Chapter 3 Flocculation & Sedimentation 3b

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1、Chapter3Flocculation&Sedimentation3.1Characteristicoffermentationbroth3.2Pretreatmentofthesuspension(fermentationbroth)3.3Flocculation3.4Processestoseparatefermentationbroth3.5Sedimentation9/4/202113.5Sedimentation3.5.1Introduction3.5.2Sedimentationprinciples3.5.3Metho

2、dsandcoefficients3.5.4Productioncentrifuges:comparisonandEngineeringAnalysis3.5.5Ultracentrifugation3.5.6Sedimentationatlowacceleration3.5.7Selectionofcentrifuges9/4/202123.5.1IntroductionDefinitionSedimentationisthemovementofparticlesormacromoleculesinaninertialfield.

3、GravitationalorcentrifugalfieldOrmoredetailly:Whenasuspensionisallowedtostand,thedensersolidsslowlysettletothebottomofthecontainerundertheinfluenceofgravityorcentrifugal.Then,thisprocessiscalledsedimentation.3.5Sedimentation9/4/202133.5.1Introduction2.Mainapplicationso

4、fsedimentationExtremelywidespreadapplications!WastewatertreatmentClinicalanalysisClarificationofbrothsorlysatesCellorinclusionbodycollectionDensitydetermination3.5Sedimentation9/4/202143.5.1Introduction3.5Sedimentation9/4/202153.5.2Sedimentationprinciples1.MotionEquati

5、onofFreesettlingCentrifugalfield:Gravitationalfield:FbRFdRd=2RFIRα:particleradiusρ:density9/4/20216Centrifugalfield:Gravitationalfield:DragforcecoefficientFbRFdRd=2RFIR3.5.2Sedimentationprinciples9/4/202173.5.2SedimentationprinciplesStokesregime(Re<0.4):Allenregime(0.

6、4

7、nto:Or:3.5.2Sedimentationprinciples9/4/202111Ifaparticlestartsatrestwithrespecttothefluidinwhichitisimmersedandisthenmovedthroughthefluidbyanexternalforce,itsmotioncanbedividedintotwostages:thefirststageisashortperiodofacceleration,duringwhichthevelocityincreasesfromz

8、erototheterminalvelocity.Thesecondstageistheperiodduringwhichtheparticleisatitsterminalvelocity(终端速度或自由沉降速度).FdRFiRFb