The UniversiTy of Texas aT aUsTin • PeTroleUm exTension service

Plant Processingof Natural GasPlant Processingof Natural Gas

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Table ofContents

FIGURES viTABLES viiiFOREWORD ixACKNOWLEDGMENTS xiABOUT THE AUTHORS xiiiCHAPTER 1. Fundamentals 1

Fluid Properties 1Temperature 2Pressure3GravityandMiscibility 3Solubility 4

The Ideal Gas Law 4LiquidPhase 5VaporPressure 5BoilingPointandFreezingPoint 6

Hydrates 7Comparing Physical Properties 8Composition 10Heat Energy 10

HeatingValue 12Combustion 12

Flammability 13Applications 13

FlowDiagrams 14References 21

CHAPTER 2. Feed Gas Receiving and Condensate Stabilization 23Treating and Processing 23Design Basis and Specifications for Treatment Units 26

FeedGasBasis 26ProductSpecifications 27

Equipment Selection and Design 28PigReceivers 28SlugCatchers 30CondensateStabilizers 32CondensateStabilizerReboilers 32StabilizerOverheadCompressors 32GasandLiquidHeaters 32

References 33CHAPTER 3. Dew-Point Control and Refrigeration Systems 35

Process Descriptions 35Cost Estimate 35

SilicaGelProcess 36Glycol/PropaneSystem 37Glycol/J-TValveCoolingProcess 38ComparisonofDew-PointProcesses 40UnitSpecifications 40

The Refrigeration System 41Economizers 42Chillers 44PossibleProblems 44Multiple-StageRefrigeration 46

References 50

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CHAPTER 4. Hydrocarbon Treating 51Gas-Treating Processes 51Chemical Reaction 51

Amine-BasedSolvents 52Nonamine-BasedProcesses 57

Physical Absorption Processes 58Selexol® 59PropyleneCarbonateProcess 59Rectisol®Process 60

Mixed Chemical/Physical Absorption 60Sulfinol®Process 60

Adsorption on a Solid 61MolecularSieveProcess 61ActivatedCarbonProcess 62

Membrane Processes 62General Operating Considerations for Gas Treating 65

InletSeparation 65Foaming 65Filtration65Corrosion 65

References 66CHAPTER 5. Sulfur Recovery and Claus Off-Gas Treating 67

Sulfur Recovery 67ThermalProcess 67CatalyticRecovery 68

Claus Off-Gas Treating 70SCOTProcess 70

References 72CHAPTER 6. Dehydration and Mercury Removal 73

Dehydration 73InhibitorInjection 76

Dehydration Methods 80LiquidDesiccants 80SolidDesiccants 84DesignIssues 88

Mercury Removal Unit (MRU) 90DesignBasisandSpecifications 92DesignConsiderations 94EquipmentSelectionandDesign 95CaseStudy 95

References 96CHAPTER 7. NGL Recovery—Lean-Oil Absorption 97

Lean-Oil Absorption 98TheRecoverySystem 98Absorption 99WhyAbsorbersWork 99Presaturation 100PotentialProblems 102

The Rejection System 104HotRich-OilFlashTank 104Rich-OilDemethanizer 105PossibleProblems 107

The Separation System 108TheStill108OilPurification 109PossibleProblems 110

References 111

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CHAPTER 8. NGL Recovery—Cryogenic 113Typical Applications 115

TurboexpanderProcess 115Propane-RecoveryProcess 120Ethane-RecoveryProcess 121

Turboexpanders 122Cyrogenics 127References 130

CHAPTER 9. Fractionation and Liquid Treating 131Fractionation 131Packed Columns 134NGL Fractionation Plants 134

Deethanizer(DeC2)Column 136Depropanizer(DeC3)Column 137Debutanizer(DeC4)Column 137Deisobutanizer(DIB)orButaneSplitterColumn 137

Product Specifications 138Monitoring Fractionation Plant Operation 139Possible Operating Problems 140NGL Product Treating 141

Liquid—LiquidTreating 141Liquid—SolidTreating 143

References 143CHAPTER 10. Nitrogen Rejection Unit (NRU) 145

Nitrogen Rejection 145NRU Process Selection 145

PressureSwingAdsorption(PSA) 145CryogenicAbsorption 145Membranes 146CryogenicDistillation 146

Cryogenic NRU Processes 146Pretreatment 147Chilling 148CryogenicDistillation 148Recompression 148

NRU Processes 149References 152

APPENDIX. Figure and Table Credits 153GLOSSARY 159INDEX 183

Table of Contents

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About the Authors

Dr.DougElliot hasmore than 40yearsexperience in theoilandgasbusiness,devotedtothedesign,technologydevelopment, anddirectionof industrialresearch.DougiscurrentlyPresident,COOandcofounder(withBechtelCorporation)

ofIPSILLC,acompanyformedin1986todeveloptechnologyandpro-videconceptualdesignservicestooilandgasproducingandengineering,procurement,andconstructioncompanies.

PriortoIPSI,DougwasVicePresidentofOilandGaswithDavyMcKeeInternational.DougstartedhiscareerwithMcDermottHudsonEngineering in the early 1970s following apostdoctoral research as-signmentunderProfessorRikiKobayashiatRiceUniversity,wherehedevelopedaninterestinoilandgasthermophysicalpropertiesresearchanditsapplication.

Doughasauthoredor coauthoredover65 technicalpublicationsplus12patents.HeservedasamemberoftheGasProcessorsAssociationResearchSteeringCommitteefrom1972to2001andasChairmanoftheGPSA(GasProcessorsSuppliersAssociation)DataBookCommitteeonPhysicalProperties.DougservedasChairmanoftheSouthTexasSectionandDirectorof theFuelsandPetrochemicalDivisionof theAmericanInstituteofChemicalEngineers;andiscurrentlyamemberofthePETEXAdvisoryBoard.HeholdsaB.S.degreefromOregonStateUniversityandM.S.andPh.D.degreesfromtheUniversityofHouston,allinchemicalengineering.

DougisaBechtelFellowandaFellowoftheAmericanInstituteofChemicalEngineers.

