化学系统工程LCA01

Lifecycleanalysisorlifecycleassessment(LCA)生命周期分析LCAisananalyticaltoolusedtoestimatetheenvironmentalperformanceofaproductoraprocessItisabudgetingmethodthataccountsforallinputs(rawmaterialsandenergy)andoutputs(products,wastematerials,andenvironmentalimpactingcomponentssuchasCO2)1LCAisalsoreferredtoasa‘cradle-to-grave’approachbecauseitfollowsanactivityfromtheextractionofrawmaterials(‘cradle’)tothereturnofwastestotheground(‘grave’)LCACradleGraveCradle-to-grave(从摇篮到坟墓)Cradle-to-gate(从摇篮到工厂大门)2Achemicalproductlifecycleisdescribedasaseriesofstagesstartingwiththeacquisitionorextractionofrawmaterials,followedbychemicalprocessingleadingtomanufacturing,packaginganddistribution.Thefinalstagesincludeproductuse/reusefollowedbythe“endoflife”consistingofdegradation/storageinalandfillLCA3LCALCAattemptstoquantifytheenvironmentalimpactsthroughouttheproductlifecyclebytrackinginputs(e.g.,rawmaterialsandenergy)andoutputsintermsofatmosphericemissions,waterbornewastes,solidwastes,co-productwastesandotherreleasesintotheenvironment4LCA5LCA6LCA7LCAisoftenusedtocomparetheenvironmentalimpactsoftwoormoreproductsorprocessesthroughouttheirlifecycleLCAshouldfollowthegeneralguidelinesestablishedbyISOISO14040definesLCAasafour-stepprocess:LCA3.Impactassessmentphase4.InterpretationphaseGoalandscopedefinitionphase2.InventoryanalysisphaseReviewarticle:Applicationoflifecycleassessmenttochemicalprocesses,ChemicalEngineeringScience,56(2001)2589-26048EnvironmentalimpactsofchemicalmanufacturingChemicalindustry=pollutingindustry?End-of-pipetreatment:wastewater,wastegas,solidwasteWasteminimization;zerodischargeChemicalprocessRawmaterialsProductWaste9CarboncycleNitrogencyclePhosphoruscycleSulfurcycleCyclingofchemicalsinecosystemsWhataretheprincipalchemicalcycles?10DiffusionbetweenatmosphereandoceanCarbondioxidedissolvedinoceanwaterMarinefoodwebsProducers,consumers,decomposers,detritivoresMarinesediments,includingformationswithfossilfuelsCombustionoffossilfuelsincorporationintosedimentsdeath,sedimentationupliftingovergeologictimesedimentationphotosynthesisaerobicrespirationThecarboncycle(marine)11photosynthesisaerobicrespirationTerrestrialrocksSoilwater(dissolvedcarbon)Landfoodwebsproducers,consumers,decomposers,detritivoresAtmosphere(mostcarbonisincarbondioxide)Peat,fossilfuelscombustionofwood(forclearingland;orforfuelsedimentationvolcanicactiondeath,burial,compaction

overgeologictimeleachingrunoffweatheringCombustionoffossilfuelsThecarboncycle(terrestrial)12HumanactivitiesaffectingthecarboncycleActivityWecleartreesandotherplantsthatabsorbCO2throughphotosynthesisfasterthantheycangrowbackWeburnfossilfuelsandwoodEnvironmentalimpactTheactivitiesincreaseatmosphericCO2concentration,resultinginglobalwarming13NO3–

insoilNitrogenFixationbyindustryforagricultureFertilizersFoodWebsOnLandNH3,

NH4+insoil1.NitrificationbacteriaconvertNH4+to

nitrate(NO2–)lossbyleachinguptakebyautotrophsexcretion,death,decompositionuptakebyautotrophsNitrogenFixationbacteriaconvertN2toammonia(NH3);thisdissolvestoformammonium(NH4+)lossbyleachingAmmonificationbacteria,fungiconverttheresiduestoNH3

