示例手册（可打印）

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9

CHEMCAD5™

Version5.0

BookofExamples

Part1:Steady-StateSimulation

Release012401

©August1999

TableofContents

TOC\t"Topictitle;1"

AtmosphericDistillationofCrudeOil(ATMOS)

5

BlendingofCrudeOil(BLENDING)

7

Cat-CrackerGasSeparation(CRACKSEP)

8

De-IsobutanizerSample(DEBUT)

9

HydrotreaterUnitSimulation(hTREAT)

10

TEGGasDehydration–Regeneration(TEGDEHY)

11

Propane-PropyleneSplitter(PROPSPLT)

13

SourWaterStripper(SOUR)

15

VacuumTowerwithTBPAssay(VACUUM)

17

MEKProcess.Dehydrogenationofsec-Butanol(MEK_15K)

19

MTBEProcesswithH2SO4Catalyst(MTBEACID)

21

ThePhthalicAnhydrideProcess(PA)

23

EthylAcetatebyReactiveDistillation(ESTER)

25

AmmoniaSyngasPlant(SYNGAS)

27

WetDesulfurizationofFlueGas(WET-SOx)

28

CO2RemovalbytheBenfieldProcess(BENFIELD)

29

SelectiveH2SRemovalwithMDEA(MDEA)

30

GasTurbineSimulation(GASTRBIN)

31

PowerPlantSteamBalance(POWER)

32

DetailedModelofanIndustrialPowerPlant(POWERBLOCKSIMULATION)

34

BatchDistillationofEssentialOils(CITRON)

35

Whoshouldreadthis?

ThisbookletpresentstheapplicationsofCHEMCAD5ProcessSimulationSoftwareinvariousprocessindustryareasasvariedasoilrefiningandcosmeticsmanufacture.TheexceptionaleaseofuseofthisprogramhaswonCHEMCADextensiveworldwideacceptance,fromengineeringcompaniestoprocessplantstouniversities.

ThebookispresentationmaterialforcompanieswhoconsiderlicensingCHEMCAD5.ItcanalsobeusedbyCHEMCADusersasareferencetoseveraloftheexamplejobsinstalledwithCHEMCAD

Anotheravailablepublication,TheCHEMCAD5TrainingBook,isintendedforexistingCHEMCADusers,orforpersonswhoaretestingtheusefulnessoftheprogramfortheirapplications.TheCHEMCADTrainingBookconsistsoffilescontainingexampleprojects,andthebookitselfincludesextendednotes,whichprovidepracticalsolutionstopracticalproblemsoftenmetbynovices.

AllpicturesincludedinthisbookwerecreatedwithCHEMCAD5.

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10

Databoxesandgraphicscanbeplaceddirectlyontheflowsheet,formingtheMainProcessFlowDiagram(PFD).Alternateprocessflowdiagramscanbealsocreatedandedited.

AtmosphericDistillationofCrudeOil

DESCRIPTION:

Crudeoilisheatedinprocessfurnaceto400F.Thecrudethenenterstower1nearthebottomstage.Thetowerisequippedwith12stages,acondenser,onesidestripperfornaphtha,onesideheatexchanger,andonepumparound.Thebottomsofthetowerareheatedto600Finthesecondfurnace,andsenttotower2.Tower2isequippedwith15stages,acondenser,twosidestrippers(forkeroseneanddieseloil),onesideheatexchanger,andonepumparound.

Thebottomsofbothtowersaswellasallstrippersarefedwithlivesteam.

ThisexampleshowsusageoftheTowerPlusdistillationmodelandamethodtoperformcrudeoilcharacterization.

BlendingofCrudeOil

DESCRIPTION:

CHEMCAD5hastheabilitytogeneratecrudeoilpseudo-componentsaccordingtouserprovideddistillationcurves.CHEMCAD5supportsthefollowingblendingoptions:

The"Blend"optioncangeneratepseudo-componentsbyaveragingdistillationcurvesofallstreamsundercharacterization.