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J.C.Kuo (ChenChuan J.Kuo) is a34-yearveteranof thegasprocess-ing,gastreating,andliquefiednaturalgas(LNG) industry.As a senior advisor forChevron’sEnergyTechnologyCompany,he has served as the ProcessManager/

ProcessLeadformanyprojects,includingtheWheatstoneLNG,GorgonLNG,DeltaCaribeLNG,CasotteLanding,andSabinePassLNGterminalprojects.HehasalsoservedasthetechnicalprocessreviewerforAngola,Olokola,Algeria,andStockmanLNGprojects.BeforeworkingatChev-ron, J.C.was theTechnologyManager for IPSI, anaffiliateofBechtel,andservedastheProcessManager/ProcessLeadforthePemexCatarelloffshoreproject,theEgyptianLNG(Idku)trains1and2,ChinaShellNanHai,ChevronVenicegasplantde-bottleneck,TunisiaNRU,andAustralianSANTOSprojects.

J.C.isafrequentspeakerandpresenteratinternationalconferencessuchasfortheAmericanInstituteofChemicalEngineers,gasprocessingandtreatingconferences,andtheLNGSummit.HehascontributedtogasprocessingandLNG technology improvements throughapatent,abook,andmanypapers.Hehasalsoservedasco-chairoftheAIChELNGsessionsforthetopicalconferencesonnaturalgasutilization.HeisamemberofthesteeringcommitteefortheNorthAmericanLNGSummit.

HisdegreesincludeaB.S.fromChungYuanChristianUniversity,Taiwan,andanM.S.fromtheUniversityofHouston,bothinChemicalEngineering;andanM.S.inEnvironmentalEngineeringfromSouthernIllinoisUniversity.HeisaregisteredProfessionalEngineerinTexasandamemberofAIChE.Heisthepresidentofthe99PowerQiQongTexasdivisions.

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Dr.PervaizNasirhasmore than27years experience in theoil andgasbusiness.HeiscurrentlytheRegionalMan-agerGas/LiquidTreatingandSulfurPro-cesses,Americas,atShellGlobalSolutions.

PervaizstartedhiscareeratShellDe-velopmentCompanyin1981inresearchanddevelopmentandtechnicalsupport,mostlyrelatedtooilandgasprocessing.In1986,hemovedintolicensingandprocessdesignofShellGas/LiquidTreatingtechnologies.AsamemberofShellMidstreamfrom1991through1999,Pervaizwasresponsiblefortheoperationssupportandoptimizationofexistinggasplantsandthedevelopmentandstartupofnewgasprocessingfacilities.HethenjoinedEnterpriseProductsCompanyasDirectorofTechnology.AtEnterprise,Pervaizwasresponsiblefortheevaluationofnewbusinessventures/technologies ingasprocessing, liquefiednatrualgas (LNG),petrochemicals,etc.HereturnedtoShellGlobalSolutionsin2006.

PervaizholdsaB.S.fromMiddleEastTechnicalUniversity(Ankara),anM.S.fromUniversityofAlberta(Edmonton),andaPh.D.fromRiceUniversity(Houston),allinchemicalengineering.HeservedontheGasProcessorsAssociation(GPA)PhaseEquilibriaResearchSteeringCom-mittee from1983 through1990and iscurrentlyamemberof theGPALNGCommittee.Pervaizhasauthoredorcoauthoredover17externaltechnicalpublications.

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1 Fundamentals

Natural gasiscolorless,shapeless,andodorlessinitspureform.Itisafos-silfuelconsistingprimarilyofmethanewithquantitiesofethane,propane,butane,pentane, carbondioxide, nitrogen,helium, andhydrogen sulfide.Naturalgasiscombustible,givesoffagreatdealofenergy,iscleanburning,andemitslowlevelsofbyproductsintotheair.Itisanimportantsourceofconsumerenergyusedinhomestogenerateelectricity.

Thepetroleum industry classifiesnaturalgasby its relationship tocrudeoil in theunderground reservoir.Associated gas is the termusedfornaturalgasthatisincontactwithcrudeoilinthereservoir.Theassociatedgasmightbeagas capoverthecrudeoilinareservoirorasolutionofgasandoil.Nonassociated gasisfoundinagasphaseinreservoirswithoutcrudeoil.

Whetherassociatedornonassociated,gas production streams arehighlyvariableandcancontainawiderangeofhydrocarbonandnonhydrocarboncomponents.Thesestreamsmightincludevariousmixturesofliquidsandgasesaswellassolidmaterials.Thereareusuallysomenonhydrocarboncomponentsincludingnitrogen,helium,carbondioxide,hydrogensulfide,andwatervaporpresentinthestream.Traceamountsofothercomponents,suchasmercury,mightalsobepresent.

Naturalgasprocessingplantsusephysicalandchemicalprocessestoseparateandrecovervaluablehydrocarbonfluidsfromagasstream.Intheprocessingplant,allthepipes,containmentvessels,steamlines,tanks,pumps,compressors,towers,andinstrumentscontainagasorliquidundergoingsomekindoftreatmentprocess.

Duringtheprocessing,thenonhydrocarboncontaminantsmustbehan-dledproperlybecausetheyaffectgasbehaviorduringtreatment,impairtheefficiencyofprocessingoperations,orcandamagetheprocessingequipment.Forexample,thecontaminant,liquidmercury,weakensandbondswiththealuminumheat exchangersusedtoproducesupercooledfluids.Ifmercuryisnotremovedfromthegasearlyintheprocessingphase,itliquefiesandcol-lectsontheexchanger’ssurfaces,eventuallydestroyingtheheatexchangers.

FLUID PROPERTIES

Whenthereisapipe,asteamline,atank,apump,acompressor,atower,aninstrument,orevenafilledsamplecontainerinagasplant,italmostalwayscontainsafluid.

What isafluid?Afluidcanbeagas,a liquid,orasolid.Afluid isdefinedasanysubstancethatflowsfreelyunlessrestrictedorcontainedbyabarrier.Withouttheabilitytoassumeashapeofitsown,afluidassumestheshapeofthecontainerintowhichitisplaced.Bothgasesandliquidsareclassifiedasfluids.

Naturalgas treatment isbasedonthereactionsofreservoirfluids inphysicalandchemicalprocesses.Eachfluidhasauniquesetofpropertiesincludinggravity, solubility,andflammabilitycontrolling its response togivenstimuli.Agasprocessingplantoperatormustdeterminethespecificpropertiesandconditionsofitssourceofoilfieldfluids,orfeedstock,becauseeachoneisdifferent.Problemsthatoccurduringgasprocessingcomefromafundamentalmisunderstandingofthespecificfluidpropertiesorthephysicalandchemicallawsthatdeterminefluidbehavior.

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2 Feed Gas Receiving and Condensate Stabilization

TREATING AND PROCESSING

Plantunitconfigurationsvarydependingonthetypeofcomponentsofthefeedgasandthefinalproductsdesiredforconsumeruse(fig.2.1).

