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1、BrazilianJournalofChemicalISSN0104-6632PrintedinBrazilEngineeringVol.21,No.03,pp.497-507,July-September2004TIMESERIESANALYSISOFPRESSUREFLUCTUATIONINGAS-SOLIDFLUIDIZEDBEDSC.AlbertoS.FelipeandS.C.S.RochaLaboratoryofFluid-DynamicsandDrying-LFS,SchoolofChemicalEngineering,StateUniversityofCampi
2、nasC.P.6066-13083-970,Campinas-SP,BrazilPhone:+(55)(19)3788-3929,Fax:+(55)(19)3788-3922E-mail:severo@feq.unicamp.br,E-mail:rocha@feq.unicamp.br(Received:February13,2003;Accepted:March15,2004)Abstract-Thepurposeofthepresentworkwastostudythedifferentiationofstatesoftypicalfluidization(singleb
3、ubble,multiplebubbleandslugging)inagas-solidfluidizedbed,usingspectralanalysisofpressurefluctuationtimeseries.Theeffectsofthemethodofmeasuring(differentialandabsolute)pressurefluctuationsandtheaxialpositionoftheprobesinthefluidizationcolumnontheidentificationofeachoftheregimesstudiedwereeva
4、luated.FastFourierTransform(FFT)wasthemathematictoolusedtoanalysingthedataofpressurefluctuations,whichexpressesthebehaviorofatimeseriesinthefrequencydomain.Resultsindicatedthattheplenumchamberwasaplaceforreliablemeasurementandthatcareshouldbetakeninmeasurementinthedensephase.Themethodallowe
5、dfluiddynamicregimestobedifferentiatedbytheirdominantfrequencycharacteristics.Keywords:pressurefluctuation,fluidizedbeds,FastFourierTransform,spectralanalysis,timeseriesINTRODUCTIONclassificationonly),bubblingfluidization,sluggingfluidization(narrowvessels),turbulentfluidization,Fluidizatio
6、nisaunitoperationthatinvolvesfastfluidizationandpneumaticconveying(Trnkaetdirectcontactbetweenabedformedoffinesolidsal.,2000).Inaddition,bubblingbedscanbefurtherandtheupwardflowofafluid,liquidand/orgas,dividedintothreedifferentmodesofcontact:singleenhancingheatandmasstransferbetweenthephase
7、sbubble,multiplebubbleandexplodingbubbleinvolved(KuniiandLevenspiel,1991).Fluidized(Johnssonetal.,2000).bedsareusedinavarietyofindustriessuchasthePressurefluctuationisoneofthemostchemical,petroleum,metallurgical,foodandcommonlymeasuredparametersinstudies