The"NoBlend"optionallowscharacterizingcrudeoilstreamsindividually,sopseudo-componentsgeneratedfromdifferentstreamscanbedistinguishedintheproductstreams.Thismakesevaluationofdistributionofvariouscrudeoilsintheflowsheeteasy.

CHEMCAD5doesallreportingtouser-selectededitorsorwordprocessorssuchasMicrosoftWord,Wordpad,ornotepad;graphicscanbecopieddirectlytotheWindowsClipboard.DatapointsforplotscanbeexportedtoeitherMicrosoftExcelordelimitedtextforotherspreadsheets.Thisallowsyoutofreelycomposeyourreportsusingyourpreferredofficesoftware.

CHEMCAD5.00Page1

StreamNo.3

TBPat1atm

LiqVol%

0-18.4

575.1

10110.2

20188.6

30272.6

40338.8

50390.1

60435.0

70480.0

80528.7

90576.6

95626.9

100711.5

Cat-CrackerGasSeparation

DESCRIPTION:

Thisisasimulationofanexistingprocess.Crackergas(stream1)isbeingmixedwithrecycledgasstream(stream10),flashed(Unit1),compressed(Unit4)to12kG/cm2G,cooledbyaircoolerandanaftercooler(Units5and6),thenflashedagain(Unit7).Netgasandliquidfromthecompressionstagearefedtoacollector(Unit12),whichisacentralpointoftheoperationfromthebalancepoint.Off-gas(stream25)ofthiscollectorissenttotheabsorber(Unit15),whichisalsofedwithbothstabilized(lean)andunstabilizednaphtha.Thetopproductoftheabsorberishydrogen-enrichedgas.

ThebottomsfromUnit15aretransferredtothecentralcollector(Unit12).Theliquidproductofthecollectorgoestothereboiledstripper(desorber),wherethebottomsleavesystemasrichnaphtha(stream21),whilethetopproductreturnstothecollector.

ThisflowsheetillustratesCHEMCAD'susefulnessinmodelingmulti-recycledprocesses,applicationsoftheTowermodelforabsorption,anddesorption,andusageofspecial(built-in)thermodynamiccoefficientsforethane/ethyleneandpropane/propylenesystems.

De-IsobutanizerSample

DESCRIPTION:

Thisexampledemonstrateshowtomakethepreliminarydesignofani-butane/n-butanesplitter.

Giventhefeed'scomposition,flowrateandthermalstate,andassumingpressuredrops,a50theoreticalstagetowerequippedwithacondenserandareboilerwasdesigned.Specifiedwerea99%recoveriesofn-butaneandi-butanetodistillateandbottoms,respectively.Afterseveraltrials,anoptimumfeedstagelocationwasfound.TheSizing>Traysoptioncandotraysizing,calculatepressuredropsacrosstrays,andestimatestageefficienciesbyO'ConnellandChucorrelations.Sizing>Packingoptioncancalculatepressuredropthroughapackedcolumn,includingamodernandaccuratecorrelationofMackowiak.

TheCC-THERMmodulecandoarigorousdesignofthecondenserandthereboiler,includingpressuredrops.TheTowermodelcanbeupdatedwiththesedataandrerun,resultinginarigorousdesign.

HydrotreaterUnitSimulation

DESCRIPTION:

Theexampleshowshowtomodelrefiningtechnologiesofundefinedchemistry.TheprocessistoremovesulfurandnitrogenimpuritiesfromC6+petrocutbyhydrogenation.

Thefeedstock(stream1)ispumpedfromtankageandmixedwithrecyclehydrogengas.ThenitispreheatedwithhotreactorproductgasintheCFEXheatexchanger.Thereactorfeedisthenheatedneartothereactiontemperatureinaprocessfurnace,andintroducedtotheadiabatichydrogenationreactor.