Figure 2.1 Gas processing plant

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Feedgasfromvariousgasfieldsentersthegasplantthroughpipelinesandgoesthroughseveralunitsoftreatingandprocessing,asshowninfigure2.2.Themainunitsperformthefollowingfunctions:

• Removeoilandcondensates• Removewater• Separatethenaturalgasliquidsfromthenaturalgas• Removesulfurandcarbondioxide• Removeimpuritiessuchasmercury,oxygen,andBETX(benzene,

ethylbenzene,toluene,andxylenes)

Thefirsttreatingunitisthefeedgas-receivingsystemandtheconden-satestabilizationsystem.Condensateisalighthydrocarbonliquidobtainedbycondensationofhydrocarbonvapors.Itconsistsofvaryingproportionsofpropanebutanes,pentanes,andheaviercomponentswithlittleornomethaneorethane.Thefeedgasreceivingsystemseparatesthefeedgasintogases,aqueousliquid,andhydrocarbonliquidforfurtherprocessingatplantunitsdownstream(fig.2.3).

Thecondensatestabilizationsystemremovesthelightcomponentssuchasmethane,ethane,andpropane,dissolvedinthehydrocarbonliquidfromthefeedgasreceptionsystem(fig.2.4).Hydrocarbonliquidnormallycon-tainsalargeamountofdissolvedlightcomponentsbecauseofhighpipelinepressures.Theselightcomponentsneedtoberemovedtomeetcondensateproductandotherdownstream processingrequirements.

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3 Dew-PointControl andRefrigerationSystems

PROCESS DESCRIPTIONS

Rawgascomesfromproductionfieldsthroughthepipelinestothefeedgasreceivingunitandcondensatestabilizationunit.Therawgasthenflowstothegas-treatingunitandthentoadew-pointcontrolandrefrigerationunitoranatural gas liquid (NGL)recoveryunit.Anexportcompressionsystemissometimesusedafterthedew-pointcontrolunittopressurizethegastotherequirementsofthe pipeline grid.Finally,thegasissenttotheconsumersthroughapipelinegrid.

Adew-pointcontrolunithelpstopreventliquidcondensationinthepipelinegridundervariouspressuresandtemperatureconditions.Therearetwokindsofdew-pointcontrolrequired:awater dew-point controlandahydrocarbon dew-point control.Inwaterdew-pointcontrol,thereareseveraldehydration,orwaterremoval,methodsavailable,includingthesilica gel,glycol,andmolecular sieve.Hydrocarbondew-pointcontrolalsohasvariousmethodsavailable including refrigerated low-temperature separation (LTS),expander,Joule-Thomson (J-T), andsilicagel.Companiesmightuseglycolgasdehydrationforwaterdew-pointcontrolandarefrigerationcoolingsystemforhydrocarbondew-pointcontrol.MoreexplanationofgasdehydrationisgiveninChapter6.

Thepurposeofarefrigeration systemistoremoveheatfromthefeedstreaminaheatexchanger.Heatexchangersarereferredtoas evaporatorsorchillers andprovidetherequiredcoolinglevel forvariousgasprocess-ingapplications.Refrigerationsystemsuserefrigerant,calledworking fluid.Workingfluidisselectedbasedupontemperaturerequirements,availability,economics,andpreviousexperience.Theavailabilityofethaneandpropaneonhandatnaturalgasprocessingplantsmakesthesegasestheprimechoiceasworkingfluids.Ingasplants,propaneisnormallythepreferredrefrigerant.

COST ESTIMATE

Dew-pointdepressionisdefinedasthedifferenceindegreesbetweenthefeedgastemperatureandthedewpointofafluid.Thedew-pointdepressiondif-ferenceindegreesdeterminesthebestprocesstousefordew-pointcontrol.

Depending on the amount of dew-point depression required, aneconomicevaluationisdonetocompareinstallationcostsandoperatingcostsforthevariousprocesses.Usinganaverage80°F(45°C)dew-pointdepressionrequirement,thereareseveralprocessesavailableforthedew-pointcontrol.Threeofthemostwidelyusedprocessoptionsarethesilicagelprocess, theglycol/propane refrigerationprocess, and theglycol/J-Tvalvecoolingprocess.

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4 HydrocarbonTreating

GAS-TREATING PROCESSES

Hydrocarbonstreams,bothgaseousandliquid,mightcontaincontaminantssuchasH2SandCO2thatmustberemovedbeforefurtherprocessingandmarketing.RemovalofH2S,CO2,andothersulfurcompounds,commonlycalledacid gases,isnormallyreferredtoashydrocarbontreating orsweetening.

Treatedgasregulationsandspecificationsarestringentregardingre-sidualH2Sandothersulfurspecies.TypicalU.S.salesgascontractsrestrictthefollowing:

H2S <0.25grains/100scf(about4ppmv)Totalsulfurcompounds <5grains/100scf(about80ppmw)CO2 <2%mole

Acidgascomponentscanberemovedfromasourgasstreamby:• chemicalreactionusingliquidsorsolids;• physicalabsorptioninliquids;• adsorptiononsolids;• diffusionthroughmembranes.

Theacidgasremovalprocessescanbenonregenerativeorregenerative. Thenonregenerativeprocessesaresuitableonlywhentraceamountsofcon-taminantsmustberemovedand/orveryhighpurityoftreatedgasisdesired.NonregenerativeprocessesbecometoocostlywhentheH2Stoberemovedexceedsabout1tonperday.ExamplesofnonregenerabletreatingprocessesareSulfaTreat®andChemsweet®,bothmarketedbyC.E.Natco.

Regenerativeprocessesaremoreeconomicalforremovinglargerquan-titiesofcontaminants.AnexampleofaregenerativeprocessistheuseofanaqueousaminesolutiontoremovetheH2SandCO2fromasourgasstream.Theaminesolutionisthenregeneratedbyreducingitspressureandheatingittoabout250°F.Thesolutionisthencooledandrecycledforreuse.Regen-erativetreatingprocessescanbebroadlyclassifiedasthosethatdependon:

• chemicalreactionin – amine-basedsolvents, – nonaminebasedsolvents;• physicalabsorption;• mixedchemical/physicalabsorption;• adsorptiononasolid.

CHEMICAL REACTION

Intheseprocesses,H2Sand/orCO2arechemicallyboundtotheactiveingredi-entinthetreatingsolution.Therefore,theresiduegascanbetreatedtoretainonlyverylowlevelsofthesecontaminants.Thechemicalsolventprocessesincurrentcommercialprocessesuseweakbaseslikealkanolamines,alkali saltsolutions,potassium carbonate,orachelate solution.

