原油缓释.docx

原油缓释.docx

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原油缓释

Theoilcorrosioninhibitiontechnologyapplication

anddevelopmenttrend

ZhangQing

（TianjinOrientalWiseEnergySci-TechCo.,Ltd.Beijing2010）

Abstract:

Developmentofinhibitorwasoverviewedfromtheaspectsofinhibitinggroupandmolecularstructure.Theinhibitionmechanismsofelectrochemistryandphysicalchemistryweredemonstrated,andthefactorsaffectingtheinhibitioneffectwereanalyzedbymolecularstructuretheory.Finallytheapplicationanddevelopingdirectionsofinhibitorwerediscussed.

Keywords:

corrosionmechanism;inhibitor;inhibitinggroup;inhibitionmechanism;effectfactors

OilindustryinChina'snationaleconomyplaysaimportantposition.ThecorrosionofOilexplorationandprocessingprocessequipmentdirectlyaffecttheenterprise'ssafetyproductionandoperatingcycle.Theaccidentcausesbycorrosionofequipmentleadtoshutdowndevice,makingthepetrochemicalenterprisesufferedhugelossesineconomical.Equipmentanti-corrosionworkhasbecomeimportantintheproductionofoilprocessingwork.Thisarticleinviewoftheabovesituation,tooilextraction,transportationandprocessingequipmentanti-corrosiondorelatedresearch.

Sincemostoftheoilrecoveryliquidmoisturecontentmorethan90%,scalingtubingisserious.Togetherwiththewaterfailedtocomprehensivethestandard,infuseequipment,oilwellpipelineandgroundgatheringandtransportationpipelinehaveseriouslycorrosionphenomenon,evencauseperforationandscrap,seriouslyinfluencedoilfieldnormalproductionandlossenormouseconomic.Atpresent,theinjectioncorrosioninhibitormethodisacommonoilfieldantisepsismeasures.Butitexistthefollowingproblems:

a）.Thecorrosioninhibitorsfillingneedequipmentsuchasdosingpumpnotconvenient,largeworkload;b）.Corrosioninhibitorseasyadheretowalls,largeconsumption.c）.Theintermittentinfusedosinguneven,andeffectivelyprotecttimeisshort.Inaddition,somelargewaterproducewell,highwaterwell,remotewellandaddapackerofthewell,theusedofcorrosioninhibitorsalsoexistsomeinconvenience.

Oilpipelinecorrosionismainlycausedbythesedimentarywaterofcrudeoil,thecomprehensivemoisturecontentofcrudeoilriseto80%-90%inChina,thequalitycharacteristicsincreasinglycomplex,andsometimesevencontainhighconcentrationsofCO2,H2S,andcausepipelinecorrosionproblemsworse.Therefore,addefficientcorrosioninhibitorscanreducecorrosionandloss.Atpresent,corrosioninhibitortechnologyisdeveloptowardlow-toxicenvironmentalprotectionplanttypedirection.

Ⅰ,Thecorrosionmechanismofcrudeoilequipment

A.crudeoilimpurities

Crudeoilequipmentthemaincontactisoil,water,air,gas,acidgas,etc.Themainconstituentisallsortsofhydrocarbonalkyl,cycloparaffinandaromatics,theyarenotcorrodemetalequipment,butimpuritiescontainssuchasmineral,sulfide,nitrides,organicacids,oxygen,carbondioxideandwater,theselittlecontentofgreatharm.Becauseinthemachiningprocesssomeitselfiscorrosivemedium,andsomeotheralthoughitselfnocorrosivebutinthemachiningprocessbecomecorrosivemedium.Besidesduringtheoilextractionandprocessinginjectwater,hydrogenandacid-basechemicalsalsoformthecorrosivemedium,andthecorrosionmediumduringprocessinginthehigh-temperatureandhigh-pressureenvironmentwillhappenstrongcorrosionreactionsandwithmetalmaterials,thuscausingproductionequipmentcorrode.

B.sulfurcorrosion

Thesulphurofcrudeoilincludingtheelementalsulfur,hydrogensulphide,mercaptan,sulphuringether,vulcanization,chlorimiphenincompoundsandmolecularlargestructurecomplexsulfurcompounds.Generallydividethesulphurtoun-activesulphurandtheactivethatexistedincrudeoil.Theelementsulphur,hydrogensulfideandlowmolecularmercaptanetccandirectlyworkwiththemetalcauseequipmentcorrosioncalledactivesulphur;Therestwasun-activesulphur.Researchfoundthattheactivesulphurproducedcorrosionisrestrictbyenvironmentalfactors,especiallytheinfluenceofthetemperature.Insulfurcrudeoilprocessingprocess,becausetheun-activesulphurceaselesstransformtoactivesulphur,sosulfurcorrosionexistsnotonlyinoneprocessing,alsoexistinthesecondaryprocessingdevices,evenextendedtodownstreamchemicaldevice.Cansaythatsulfurcorrosionthroughoutthewholeprocessofrefining.Therehavemanyclassificationmethodofsulfurcorrosion,accordingtotheinfluenceoftemperatureonsulfurcorrosioncandivideditintotwotypes:

andlowtemperaturepartsofthecorrosioncorrosion.

Lowtemperaturepartscorrosion:

Usuallycalledthepartbelow120℃ofliquidwaterlowtemperaturearea.Thesepartsofthecorrosionalsocalledwethydrogensulfideorhydrogensulfidesolutionstatecorrosion.Withtheriseoftemperature,waterhasbeencompletelyvaporization,withoutliquidwaterconditionshydrogensulphideandhydrogenchloridedonotproducesignificantcorrosioneventhoughthetemperaturehighto240.therefore,torespondthehightemperaturepartssometimescallthebelowto240℃low-temperatureparts.

Hightemperaturepartsofthecorrosion:

mainlyreferstothecorrosionoccursinrefiningcontainsulfurorhighcrudeinoftenwhenthepressure-reliefdevicesmorethan240℃hightemperatureheavyoilplaceandcatalyticcracking,delayedcoking,thermalcrackingdevicesandcorrespondingpipelines,etc,partsofthecorrosion.

C.Environmentoftherefiningdevicecorrode

Thecorrosiveisenvironmentofoilextractionandprocessingismorecomplex,mainlydependsofthecrudeoilproperties,processingproducts,temperature,pressure,processingtechnology,equipmentpartsandotherfactors.Usuallycanclassitythecorrosiveenvironmentbyenvironmentaltemperatureandcorrosivemedium,andthisclassificationmethodsclassifieditintolow-temperaturecorrosiveenvironmentandhigh-temperature.Thelowtemperaturecorrosiveenvironmentinrefinery,usuallymeantemperaturebelowthe230℃andhaveliquidwaterexistedplace,whilethehigh-temperaturecorrosiveenvironmentmeansin240~500℃parts.

Ⅱ,Factorsaffectofoilcorrosion

Oilacidaretheaciditymaterialinoil,includingfattyacid,thenaphthenicacid,aromaticacidandothersubstancessuchasphenols,mercaptan,hydrogensulfide,inorganicacidetc.,accountofthemabout1-2%ofcrudeoil.Thenaphthenicacidinnormally90%orsocontentintheoilacid,whichisgeneralofakindcarboxylicacidmixtureofcomplexandwiderangeofboiling.Inthemetalsurfaceappearcharacteristicspitorinfluidflowregionhappenimpactcorrosionistypicalofnaphthenicacidcorrosion.Itwithamazingcorrosionratedamagethethealloymaterialusuallyusedinhibitsulfidecorrosion.Inmanycases,evenhighalloymaterials（suchas12Cr,austeniticstainlesssteel316and317）alsoappearedcorrosionphenomena.Maininfluencefactorsofnaphthenicacidcorrosionarethefollowing:

A.acidvalue

thetotalacidisanimportantparametersofThecrudeoiltomeasurevalueisthenaphthenicacidcorrosion.Thefirststudyconsiderthatthetotalacidvaluereachto0.5mgKOHofonegramoil,cancausethenaphthenicacidcorrosion.Numerousexperimentsshowthat,incertaintemperaturerangethenaphthenicacidcontentandtheacidvaluehavenodefiniterelationship,thatalsoexplaintherenodefiniterelationshipbetweencorrosionrateacidvalue.Becausetheprocessofoildistillation,acidcomponentscoexistwiththesameboilingpointoil,soonlytheacidvalueofdistillateoiltrulydecidedthenaphthenicacidcorrosionrate.

B.Sulfide

SisthemostcontentelementsinoilaftertheC,H.Itexistsintheformofelementalsulfur,hydrogensulphide,mercaptan,sulfide,polysulfide.TotalsulfurgenerallyusesASTMD4294methodtodeterminebytheX-rayfluorescencespectrometer,buttheheavymetalandhalidehavedistractions.

Asisknowntoall,sulfurcontentupto0.2%,willbecausethecarbonsteelandthelowalloysteelintherangeof230-455℃.Whensulfurcorrosionexistonlycanaccordingthecorrosioncorrosionfactorpredictionofcorrosion,thedistillateoilsulfurcontentandtheresultsofspecificanalysissulfidecanbetterpredictoilcorrosion,hydrogensulfideprecipitationexperimentalsocanpredictoilcorrosion.Inearly1953,havefoundthatthehydrogensulphideprecipitationcanwellcorrelatewiththecorrosionempiricaleguation,onlynowstandardmethoddon'tuseit[2].

Inhightemperatures,especiallyinthefurnacepipeandturnoilinlinenaphthenicacidcanacceleratesulfidecorrosion.Theseorganicacidcandestroysulfideprotectivefilmonthesurfaceofmetalandalloy,forexampleinlaterallinetubefractions,fornaphthenicaciddestroythemembraneformedbyhydrogensulfideeffect.

C.temperature

Generallyspeaking,allmetalcorrosionrateincreaseswiththeriseoftemperature,thenaphthenicacidcorrosionmainlyappearin220-400℃ofcrudedistillationregional.Lowerthan220℃thenaphthenicacidcontentisverylittleinoil,andhigherthan400℃therateofcarboxyloffofthenaphthenicacidingasphaseobviouslyimprove,maybethenaphthenicacidhappeneddecomposeorthecokeformedinmetalsurfacewasprotective[3~4].

D,Fluidvelocity

Fluidvelocityisthemainparametersaffectingthenaphthenicacidcorrosion.ForlacktheabilityofpredictcorrosionsouseshearstressthefluidassociatedandReynoldsnumberappearsmoreaccurate,becausetheycontainthedensity,viscosityandvaporizationdegreeandpipediameteroftheliquidandsteaminpipeline.Corrosionrateandwallshearstressisdirectlyproportional.Generally,thehigheracidvalue,th