Inthereactor,sulfurandnitrogenimpuritiesareconvertedintohydrogensulfideandammoniarespectively,andalkeneboundsarebeingsaturated.TheheatofhotreactiongasesisrecoveredintheCFEXexchanger.

HeatisfurtherrecoveredintheH2EXheatexchanger,wheretherecycledhydrogenispreheated.Thecooledmixtureissenttoadrumseparator,wheregasesareflashedofffromtheheavyliquidproduct.Thegasesarewashedwithprocesswater,cooled,andsenttoaflashdrum,wherelighthydrocarbonproductandwastewaterareseparatedfromtherecyclegas.TherecyclegasispurgedtoremoveexcessH2SandNH3producedintheprocess,thegasisre-compressedandmixedwithfreshH2make-upstream,andtherecyclereturnstotheprocess.

TEGGasDehydration–Regeneration

DESCRIPTION:

Currently,CHEMCADincludes34thermodynamicmethodstodeterminephaseequilibria,aswellaselectrolytepackageandsolidsasbuilt-infeatures.K-Valuemethodsvaryfromveryuniversaltospecializedones.Processnaturalgasdehydrationwithtriethylglycol(TEG)hasitsownK-ValuemethodinCHEMCAD5.

Theflowsheetdescribesatypicaldehydrationunit.Gasenterstheunitat85degF,saturatedwithwater.Itisdriedinthedehydratorcolumnat500psiabycontactwithleanTEG.TherichTEGisthenflashed,heatedandregeneratedwithacombinationofindirectheatandaslipstreamofthedriedgas.Theregenerationcolumnhasareboiler,condenserandpackedsectionbelowthereboiler.Withthisflowsheet,thewaterremovalfromaprocessornaturalgasstreamasafunctionofoperatingvariablesiscalculated.TheusermaydefinecirculatingTEGflow,columnpressures,flashpressure,strippinggasflowandheatexchangerperformance.

Propane-PropyleneSplitter

DESCRIPTION:

Propaneandpropyleneareverydifficulttoseparateonefromanother,astheyareclose-boilingcomponents.Nonetheless,distillationatelevatedpressureisacommontechnology,providedsufficientnumberoftraysexistsinthedistillationcolumn.

Calculationsofa148actual-traytowerarepresentedinthisexample.TheSCDSdistillationmodelwasusedtoaccommodatebignumberoftrays,andtoaccountforactualtrays.

Propane/propyleneandethane/ethylenevapor-liquidequilibriaareaffectedbyinteractionsbetweenthecomponents.SpecialBinaryInteractionParametersforthePeng-RobinsonEquation-Of-Statewereusedtoreflectthesenon-idealities.

SourWaterStripper

DESCRIPTION:

Inthisexample,theTowerPlus(TPLS)modelhasbeenusedtosimulatestrippingwastewaterfromHydrogenSulfideandAmmoniadowntothelevelof5ppm.ThisisanotherapplicationoftheTPLSmodel,whichisnormallyusedtosimulateatmosphericandvacuumdistillationofcrudeoil.

Thetowerisequippedwithareboiler,andapumparoundisusedtogenerateinternalreflux.

Aspecialthermodynamicmodel,SOUR,hasbeenusedtocalculateequilibriainthesystem.

ThepicturebelowistheProcessFlowDiagramincludingaStreamDataboxes.CHEMCAD5allowstoplaceStreamandEquipmentDataboxesonaPFD,andyouarefreetoselectpropertiesandtheunitsofmeasurethatwouldappearthere.

VacuumTowerwithTBPAssay

DESCRIPTION:

Atmosphericresidueisdistilledundervacuumintofueloil,twogradesofvacuumgasoil,andvacuumresidue.Thepreheatedfeedstreamentersthebottompartofthetower,whichisadditionallyheated.Twopumparoundsprovideinternalreflux.

TheprocesshasbeenmodeledwithaTowerPlus(TPLS)distillationmodule.

