Natural gas fuels the integration of refning and petrochemicals Risingoilpricesandweak fueldemandintherecent past have had a signifcant impact on gross refnery margin (GRM).Historicaldatashow thatrefnerieswithbottom-of-the-barrelprocessingfacilities andanintegratedpetrochemi-calscomplexhaveperformed welltostayaheadofthe competitionbecauseoftheir greaterfexibilitytomaintaina healthy GRM. A robust refnery confgurationthatisfexible enoughtoprocessavarietyof crudes,includingdiffcult opportunitycrudes,alongwith anintegratedpetrochemicals complexiskeytosustaininga healthy GRM. However,simpleintegration ofarefneryandapetrochemi-calscomplexmaynotbe enough.Integrationshouldbe smartenoughtoaddressvola-tilityinthemarketbyensuring a healthy GRM and minimising environmentalimpactby reducingcarbonfootprint.Use ofnaturalgasfueladdresses thisissuetosomeextentby enablingtherecoveryofvalua-blecomponentsfromrefnery off-gasesandfacilitatingthe releaseofagoodquantityof Maximising the use of natural gas in a refnery-petrochemicals complex offershigher margins and lower carbon emissionsTanMay TaRaphdaR, pRaveen yadav and M K e pRasadTechnip KT Indiawww.digitalrening.com/article/1000557 PTQ Q3 2012 1naphthaforthegenerationofa valuablepetrochemicalsfeed-stock.Italsoenablesthe productionofmoremiddle distillatefrombottom-of-the-barrelprocessingandhelps reducethecarbonfootprintof theoverallcomplex.Theprice differentialbetweencrudeand naturalgas,especiallyincoun-trieswherenaturalgasis readily available, makes the use of gas a hugely proftable prop-osition.Evenincountries wherebothnaturalgasand crudeareimported,thereisa caseforgasthatneedstobe looked into. This article aims to explorevariousoptionsavaila-bletorefnerstoenhancetheir GRMandreducetheircarbon footprintthroughtheuseof natural gas.Refnery fuel consumption and generationArefneryconsumesfuelgas andfueloilproducedfrom variousrefneryprocesses.No supplementaryfuelisrequired forrefneryoperation. Generally,naphthaisusedas feedandfuelforthehydrogen generationunitandgas turbines.Atypicalfuel consumptionpatternina Hydrogen plantUtilitiesProcess heatersFigure 1 Fuel consumption pattern in a refnery2 PTQ Q3 2012www.digitalrening.com/article/1000557Apetrochemicalscomplexis alsoamajorenergyconsumer. Asteamcrackerconsumeslot ofpowerinitscrackedgas compressorsandrefrigeration compressors.Typically,600-620 kWhofpowerisrequiredfor one ton of ethylene production. Generally,anaphthacrackeris anetexporteroffuelgasand fuel oil, while an ethane cracker is a net consumer of fuel gas. A paraxylenecomplexisanet consumeroffuelgas/fueloil andpower.About0.3tonsof fuelgasand320-360kWhof powerarerequiredforoneton ofparaxyleneproduction. Refneryproductssuchasfuel gas, fuel oil, naphtha and diesel areusedtosatisfythefueland powerrequirementofthe steamcrackerandaromatics complex.Naturalgascanbe utilised as fuel for an integrated refinery-cum-petrochemicals complexwhilemaintaining fexible product objectives. Use of natural gas in therefneryNaturalgasorregasifedliquid naturalgascanbeusedina refnery for various purposes:Fuelforprocessandutility heaters, replacing fuel oilFeedandfuelforthehydro-gengenerationunit,replacing naphthaFuelforgasturbines,replac-ing naphthaFuelforprocessheaters, replacing fuel gas.Eachofthesecaseswillbe discussed in detail.natural gas as fuel for processand utility heaters, replacingfuel oilUseofnaturalgasasafuelto replacefueloilprovidesthe opportunitytoeitherreduceor refnery is shown in Figure 1. Fired heaters in various proc-ess units consume about 40-50% offuel.Theutilitysystem, includingboilersandgas turbines,consumesabout30-40%offuelandthehydrogen generation unit