II pressure relief system flow .pdf

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1、IIPressureReliefSystemFlow:ResultsoftheDIERSPhaseIIProjectsJamesE.HuffChairman,DIERSTechnicalAdvisoryCommitteeforTwo-PhaseFlowProjects1.INTRODUCTION1-1.ScopeThepresenceofbothliquidandvaporphasesmustbeanticipatedintheventstreamfromchemicalreactorsunderrunawayconditions.Thestreamistreated

2、asavapor-liquidmixtureatequilibrium(saturation)conditions.Subcooledliquidcanventinitiallyundercertaincircumstances,butsaturationconditionswillbeattainedasthefluidflowsdownthepipeandastheeventprogresses.Theventstreamquality(weight-flowfractionvapor)canvaryfromzerotoonedependingontheparti

3、cularcircumstances.Thedesignmodelsofthissectionapplyovertheentirerangefromsaturatedliquidtosaturatedvapor.Theconventionaltechnologyforsingle-phaseflowisnotduplicatedhere.Theadiabaticflashingofthefluidasthepressurefallsalongtheflowpathiscomputedbyconventionalflashdistillationmethods.Ades

4、criptionoftherequiredthermophysicalpropertybaseandthecomputationalroutinesispresentedinAppendicesU-AandII-B.Reliefsystemelementsconsideredarepipeandfittings,safetyreliefvalves,rupturediskassemblies,nozzles,orifices,contractionsandenlargements.Fluidtypesrangefromthinsinglecomponentstovis

5、coustwo-liquid-phaseandmulticomponentsystems.Thesubjectofflowregimemapsfortwo-phasesystemsisnotcoveredinthisdocument.SeeReference[1]foradiscussionofflowregimes.Thehighvelocitiesandflashingconditionscommoninreliefsystemsputtheflowinthewell-mixedregimes;equilibrationratesarequiterapidwith

6、respecttofluidresidencetimes.KnowledgeoftheactualflowregimeisnotrequiredfortheuseofthemethodswithinthescopeoftheDIERSprojects.ThemethodspresentedherearefromDIERScontractorreportsandmembercompanyinput.Fauske&Associates,Inc.(FAI)havedevelopedthecom-putercodeforthemodelspresentedintheirrep

7、ortstoDIERS.ThiscodeisintheformofsubroutinestotheDIERS44SAFIRE"program(seeAppen-dixII-Dfordetails).Thetwo-fluidflowmodelusedbyJAYCORintheirinterpretationofDIERStestdata[2,3]isproprietaryandnotincludedhere.1-2.OrganizationSection1ofthischaptercontainsintroductoryinformation.TheR