TheexampleshowshowflexibleastospecificationstheTPLSmoduleis.(Forinstance,youmayreplaceacondenserwithapumparound,orthereboilerwithsideheatexchanger,ifyouneedit.)ItalsodemonstratescharacterizationoftheoilfeedbyTBPassay.(ThefigurebelowshowsfeedandproductcharacterizationcurvesafterautomaticTBP-D1160inter-conversion).A

thermodynamicK-Valuemodelmostsuitableforvacuumdistillationofheavymaterialwasselected.

MEKProcess.Dehydrogenationofsec-Butanol

DESCRIPTION:

Theflowsheetshowsatechnologytomake15,000MTPYofmethylethylketone(MEK)bysec-butanol(SBA)dehydrogenation.Itisadesignstudy.

FreshSBAispumpedontothetopofascrubber(1),whereresidualMEKisremovedfromabyproducthydrogenstream.ThenSBAisvaporizedandsuperheatedbeforeitentersthereactorsystem(6),wheresec-butanolisdehydrogenatedinavaporphasereactionoverasolidcatalyst:

CH3-CHOH-C2H5-->CH3-CO-C2H5+H2

Thereactionishighlyendothermicanditistypicallycarriedoutinseveralreactorsconnectedinparallelorinseries.

Accordingtoliterature(Kirk-Othmer),conversionof90%canbeachievedfairlyeasily.

Thereactoreffluentiscondensed,andhydrogenisflashedoff.CrudeMEKentersthedistillationcolumn(7),whereMEK-H2Oazeotropegoestothetop.Theproductisdehydratedonarocksaltbed,andtheMEK-richphaseiscondensedandrecycledtotheazeocolumn.DriedmixtureofunconvertedSBAandMEKisthendistilledinto99.5wt.%MEKproductandSBA,thelatterbeingrecycledtotheprocessfeedstream.

ExampleintheTrainingBookexplainshandlingmultiplerecycles,areactormodel,non-idealVLequilibria,controllers,andmodelingspecialoperations,likerocksaltbedunit.

MTBEProcesswithH2SO4Catalyst

DESCRIPTION:

MTBEismadecommerciallybycatalyticreactionbetweenmethanolandi-butylene.Awidelyusedcatalystisanacidicionexchangeresin.Thisflowsheetshowsthealternateroute,wheresulfuricacidisusedascatalyst.Theflowsheetwasmadeaccordingtopublisheddata.(Al-Jarallah,A.M.,andLee,A.K.K.,"EconomicsofnewMTBEdesign",HydrocarbonProcessingJuly1988.)

Theprocessistomakeapproximately100,000metrictonsperyearoftheMTBEproduct.

AmixtureoffreshandrecycledmethanolismixedwithaC4streamandamixtureoffreshandrecycledsulfuricacid,andreactedatelevatedtemperatureandpressureintwosetsofmultistage,intercooledreactorsinliquidphase.MostofH2SO4isthenseparatedinthesettlerandrecycledtoreaction.Sourorganicphaseisthenneutralizedwithalkaliandwashedwithwater.Methanolisrecoveredfromtheaqueousphasebystrippingwithlivesteamandrecycledtotheprocess.ThewashwaterrecycleispurgedtoavoidNa2SO4build-up.WashedorganicphaseisdistilledtoseparatetheMTBEproductfromspentbutanes.

TheTrainingBookexplaintheimportanceofConvergenceParametersinconvergingbig,multi-recycledflowsheets.CalculationsofWAREnvironmentalReporthavebeendemonstrated.Thisfeatureallowstheusertoassesstheenvironmentalimpactofwastestreams.

ThePhthalicAnhydrideProcess

DESCRIPTION:

OneoftheroutestomakePhthalicAnhydride(PA)istooxygenateo-Xylenewithairinacatalyticprocess.