consumes about 15-20%offuel.Thecontribu-tion of the hydrogen generation unitincludesbothfeedand fuel.Typically,arefnerywith secondaryprocessingfacilities suchasfuidcatalyticcracking (FCC)andhydrocracking consumesabout8-10wt%of crudethroughputasfuel, includingnaphthausedinthe hydrogengenerationunitand gasturbines.Iftherefneryis integratedwithapetrochemi-calscomplex,whichishighly energyconsuming,fuel consumptionissignifcantly higher. This fuel requirement is satisfed by fuel oil and fuel gas generatedfromvariousprocess units.Fueloilismainlygenerated fromthevacuumdistillation unitandtheFCCunitsmain fractionatorbottomsinthe absenceofbottom-of-the-barrel processing facilities in the refn-ery.Vacuumresidueis generallytakenthrougha visbreakerunittoproducefuel oil.Generationoffueloilcan varybetween5and50%of feedtothevacuumdistillation unit,dependinguponthetype ofcrudeprocessed,whilefuel oilfromtheFCCunitsmain fractionatorbottomscanvary between4and6wt%ofthe FCC units feed.Atypicalcontributionoffuel gasgenerationfromvarious process units of a refnery using ArabianHeavyandArabian Lightcrudemixisshownin Figure2.Delayedcoker,FCC unit,gasolineblock(catalytic reformingunitwithisomerisa-tionoralkylation),crude distillationunitandhydroc-racker/hydrotreaters(naphtha, kerosene,dieselandVGO) contributetypicallyabout40%, 16%,17%,2%and25%respec-tivelytowardsfuelgas generation from the refnery. Manymodernrefnerieshave anintegratedpetrochemicals complextoimproveproftabil-ity.Asignifcantamountof fuelgasisalsogeneratedfrom thenaphthacrackercomplex, whileasmallamountoffuel gasisgeneratedfromthe aromaticscomplex(excluding thecatalyticreformingunit). Typically,about16-17wt%of feedisconvertedintofuelgas intheethanecracker,while about17-18wt%offeedis convertedintofuelgasinthe naphtha cracker. Fuel oil gener-ation from the ethane cracker is negligible,butitcanbeashigh as 10 wt% of feed for the naph-tha cracker. MS block, 17%DCU, 40%FCCU, 16%CDU, 2%HCU & HDTs, 25%Figure 2 Fuel gas generation in a refnery2 PTQ Q3 2012www.digitalrening.com/article/1000557eliminatefueloilgeneration fromtherefnerybyutilising bottom-of-the-barrelprocessing technology.Sofar,thedelayed cokerunitisoneofthemost economicaloptionsforthis typeofprocessing.Othertech-nologiesthatareavailableand usedpresentlyofferlower yieldsofdistillatesanddonot eliminatefueloilgeneration completely.Newtechnology suchasslurryhydrocracking, whichisonthevergeof commercialisation,promisesto offerabetterdistillateyield andminimumresiduegenera-tion.However,ourdiscussion isrestrictedtothedelayed coker,sinceithasaproven operationaltrackrecord. Typically,adistillateyield (combining naphtha and diesel) ofabout65%isobtainedfrom thedelayedcoker,whichmay resultin10-12%moredistillate fromtherefnery.Additional naphthageneratedfromthe delayedcokercanbeusedas feedstockforthenaphtha cracker. Moreover, off-gas from thedelayedcokercontains goodamountsofethylene, ethane and propylene. Ethylene andpropylenecanberecov-ered and used as petrochemicals feedstockaftersuitabletreat-mentfortheremovalof impurities,whileethanecanbe senttoasteamcrackerforthe productionofpetrochemicals feedstocks.Thus,replacingfuel oilwithnaturalgasnotonly eliminateslow-valuefueloil generation,butalsoenhances refneryandpetrochemicals integrationalongwithhigh-valuemiddledistillate production.Thischangeover, replacing fuel oil by natural gas intheexistingfredheaters, requirescarefulevaluationof www.digitalrening.com/article/1000557 PTQ Q3 2012 3thethermal,mechanicaland hydraulicadequacyofexisting hardware,particularlywith respecttoburners,tubemetal-lurgy,refractory,airpreheater systems and so on. natural gas as