EPA Method 15A

943METHOD15A-DETERMINATIONOFTOTALREDUCEDSULFUREMISSIONSFROMSULFURRECOVERYPLANTSINPETROLEUMREFINERIESNOTE:Thismethoddoesnotincludeallofthespecifications(e.g.,equipmentandsupplies)andprocedures(e.g.,samplingandanalytical)essentialtoitsperformance.Somematerialisincorporatedbyreferencefromothermethodsinthispart.Therefore,toobtainreliableresults,personsusingthismethodshouldhaveathoroughknowledgeofatleastthefollowingadditionaltestmethods:Method1,Method6,Method15,andMethod16A.1.0ScopeandApplication.1.1Analytes.AnalyteCASNo.SensitivityReducedsulfurcompoundsNoneassignedNotdetermined1.2Applicability.Thismethodisapplicableforthedeterminationofemissionsofreducedsulfurcompoundsfromsulfurrecoveryplantswheretheemissionsareinareducingatmosphere,suchasinStretfordunits.1.3DataQualityObjectives.Adherencetotherequirementsofthismethodwillenhancethequalityofthedataobtainedfromairpollutantsamplingmethods.9442.0SummaryofMethod.2.1Anintegratedgassampleisextractedfromthestack,andcombustionairisaddedtotheoxygen(O2)-deficientgasataknownrate.Thereducedsulfurcompounds[includingcarbondisulfide(CS2),carbonylsulfide(COS),andhydrogensulfide(H2S)]arethermallyoxidizedtosulfurdioxide(SO2),whichisthencollectedinhydrogenperoxideassulfateionandanalyzedaccordingtotheMethod6barium-thorintitrationprocedure.3.0Definitions.[Reserved]4.0Interferences.4.1Reducedsulfurcompounds,otherthanCS2,COS,andH2S,thatarepresentintheemissionswillalsobeoxidizedtoSO2,causingapositivebiasrelativetoemissionstandardsthatlimitonlythethreecompoundslistedabove.Forexample,thiophenehasbeenidentifiedinemissionsfromaStretfordunitandproducedapositivebiasof30percentintheMethod15Aresult.However,thesebiasesmaynotaffecttheoutcomeofthetestatunitswhereemissionsarelowrelativetothestandard.4.2CalciumandaluminumhavebeenshowntointerfereintheMethod6titrationprocedure.Sincethesemetalshavebeenidentifiedinparticulatematteremissionsfrom945Stretfordunits,aTeflonfilterisrequiredtominimizethisinterference.4.3Dilutionofthehydrogenperoxide(H2O2)absorbingsolutioncanpotentiallyreducecollectionefficiency,causinganegativebias.Whenusedtosampleemissionscontaining7percentmoistureorless,themidgetimpingershavesufficientvolumetocontainthecondensatecollectedduringsampling.DilutionoftheH2O2doesnotaffectthecollectionofSO2.Athighermoisturecontents,thepotassiumcitrate-citricacidbuffersystemusedwithMethod16Ashouldbeusedtocollectthecondensate.5.0Safety.5.1Disclaimer.Thismethodmayinvolvehazardousmaterials,operations,andequipment.Thistestmethodmaynotaddressallofthesafetyproblemsassociatedwithitsuse.Itistheresponsibilityoftheuserofthistestmethodtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortoperformingthistestmethod.5.2Corrosivereagents.Thefollowingreagentsarehazardous.Personalprotectiveequipmentandsafeproceduresareusefulinpreventingchemicalsplashes.Ifcontactoccurs,immediatelyflushwithcopiousamountsofwaterforatleast15minutes.Removeclothingundershower946anddecontaminate.Treatresidualchemicalburnsasthermalburns.5.2.1HydrogenPeroxide(H2O2).Irritatingtoeyes,skin,nose,andlungs.5.2.2SodiumHydroxide(NaOH).Causesseveredamagetoeyesandskin.Inhalationcausesirritationtonose,throat,andlungs.Reactsexothermicallywithlimitedamountsofwater.5.2.3SulfuricAcid(H2SO4).Rapidlydestructivetobodytissue.Willcausethirddegreeburns.Eyedamagemayresultinblindness.Inhalationmaybefatalfromspasmofthelarynx,usuallywithin30minutes.Maycauselungtissuedamagewithedema.3mg/m3willcauselungdamageinuninitiated.1mg/m3for8hourswillcauselungdamageor,inhigherconcentrations,death.Provideventilationtolimitinhalation.Reactsviolentlywithmetalsandorganics.6.0EquipmentandSupplies.6.1SampleCollection.ThesamplingtrainusedinperformingthismethodisshowninFigure15A-1,andcomponentpartsarediscussedbelow.Modificationstothissamplingtrainareacceptableprovidedthatthesystemperformancecheckismet.9476.1.1Probe.6.4-mm(¼-in.)ODTeflontubingsequentiallywrappedwithheat-resistantfiberstrips,arubberizedheatingtape(withaplugatoneend),andheat-resistantadhesivetape.Aflexiblethermocoupleorsomeothersuitabletemperature-measuringdeviceshallbeplacedbetweentheTeflontubingandthefiberstripssothatthetemperaturecanbemonitored.Theprobeshouldbesheathedinstainlesssteeltoprovidein-stackrigidity.Aseriesofbored-outstainlesssteelfittingsplacedatthefrontofthesheathwillpreventfluegasfromenteringbetweentheprobeandsheath.ThesamplingprobeisdepictedinFigure15A-2.6.1.2ParticulateFilter.A50-mmTeflonfilterholderanda1-to2-mmporosityTeflonfilter(availablethroughSavillexCorporation,5325Highway101,Minnetonka,Minnesota55345).Thefilterholdermustbemaintainedinahotboxatatemperaturehighenoughtopreventcondensation.6.1.3CombustionAirDeliverySystem.AsshownintheschematicdiagraminFigure15A-3.Theratemetershouldbeselectedtomeasureanairflowrateof0.5liter/min(0.02ft3/min).6.1.4CombustionTube.Quartzglasstubingwithanexpandedcombustionchamber2.54cm(1in.)indiameterandatleast30.5cm(12in.)long.Thetubeendsshouldhave948anoutsidediameterof0.6cm(1/4in.)andbeatleast15.3cm(6in.)long.Thislengthisn