CrudeTowerSimulation–AspenPlusv8.6
StepstosetupasimulationinAspenPlusv8.6tomodelacrudetowersystemconsistingof:
 CrudeOilPreheatTrain
 AtmosphericCrudeTower
 VacuumCrudeTower
 DebutanizertostabilizetheoverheadnaphthastreamfromtheAtmosphericCrude
Tower
ThefeedstocktothecrudesystemwillbeanequalmixofLight,Medium,&HeavyCrude
oils.
WhenthesimulationissetuptheoverallPFDshouldlooklikethefollowingfigure.
Createnewsimulationfile
StarttheprogramfromStart,AllPrograms,AspenTech,ProcessModelingV8.6,AspenPlus,
AspenPlusV8.6.Whentheprogramopenschoosethenewbutton.thereareseveral
templatesthatcanbechosen.SelecttheRefineryoptionintheleft‐handcolumn&chosethe
PetroleumwithEnglishUnitstemplate.PressCreate.
Rev0.0
‐1‐
November9,2014
Saveasyougo
Oneofthethingsyou’llwanttodoistosaveyourfilesasyougo.Thefirsttimeyougoto
theSaveAsoptionyou’llhaveseveralformatsfromwhichtochoose.Thereareadvantages
tosaveastheAspenPlusBackup(BKP)format–thefilestendtobesmaller&lesslikelyto
becomecorrupted.
Rev0.0
‐2‐
November9,2014
DefinetheComponents&thePropertyModels
Specifycomponents,fluidpropertypackages,&crudeoilassays
Thefirststepistoaddasetofpurechemicalspeciestorepresentthelightcomponentsof
thecrudeoils.TheComponent‐Specificationsformshouldbethedefault.(Ifnot,pressthe
SpecificationsitemunderComponentsintheleft‐handcolumn.)Wwillwanttoaddthe
followingpurecomponents:water,methane,ethane,propane,i‐butane,n‐butane,i‐
pentane,&n‐pentane.OneofthedirectwaystodothisistopressFind&usethesearch
formtofindthedesiredcomponents.ThefollowingformshowsasearchforH2O;key
phrasescanbeusedtowiththeEqualsorContainsoptionstofindallcomponents.Foreach
succeedingcompoundyouwillbeaskedtoreplaceoneofthecompoundsoraddtothelist;
chooseaddtothelist.
Rev0.0
‐3‐
November9,2014
Rev0.0
‐4‐
November9,2014
AspenPluswillretrieveinformationabouteachcomponent&alsocreateaComponentID
forthissimulation.YouarefreetochangetheseIDstomatchyourpersonaldesires.For
example,youchangetheIDforMETHA‐01toC1bydoublingclickingonthattextitem;after
changingthetextvalue&pressingenterAspenPluswillverifythatyouwanttoRenamethe
component&notchangeittosomethingelse.Thiscanbedoneforallofthecomponentsto
create(IMHO)morereasonableIDs.
Rev0.0
‐5‐
November9,2014
AspenPluscanguideyouthroughtheprocessofdefiningyoursimulation.Thisisdoneby
pressingtheNextbutton( ,eitherintheribbonorinthequickaccessbar).Doingthis
showsthatthenextstepistopickafluidpropertypackageontheMethods–Specifications
form.FromtheBaseMethodpull‐downlistchoosePENG‐ROB.
Rev0.0
‐6‐
November9,2014
Clickthe button.ThenextformallowsustomodifyvaluesforthePeng‐Robinsonbinary
interactioncoefficients.Wewillnotchangeanyofthemfromthedefaults.
Wenowwanttoaddassaydataforthethreecrudeoils:LightCrude,MediumCrude,&
HeavyCrude.ThedatatobeaddedisshowninthefollowingTables1to3.
Clickthe button.But,sincewewanttoaddcrudeassaydata&thisisnotanoptionon
thisform.PressCancel.
