石油焦基本知识汇总Word文档格式.docx

石油焦基本知识汇总Word文档格式.docx

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Theresidueremainingwhenallofthecokeisburnedoff.Itismostlymetalsandsilica.

Calcineablecoke

Petroleumcokethatqualifiestobecalcined,i.e.,generallynonshotandlowinmetalsthatwillqualifyforanodegrade.Calcineablecokeisgenerallyreferredtoastheavailablesupplytocalciners.Alsoknownasgreencoke（seesame）.

Calcinedcoke

Petroleumcokeorgreencoke（seesame）thathasbeenprocessedinacalciner（seesame）

Calciner

Alargerotarykiln（similartoacementkiln）thatdrivesoffthemoistureandvolatilityofgreenorcalcineablecoke（seeeach）sothatthecokecanbeusedforaluminumanodes,ortitaniumdioxideapplications.Thekilnreceivesthecokeatthehigherendwherethecokeflowsdownhillasthekilnrotates.Atthesametimeheatedaircounterflowsuphillfromthelowerend,drivingoffthemoistureandvolatilematerial

Carbonrejection

Crudeoilcontainsawidevarietyofhydrocarbonmolecules,rangingfromasinglecarbonatom（methane）toverylongchainmolecules.Thelightermoleculesthatmakeupgasoline,jetanddieselcontainalowerratioofcarbontohydrogenthantheheaviermolecules.Inordertoconverttheheaviermoleculestolighterproducts,theheaviermoleculesmustnotonlybecracked,buttheexcesscarbonmustberemovedtoreducethecarbontohydrogenratioofthecrackedmaterial.

CirculatingFluidizedBed（CFB）Boiler

Atypeofboilerwherethesolidfuelisfluidizedinaverticalfurnace.Theadvantageforthepetcokeindustryisthat100%veryhighsulfurcokecanbeburned.Thesulfurisremovedbyadditionoflimestoneinthebedwhichformsaneasilyremovablecalciumsulfateash.

Coker

Arefineryprocessingunitthatconvertstheresidualoilfromthecrudeunitvacuumoratmosphericcolumnintogasoilthatcanbemadeintolightproducts（gasoline,jetanddiesel）,weak（i.e.,lowenergycontent）fuelgasandpetcoke.Thereare3types:

Delayed,Fluid,andFlexi（seeeach）.Theseareallbasicallycarbonrejectionschemes（seesame）.

Delayedcoker

Atypeofcokerwhoseprocessconsistsofheatingtheresidualoilfeedtoitsthermalcrackingtemperatureinamultiparallelpassfurnace.Thiscracksthelongchainheavycarbonandhydrogenmoleculesoftheresidualoilintocokergasoilandpetcoke.Bothareinaliquefiedforminthemixtureasitleavesthefurnaceandentersthecokedrum.

Inthedrum,thecokergasoilvaporizesandseparatesfromthemixture.Itisdirectedtoafractionationcolumnwhereitisseparatedintothedesirableboilingpointfractions.Theliquidcokesolidifiesinthedrumasitcoolsandthevelocityslowsdown.

Afterthedrumisfullofthesolidifiedcoke,thehotmixturefromthefurnaceisswitchedtoaseconddrum.Whiletheseconddrumisfilling,thefulldrumissteamedtofurtherreducehydrocarboncontentofthepetcoke,andthenwaterquenchedtocoolit.Thetopandbottomheadsofthefullcokedrumareremoved,andthesolidpetcokeisthencutfromthecokedrumwithahighpressurewaternozzle,whereitfallsintoapitforreclamationtostorage.

Largercokershaveseveralpairsoftandemdrums.

Demurrage

Contractsforrailcars,trucksandmarineshipsalwaysincludeaspecifiedtimelimitthattherespectivevehicleorshipwilltaketounloadorload.Thepenaltyfordelayingbeyondthetimeallowedisalsospecifiedineachcontract.Uponcompletionoftheactualloadorunload,thevehicleorshipownerpresentsthecustomerwithademurragebillspecifyingthetimedelaybeyondtheallowance,reasonsforitandthe$penalty.

Drymetricorshortton

Aunitofmeasureforbillingpetcokeweight,whichreferstothegrosscokeweightadjustedforexcludingthecontainedmoisturecontent.Togetthismeasure,thecokemustbetestedformoisturecontent（seesame）.Calcineablecoke（Seesame）isfrequentlymeasuredintheseunits.AlsoseeWetmetricton.

Energycontent

TheenergycontentofcoalandcokeisusuallyspecifiedineitherBTU/lborKcal/kg.Itismeasuredinacalorimeterthatliterallyignitesthetestsampleandmeasuresthetemperatureriseofthewaterbathsurroundingit.

Flexicoker

Theflexicokeraddsathirdvessel,agasifier,tothefluidcokertogasifythepurgecokeintoaweakfuelgas.Cokeismadein3areas:

purgecokefromtheheater,andbothlargerandsmallerrecoveredcokefinesfromtheweakgasscrubbers.Itisa“flexible”cokerinthatthegasifiercanberuntomakeeithermorecokeormoreweakfuelgas.

FluidCoker

Afluidcokerproducesmorelightproductyieldandlesscokebutthecokeishigherinmetalsandharderthanadelayedcoker.Theprocessisacontinuousfluidizedbedconsistingofareactorandaburnervessel.Feedissprayedontoseedpelletsofcokeinthereactorwhereitiscoked.Purgecokeisdrawnofftheburnervessel.

Fuelgradecoke

Petcokethatcompeteswithsteamcoalasfuelforafurnace,boilerorcementkiln.Ifthecokecontainslowmetals,itmayqualifyasanodegrade（seesame）.Thechoiceofwhetheracokermakesfuelgradevsanodegradeisdictatedsolelybythecrudeslateandthemetalscontenttherein.

