Coal Fired Flue Gas Mercury Emission Controls PDF
Preview Coal Fired Flue Gas Mercury Emission Controls
Energy and Environment Research in China Jiang Wu · Yan Cao Weiguo Pan · Weiping Pan Coal Fired Flue Gas Mercury Emission Controls Energy and Environment Research in China Moreinformationaboutthisseriesathttp://www.springer.com/series/11888 Jiang Wu • Yan Cao (cid:129) Weiguo Pan (cid:129) Weiping Pan Coal Fired Flue Gas Mercury Emission Controls 123 JiangWu YanCao ShanghaiUniversityofElectricPower WesternKentuckyUniversity Shanghai,China Kentucky,KY,USA WeiguoPan WeipingPan ShanghaiUniversityofElectricPower WesternKentuckyUniversity Shanghai,China Kentucky,KY,USA ISSN2197-0238 ISSN2197-0246 (electronic) EnergyandEnvironmentResearchinChina ISBN978-3-662-46346-8 ISBN978-3-662-46347-5 (eBook) DOI10.1007/978-3-662-46347-5 LibraryofCongressControlNumber:2015935425 SpringerHeidelbergNewYorkDordrechtLondon ©ShanghaiJiaoTongUniversityPress,ShanghaiandSpringer-VerlagBerlinHeidelberg2015 Thisworkissubjecttocopyright.AllrightsarereservedbythePublishers,whetherthewholeorpartof thematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation, broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionorinformation storageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodology nowknownorhereafterdeveloped. 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Printedonacid-freepaper Springer-VerlagGmbHBerlinHeidelbergispartofSpringerScience+Business Media(www.springer. com) Preface Mercury (Hg) is considered as a global pollutant and is one of the most toxic heavy metals commonly found in the global environment including lithosphere, hydrosphere, atmosphere and biosphere, which has a long residence time in the atmospherefrom0.5to2years.Coalcombustion,wasteincineration,metalmining, refining and manufacturing and chlorine-alkali production are currently major anthropogenicsourcecategoriesintheindustrializedworld. Coal-fired power plants have been considered to be the primary anthropogenic source of mercury into the atmosphere. After inhalation of Hg by human beings, elementalHgvaporrapidlydiffusesthroughthealveolarmembraneandisabsorbed through the lungs, and has a bad effect on the nervous system, particularly with regard to early-life neurodevelopment. Therefore, the research on mercury in America and Europe has been widely conducted. Anthropogenic emissions of mercury still increase in Asia because of increased burning of coal and increased industrialization. Duringcoalcombustionatacoal-firedpowerplant,themercury(Hg)incoalis volatilizedandconvertedtoelementalmercury(Hg0)vaporinthehightemperature regionsofcoal-firedboilers.Asthefluegasiscooled,aseriesofcomplexreactions begintoconvertHg0tooxidizedmercury(Hg2C)compoundsand/orHgcompounds (Hg ) that are in a solid-phase at flue gas cleaning temperatures or Hg that is p adsorbedontothesurfaceofotherparticles.CoalFiredDerivedFlueGasMercury Measurement mainly includes Ontario Hydro Method (OHM), Semi-Continuous EmissionMonitor(Hg-SCEM)andAppendixK.Thecomparisonbetweendifferent mercury emission measurement methods have been investigated in detail in this book. Theauthorshaveinvestigatedtheeffectofhalogenonmercuryspeciation;Cl , 2 HCl, and HBr gases were injected in the slipstream reactor by the control of a massflow controller(MFC). HI andHFwereinjectedusingHI andHFsolutions. Moreover, the constituents of flue gas including SOx, NOx, O , H O and fly ash 2 2 havebeencertifiedtoplayanimportantroleinmercuryreactionsinfluegasesfrom coalcombustioninair. v vi Preface A cost-effectivemercuryemission controltechnologyis requiredto reducethe globalemissionofmercury.Oxidizedmercurycanberemovedinthewetfluegas desulfurization(WFGD)facilitiesofcoalcombustionprocesses,andparticle-bound mercury can be captured along with fly ash in electrostatic precipitators (ESP) or baghouses. Due to Hg0 being difficult to control for its insolubility in water, the mercurycontroltechnologiesaretoconvertortransferHg0 intooxidizedmercury orparticle-boundedmercury,whichareeasiertobecontrolledbyexistingAPCDsat coal-firedpowerstations.Bycomparison,thedirectoxidationmethodofinjectinga typeofoxidant,suchasmodifiedactivatedcarbon,flyashandsomenovelsorbents, intofluegastooxidizeHg0appearedtobeasimplermethod. In this book,the authorsset up a lab-scale multiphaseflow reactoranda pilot- scaleslipstreamreactorandconductedsuchevaluationonthetwoscales.Afterthat, somekindsofsorbentswereinjectedatafull-scalepowerstation.Theexperimental