,thisdissolvestoformNH4+2.NitrificationbacteriaconvertNO2-

to

nitrate(NO3-)DenitrificationbybacteriaNitrogenousWastes,RemainsInSoilGaseousNitrogen(N2)inAtmosphereNO2–

insoil©2004Brooks/Cole–ThomsonLearningThenitrogencycle14HumanactivitiesaffectingthenitrogencycleActivityWeaddlargeamountsofnitrogen-containingcompoundsintotheenvironmentby -burningfuels(NO) -dischargingnitrogencontainingcompoundstowaterways -applyingfertilizerstosoil(ThisaddsN2Otoatmosphereandexcessnitratestoaquaticsystemsthroughagriculturalrunoff)EnvironmentalimpactLeadstoairandwaterpollutionAffectsbiodiversityofecosystemsbyshiftingspeciescompositiontowardsspeciesthatcanthriveonincreasedsuppliesofnitrogennutrients15GUANOFERTILIZERROCKSLANDFOODWEBSDISSOLVEDINOCEANWATERMARINEFOODWEBSMARINESEDIMENTSweatheringagricultureuptakebyautotrophsdeath,decompositionsedimentationsettlingoutweatheringleaching,runoffDISSOLVEDINSOILWATER,LAKES,RIVERSuptakebyautotrophsdeath,decompositionminingminingexcretionexcretionupliftingovergeologictimeThephosphoruscycle16HumanactivitiesaffectingthephosphoruscycleActivityEnvironmentalimpactWeminelargequantitiesofphosphaterocktomakefertilizersWeaddexcessphosphatestoaquaticsystemsthroughagriculturalrunoffSpeedsuptheflowofphosphorusfromlandtoaquaticsystemsLeadstowaterpollution17SulfurHydrogensulfideSulfatesaltsPlantsAcidicfogandprecipitationAmmoniumsulfateAnimalsDecayingmatterMetallicsulfidedepositsOceanDimethylsulfideSulfurdioxideHydrogensulfideSulfurtrioxideSulfuricacidWaterAmmoniaOxygenVolcanoIndustriesThesulfurcycle18HumanactivitiesaffectingthesulfurcycleActivityEnvironmentalimpactWeburnsulfur-containingcoalandoiltoproduceelectricpowerWerefinesulfur-containingpetroleumtomaketransportfuelsWeconvertsulfur-containingmetallicmineraloresintousefulmetalsAllthreeactivitiesaddsulfurdioxidetotheatmosphere,resultinginairpollution19WaterPollutionTypesandsourcesofwaterpollutantsPollutionofsurfacewaterPollutionofgroundwater20TypesofwaterpollutantsWhatisapollutant?AsubstanceatgreaterthanbackgroundlevelsthathasadetrimentaleffectonlivingorganismsChemical

Organic:oxygendepletingsubstances,oilandgrease, hydrocarbons,pesticides,herbicides

