Teknologi Pemrosesan Gas(TKK564)

Instructor:Dr.Istadi(http://tekim.undip.ac.id/staf/istadi )

il i di di idEmail:istadi@undip.ac.id

I t t B k dInstructorsBackground

BEng.(1995):Universitas DiponegoroMeng.(2000):Institut Teknologi BandungPhD.(2006):Universiti Teknologi Malaysia

Specialization:CatalystDesignforEnergyConversionP D i f E C iProcessDesignforEnergyConversionCombustionEngineeringComputationalFluidDynamic(CFD)ComputationalFluidDynamic(CFD)

CourseSyllabus:(Part1)CourseSyllabus:(Part1)y ( )y ( )1. DefinitionsofNaturalGas,GasReservoir,Gas

Drilling,andGasproduction(Pengertian gasalam,g p g ggasreservoir,gasdrilling,dan produksi gas)

2. OverviewofGasPlantProcessing(OverviewSistemPemrosesan Gas)Pemrosesan Gas)

3. GasFieldOperationsandInletReceiving(Operasi Lapangan Gasdan Penerimaan Inlet)

4. GasCompressionSystem (Sistem Kompresi Gas)5. GasTreating(Pengolahan Gas)

( )6. GasDehydration(DehidrasiGas)7. FirstAssignment8 Ujian TengahSemester8. Ujian TengahSemester

FIELDOPERATIONS:WellheadOperations

WellheadGasliquidseparatorInstrumentshedCondensateTankIfthegasisnonassociated,hydrocarbonliquidsknockedoutintheseparatormayberemixedintheseparatormayberemixedwiththegasorstoredinatankandremovedbytruck

FIELD OPERATIONS: PipingFIELDOPERATIONS:PipingOffshoreProduction:

M ll i db k l fManywellsaretiedbacktoplatformGasfrommultipleplatformsaretiedtogetherintolargepipelinethatgotothegasplant(usuallyonshore)

O h P d tiOnshoreProduction:FormanextensivenetworkofsmalllinesfromindividualwellsTieintoincreasinglylargerlinesTieintoincreasinglylargerlinesThesmallergatheringlinesmaybeabovegroundorburiedLargerlinesarealwaysburiedAb dli h i t i t i b t AbovegroundlinesaremucheasiertomaintainbutareexposedtotheatmosphereSurfacecoatingforcorrosionpreventionandpossiblyinsulationmayberequiredinsulationmayberequired

FIELDOPERATIONS:CompressionSt tiStations

Onshorecompressionstation boosterstationOnshorecompressionstation boosterstationBoosterstationsarerarelyusedinoffshoreproduction

inletsuctionseparators(scrubbers)toremoved d l dcondensedliquids

Dehydrationfacilities toreducecorrosionandmitigatehydrateformationmitigatehydrateformation.Whenrequired,chemicalinhibitorsforcorrosionandgashydratepreventionareinjectedintotheandgashydratepreventionareinjectedintothedischargedgas;meteringpumpsareusedtocontrolinjectionrates

Howtohandlecondensedliquidsatboosterstationsisaneconomic

decision ?decision?Liquidscollectionrequirestankage andtruckingtomovetheliquidstotheplant.q pThebenefitsarehigherlinecapacity,reducedcorrosionrates,andreducedchemicalhydrateandcorrosioninhibitorinjectionrates inhibitorinjectionrates.Piggingrequirementsarereduced,aswellasthepotentialforlargeliquidslugsenteringtheplant.P i li id b ki h i li li i h dPuttingliquidsbackintothepipelineeliminatestheneedfortanksandtruckingbutincreaseschemicalcosts,putsmoreimportanceongoodpigging,andprobablyincreases

lpipelinemaintenancecosts.