Rev0.0
‐7‐
November9,2014
Table1.AssayDataforLightCrude
Light Crude IBP EP Whole Crude 31 160 160 236 236 347 347 446 446 545 545 649 649 758 758 876 876 1015 1015 1205 1205 1350 1350 FBP Cumulative Yield [wt%] @ IBP @ Mid 0 2.5
5 7.5
10 15
20 25
30 35
40 45
50 55
60 65
70 75
80 85
90 92.5
95 97.5
Density lb/ft3 53.27
42.75
45.40
48.33
50.46
52.38
54.18
56.04
57.92
60.05
62.84
64.92
70.64
API Gravity 34.17
74.91
62.90
51.09
43.38
36.97
31.37
25.96
20.86
15.45
8.94
4.44
‐6.57
Sulfur wt% 1.77
0.019
0.031
0.060
0.379
1.064
1.698
2.159
2.554
3.041
3.838
4.503
6.382
Light Ends Analysis [wt%] Ethane 0.000 Propane 0.146 i‐Butane 0.127 n‐Butane 0.702 i‐Pentane 0.654 n‐Pentane 1.297 Table2.AssayDataforMediumCrude
Medium Crude IBP EP Whole Crude 88 180 180 267 267 395 395 504 504 611 611 721 721 840 840 974 974 1131 1131 1328 1328 1461 1461 FBP Cumulative Yield [wt%] @ IBP @ Mid 0 2.5
5 7.5
10 15
20 25
30 35
40 45
50 55
60 65
70 75
80 85
90 92.5
95 97.5
Density lb/ft3 55.00
43.47
47.14
49.42
51.83
54.08
55.90
57.73
59.77
62.30
65.74
68.08
73.28
API Gravity 28.97
71.51
55.69
47.08
38.78
31.67
26.36
21.36
16.15
10.15
2.74
‐1.87
‐11.08
Sulfur wt% 2.83
0.022
0.062
0.297
1.010
2.084
2.777
3.284
3.857
4.706
5.967
6.865
8.859
Light Ends Analysis [wt%] Ethane 0.000 Propane 0.030 i‐Butane 0.089 n‐Butane 0.216 i‐Pentane 0.403 n‐Pentane 0.876 Rev0.0
‐8‐
November9,2014
Table3.AssayDataforHeavyCrude
Heavy Crude IBP EP Whole Crude 26.8 153.6 153.6 255.1 255.1 400.5 400.5 523.4 523.4 645 645 769.6 769.6 901.9 901.9 1043.8 1043.8 1198.1 1198.1 1380.5 1380.5 1499.7 1499.7 FBP Cumulative Yield [wt%] @ IBP @ Mid 0 2.5 5 7.5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 92.5 95 97.5 Density lb/ft3 55.20
42.92
45.75
49.44
52.23
54.49
56.62
58.77
61.09
63.61
66.63
68.71
73.10
API Gravity 28.36
74.11
61.40
46.98
37.47
30.47
24.36
18.65
12.95
7.24
0.94
‐3.07
‐10.78
Sulfur wt% 2.8
0.005
0.041
0.341
1.076
1.898
2.557
3.185
3.916
4.826
5.990
6.775
8.432
Light Ends Analysis [wt%] Ethane 0.039 Propane 0.284 i‐Butane 0.216 n‐Butane 0.637 i‐Pentane 0.696 n‐Pentane 1.245 ThefollowingstepsshowhowtoenterthedataforLightCrude.Similarstepsshouldbe
usedfortheothercrudeoils.
 SelectAssay/BlendunderComponentsintheleft‐handcolumn.ClickontheNew…
button.
Rev0.0
‐9‐
November9,2014



CallthenewcrudeassayLIGHT&chooseAssayfromtheSelectTypedrop‐downlist.
PressOK.
MakesuretheDistCurvetabisactive.MaketheAPIgravityoptionactive&enterthe
valuefromTable1.IntheDistillationCurvetypedrop‐downlistmaketheTrue
boilingpoint(weightbasis)optionactive.Inthetableenterthecumulativeyield
valuesvs.associatedtemperatures.Notethattheyieldvaluesshouldbeenteredas
percentages,scaledfrom0to100.
Nowwe’lladdinthecompositionofthelightends.MaketheLight‐Endstabactive&
theformwillchangetoallowyoutoenterthecompositions.Selectthecomponents
tobeusedtodefinethelightends(basedonthecomponentlistpreviously
specified).ChangetheFractiontypetoMass.EnterthevaluesfromTable1.Note
thattheseareintermsofmassfraction,notpercent,andarescaledfrom0to1.
Rev0.0
‐10‐
November9,2014

Nowwe’lladdintheAPIGravitydata.MaketheGravity/UOPKtabactive.Makethe
APIgravityoptionactiveintheDatatypearea.AddthedatafromTable1.Notethat
theyieldvaluesshouldbeenteredaspercentages,scaledfrom0to100.
Rev0.0
‐11‐
November9,2014

Eventhoughwecannowcharacterizethepseudocomponentsfortheflash
calculationswestillneedtoaddthesulfurdistributionsothatthesulfurcontentcan
betracked.Firstwe’llhavetoneedtodefinesulfurasaproperty;thiswillonlyhave
tobedoneonce,notforeverycrudeassay.SelectPropertySetsintheleft‐hand
column.Notethatthereareoveradozenpropertypre‐definedbyourselectingthe
Petroleumtemplate.OntheformpressNew…SettheIDasSULFUR.Onthenext
formpulldownthePhysicalPropertieslist&selectSULFUR.
Nowwewilldefinethesulfurdistributioninthecrudeoilassay.CheckforLIGHTin
theleft‐handcolumnunderComponents&Assay/Blend.Noticethereisnowa
subheadingforPropertyCurves;selectthis.OnthenextformpulldowntheProperty
NamelistandselectSULFUR.EntertheBulkvalue(i.e.,thesulfurcontentofthe
wholecrude)andthenthedistribution.
Rev0.0
‐12‐
November9,2014
AtthispointyoucouldpresstheRunbutton( ineithertheRibbonortheQuick
Accesstoolbar).NowyoucanselectResultsandseemanyofthecalculatedvalues
formtheinputdata,suchastheconversionofthelightendsanalysistovol%&mole
fractionbases,breakdownofthedistillationcurveintonarrowboilingfraction
pseudocomponents,etc.
Rev0.0
‐13‐
November9,2014
RepeatthestepsfortheMedium&HeavyCrudes.