feed and fuel for steam reformingHydrogenisoneofthemost importantutilitiesintherefn-ery.Itisrequiredtoremove impurities,includingsulphur andnitrogen,fromvarious refneryproductsandinterme-diatestreams.Hydrogenis producedmainlybythesteam reformingofnaphtha.The hydrogenrequirementvaries widely, depending on the crude processedandtherefnerys product specifcations.Typically,fourtonsofnaph-thaarerequiredasfeedand fueltoproduceonetonof hydrogen,whileabout3.5tons ofnaturalgasarerequiredto produceonetonofhydrogen. Useofnaturalgasasfeedand fuel for the hydrogen plant will releaseagoodquantityof naphtha.Thisnaphthacanbe utilisedfurtherforproducing value-addedpetrochemical feedstocks.Aswitchfrom naphthatonaturalgasrequires certain modifcations in various sections of the hydrogen gener-ation unit:Feedpumping/compression and preheating Naphtha pumps, naphthavaporisersandsuper-heatersarenotrequired,while anaturalgascompressormay be requiredhydrodesulphurisationIf regasifedliquidnaturalgasis usedasfeedstock,pre-desul-phurisationisnotrequireddue to the very low sulphur content ofthefeed.Additionally,natu-ralgasisolefnfree,sothere will be no threat from olefns to the reformer catalystReformerfringThestoichio-metricairrequirementwillbe changedduetothechangein thehydrogen-to-carbonratioof thefuel,whichwillcallfor burner tip modifcationshigh-temperatureshiftreac-tion,steamgenerationand pressureswingadsorptionA lowerloadonthehigh-temper-atureshiftreactorandlower steamgenerationduetoless fringaretobeexpected. Pressureswingadsorptionis generallynotaffectedbythis change-over.Replacing naphtha with natu-ralgasasfeedandfuelforthe hydrogenplantnotonlyhelps therefnerstoproducemore valuableproductsbutalso helps to reduce the carbon foot-printoftherefnery.Typically, thechangeoverfromnaphtha tonaturalgaswillhelprefners toreduceCO2emissionsfrom thehydrogengenerationunit by 25%.natural gas as fuel for gasturbinesThegasturbineisthemain workhorse for power generation intherefnery.Apartofthe powerrequirementoftherefn-ery is satisfed by steam turbines utilising the cogeneration poten-tialtogeneratevariouslevelsof steamrequiredintherefnery. Thebalancepartofthepower requirementissatisfedbygas turbines.Generally,naphthais usedasfuelforgasturbines. Typically,0.25tonsofnaphtha isrequiredtogenerate1MWh ofpowerfromagasturbine. Whennaphthaisreplacedby naturalgasasfuelforagas turbine,itreleasesasignifcant amountofnaphthawhichcan furtherbeutilisedforvaluable productgeneration.About0.2 tonsofnaturalgasarerequired for 1 MWh of power generation. This switchover also helps refn-erstoreduceCO2emissions from a gas turbine by 25-30%.natural gas as fuel for fred heaters, replacing fuel gasFuelgasismainlygenerated fromthefollowingrefnery sources:Saturatedgasfromthecrude distillation unit Off-gasesfromhydrodesul-phuri sati on/hydrotreati ng units:naphthahydrotreater, kerosenehydrotreater,diesel hydrotreaterandvacuumgas oil hydrotreater Off-gasfromthecatalytic reforming unit Off-gas from the FCC unit Off-gasfromthehydrocrack-ing unit Off-gasfromthedelayed coker unit Aromatics complexNaphtha cracker complex.Typicaloff-gasyieldsfrom variousrefneryunits,the aromaticscomplexandthe naphthacrackercomplexare showninFigure3.Totalfuel gasgenerationfromtherefn-eryaccountsforabout8-10 wt%ofcrudethroughput, whereasonintegrationwitha naphthacrackerandaromatics complexitcanbeashighas15 wt% of crude throughput. Table1showsthevaluable componentspresentinoff-gasesfromvariousrefnery processunits,anaromatics complexandasteamcracker complex.Arefnerythatisprocessing crudes with light ends typically hasasaturatedgasunitto recoverLPG.However,satu-ratedoff-gasfromthisunit, primarily