Biomass-pyrolysis---gasification-for-product-gas-p

Biomasspyrolysis/gasificationforproductgasproduction:theoverallinvestigationofparametriceffectsG.Chena,*,J.Andriesa,Z.Luob,H.SpliethoffaaFacultyofDesign,EngineeringandProduction,SectionThermalPowerEngineering,DelftUniversityofTechnology,Mekelweg2,2628CDDelft,TheNetherlandsbInstituteforThermalPowerEngineering,ZhejiangUniversity,YuguRoad20,Hangzhou310027,ChinaReceived28November2001;receivedinrevisedform22April2002;accepted3August2002AbstractTheconventionalbiomasspyrolysis/gasificationprocessforproductionofmediumheatingvaluegasforindustrialorcivilapplicationsfacestwodisadvantages,i.e.lowgasproductivityandtheaccompa-nyingcorrosionofdownstreamequipmentcausedbythehighcontentoftarvapourcontainedinthegasphase.Theobjectiveofthispaperistoovercomethesedisadvantages,andtherefore,theeffectsoftheoperatingparametersonbiomasspyrolysisareinvestigatedinalaboratorysetupbasedontheprincipleofkeepingtheheatingvalueofthegasalmostunchanged.Thestudiedparametersincludereactiontemperature,residencetimeofvolatilephaseinthereactor,physico-chemicalpretreatmentofbiomassparticles,heatingrateoftheexternalheatingfurnaceandimprovementoftheheatandmasstransferabilityofthepyrolysisreactor.Therunningtemperatureofaseparatecrackingreactorandthegeo-metricalconfigurationofthepyrolysisreactorarealsostudied.However,duetotimelimits,differenttypesofcatalystsarenotusedinthisworktodeterminetheirpositiveinfluencesonbiomasspyrolysisbehaviour.Theresultsindicatethatproductgasproductionfrombiomasspyrolysisissensitivetotheoperatingparametersmentionedabove,andtheproductgasheatingvalueishigh,upto13–15MJ/Nm3.
2002ElsevierScienceLtd.Allrightsreserved.Keywords:Biomass;Pyrolysis/gasification;Parameters;Effect;ProductgasEnergyConversionandManagement44(2003)1875–1884*Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](G.Chen).0196-8904/02/$-seefrontmatter
2002ElsevierScienceLtd.Allrightsreserved.PII:S0196-8904(02)00188-71.IntroductionMoreattentionhasbeenpaidinrecentyearstorenewableenergy,especiallybiomassenergy,duetothefactthatincreasingCO2,NOxandSOxemissionsintheatmosphereareresultingfromtheincreasingapplicationoffossilfuelsandmanfearstheiraccompanyingshortageoccurringinthenearfuture.Biomassisarenewableresourceand,comparedwithfossilfuel,hasamuchshorterperiodoflifecycle(lifecycleisheredefinedasthedurationoftheperiodfromthegrowthofbiomasstoitsfinalutilisationbymankind),andtherefore,theapplicationofbiomassforenergycanleadtozeronetCO2emissioninaveryshortlifecycleperiodsincecarbonintheformofCO2andenergyarefixedbyphotosynthesisduringbiomassgrowth.Comparedwithotherrenewableenergyresources,biomassisabundantinannualproduction(upto2740Quads,byNRELweb-site),withageographicallywidespreaddistributionintheworld[1].Agoodsolutionfortechnicalapplicationofbiomassenergyisconversionofbiomassbyapyrolysis/gasificationprocess[2–9].Unfortunately,pyrolysis,especiallyflashpyrolysistechnology,hasbeenconsideredasagoodsolutiontoconvertbiomassonlytoliquidfuel,nottogaseousfuel.Thereasonsthatstronglysupportthisapproacharethatthegasyieldfromconventionalpyrolysistechnologyisverylow,normallybelow40wt.%[10–13]andtheaccompanyingcorrosionisserioustodown-streamequipment,likeagasturbine/engine,causedbythehighcontentoftarvapourcontainedinthegasphase[3].However,pyrolysisgas,comparedwithconventionalgasificationgas,ismoreadvantageous,asitishigherinheatingvalueand,consequently,canbeappliedwelltothedownstreamgasturbineorothercombustionenginesforpowergenerationorusedasasubstituteforcivilgasforcooking.Furthermore,whenintegratedwithgasturbinecombustion,thiskindofgascanovercomethechallengeincurredbycombustionofconventionalgasificationgas[3].Inthelattercase,morefuelgasisneededinordertooperatetheturbinewiththesameturbineinlettemperature,andaccordingly,significantchangesintheturbine
sconfigurationarerequired.Thisworktriestomakepeopleconfidentingasproductionthroughthepyrolysisroute.Thefinalgoalofthecurrentworkisintendedtoincreasetheproductgasproductionfrombiomasspyrolysisinafixedbedreactorand,inparallel,toreducetarcorrosiontodownstreamequipmentbyconvertingtartogasinthepyrolysismechanism.Themainresearchactivitieshereareconcentratedontheparametriceffects,including:reactiontemperature,residencetimeofvapourphases,physico-chemicalpretreatment,heatingrateoftheexternalheatingfurnace,heatandmasstransferabilityofthesetupused,therunningtemperatureofaseparatecrackingreactorandthegeometricalconfigurationofthepyrolysisreactor.2.Experimentalapparatusandmethod2.1.ExperimentalapparatusPyrolysisofbiomassmaterialwasperformedinabatchpyrolysisassemblyasshowninFig.1,whichcancontainupto500gofsawdustfine.Generallyspeaking,thepyrolysisassemblyconsistsofthreeparts:reactorpart(pyrolysisreactor,crackingreactorandheatingfurnace),condenserandpurificationpart(condenserIandII,dryer),andgasstoragepart(gastankorwatertank).Thepyrolysisreactorwasmadeofstainlesssteel(totalheight,750mm;80mmi.d.)andnormally1876G.Chenetal./EnergyConversionandManagement44(2003)1875–1884isimmersedinanexternallyheatedfurnacelined