Specifycrudeoilblend,&installintoflowsheet
Nowwe’llcreateablendofthethreecrudesandusethatasourfeedstockinthesimulation.
SelectAssay/BlendunderComponentsinthetreestructureoftheleft‐handcolumn.Press
theNew…button.CalltheblendMIXOIL&chooseBlendfromtheSelectTypedrop‐down
list.PressOK.
Rev0.0
‐14‐
November9,2014
OntheSpecificationstabselecteachcrudeoilinthepull‐downlistintheAssayIDcolumn.
SettheStdvolFractionvalueforeachto0.3333.
YoucanpresstheRunbutton&viewtheResults.
Onemorethingyoumaywanttocheck.SelectSpecificationsunderComponents.Notethat
thecrudeoilassays&theblendarelistedassingleitems.Thepseudocomponent
representationsarenotshowninthiscomponentlist.
Rev0.0
‐15‐
November9,2014
Setup&SolvetheFlowsheet
CrudeOilFeed&Preheat
WhenyouactivatetheSimulationyou’llseeablankMainFlowsheet.Wecannowstart
addingstreams&unitstorepresentourprocess.
Thefollowingaretheconditionstobesetontheoperations.
 CrudeOilFeed:100°F,300psig,101,000bpd
 Preheat‐1outlet:260°F,294psig
 Desalteroutlet:260°F,294psig,500bpdofwater
 Preheat‐2outlet:450°F,260psig
IntheModelPaletteclickontheMaterialstream.Click&drawastreamontheMain
Flowsheet.Clicka2ndtimetofinishdrawingthestream.Whenpromptednamethestream
CRUDEOIL;clickOK.
Let’sdefinethisfeedstream.Eitherdouble‐clickonthestreamintheflowsheetorchoose
CRUDEOILintheleft‐handcolumnunderStreams.Specifythetemperature&pressurefor
theFlashType;specify500°F,300psig,&101000bpdintheStatevariablessection.We
willusethemixedrepresentationoftheblendedcrudebyspecifyingtheStdvol‐Fracof
MIXOILas1.
Rev0.0
‐16‐
November9,2014
Let’saddintheequipment&otherstreamsforthepreheattrainbeforewespecifyrates&
operatingconditions.AddtwoHeatersandmaterial&heatstreamstogiveaconfiguration
asshownatthebeginningofthistopic.
WecanusetheNextbuttontostepusthroughwhatneedstobeaddedbeforewerunthe
simulation.ThefirstthingweshoulddoisdefinethewatercarriedoverfromtheDesalter.
Entertheinformationasshown.Notethatwedon’treallyknowanappropriate
temperatureforthewaterbeforeitismixedwiththecrude,rather,thetemperatureafter
themixing.Fornowspecifythetemperatureas260°F.
Rev0.0
‐17‐
November9,2014
Thenextrecommendationistospecifytheoperatingconditionsforthe1stPreheater.
Specifytheoutlettemperature&pressure.
Rev0.0
‐18‐
November9,2014
Thenextrecommendationistospecifytheoperatingconditionsforthe2ndPreheater.
Specifytheoutlettemperature&pressure.
Rev0.0
‐19‐
November9,2014
PressingNextshowsthatalloftherequiredspecificationshavebeenmade.PressOKtorun
thesimulation.AtabfortheControlPanelshouldopenup&indicatethatthesimulation
hasrunsuccessfully.
Rev0.0
‐20‐
November9,2014
Whataresomeoftheresults?Wecangetanoverviewbypostingsummaryconditionson
theflowsheet.ClickonStreamResultsintheModifytaboftheribbon.SelectTemperature,
Pressure,Volumeflowrate,&Heat/Duty.PressOK.Nowthesenumbersarepostedonthe
flowsheet;notethatthevolumetricflowrateshownintheactualvolumetricflowrate(at
theflowingtemperature&pressureconditions),notthestandardvolumetricflowrate(that
wehavebeenspecifying).
Wecanseemoredetailedresultsbyexaminingtheindividualstreams&units.Forexample,
ifweselectResultsforWETCRUDE&usetheFormatPETRO_Ethenwecanseethe
Rev0.0
‐21‐
November9,2014
calculatedtemperature(257.4°F),thestandardliquidvolumeflowrateofthecomponents
(includingthepseudocomponentsused).Atthebottomofthelistyoucanfindthetotal
volumetricflowanddistillationcurves(onadrybasis).Wecanseethesesameresults(and
more)byselectingtheStreamResultsforADDWATER.
Rev0.0
‐22‐
November9,2014
Noticethatwewouldlikethetemperatureofthecrude/watermixturetobe260°F,butthe
resultofthemixingoperationisalittlebitlower,257°F.Isthisasignificantdeviationfrom
thespecifications?Notforanythingdownstreamofthe2ndpreheater;thispreheatersets
Rev0.0
‐23‐
November9,2014
theoveralltemperature&isnotdependentontheinletconditions.However,itwillcausea
slightdifferenceinthedutyinthe2ndpreheater;havingaslightlyhigherinlettemperature
willreducethedutyrequiredtobringtheoutlettemperatureupto450°F.Therearetwo
reasonablewaystodothis:
 WecouldchangeADDWATRtoa“dummy”Heater&setthetemperatureofthe
mixture.