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5 Sulfur Recovery and Claus Off-Gas Treating

SULFUR RECOVERY

Gastreatingplantsmuststrictlycomplywithlegal,government,andsafetystandardsandregulationsconcerningemissionsandpollution.Duringthetreatmentprocess,H2SandsomeormostoftheCO2areremovedfromthesourgasstream,asdiscussedinChapter4.Theseremovedsourgascompo-nentsmustbedealtwithcautiously.

Whiletheemissionsrequirementsvarywithgeography,mostcountriesdonotpermittheemissionofmorethanafewpoundsofsulfur(H2S,SO2,etc.)perdayintotheatmosphere.Tocontrolemissions,theacidgasstreamfromatreatingplantisfedtoasulfurrecoveryunit(SRU)whereH2Sandothersulfurcompoundsareconvertedandrecoveredasnontoxicelementalsulfur(S).ThetailgasfromtheSRUstillcontainssomesulfurcomponents.TheseareconvertedtoSO2inanincineratorbeforebeingdischargedintotheatmosphere.Ifhigh(99.8+%)sulfurrecoveryisdesired,theSRUtailgasisfedtoatail-gastreatingplantforfurtherreductionofsulfuremissions.

Thermal ProcessIn1883,anEnglishscientist,CarlFriedrichClaus,discoveredandpatentedaprocessinwhichH2Swasreducedtoelementalsulfurandwaterinthepresenceofacatalyst.

Claus’sformulaforthisprocessis:

H2S+½O2 = S+H2O

Thecontrolofthisexothermic,orheat-releasing,processwasdifficult,andconversiontoelementalSwaslow.ThemodifiedClausprocessusedtodayovercomesthecontrolandconversionproblemsbydividingtheClausprocessintothefollowingtwosteps:

Thermal StepInthisexothermicstep,theair-to-acidgasratioiscontrolledsothataboutNoftheH2SisoxidizedtoSO2.Forgasescontaininghydrocarbonsand/orammoniafromasourwaterstripper,enoughairisinjectedtoensurecom-pletecombustionofammoniaandhydrocarboncomponents.Theprocesstemperatureduringthisstepisfrom1,800°F–2,500°F.

Catalytic StepIn thismoderately exothermic catalytic reaction, the sulfurdioxide (SO2)formedinthethermalsectionreactswithunburnedH2Stoformgaseouselementalsulfur.Thecatalystusedinthisstepismadefromactivatedalu-minaortitaniumdioxide.

Otherthanthereactionsofhydrocarbonsandothercombustibles,thekeyreactionstakingplaceare:

Thermal Reaction:

H2S+1½O2 = SO2+H2O

Thermal and Catalytic Reaction:

2H2S+SO2 = 3S+2H2O

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6 Dehydration and Mercury Removal

DEHYDRATION

Allhydrocarbonfluids can retain somewater.Water is soluble in liquidhydrocarbonsandcanbeheld in thevaporphasebyhydrocarbongases.Whenaliquidorgasiscooled,itscapacityforcontainingwaterdecreases.Asaresult,itcanproduceliquidand/orsolidwatercalledhydrates.Hydratesareaseparateandproblematicpartofgasprocessing.

Figure6.1showshowthewatercontentofnaturalgasvarieswithtem-peratureandpressure.Forexample,at1,000psiaand100oF,water-saturatednaturalgascontainsabout62poundsofwaterpermillionstandardcubicfeet(MMscf)ofgas.At1,000psiaand0oF,thegascontainsonlyabout2poundsofwaterperMMscfofgas.

Thewaterdewpointofagasorliquidisthetemperatureatwhichfreewaterwillbegintoseparatefromthegasorliquid.Ifanaturalgasstreamat1,000psiacontains62poundsofwaterperMMscfofgas,itswaterdewpointis100oF.Ifitiscooledbelow100oF,freewaterwillbepresent.

Hydrateswillformifagasorliquidcontainingfreewateriscooledbelowitshydratetemperature.Thegraphshowninfigure6.2canbeusedtoestimatethehydratetemperatureofnaturalgas.Forinstance,a0.6specificgravitygashasahydrate temperatureofabout61oFat1,000psia. If thisgasmustbecooledbelowitshydratetemperature,eitherduetopipelinetransportation,pressurereductionforconsumption,orforprocessing,pre-cautionsmustbetakentopreventfree-waterdropoutthatcausesfreezingandformationofhydrates.

Hydratesaresolidcompoundsthatformascrystalsandresemblesnow.Theyarecreatedbyareactionofnaturalgaswithwater,andwhenformed,areabout10%hydrocarbonand90%water.Hydrateshaveaspecificgravityofabout0.98andwillfloatinwaterandsinkinhydrocarbonliquids.Freez-ingcanbeavoidedbyeitherremovingthewaterfromthegasorliquidpriortocoolingbelowthehydratetemperatureorbyusingahydrateinhibitortomixwiththewatercondensedduringcooling.

Dehydrationistheprocessofremovingwaterfromasubstance.Dehy-drationcanbeaccomplishedbyusingsolidsubstancessuchasthoseusedindry-beddehydrators.Itcanalsobedoneusingaliquid,suchastriethyleneglycol.A stripping gasinaTEGreboilercanalsobeused.Themorecommonhydrateinhibitorsaremethanolandethyleneglycol.Mostnaturalgasfacili-tiesuseoneormoreofthefollowingdehydrationprocesses:ethyleneglycolinjection,TEGdehydration,ordry-beddehydrators.

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7 NGL Recovery—Lean-OilAbsorption

Straightfromthewell,naturalgasisamixofhydrocarbons,includingmeth-ane,ethane,propane,andbutane.Italsocontainsmanynonhydrocarbons,suchasnitrogen,helium,carbondioxide,hydrogensulfide,andwater.Rawgasisprocessedtoseparatethesecomponents.Theseprocessescontinuetoimprovewithadvancedtechnology.

Previously,whenkerosenewasahighlyvaluedproductandnaturalgaswassimplyanunwantedbyproduct,mostnaturalgaswaswasted.Gaswascommonlyflaredoff—aprocessthatoftencontinueddayandnight.Littlewasdonetocaptureanygasproducts.Afewoperatorsputtrapsintheirlinestocatchdrip gas.Aformofgasoline,dripgasnaturallycondensesasitcomesfromthenaturalgaswellsandcoolsinfield-gatheringlines.

