Dynamic Modeling and Simulation of Catalytic Hydrotreating

936Energy&Fuels2006,20,936-945

DynamicModelingandSimulationofCatalyticHydrotreating

Reactors

Fabia´nS.Mederos, MiguelA.Rodr ´guez, , JorgeAncheyta,*, ,§andEnriqueArce§

InstitutoMexicanodelPetro´leo,EjeCentralLa´zaroCa´rdenas152,Col.SanBartoloAtepehuacan,Me´xicoD.F.07730,FacultaddeIngenier ´a,UNAM,CiudadUniVersitaria,Me´xicoD.F.04510,andESIQIE-IPN,

UPALM,Me´xicoD.F.07738

ReceiVedDecember6,2005.ReVisedManuscriptReceiVedMarch9,2006

Thispaperdescribesadynamicheterogeneousone-dimensionalmodeloftrickle-bedreactorsusedforcatalytic

hydrotreatingofoilfractions.Themodelconsidersthemainreactionsinthehydrotreatingprocessofoilfractions:hydrodesulfurization,hydrodenitrogenation,andhydrodearomatization.ThedynamicmodelwasfirstvalidatedusingexperimentaldataobtainedinanisothermalpilotreactorduringhydrotreatingofvacuumgasoiloveracommercialNiMocatalyst.Then,themodelwasappliedtopredictthedynamicbehaviorofacommercialhydrotreatingreactor.Changesinconcentration,partialpressure,andtemperatureprofilesareobtainedanddiscussedasafunctionofreactoraxialpositionandtime.Thesimulationsobtainedwiththeproposeddynamicmodelshowedgoodagreementwithexperimentaldata.

1.Introduction

Catalytichydrotreating(HDT)isoneofthemostimportantprocessesinthepetroleum-refiningindustryfromtechnical,economic,andenvironmentalpointsofview.HDTprocesshasbeenusedforover60yearstoreducethepollutingcompoundcontent(sulfur,nitrogen,aromatics,etc.)infossilfuelsandtofulfilltheapplicablelegalnormsofgasemissions.Nevertheless,forthenextyears(inmid-2006),newregulationswillbeappliedworldwideandautomotivefuelswillhavetomeettheso-calledultralowsulfurspecifications(30ppmingasolineand15ppmindiesel).1Amongotherchanges(i.e.,newreactordesign,useofnewgenerationcatalysts,etc.),theseenvironmentalrestric-tionswillforcetherefineriestoincreasetheseverityintheoperatingconditionsoftheHDTplantstomatchthesemorestringentspecifications.2-4Withthesenewreactionseverityconditions,thebehaviorofHDTreactorswillbealtered;forinstance,lighthydrocarbonsmaybeproduced,H2consumptionwillincrease,theyieldofliquidfuelwillreduce,reactordelta-Twillalsoincrease,etc.Tofacethissituation,refinersrequireeitherdetailedexperimentaldataormathematicalmodelingtoolsthatallowthemtounderstandthephenomenaoccurringintheHDTreactor,withthemainpurposeofestablishingtheoptimaloperatingconditions.

Exceptfornaphthahydrodesulfurization(HDS),inwhichagas-solidfixed-bedreactorisused,reactorsemployedinallHDTapplicationsoperateintrickle-bedflow.Atrickle-bedreactor(TBR)consistsofacocurrentdownwardflowofgasandliquidoverafixedbedofcatalystparticles(poroussolids)

*Towhomcorrespondenceshouldbeaddressed.E-mail:jancheyt@imp.mx.

InstitutoMexicanodelPetro´leo. UNAM.

§ESIQIE-IPN.

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10.1021/ef050407vCCC:$33.50©2006AmericanChemicalSociety

PublishedonWeb04/13/2006

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