 WecouldadjustthetemperatureoftheWATERstreamsothatitgivestheproper
outlettemperature.Thisadjustmentcouldbedoneeithermanually(trial&error)or
usingaDesign‐Specblock.
Ifweadjusttheconditionsofthewaterstreamwefindoutthatthewaterhastobesetasa
steam/liquidmixturetogettherightpropertiesofWETCRUDE.Sincewe’renotreally
interestedintheconditionsofthisaddedwater,let’stakethedummyheaterapproach.
HighlighttheMixerADDWATR&delete.Let’sputaHeaterinitsplace;chooseablockforits
icon;calltheblockADDWATR.Right‐clickonWARMCRD1,selectReconnectDestination,&
connecttoADDWATR.DothesameforWATER.Right‐clickonWETCRUDE,selectReconnect
Source,&connecttoADDWATR.Intheleft‐handcolumnselectADWATRunderBlocks.
Specifytheoutlettemperature&pressure.PressRun.NowwhenwelookattheStream
ResultsforADDWATRweseethattheoutlettemperatureiscorrect.FromtheFlowsheet
wecanseethat,indeed,thedutyonthe2ndpreheaterhasbeenreducedslightly,from150
MMBtu/hrto148MMBtu/hr.
Rev0.0
‐24‐
November9,2014
AtmosphericDistillationColumn
ThenextstepistosetuptheAtmosphericDistillationColumn.Table4containsthe
conditions&configurationforthiscolumn.
Rev0.0
‐25‐
November9,2014
Table4.DefinitionsforAtmosphericDistillationColumn
Type Trays & Efficiencies Condenser Type Reboiler Type Pressures Temperatures Feed Locations Feed Heater Side Strippers Pumparounds Operating Parameter
50 trays. Numbering from top:
Trays 1 to 6: 80% Trays 7 to 10: 50% Trays 11 to 16: 70% Trays 17 to 30: 50% Trays 31 to 39: 30% Tray 40: 100% Trays 41 to 50: 30% Total Condenser; 130°F (approximate)
Distillate product 410°F D86 T95; 30,200 bpd (approximate) None, Direct Fired Heater
Condenser: 4 psig
Top Tray: 12 psig Bottom Tray: 22 psig Top Tray #1 250°F (estimate)
Bottom Tray #50 650°F (estimate) Crude oil to Tray #40
Stripping Steam at bottom (Tray #50) – 20,000 lb/hr @ 500°F, 150 psig Outlet @ 25 psig & 635°F
Desire is 2,500 bpd overflash (liquid rate from tray above feed, Tray #39) Kerosene Stripper
10 trays @ 30% efficiency Kerosene draw from Tray #10, vapor returned to Tray #6 Stripping steam @ bottom (Tray #10) – 2500 lb/hr @ 500°F & 150 psig Kerosene product 525°F D86 T95; 8800 bpd product (approximate) Diesel Stripper 10 trays @ 30% efficiency Diesel draw from Tray #20, vapor returned to Tray #16 Stripping steam @ bottom (Tray #10) – 2500 lb/hr @ 500°F & 150 psig Diesel product 645°F D86 T95; 10,240 bpd product (approximate) AGO Stripper 10 trays @ 30% efficiency AGO draw from Tray #30, vapor returned to Tray #26 Stripping steam @ bottom (Tray #10) – 2500 lb/hr @ 500°F & 150 psig AGO product 750°F D86 T95; 3835 bpd product (approximate) Kerosene Pumparound
Draw from Tray #10, returned to Tray #7 25,000 bpd flow, 200°F return temperature Diesel Pumparound
Draw from Tray #20, returned to Tray #17 15,000 bpd flow, 250°F return temperature AGO Pumparound
Draw from Tray #30, returned to Tray #27 10,000 bpd flow, 350°F return temperature AspenPlushasaspecificmoduleforefficientlysolvingcrudetowertypeproblems,the
PetroFracmodel(notRadFrac).OntheColumnstabselectthelistarrowforPetroFrac.Now
Rev0.0
‐26‐
November9,2014
wecanchooseaniconthatwillmostcloselyrepresentoutcolumn;chooseCDU10F,theone
withacondenser,firedheater,3pumparounds,&3sidestrippers.(Thischoiceonly
changestheicon,nottheabilitytospecifysideoperationsorthenumberofeach).Placeon
theflowsheet&nameATMCOL.Highlighttheiconontheflowsheet&grabacornerto
resize(makeitmuchbiggerthantheiconsrepresentingthepreheattrain).
Let’smakethestreamconnections.Right‐clickWARMCRD2,selectReconnectDestination,
&connecttoATMCOL.Createthefollowingadditionalstreams&connecttoATMCOL:
Rev0.0
‐27‐
November9,2014





MaterialstreamATMSTMtoMainColumnFeedconnections.
MaterialstreamsKEROSTM,DIESSTM,&AGOSTMtoStripperSteamFeed
connections.