results show that the lab- and pilot-scale reactor systems can provide accurate information of sorbent evaluation under flue gas atmosphere. SO in the flue gas 2 was shown to inhibit mercury oxidization and capture. The sorbents have higher mercury capturing efficiency with higher injection rate and longer residence time when other conditions were held constant. In the pilot-scale, four injection ports vertical to the flue gas flow direction could help improve mixture of sorbent and fluegassothatthemercuryremovalefficiencybecamehigher.Thepilot-scaledata can be used to predict the full-scale results. Some of the chemical and physical mechanismsresponsibleforthemercuryremovalofthesorbentswereidentified. We also have designed a pilot-scale coal-combustion furnace and constructed to study the mercury speciation and transformations in the flue gas under dif- ferent conditions. Its purpose was to study the effect of chlorine compounds on mercury speciation and transformation. The addition of chloride additive makes the percentage of both gaseous bivalent and gaseous elemental mercury in the totalmercurydeclineatsomedegree,andpercentageof particlemercuryincrease correspondingly. However, with the increase in additives, the increasing trend of particle mercury became flat gradually and the decreasing of elemental mercury becomesgentlegradually. Another effective method is the oxidation of elemental mercury with oxidants such as HCl or Cl or ozone over a catalyst followed by the removal of oxidized 2 mercury(Hg2C)withscrubbersolutionintheWFGD facilities.TheextentofHg0 oxidation is affected by the presence of coexisting gases such as NH , NO, SO 3 2 and concentration of the oxidant (HCl). Most mercury control technologies have beendevelopedandtestedonconventionalpulverizedcoal(pc)-firedpowerplants. In the next decade, mercury emissions control will be improved on the basis of theexistingtechnologies,whichincludefuel/rawmaterialpretreatment,existingair pollutioncontroldevices(APCDs),mercuryadsorption,andmercuryoxidation. Shanghai,China JiangWu Kentucky,KY,USA YanCao Shanghai,China WeiguoPan Kentucky,KY,USA WeipingPan Contents 1 MercuryandItsEffectsonEnvironmentandHuman’sHealth........ 1 1.1 MercuryEmissionSources............................................. 1 1.2 MercurySpeciationandItsTransportation............................ 3 1.3 TheEffectofMercuryonEnvironmentandHuman’sHealth........ 4 References..................................................................... 13 2 TheStatusofMercuryEmissionfromCoalCombustion PowerStation................................................................. 19 2.1 FlueGasMercuryEmissionandItsSpeciation ....................... 20 2.2 TheStatusofMercuryEmissionintheUSA.......................... 23 2.3 TheStatusofMercuryEmissioninChina............................. 24 2.4 TheStatusofGlobalMercuryEmission............................... 27 References..................................................................... 29 3 Coal-Fired-DerivedFlueGasMercuryMeasurement................... 31 3.1 OntarioHydroMethod(OHM)......................................... 32 3.1.1 IntroductionofOHM........................................... 32 3.1.2 ProcedureandQA/QCofOHM ............................... 32 3.2 SemicontinuousEmissionMonitor(SCEM) .......................... 34 3.2.1 IntroductionofSCEM.......................................... 34 3.2.2 ComparisonBetweenDifferentSCEMMethods ............. 36 3.3 AppendixK(SorbentTrapMethod) ................................... 43 3.4 ComparisonBetween DifferentMercuryEmission MeasurementMethods.................................................. 43 3.4.1 ComparisonBetweenSCEMandOHM....................... 43 3.4.2 Comparison Between OHM, SCEM, andAppendixK................................................. 47 3.5 TheEffectsofMercuryMeasurementsonMercurySpeciation...... 50 References..................................................................... 52 vii viii Contents 4 TheInfluenceFactorsonMercurySpeciation............................ 55 4.1 TheEffectofHalogenonMercurySpeciation ........................ 57 4.1.1 TheEffectofChlorineandChlorideonMercury Speciation....................................................... 58 4.1.2 TheEffectofOtherHalogenonMercurySpeciation......... 61 4.1.3 AdditionofHydrogenBromide(HBr)......................... 62 4.1.4 AdditionofHydrogenIodine(HI)............................. 