cost
DESCRIPTION
CostTRANSCRIPT
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CAPITALCOSTESTIMATION
Dr.M.Fadhil A.Wahab
Dr.MuhammadAbbas AhmadZaini
SKF4153 PLANTDESIGN
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=
baseIICostBaseCost
CostIndexes
9 Equipmentcostisobtainedfromcharts,equationsorquotesfromvendors,andonlyvalidforacertainperiodoftime.
9 Thecostchanges(increases)fromyeartoyearprimarilyduetoinflation.
9 ToestimatepurchaseCost,CP atalaterdate,9 TheChemicalEngineering(CE)PlantCostIndex,TheMarshall&Swift
(MS)EquipmentCostIndex,TheNelsonFarrar(NF)Refinery
ConstructionCostIndex,TheEngineeringNewsRecord(ENR)
ConstructionCostIndex.
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9 Onetimeexpensefordesign,constructionandstartupforneworarevampofanexistingplant.
9 Grassrootsplantsvs.Plantexpansions.9 ComponentsofTCI: CTBM:TotalBareModuleCost CDPI:DirectPermanentInvestment CTDC:TotalDepreciableCapital CTPI:TotalPermanentInvestment CW:WorkingCapitalInvestment
TotalCapitalInvestment(TCI)
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Methods(Levelsofaccuracy), Orderofmagnitudeestimate( 50%) basedonproductionrateand
majorequipmentsasdeterminefrombenchscalelaboratorydata.
Studyestimate( 35%) basedonapreliminaryprocessdesign. Preliminaryestimate( 20%) basedondetailedprocessdesign
studiesleadingtoanoptimizedprocessdesign.
Definitiveestimate basedonadetailedplantdesign,includingdetaileddrawingsandcostestimates,sufficienttoapplycostaccounting.
EstimationofTCI
- Toknowwhetheraprocessisworthpursuingornot? Suitableforlowpressureprocess(
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UsingsixtenthsrulecomputeproductionratefactorFPR:
FPR =Capacity2Capacityb
m
= Main product flowrate,lb / yr10,000,000
0.6
Step1ofMETHOD1
Step2ofMETHOD1
CalculateindividualmodulecostCMforcompressors,blowers,separators(distillation,absorber,etc.),reactor,butnotforpump,flash,refluxdrumandheatexchanger.
160000$100
100,, 25.0
>= psiaifpsiapressuredesignFFC MPRM
FMismaterialfactor;Carbonsteel(FM=1.0),Copper(FM=1.2),Stainlesssteel(FM=2.0),NickelAlloy(FM=2.5),Titaniumclad(FM=3.0).
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CalculatetotalbaremoduleinvestmentCTBMforcurrentyear,
FPIisfactortoaccountforpiping,instrumentation,automaticcontrolaswellasindirectcosts.Forsolidhandling(FPI=1.85),solid&fluids(FPI=2.0)andforfluidshandling(FPI=2.15).
= M
baseMS
MSPITBM CI
IFC,
Step3ofMETHOD1
Step4ofMETHOD1 CalculatedirectpermanentinvestmentCDPI
( ) TBMDPI CFFC 211 ++=F1 andF2 arefactorstoaccountsitepreparation,servicefacilities,utilityplants.Foroutdoorconstruction(F1=0.15),Indoor&outdoor(F1=0.4)andindooronly(F1=0.8).Forminoradditiontoexistingfacilities(F2=0.10),majoradditiontoexistingfacilities(F2=0.3)andforgrassrootsplant(F2=0.8).
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CalculatetotalpermanentinvestmentCTPI Add40%tocoverforcontingenciesandanother10%forland,
royaltiesandstartup(totalof50%,thusmultiplyby1.5).
DPITPI CC 5.1= CalculatetotalcapitalinvestmentCTCI Add15%tothetotalpermanentinvestmentCTPI
TPITCI CC 15.1 =
Step5ofMETHOD1
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HerethemethodisbasedonoverallfactormethodofLang(1947,1948).
ReferTable22.16forLangfactorsofTPIandCPI,fL,TPI andfL,TCI,respectively.
Purchasecost,CP foraparticularbaseyear(Ib,i) shouldalreadybeknown.
Thepurchasecostofequipmentwasbasedonyear1977,andthecorrespondingMSindexforthatyearis514.
METHOD2:StudyEstimate
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Prepareanequipmentlistincludingtheirpurchasecostforaparticularbaseyear.
Updatetothecurrentcostindex(II)andsumtheupdatedpurchasecost.
Multiplyby1.05toaccountfordeliverycosttotheplantsite.
SummaryofstepsinMethod2
CTPI
= 1.05 fL , TPI
II
Ib, i
i CP, i
CTCI
= 1.05 fL , TCI
II
Ib, i
i CP, i
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9 BasedonIndividualFactorsMethodofGuthrie (1969,1974).9 Bestcarriedoutafter; Optimalprocessdesign, CompleteM&Ebalances,Equipmentsizinganddecisionon
materialsofconstruction,
ProcesscontrolconfigurationdevelopedasinP&ID.