MaterialproductstreamsNAPHTHAfromtheDistillateProductconnection,
ATMWTRfromtheCondenserWaterDecantconnection,&ATMRESIDfromthe
BottomsProductconnection.
MaterialproductstreamsKERO,DIESEL,&AGOfromtheBottomsProductfrom
Stripperconnection.
HeatstreamsQ‐ATMCfromtheCondenserHeatStreamconnection;Q‐PA1,Q‐PA2,
&Q‐PA3fromtheHeatStreamfromPumparoundconnection;
Yourflowsheetshouldhaveacolumnthatlookssomethingliketheimagebelow.Youcan
“cleanup”theimagebyclickingthecolumnicon,“grabbing”thecoloredinletoroutlet
arrowsandmovingthearrowstomakeanoverallimagethatlooksmorereasonable;see
thesecondimagebelow.Thenewimagedoesnotchangeanyconnectionsbutrathershows
amorelogicalflowpath.
Rev0.0
‐28‐
November9,2014
ClickingtheNextarrowwillstepthroughrequiredstepstosetupthisdistillationcolumn.
Thefirstthingrequiredwillbethesteamstreams:ATMSTM,KERSTM,DIESTM,&AGOSTM.
Allstreamswillbe500F&150psig;eachhastobesetupwiththepropermassflowrate.
Oncepastthesteamstreamstheconfigurationforthecolumnitselfcomesup.The
Configurationtaballowsyoutosetupthemostbasicinformationforthecolumn.Notethat
AspenPluscountsthecondenserasastage,sothetotalnumberis51(1forthecondenser
&50forthetrays).Onthisformentertheestimateforthedistillaterate(i.e.,theratefor
theunstabilizednaphtha,NAPHTHA).
Rev0.0
‐29‐
November9,2014
ClickNext.Nowwe’llsetuptheexternalfeedstothecolumn.Thecrudeoilwillgothrough
thefurnacefirst(thefurnaceiscalculatedaspartofthecolumnalgorithm);rememberthat
thecondenserisStage#1sowehavetoaddthistothetraynumberingforthefeed
location.Thesteamifintroducedtothebottomstage;remembertomarkthisasOn‐Stage
sothatthereisvaportraffictothisstage.
ClickNext.Nowwewillenterthepressures.
ClickNext.Nowwewillenterthefurnaceinformation.SelectSinglestageflashsothat
AspenPluswillperformaflashfortheoutlettemperatureofthefurnace.
Rev0.0
‐30‐
November9,2014
ClickNext.Nowwearetoenterconfigurationinformationforthepumparounds.Butfirst
let’srenamethepumparoundstomatchtheproductsections.SelectPumparoundsunder
ATMCOLintheleft‐handcolumn.Selecteachrow&clickRename.Changenamesto
PA‐KERO,PA‐DIESL,&PA‐AGO.
Nowlet’sgetbacktothePumparoundconfigurationforms.SelectPA‐KEROintheleft‐hand
column.WhenspecifyingtheDrawstage&Returnstageremembertoadd1toaccountfor
thecondenserasStage1.DothesameforPA‐DIESL&PA‐AGO.
Rev0.0
‐31‐
November9,2014
ClickNext.Nowwearetoenterconfigurationinformationforthesidestrippers.Butfirst
let’srenamethesidestripperstomatchtheproductsections.SelectStrippersunder
ATMCOLintheleft‐handcolumn.Selecteachrow&clickRename.ChangenamestoS‐KERO,
S‐DIESL,&S‐AGO.
Nowlet’sgetbacktothesidestripperconfigurationforms.SelectS‐KEROintheleft‐hand
column.WhenspecifyingtheDrawstage&Returnstageremembertoadd1toaccountfor
thecondenserasStage1.DothesameforS‐DIESL&S‐AGO.
ClickNext.Nowaformcomesuptoverifyconnectivity.We’vealreadyconnectedallofthe
materialstreams,nowwehavetoconnecttheheatstreams.Theheatstreamisconnected
tothecondenserbyvirtueofhowtheywereoriginallyconnecttoATMCOL.Butwestill
havetodothepumparoundheatstreams.SelectPA‐KEROunderPumparoundsintheleft‐
handcolumn.NowselecttheHeatStreamtab;selectthepull‐downlistforOutlet&select
oneoftheQ‐PAstreams.DothesameforPA‐DIESL&PA‐AGO.
Rev0.0
‐32‐
November9,2014
ClickNext.Wehavenowenteredenoughinformationtorunthesimulations.Howeverwe
havenotenteredthestageefficienciesnortheASTMD86specs.Let’spressOKandrunthe
simulationanyway.Itconvergesveryquickly,inabout4outer‐loopiterations.Whatdothe
resultslooklike?WecanselecttheStreamResultstabtolookatflowrates&T95results.
Notethefollowing:
 Thestreamflowrateslisted(the2ndimage)arelowerthanthespecificationsmade
onthecolumn;thatisbecausethisshowstheflowrateonadrybasis(i.e.,withthe
waterneglected)&thespecificationisonatotalbasis(withthewaterincluded).
 TheT95resultsforthedistillationcurvesareclosebutnotwhatisdesired.Wewill
wanttoadjustthedrawratestogetthedesiredT95values.
