ImpactofBiomassandMainBiomassComponentsonCoalReactivityunderOxy-CombustionConditionsAComparisonofPhysicochemicalCharPropertiesObtainedunderN2andCO2Atmospheres
YuliBetancur,?AstridSanchez,?AgustínBueno-Lopez,§andDianaLopez*,?
?QuímicadeRecursosEnergeticosyMedioAmbiente,InstitutodeQuímica,FacultaddeCienciasExactasyNaturales,UniversidaddeAntioquia,UdeA-Colombia,Calle70No.52-21,Medellín,Antioquia,Colombia
?EscueladeQuímica,UniversidadNacionaldeColombia-SedeMedellín,Calle59ANo.63-20,Medellín,Antioquia,Colombia§DepartamentodeQuímicaInorganica,UniversidaddeAlicante,CarreteradeSanVicentes/n,E03080,Alicante,Espana
INTRODUCTION
Coalhasbeenoneofthemostemployedsourcesforenergyproductionworldwide,duetovariousadvantagessuchasitsavailability,abundance,andrelativelylowcostwithrespecttootherfuels.1However,duringthermochemicaltransformationprocessessuchaspyrolysis,combustion,andgasi?cation,pollutantgases,includingCO2,themaincontributortoclimatechanges,arereleasedtotheenvironment.2Severalstudieshavebeenfocusedontheuseofdi?erentalternativesinordertoreduceCO2emissions.SomeofthemmakeCO2captureeasier,forexample,precombustion,postcombustion,andoxy-combustionprocesses.3
Oxy-combustioninvolvesthecombustionofafuelinamixtureofoxygen(insteadofair)andrecycled?uegas,whichconsistsmainlyofCO2andH2O;4aswateriscondensedbeforerecirculation,ahighlyconcentratedCO2(95%)?uegasisproduced.2Thistechnologyisoneofthemostpromisingsinceithasseveraladvantagesintermsofe?ciency,emissionsreduction,adaptabilitytoexistingplants,andeasyCO2separationfromotherexhaustgases.5,6
Nevertheless,duetodi?erencesinphysicochemicalproper-tiesofN2andCO2,thecharacteristicsandbehaviorofcoalontheoxy-combustionprocesshaveadi?erentbehaviorregardingcoalconventionalcombustion.Forinstance,thehigherspeci?cheatofCO2comparedtoN2resultsinalowerreactiontemperatureandthereforecoalignitionisdelayed.Thesecharacteristicscouldalsobeassociatedwiththeendothermicityofthegasi?cationreactionsthataretakingplace.7Additionally,theO2di?usionratethroughCO2islowerthanthatinN2,whichmakescharoxidationslower.8
Currently,biomasshasbeenusedasfuelduetoreductionofCO2emissions,whencomparedtocoal;additionally,ithaslow
?XXXXAmericanChemicalSocietynitrogenandsulfurcontent,resultinginlowerNOxandSOxlevelscomparedwithcoal.9However,theobtainedenergywhenbiomassisburnedaloneisnotenoughcomparedwithcoalcombustionbecauseofitshighvolatilematter,moisturecontent,andlowercalori?cvalue.10Co-?ringofbiomassandcoalinexistingpowerplantsisoneofthemostattractivewaystomitigateCO2emissionswhiledecreasingdependenceonfossilfuels.11Severalstudieshaveevaluatedthecopyrolysisofcoalwithdi?erenttypesoflignocellulosicbiomassincludingricestraw,pinechips,corn,andsugarcane.12?14Resultsshoweddi?erentthermalbehaviorbecauseofthediversityineachbiomasscomposition.Decompositionofbiomassoccursatlowertemperaturesthancoal,probablyduetotherelativelyweakerchemicalbondspresentinlignocellulosicbiomasscomparedtopolycyclicaromatichydrocarbonsincoal.15Ontheotherhand,thehigherH/Cratioofbiomasscomparedwithcoalcouldfacilitatethecoaldecomposition,16whichsuggestedpossiblesynergistice?ectsbyco?ringbiomassandcoal,especiallyincopyrolysisandcogasi?cationprocesses.16?20Nevertheless,anumberofstudieshavedisagreedthepossiblesynergistice?ectusingcoal/biomass(C/B)blends.15,21,22Thecontroversymightbeassociatedwiththematerialusedandbiomassratiointheblend,aswellastheoperatingconditions.12,16,22TheuseofC/Bblendsunderoxy-combustionhasgainedimportanceduetotherelativelyeasyadaptationofthistechnologyinexistingpulverizedcoalpowerplantswithonlyminormodi?cations.23Di?erencesinthecharacteristicsandReceived:February21,2017Revised:April6,2017Published:April11,2017
ADOI:10.1021/acs.energyfuels.7b00533
EnergyFuelsXXXX,XXX,XXX?XXX
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