Greencoke

Usuallyreferstocalcineablecoke,i.e,potentialanodequalitycokethatstillcontainsmoistureandvolatilematerial,i.e,beforecalcining.

HargroveGrindabilityIndex（HGI）

Ameasureoftherelativehardnessofthecokeintermsofresistancetogrinding.AnHGIbelow35usuallymeansaveryhardcokerequiringconsiderablegrindingbeforeitcanbeproperlysizedtomeetburnernozzlespecificationsforthepulverizedfeedtothefurnacewherethecokewillbeburned.AnHGIabove65isusuallyrecognizedasasoftcokethatwillgrindveryeasily.

LossonIgnition（LOI）

Cokethatisaddedtocoalinafurnaceoriginallydesignedforcoal,maynotfullyburninthefurnace.Somecokeparticlesescapetheflameenvelopeandarecaughtbytheprecipitatorsorbaghouses.ThisLOIresultsinreducedfurnaceefficiencyandsomecarboncontaminationofthefluegasashrecovered.

Metalscontent

Thedistillationprocessesoftheatmosphericandvacuumcolumnsresultinalmostallofthemetalscontentofthecrudetoconcentrateintheresidualoil（thecokerfeed）,andthenfurtherconcentratedinthecoker.Generallymetalsarenotaproblemtofuelgradecokebuyers,otherthanvanadiumtosome.Howeveranodegradecokebuyerspreferlowmetalsasthemetalstendtoreducetheefficiencyoftheanodeinthealuminumsmeltingprocess

Moisturecontent

Petcokeascutfromacokercontainsroughlyfrom7-10%moisturewhichthecokepickedupfromthesteamingandquenchoperations.Itismeasuredbyheatinga100gsampleofgroundcoke,untilthemoistureisgone,andthenreweighing.SeeWetmetrictonsandDryMetrictons.

NeedleCoke

Aspecialqualitycokeproducedfromaromaticfeedstocks.Ithasacrystallinestructurewithmoreunidirectionalpores.Itisusedforhighqualitygraphiteanodessuchasforelectricarcfurnacesinthesteelindustry.

Shotcoke

Duetomechanismsnotwellunderstood,thecokefromsomecrudesformsintosmall,tight,nonattachedclustersthatlooklikepellets,marblesorBB’s.Itusuallyisaveryhardcoke,i.e.,lowHGI（seesame）.Suchcokeislessdesirabletotheendusersbecauseofdifficultiesinhandlingandgrinding.Itisalsolessdesirableforcalcineablecokebecausetheshottendsto“pop”inthekilnreducingthethermalstability.

Spongecoke

Mostdelayedcokeisinaformthatresemblesasponge,i.e,sortofbubblylooking.

Sulfurcontent

Sulfurincrudenaturallydistributesitselfthroughouttherangeofthecrude’shydrocarbonmolecules.However,theresidualoilandcokeusuallyattractadisproportionatelyhigherSulfurpercent.Also,asmostlowsulfurcrudesbecomeextinct,refinerieswillrunhighersulfurcrudestherebyincreasingthecokesulfur.

VolatilityorVCM

Petcokefromacokercontainsasmallamount（<

10%）oflighthydrocarbonstrappedintheporesofthecoke.Theamountofsuchvolatilityisgenerallyrelatedtothehowhardthecokerfurnaceisdriven:

hotterfurnaceoutlettemperaturesresultinmorehydrocarbonsdrivenoffandthereforelowervolatility.

Wetmetricton

Fuelgradecokeistypicallysoldinthesebillingunitswhichisatastandard8%moisture.Ifthecoketestsforahigher%,thebillingweightisadjustedaccordingly.

2石油焦

石油焦（Petroleumcoke）是原油经蒸馏将轻重质油分离后，重质油再经热裂的过程，转化而成的产品，从外观上看，焦碳为形状不规则，大小不一的黑色块状（或顆粒），有金属光泽，焦碳的颗粒具多孔隙结构，主要的元素组成为碳，占有80wt%以上，其余的为氢、氧、氮、硫和金属元素。

石油焦具有其特有的物理、化学性质及机械性质，本身是发热部份的不挥发性碳，挥发物和矿物杂质（硫、金属化合物、水、灰等）這些指标決定焦炭的化学性质。

2.1石油焦分类及性质

石油焦的形态随制程、操作条件及进料性质的不同而有所差异。

从石油焦工场所生产的石油焦均称为生焦（greencokes），含一些未碳化的碳烃化合物的挥发份，生焦就可当做燃料级的石油焦，如果要做炼铝的阳极或炼钢用的电极，则需再经高温锻烧，使其完成碳化，降低挥发份至最少程度。

大部份石油焦工场所生产的焦外观为黑褐色多孔固体不规则块状，此种焦又称为海绵焦（spongecoke）。

第二种品质较佳的石油焦叫做针状焦（needlecoke）与海绵焦比，由于其具较低的电阻及热膨胀系数，因此更适合做电极。

有时另一种坚硬石油焦亦会产生，称之为球状焦（shotcoke）。

这种焦形如弹丸，表面积少，不易焦化，故用途不多。

石油焦具有其特有的物理、化学性质及机械性质，本身是发热部份的不挥发性碳，挥发物和矿物杂质（硫、金属化合物、水、灰等）这些指针决定焦炭的化学性质。

物理性质中孔隙度及密度，决定焦炭的反应能力和热物理性质。

机械性质有硬度、耐磨性、强度及其它机械特性，颗粒组成及其它加工和运输、堆放、贮存等性质影响的情形