Rev0.0
‐33‐
November9,2014
We’llnowsettheT95specifications.SelectDesignSpecificationsunderATMCOLintheleft‐
handcolumn.PressNew…Youcannotnamethedesignspecs,onlynumberthem;accept
thenumberswhenpresentedintheCreateNewIDform;pressOK.Let’sfirstspecifythe
T95valueforthenaphtha.PulldowntheTypelistontheSpecificationstab;selectASTM
D86temperature(dry,liquidvolumebasis).SettheTargetvalueas410°F&theLiquid%as
95.SelecttheFeed/ProductStreamstab;highlighttheNAPHTHAstream&press>tomove
Rev0.0
‐34‐
November9,2014
ittotheSelectedStreamcolumn.SelecttheVarytab;pulldowntheTypelist&select
Distillateflowrate.
Rev0.0
‐35‐
November9,2014
SpecifyingtheT95valuesforthekerosene,diesel,&AGOstreamsisdoneinasimilar
mannerexceptwhenspecifyingwhattovary.ForthekerosenestreamselecttheVarytab;
pulldowntheTypelist&selectBottomsflowrate&thenselectS‐KEROfromtheStripper
namelist.Dosimilarspecificationsforthediesel&AGOstreams.
Wenowhavereplacedthe4flowratespecificationswiththe4T95specifications.Select
Run.Itshouldagaintakeabout4outer‐loopiterationstosolvethecolumnequations.
WecanagainlookattheproductstreamsbychoosingStreamResults.
Rev0.0
‐36‐
November9,2014
Westillhaven’taddedthestageefficienciestomodelactualtrays.Forthemaincolumn
selectEfficienciesunderATMCOLintheleft‐handcolumn.SelecttheMurphree/Vaporization
tab.Youdonothavetospecifytheefficienciesforeachindividualstagebutrathertheycan
Rev0.0
‐37‐
November9,2014
begrouped.Remembertoadd1stagetoaccountforthecondenserbeingStage#1;the
efficiencyofthecondenserwillbe100%.
Theefficienciesforthesidestrippersaredoneintheircorrespondingsection.Forthe
kerosenesidestripperselectEfficienciesunderS‐KEROintheleft‐handcolumn.Selectthe
Murphree/Vaporizationtab.Dosimilaroperationsforthediesel&AGOsidestrippers.
Wecannowrerunwillallspecifications.SelectRun.Itwilltakemoreiterationsbutshould
stillconvergeinlessthan25outer‐loopiterations.Wecanagainlookattheproduct
streamsbychoosingStreamResults.
Rev0.0
‐38‐
November9,2014
Rev0.0
‐39‐
November9,2014
DebutanizerColumn
Next,let’sdothesimplerofthetworemainingcolumns,theDebutanizerColumn(i.e.,the
NaphthaStabilizer).WewillwanttooperatetheDebutanizeratahigherpressurethanthe
AtmosphericDistillationColumn,sowewillneedapumpfortheUnstabilizedNaptha.We
willalsopreheatthefeedenteringthecolumn.Table5showstheoperatingconditionsfor
thecolumn&thefeed’spump&preheater.
Table5.DefinitionsforDebutanizerColumn
Type Feed Prep Operating Parameter Increase pressure to 250 psig; use default adiabatic efficiency for pump (75%) Preheat to 250°F; assume negligible pressure drop through exchanger Trays & Efficiencies 45 trays. Number from top. All trays 80% efficiency Condenser Type Total condenser 1.5 reflux ratio Reboiler Type Kettle reboiler Pressures Condenser: 150 psig Top Tray: 150 psig Bottom Tray: 160 psig Reboiler: 160 psig Temperature No other estimates needed Feed Locations Unstabilized Naphtha to Tray #22 Products Overhead LPGs, 5,500 bpd Stabilized naphtha from bottom PlaceaPump&Heaterontheflowsheet&definetheconnectionsasshownonthe
flowsheet.ClickNext&we’retofillinthefeedheaterinformation;setthevalueforPressure
to0tosignifyazeropressuredrop.ClickNextagain&we’llfillinthefeedpump
information;clickforDischargepressure&setthePumpefficiencyto0.75.
Rev0.0
‐40‐
November9,2014
NowwecandefinetheDebutanizer.JustlikewiththeAtmosphericDistillationColumn
we’llpickanoptionfromPetroFrac.Choosetheicononthebottomrowwithjustareboiler
&acondenser(FRACT).ConnectFEEDDEC4asafeed,createproductsstreamsLPGS&
S‐NAP,overheadwaterDEC4WTR,&heatstreamsforthecondenser&reboiler.
ClickNexttostartfillingininformationforthisDebutanizer.Remembertoadd2tothe
Numberofstagestoaccountforthecondenser&thereboiler.Alsonotethatthefeed
locationchosenisAbove‐Stage;thismeansthatliquidfromthefeedwillbeintroducedto
thestagewhereasvaporwillbeputtothestageabove(justasifafeednozzleisputinto
Rev0.0
‐41‐
November9,2014
thevaporspaceaboveatray).Remembertoaddonetothestagelocationtoaccountforthe
condenserbeingStage#1.