consisting of methane andethane,stillcontainssome propane.Ethaneandpropane fromsaturatedgasunitoff-gas can be recovered in a cryogenic separationunitaftersuitable purifcationandcanbefedto thesteamcrackerforthe productionofethyleneand propylene. Hydrogenrecoveryfrom refneryoff-gasesisanimpor-tantfactorinreducingthesize ofanon-purposehydrogen generationunit.Thiscanbe achievedbydevelopinga hydrogenbalancemodelacross therefnery,identifyingthe constraints/fexibilityof 4 PTQ Q3 2012www.digitalrening.com/article/1000557Figure 3 Units producing refnery off-gasesCDUNHTCRUCrackerAromaticsHCUFCCUKHTDHTVDUDCUVGOHDTCrudeoil0-2Yield, wt% of feed 0.5 1 2 3 4-5 10-12 2-3 3-4 16-18 5Fuel gas poolhydrogenusage,andhydrogen pinchanalysisforpossible alternativesofhydrogenreuse fromoff-gases.Itshouldbe notedthatacarefultechno-economic evaluation is required beforeimplementingany projectforhydrogenrecovery fromoff-gases.Thereason behind is that, on the one hand, it reduces the size of the hydro-gengenerationunitandthus CO2emissions,while,onthe otherhand,itdegradesthe qualityofoff-gasesintermsof calorifcvalueandreducesthe opportunitytoburnhydrogen toreduceCO2emissions. However, for a larger hydrogen contributor,adedicatedrecov-erysystemisjustifed.A catalyticreformerisonesuch sourceforhydrogenrecovery. Techniphasdevelopedadedi-catedtoolcalledHyN.DTfor hydrogenmanagementtohelp refnersoptimisehydrogen recoveryandthesizeofon-purposehydrogengeneration units. Off-gasfromtheFCCunit anddelayedcokingunits containsagoodquantityof ethane,ethylene,propylene andsomepropane.Separate recoveryofethyleneand propylenethroughcryogenic separationaftersuitabletreat-mentmaybeeconomicalifthe quantityofgasissignifcant. Otherwise,acombinedrecov-erysectionwithacracker complexmaybeconsidered. Ethaneandpropaneseparated fromoff-gasesaresenttothe crackerforfurtherproduction of ethylene and propylene.Recoveryofvaluablecompo-nentssuchashydrogen, ethyleneandethanefromoff-gasessignifcantlyreducesthe availablefuelgasinthe www.digitalrening.com/article/1000557 PTQ Q3 20125productionofaromaticssuch asbenzene,tolueneandparax-ylene.Themiddlecutcanbe blendedinthegasolinepool. Recentspecifcationsofgaso-linelimitthearomaticscontent ingasoline,thusrestrictingthe blendingofreformateinthe gasolinepoolandleadingto theuseofalternateoctane boosterssuchasisomerateand alkylate. Octane booster isomer-ate is produced by isomerisation oftheC5naphthastream. However,ifweusetheC5 streamtoproducevaluable products(suchasethyleneand propylene)inasteamcracker, analkylationunitcanbe consideredforoctaneboosting. Isobutanereactswitholefns suchaspropyleneandiso-butylenetoproducealkylates inthepresenceofsolidor liquidcatalystinanalkylation unit.Generally,FCCC4 cutisa goodfeedstocktoproduce alkylates with a RON of 92 and above.Asignifcantquantityof ethyleneandpropylenecanbe recoveredfromFCCandcoker off-gases.Inaddition,ethane andpropanerecoveredfrom saturatedgasesfromthecrude refnery,leadingtoarequire-mentforanexternalfuelsuch asnaturalgas.Inotherwords, theuseofnaturalgasasfuel fortherefnerywillhelpto recovervaluablecomponents fromoff-gases,leadingto enhancedrefneryproftability. Achangeoverfromfuelgasto natural gas needs careful evalu-ationofexistinghardware, especiallyfredheaters,with respecttothermal,mechanical and hydraulic adequacy. synergies between refning and petrochemicals productionUseofnaturalgasasrefnery fuelunleashesahostofoppor-tunitiesintermsofsynergies betweenarefneryandpetro-chemicalscomplex.The availabilityoffull-rangenaph-tha(C5-165Ccut)asaresultof utilisingnaturalgasforsteam reformingandgasturbinescan befruitfullyusedasfeedstock