMorethan3.1effectdistillationtechnologythegeneralmulti-effectdistillationprocessshowninFigure1.Multi-effectdistillationfromtheN-paralleloperationofadistillationcolumncomposition,asshowninFigureloperatingefficiencybyreducingthepressurefromlefttoright.Tophighpressureinfrontofthetowerbehindthelowpressuresteamasthebottomrecoiledheatingmedium,inwhichthecondensation.Iftwoadjacenttowerrecoiledcondenserandtheheatloadbalance,onlythefirsttowertobeheatedrecoiledsteam,thelasttowerofthecondensercoolingmediumneeds.ByN-effectdistillation,andthenboilingthesteamrequiredforheatingcanbereducedtotheoriginalsingle-effectheatrequiredforsteamdistillationI/Norso.Practiceshowsthattheheatrequiredfordistillationoftwoeffectivesingle-effectdistillationsandcomparisoncanbereducedby30to40%.Fig.1Multi-effectdistillationtechnology3.2Thelow-temperatureheatpumpdistillationtechnologywhenusingarefrigerantcondensercoolingtoweriscalledlow-temperaturedistillation.Cryogenicdistillationatalowerpressure.Andbecausethelargertherelativevolatilityatlowtemperature,refluxratiocanbesmallertoreducethecondenserandrecoiledheatload.Single-effectdistillationandheatpumppumpingheatfromthecondensertotherecoiledofthelow-temperaturedistillation,knownastheheatpumpdistillation.Heatpumpdistillationcanreduceenergyconsumption.Totopsteamcondensationheatreleasedwhentherecoiledprovidestheheatsourceasthegasificationchamber,theuseoftheexpansionvalveandcompressortochangethetemperatureofcondensationorboiling.Figure2showsthemostsimpledistillationwithheatpump,inthetopcondenserandbottomrecoiledjointbetweentheclosedlooponanadditionalrefrigerant,refrigerantevaporatesinthetopcondenserabsorbsheat,andthenCompressedbythecompressor,coolingtowerkettlerecoiledandreleaseheat,andthenthethrottletothetopofthetowercondenservacuumevaporation.Soagain,keeptheheatpumpedfromthecondensertothelowtemperaturehightemperaturerecoiled.1.Distillationcolumn;2.Compressor;3.Recoiled;4.ThrottleFig.2Distillationheatpumptechnology3.3FullyThermallyCoupledDistillationColumnTechnologyFullyThermallyCoupledDistillationColumn60yearsofthe20thcenturysacomplexdistillationtechnology,mainlyfortheseparationofternarymixtures.Thetypeofthetowerhadbeenin1989,thefirstbytheGermancompanyBASFtoachieveindustrialization,ascomparedwithconventionaldistillationcolumnthermallycoupleddistillationcansaveenergyupto30%.Canuseafulltowerandadeputyinsteadoftwocompletedistillationtower,fulltowerfromtheliquidphaseleadstoanassociateTatalogisticsdirectlyasthetopoftheliquidreflux,gaslogisticsdirectlyleadstoanendasViceTataGasreturntoavoidtheuseofcondensersandvicetowerrecoiled,toachievethecouplingofheat,calledthermalcouplingdistillation.Thermocoupledistillationinthermodynamicsistheidealsystemarchitecturecansaveequipmentinvestment,butalsosaveenergy.Calculationsshowthatthermalcouplingdistillationtowerthanthetwoconventionaldistillationscansaveenergy30%.JapansSumitomoHeavyIndustriesLtd.andKruppUhdecompletedtheindustrializationofthermallycoupleddistillationtower,crudepurificationcompanyintheUnitedStatesUOPdeviceheptanesdistillationcolumnusingaverticalpartition(thermallycoupleddistillationcolumna).Itusesmultiplefeedtechnologies,andincludestheabsorptionprocess.Thedevelopmenttrendfromtherecentyears,thermallycoupleddistillationofgoodprospectsforindustrialapplications.AgrawalandFidkowskithermodynamicefficiencyfromthepointofview,theidealoftheseparationofthreeYuansaturatedliquidthermallycoupleddistillationsequencewiththeconventionaldifferences.Schultzandputforwardanumberofthermallycoupleddistillationusedrulesofthumbthattheselectionofthermallycoupleddistillationare:thecontentofthefeedcomponentsaremoremiddleofthelightkeycomponentandintermediatecomponentandtherelativevolatilitybetweencomponentsandheavykeycomponentsoftherelativevolatilitybetweentheclose.LuXiangHong,Luenxirigorousdistillationmodelcalculationstosimulatetheseparationofmixtureofthreecomponentsthermallycoupleddistillationcolumnsandsequencesoftheenergyconsumptionofconventionalsimpledistillation,thermallycoupleddistillationcolumnapplicationoftheprecondition,andtorecommendthermallycoupleddistillationprincipleofselection:(1)WhentheseparationindexESI1whennotinusethermallycoupleddistillationprogram.