绿色能源与环境保护Lecture

PollutionfromCoalUtilization,LiminChen（陈礼敏）Tel-mail:liminchenOffice:B4-505,IntroductionCoalformationCoalclassificationCoalextractionUtilizationPollutionfromcoal“Cleancoal”technologiesSummary,MainContents,Coalformation,Coal,afossilfuel,isthelargestsourceofenergyforthegenerationofelectricityworldwide,aswellasoneofthelargestworldwideanthropogenicsourcesofcarbondioxideemissions.Grosscarbondioxideemissionsfromcoalusageareslightlymorethanthosefrompetroleumandaboutdoubletheamountfromnaturalgas.Coalbeginsaslayersofplantmatteraccumulateatthebottomofabodyofwater.Fortheprocesstocontinuetheplantmattermustbeprotectedfrombiodegradationandoxidization,usuallybymudoracidicwater.ThewideshallowseasoftheCarboniferousperiodprovidedsuchconditions.Thistrappedatmosphericcarboninthegroundinimmensepeatbogsthateventuallywerecoveredoveranddeeplyburiedbysedimentsunderwhichtheymetamorphosedintocoal.Overtime,thechemicalandphysicalpropertiesoftheplantremains(believedtomainlyhavebeenfern-likespeciesantedatingmoremodernplantandtreespecies)werechangedbygeologicalactiontocreateasolidmaterial.,CoalFormation,Coalformationreliesonthreefactors:“(1)initiation,maintenance,andrepetitionofenvironmentsthatfavorlarge-scaleaccumulationandpreservationofvegetalsediment;“(2)conditionswithinthisdepositionalenvironmentthatfavorbiologicaldegradationandalterationofthevegetalsedimenttopeatpeatification;and“(3)geochemicalprocessesthatinducechemicalcoalificationofthepeattohigher-rankcoal.”,DiCiccio,1996,Sedimentburial,subsidenceofpeatbogsCompletelycutsoffcontactwithatmosphericoxygenOverburden:compactionandsubsidenceIncreasepressure,temperature,煤的生成过程,煤主要是远古时代的高等植物在地壳运动中被深埋在地下或水中，其残体在缺氧条件下被厌氧细菌生化降解，纤维素、木质素、蛋白质等被分解并聚缩，形成胶体状的腐殖酸。其余具有抗腐能力的部分如树脂、角质、孢子等保留原有形态分散在腐殖酸中，逐步变成含水很多、黑褐色的泥炭。这是成煤的第一阶段泥炭化阶段。经过漫长的地质年代，泥炭在地热和泥沙覆盖层不断增厚或地壳下沉而受压增大的作用下，泥炭层被压实、失水，其化学性质和成分发生变化。泥炭的密度和碳含量相对增加，腐殖酸、水分、氧、氢和甲烷等挥发物逐渐减少。随着泥炭的质变由浅到深，依次形成不同种类的褐煤、烟煤、无烟煤等。这是成煤的第二阶段煤化阶段。,石油的生成过程,石油的生成过程与煤相似。它的形成物质主要是低等动、植物遗体中的脂肪、蛋白质和碳水化合物。这些有机物质的沉积物在地壳长期缓慢下降中不断增厚，或在深水中被沉积保存。同样经历了缺氧或强还原环境中的细菌分解阶段和温度、压力增加条件下的转化阶段，碳和氢的含量富集，形成一种流动或半流动的粘稠性液体。石油的生成条件要求较严格，沉积过程初期，温度和压力不够，不能生成石油。当沉积深度达到10004000m，温度达到6050时有机质生成大量石油。若压力和温度进一步增加，有机质被热分解，如深度超过4000m，温度超过150200后几乎不能生成石油。,Petroleum&NaturalGasformationvs.Coalformation,Not-so-well-understooddifferencesinformation:Organicmatter:Petroleum&NaturalGas:marineOMCoal:terrestrialOMPressureTemperaturePresenceofsolutions,Coalcomposition,coalcontainedsignificantcarbon,andsmallerpercentagesoftheelementshydrogen,oxygen,nitrogen,andsulfur.Inorganiccompoundssuchasaluminumandsiliconoxidesconstitutetheash.,Theclassificationofcoal,Coalisnothomogeneousitneedsclassification.DescribesextentofgeologicchangeandmetamorphismsincedepositionaspeatLowRankHighRankparallels:Lossofrecognizableplantremains(macerals)DullshinylusterIncreasinghardnessIncreasingAshcontent,Theclassificationofcoal,Lignite褐煤，Subbituminous亚烟煤，Bituminous沥青煤，Flamecoal烟煤，Gasflamecoal亚烟煤，Gascoal气煤，Fatcoal肥煤，forgecoal锻造煤炭，Nonbakeingcoal贫煤，Anthracite无烟煤,LigniteSubbituminousBituminousAnthracite,CoalGrade,Describessize,appearance,weight,structure,cleanliness,heatvalueandburningcharacteristics.A:Superior16%ash,CoalExtraction,OpenPitMiningMostmineralsareextractedthiswayFornear-surfaceorebodiesSeriesofbenchesarecut,SurfaceMining,UndergroundMining,UsedwhenoreisfarbelowsurfaceFeatures:VerticalshaftorinclinedpassagewayDriftsandcrosscutscreatedtoexposefaceBrokenrockhauledfromfaceanduptothesurface,UndergroundMining:Drift斜坑采煤,UndergroundMining:Slope俯斜式采煤,UndergroundMining:Shaft立井开采,LongwallMining长壁开采,SocialEffects,MinedisastersRooffalls,movingcoal,explosionsandother(asof1928theywere:60%,20%,10%,and10%respectively).,SafetyMeasuresRockdusting,inspectionofhazardoussites,goodlighting,screeningandmovingpartsofmachinery,markedsafetyexits,andemployatrainedcrewandhospitalroominthemine.,OtherUsesofCoalToday,GasificationorHydroliquefaction:blastingcoalwithsteamtoproduceCarbonMonoxideandHydrogengas.,ThePionPineplantnearReno,Nevada.ConvertsCoalintoHydrogengas.,AdvantagesofCoalBurningPowerPlantsSafeburningHighEfficiency(WorkOutput/WorkInput),OtherUsesofCoalToday,Paper,brick,limestone,andcementindustries.ResidentialHeatingCoalfurnaceshavebeenreplacedbyoilorgasfurnacesorbyelectricheatpumps.LessthanonepercentofthecoalproducedintheU.S.todayisusedforheating.,MiscellaneousProductsMadefromCoalToday,CarbolicacidFireProofingFoodPreservativesBilliardBallsMedicinesPerfumesBakingPowder,RubbercementfertilizerPaintpigmentsSulfurTNTexplosiveLinoleum,CoalCombustionProducts,烟气脱硫产物,CoalCombustionProductUses,FlyAsh:concrete,structuralfill,andwastestabilizationBottomAsh:structuralfill,snowandicecontrol,roadbases,andconcrete.FGDMaterial:wallboardmanufactureBoilerSlag:煤渣blastinggritandroofingapplications,HungryHorseDaminMontanawasbuiltbetween1948and1953withconcretecontaining120,000metrictonsofflyash.,TheBenefitsofUsingCoalCombustionProducts,Environmentalandeconomicbenefits.Reducedminingcosts,disposalcosts,landfillspaceusage.Inconcrete:reductionofCarbonDioxideemissionsbysubstitutingashforPortlandcement.Mines:InjectionofCCPsinabandonedminescontrolssubsidenceandlessensacidminedrainage,AirQuality,EffectsofcoalcombustiononairSulfurDioxide-acidrainFlyash-particulatematterpollutionCleanAirActof1970NationalAmbientAirQualityStandards(NAAQS)3WaystoControlPollutantsPre-CombustionRemovalPost-CombustionRemovalUseofLowSulfurCoal,AirQuality:SulfurContentofCoals,WaterQuality,AcidMineDrainage,WaterQuality,SedimentationControlCleanWaterActNPDESrequiredforminingoperationsCleanupCalciumCarbonateaddedtosomewaterbodiestoraisepH.,FederalEnvironmentalLaws,NationalEnvironmentalPolicyActFederalLandPolicyandManagementActCleanAirActFederalWaterPollutionControlActSafeDrinkingWaterActComprehensiveEnvironmentalResponse,CompensationandLiabilityActManyothers,Whatis“cleancoal”?,Coalisahighlypollutingenergysource.Fromminetosky,itcontaminateseverystepoftheway.Fromaciddrainagefromcoalminespollutingriversandstreams,tothereleaseofcancer-causingdioxinsandothertoxinswhenitisburned,aswellaspollution-forminggasesandfineparticulatesthatwreakhavoconhumanhealth,coalisadirtybusiness.Itisamajorcontributortoclimatechangethebiggestenvironmentalthreatweface.Itisthemostcarbon-intensivefossilfuel,emitting72%morecarbondioxide(themaindriverofclimatechange)perunitofenergythangas.Mercuryisaparticularproblem.AccordingtotheUnitedNationsEnvironmentrogramme(UNEP),mercuryanditscompoundsarehighlytoxicandposeaglobalenvironmentalthreattohumansandwildlife.2Coal-firedpowerandheatproductionarethelargestsinglesourceofatmosphericmercuryemissions.3Therearenocommerciallyavailabletechnologiestopreventmercuryemissionsfromcoal-firedpowerplants.“Cleancoal”istheindustrysattemptto“cleanup”itsdirtyimagetheindustrysgreenwashbuzzword.Itisnotanewtypeofcoal.“Cleancoal”technology(CCT)referstotechnologiesintendedtoreducepollution.Butnocoal-firedpowerplantsaretrulyclean.,“CleanCoal”Technologies,“Cleancoal”technologiesfallintofourmaincategoriescoalwashing,pollutioncontrolsforexistingplants,efficientcombustiontechnologiesandexperimentalcarboncaptureandstorage.1)CoalwashingLowersthelevelofsulphurandmineralsinthecoal.CoalisnotgenerallywashedinNewZealand,althoughSolidEnergyhasacoalwashingfacilitynearitsSpringCreekMine.Itisalsotriallingcoalwashingtechnologiesusingitshigh-sulphurReeftoncoal.,“CleanCoal”Technologies,2)PollutionControlsforExistingPowerPlantsParticulateemissionscanbereducedbyElectrostaticPrecipitators(ESPs)andfabricfilters.ESPsaremostwidelyused.Fluegasesarepassedbetweencollectingplates.Theseattractparticlesusinganelectricalcharge.NOXemissionscanbereducedbyLow-NOXBurners(LNB).ThesereducetheformationofNOXbycontrollingtheflametemperatureandthechemicalenvironmentinwhichthecoalcombusts.SelectiveCatalyticorNon-CatalyticReduction(SCR/SNCR)areexpensiveandlesswidelyused.SO2emissions-canbereducedbyFlueGasDesulpurisation(FGD).WetFGD,orwetscrubbing,ismostcommonandabsorbsSO2usingasulphurabsorbingchemical(sorbent),suchaslime.Traceelementsemissionstheseincludemercury,cadmiumandarsenic.Someemissionscanbereducedbyparticulatecontrols,fluidisedbedcombustionandFGDequipment.ActivatedCarbonInjectionisbeingtrialledtoremovemercury.,“CleanCoal”Technologies,3)EfficientCombustionTechnologiesSupercriticalPulverisedCoalCombustion(PCC)-useshighpressuresandtemperatures.Thiscanincreasethethermalefficiencyoftheplantfrom35%to45%.Thisreducesemissionsaslesscoalisused.FluidisedBedCoalCombustion(FBC)-allowscoalcombustionatrelativelylowtemperatures,whichreducesNOXformation.Asorbentisusedtoabsorbsulphur.Coalgasification-coalisreactedwithsteamandairoroxygenunderhightemperaturesandpressurestoformsyngas(mostlycarbonmonoxideandhydrogen).Syngascanbeburnttoproduceelectricityorprocessedtoproducefuelssuchasdieseloil.IntegratedCoalGasificationCombinedCycle(IGCC)isthetechnologybehindsomeexperimentalzeroemissionprojects.Itisconsideredthemostsuitabletechnologyforpossiblecarboncaptureandstoragebutlessreliablethanotheroptions.InIGCCagasturbineburnssyngastoproduceelectricity.Exhaustheatfromtheturbineisusedtoproducesteamtopowerasteamturbine.IntegratedGasificationFuelCells(IGFC)-azeroemissiontechnologyunderdevelopmentthatdoesawaywiththesteamcycle.Ituseshydrogenfromcoalgasificationinasolidfuelcelltoproduceelectricity.,SupercriticalPulverisedCoalCombustion(PCC),FluidisedBedCoalCombustion(FBC),IntegratedCoalGasificationCombinedCycle(IGCC),IntegratedGasificationFuelCells(IGFC),“CleanCoal”Technologies,4)CarboncaptureandstorageTherearecurrentlynocommerciallyavailabletechnologiestocaptureandstorecarbon.Suchtechnologyisveryexpensiveandisunlikelytobeavailableforatleast20-30years.,Indirectcoaltoliquid,Summary,“Cleancoal”methodsonlymovepollutantsfromonewastestreamtoanotherwhicharethenstillreleasedintotheenvironment.Anytimecoalisburnt,contaminantsarereleasedandtheyhavetogosomewhere.Theycanbereleasedviathefluash,thegaseousairemissions,wateroutflowortheashleftatthebottomafterburning.Ultimatelytheystillenduppollutingtheenvironment.,Questions,Whatarethedifferencesbetweenthepollutionfromoilutilizationandcoalutilization?Giveanexampleonhowtosolvethepollutionfromcoalutilization?LargeamountofCO2emissionduringfossilenergyconsumption,doyouthinkwhatisthemosteffectivewaytosolvethisproblemandwhy?,新的分类国家标准对各类煤的若干特征,1、无烟煤（WY）挥发分低，固定碳高，比重大，纯煤真比重最高可达1.90，燃点高，燃烧时不冒烟。对这类煤，可分为：01号为老年无烟煤；02号为典型无烟煤；03号为年轻无烟煤，无烟煤主要是民用和制造合成氨的造气原料，低灰、低硫和可磨性好的无烟煤不仅可以做高炉喷吹及烧结铁矿石用的燃料，而且还可以制造各种碳素材料，如碳电极、阳极糊和活性碳的原料，某些优质无烟煤制成航空用型煤还可用于飞机发动机和车辆马达的保温。（能源经理人）2、贫煤（PM）变质程度最高的一种烟煤，不粘结或微弱粘结，在层状炼焦炉中不结焦，燃烧时火焰短，耐烧，主要是发电燃料，也可作民用和工业锅炉的掺烧煤。3、贫瘦煤（PS）粘结性较弱的高变质、低挥发分烟煤，结焦性比典型瘦煤差，单独炼焦时，生成的焦粉甚少。如在炼焦配煤中配入一定比例的这种煤，也能起到瘦化作用，这种煤也可作发电、民用及锅炉燃料。,4、瘦煤（SM）低挥发分的中等粘结性的炼焦用煤。焦化过程中能产生相当数量的焦质体。单独炼焦时，能得到块度大、裂纹少、抗碎强度高的焦煤，但这种焦碳的耐磨强度稍差，但2炼焦配煤使用，效果较好。这种煤也可作发电和一般锅炉等燃料，也可供铁路机车掺烧使用。5焦煤(JM)中等或低挥发分的以及中等粘结或强粘结性的烟煤,加热时产生热稳定性很高的胶质体,如用来单独炼焦,能获得块度大、裂纹少、抗碎强度高的焦煤。这种焦煤的耐磨强度也很高。但单独炼焦时，由于膨胀压力大，易造成推焦困难，一般作为炼焦配煤用，效果较好。6、1/3焦煤（1/3JM）中高挥发分的强粘结性煤，是介于焦煤、肥煤和气煤之间的过渡煤种，单炼焦时能生成熔融性良好、强度较高的焦煤，炼焦时这