水泥预分解窑系统内生料分解、煤粉燃烧与NOX控制研究

华中科技大学博士学位论文水泥预分解窑系统内生料分解、煤粉燃烧与NO,X控制研究姓名：王世杰申请学位级别：博士专业：热能工程指导教师：陆继东20060418INOXNOXNOXNOXNOXNOXNOXKissingerEAIINOXNOXPIVNO3000/NONONONONONONONONONOXNOXIIIABSTRACTNow,theprecalcinerproducttechnologyhasbeendominantincementplantswithrapiddevelopmentofcementindustry.However,thereexistsomequestionswhichneedtobesolvedandimprovedintheprecalcinerproducttechnology.Thecharacteristicsofrawmealdecompositionandpulverizedcoalcombustioncanprovideimportantparametersforthedesign,operationanddevelopmentofprecalciner.Atthesametime,developinglowNOXtechnologyandlowNOXequipmenthavebecometheinexorabletrendwithstrictNOXemissionstandards.Therefore,itissignificanttostudythekineticsofrawmealdecompositionandpulverizedcoalcombustionaswellasNOXformationmechanismandcontroltechnologyforcementprecalcinerproductsystem.AdvanceinkineticsofrawmealdecompositionandpulverizedcoalcombustionaswellasNOXformationmechanismandcontroltechnologyintheworldwasanalyzedinthisdissertation.Itshowedthathowtousesimpleandeffectivemodelstopredicttheconversionratiosofrawmealdecompositionandpulverizedcoalcombustionwasstillanimportantquestionincementindustry.Inaddition,italsoshowedthatalotofforeignresearcherspaidmoreattentiontotheNOXcontroltechnologybutlessonmechanismsofNOXformation,especiallyforcementrotarykiln.Therefore,kineticsofrawmealdecompositionandpulverizedcoalcombustionaswellasNOXformationmechanismandcontroltechnologyforcementprecalcinerproductsystemwerefurtherstudiedincurrentworkwithcombinationmethodsoftheoreticalanalysis,simulatedexperimentsandCFDsimulation.Thisdissertationhascarriedonresearchesontheseveralfollowingrespectsmainly:ThermaldecompositionofseveralkindsofrawmealsandlimestonewereinvestigatedunderpureN2atmospherewiththermo-gravimetre(TG).ThedataprocessingmethodofTGexperimentswasimproved.Moreover,itwasprovedthatthedataprocessingmethodofthreemethodscombinationwasbetterforselectingthemostprobablemechanism.Intermsofmethodimproved,reactivemechanismsandkineticparametersofthermaldecompositionofcementrawmealandlimestonewereobtained.Theresultsindicatedtheshrinkingcylindermodelwithsurfacereactionratecontrollingmechanismwasthebestmodelfittingtheexperimentdata.Besides,itwasalsofoundE(activationenergy)andAIV(pre-exponentialfactor)variedregularlyfordifferentmechanismfunctions,heatingratesandsources.Asuitofsimulatedexperimentequipment,experimentalprocedureanddataprocessingmethodwereestablishedinthisdissertation.Ahightemperaturegas-solidsuspensionreactorwasusedtosimulatethedecompositionofcementrawmeal.Moreover,thereliabledatahavebeenobtainedafterthemeasuredresultswererevisedbytransferfunction.Variousmodelswereappliedtotheexperimentresultsanditwasfoundthattheshrinkingcylindermodelwithsurfacereactionratecontrollingmechanismisthebestmodelfittingtheexperimentdata.Accordingtothemodel,thekineticparameterswereobtained.Atthesametime,thedecompositionkineticsofrawmealswasinvestigatedundervariousconditions(differenttemperature,pressure,atmosphereandparticlesize)inhightemperaturegas-solidsuspensionreactor.Itwasfoundthatexperimentsinhightemperaturegas-solidsuspensionreactorcanrepresentbettertherealdecompositionprocessofrawmealinindustrialprecalciner.Thecharacteristicsandreactionkineticsofseveralkindsofcoalusedincementindustrywereinvestigatedbymeansoftheoreticanalysisandexperimentstudyinhightemperaturegas-solidsuspensionreactor.Theinfluencesofreactionconditions(species,temperatureandparticlesize)oncharacteristicsofcoalwerestudiedinthispaper.Thebestmodelsofcoalcharcombustionfittingtheexperimentdatawereobtained.Thecalculatingmethodofcouplekineticsofcoalandrawmealwasdiscussedtheoreticallyindetail.Inaddition,interactionbetweencoalcharcombustionandrawmealcalcinationshasbeeninvestigatedbyexperimentswithsimultaneousinjection.Theresultsshowedthattheinteractionexistedobviouslyincertaincoalandrawmeal.Therefore,itisnecessarytostudydeeplytheinteractionmechanismandkineticsbetweencoalandrawmeal.Basedontheoryanalysisoflow-NOxburner,atypeoffour-channellow-NOxburnerusedintheheadofrotarykilnwasintroducedtodecreasetheemissionofNOincementindustry.Inordertoanalyzetheeffectsofdifferentmassflowrateofthefourchannelsoflow-NOxburner,accordingtogeometricandflowsimilarity,acoldtestwasputintoeffectandtheoutletflowfieldsofthefour-channellow-NOxburnerweremeasuredwiththePIV(ParticleImageVelocimetry)technology.Bytheexperiments,theappropriateairdistributionschemeswerepresentedforthetypeoffour-channellow-NOxburner.Thechemicalandphysicalprocessesofclinkerformationwereanalyzedindetail.Onthisbasis,aheatfluxfunctionwasintroducedtotakeaccountofthethermaleffectofVclinkerformation.Combiningwithmodelsofgas-solidtwo-phaseflow,heatandmasstransfer,pulverizedcoalcombustionandNOformation,asetofmathematicalmodelsforafull-scalecementrotarykilnwereestablished.IntermsofcommercialCFDcode(FLUENT),thedistributionofgasvelocity,gastemperatureandgascomponents,especiallyNOincementrotarykilnwereobtainedbynumericalsimulationof3000t/drotarykilnwithfour-channelburner.Besides,mechanismsofNOformationandreductionincementrotarykilnweredeep