Gasolinebegantosurpasskerosenesalesaround1912.Thefirstgasprocessorslearnedtoincreasetheyieldofdripgasbycompressingthegasandallowingittocool.Withthedemandforfuelgasolinegrowingquickly,producersbegantryingtogetmoreusableproductsfromtheoilandgas.Anincreased-yieldprocess,calledlean oil absorption,wasdevelopedinthe1920s.Leanoilisahydrocarbonliquid,usuallylighterthankerosene.Incontactwithnaturalgas,leanoilabsorbssomeoftheheavierhydrocarbonsfromthegas,whichcanbeseparatedfromtheoillater.Usingthisprocess,operatorsrecoveredmoregascondensateaswellasbutane,agasthatliquefieseasilyunderpressure.ThiswasthebeginningoftheNGLmarket.

Inthe1950s,processorsimprovedtheyieldfromlean-oilabsorptionbyaddingrefrigerationtotheprocess.Advancingtechnologyhasaddedthedevelopmentofbetterrefrigerationequipment,lowerprocessingtempera-tures,andnewwaystomarketnaturalgas.

Lean-oilabsorptionisonlyoneofmanywaystoseparatethevariousproductsinnaturalgas.Insteadofusinglean-oilabsorption,plantsmightusealessexpensiveprocessbyrefrigeratingthegastoremovethepropaneandheavierhydrocarbons.Manyofthenewestgasprocessingplantsonlyproducea singleNGLproduct calledY-grade,which is then shipped toanotherplantforfurtherseparation.

Chapter 7presents theolder, but still commonlyused, lean-oil ab-sorptionprocess.Chapter8coversthenewerprocessesofrefrigerationandturboexpansion.However,thecompleterangeofprocesspossibilitiescannotbefullyexploredinthesechaptersbecausegasplantsoftenusecombina-tionsandmodifiedversionsoftheseprocesses,dependingontherangeofproductsproduced.

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8 NGL Recovery-Cryogenic

Theheavierhydrocarbons,generallyreferredtoasNGLs,mightneedtoberemovedtocontrolthehydrocarbondewpointand/orthegasheatingvalue.However,heavierhydrocarbonscanalsobeasourceofincomeforthegasproducer.Thehistoryoftheevolutionofliquidsrecoveryfacilitiesfrom simple oil absorption to cryogenic expanderprocesses is complex(Elliot,1996).

Lean-oilabsorptionprocesses,suchastheambientandrefrigeratedprocesses,werecommonlyuseduntiltheearly1970s,asshowninfigure8.1.

Figure 8.1 Lean-oil absorption process and cryogenic process

The refrigeratedoil absorptionprocesswas introduced in 1957bymodifyingtheambientoilabsorptionprocesstooperateatlowertempera-tures.ThisallowedtheuseoflowermolecularweightoilswhichrecovermoreNGLsthanthehighermolecularweightoils,usedintheambientprocess.Atatemperatureof–40oF,therefrigeratedoilabsorptionprocesscouldbeusedtorecoverupto40+%ethaneand90+%propaneinthefeedgas.

Amajorshiftinthegasprocessingindustrybeganwhenthefirstlow-temperatureexpanderplantwasbuiltandbroughtintooperationin1964.Thebasicdesignofthisplantremainstoday.Duringthe1970s,theexpanderplantbecamethedominantprocessschemeusedtorecoverNGLsfromfeedgas.Itisanefficientprocessforhighethaneandpropanerecovery.

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9 Fractionation and LiquidTreating

FRACTIONATION

Thebasisformosthydrocarbonphaseseparationsistheequilibriumflashprocess.Aflashprocessgivesa“sloppy”or impreciseseparationof thecomponentsinamixture.Theliquidandvaporphasesoftheflashprocessstillcontainallthecomponentsthatwerepresentinthefeedgas.Tobetterseparate the feedcomponents,aprocesscalledfractionation,ordistilla-tion,wasdeveloped.Fractionationispossiblewhenthecomponentstobeseparatedhavedifferentboilingpoints.Thehigher thedifference in theboilingpoints,theeasieritistoseparatethecomponents.

Duringfractionation,amixtureisseparatedintoindividualcompo-nentsorgroupsofcomponents.Fractionationisacountercurrent operationinwhichvapormixtures are repeatedly brought in contactwith liquidmixtureshavingsimilarcompositionasthevapors.Theliquidsareattheirbubble pointsandthevaporsareattheirdewpoints.Bubblepointisthetem-peratureatwhichthefirstbubbleofgasformsinliquid.Partofthevaporcondenses,andpartoftheliquidvaporizesduringeachcontact.Thevaporbecomesricherinthelighterorlowerboilingcomponents,andtheliquidbecomesricherintheheavierorhigherboilingcomponents.

Afractionatingcolumncanbeviewedasacombinationofabsorptionandstrippingcolumns.Figure9.1isaschematicdiagramofafractionationcolumnwiththeassociatedandperipheralequipment.

Thecoolinginacondenserisdoneeitherbyair,coolingwater,orarefrigerantsuchaspropane.Thecolumnpressurenormallydeterminesthecoolingmediumthatisused.Reboilerheatisprovidedbysteam,hotoil,hotmediumfluids,hotcompressordischargegas,orahotprocessstream.

Thenumberoftraysortheheightofthepackedsectioninafraction-ationcolumndependsuponthenumberofvapor/liquidcontactsrequiredtomake the desired separation. Fractionation columns usevalve trayswithdowncomers orpipesthatmovethe liquidfromonetraytotheonebelow.Thevalvesopeneitherpartiallyorfullybyvaporflowingthroughthetray.Aweir maintainsliquidlevelonthetray.Liquidflowsacrossthetray,overtheweir,andthroughadowncomerordownpipetothetraybelow.Large-diametercolumnsmighthavetwoorfourliquidflow-passesoneachtray.Figure9.2showsflowthroughvaporpassagesonatrayinafractionationcolumn.

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10 Nitrogen Rejection Unit (NRU)

NITROGEN REJECTION

Nitrogen(N2)isaninertgasfoundinvaryingamountsinnaturalgasres-ervoirs.Nitrogen rejection is anecessaryprocess inmaintainingadesiredBtuvalueforsalesgasandpipelinespecifications.NitrogenisaddedtoorremovedfromthesalesgastoadjustitsheatingorBtuvalue.AddingnitrogenlowerstheBtuvalue,whileremovingnitrogenraisestheBtuvalue.How-ever,thereisalimittothemaximumamountofN2orinertgasesallowed.Nitrogenhasanadditionaluseintheenhanced oil recovery(EOR)processesandforincreasingoilproductionthroughreservoirinjection.

