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大气复习资料一、概念解释（1）Globewarming:GlobalwarmingistheincreaseintheaveragemeasuredtemperatureoftheEarth'snear-surfaceairandoceanssincethemid-twentiethcentury,anditsprojectedcontinuation.（2）VOCs:Volatileorganiccompoundsarethoseorganicliquidsorsolidswhoseroomtemperaturevaporpressurearegreaterthanabout0.01psia(=0.0007atm)andwhoseatmosphericboilingpointsareuptoabout500℉,whichmeansmostorganiccompoundswithlessthan12carbonatoms.（3）Wetscrubber:Adevicethatcollectsparticlesbycontactingthedirtygasstreamwithliquiddrops.ORAdeviceremovesparticulatesfromagassteambybringingtheparticlesintocontactwithaliquid.Theparticlesattachtotheliquidandcanberemovedinaslurrysolution.（4）Temperatureinversions:Itisaphenomenonthatthetemperatureincreaseswiththeheightincreasing.Thatstabilityalsolessenstheexchangeofwindenergybetweentheairlayernearthegroundandhighaltitudewinds.ORAtemperatureinversionsisathinlayeroftheatmospherewherethedecreaseintemperaturewithheightismuchlessthannormal.（5）ESP:Electrostaticprecipitator,whichislikeagravitysetterorcentrifugalseparator,butelectrostaticforcedrivestheparticlestothewall.Anditiseffectiveonsmallparticlesbelowabout5μmindiameter.（6）SNCR:shortof“selectivenon-catalystreduction”.Itistheprocessthatinvolvesinjectingeitherammoniaorureaintothefireboxoftheboileratalocationwherethefluegasis760-1100℃(1,400and2,000°F)toreactwiththenitrogenoxides.Theresultingproductofthechemicalredoxreactioniselementalnitrogen(N2),carbondioxide(CO2),andwater(H2O).（7）SCR:shortof“selectivecatalystreduction”.Itisameansofconvertingnitrogenoxides(NOx),alsoreferredtoasNOxwiththeaidofacatalystintodiatomicnitrogen(N2)andwater(H2O),undertheconditionof320-400℃（600-750℉）6NO+4NH3→5N2+6H2O,4NO+4NH3+O2→4N2+6H2O,2NO2+4NH3→3N2+6H2O.（8）ThermalNO:ThermalNOxreferstoNOxformedbythesimpleheatingofoxygenandnitrogen,eitherinaflameorbysomeotherexternalheating,e.g.,alightingbot.（9）PM2.5:Particlewiththeaerodynamicdiameterlessthan2.5um,whichisalsocalledRespirableParticles.（10）Alternativefuel:Severalotherfuelsexceptofconventionalgasolineanddiesel,whichhavebeenusedformanyyearsinslighutlymodifiedautomobileengines,forreasonsofcostandavailability.（11）A/Fratio:Airtofuelratioforautoengines.ForanyhydrocarbonfuelwithformularCxHy,sonstoichoxygen=x+y/4.Forcompletecombustionofthisfuel,theequationisCxHy+(x+y/4)O2→xCO2+y/2O2,so(A/F)=（12）Leanbum：Leanburnreferstotheuseofleanmixturesinaninternalcombustionengine.Theair-fuelcanbeashighas65:1,sothemixturehasconsiderablylessfuelincomparisontothestoichiometriccombustionratio(14.7:1forpetrol,forexample).（13）Photochemicalsmog:Itisthechemicalreactionofsunlight,nitrogenoxidesandvolatileorganiccompoundsintheatmosphere,whichleavesairborneparticlesandground-levelozone.Photochemicalsmogisalightblueanditisthesecondarypollutantsintheatmosphere.（14）Aerodynamicdiameter:Airborneparticleshaveirregularshapes,andtheiraerodynamicbehaviorisexpressedintermsofthediameterofanidealizedsphericalparticleknownasAerodynamicdiameter.（15）HEPA:HighEfficiencyParticulateAir.Itisatypeofairfilterthatusedforremovingsolidparticlesfromgassteamsthatcontainfewofthem.（16）Plumerise:theplumerisingadistance△habovethetopofthestackbeforelevelingout.（17）PrimaryParticles:Particlesfoundintheatmosphereintheforminwhichtheywereemitted,forexamples,NO,CO,SO2（18）PointSources:smallnumberoflargesourcesthatemitlargeramountspersource,athigherelevations(powerplants,smelters,cementplants,etc.)calledpointsources二、Answerfollowingquestions1)Whicharethemainconstituentsforthegroundlevelozoneformation?Ozoneisformedwhenthefollowingconstituentsarepresent.Nitrogenoxides,VolatileOrganic,Compounds,Sunlight,Hightemperature(18℃)NO+VOC+O2+Sunlight→NO2+O32)Pleaselistfivemajortypesofwetscrubbers.PlateScrubber（板式）；PackedScrubber（填料式）；PreformedSprayScrubber（喷雾式）；Gas-AtomizedSprayScrubber（气体雾化）；CentrifugalScrubber（离心式）；Impingement-EntrainmentScrubber（冲击夹带式）；MechanicallyAidedScrubber（机械辅助式）；MovingBedScrubber（移动床式）。3)HowtocontrolVOCspollutionbyprevention?Twoexamples.Substitution(代替):Replacinggasolineasamotorfuelwithcompressednaturalgasorpropaneisaformofsubstitution.ProcessModification(过程修改):Replacinggasoline-poweredvehicleswithelectric-poweredvehiclesisaformofprocessmodification.Leakage（渗漏）Control:Storinglargeamountsofgasolineinfloatingrooftanks.4)Pleaseintroducetheprocessofforced-oxidationLimestoneWetScrubbingbriefly？SO2+H2O→H2SO3;CaCO3+H2SO3→CaCO3+CO2+H2O;2CaCO3+O2→CaCO45)WhatarethedifferencesbetweenSCRandSNCRinNOxtreatment?(WhatisthemostdifferencespointsbetweenSCRandSNCR?)SCRisacatalystprocesswherethetemperatureisbetween600and750℉.However,SNCRisaprocessthatwithoutcatalystsanditisathighertemperaturebetween1,400and2,000°F.6)CanTWCbeappliedinthetreatmentofdieselexhaust(emissionofdieselengine)?fWhy？·Thecharacteristicofemissionofdieselengine:AmplePMandExcessiveO2,Lowertemperature;·Thedifficultyinthereactionofsolid-gas-solid.NO.1)ThecharacteristicofemissionofdieselengineisamplePM,excessiveO2,andlowertemperature.ButthisisnotTWCreactionconditions.2)Itisdifficulttoreactsolid-gas-solid.Key:Themixtureprocessoffuelandairforgase