CompressorpowerrequirementsdependupongasflowandpressureratioBoosterstationhorsepowerrangesfromtheteenstothethousands.Compressorsaredrivenbyelectricmotors,internalcombustion

i d t bi engines,andgasturbines.Horsepowerrequirementsandavailabilityoffueldictatethebestchoice.Somecompressordriversareinternal combustionenginesthatSomecompressordriversareinternalcombustionenginesthathavebeeninservicefor50ormoreyearsandhavebeenrebuiltmanytimes.Compressorenginesareusuallyfueledwithnaturalgas.ThebestCompressorenginesareusuallyfueledwithnaturalgas.Thebestfuelissalesgasfromtheplantbecauseitiscleanandhasaconstantheatingvalue.However,thistypeoffuelingrequiresrunningpipebetweenthel db iplantandboosterstations.

FIELDOPERATIONS:PiggingO O S: gg gPigging istheprocessofforcingasolidobjectthroughapipeline.apipeline.Theprocessinvolvesinsertingthepig,viaapiglauncher,intothepipelinesandremovingitbyuseofapigreceiver.Pi i i d f f h f ll i f iPiggingisusedtoperformanyofthefollowingfunctions:

Provideabarrier betweenliquidproductsthatusethesamepipelineCheckwallthicknessandfinddamagedsectionsoflinesRemovedebrissuchasdirtandwaxfromlinesProvideaknownvolumeforcalibratingflowmetersProvideaknownvolumeforcalibratingflowmetersCoatinnerpipewallswithinhibitorsRemovecondensedhydrocarbonliquids andwaterintwophasepipelinesphasepipelines

Fieldoperationsmustfollowarigorouspiggingg gg gscheduletopreventtheplantfrombeinghitbylargeslugsofliquidthatwouldfloodinletreceivingandcarryliquidsintothegas processingunits carryliquidsintothegasprocessingunits.Fortunately,plantoperatorsusuallyknowwhenakillerpigiscoming,andtheydrawdownliquidkillerpig iscoming,andtheydrawdownliquidlevelsininletreceiving.Toprotecttheplantfromlargeliquidsurges,operatorsrespondbyshuttingingas,whichshutsdownfieldcompressorsandupsetstheplantwiththepotentialforproducingoff specproductsforproducingoffspecproducts.

Shapes of foam sphere and pigsShapesoffoamsphereandpigs

Foamspheres,likethoseshownintheleftfrontofFi l di th i li Figure3.5,aremorecommonlyusedingatheringlinesbecausemultiplespherescanbeloadedintoapiglauncherforremotelaunching.gThelauncherstypicallyholdthreetofivespheresandareinclinedsothatspherescanbeinsertedremotelybygravityfeedSpheresfornominal2to4inch(50to100mm)di t li lid h l diameterlinesaresolid,whereaslargeronesareinflated,usuallywithwaterorethyleneglycolwatermixtures.

Sphere launcher unitSpherelauncherunit

Attheendoftherun,thesphereiscaughtinasphereh ( ll ll d h f hcatcher(usuallycalledapigcatcherevenifspheresare

used).BothlaunchersandreceiversareonthestraightrunBothlaunchersandreceiversareonthestraightrunofapipetee.Pressuredifferentialdrivesthespherethroughtheli line.However,itusuallystopsintermittentlywhenitcomestolowpointswherepoolsofliquidaccumulatetolowpointswherepoolsofliquidaccumulate.Fieldandplantoperatorslearnthetypicalruntimesforspheresinaline,andinlinedetectorssignalah l isphereslocation.

GASHYDRATESPipelineblockageisusuallycausedby:

Waxandasphaltene solidsdeposition(lack)Waxandasphaltene solidsdeposition(lack)Scale(inorganicsalt)depositionGashydratesolidsformationy

First,hydrateplugscanoccurwithinminuteswithoutpriorwarning,whiletheothersolidstakeweeks,months oryearstocausepluggingandareusuallymonths,oryearstocausepluggingandareusuallydetectedbyincreasedlinepressuredrop.Second,althoughhydrateformationcanbeinhibitedg yinanumberofways,injectionpumpfailure,separatorfailure,andprocessupsetscansuddenlymakepipelinecontentsvulnerabletohydrateformation.contentsvulnerabletohydrateformation.

