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1、Z蒸汽质量流量和热量计量常用方法Commonmethodsformeasuringmassf1owandheatofsteamShanghaiInstituteofAutomaticInstruments&meters,ChenShaohuaMeasurementofsteammassf1owTherearetwocommonlyusedmethodsformeasuringheatenergyinathermodynamicsystemusingsteamasaheatcarrier・Oneisbasedonthequalityofacertainheatcarrie
2、r,andtheotheriscompletelymeasuredbyheat・Atpresent,thedomesticpopularpracticesarestilldominatedbytheformer・Therearetwomethodsformeasuringthemassf1owrateofsteam・Inthermalpowerplants,thedifferentialpressureflowmetermainlyactsasahabitoffollowingthepowersystem.InThermoticsInc,especiallythenew
3、lybuiltThermoticsInc,vortexflowmetermainly.Thetwomethodsofmeasurementhavetheirrespectiveadvantages.1.measurethemassflowofsteamwithadifferentialpressureflowmeterThegeneralexpressionforadifferentialpressureflowmeterisFormula:QMformassf1ow,kg/s:Cistheoutflowcoefficient:Betaisthediameterrati
4、o,beta=d/D;Epsilon1isthepositiveexpansioncoefficientatthepositiveendofthepressureport;Distheopeningdiameterofthethrottlingpieceunderoperatingconditions,m;DeltaPisdifferentialpressure,pa;P1positivesideandfluiddensitypressureontheplane,kg/m3・Informula(1),betaandDareconstants,Candepsiloncan
5、beregardedasconstantsinacertainrangeofflow,soformula(1)canbesimplifiedasIn1Pbymeasuringthrottlepositiveendpressuretakingportontheplaneofsteampressureandtemperatureobtainedcheckmethodofsteamdensitytable・Therefore,thistypeofinstrumentbelongstothederivationmassflowmeter・Inpracticalapplicati
6、on,thetemperatureandpressurenearthemeasuringpointareusuallymeasured・Thecorrespondingdensityisobtainedaftercalculation,andtheinstantaneousmassflowisobtainedbycalculation.Oftenreferredtoastemperatureandpressurecompensation.Duetothenatureandcharacteristicsofsteam,differentcompensationmethod
7、scanbeusedinthesuperheatedstateandsaturatedstate・A一massflowmeasurementofsuperheatedsteamWhenthefluidissuperheatedsteam,p1dependsonthefluidpressureandthefluidtemperatureofPlTl,Plfromthepositiveterminalthrottlepressuretakingport,andtheT1test,consideringtheinfluenceoftempera
