清华大学《化工系统工程基础》column start-u

AspenPlusTraining

ColumnStart-up清华大学邱彤AspenPlusDynamicsHelp–ColumnStart-up2023/4/202.ColumnStart-up2023/4/203ComponentCCl4inCTC>=99%(Mass)T：20℃P：6barFlow:10000kg/hrComponent(Mass-Frac)CCl4:

0.4CHCl3:0.54CH2Cl2:0.06N2:0

Calculationtype:EquilibriumNstage:20Condenser:Partial-Vapor-LiquidT:80.3Distillaterate:6164kg/hrRefluxratio:5(Mass)Feedstage:10(on-stage)Pressure:Stage1:2barStage2:2.02barPdrop:0.235barInitialvalueThestart-upofadistillationcolumnthatseparatesamixtureofCH2CL2,CHCL3andCCL4.FEEDCOL1DesignSpec:Out_P:VVENT:1.01VTOP:1.01VCTC:1.01VFEED:2.12444Basemethod:NRTL.Overview2023/4/204Thissimulationisofthestart-upofadistillationcolumnthatseparatesamixtureofCH2Cl2,CHCl3andCCl4.Thedynamicsimulationisapressuredrivensimulation,sotheAspenPlusmodelincludesvalvesonthefeedandproductlines.InAspenPlusDynamics,thecolumnisstartedupfromacold,emptyinitialcondition.Thepre-built"Empty"scriptisusedinAspenPlusDynamicstoresetthecolumntobeemptyandfullofNitrogenat20Cand1.01bar.Tousethisscript,NitrogenmustbeincludedinthecomponentlistintheAspenPlusmodel.Duringstart-uptheinertgashastobeventedfromthecolumnandsobothvaporandliquidtopproductstreamsmustbepresent.Therefore,intheAspenPlusmodel,bothliquidandvaportopproductshavebeenconnectedandaCondensertemperaturespecificationisusedwhichgivesasmallvaporproductflow..GotoAspenPlusDynamicsmodel2023/4/205BeforeenteringanydynamicdatainAspenPlus,youwouldusuallyrunasteady-statesimulationtoensureitcompletesnormally.Beforeyoucanenterdynamicdata,youhavetoclicktheDynamicbuttonontheDynamictoolbar.Thisenablesyoutoaccessthedynamicinputdatasheetsforeachblock.TheRadFracblock(COL1)containsformsthatrequiredynamicdata,sothestatusindicatoronthestatusbarchangestoRequiredInputIncomplete.Condenser:LMTDReboiler:Constanttemperature—140℃RefluxDrum:VerticalEllipticalLength:2mDiameter:1mSump:EllipticalLength:2mDiameter:1.5mHydraulics:Simpletraystage1:2Stage2:19Diameter:1.5mCOL1TheSimpleTrayoptionhasbeenusedintheHydraulicstaboftheColumnDynamicfolder.TheRigorousoptionisnotsuitableforsimulatingthezeroflowratesduringstartup.ExportDynamics(PressureDriven).AspenPlusDynamics2023/4/206.Initialization-Reconfigure2023/4/2071.SwitchtheoutputconnectionofthePressureControllerCOL1_CondPCfromtheVentValvetotheCondenserMediumflowrateasfollows:ClickthecontrolsignalbetweenCOL1_CondPCandvalveVVENT.Right-click.SelectReconnectDestination.ReconnectittotheinputconnectionatthetopoftheCondenser.Selectthefirstvariableinthelist,Mediumflowrate.ClickOK..2023/4/2082.ReconfigurethePressureControllerasfollows:Double-clickonittodisplaytheFacePlate.ClickontheyellowConfigurebutton.ClickontheInitializeValuesbutton.SettheGainto10.ControlleractionisDirect.SwitchtotheRangestab.SettheRangeminimumfortheOutputto1000kg/hr.ClosetheConfigureformandFaceplate..Initialization-addFC2023/4/2093.Addaflowcontrolleronthecolumnfeedasfollows:DragaPIDIncrmodelontotheflowsheet.Right-clickthecontrollertorenameittoFC.DragaControlSignalstreamontotheflowsheet.ProcessVariable:ConnecttheControlSignalstreamtotheoutputarrowontheFEEDstreamlabel.ScrolldowntoselecttheTotalmassflowvariable.ClickOK.ConnecttheotherendofthecontrolsignaltotheinputofFC.SelecttheProcessvariableinput.ControllerOutput:RepeatthisprocesstoconnecttheControlleroutputfromcontrollerFCtothevalveVFEED.Configure:ClicktheInitializeValuesbuttonandthenchangethecontrolleractiontoReverse,thatis,ifthefeedflowistoohighthecontrollershoulddecreasethevalveposition.Changetheintegraltimeto0.5minutes..Initialization-addTC2023/4/20104.AddaTCasfollows:DragaPIDIncrmodelontotheflowsheet.Right-clickthefiletorenameittoTC.ProcessVariable:Theprocessvariableisthetemperatureofstage16inthecolumnControllerOutput:TheoutputistheReboilerheatingmediumtemperature.Configure:ChangetheactiontoReverse.SetthePVrangeto80-125andtheOPrangeto20-260..Initialization-Empty2023/4/2011Closethevalve,VVENT,inthecolumnventstreamasfollows:SelectthevalveVVENT.Right-click>Forms>Manipulatetodisplaythevalveposition.Changethepercentageopentozero.Runthe"Empty"scriptandresetthecolumntobefullofNitrogenasfollows:SelecttheColumnblock.Right-click>Scripts>Empty.WaitfortheScripttofinishrunning.ClickOK..Initialization2023/4/2012OpentheFacePlatesforalltheControllers.ClicktheHandicontoswitchalltheFacePlatestoManualMode.IntheFacePlates:Settheoutput(OP)oftheflowcontroller,FC,tozero.Settheoutputofthetemperaturecontroller,TC,to20C.Settheoutputofthepressurecontroller,COL1_CondPC,to1000kg/h.ChangetheAspenPlusDynamicsrunmodefromDynamictoInitializationasfollows:ClickRun.ClicktheTakeSnapshoticon.SavethesnapshotasColstart..CreatetheTaskColstarup2023/4/2013CreatetheTasktostartupthecolumn.GototheFlowsheetsectionoftheSimulationExplorer.Double-clicktheAddTaskicon.Namethetaskcolstartup.Deletethedefaultsettingsofthistask.Right-click>InsertFile>browsetofindthecolumnstartup_task.txtfileincludedwiththisexample.Analyzethetasktounderstandwhatitwilldo.Right-click>Compile,orpressF8,tocompilethetask.Closethetexteditorwindow..Task2023/4/2014TaskcolstartupRunsat0//Ensurethatcontrollersareinmanual//Addsomefeedtothecolumn//Waitforthesumpleveltoreach2mandthenturnoffthecolumnfeed//Putthepressurecontrollerintoauto&changesetpointto2bar//Openthecolumnventvalvetopurgethenitrogen//Increasereboilersteamtemperaturegradually//Startthecolumnreflux//Continueincreasingsteamtemperature//CloseventvalvewhenN2ispurged//Puttherefluxdrumlevelcontrolintoauto&changesetpointto2//Addsomemorefeeduntilthesumplevelreaches2m//Increasereboilersteamtempto135//Waituntilthelevelintherefluxdrumrisesto0.5then...//...putthesumplevelcontrollertoautomatic//andincreasetherefluxratetothefinalvalue//startthecolumnfeed-putthefeedvalveto50%open//Rampupthesteamtemperatureto140//Waituntilstage16temperaturereaches101.5andputthetemperaturecontrollertoAutomode//Changetherefluxlevel&sumplevelsetpointstothefinalvalue//Waitfor1morehourandpausethesimulation.2023/4/2015TaskcolstartupRunsat0………………//Putthepressurecontrollerintoauto&changesetpointto2barBlocks("COL1_CondPC").Automan:0;Blocks("COL1_CondPC").SP:2;//OpenthecolumventvalvetopurgethenitrogenBlocks("VVENT").pos:100;//IncreasereboilersteamtemperaturegraduallyBlocks("TC").OPMan:60;Wait0.1;Blocks("TC").OPMan:80;Wait0.1;Blocks("TC").OPMan:100;Wait0.1;//StartthecolumnrefluxBlocks("COL1").Reflux.FmR:30000;Wait0.05;//ContinueincreasingsteamtemperatureBlocks("TC").OPMan:120;//CloseventvalvewhenN2ispurgedBlocks("VVENT").pos:0;………….Colstarup2023/4/2016Double-clickthecolstartuptaskintheSimulationExplorertoactivateit(otherwiseitwillnotbeused).Considermakingsomeplotsshowingsomeofthekeyvariables,suchas:ReboilerDutyQRebReboilerHeatingMediumTemperatureTmedRebMassRefluxRa