Thesimulationberunbutweneedtoaddthestageefficienciesfirst.SelectEfficiencies
underDEC4intheleft‐handcolumn.SelecttheMurphree/Vaporizationtab.Youdonothave
tospecifytheefficienciesforeachindividualstagebutrathertheycanbegrouped.
Remembertoadd1stagetoaccountforthecondenserbeingStage#1&1stageforthe
reboilerbeingStage#47;theefficienciesofthecondenser&reboilerwillbe100%.
Rev0.0
‐42‐
November9,2014
NowwecanclickNexttorunthesimulation.Itshouldconvergeinlessthan10outer‐loop
iterations.
VacuumDistillationColumn
Thefinalstepistodefinethefeedheater&VacuumDistillationColumn.Additionalsteam
isinjectedintotheVacuumFeedHeatertoincreasevelocity&minimizecokeformation
withintheheater.EventhoughtheVacuumColumnispackeditwillbemodeledas“trays,”
i.e.,sectionsofnon‐equilibriumstages.
PlaceaMixerontheflowsheetdownstreamfromtheAtmosphericColumn.Nextlet’splace
theVacuumDistillationColumn.JustlikewiththeAtmosphericDistillationColumnwe’ll
pickanoptionfromPetroFrac.Choosetheiconwithjustafiredheater&twopumparounds
(VACUUM1F).ConnecttheoutletfromtheMixer&asteamstreamtotheVACCOLasfeeds,
createproductsstreamsLVGO,HVGO,&SLOPWAXasSideProductsfromMainColumn,
overheadvaporVACOVHD,&heatstreamsforthetwopumparounds.
Rev0.0
‐43‐
November9,2014
Table6.DefinitionsforVacuumDistillationColumn
Type Operating Parameter
“Trays” & Efficiencies 14 trays. Numbering from top:
Tray 1: 100% Trays 2 to 11: 50% Tray 12: 100% Trays 13 to 14: 30% Condenser Type No condenser, LVGO pumparound liquid return to top stage
Reboiler Type None, Direct Fired Heater
Pressures Top Tray: 50 mmHg
Bottom Tray: 62 mmHg Temperatures Top 180°F (controlled by top LVGO pumparound)
Feed Locations Crude oil to Tray #12
Stripping Steam at bottom (Tray #14) – 20,000 lb/hr @ 500°F, 150 psig Feed Heater 20,000 lb/hr steam injected into heater coils with the Atmospheric Resid feedstock (500°F & 150 psig) Outlet @ 180 mmHg & 760°F; would like 3,000 bpd excess wash liquid (liquid rate from tray above feed, #11) Pumparounds LVGO Pumparound
Draw from Tray #4, returned to Tray #1 22,300 bpd flow, outlet temperature adjusted to control top temperature of tower; approximately 85°F, 40 MMBtu/hr cooling HVGO Pumparound
Draw from Tray #8, returned to Tray #5 50,000 bpd flow, 150°F cooling approximately 400°F, 40 MMBtu/hr cooling Products LVGO from Tray #4; 915°F D1160 T95; 5,000 bpd (approximate) HVGO from Tray #8, 1050°F D1160 T95; 21,000 bpd (approximate) Slop Wax from Tray #11, 1,000 bpd Vacuum resid from bottom FirstdefinethesteamstreamgoingtotheVacuumHeaterCoils.SelectCOILSTMunder
STREAMSintheleft‐handcolumn.Dothesameforthesteamstreamgoingtothebottomof
theVacuumDistillationColumn,VACSTM
Rev0.0
‐44‐
November9,2014
Let’sconfiguretheVacuumDistillationColumnitself.SelectVACCOLunderBlocksinthe
left‐handcolumn.Eventhoughthecolumnwillbepackedwe’llmodelitwithasetofnon‐
equilibriumstages.OntheConfigurationtabpicktheCondenseroptionNone‐Top
pumparound.OntheStreamstabdenotethatVACFEEDgoesthroughafiredheaterbefore
goingtoStage#12&theVACSTMgoesdirectlyOn‐Stageto#14.Setthetop&bottom
pressuresonthePressuretab.OntheFurnacetabspecifytheFurnacetypeasSinglestage
flashwithliquidrunback&settheoutlettemperature&pressure.
Rev0.0
‐45‐
November9,2014
Rev0.0
‐46‐
November9,2014
Nowlet’ssetupthepumparounds.ChangethenamestoPA‐LVGO&PA‐HVGO.Setdraw
rates&conditionsontheSpecificationstab.Let’sapplytheapproximatespecsasHeatduty
specs(sincethesearethemostlikelytoconverge).NotethattheHeatdutyvaluesare
specifiedasanegativenumberssincetheyrepresentcooling(i.e.,heatremoval).Connect
theappropriateheatstreamontheHeatStreamstab.
Rev0.0
‐47‐
November9,2014
Let’sspecifythestageefficiencies.SelectEfficienciesunderVACCOLintheleft‐handcolumn.
SelecttheMurphree/Vaporizationtab.Youdonothavetospecifytheefficienciesforeach
individualstagebutrathertheycanbegrouped.