Inorganic:nutrients(nitrate,phosphate),heavymetals, radionuclidesPhysical

Sediment,heat(thermalpollution)Biological

Pathogens21SourcesofwaterpollutionPointsourcesdischargepollutantsatspecificlocationsthroughdrainpipesorsewerlinesintowaterways;example:factoriesNonpointsourcesarescatteredandcannotbetracedtoanysinglesiteofdischarge;example:runofffromcroplandsMajorsourcesofwaterpollution:agriculture,industries,andmining22CleanZoneDecompositionZoneSepticZoneRecoveryZoneCleanZoneNormalcleanwaterorganisms(trout,perch,bass,mayfly,stonefly)Trashfish(carp,gar,leeches)Fishabsent,fungi,sludgeworms,bacteria(anaerobic)Trashfish(carp,gar,leeches)Normalcleanwaterorganisms(trout,perch,bass,mayfly,stonefly)8ppmDissolvedoxygen(ppm)Biologicaloxygendemand8ppmTypesoforganismsPollutionofsurfacewater:streamsMajorconcern:dischargeofoxygen-demandingsubstances,BOD/CODEffect:oxygensag23Pollutionofsurfacewater:lakesDischargeofuntreatedmunicipalsewage(nitratesandphosphates)NitrogencompoundsproducedbycarsandfactoriesDischargeoftreatedmunicipalsewage(primaryandsecondarytreatment:nitratesandphosphates)Dischargeofdetergents(phosphates)Manurerunofffromfeedlots(nitrates,phosphates,ammonia)Dissolvingofnitrogenoxides(frominternalcombustionenginesandfurnaces)Runoffanderosion(fromcultivation,mining,construction,andpoorlanduse)Runofffromstreets,lawns,andconstructionlots(nitratesandphosphates)LakeecosystemnutrientoverloadandbreakdownofchemicalcyclingNaturalrunoff(nitratesandphosphatesNaturalrunoff(nitratesandphosphatesInorganicfertilizerrunoff(nitratesandphosphates)LakewaterisnotmixedwellandhaslittleflowMajorconcern:dischargeofnutrientsEffect:eutrophication(富营养化)24Eutrophication:densegrowthsoforganismsandaquaticplantsduetoexcessiveinputsofnutrients(nitratesandphosphates)SunlightMuchshorevegetationLimneticzoneProfundalzoneEutrophiclakeHighconcentrationofnutrientsandplanktonDensefishpopulationWidelittoralzoneGentlyslopingshorelinesSilt,sand,claybottom25Eutrophication:excessiveplant(algae藻类)growthinrivers,lakes,coastalareasEutrophicationoflakesDepletionofoxygenDeadzonesAlgalbloomRedtidecausedbyphytoplanktonthatproducesapotentpoison26EutrophicationinChinaTaihu,July2007Qingdao,July200827AirpollutionWhatlayersarefoundintheatmosphere?Whatarethemajoroutdoorairpollutants,andwheredotheycomefrom?Whataretwotypesofsmog?Whatisaciddeposition,andhowcanitbereduced?Whataretheharmfuleffectsofairpollutants?28TheatmosphereConsistsofseverallayersTroposphereExtendsto17kmabovesealevel75-80%ofthemassofearth’sair99%ofairconsistsofN2(78%)andO2(21%)StratosphereExtendsfrom17-48kmaboveearth’ssurfaceearth’sglobalsunscreenOzonecreatedwhenoxygenmoleculesinteractwithUVradiation29AveragedistributionandconcentrationsofozoneinthetroposphereandstratosphereBeneficialozoneinthestratosphereprotectslifeonearthbyfilteringoutmostoftheincomingharmfulUVradiationemittedbythesunHarmfulorphotochemicalozoneinthetroposphereoccurswhenvariousairpollutantsthatundergochemicalreactionsundertheinfluenceofsunlightOzonehere,neartheearth’ssurface,damagesplants,lungtissue,andsomematerialssuchasrubberAltitude(kilometers)Ozoneconcentration(ppm)Altitude(miles)StratosphericozoneStratosphereTroposphere4035302520151050051015200510152025Photochemicalozone30Airpollutionisthepresenceofoneormorechemicalsintheatmosphereinsufficientquantitiesanddurationtocauseharmtolifeandmaterialsand/oraltertheclimateMajorclassesofairpollutantsClassExamplesCarbonoxidesCarbonmonoxide(CO)andcarbondioxide(CO2)SulfuroxidesSulfurdioxide(SO2)andsulfurtrioxide(SO3)NitrogenoxidesNitricoxide(NO),nitrogendioxide(NO2),nitrousoxide(N2O)(NOandO2oftenorlumpedtogetherandlabeledNOx)Volatileorganiccompounds(VOC)Methane(CH4),propane(C3H8),chlorofluorocarbons(CFC)Suspendedparticulatematter(SPM)Solidparticles(dust,soot,asbestos,lead,nitrate,andsulfatesalts),liquiddroplets(sulfuricacid,PCBs,dioxins,andpesticides)PhotochemicaloxidantsOzone(O3),peroxyacylnitrates(PANs),hydrogenperoxide(H2O2),aldehydesRadioactivesubstancesRadon-222,iodine-131,strontium-90,plutonium-239Hazardousairpollutants(HAP)Carbontetrachloride(CCl4),methylchloride(CH3Cl),chloroform(CHCl3),benzene(C6H6),formaldehyde(CH2O2)31PrimaryPollutantsSecondaryPollutantsSourcesNaturalStationaryCOCO2SO2NONO2MosthydrocarbonsMostsuspendedparticlesSO3HNO3H2SO4H2O2O3PANsMostandsaltsNO3–MobileSO42–Primarypollutant–harmfulchemicalemitteddirectlyintotheairbynaturaleventsorhumanactivitiesandoccursinaharmfulconcentrationSecondarypollutant-harmfulchemicalformedintheatmospherewhenaprimaryairpollutantreactswithnormalaircomponentsorotherairpollutants32Carbonmonoxide(CO)Description:Colorless,odorlessgasthatispoisonoustoair-breathinganimals;formsduringtheincompletecombustionofcarbon-containingfuels(2C+O2 2CO).Majorhumansources:Cigarettesmoking,incompleteburningoffossilfuels.About77%(95%incities)comesfrommotorvehicleexhaust.Healtheffects:Reactswithhemoglobininredbloodcellsandreducestheabilityofbloodtobringoxygentobodycellsandtissues.Thisimpairsperceptionandthinking;slowsreflexes;causesheadaches,drowsiness,dizziness,andnausea;cantriggerheartattacksandangina;damagesthedevelopmentoffetusesandyoungchildren;andaggravateschronicbronchitis,emphysema,andanemia.Athighlevelsitcausescollapse,coma,irreversiblebraincelldamage,anddeath.33Nitrogendioxide(NO2)Description:Reddish-brownirritatinggasthatgivesphotochemicalsmogitsbrownishcolor;intheatmospherecanbeconvertedtonitricacid(HNO3),amajorcomponentofaciddeposition.Majorhumansources:Fossilfuelburninginmotorvehicles(49%)andpowerandindustrialplants(49%).Healtheffects:Lungirritationanddamage;aggravatesasthmaandchronicbronchitis;increasessusceptibilitytorespiratoryinfectionssuchasthefluandcommoncolds(especiallyinyoungchildrenandolderadults).Environmentaleffects:Reducesvisibility;aciddepositionofHNO3candamagetrees,soils,andaquaticlifeinlakes.34Sulfurdioxide(SO2)Description:Colorless,irritating;formsmostlyfromthecombustionofsulfurcontainingfossilfuelssuchascoalandoil(S+O2 SO2);intheatmospherecanbeconvertedtosulfuricacid(H2SO4),amajorcomponentofaciddeposition.Majorhumansources:Coalburninginpowerplants(88%)andindustrialprocesses(10%).Healtheffects:Breathingproblemsforhealthypeople;restrictionofairwaysinpeoplewithasthma;chronicexposurecancauseapermanentconditionsimilartobronchitis.AccordingtotheWHO,atleast625millionpeopleareexposedtounsafelevelsofsulfurdioxidefromfossilfuelburning.Environmentaleffects:Reducesvisibility;aciddepositionofH2SO4candamagetrees,soils,andaquaticlifeinlakes.35Suspendedparticulatematter(SPM)Description:Varietyofparticlesanddroplets(aerosols)smallandlightenoughtoremainsuspendedinatmosphereforshortperiods(largeparticles)tolongperiods;causesmoke,dust,andhaze.Majorhumansources:Burningcoalinpowerandindustrialplants(40%),burningdieselandotherfuelsinvehicles(17%),agriculture(plowing,burningofffields),unpavedroads,construction.Healtheffects:Noseandthroatirritation,lungdamage,andbronchitis;aggravatesbronchitisandasthma;shortenslife;toxicparticulates(suchaslead,cadmium,PCBs,anddioxins)cancausemutations,reproductiveproblems,cancer.Environmentaleffects:Reducesvisibility;aciddepositionofH2SO4dropletscandamagetrees,soils,andaquaticlifeinlakes.36Ozone(O3)Description:Highlyreactive,irritatinggaswithanunpleasantodorthatformsinthetroposphereasamajorcomponentofphotochemicalsmog.Majorhumansources:Chemicalreactionwithvolatileorganiccompounds(VOCs,emittedmostlybycarsandindustries)andnitrogenoxidestoformphotochemicalsmog.Healtheffects:Breathingproblems;coughing;eye,nose,andthroatirritation;aggravateschronicdiseasessuchasasthma,bronchitis,emphysema,andheartdisease;reducesresistancetocoldsandpneumonia;mayspeeduplungtissueaging.Environmentaleffects:Ozonecandamageplantsandtrees;smogcanreducevisibility.37SolarradiationUltravioletradiationNONitricoxidePhotochemicalsmogH2OWaterNO2NitrogendioxideHydrocarbonsO2MolecularoxygenHNO3NitricacidPANsPeroxyacylnitratesAldehydes(e.g.,formaldehyde)O3OzoneOAtomicoxygenPhotochemicalsmogisamixtureofprimaryandsecondarypollutantsformedundertheinfluenceofsunlight38Allmoderncitieshavephotochemicalsmog,butitismuchmorecommonincitieswithsunny,warm,dry,climateswithlotsofmotorvehiclesSmoggydayCleardayLosAngeles;Denver;SaltLakeCity;Sydney;MexicoCity;SãoPaulo;Beijing39IndustrialsmogisamixtureofSO2,suspendeddropletsofsulfuricacid,andavarietyofsuspendedsolidparticlesSuspendedparticlesaresmallandlightenoughtoremainsuspendedintheatmosphere40AciddepositionAciddepositionisthefallingofacidsandacid-formingcompoundsfromtheatmospheretotheearth’ssurfaceWetanddrydepositioniscomposedofsecondarypollutants,suchasnitricacid,sulfuricacid,andparticulatesofacid-formingsulfateandnitratesalts41RegionswhereaciddepositionisaproblemHavelargeinputsofairpollutionAresensitiveareaswithsoilsandbedrockthatcannotneutralizeinputsofacidiccompounds42AmbientconcentrationsofSO2in2020,μg/m343AciddepositionandhumansRespiratorydiseasesDecreasedvisibilityDamagetostructures,especiallycontaininglimestoneDecreasedproductivityandprofitabilityoffisheries,forests,andfarmsAciddepositionandaquaticsystemsFishdeclinesAcidshock44EffectsofairpollutiononpeopleRespiratorydiseasesAsthmaLungcancerChronicbronchitisPrematuredeath45CO2emissionsClimatechange(globalwarming全球变暖)fromCO2emissionsIsglobalwarmingrealorfake?Trueorfalse?Factorfiction?46Climatechangevs.globalwarmingClimatechangereferstotherapidchangingoftheclimatethatwe(theplanet)areexperiencingmainlysincethe1900sGlobalwarmingisasignificantincreaseintheplanet'sclimatictemperatureoverarelativelyshortperiodoftimeasaresultoftheactivitiesofhumansWhatisthedifference?Notalltheareasoftheplanetarelikelytoexperienceawarming,someareaswillexperienceacoolingandsoclimatechangeisthemoreappropriatescientificterminology47Globalwarming:realorfake?Ofcourseitisreal!Averageglobaltemperaturesareincreasing;Polaricecapsaremelting;sealevelsarerising48Globalwarming:realorfake?Itisnotreal,globalcoolingisrealItisnotreal,itisjustamoneymakingschemeGovernment:carbontaxesPrivatesector:greentechnologybusinessSometimesreal,sometimesfake“Everythingisfine”“Wearenotheadedforamajorenergycrisis”“Thereisplentyofenergy”49Globalwarming:realorfake?CoolIt:TheSkepticalEnvironmentalist'sGuidetoGlobalWarmingBjornLomborg,2007DanishstatisticianandpoliticalscientistLomborgarguesthatmanyoftheelaborateandexpensiveactionsnowbeingconsideredtostopglobalwarmingwillcosthundredsofbillionsofdollars,areoftenbasedonemotionalratherthanstrictlyscientificassumptions,andmayverywellhavelittleimpactontheworld'stemperatureforhundredsofyearsCoolit:thebookCoolit:themovie50Warmingorcooling?Isthereglobalcooling?Solaractivityisindecline.ThishasledtocoolertemperaturesinthepastThesunisnowheadingtowardsa‘grandminimum’initsoutput,threateningcoldsummers,bitterwintersNewtemperaturedatashowingtheplanethasnotwarmedforthepast15years.Thedatasuggestthatwecouldevenbeheadingforaminiiceage51Globalwarming:realorfake?Factualassertions:humanfossilfuelburningcausesCO2concentrationstoriseCO2isagreenhousegas (CO2moleculeshaveawarmingeffect)Increasingthegreenhouseeffectincreasesaverageglobaltemperatures52Fact1:CO2concentrationsarerisingFrom1700to2006,worldannualcoalproductionincreased800-fold.OtherfossilfuelsarebeingextractedtooTheburningoffossilfuelsistheprincipalreasonwhyCO2concentrationshavegoneup.ThisisafactCO2concentrations(inppm)forthelast1100yearsHistoryofworldcoal&oilproductionexpressedinunitsoftheassociatedCO2emissions53GreenhousegasesFact2:Thegreenhouseeffect:globalwarmingiscausedbyanincreaseinthegreenhouseeffectinthetroposphere54MarsEarthThegreenhouseeffectThegreenhouseeffectisnotabadthingbyitself–it'swhatallowsourplanettostaywarmenoughforlifetosurviveWithoutthegreenhousegasesthesurfacetemperatureoftheplanetwouldbeanaverage–18C!ChillyEarthwithoutthegreenhouseeffectWhatwouldEarthlooklikeifthereweren'tanygreenhouseeffectatall?ItwouldprobablylookalotlikeMarsMarsdoesn'thaveathickenoughatmospheretoreflectenoughheatbacktotheplanet,soitgetsverycoldthere55MajorGreenhouseGasesfromHumanActivitiesGreenhouseGasCarbondioxide(CO2)Methane(CH4)Nitrousoxide(N2O)Chlorofluorocarbons(CFCs)*Hydrochloro-fluorocarbons(HCFCs)Hydrofluorocarbons(HFCs)HalonsCarbontetrachlorideAverageTimeintheTroposphere100–120years12–18years114–120years11–20years(65–110yearsinstratosphere)9–39015–3906542HumanSourcesFossilfuelburning,especiallycoal(70–75%),deforestation,andplantburningRicepaddies,gutsofcattleandtermites,landfills,coalproduction,coalseams,andnaturalgasleaksfromoilandgasproductionandpipelinesFossilfuelburning,fertilizers,livestockwastes,andnylonproductionAirconditioners,refrigerators,plasticfoamsAirconditioners,refrigerators,plasticfoamsAirconditioners,refrigerators,plasticfoamsFireextinguishersCleaningsolventRelativeWarmingPotential(comparedtoCO2)123296900–8,300470–2,000130–12,7005,5001,40056Here,thereisalotofuncertainty.ClimatescienceisdifficultTheclimateisacomplex,andexactlyhowmuchwarmingCO2-doublingwouldproduceisuncertainTheconsensusofthebestclimatemodelsseemstobethatdoublingtheCO2concentrationwouldbumpuptheglobalmeantemperaturebysomethinglike2to4degCProbabledrasticeffects:“icecapwouldgraduallymelt,and,overaperiodofafew100years,sea-levelwouldrisebyabout7metersFact3:Increasingthegreenhouseeffectincreasesaverageglobaltemperatures?57Articleonglobalwarmingwrittenbyachemicalengineeringprofessor(lotsoftechnicaldetails):Insightsonglobalwarming,AIChEJournal,57(2011)3259-328458Effectsofglobalwarming:sealevelsAsaresultofglobalwarming,glaciersandiceshelvesaroundtheworldcouldbegintomeltToday,Arcticiceishalfasthickasitwas30yearsagoandtheareacoveredbytheicecaphasshrunkby10%.Ifthemeltingcontinues,therecouldbenoiceinthesummerby2070Animmediateresultofmeltingglacierswouldbeariseinsealevels,andmanycoastalareaswouldcompletelydisappearbeneaththeocean59ItseemsthatclimaticchangesarealreadyaffectingthepatternofElNiñoweathereventsmakingthemmorefrequentandmoreintense.TheIPCCsuggeststhatglobalwarmingcouldtriggermoreextremeweatherevents-floods,droughts,etcThemostdevastatingeffects,andalsothehardesttopredict,wouldbetheeffectsontheworld'slivingecosystems.Manyecosystemsareverydelicate,andtheslightestchangecankilloffseveralspeciesaswellasanyotherspeciesthatdependonthem.Mostecosystemsareinterconnected,sothechainreactionofeffectscouldbeimmeasurableEffectsofglobalwarming:weatherandecosystems60Effectsofglobalwarming:societyThehumancostofglobalwarmingishardtoquantifyGlobalwarmingcouldsparkregionalconflictsaslargenumbersofenvironmentalrefugeesaredrivenfromtheirhomesThousandsoflivesperyearcouldbelostastheelderlyorillsufferfromheatstrokeandotherheat-relatedtrauma.CitieslikeAthens,Chicago,Milan,