Extensivelaboratory/computationalworkhasbeencarriedouttodevelopactualkineticmodelforthereactor.ThenthedatawereinputtoCHEMCAD'sKineticReactormodelastheExtendedKineticEquation.Heattransferwasalsoincludedintothemodel.

Aswewerenotpermittedbythetechnologyownertopublishdata,theTrainingBookexampleinvolvessimplermodelforasimilarprocess.

Reactiveabsorptionhasbeenemployedtomodelascrubberconvertinganhydridesintorespectivecarboxylicacids.

EthylAcetatebyReactiveDistillation

DESCRIPTION:

Forreversiblereactions,theequilibriumstatecanbeshiftedindesireddirectionby,i.a.,addingoneofreactantsinexcessorremovingproductsfromthereactionmass.Thisprincipleisthebackgroundofreactivedistillationtechnique.Productsareseparatedandremovedfromthedistillationcolumnduetodifferenceintheirrelativevolatilities,andduetocounter-currentreactants'flow,reactantsareinexcesstoeachotheratseveralcolumnstages.

ThisexampleshowshoweasilyCHEMCAD5cancopewithreactivedistillationandextremelynon-idealsystems.Notonlyisareversiblereactionthere;AceticAcid,Ethanol,Water,andEthylAcetateformathermodynamicallycomplexsystemwithtwo-liquidphasesandvaporphaseassociation.Forachemicalengineer,though,theonlytaskistocorrectlyselectthermodynamicmodels,enterreaction(s)equilibriumorkineticcoefficients,andspecifythecolumnashewoulddowithmore'typical'distillation;CHEMCAD5willdotherest.

AmmoniaSyngasPlant

DESCRIPTION:

Reallifetechnologytomake3:1H2/N2syngashasbeenshown.Itinvolvesprocessessuchasmethaneconversionwithsteamandair,COtoCO2conversion(theShiftreaction),andthemethanationreaction.Theflowsheetincludesmultiplerecycleloops.

CHEMCAD5'sEquilibriumReactorandGibbsReactormodelsareperfectlyfittorigorouslycalculatereactionsinvolvedinsyngasmanufacture.TheEquilibriumReactorhasequilibriumconstantsformethanation/shiftreactionbuilt-in,soitdoesnotrequireanyinterventionfromtheuser.

CHEMCAD5isveryusefulineverydayplantoperation.Oncetheplanthasbeenmodeledwithaflowsheet(evenasimplifiedone),itisveryeasytofindouttheprocessbottlenecks,unitswithexcessiveutilityconsumption,etc.Veryoften,itisenoughtochangesomeprocessparameterstosavesubstantialmoneyandtomakebetterproductwithexistingequipment.Sometimesasmallrevampwouldbeadequate.Whenthestoryistheheatexchanger,theadditionalmoduleCC-THERMcanhelptorateexistingexchanger,makemodificationsintheheatexchanger,ordesignanewone.IthasbeenproventhatthesavingsachievedwithCHEMCADandCC-THERMcanexceedmanytimestheinitiallicensecost.

WetDesulfurizationofFlueGas

DESCRIPTION:

Oneofmethodstocleanupfluegasisthewetprocess.Aqueouslimesuspensionisintroducedontothetopofaspraytower,andfluegascounter-currentlycontactsliquiddroplets.Sulfurdioxideisconvertedintosulfites,andCO2isreleased.

