EPA Method 15

918METHOD15-DETERMINATIONOFHYDROGENSULFIDE,CARBONYLSULFIDE,ANDCARBONDISULFIDEEMISSIONSFROMSTATIONARYSOURCESNOTE:Thismethodisnotinclusivewithrespecttospecifications(e.g.,equipmentandsupplies)andprocedures(e.g.,samplingandanalytical)essentialtoitsperformance.Somematerialisincorporatedbyreferencefromothermethodsinthispart.Therefore,toobtainreliableresults,personsusingthismethodshouldhaveathoroughknowledgeofgaschromatographytechniques.1.0ScopeandApplication.1.1Analytes.AnalyteCASNo.Sensitivity(SeeSec13.2)Carbondisulfide[CS2]75-15-00.5ppmvCarbonylsulfide[COS]463-58-10.5ppmvHydrogensulfide[H2S]7783-06-40.5ppmv1.2Applicability.1.2.1Thismethodappliestothedeterminationofemissionsofreducedsulfurcompoundsfromtailgascontrolunitsofsulfurrecoveryplants,H2Sinfuelgasforfuelgascombustiondevices,andwherespecifiedinotherapplicablesubpartsoftheregulations.1.2.2Themethoddescribedbelowusestheprincipleofgaschromatographic(GC)separationandflamephotometricdetection(FPD).Sincetherearemanysystemsorsetsof919operatingconditionsthatrepresentuseablemethodsfordeterminingsulfuremissions,allsystemswhichemploythisprinciple,butdifferonlyindetailsofequipmentandoperation,maybeusedasalternativemethods,providedthatthecalibrationprecisionandsample-linelosscriteriaaremet.1.3DataQualityObjectives.Adherencetotherequirementsofthismethodwillenhancethequalityofthedataobtainedfromairpollutantsamplingmethods.2.0SummaryofMethod.2.1Agassampleisextractedfromtheemissionsourceanddilutedwithcleandryair(ifnecessary).AnaliquotofthedilutedsampleisthenanalyzedforCS2,COS,andH2SbyGC/FPD.3.0Definitions.[Reserved]4.0Interferences.4.1MoistureCondensation.Moisturecondensationinthesampledeliverysystem,theanalyticalcolumn,ortheFPDburnerblockcancauselossesorinterferences.Thispotentialiseliminatedbyheatingtheprobe,filterbox,andconnections,andbymaintainingtheSO2scrubberinanicewaterbath.MoistureisremovedintheSO2scrubberandheatingthesamplebeyondthispointisnotnecessaryprovidedtheambienttemperatureisabove0EC(32EF)920Alternatively,moisturemaybeeliminatedbyheatingthesampleline,andbyconditioningthesamplewithdrydilutionairtoloweritsdewpointbelowtheoperatingtemperatureoftheGC/FPDanalyticalsystempriortoanalysis.4.2CarbonMonoxide(CO)andCarbonDioxide(CO2).COandCO2havesubstantialdesensitizingeffectsontheFPDevenafter9:1dilution.(AcceptablesystemsmustdemonstratethattheyhaveeliminatedthisinterferencebysomeproceduresuchaselutingCOandCO2beforeanyofthesulfurcompoundstobemeasured.)CompliancewiththisrequirementcanbedemonstratedbysubmittingchromatogramsofcalibrationgaseswithandwithoutCO2inthediluentgas.TheCO2levelshouldbeapproximately10percentforthecasewithCO2present.ThetwochromatogramsshouldshowagreementwithintheprecisionlimitsofSection13.3.4.3ElementalSulfur.Thecondensationofsulfurvaporinthesamplingsystemcanleadtoblockageoftheparticulatefilter.Thisproblemcanbeminimizedbyobservingthefilterforbuildupandchangingasneeded.4.4SulfurDioxide(SO2).SO2isnotaspecificinterferentbutmaybepresentinsuchlargeamountsthatitcannotbeeffectivelyseparatedfromtheothercompoundsofinterest.TheSO2scrubberdescribedinSection6.1.3willeffectivelyremoveSO2fromthesample.9214.5AlkaliMist.AlkalimistintheemissionsofsomecontroldevicesmaycausearapidincreaseintheSO2scrubberpH,resultinginlowsamplerecoveries.ReplacingtheSO2scrubbercontentsaftereachrunwillminimizethechancesofinterferenceinthesecases.5.0Safety.5.1Disclaimer.Thismethodmayinvolvehazardousmaterials,operations,andequipment.Thistestmethodmaynotaddressallofthesafetyproblemsassociatedwithitsuse.Itistheresponsibilityoftheuserofthistesttoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationstoperformingthistest.6.0EquipmentandSupplies.6.1SampleCollection.SeeFigure15-1.Thesamplingtraincomponentpartsarediscussedinthefollowingsections:6.1.1Probe.TheprobeshallbemadeofTeflonorTeflon-linedstainlesssteelandheatedtopreventmoisturecondensation.Itshallbedesignedtoallowcalibrationgastoentertheprobeatornearthesamplepointentry.Anyportionoftheprobethatcontactsthestackgasmustbeheatedtopreventmoisturecondensation.TheprobedescribedinSection6.1.1ofMethod16Ahavinganozzle922directedawayfromthegasstreamisrecommendedforsourceshavingparticulateormistemissions.WhereveryhighstacktemperaturesprohibittheuseofTeflonprobecomponents,glassorquartz-linedprobesmayserveassubstitutes.6.1.2ParticulateFilter.50-mmTeflonfilterholderanda1-to2-micronporosityTeflonfilter(availablethroughSavillexCorporation,5325Highway101,Minnetonka,Minnesota55343).Thefilterholdermustbemaintainedinahotboxatatemperatureofatleast120EC(248EF).6.1.3SO2Scrubber.Three300-mlTeflonsegmentimpingersconnectedinserieswithflexible,thick-walled,Teflontubing.(ImpingerpartsandtubingavailablethroughSavillex.)Thefirsttwoimpingerscontain100mlofcitratebuffer,andthethirdimpingerisinitiallydry.Thetipofthetubeinsertedintothesolutionshouldbeconstrictedtolessthan3-mm(c-in.)IDandshouldbeimmersedtoadepthofatleast50cm(2in.).Immersetheimpingersinanicewaterbathandmaintainnear0EC.Thescrubbersolutionwillnormallylastfora3-hourrunb