烟气脱硫外文文献--毕设使用

FINALTECHNICALREPORTSeptember1,2005,throughAugust31,2006ProjectTitle:ACOMPARATIVESTUDYOFSO2&SO3REMOVALINDRYINJECTIONFGDPROCESSESICCIProjectNumber:05-1/ER8PrincipalInvestigator:Dr.JavadAbbasian,IllinoisInstituteofTechnologyProjectManager:Dr.RonaldH.Carty,ICCIABSTRACTTheobjectiveofthisexploratoryresearchprojectwastogenerateexperimentaldataonthecomparativereactivitiesofdifferentcommerciallyavailableCa/Mg-basedsorbents(i.e.,limestoneanddolomite)towardSO2&SO3todeterminetheireffectivenessforremovalofSO3indryinjectionFGDprocessesdesignedforSO2removal.Toachievethisobjective,samplesofahighpuritydolomiteaswellasahighpuritylimestonewereprocuredfortestinginthisproject.Thesorbentswerecrushedandsieved,andthe-50/+40meshfraction(i.e.,dp=300-425µm)wasselectedfortestinginthisproject.Atotaloffiftyfour(54)sulfationtestsinvolvingdolomite/limestoneandSO2/SO3wereconductedinthethermogravimetricAnalyzer(TGA)reactor.TheresultsoftheTGAtestswithSO2indicatetherateofsulfationreactioninvolvingdolomiteandSO2isfirstorderwithrespecttoSO2concentrationandthatthereactivityofdolomitetowardSO2decreaseswithincreasingtemperatureabove650°C,whichmaybeattributedtopartialsinteringofthesorbentatelevatedtemperatures.TheresultsalsoindicatethattherateofsulfationreactioninvolvinglimestoneandSO2alsoappearstobefirstorderwithrespecttoSO2concentrationwiththereactivityincreasingwithincreasingtemperature.Howevertheapparentactivationenergyisverylow,suggestingthepossibilityofpartialsintering.Furthermore,theresultsindicatethatalthoughthereactivityofthedolomiteishigherthanthatofthelimestone,becauseofthehighercalciumcontentofthelimestone,thesulfurloadingofthelimestoneishigherthanthatofthedolomiteatallconditionstested.IntheTGAtestinvolvingSO3,(wheresulfuricacidwasusedastheprecursor),becauseofthehighdewpointofthesulfuricacidmixtureandtemperaturelimitationoftheinertPFA®feedline,condensationwasamajorexperimentalproblem.TheresultsindicatethatbecauseofthecondensationandthelowconcentrationofSO3usedintheexperiment,asignificantlevelofuncertaintyisassociatedwiththeactualconcentrationofSO3duringtheseruns.Therefore,itshouldbeconcludedthatthereactivitiesofthesorbentstowardSO3determinedinthisprojectaresignificantlylowerthanthe“actual”values.EXECUTIVESUMMARYDuringthepulverizedcoalcombustionprocesssulfurincoalisreleasedmainlyintheformofsulfurdioxide(SO2)inthefluegas.However,asmallfractionoftheSO2(i.e.,0.5%to1.5%)isfurtheroxidizedbytheexcessoxygeninthefluegastoformSO3thatcombineswiththemoistureinthefluegastoformamistofsulfuricacid,alsoknownasthe“blueplume,”whichisthebiggestimpedimenttoIllinoisbasincoalsdisplacingappalachiancoalsinnewlyscrubbedunitsinthesoutheast.Insomeinstances,utilitiesareexperiencingablueplumefollowingtheretrofitofselectivecatalyticreduction(SCR)forthecontrolofemissionsofnitrogenoxide(NOX)onunitsequippedwithFGD's.Inadditiontoenvironmentalproblemsandconcerns,sulfuricacidinthefluegascancausevariouspowerplantoperatingandmaintenanceproblems.Condensationofsulfuricacidhasasignificantdetrimentaleffectondownstreamequipment,includingfoulingandcorrosionofheattransfersurfacesintheairheater.Condensationofsulfuricacidinthefluegascanbecontrolledbyraisingthefluegastemperature.However,higherairheatertemperaturewillresultinloweroverallplantefficiency.InpowerplantsthatareequippedwithSelectiveCatalyticReduction(SCR)systemsforNOXcontrol,sulfuricacidcancausecatalystdeactivation.Finally,sulfuricacidreactswithammonia(injectedforNOXcontrolinSCR)toformammoniumsulfateandammoniumbisulfate.Thelatterisastickysolidsubstancethatcancombinewith,andcontaminateflyash,andfoultheairheater.SulfuricacidinthestackgasalsocontributessignificantlytoPM2.5releases,whichisexpectedtoberegulatedbyyear2010.Unfortunately,despitealltheproblemsassociatedwiththepresenceofSO3inthefluegas,thisareaofresearchhasnotreceivedmuchattention.Theresultsofpreviousstudiessuggestthat,dependingonthepropertiesandamountofsorbentusedandinjectionlocation20%-90%ofSO3canberemovedfromthefluegasbycalcium-basedsorbents.However,asystematicstudyofthecomparativereactivitiesofdifferentcommerciallyavailableCa/Mg-basedsorbents(i.e.,limestoneanddolomite)towardSO2&SO3isneededtodeterminetheireffectivenessforremovalofSO3indryinjectionFGDprocessesdesignedforSO2removal.Thegoalofthisprogramistogeneratethenecessaryinformationtoaidtheutilitiesintheselectionofsuitablealkalinesorbentsaswellassorbentsinjectionstrategiesfortheremovalofsulfuricacidfromthefluegasofcoal-firedutilityboilers.TheobjectiveofthisexploratoryresearchprojectwastogenerateexperimentaldataonthecomparativereactivitiesofdifferentcommerciallyavailableCa/Mg-basedsorbents(i.e.,limestoneanddolomite)towardSO2&SO3todeterminetheireffectivenessforremovalofSO3indryinjectionFGDprocessesdesignedforSO2removal.Toachievethisobjective,samplesofahighpuritydolomiteaswellasahighpuritylimestonewereprocuredfortestinginthisproject.ThedolomitesamplewasobtainedfromThorntonQuarrylocatedinIllinois,whilethelimestonesamplewasobtainedfromSouthernIllinoisPowerCooperativeInc.,(SIPC).Thesorbentswerecrushed,sieved,anddivid