Nitrogenisremovedfromthefeedgasatlowtemperaturesinanitrogen rejection unit (NRU)designedaccordingto:

• Inletgascomposition• Inletgaspressure• Productspecifications• Ventnitrogen• Residuegasheatingvalue• Hydrocarbonrecoveryrequired

NRUsoperatebestunderstablecompositions,inletrates,temperatures,andpressures,andmustbedesignedtoefficientlyoperateoverabroadrangeofnitrogengascompositions(5%–80%).Thequantityofnitrogeninthefeedgasisgenerallythemainfactorinselectinganitrogenremovalprocess.

NRU PROCESS SELECTION

Thereare four categoriesofprocesses currently available for removalofnitrogenfromnaturalgas.

Pressure Swing Adsorption (PSA) Pressure swing adsorption isatechnologyusedtoseparatenitrogenunderpres-sureaccordingtoitsmolecularcharacteristicsandattractiontoanadsorbentmaterialatnear-ambienttemperatures.Specialadsorptivematerialsareusedasamolecularsieve,adsorbingthehydrocarboncomponentsathighpressure.Theprocessthenswingstolowpressuretodesorbtheadsorbentmaterial.Methaneisproducedduringthedesorptionstepatrelativelylowpressurenearambientorundervacuuminsomecases.Itoftenrequirespretreatmentandhashighcapitalandcompressioncosts.Therecoveryofmethaneisgenerallymoderate.

Cryogenic Absorption Thecryogenic absorption process useschilledhydrocarbonoiltoabsorbthebulkofthemethaneandachieveaseparationofnitrogenfromnaturalgas.Theabsorbedmethaneisstrippedofftheoilinaregeneratorandsubsequentlycompressedbacktothepipelinepressure.Theneedtoabsorbthebulkofmethanerequiresalargeoilcirculationflowandequipmentsize.Therefore,itismostsuitableforhighnitrogencontentstreams.Ithasnotbeenwidelyusedcommercially.

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Indexabsolutepressure,3absolutezero,2absorbers,98absorberworkings,99–100.absorption,36,51absorptionoil,99activatedcarbonprocess,62adiabaticexpansion(JT),148adsorbentlife,89adsorptiononasolid,61–62air-to-fuelratio,13alkalisaltsolutions,51alkanolamines,51,141amalgamation,92amalgamcorrosion,92ambienttemperature,58AmericanPetroleumInstitute(API),28AmericanSocietyforTestingandMaterials(ASTMInternational),109AmericanSocietyofMechanicalEngineers(ASME),28antiagglomerants(AAs),76APIgravity,3applications,gasprocessinggeneral,13–21applications,NGLrecovery-cryogenic ethane-recoveryprocess,121–122 propane-recoveryprocess,120 turboexpanderprocess,115–119aromatics,26associatedgas,1

biologicaloxidationprocess,57boilingpoint,6bottomstemperature,106Britishthermalunits(BTUs),10bubblecap,18bubble-pointline,116bubble-points,131butanesplittercolumn,137

carbondisulfide(CS2),53casestudy,95catalyticrecovery,68,70catalyticstep,67caustictreating,141centrifugalcompressors,32chelatesolution,51,57

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184 Plant Processing of Natural Gas

chemicalreactions amine-basedsolvents,52–53 biochemicalprocesses,57–58 diethanolamine(DEA),53 diglycolamine(DGA),53 formulatedamines,54 hinderedamines,54 hotpotassiumcarbonateprocess,57 methyldiethanolamine(MDEA),54 monoethanolamine(MEA),53 nonamine-basedprocesses,57–58 redoxprocess,57chillers,35,44chilling,148Claus,CarlFriedrich,67Clausoff-gastreating,70Clausprocess,54closedlooppropanerefrigerationsystem,38coalescentliquidlevelproblem,95coalescers,141cobalt(II)carbonylsulfide,53coldbox,152combustion,12–13comparisonofdew-pointprocesses,40composition,10compressors,1,32condensateproductstoragetanks,28condensatestabilizerreboilers,32condensatestabilizers,32condensers,16condensing,5contactorvessel,52contaminants,1controllers,44coolers,38coreexchangers,127corrosion,25,65corrosivity,53costestimate,35countercurrentoperation,131criticalpressures,3criticaltemperatures,3cryogenicabsorption,145cryogenicdistillation,146,148cryogenicNRUprocesses chilling,148 cryogenicdistillation,148 nitrogenrejectionunits(NRUs),146–148 pretreatment,147–148 recompression,148cryogenics,127–129

debutanizer,28debutanizer(DeC4)column,137deethanizer,120deethanizer(DeC2)column,137degradationproducts,53dehydration,4,73–80dehydrationandmercuryremoval,73–95dehydrationmethods designbasisandspecifications,92–93 designissues,88 liquiddesiccants,80,82–84 mercuryremovalunit(MRU),90 molecularsieveprocess,85–86 silicagelsandactivatedammonia,85 soliddesiccants,84–85deisobutanizer(DIB)column,137demethanizing,104depentanizer,28depropanizer(DeC3)column,137desiccants,147designbasisandspecificationsfordehydrationandmercuryremoval aboutgenerally,92 casestudy,95 designconsiderations,94–95 equipmentselectionanddesigns,95 gasdehydrationunits,92 generalconsiderations,92 technologyselection,92designbasisandspecificationsfortreatmentunits condensateproductstoragetanks,28 feedcasebasis,26 feedgas,26–28 productspecifications,27designcases,26designconsiderations designbasisandspecificationsfordehydration andmercuryremoval,94–95 free-liquidremoval,94 mercuryremovalcosts,94 MRUlocation,94 pressuredrop,94 superficialvelocityandresidencetime,95designissues adsorbentlife,89 dehydrationmethods,88 pooroutletwaterdewpoint,88–89 pressuredrop,89 switchingvalvesforadsorptionandregeneration operation,90desorption,37dew-pointcontrol,25

