化学反应工程Chapter 4

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1、化学反应工程Chapter4IntroductiontoReactorDesign4.1GENERALDISCUSSIONSofarwehaveconsideredthemathematicalexpressioncalledtherateequationwhichdescribestheprogressofahomogeneousreaction.Therateequationforareactingcomponentiisanintensivemeasure,andittellshowrapidlycomponentiformsordisappearsinagivene

2、nvironmentasafunctionoftheconditionsthere,orThisisadifferentialexpression.化学反应工程Inreactordesignwewanttoknowwhatsizeandtypeofreactorandmethodofoperationarebestforagivenjob.Becausethismayrequirethattheconditionsinthereactorvarywithpositionaswellastime,thisquestioncanonlybeansweredbyaproperin

3、tegrationoftherateequationfortheoperation.Thismayposedifficultiesbecausethetemperatureandcompositionofthereactingfluidmayvaryfrompointtopointwithinthereactor,dependingontheendothermicorexothermiccharacterofthereaction,therateofheatadditionorremovalfromthesystem,andtheflowpatternoffluidthro

4、ughthevessel.Ineffect,then,manyfactorsmustbeaccountedforinpredictingtheperformanceofareactor.Howbesttotreatthesefactorsisthemainproblemofreactordesign.化学反应工程Equipmentinwhichhomogeneousreactionsareeffectedcanbeoneofthreegeneraltypes:thebatch,thesteady-stateflow,andtheunsteady-statefloworsem

5、ibatchreactor.Thelastclassificationincludesallreactorsthatdonotfallintothefirsttwocategories.ThesetypesareshowninFig.4.1.化学反应工程Figure4.1Broadclassificationofreactortypes.(a)Thebatchreactor.(b)Thesteady-stateflowreactor.(c),(d),and(e)Variousformsofthesemibatchreactor.化学反应工程Thesteady-statefl

6、owreactorisidealforindustrialpurposeswhenlargequantitiesofmaterialaretobeprocessedandwhentherateofreactionisfairlyhightoextremelyhigh.Supportingequipmentneedsaregreat;however,extremelygoodproductqualitycontrolcanbeobtained.Asmaybeexpected,thisisthereactorthatiswidelyusedintheoilindustry.Th

7、ebatchreactorissimple,needslittlesupportingequipment,andisthereforeidealforsmall-scaleexperimentalstudiesonreactionkinetics.Industriallyitisusedwhenrelativelysmallamountsofmaterialaretobetreated.化学反应工程Thesemibatchreactorisaflexiblesystembutismoredifficulttoana