entrained-bed携带床

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1、5COMPREHENSIVEMODELING5.1INTRODUCTION5.1.1Background(i)KeyModelPremisesSmootandSmithsuggestedanumberofkeypremisesasafoundationforthedevelopmentofcomprehensivecombustionmodels.Thesepremisesaresummarizedbelowwithillustrativeexamples.premise前提、假设assume假设assumption假设P

2、remise1Theonlystepsthatneedtobeconsideredarethosethatcontroltheprogress.ExampleInentrained-bedcombustion,homogeneouschemicalkineticsareoftenignoredandturbulentmixingisassumedtoberate-limiting.entrained-bed携带床homogeneous同相的、均相的rate-limiting影响速率的kinetics动力学Premise2M

3、odelcomponentscanbeindependentlyinvestigatedandmodelledwithcompetingprocessessuppressedorabsent.competingprocess同时发生影响的suppress抑制ExampleTherateofparticleweightlossduetocoaldevolatilizationcanbemeasuredininertatmosphereswheretheresultingchardoesnotoxidize.Thus,allo

4、ftheweightlosscanbeattributedtodevolatilization,andthekineticsfordevolatilizationininertatmospheresisassumedtoapplyinoxidativeatmospheresalso.char焦炭、炭devolatilization析出挥发分inertatmosphere惰性气氛oxidativeatmosphere氧化性气氛Premise3Individualmodelcomponents(i.e.submodels)ca

5、nbecombinedtogiveatotaldescriptionoftheoverallprocess.ExampleFig.5.1showstherequiredcomponentsforageneralizedmodeloflarge-scale,entrained-bedfurnacesandgasifiersthatisbeingdevelopedatACERC.submodel子模型generalizedmodel通用模型gasifier气化器Premise4Basicratemeasurementsmade

6、inlaminarsystemscanbeappliedtoturbulentflowswhentheeffectsofturbulenceonkineticprocessesaretakenintoaccount.Laminar层流turbulent湍流ExampleKineticmeasurementsmadeinlaminarsystemsfornitricoxideformationareappliedtoentrained-bedcoalcombustionbyconvolvinginstantaneousrea

7、ctionratesoverthestatistics(e.g.mixturefractionprobabilities)oftheturbulencenitricoxideNO2convolve卷instantaneousreactionrate瞬时反应速率mixturefraction混合分数probability概率Premise5Thebehaviorofindividualparticlesordropletscanbeusedtopredictthebehaviorofclustersorcloudsofpar

8、ticlesordropletsinentrained-beds.cluster颗粒团cloudofparticles颗粒云droplet液滴TheLagrangianapproachisoftenusedforparticlesinentrainedcombustion.Individualparti