(4)Iftheconventionaldistillationtoweroperatingpressuredifferencelarger,andisnotusedthermallycoupleddistillationprogram.3.4distillationstowerinternalheatintegrationHeatintegrationwithinthedistillationcolumn(InternallyHeatIntegratedDistillationColumn,referredtoasHIDiC),refertothesamesectionofthetoweritselfandthestrippingsectionofdistillationforheatintegration.Itisthroughthedistillationcolumnrectifyingsectionandstrippingsectionoftheheatintegrateddistillationcolumntoachievethenon-operationofcondenserandrecoiled,thusgreatlyreducingtheenergyconsumptioncomparedwithconventionaldistillationenergysavingsupto3060%;Thisisthebiggesteverknownenergy,themostadvancedtypeofdistillationcolumn.Theideawasfirstinthe20thcentury,60yearsmountainFreshwaterproposed,andthentherehavebeenscholarshavepublishedresearchresults.JapanesescholarM.Nakaiwaotherexperimentalstudiesonthebasisofcomplete,wasadoptedin2000inthetrialofthetower,thecurrentismovinginthedirectionofindustrializationandprogress.Heatintegrationwithinthetraditionaldistillationtowerandhasaverybigdifference:thetraditionaldistillationtoweressentialkettletopcondenserandrecoiledarenolongerneeded,theoriginalisdividedintoadistillationcolumndistillationandstrippingtwotowers,distillationtowerplacedinthestrippingrate.HIDiCtheenergyconservationprinciplecanbeMcCabe-Thiele(MT)Chartinterpretation.Figure4isaconventionaldistillationtowerMTmap,therectifyingsectionandstrippingsectionoperatinglineforthetwolines.Thefigure,XDisthemolefractionoftopproductcomposition,XBisthemolefractionofthetowerreactorproductcomposition,Xisthemolefractionoffeedcomposition,x,y,respectivelyfvolatilecomponentsinthecompositionofliquidandgasphasemolefraction.Masstransferdrivingforcefortheoperatinglineandequilibriumlinedistancebetweenitsnon-equivalentdistributionalongthetower,thefeedboardattheminimum,tothegradualincreaseinbothendsofthetower.Thisisamajorcauseofahighdegreeofirreversibility,theoperatinglineandequilibriumlinethegreatertheverticaldistancebetweentheeffectiveenergylosseswillbe.TheabolitionofthecondenserandHIDiCtowerrecoiled,makingoperatinglineandequilibriumlineintoashapesimilartothecurveshowninFigure5.ThusHIDiCtowerhasahighthermodynamicefficiency.3.5usingthenewhighefficiencyseparationtechnologySeparationareachievedthroughthetowerequipment.Transformationoftheconventionalplatetower,high-efficiency-orientedscreen,butcanreduceenergyconsumptionandincreaseproductioncapacity.3.5.1EfficientguidedsievetrayEfficientguidedsievetrayisincludedintheBeijingUniversityofChemicalTechnology,includingavarietyofsieveplatetraydepthanddetailedstudybasedonasimplestructuretoplayasievetray,thecharacteristicsoflowcost,toovercometheleakageofhighandlowefficiencydisadvantages,andthroughin-depthstudyofvariousplates,andcomprehensivecomparisonswithTrayscienceofhydrodynamicsandmasstransferresearchanddevelopmentofanewandefficienttray,anditsworkingprincipleisshowninFigure6.Highefficiency-orientedguidedsievetrayisopenedalargemeshsieveandasmallpartofthepilotholethroughthesieveplateandtheliquidgasinthewrongtowerflowthroughtheliquidlayerverticalrise,drivenbythegasalongthesievetraylevelforward,themomentumtransfertotheTowerboardlevelflowofliquid,soastopromoteuniformandstableliquidinthetrayplateforward,toovercomethegapbetweentheoriginaltowerpanelandliquidback-mixingliquid,increasetheproductioncapacityandtheboardefficiencytosolvetheblocktower,nightpanandotherissues.Inaddition,theboardinthetraditionaltower,duetosurfacegradient,upstreamoftheplatethereisalwaysanon-activearea;flowinthisregioncannotrisethroughthebubblingliquidlayer.Experimentaldetermination,non-activationoftheareasofthecross-sectionalareaofthetowerabout1/3.Efficientsieveintheflowdirectionincreasedtheconvexentrancerampsintothebubble-likefacilitatortopromotetheliquidintothetraycangenerateabubble,bringingagoodgas-liquidcontactandmasstransfer.Efficiency-orientedsievehasthefollowingcharacteristics:(1)productioncapacity;(2)highefficiency;(3)pressuredrop;(4)anti-blockingcapability;(5)simplestructure,lowcost3.5.3ThenewhighefficiencypackingPackingtowerpackingisthemostimportantmasstransferwithintheparts;itsperformancedependsonthefillersurfacethewetbodyoftheextentanddistributionofgas-liquidtwo-phaseflowuniformity.(1)newandefficientstructuredpackingNewhighefficiencymetalstructuredpackingincludingpackingandmetalmeshpackingtwocategories,initsphysicalandchemicaltreatmentprocess,fillingtheseparationefficiencygreatlyimproved.Mainadvantagesare:(1)thehighnumberoftheoreticalplates,flux,andpressureisreduced.