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Index 185

dew-pointcontrolandrefrigerationsystems,35–49 chillers,44 costestimateof,35 economizers,42 multiplestagerefrigeration,46 problems,44–46 processdescriptions,35–46 refrigerationsystems,41dew-pointdepression,35diethanolamine(DEA),52diethyleneglycol(DEG),37differentialpressureindicator(DPI),102diisopropanolamine(DIPA),60distillation,108downcomers,131downstreamprocessing,23dripgas,97driveassembly,45drygasloss,12drypointtemperature,109drystills,108

economizers,42elementalsulfur,57entrainedwatervapor,12equilibrium,5equipmentselectionanddesign condensatestabilizerreboilers,32 condensatestabilizers,32 feedgas,28 gasandliquidheaters,32–33 mercuryadsorber,95 mercuryremovalafter-filter,95 pigreceivers,28slugcatchers,30stabilizeroverheadcompressors,32ethane-recoveryprocess,121–122ethyleneglycol(EG),37,77eutecticfreezingpoint,77evaporation,41evaporators,35exchangers,127exothermicprocess,67expanders,35

Fahrenheitscale,2feedgasbasis,26feedgasreceivingandcondensatestabilization,23–33 designbasisandspecificationsfortreatment units,26–28

equipmentselectionanddesign,28 treatingandprocessing,23–26feedstock,1filtration,65firepoint,13flammability,13flashing,32flashpoint,13flashtank,77flooding,140flow-controlvalve,25flowdiagrams,14,16,18,19-20flowrate,28fluegas,12fluid,1fluidproperties,1–4 gravity,3 miscibility,3 pressure,3 solubility,4 temperature,2–3foaming,65fractionation,131–133fractionationandliquidtreating,131–143fractionation,131–133 monitoringoffractionalizationplants,139–140 NGLfractionationplants,134–136 NGLproducttreating,141–143 operatingproblems,140 packedcolumns,134 productspecification,138fractionationcolumn,26free-liquidremoval,94freezing,103freezingpoint,6Fuller’searth,143fundamentals combustion,13 composition,10 fluidproperties,1–4 heatenergy,10–12 hydrates,7–9 idealgaslaw,4–6

gallonsperminute(gpm),100gasandliquidheaters,32–33gascap,1gaschiller,41gasdehydrationunits,92gas/gasexchanger,38

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186 Plant Processing of Natural Gas

gaspermeation,62GasProcessorsSuppliersAssociation(GPSA),6gasproductionstreams,1gassub-cooledprocess(GSP),119gassurgetank,41gastreatment,1gastreatmentunit,26gaugepressure,3generalconsiderationsfordehydrationandmercuryremoval,92generaloperatingconsiderationsforgastreating,65glycol,4glycolcryogenicprocess,38glycolinjectionproblems,78–80glycol/J-Tvalvecoolingprocess,38–40glycol/propanesystem,37–38GPSA Engineering Data Book,28,84gravity,3grossheatingvalue,12

heatenergy,10–12heatingvalue,12heavy-liquidproduct,20high-integritypressureprotectionsystem(HIPPS),28high-liquidlevelalarm(HLA),102horsepower,10hot-richoilflashtank,104hydrateplug,7hydrates,7,8–9,73hydrocarbondew-pointcontrol,35hydrocarbonfluids,1hydrocarbontreating,51–65 adsorptiononasolid,61–62 chemicalreactions,51–58 gastreatingprocesses,51 generaloperatingconsiderationsforgastreating,65 membraneprocesses,62–64 mixedchemical/physicalabsorptionprocesses,60 physicalabsorptionprocesses,58–60hydrocarbontreatingunits,27hydrogensulfide,1

idealgaslaw aboutgenerally,4 boilingpoint,6 freezingpoint,6 liquidphase,5 vaporpressure,5–6immiscibleliquids,3incorrectcoalescerliquidlevel,95inhibitorinjection,76–80initialboilingpoint,13

inletseparation,65interstagecoolers,32

Joule-Thomson(J-T),35Joule-Thomson(J-T)expansion,117Joule-Thomson(J-T)valvesystem,38

Kelvinscale,2kinetichydrateinhibitors(KHIs),76KOdrum(knockoutdrum),36

latentheat,11leanglycol,77leanoil,44leanoilabsorption aboutgenerally,97 absorberworkings,99–100. potentialproblemswith,102–103 presaturation,100 recoverysystem,98–103levelcontrollers,44levelcontrolvalve,38liquiddesiccants,80,82–84liquidexpansion,6liquid-liquidtreating,141–142liquidphase,5liquidseparator,38liquid-solidtreating,143lowdosagehydrateinhibitor(LDHI),76lowtemperatureseparation(LTS),35

magneticbearings,126matter,10membraneprocesses,62–64membranes,146mercaptans,26mercuryadsorber,95mercuryembrittlement,92mercuryremovalafter-filter,95mercuryremovalcosts,94mercuryremovalunit(MRU),90Meroxprocess(commercialprocess),142metalsulfideoncarbonoralumina,93metalsulfidesystems,93methane,8methanol,7methyldiethanolamine(MDEA),52methylethyleneglycol(MEG),37millionstandardcubicfoot(MMscf),100miscibility,3

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Index 187

miscibleliquids,3mixedchemical/physicalabsorptionprocesses,60mole,10molecularpercent,10molecularsieve,35,93molecularsieveprocess,61,85–86molecularweight,10molecule,2monitoringoffractionalizationplants,139–140MRUlocation,94multiplestagerefrigeration,46mutuallysolubleliquids,4

naturalgas,1naturalgasliquid(NGL)fractionationplants,134-136 aboutgenerally,133–136 butanesplittercolumn,137 debutanizer(DeC4)column,136 deethanizer(DeC2)column,137 deisobutanizer(DIB)column,137 depropanizer(DeC3)column,137naturalgasliquid(NGL)producttreating,141–143 liquid-liquidtreating,141–142 liquid-solidtreating,143naturalgasliquid(NGL)recovery-cryogenic,113–129 aboutgenerally,113–114 applications,115–122 cryogenics,127–129 truboexpanders,122–126naturalgasliquid(NGL)recovery-leanoilabsorption,97–111 leanoilabsorption,98–103 rejectionsystem,104–107 separationsystem,108–111naturalgasliquid(NGL)recoveryoperations,77naturalgasliquids(NGLs),35“NaturalGasolineSpecificationsandTestMethods”(GPAPublication3132),138netheatingvalue,12nitrogenrejectionunits(NRUs) cryogenicNRUprocesses,146–148 NRUprocesses,149–152 processselection,145–146nonassociatedgas,1nonregenerativeacidgasremoval,51

off-gases,12oil-filmresonance,125oilpurification,109–110oil-to-gasratio,100oilwhip,125oilwhirl,125