METHOD3:PreliminaryEstimate
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Prepareanequipmentlistincludingtheirpurchasecostforaparticularbaseyear.
Updatetothecurrentcostindex(I). Thepurchasecostisbasedonnearambientdesignpressure,
carbonsteelmaterialandabasedesign.
Steps1&2ofMETHOD3
Step3ofMETHOD3
Foreachpieceofequipment,determinebaremodulecost(CBM)usingbaremodulefactors(FBM)andapplyappropriate
factorsfordesign(Fd),pressure(FP)andmaterial(Fm).
CBM
= CP, b
II
b
FBM + FdFPFM 1( )[ ]
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ObtainedthetotalbaremodulecostCTBM.
CTBM
= CBM
CalculatetotalpermanentinvestmentCTPI,(note:notincludingstartupandroyalties)
CTPI
= 1.18(CTBM
+ Csite
+ Cbuilding
+ Coffsite facilities
)
AddworkingcapitaltocalculatetotalcapitalinvestmentCTCI
CTCI
= CTPI
+ CWC
Steps4&5ofMETHOD3
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Table22.19givessourcesofwidelyusedequipmentcostdataandthecorrespondingbasecostindex.
Usuallypresentedintheformofgraphsand/orequations. CouldbegeneratedusingAspenIcarus ProcessEvaluator(Aspen
IPE).
AspenIPE:moreaccurate,consistentandperiodicallyupdated.
PurchaseCost,Cp
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9 Determinesizefactor,S=Q(H)0.5
9 QisflowrateingpmandHisthepumpheadinft
9 Calculatebasef.o.b.purchasecost,
CB=exp{9.71710.6019[ln(S)]+0.0519[ln(S)]2}
9 Purchasecost(CB hasalreadytakenintoaccount)ofasinglestage,3600rpm,verticalsplitcase(VSC),andmadeofcast
ironcentrifugalpumpforSbetween400and100000canbe
estimatedfromFigure22.3.
Cp ofCentrifugalPump
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9 Forotherspecifications,purchasecostofcentrifugalpump,
Cp=FTFMCB
9 FM ismaterialfactor fromTable22.21.
9 FT ispumptypefactor fromTable22.20.
9 Thispricedoesnotincludeelectricmotor.
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9 Basef.o.b.purchasecostdataofHEXarecorrelatedintermsofsurfacearea.
9 Fig.22.10isonlyvalidforcarbonsteeltubes, in.or1in.OD,wallthicknessoftubeis16BWG(BirminghamWireGage),20ftlong,
squareortriangularpitch,carbonsteelwithshellsidepressureup
to100psig,andsurfaceareabetween150to12000ft2.
9 Forotherspecifications,useEquation22.43,andCB ofparticulardesignfromEquations22.3922.42.
Cp ofShell&TubeHEX
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9 Equation22.43;
Cp=FPFMFLCB
9 FL istubelengthcorrectionfactor (seepage571)9 FM ismaterialfactor (Equation22.44andTable22.25)9 FP ispressurefactor (Equation22.45),Pinpsig.9 Readalso onpurchasecostsfordoublepipeHEXandfired
heater.
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Sizefactor=Weight(lb) Forotherspecifications,useEquation22.52.
Cp=FMCV+CPL
Obtaincostofemptyvessels,CV;inEquations22.53(horizontal),22.54(vertical)and22.57(towers).
Additionalcostforplatformandladder,CPL;inEquations22.55(Horizontal),22.56(Vertical)and22.58(towers).
Useappropriateunitsfortheequations ValuesofFM aregiveninTable22.26.
Cp ofPressurevesselandTowers
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W=(Di+tS)(L+0.8Di)tS
isdensityofcarbonsteel. tS isthicknessofshellandellipticalheads.
9 Athighinternalpressure(operatingpressure);useEquation22.60,wheretS =tP.
9Minimumwallthicknessatlowpressuresaregivenatpage575.
Effectofwindandearthquakeonaverticalvessel/tower,useEquations22.60and22.62.tS =tV =tP+tW
Atlowinternalpressure(vacuum),useEquations22.6322.65.tS =tV =tE+tEC.
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Addcostofinstalledtrays(inclusivealldowncomers),CT tocostofvessel.
Cp=FMCV+CPL+CT
CT=NTFNTFTTFTMCBT
Basecost,CBT(CE394,year2000)isgivenbyEquation22.67. NT istraynumber,FNT isgivenbyEquation22.68,FTT istraytype
factor,FTM istraymaterialfactor,seepage577.
ForPackedcolumn,selflearnfrompage578.
Cp ofTrayandPackedTower
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References
G.D.Ulrich,ProcessPlantDesignandEconomics,JohnWiley,1984. L.T.Biegler,I.E.Grossman,A.W.Westerberg,SystematicMethodsof
ChemicalProcessDesign,PrenticeHall,1997. Monograph,ProcessDesignandSynthesis,Universiti Teknologi Malaysia,
2006/07 W.D.Seider,J.D.Seider,D.R.Lewin,ProductandProcessDesign
Principles:Synthesis,AnalysisandEvaluation,JohnWileyandSons,Inc.,2010.