(2)low-loadperformance,numberoftheoreticalplatesdecreasedwiththeincreasedgasload,nolowloadlimit.(3)Amplificationeffectisnotobvious.(4)Forvacuumdistillation,tomeetthesophisticated,large-scale,high-vacuumdistillationunitrequirements,difficultisolatesDepartment,heat-sensitivematerialsofhighpurityproductlinesandprovideadistillationoffavorableconditions.(2)newhighefficiencyrandompackingMetalPallringpacking40yearsofthe20thcenturyGermanBASFRanchingringpackinginthedevelopmentofthebasis.Itusesredsheetmetalrolledintotheringoutofthewallwith2rowsoffenestratewithintheSenseleaves,eachrowof5windowsbendsleaftongueringspointingintotheringwithaheart,almostinthecenterrelativetotake,F2layeronastaggeredpositionoffenestrate,thegeneralopeningoftheringareaofthetotalareaofabout35%.Becausemanyoftheringwallsopenedwindows,sofilllayerofgasandliquiddistributionandmasstransferperformancelaXiringhasgreatlyimproved.(3)Ladderringpacking70intheearly20thcenturybytheBritishmassvalueofthecompanydevelopedatechnologytoimprovethewholeringpacking.Suchfillersreducetheheightofring,andthetwosideoftheringincreasestaperedendflange,itsperformancecomparedwithPallringpackingmadegreaterprogress.Inthesamedensityoftheliquidspray,itspan-pointvelocityincreasedmorepallring10to20%;inthesamegasvelocity,thepressuredroplowerthanthePallring30to40%.(4)FillermetalringInterlocksthisisAmerica,Norton(Norton)haspioneeredtheresearchanddevelopmentofanewtypeoffiller,theBritishdomesticTroyCoxreferredtoasfiller.Thisfillerskillfullyandsaddleringfeaturestwotypesofpackingconsolidatedintoone,makingitboththecharacteristicsoftheringpackingflux,therearesaddle-shapeddistributionofgoodperformancecharacteristicsofliquidfiller,powderfillingcompoundtobecomeleader.Newhighfilldozensofcompanieshavebeenappliedtowersaremadeexpansion,energyconservation,energy,greatlyimprovingeconomicresults.4,reducingtheenergyneedsofdistillationprocessDistillationprocesstoreducetheneedforenergyisafundamentalenergy-savingmethod,themainseparationsequenceshouldconsidertheselectionandoptimizationofoperatingconditions.4.1Optimizationoftheorderofmulti-towerdistillationUseofN-componentdistillationcolumnserieswillbeseparatedfromthetowerstobeN-1,andtheordercanhaveavarietyofitsprograms,thenumberofitsprogramsavailableexpressionS=2(m-1)!/M!(M-1)!That(wheremisgroupscores).Forexample,therearethreecomponentsarrangedintwoprograms,thereare42six-componentprograms,selectamajorimpactonenergyconsumptionwillbegoodorbad.Separationsequenceinthechoice,youcanrefertothefollowingprinciples:(1)shouldbekeycomponentsoftherelativevolatilityoftheclosestto1,themostdifficultonthefinalseparation,thatisafteralltheothercomponentsareseparatedout;(2)Accordingtothesizeofgas-liquidequilibriumconstantofsort,thelightcomponentsremovedonebyone,thatistotaketheorderprocess:(3)shouldfirstbedividedintothenumberofmoleculesclosetothemixtureofthetwo-stream;(4)highrequirementsforrecoveryseparationshouldbeplacedattheend;(5)likelytocausecorrosionorcokingsystemcomponentsshouldberemovedfirstinordertoreducethematerialrequirementsofthefollow-updeviceorstabilityoperation;(6)Forverydifferentcomponentsofthemixtureboilingpoint,andifSomecomponentsneedtobeseparatedundertheconditionsoffreezing,thesystemshouldbemadeintofrozenorchilledhighersystemleveltominimizethegroupscores.4.2changetheconditionsandmethods4.2.1choosesuitablerefluxratioRefluxratioaresmaller,thesmallerthenetpowerconsumption.Therefore,weshould,wherepossible,reduceoperatingundertheconditionsofrefluxratioR.Columndiameterwillincreasewithincreasingrefluxratio.Therefore,theoptimalrefluxratioreflectsthecostofequipmentandthebestbalancebetweenoperatingcosts.Accordingtoreports,had70differenthydrocarbondistillationstatisticalcalculations,theoptimalrefluxratioRareminimumrefluxratioofbetween1.11to1.24times,optusuallyintheDepartmentofisolateswithhigherrelativevolatilityorseparationrequirementsthecaseisnotveryhigh,onthecontrary,iftherelativevolatilityofpropertylinesorseparatedemandingclosetol,thenusedRtobesignificantlyopthigherthanR.Ingeneral,ifRoptoperating,thetotalcostofmostofthecostofminoptheatingsteam,about70%,whilethecostofcoolingwateronlyafewpercent.However,whenthecon