循环流化床气固传质实验研究.pdf

ChineseJ.Chem.Eng.,10(1)70一78(2002) ExperimentalStudyonGas-SolidMassM-ansferin CirculatingFluidizedBeds* Too 八 WANGLinna(王琳娜)**,MANGLing(张*),JINDongjie(靳东杰)and LIJinghai(李静海) Multi-PhaseReactionLaboratory,InstituteofProcessEngineering(formerlyInstituteofChemicalMetallurgy),Chi neseAcademyofSciences,Beijing100080,China Abstract Thisstudyisdevotedtogas-solidmasstransferbehaviorinheterogeneoustwo-phaseflow.Experiments werecarriedoutinacoldcirculatingfluidizedbedof3.0minheightand72mmindiameterwithnaphthalene particles.Axialandradialdistributionsofsublimatednaphthaleneconcentrationinairweremeasuredwithanon- lineconcentrationmonitoringsystemHPGC-MS.Masstransfercoefficientswereobtainedundervariousoperating conditions,showingthatheterogeneousflowstructurestronglyinfluencestheaxialandradialprofilesofmasstransfer coefficients.Inthebottomdenseregion,masstransferrateishighduetointensivedynamicbehaviorandhigher relativeslipvelocitybetweengasandclusters.Inthemiddletransitionregionandtheupperdiluteregion,asa resultoflowmasstransferdrivingforceandtheinfluenceofflowstructure,masstransferratedistributionbecomes non-uniform.Inconclusion,amongtheoperatingparametersinfluencingmasstransfercoefficients,thesuperficial gasvelocityisthemostimportantfactorandthesolidcirculationrateshouldbealsotakenintoaccount. Keywords masstransfer,circulatingfluidizedbed,gas-solidheterogeneousflow i INTRODUCTION therisercanbecharacterizedwiththecore-annulus Withincreasingapplicationofcirculatingfluidized structurell,3-slthatconsistsofarelativelydilutecore beds(CFBs)inindustries,itisimportanttounder- reg