绿色能源与环境保护Lecture2

PollutionfromCoalUtilizationLiminChen（陈礼敏）Tel:[phone]E-mail:[e-mail]:B4-505•Introduction•Coalformation•Coalclassification•Coalextraction•Utilization•Pollutionfromcoal•“Cleancoal”technologies•SummaryMainContentsCoalformationCoal,afossilfuel,isthelargestsourceofenergyforthegenerationofelectricityworldwide,aswellasoneofthelargestworldwideanthropogenicsourcesofcarbondioxideemissions.Grosscarbondioxideemissionsfromcoalusageareslightlymorethanthosefrompetroleumandaboutdoubletheamountfromnaturalgas.Coalbeginsaslayersofplantmatteraccumulateatthebottomofabodyofwater.Fortheprocesstocontinuetheplantmattermustbeprotectedfrombiodegradationandoxidization,usuallybymudoracidicwater.ThewideshallowseasoftheCarboniferousperiodprovidedsuchconditions.Thistrappedatmosphericcarboninthegroundinimmensepeatbogsthateventuallywerecoveredoveranddeeplyburiedbysedimentsunderwhichtheymetamorphosedintocoal.Overtime,thechemicalandphysicalpropertiesoftheplantremains(believedtomainlyhavebeenfern-likespeciesantedatingmoremodernplantandtreespecies)werechangedbygeologicalactiontocreateasolidmaterial.CoalFormationCoalformationreliesonthreefactors:“(1)initiation,maintenance,andrepetitionofenvironmentsthatfavorlarge-scaleaccumulationandpreservationofvegetalsediment;“(2)conditionswithinthisdepositionalenvironmentthatfavorbiologicaldegradationandalterationofthevegetalsedimenttopeat[peatification];and“(3)geochemicalprocessesthatinducechemicalcoalificationofthepeattohigher-rankcoal.”DiCiccio,1996•Sedimentburial,subsidenceofpeatbogs–Completelycutsoffcontactwithatmosphericoxygen–Overburden:compactionandsubsidence–Increasepressure,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1000～4000m，温度达到60～50℃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150～200℃后几乎不能生成石油。Petroleum&NaturalGasformationvs.Coalformation•Not-so-well-understooddifferencesinformation:–Organicmatter:•Petroleum&NaturalGas:marineOM•Coal:terrestrialOM–Pressure–Temperature–PresenceofsolutionsCoalcompositioncoalcontainedsignificantcarbon,andsmallerpercentagesoftheelementshydrogen,oxygen,nitrogen,andsulfur.Inorganiccompoundssuchasaluminumandsiliconoxidesconstitutetheash.Theclassificationofcoal•Coalisnothomogeneous…itneedsclassification.•Describesextentofgeologicchangeandmetamorphismsincedepositionaspeat•LowRankHighRankparallels:Lossofrecognizableplantremains(macerals)DullshinylusterIncreasinghardnessIncreasingAshcontentTheclassificationofcoalNameVolatiles%Carbon%Hydrogen%Oxygen%Sulfur%HeatcontentkJ/kgBraunkohle(Lignite)45-6560-756.0-5.834-170.5-328470Flammkohle(Flamecoal)40-4575-826.0-5.89.8~132870Gasflammkohle(Gasflamecoal)35-4082-855.8-5.69.8-7.3~133910Gaskohle(Gascoal)28-3585-87.55.6-5.07.3-4.5~134960Fettkohle(Fatcoal)19-2887.5-89.55.0-4.54.5-3.2~135380Esskohle(forgecoal)14-1989.5-90.54.5-4.03.2-2.8~135380Magerkohle(Nonbakeingcoal)10-1490.5-91.54.0-3.752.8-3.5~135380Anthrazit(Anthracite)7-1291.53.752.5~135300PercentbyweightLignite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LigniteSubbituminousBituminousAnthraciteCoalGrade•Describessize,appearance,weight,structure,cleanliness,heatvalueandburningcharacteristics.A:Superior8%ashB:Good:8-12%ashC:Fair:12-16%ashD:Poor16%ashCoalExtraction•OpenPitMining–Mostmineralsareextractedthisway–Fornear-surfaceorebodies–Seriesof‘benches’arecutSurfaceMiningUndergroundMining–Usedwhenoreisfarbelowsurface–Features:•Verticalshaftorinclinedpassageway•Driftsandcrosscutscreatedtoexposeface–BrokenrockhauledfromfaceanduptothesurfaceUndergroundMining:Drift斜坑采煤UndergroundMining:Slope俯斜式采煤UndergroundMining:Shaft立井开采LongwallMining长壁开采SocialEffects•Minedisasters–Rooffalls,movingcoal,explosionsandother(asof1928theywere:60%,20%,10%,and10%respectively).SafetyMeasuresRockdusting,inspectionofhazardoussites,goodlighting,screeningandmovingpartsofmachinery,markedsafetyexits,andemployatrainedcrewandhospitalroominthemine.OtherUsesofCoalToday•GasificationorHydroliquefaction:blastingcoalwithsteamtoproduceCarbonMonoxideandHydrogengas.ThePiñonPineplantnearReno,Nevada.ConvertsCoalintoHydrogengas.AdvantagesofCoalBurningPowerPlants•Safeburning•HighEfficiency(WorkOutput/WorkInput)OtherUsesofCoalToday•Paper,brick,limestone,andcementindustries.•ResidentialHeating–Coalfurnaceshavebeenreplacedbyoilorgasfurnacesorbyelectricheatpumps.–LessthanonepercentofthecoalproducedintheU.S.todayisusedforheating.MiscellaneousProductsMadefromCoalToday•Carbolicacid•FireProofing•FoodPreservatives•BilliardBalls•Medicines•Perfumes•Bak