API机械密封冲洗方案

©2001JohnCraneEAA1APIPipingPlansAPI冲洗方案November2004JCTianjinTrainingModule4.3SealEnvironment密封环境APIPipingPlansAPI冲洗方案Integral(internal)recirculationfrompumpdischargetosealAdvantage-NoexternalpipingLimitations-Changingflowraterequireddismantlingofpump-ForcleanpumpagesonlyAPIPipingPlansAPI冲洗方案PointstoNoteforAPIPlan02:-Theinjectiontappingisusedforventingpriortostart–up.-APIplan02isoftenusedtogetherwithplan62,especiallyonhightemperaturebellowsseals.APIPipingPlansAPI冲洗方案Noflushingtothemechanicalseal(‘dead-ended’)PointstoNoteforAPIPlan11:-Useanorificetorestricttheflowrateifthedischargepressureis3barhigherthansealchamberpressure.-UseoncleanandlowabrasivesdutiesAPIPipingPlansAPI冲洗方案SealFlushingBy-PassfromDischarge单密封通过出口进行冲洗RecirculationfromsealchamberthroughaflowcontrolorificeandbacktopumpsuctionPointstoNoteforAPIPlan13:-Useanorificetorestricttheflowrateifthesealchamberpressureis3barhigherthansuctionpressure.-handleabrasivesdutybetterthanAPIplan11-highersealchamberpressuretosuppressvaporisationAPIPipingPlansAPI冲洗方案+=PointstoNoteforAPIPlan14:-Flowbacktosuctionsidewillevacuatevapoursthatmaycollectinsealchamber.-Recommendedforlighthydrocarbonservice.APIPipingPlansAPI冲洗方案RecirculationfrompumpdischargethroughaflowcontrolorificeandcoolertosealOpenLoopCoolingCircuitCoolingWaterOutletCoolingWaterInletAPIPipingPlansAPI冲洗方案RecirculationfromapumpingringinthesealchamberthroughcoolerandbacktosealClosedLoopCoolingCircuitThroatbushingSuctionDischarge18-24VentathighestpointofthepipingCoolingWaterOutletCoolingWaterInletmechanicalsealwithpumpingringHeatexchangerAPIPipingPlansAPI冲洗方案PointstonoteforAPIPlan23:Thermosyphondesign*heatexchanger18to24abovepumpcentreline.*Preventoverheatinginstandbyandstart–up.Installclosefittingneckbushingatthebottomofsealchambertoisolatetheheatfromtheimpellerend.Usedonhightemperatureapplicationstominimiseheatloadonthecoolerbycoolingonlysmallamountofliquidthatisrecirculated.ForhightemperatureboilerfeedpumpapplicationsOtherapplications*hightemperatureliquidclosetobubblepoint.APIPipingPlansAPI冲洗方案RecirculationfrompumpdischargethroughacycloneseparatordeliveringcleanfluidtothesealandfluidwithsolidsbacktopumpsuctionlineCleanoverflowUnderflowInletAPIPipingPlansAPI冲洗方案PointstoNoteforAPIPlan32:-Choseapropersourceofsealflushtoeliminatethepotentialforvaporisationoftheinjectedfluidandtoavoidcontaminationofthefluidbeingpumpedwiththeinjectedflush.-Installalabyrinthbushingatthebottomofthestuffingboxtocontroltheflushingandpressureifnecessary.APIPipingPlansAPI冲洗方案SingleSealFlushingfromExternalSource单密封通过外部来源进行冲洗ThroatBushingRecirculationfrompumpdischargethroughacycloneseparatordeliveringcleanfluidthroughacoolerandthentosealandfluidwithsolidsbacktopumpsuctionlineCoolingWaterOutletCoolingWaterInletAPIPipingPlansAPI冲洗方案NeedlevalveExternalreservoirprovidingadead-endedblanketoffluidtothequenchconnectionofthegland.PointstoNoteforAPIPlan51:--Deadendedblanketonatmosphericsideofsealtopreventfreezingofmoisture.Sealfacewillnotsticktogetherwhenthepumpstarted.Typicalapplication:Pumpoperatingbelow0°C--API6108thEditionhaseliminatedthispipingplan.APIPipingPlansAPI冲洗方案APIPipingPlansAPI冲洗方案Afluidusedasalubricantorbufferbetweendualmechanicalseals.Thebufferfluidisalwaysatapressurelowerthanthepumpprocesspressurebeingsealed.Afluidwhichisintroducedbetweendualmechanicalsealstocompletelyisolatethepumpprocessliquidfromtheenvironment.Pressureofthebarrierfluidisalwayshigherthanthepumpprocesspressurebeingsealed.ThepurposeoffluidcirculationistoremoveheatfrommechanicalsealAPIPipingPlansAPI冲洗方案PumpingringPumpOnapplicationsbelowambienttemperature,circulationofbarrierfluidmaynotbedesirable.Theatmospherewillheatthereservoirandconsequentlyaddheattothesealarea.T2T1Fluidcirculationbytemperaturedifferencebetweenthesealandreservoir.Highertemperatureliquidatsealhaslowerdensityrisestothereservoir.Lowertemperatureliquidatreservoirhashigherdensityfallstothesealtoprovidecooling.APIPipingPlansAPI冲洗方案PointstoNoteforAPIPlan52:TypicallyusedwithanArrangement2unpressuriseddualseal.Duringnormaloperation,circulationismaintainedbyaninternalpumpingring.Thereservoirisusuallycontinuouslyventedtoavapourrecoverysystemandismaintainedatapressurelessthanthepressureinthesealchamber.PressureGaugeLevelGaugeFillvalveOrificeDrainLevelSwitch(H)LevelSwitch(L)PressureSwitch(NormallyOpen)VentvalveExternalreservoirprovidingbufferfluidfortheoutersealofanunpressuriseddualsealarrangement.APIPipingPlansAPI冲洗方案PressureGaugeLevelGaugeLevelSwitch(L)VentValve(NormallyClose)OrificePressureSwitchExternalPressureSourceOne-wayBlockValve(NormallyOpen)PointstoNoteforAPIPlan53:TypicallyusedwithanArrangement3pressuriseddualseal.Duringnormaloperation,circulationismaintainedbyaninternalpumpingring.Thereservoirpressureisgreaterthantheprocesspressurebeingsealed.Externalreservoirprovidingpressurisedbarrierfluidfortheoutersealofanpressuriseddualsealarrangement.DrainAPIPipingPlansAPI冲洗方案PointstoNoteforAPIPlan54:TypicallyusedwithanArrangement3pressuriseddualseal.Duringnormaloperation,circulat