operatingproblems,140.Seealsoproblemsoverheadproduct,134oxidation,57

packedcolumns,134paraffins,88physicalabsorptionprocesses propylenecarbonateprocess,59–60 Rectisol®process(commercialproduct),60 Selexol®(commercialproduct),59physicalpropertiescomparison,8–9pigging,30piggingfrequency,28pigreceivers,25,28pipelinegrid,35platefinexchangers,127pooroutletwaterdewpoint,88–89potassiumcarbonate,51poundspersquareinch(psi),3poundspersquareinchabsolute(psia),3poundspersquareinchgauge(psig),3prefractionator,150presaturation,100presaturationsystems,100pressure,3pressuredrop,89,94pressureindicators(PIs),44pressureswingadsorption,145pretreatment,147–148problems withdew-pointcontrolandrefrigerationsystems,44–46 withethane/butaneinpropane,44 withfractionators,140 inglycolinjectionsystems,78 withinadequateinletseparation,65 withleanoilabsorption,102–103 withmethanol,77 intherecoverysystem,102 withrejectionsystem,107 withretrogradecondensation,25 withseparationsystem,110–111 solvedbythegasfeedreceptionandcondensate stabilizationunitequipment,33 withsulfur-impregnatedcarbonsystems,92processdescriptions comparisonofdew-pointprocesses,40 dew-pointcontrolandrefrigerationsystems,35–46 glycol/J-Tvalvecoolingprocess,38–40 glycol/propanesystem,37–38 silicagelprocess,36–37 unitspecifications,40

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188 Plant Processing of Natural Gas

processengineers,2processselection cryogenicabsorption,145 cryogenicdistillation,146 membranes,146 nitrogenrejectionunits(NRUs),145–146 pressureswingadsorption,145productspecifications,27,138propane,3propane-recoveryprocess,120propylenecarbonateprocess,59–60

quenchcolumn,70

Rankinescale,2reboilers,16reciprocatingcompressors,32reclaimers,53recompression,148reconcentrators,38recoverysystems,98–103rectificationsection,21rectifying,21Rectisol®process(commercialproduct),58–60reflux,20,108refrigerationsystems,35,41regeneration,26regenerationgas,36regenerativeacidgasremoval,51regenerativemolecularsieve,93ReidVaporPressure(RVP)requirement,28,133rejectionsystem,98 hotrich-oilflashtank,104 possibleproblemswith,107 rich-oilflashdemethanizer,105–106retrogradecondensation,25richglycol,77richoil,99rich-oildemethanizer(ROD),105rich-oildemethanizerbottoms,105rich-oilflashdemethanizer,105–106rich-oilfractionator,107royaltycharges,59

safetyinstrumentalsystems(SIS),28SCOTprocess(commercialproduct),67,70Selexol(commercialproduct),59sensibleheat,11separationsystem,98

oilpurification,109–110 possibleproblemswith,110–111 still,108–109separationtower,18shell-and-tubeexchangers,16ShellClausOff-GasTreating(SCOT)process,67,70silicagelprocess,35,36–37silicagelsandactivatedalumina,85slipping(rejection),54slugcatchers,25,30soliddesiccants,84–85solubility,4“SpecificationandTestMethodsforLPGas”(GPAPublication2140),138specificgravity,3split-vaporprocess,119stabilizationcolumn,32stabilizeroverheadcompressors,32stackloss,12stagedseparation,42standardcubicfoot(scf),12stericallyhinderedamine-basedsolvents,54stills,107,108–109strippingsection,20subambienttemperature,58Sulfinol®process(commercialproduct),60sulfur-impregnatedactivatedcarbon,92–93sulfurrecovery,67–70 catalyticrecovery,68,70 catalyticstep,67 thermalandcatalyticreaction,67 thermalprocess,67 thermalreaction,67 thermalstep,67sulfurrecoveryandClausoff-gastreating Clausoff-gastreating,70 sulfurrecovery,67–70sulfurrecoveryunits(SRUs),54,67superficialvelocityandresidencetime,95sweeteningacidgases,51switchingvalvesforadsorptionandregenerationoperation,90

tailgas,54technologyselection designbasisandspecificationsfordehydration andmercuryremoval,92 metalsulfideoncarbonoralumina,93 regenerativemolecularsieve,93sulfur-impregnatedactivatedcarbon,92–93temperature,2–3

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Index 189

temperaturedifferential,12temperatureindicators(TIs),44thermalandcatalyticreaction,67thermalprocess,67thermalreaction,67thermalstep,67thermocouples,88thermodynamicinhibitors,76thiobacillusbacteria,57–58totalinstallationcost(TIC),93towers,67towerwithtrays,18trays,18treatingandprocessing,23–26triethyleneglycol(TEG),37triple-columncycle,149truboexpanders,122–126turboexpanderprocess,115–119turboexpansion,97

turndownratio,26Twister™Supersonicseparator(commercialproduct),40

unitspecifications,40upstream,25

vacuum,59valvetrays,131vaporization,53vaporizing,5vaporpressure,5–6vapors,4volatility,14volumeexpansion,6

waterdew-pointcontrol,35weirs,131wetstills,108workingfluid,35

Y-grade,97

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To obtain additional training materials, contact:

PETEXThe University of Texas at Austin

Petroleum extension service10100 Burnet Road, Bldg. 2

Austin, TX 78758

Telephone: 512-471-5940or 800-687-4132

FAX: 512-471-9410or 800-687-7839

E-mail: petex@www.utexas.eduor visit our Web site: www.utexas.edu/ce/petex

To obtain information about training courses, contact:

PETEXlearning and assessment center

The University of Texas4702 N. Sam Houston Parkway West, Suite 800

Houston, TX 77086

Telephone: 281-397-2440or 800-687-7052

FAX: 281-397-2441E-mail: plach@www.utexas.edu

or visit our Web site: www.utexas.edu/ce/petex

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Catalog No. 3.11020ISBN 0-88698-223-5

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Cover PageTitle PageTable of ContentsFiguresTablesForewordAcknowlegmentsAbout the AuthorsChapter 1: FundamentalsChapter 2: Feed Gas Receiving and Condensate StabilizationChapter 3: Dew-Point Control and Refrigeration SystemsChapter 4: Hydrocarbon TestingChapter 5: Sulfur Recovery and Claus Off-Gas TreatingChapter 6: Dehydration and Mercury RemovalChapter 7: NGL Recovery -- Lean-Oil AbsorptionChapter 8: NGL Recovery -- CryogenicChapter 9: Fractionation and Liquid TreatingChapter 10: Nitrogen Rejection Unit (NRU)AppendixGlossaryIndex