文献翻译-分批冲孔模板精馏塔的操控

英文翻译ChineseJofChemEng，9(2)141144(2001)OperationofaBatchStrippingDistillationColumnxuSonglin(许松林)，JoseEspinosab，HectorESalomonebandOscarAIribarrenbaNationalEngineeringResearchCenterforDistillationTechnology，TianjinUniversity,Tianjin300072，ChinabInstituteforDevelopmentandDesignINGAR,Conicet，SantaFe，ArgentinaAbstractAstrippingbatchdistillationcolumnispreferredwhentheamountofthelightcomponentinthefeedissmallandtheproductsaretoberecoveredathighpurityTheoperationmodesofabatchstrippingarebelievedtobethesameasthoseofarectifierHoweverthecontrolsystemofastripperisdifferentInthispaper，weexplorethreedifferentcontrolmethodswithHysys(HyprotechLtd1997)forabatchstripperThemaindifferenceisthecontrolschemeforreboilerliquidlevel：(a)controlledbyrefluxflow；(b)controlledbyreboilerheatduty；(c)controlledbybottomproductflowThemaincharacteristicsofoperatingabatchstripperwithdifferentcontrolschemearepresentedinthispaperGuidelinesaxeprovidedforthestartupofabatchstripper，theeffectsofsomecontroltuningparametersonthecolumnperformancearediscussedKeywordsbatchstrippercontrolOperation1INTRODUCTONBatchprocessisbecomingmorepopularaschemicalprocessindustriesmovetowardmanufacturingfineandspecialtychemicals，whereflexibilityisakeyissueduetothefrequentchangeofproductdemandBatchdistillationcolumnsareinherentlyflexible，asasingle1columncallseparatemanydifferentcomponentsfromamulticomponentfeedThustheuseofbatchdistillationisbecomingmoreimportantfortheseperationandpurificationofhighvaluechemicalsinmanychemical,food，andpharmaceuticalindustriesTraditionallythemostpopularkindofbatchdistillationcolumnistheso-caledrectilyingcolumnwhichhasalargereboiler，towhichalthefeedischargedandifferentproductsareremovedfromthetopTherearethreewaystooperatearectifyingcolumn2Theyare：(1)constantrefluxandvariabledistillatecomposition，(2)variablerefluxandconstantdistillatecompositionofkeycomponent，(3)optimalrefluxpolicywhichtradesof(1)and(2)andisbasedonthemostprofitableoperationBatchstrippingcolumnisopposedtoabatchrectifierIthasitsstoragevesselatthetopandtheproductsleavethecolumnatthebottomAstrippingbatchdistilationcolumnispreferredwhentheamountofthelightcomponentinthefeedissmallandtheproductsaretoberecoveredathighpurity4,5TheoperationmodesofabatchstrippingarebelievedtobethesameasthoseofarectifierHoweverthecontrolsystemofastripperisdifferentInthispaper，weexplorethreedifferentcontrolmethodswithHysys(HyprotechLtd1997)forabatchstripperThecontrolschemesareshowninFig1Themaindifferenceisthecontrolschemeforreboilerliquidlevel：(a)controlledbyrefluxflow，(b)controlledbyreboilerheatduty，(c)controledbybottomproductflowThemaincharactericsofoperatingabatchstripperwithdifferentcontrolschemearepresentedinthispaperGuidlinesareprovidedforthestartupandtheeffectofsoecontrolturningparametersonthecolumnperformancearediscussed.2EXPERIMENTALAPPARTUSFORTHESIMULATIONSTheexperimentalapparatusinthesimulationsisthesameforthethreecontrolschemesThestrippingcolumnhasareboiler，acondenserand15traysThevolumesofthereboilerandthecondenserare2m3and5m3，respectivelyThediameterofthecolumnis0.5mThefeedisthemixtureofmethanol(0.05)andethanol(095)(molefraction)Theliquidpercentlevelsetpointforthereboileris50andthemixturetakes80ofthewholevolumeofthecondenserAtthebeginning，thetraysaredrystartup，butthereboilerischargedwiththesamemixturetotheliquidlevelsetpointThespecificationofbottomproductethanolis0999Allthesimulatedexperimentalproceduresarethatthestripperisstarteduptillthespecificationoftheheavykeycompositionisreached，thenthebottomproductvalveisopenedsothattheproductleavesthecolumn，theproductvalveisshutdownwhentheproductcompositiondeclinestothespecification3RESULTSANDDISCUSSION31ControlreboilerHquidlevelbyrefluxflowInthiscontrolscheme【Fig1(a)】，thereboilerliquidpercentleveliscontrolledautomaticallybyrefluxflow，thereboilerheatinputandbottomproductflowarecontroledmanualyAtthebeginning，thereboilerheatinputissetfixedThereboilerliquidleveldeclinesasthelightcomponentisvaporizedWhichwillcauserefluxflowdownthereboilerautomaticallyThecontrolofthereboilerliquidlevelisreversibleSowhenthereboilerliquidlevelishigher，therewilbelessrefluxflowandviceversa.Whenthecompositionofheavykeycomponentgetstoitsspecification，thebottomproductflowvalveisopened；onceitdeclinestothespecification，thebottomproductflowvalveisshutdownmanualyInthiscase，whenethanolcorn-positionreaches0999，thebottomproductflowvalveisopened，whenethanlislessthan0999thebottomproductflowvalveisshutdownThedynamicprocessofthisoperationmodeisshowninFig2Thereisatimelagbetweenthereboilerliquidlevelandrefluxflow，especiallywhenthenumberofstagesislargeInordertogetastablereboilerliquidlevelcontrolduringthewholeoperation，twoaspectsshouldbeconsideredcarefully0neistouseanappropriaterefluxvalveIftherefluxvalveisoversized，thereboilerliquidlevelcontrollerwilgetmorerefluxflowtothereboilerthanthesetpointwhentheliquidleveldeclinesThentherefluxflowvalvewillbeclosedThismakesthereboilerliquidlevelfluctuatefrequentlyOnecaseisshowninFig3InthissituationtheheavykeycomponentcompositioninthebottomisunstableTheotheraspectisthatthetuningparameterofthereboilerliquidlevelshouldbechosenappropriatelywhenaproportionalonlybottomlevelcontrolerisemployedTheproportionalgainofthecontrolershouldbebetweenPK40and80Ifistoosmall，itisdifficulttogetastablereboilerliquidlevelPKcontro1Fig4showstherelationbetweenreboilerliquidpercentlevelandforthesamePKreboilerdutyFromFig4itisobviousthatifislessthan40theliquidpercentlevelinPKthereboilerisfarawayfromthesetpointlevel50Ifisbetween40and80，thePliquidlevelinthereboilerisnearthesetpoint32ControlreboilerliquidlevelbyreboilerheatinputInthiscontrolschemeFig1(b)】，thereboilerliquidleveliscontrolledbyreboilerdutyautomatically,refluxandbottomproductsflowarecontrolledmanuallyAtthebeginning，therefluxflowvalveisopenedtoafixedvalueReboilerliquidlevelincreases，whichwillcauseheatinputtothereboilerTheactionofthereboilerliquidlevelcontrolerisdirect，whichmeansthatthehigherthereboilerliquidlevel，themoretheheatinputtothereboilerandviceversaWhenthecompositionoftheheavykeycomponentinthereboilergetstoitsspecificationthebottomproductflowvalveisopenedmanulyWhentheheavykeycomponentcompositiondecreasesto0999，thevalvesforbottomproductandrefluxflowareshutdownmanuallyFig5showsthedynamicprocessofthisoperationmodeItisobviousthattheboilupmassflowandtheliquidlevelsofcondenserandreboilerarefluxedatthestartupoftheoperationThisisduetothedynamicresponsivenessofreboilerheatinputtotheliquidlevelcontroller33ControlreboilerHquidlevelbybottomproductflowThereboilerliquidleveliscontroledbybottomproductflowinthiscontrolschemeFig1(c)】ThisschemeissimilartothethirdcontrolmodeforarectifierinwhichthereboilratioisvariableInordertogetthebottomproductspecification，atotalreboilprocessshouldbeestablishedatthebeginningoftheoperationTheactionofthereboilerliquidlevelcontrollerisdirect，whichmeansthatthehighertheliquidlevel，themorethebottomproductflowandviceversaFigure6(b)showsthatatthestartupofthisoperation，theliquidlevelsinbothreboilerandcondenserareoscillated，sinceitisdifficulttomeettherequirementforthetotalreboilatthebeginningoftheoperation，fortherefluxflowandreboilerheatinputareoperatedmanually4CONCLUSIONThedynamicsimulationwithHysysfortheoperationofabatchstrippingdistillationcolumnindicatesthemaincharactericsofthiskindofcolumn，inwhichthreedifferentcontrolschemesareemployedInthefirstscheme，reboilratioisconstantwithvariablebottomproductcomposition；inthesecondscheme，reboilratioisvariableandtheheavykeycomponentcompositioninthebottomproductisnearlyconstant，andthethirdisanoptimaloperationwhichcouldobtainmoreprofitAmongthesethreecontrolmodes，thethirdisthemostdifficulttooperate，sincebothcontrollersforrefluxflowandreboilerheatinputareoperatedmanuallyThisworkdemonstratestheoperationofabatchstrippingcolumn，providessomepracticalguidlinesforthestartupandoperationofthecolumn，showshowthecolumncanberununderdifferentoperatingmodes，andclarifiestheeffectofsomekeycontroltuningonthecolumnperformanceHowever，thisworkisadynamicsimulationThepracticaloperationofabatchstrippingdistillationcolumnstillneedstobeinvestigatedindetailREFERENCES1Salomone，HE，Chiotti，OJ，Iribarren，OA，“Shortcutdesignprocedureforbatchdistillation”，IndEngChenRes，36(1)，13一136(1997)2Sundaram，S，Evans，LB，“Shortcutprocedureforsimulatingbatchdistillationoperations”，IndEIenRes，32(3)，511518(1993)3Yang，zhC，Yu，GC(KT)，Mo，zhM，ea，t“Studyonoptimalstrategiesandmicrocomputercontrolofbatchdistillation()Batchdistillationcolumnanditsmicrocomputercontrol”，J(ChemIndEng(China，40(3)，28一286(1989)(inChinese)4Lotter，SP，Diwekar，UM，“Shortcutmodelsandfeasibilityconsiderationforemergingbatchdistillationcolumns”，IndEngChemRes，36(4)，760767(1997)5Scrensen，E，Skogestad，S，“Comparisonofregularandinvertedbatchdistillation”，ChemEngSci，51(22)，4949一4962of1996)分批冲孔模板精馏塔的操控许松林，JoseEspinosab，HectorESalomoneb，OscarAIribarrenba中国，天津，300072，天津大学，国家精馏工程技术研究中心b阿根廷，桑塔费，康尼赛特，INGAR发展与设计学院摘要当大量的轻的成分在流量中很少和高纯度产品回收时分批冲孔模板精馏很重要，批量精馏塔的操控与镇流器的作用是相同的。然而，冲孔模板的控制系统是不同的。在这篇论文里，我们探索冲孔模板三种不同的控制方法：Hysys(HyprotechLtd1997)，最主要的不同之处是重沸器液相控制图；（a）以回流量控制;（b)以重沸器热负载控制；（c）以底部产品流量控制。在此论文里阐述分批冲孔模板精馏塔的操控最主要的特征是不同的控制流程图，分批冲孔模板控制开始时提供了准则，将要讨论一些柱面上的控制调谐参数。图1分批冲孔模板的控制流程1-塔体；2-重沸器；3-冷却机；4-整流器；LC-液面控制器；PC-压力控制器关键词分批冲孔模板控制操作1简介随着化工工厂向着大规模精细生产和专业化工产品方向发展，批量生产变得比较流行，这样简易方法对于产品需求的频繁变化起关键作用。批量精馏塔是固有简易特性的，正如一个柱可以由一个多组分供给分成许多不同的组份，这样批量精馏的用途对于一些化学，食品和药物公司的高价值的化工产品的分离和提纯变得越来越重要。传统的，最流行的批量精馏方法被称为整流柱，它有一个大的重沸器，对它所有的供给都是变化的，并且不同产品从顶部分离开。操作整流塔有三种方法：（1）回流量为恒量并且精馏组份为变量，（2）回流量为变量并且精馏的主要组份为恒量，（3）最佳回流量协调了（1）和（2）并且建立在最经济的试验。批量冲孔模板与批量整流是相反的。在它的顶端有它的储存容器并且产品从塔的底部分离出。当大量的轻的成分在流量中很少和高纯度产品回收时分批冲孔模板精馏很重要。批量精馏塔的操控与镇流器的作用是相同的。然而，冲孔模板的控制系统是不同的。在论文中，我们探索Hysys(HyprotechLtd1997)的批量冲孔模板三种不同的控制方法，图表1给出了控制图。最主要的不同之处是重沸器液相控制图；（a）以回流量控制;（b)以重沸器热负载控制；（c）以底部产品流量控制。（a）底部产品的组分（b）塔体中的温度（c）质量流量（d）顶部和底部的流量在此论文里阐述分批冲孔模板精馏塔的操控最主要的特征是不同的控制流程图，分批冲孔模板控制开始时提供了准则，将要讨论一些柱面上的控制调谐参数。2模拟实验仪器模拟实验仪器和三种控制图是相同的，脱模塔有个重沸器和2m3和5m3的冷凝器，他的直径是0.5m.供给成分是甲醇（0.05）和乙醇（0.95）（馏分）的混合物。占冷凝器容量的80%，开始时，板是干启动的，但是重沸器是由相同的混合液的液相点控制的。底部产品乙醇的规范是0.999.所有的仿真实验程序是从冲模开始直到关键的组份达到规范，然后底部产品阀开启使产品分离，当产品组份低于规范时产品阀关闭。3结果和讨论3.1通过回流量控制重沸器液面在控制图中【图表1（a）】,重沸器液相百分比是由回流量自动控制的，重沸器的热输出和底部产品的流量是手动控制的。开始时，重沸器的热输出是设定的，重沸器的液面随着轻成分的蒸发而降低，这将导致回流自动地流向重沸器。重沸器的液面控制是可逆的，所以当重沸器的液面较高时，回流量将较少。当关键组份是成分达到其规范时，底部的阀开启，一旦它低于规范，底部产品流出阀就手动关闭，这样的话，当乙醇成分达到0.999，底部产品流出阀开启，当乙醇成分低于0.999，底部产品流出阀关闭。图表3重沸器液面的波动图表2表示了此操作模式的动态过程。在重沸器液面和回流之间存在时间滞后，尤其是当阶段数目很大时。为了在整个控制中达到一个稳定的重沸器的液面。必须仔细考虑两个方面。如果回流阀过大，当液面降低时，重沸器的液面控制器将从重沸器得到比预设多的回流量。然后回流阀将会关闭。这使重沸器液面频繁波动。图表3展现出了一种情况，在这种情况底部关键成分的组成是不稳定的，另一方面是重沸器的液相参数应该合理选择尽当底部控制器的比例试用时。控制器的比例增益Kp应该在4.0和8.0之间。如果Kp值太小，就很难使重沸器液面控制达到稳定。图表4展示了重沸器液相百分比与相同的重沸器的Kp值之间的关系。从图表4中，很明显的看出如果Kp值低于4.0时重沸器的液相百分比将低于预设值的50%。如果Kp值在4.0和8.0之间，重沸器的液面会处在预设值的附近。图表4Kp值对重沸器液面的影响3.2通过重沸器的热输出控制重沸器的液面在控制图中【图表1（b）】中，重沸器的液面是由重沸器的负载自动控制的，回流和底部产品的流出是手动控制的。开始时，回流阀须有一个特定值。重沸器的液面增加将导致对重沸器的热输入。重沸器的液面控制器的功能是直接的，这意味着重沸器液面越高，重沸器的热输入越多。当关键组份是成分达到其规范时，底部的产品流出阀手动关闭。当关键组份是成分降至0.999时，底部产品流出阀和回流阀也手动关闭。图表5表示了此操作模式的动态过程。很明显的看出煮沸的大量流量和冷凝器的液面以及重沸器都回流至控制初期。这是由于重沸器的动态响应度的热输入对控制器的