PropertiesofGasHydratesp y

Gashydratesareaclassofsolid nonstoichiometricGashydratesareaclassofsolid,nonstoichiometriccompoundscalledclathrates.Theyformwhenahostmaterial,waterforhydratesy , ythroughhydrogenbonding,formsacagedstructurethatcontainsguestmolecules,suchas

th methane.Bothhostandguestmustbepresentforthesolidtoform butnotallofthecageswillbeoccupied form,butnotallofthecageswillbeoccupied.Gashydratesshouldnotbeconfusedwithsalthydrates,whichformstoichiometric compounds.y , p

HYDRATE FORMATION PREDICTIONHYDRATEFORMATIONPREDICTIONThermodynamicsprovidesapowerfultoolforpredictionofthetemperatureandpressureforhydrateformationonthebasisofgascomposition.H d f i ki i i l d l Hydrateformationkineticsiscomplexandpoorlyunderstood,partlybecausethecrystalgrowthprocessisrandomisrandom

Forbelow1 000psi(70bar)Forbelow1,000psi(70bar),

ThespecificgravityisdefinedastheratioofthemassThespecificgravityisdefinedastheratioofthemassofagivenvolumeofagastothatofanequalvolumeofair;bothvolumesaremeasuredat14.7psia and60F( b d C) (1.01barand15.6C).Foranidealgas,thespecificgravityismolarmassofthegasdividedbythemolarmassofair(28 96)thegasdividedbythemolarmassofair(28.96).

ExampleGascomposition:

Estimatethehydrateformationtemperatureat325psia (22.4bar)fortheabovegascomposition?

Thespecificgravity=molarmassgas/molarmassair=20 08/28 96=0 69320.08/28.96=0.693.

t=16.56.83/(0.693)2+13.8 ln(325)=49F.

HYDRATE INHIBITIONHYDRATEINHIBITIONThreewaysexisttoavoidhydrateformationinnaturalgasy y gstreams:

Operateoutsidethehydrateformationregion.(impractical)( p )Dehydratethegas.Addhydrateinhibitor(themostcommonlyused)

Regardingdehydration howdryagasshouldbetopreventRegardingdehydration,howdryagasshouldbetopreventhydrateformationisuncertain.Thegasobviouslyshouldhaveawaterdewpointbelowthel i id d i lowestoperatingtemperaturetoavoidwatercondensation.Thermodynamicspredictsthathydratescanformevenwhenthegasphaseisunsaturatedwithwater.g p

Useofchemicalinhibitorsistheleastattractiveh d i hibi i h df lhydrateinhibitionmethodforseveralreasons:

Theproperinhibitordosagemustbeknowntoavoidpluggingorneedlesschemicalcosts,butoftentimesitisdeterminedempirically.Thechemicalcost,althoughitisusuallyasmallfractionofoveralloperatingcosts.Thereliabilityofinhibitorinjectioncanbeaproblembecauseofmalfunctioninginjectionpumpsanddepletedinhibitorreservoirs,especiallyatremotesites.Thepossibleinteractionbetweenhydrateinhibitorsandotheradditivesreducestheeffectivenessofsomeofadditives,aneffectthatisusuallydeterminedempirically.

ChemicalhydrateinhibitorsTypesy ypAntiagglomerates (AA) 1990sKi ti (KHI)Kinetic(KHI) 1990sThermodynamic

AntiagglomeratesAntiagglomeratesAntiagglomerates preventsmallhydrateparticlest agg o e ates p eve t s a yd ate pa t c esfromagglomeratingintolargersizestoproduceaplug.Theinhibitorsresideintheliquidhydrocarbonphaseandaremostoftenusedinpipelineswheregasisdissolvedinoil dissolvedinoil.Theyrequiretestingtoensureproperconcentrations.

KineticInhibitorset c b to s

Kineticinhibitorsslowcrystalfor