forapetrochemicalscomplex. Fromthisfull-rangenaphtha,a portionofnaphtha(lightnaph-tha,mainlyC5)canbeutilised inasteamcrackerforthe productionofethyleneand propylene,whileC7-C9cut naphthacanbeutilisedforthe 4 PTQ Q3 2012www.digitalrening.com/article/1000557sourceyield, wt% of feedCDU0-2Depending on presence of light ends in crude, sourcefor ethaneCRU10-12Source for hydrogenFCCU3-4Source for ethane and ethyleneDCU4-5Source for ethane and ethyleneHCU2-3Used as fuel gas primarilyNHT0.5Used as fuel gas primarilyKHT1Used as fuel gas primarilyDHDT2Used as fuel gas primarilyVGO HDT3Used as fuel gas primarilyAromatics complex(excluding catalytic reforming)5Used as fuel gas primarilySteam cracker complex16-18Source for hydrogenRefnery off-gases with valuable componentsTable 1distillationunitandfromFCC andcokeroff-gasescanbe utilisedtoproduceethylene andpropylenebyprocessing inasteamcracker.Hence,the steamcrackercanbedesigned asadualfeedcracker(both liquidandgas)totakeadvan-tageofoff-gasesandany surplusnaphtha,leadingto more fexibility of operation. A Technip-designedsteam crackeriscapableoftaking anyfeed,fromethanetogas oil,providingagreatdealof fexibility.SpyrofromTechnip isfrstprinciple-basedsoft-warecapableofpredicting yield and run length accurately foranyfeed.Itisusedby ethyleneproducersworldwide tomonitorandcontrolcrack-ing furnace performance. A great deal of synergy exists betweentherefnery,aromatics complexandsteamcracker complex.Off-gasesfromthe FCCunitandcokercontaining ethyleneandpropylenecanbe integrated with the cold section ofthesteamcracker.Onthe otherhand,pyrolysisgasoline producedfromthesteam crackercontainsagoodquan-tityofxylenesandcanbe integratedwiththearomatics complex.Propyleneproduced from the steam cracker complex andbenzeneproducedfrom thearomaticscomplexare feedstocksfortheproduction ofcumeneandphenolfor producing bis-phenol and poly-carbonates.Figures4and5 showenhancedintegration between a refnery and a petro-chemicalscomplexwhen natural gas is used as fuel.Reducing carbon footprint: a bonusInadditiontoachievinggood synergy between a refnery and apetrochemicalscomplex,the useofnaturalgasasrefnery fuelhelpsinreducingthe carbon footprint of the refnery, especiallywhenfueloilis replacedbynaturalgas. Typically,thereplacementof fueloilwithnaturalgasgives abouta30%reductioninCO2 emissionsand*thereplace-mentoffuelgaswithnatural gasgivesabouta5-10%reduc-tioninCO2emissionsfrom fred heaters. This is in addition toareductionof25%inCO2 emissionsfromthehydrogen generationunitand25-30% fromgasturbines,whichcan beachievedbyreplacingnaph-tha with natural gas.Case studyThis study concerns a base case ofarefnerycomplexof15 milliont/ycapacitywitha steamcrackerandaromatics complex.Therefneryconsists of a CDU/VDU primary unit, a catalyticreformingunitand alkylationforgasolineproduc-tion,anFCCunitand once-through hydrocracker unit assecondaryunits,anda delayedcokerisconsideredfor bottom-of-the-barrelprocess-ing.Hydrotreatingofall productssuchaskerosene, diesel,naphthaandVGOis consideredtomeettheproduct 6 PTQ Q3 2012www.digitalrening.com/article/1000557Sat gas released from fuel gas poolFCC and coker off gases released from fuel gas poolMore ethylene productionMore propylene productionCracker

EthaneEthyleneandpropyleneEthylene and propyleneEthaneEnhanced ethylene production

Enhanced propylene production

Sat gas to purification and recovery section of cracker complexEthane Ethylene and propylene recovered as product

FCC and coker off gases to purification and recovery section of cracker complexEnhanced ethylene production

Enhanced propylene production

Light naphtha to steam crackingMore PX production More benzene production