JobName:wet-sox

StreamNo.1234

StreamNameLime+H2OFluegasCleanGasSulfite

TempC20.0000*40.0000*15.265415.1076

Presbar1.1000*1.1000*1.00001.0000

EnthMJ/hr-8.5824E+005-1.5906E+006-1.9039E+006-5.4498E+005

Vapormolefraction0.000001.00001.00000.00000

Phvalue10.14980.00000.00006.2584

Ionicstrengthmolal0.00060.00000.00003.2546

Totalkmol/hr2828.008561882.047862976.84971755.4089

Totalkg/hr55296.23031800000.01391819076.181236219.9106

TotalstdLm3/h50.94652221.74232241.595831.2470

TotalstdVm3/h63385.981387002.411411540.8939345.12

Flowratesinkmol/hr

SulfurDioxide0.000028.09650.00050.0000

CarbonDioxide0.00004089.97954114.89030.0824

CalciumCarbonate52.99160.00000.000027.6882

Water2774.99480.00001098.00721673.8902

Nitrogen0.000057764.000057764.00000.0214

H+0.00000.00000.00000.0000

OH-0.00510.00000.00000.0000

CO3--0.00330.00000.00000.0008

HCO3-0.00510.00000.00000.3176

HSO3-0.00000.00000.00005.8884

SO3--0.00000.00000.000022.2080

Ca++0.00840.00000.000025.3118

EnhancedelectrolytepackagebeinganintegralportionofCHEMCAD5makesthissortofcalculationsfeasible.TheuniqueTrueSpeciesApproachtreatselectrolytespeciesastheywereregularcomponents,sothecalculationresultsreflecttruedistributionofmaterialintomoleculesandions.TheElectrolyteExperttoolhelpssettinguptheelectrolytesystemveryeffectively;thisactionisalmosttransparenttotheuser.

CO2RemovalbytheBenfieldProcess

DESCRIPTION:

WhatyoucanseeinthepictureaboveisthesimulationofanexistingplanttoremoveCO2fromaprocessstreambyabsorption/regenerationwithahotpotassiumcarbonatesolution.CO2isabsorbedbychemicalreaction,anditisthetypeofcalculationsCHEMCAD5ElectrolytePackagehasbeenmadefor.

ThissortofsimulationrequiresapplyingtheTrueSpeciesApproach,whereregularcomponentsandelectrolytespeciesaretreatedequally.

CHEMCAD5hasadatabaseofionicreactionsbuilt-in.Manyindustriallyimportantsystemshavebeencovered.Incasesomereactiondataaremissing,CHEMCAD5wouldtrytocalculateequilibriumcoefficients.ElectrolyteRegressionfacilityisalsoavailable.

SelectiveH2SRemovalwithMDEA

DESCRIPTION:

ThisexampleisaselectiveH2Sremovalbyusing50weight%MDEAina10trayabsorber.

ThisproblemwascalculatedbytheApparentComponentelectrolytemethod,where'visible'componentsareseparatedfromtheionicspecies.

TheconstantsfortheMDEAprocesshavebeentakenfromtheCHEMCAD'sionicreactionlibrary.

CHEMCAD5includesenhancedSCDSdistillation/absorptionmodel.Itallowsspecifyingstageefficienciesforindividualcolumntrays,aswellasstageefficienciesforindividualcomponents.Inthisexample,theCO2absorptioniscontrolledbymasstransfer,soindividualstageefficienciesforcarbondioxidehavebeenapplied.

Ref:Jou,F.Y.F.D.OttoandA.E.Mather,"SolubilityofMixturesofH2SandCO2inaMethyldiethanolamineSolution".Paper#140bAIChEAnnualMeeting,MiamiBeach,FL(Nov2-7,1986)

GasTurbineSimulation

DESCRIPTION:

Atypicalgasturbineconsistsofanaxialcompressor,fuelcombustionchamberandanexpanderwhichdrivesthecompressorandanyexternalloadorloads.Formodelingpurposesonly,theworktodrivethecompressorandexternalloadsareconsideredseparately.Thedesignorratingofaturbinesystemdependsonhowthecontrolsareconfigured.CHEMCAD5candefinethetheoreticalworkrequirementsandfuelforadefinedloadorframesize.

Thisexampledefinestheairandfuelrequirementsforaturbine,whichdrivesanelectricalgeneratorundercombustionconditions,asdefinedbyexcessairrequirement.

Theflowsheetisacloserepresentationofa