Rev0.0
‐48‐
November9,2014
Toaidintheconvergenceofthecolumnlet’saddacoupletemperatureestimates.Clickon
theEstimatesitemintheleft‐handcolumn.Specifyvaluesfortrays#1,#2,&#14.
Let’sapplythefirstdesignspecbeforetryingtorunthesimulation,theoneforthetop
temperature.Thisisachievedbyadjustingtheoperationofthetoppumparound,PA‐LVGO.
ClickonDesignSpecificationsintheleft‐handcolumn,clickNew,andselectOKforthe
defaultname1.ThespecTypeisStagetemperatureforStage1;we’llVarythePumparound
dutyforPA‐LVGO(sincethisisthespecweappliedtothispumparound).
Rev0.0
‐49‐
November9,2014
Runthesimulation.TheVacuumColumnshouldconvergeinabout10iterations.
Wehavenotappliedallofthedesignspecs,butlet’sseehowclosewecometothedesired
performance.WearemostinterestedintheD1160T95valuesfortheLVGO&HVGOas
wellastherunbackliquidfromthesectionaboutthefeedtray(i.e.,theliquidratefrom
Tray#11).NotethattheD1160values(correctedto1atm)above50%aretheTBPvalues.
TheT95valuescanbefoundwhenselectedtheStreamResultsintheleft‐handcolumn;the
TBPvaluesare768.3°FfortheLVGO&913.9°FfortheHVGO.Theliquidrunbacktothe
feedtraycanbecalculatedfromtheinformationintheProfilestable.Normallythenetflow
ofliquidfromonetraytotheonebelowwouldbetheamountintheLiquidflowcolumn
minustheamountintheLiquidproductcolumn.However,forthefeedheaterchosen,allof
thenetliquidisfedbacktothefrontoftheheater&isconsidered“liquidproduct,”too.So,
thenetliquidisreallytheamountintheLiquidproductcolumnminustheSlopWaxrate
produced;herethisis186,800bpd.
Rev0.0
‐50‐
November9,2014
ToincreasetheT95valueofasidedrawwewouldnormallyincreasethedrawrate.We
havetobecareful,though,nottoexceedthevaluesgoingintoeachsection(andcausethat
sectiontodryup).Let’saddresstheHVGOfirst.Createanewdesignspec&varytheHVGO
drawratetoachievethis.Rerunthesimulation;itshouldconvergeinlessthan20
iterations.Nowwehavewithdrawn30,676bpdHVGOtomakethisT95spec.Theliquid
runbackhasreducedconsiderably,nowdownto3,050bpd.
Rev0.0
‐51‐
November9,2014
Nowlet’slookattheLVGOresults.For5,000bpdLVGOratetheD1160T95valueistoo
low.SincetheT95valueistoolow,wewillhavetoincreasetheLVGOdrawratetotryto
meetthisspec.However,thereisonly3,518bpdrunbackabovethefeedtray,sowe
normallythinkthatcan’traisetherateabovethisamount.However,wecanactuallyraiseit
considerably&notdryupthetopoftheVacuumColumn.NotethatifweraisetheLVGO
specto4,000bpdwecandothisandactuallyincreasetherunback.How?Becausethe
HVGOratedecreasesbymorethan3,000bpdtokeepitsT95spec.Solet’sapplytheLVGO
T95spec;nowwe’vemadebothT95specswithoutdryingupthetopoftheVacuum
Column.
Thefinalspecthatweneedtoachieveistheliquidratefromabovethefeedtray.The
currentrateis6,776bpd,higherthannecessary.Wecanreducethisratebyreducingthe
feedheater’soutlettemperature(whichwillreducetheamountofthefeedvaporized).We
canadjustthefeedheatertemperaturemanuallyto739.5°Fandgetaliquidrunbackrateof
2,990bpd(justalittlebittoolow).Canweadjustthisautomaticallytodeterminetheactual
temperature?Wecouldaddadesignspectomodifythefurnacetemperaturemakethe
liquidratefromTray#11;inpastexperiencethiswilltendtocrashtheprogram.Instead
wewillusethebuilt‐infacilitytomodifythefurnace’soutletconditionsbyspecifyingthe
fractionaloverflashinthecolumn.Sincethetotalstandardflowtothecolumnis53,632
bpdthen3,000bpdoverflashmeansafractionalvalueof0.05594.Makingthisspecification
willgivethecorrectoverflashvalue&resultsinafurnaceoutlettemperatureof739.56°F.
Rev0.0
‐52‐
November9,2014
Theresultsofallofthesestepsaresummarizedinthefollowingtable.
VacuumColumnResultsWhenApplyingDifferentSpecs
LVGO Rate [bbl/day] 1,000  1,000  4,000  16,487 16,835 16,808 LVGO D1160 T95 [°F] 768.4 797.1 825.9 915  915  915  HVGO Rate [bbl/day] 21,000 
30,676
27,220
13,855
13,185
13,212
HVGO D1160 T95 [°F] 924.4
1050 
1050 
1050 
1050 
1050 
Slop Was Rate [bbl/day] 1,000  1,000  1,000  1,000  1,000  1,000  Runback from Tray #11 [bbl/day] 186,810
3,050
3,562
6,776
2,990
3,000
Rev0.0
‐53‐
November9,2014