C7-C9 cut naphtha to aromatics complexEnhanced gasoline production

Middle cut (C6-C7 cut) naphtha to MSNaphtha available when NG is used in steam reformer and GTFigure 4 Additional naphtha for petrochemicals productionFigure 5 Recovery of components from refnery off-gas for petrochemicals productionspecifcationsrequiredfor downstreamunitsandtomeet environmentalregulations. Sincelightnaphtha(mainlyC5 cut),whichisfedintothe naphthacracker,isnotavaila-bleforisomerisationfor boostingtheoctanenumberof gasoline,analkylationunitis consideredforthepurpose.C4 cutfromtheFCCunitisthe feedtothealkylationunit. Lightnaphtha(C5cut)froma naphthahydrotreaterand hydrocracker,alongwith hydrocrackerbottoms,isthe mainfeedtothenaphtha cracker.Pyrolysisgasoline generatedfromthenaphtha crackergoesthroughan aromaticsseparationunit,the aromatics are fed into a paraxy-lenecomplexandraffnateis recycledbacktothenaphtha cracker.Abutadieneextraction unitisconsideredwithinthe naphthacrackercomplex. Hydrogenisrecoveredfrom catalyticreformerandnaphtha crackeroff-gasesthroughpres-sureswingadsorption.The sulphurblockincludesan aminetreatingunit,sourwater stripper,amineregenerator unit and sulphur recovery unit. Ablockfowdiagramforthe base case refnery confguration isshowninFigure6.Alinear programmingmodelwas developed based on this confg-uration,withmaximisationof GRMastheobjectiveonthe following basis: Capacity:15milliont/y(300 000 b/d)Crude:50%ArabHeavyand 50% Arab LightDesiredproducts:ethylene, propylene,LPG,butadiene, gasoline,aviationturbinefuel, diesel, benzene and paraxyleneAbasecase(withoutsupple-mentaryfuelsuchasnatural gas)materialbalanceis performedusingthismodel andproductyieldsareshown inTable2underbasecase. Withthesameconfguration, the model was rerun with natu-ralgasasfuel,replacing off-gasesandnaphthaasfeed andfuelforhydrogengenera-tion and gas turbines.Integration between a refnery andapetrochemicalscomplex ismaximisedbyoptimisingthe refneryconfgurationtogener-atemorevalue-addedproducts suchasethylene,propylene, butadiene,benzeneandparaxy-lene.Therevised(naturalgas) casesmaterialbalanceis performedwithnaturalgasas therefneryfuel.Acomparison ofthematerialbalancesofthe 6 PTQ Q3 2012www.digitalrening.com/article/1000557 www.digitalrening.com/article/1000557 PTQ Q3 20127Note: lines are not connected where they cross.CDUNHTHGU GTSRUARUSWSATUPSAPSALPG treatKHTCCRUDHTALKVDUDCUVGOHDTCrudeoilHCUFCCULPG treatBlendingBlendingMix sepAromatic complexPRUNaphthacrackerH2H2SulphurFGLPGEthylenePropyleneButadieneGasolineATFDieselBenzeneP-XyleneCokeFigure 6 Base case refnery confgurationbase case and the revised case is shown in Table 2. Forthebasecase,apartof theheavyproductssuchas vacuumresidueandFCC bottomsisutilisedforthe generationoffueloiltosatisfy thefuelrequirementofthe complex.However,forthe naturalgascase,allheavy products are sent to the delayed coker,resultinginmore distillatesandamarginal increase in coke production.Fuelandlossareestimated basedonthetotalconsumption offuelgas,naphthausedfor hydrogengenerationandgas turbines,andfueloilconsump-tioninboilersandheatersfor thebasecase.Forthenatural gascase,estimatesarebased onnaturalgasandfuelgas consumption.Comparisonofthebasecase andnaturalgascasematerial balancesshowsthatabout7 wt%ofcrudeisconvertedinto valuableproductssuchas ethylene, propylene, LPG, buta-diene,gasoline,benzeneand paraxylenewhennaturalgasis usedasasupplementaryfuel intherefnery.Theincreasein productionofthesepetrochem-icalsfeedstocksisshownin Figure 8.8 PTQ Q3 2012www.digitalrening.com/article/1000557Feed/productBase case nG case KTawt%KTawt%Crude15 00010015 