63 4.1.5 ComparisonofImpactsonHg(0)Oxidation byDifferentHalogenAdditives................................ 64 4.2 The Effect of SO , NOx, and Other Constitutes 2 onMercurySpeciation.................................................. 68 4.2.1 TheEffectofSOxonMercurySpeciation .................... 68 4.2.2 TheEffectofNOxonMercurySpeciation.................... 70 4.2.3 TheEffectofNOandSO onMercuryOxidationbyHCl... 71 2 4.2.4 TheEffectofH OonMercurySpeciation .................... 72 2 4.2.5 TheEffectofFlyAshonMercurySpeciation................. 73 References..................................................................... 74 5 Coal-FiredFlue-GasMercuryControlTechnologies .................... 77 5.1 TheCo-benefitofExistingAirPollutionControlDevices (APCDs)................................................................. 79 5.2 Sorbent Developmentand Its Mercury Emission RemovalEfficiency ..................................................... 84 5.2.1 ActivatedCarbon(AC)andPowderedActivated Carbon(PAC)................................................... 85 5.2.2 ModifiedPowderedActivatedCarbon......................... 88 5.2.3 FlyAsh.......................................................... 95 5.2.4 NovelSorbent................................................... 100 5.3 EvaluationoftheEffectofSorbentInjectiononMercury Removal................................................................. 111 5.4 AdditivesintotheCoalCombustion ................................... 125 5.5 Multi-pollutionEmissionControlTechnology........................ 129 5.5.1 Effects of Spiking Gases on Hg Oxidation withorWithouttheSCRCatalyst ............................. 139 5.6 TheDevelopingTrendofCoal-FiredFlue-GasMercury EmissionControls....................................................... 146 5.6.1 Fuel/RawMaterialPretreatment............................... 146 5.6.2 ExistingAirPollutionControlDevices(APCDs)............. 147 5.6.3 MercuryAdsorption............................................ 147 5.6.4 MercuryOxidation.............................................. 149 References..................................................................... 153 Chapter 1 Mercury and Its Effects on Environment and Human’s Health Abstract Mercury (Hg) is one of the most toxic heavy metals commonly found intheglobalenvironmentincludingthelithosphere,hydrosphere,atmosphere,and biosphere.Hgisreleasedtotheatmospherefromnaturalandanthropogenicsources. Coalcombustion,wasteincineration,metalmining,refiningandmanufacturing,and chlorine-alkali production are currently major anthropogenic source categories in theindustrializedworld. It was estimated that approximately 33 % of these anthropogenic sources are coal-fired combustion sources. Mercury (Hg) is considered as a global pollutant becauseHg0isthepredominantformofatmosphericHg,whichhasalongresidence timeintheatmospherefrom0.5to2years.AfterinhalationofHgbyhumanbeings, elementalHgvaporrapidlydiffusesthroughthealveolarmembraneandisabsorbed through the lungs. While there is a considerable body of experimental evidence on the reproductive effects of organic mercury at relatively low exposures, the availablehumanevidenceisrestrictedtoafewlimitedstudiesreportingfluctuations in fertility and sex ratio in relatively highly exposed groups such as residents of MinamataCityinJapan.Thus,asnotedby,itisconsideredthatthenervoussystem shouldstillbethecriticalendpointofconcern,particularlywithregardtoearlylife neurodevelopment. Keywords Mercury (cid:129) Emission sources (cid:129) Mercury speciation and transporta- tion (cid:129) Environment (cid:129) Health 1.1 Mercury EmissionSources Mercury(Hg)isoneofthemosttoxicheavymetalscommonlyfoundintheglobal environmentincludingthelithosphere,hydrosphere,atmosphere,andbiosphere.A seriesofcomplexchemicaltransformationsallowsthethree-oxidationstatesofHg to cycle in the environment[1]. Most of the Hg encounteredin all environmental media (water/soil/sediments/biota) is in the form of inorganic mercuric salts and organo-mercurics,withthesoleexceptionofatmosphere.ThemercuricsaltsHgCl , 2 Hg(OH) , and HgS are the prevalent forms existing in the environment, and 2 CH HgCl and CH HgOH are main forms of organic compounds, together with 3 3 ©ShanghaiJiaoTongUniversityPress,Shanghai 1 andSpringer-VerlagBerlinHeidelberg2015 J.Wuetal.,CoalFiredFlueGasMercuryEmissionControls,Energy andEnvironmentResearchinChina,DOI10.1007/978-3-662-46347-5_1
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