000100Ethylene4903.38055.4Propylene6504.37755.2Butadiene750.51000.7LPG7154.87304.9Gasoline205013.7230015.3ATF264017.6264517.6Diesel425028.3428528.6Benzene2351.63302.2Paraxylene4503.06454.3Coke10256.810507.0Sulphur3152.13152.1Fuel and loss210514.010206.8Natural gas0012258.2Comparison of base case and natural gas case material balancesTable 2CDUNHTHGU GTSRUARUSWSATUPSAPSALPG treatKHTCCRUDHTALKVDUDCUVGOHDTCrudeoilNGHCUFCCULPG treatBlendingBlendingMix sepAromatic complexPRUNaphthaand gas crackerH2H2SulphurFGLPGEthylenePropyleneButadieneGasolineATFDieselBenzeneP-XyleneCokeNote: lines are not connected where they cross.Figure 7 Natural gas case refnery confgurationFigure8showsthatthe increaseinproductionofethyl-ene,propylene,butadiene, benzene and paraxylene is 64%, 19%,33%,40%and43%, respectively,whichhasa signifcantimpactonGRM.In addition,thereisasignifcant reductioninCO2emissions, about2.5%,fortheentire complex.Thisreductioncanbe achieveddespitetheincreased productionofpetrochemicals feedstocks,whichconsumes additional energy.ConclusionUseofnaturalgasasrefnery fuelunleashesahostofoppor-tunitiestomakearefningand petrochemicalsbusinessmore effcient.Itbeneftsaninte-gratedcomplexinmultiple ways:Useofnaturalgasreleasesa goodquantityofnaphtha, whichisnormallyusedasfeed andfuelforsteamreforming andgasturbines.Thisnaphtha canfurtherbeutilisedfor producingvalue-addedpetro-chemicalsfeedstockssuchas ethylene,propyleneand paraxyleneUseofnaturalgasasfuelfor therefnerygivestheopportu-nitytorecovervaluable componentssuchashydrogen, ethane,ethyleneandpropylene from off-gasesReplacementoffueloilby naturalgasenablesarefnery toprocesscompletevacuum residueinthedelayedcokerto enhance distillate yield.Inadditiontothesepossibili-ties,whichhelptoimprove signifcantlytheGRM,theuse ofnaturalgasasfuelreduces thecarbonfootprintofarefn-erysubstantially.Theprice differential between natural gas andcrudeand,moreimpor-tantly,thepricedifferential betweennaturalgasandpetro-chemicalfeedstockssuchas ethylene,propylene,butadiene, benzene and paraxylene will be a key driver to consider natural gasasrefneryfuelforbetter integrationwithapetrochemi-cals complex.acknowledgementTheauthorsarethankfultothe managementofTPKTIfortheirkind permission to publish this article.SPYRO is a mark of Technip KT India.References1Taraphdar T, Reducing carbon footprint an integrated programme of process integrationtechniqueslowersCO2 emissionslevelsinrefneriesthrough energy savings, PTQ, Q2 2011, 65-73.2RatanS,vanUffelenR,Curtailing refneryCO2throughH2plant,PTQGas 2008.TanmayTaraphdarisGroupLeader, Refnery&Petrochemicals,inthe Process&TechnologyDepartmentof TechnipKTIndiaLtd.,NewDelhi.He holds a masters in chemical engineering from Indian Institute of Technology (IIT), Kanpur, India. Email: ttaraphdar@technip.compraveen yadavisaProcessEngineerin theRefning,ProcessandTechnology DivisionofTechnipKTIndiaLtd.He holdsadegreeinchemicalengineering fromIndianInstituteofTechnology, Kharagpur,andamastersinprocesses andpolymersfromIFPSchool,Paris, France. Email: pryadav@technip.comMKeprasadisHeadoftheProcess andTechnologyDepartmentofTechnip KTIndiaLtd.Hehasover30years experienceinprocessdesignandholds degreeinchemicalengineeringfrom OsmaniaUniversity,Hyderabad,India. Email: mkeprasad@technip.com8 PTQ Q3 2012www.digitalrening.com/article/1000557 www.digitalrening.com/article/1000557 PTQ Q3 20129Figure 7 Natural gas case refnery confgurationFigure 8 Percent incremental production of petrochemicals feedstocksLthylene64%l9%33%40%43%Propylene 8utadiene 8enzene ParaxyleneNG case8ase case

LinKsMore articles from the following categories: hydrogen Managementpetrochemicals