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1、Excerptsfromthisultrasonicreport(UR-234)appearintheProceedingsoftheTexasA&MSymposium(January2002)inthefollowingpaper:”UltrasonicFlowMeasurement:TechnologyandApplicationsinProcessandMultipleVentStreamSituations,”byRobertA.Rabalais,DowChemicalUSA,LouisianaDivision,PlaquemineL
2、AandLarrySims,PanametricsInc.BatonRouge,LA/Houston,TXInstrumentandprocesspersonnelarealwayslookingforabetterwaytomeasureprocessflows.Fromsimplesteamflowstotwo-phaseflowswithentrainedsolids,thesearchisongoingfortechnologythatprovidesbothaccuracyandcosteffectiveness.Withtoday
3、’senvironmentalregulationsrequiringbothmoreandmoreaccurateflowmeasurementsaswellhigh-energycostsmakingfuelconsumptionaprimaryfocus,traditionalmeasurementtechniquesmaybelessthanadequate.Onetechnology,whichisgainingacceptancetomeetthenewneedsintoday’sindustrialmarketplace,ist
4、ransit-timeultrasonicflowmeasurement.(Boxatrightillustratesacommonclamp-onconfigurationforliquids.)Consideredbymanyskepticstobetoo“new”ofatechnology,ithasinfactbeenaroundsincethe1950sorearlierforspecialapplications.Ithasbeenavailablecommercially(atleastinJapan)sincethe1960s
5、.PanametricscommercialflowmeterswereintroducedatanISAShowin1979anditsflaregasultrasonicflowmeterwasintroducedatthisSymposiumin1984bySmallingetal.ApplicationshavegrownrapidlyinrecentyearsasmorepeoplebecameawareTransit-timeultrasonicflowmeters,whenappliedofandconfidentinthepe
6、rformanceoftransittimetofluidsofsufficientlyhighacousticimpedanceZ,usetwoclamp-onorwettedtransducers.Oneultrasonicflowmeters.Besidesspanningtemperaturesisinstalledupstreamandoneisinstalledbetweentheextremesofcryogenic(-200°C)toverydownstreamwithrespecttotheflowdirection.hot
7、(500°C),ultrasonictransittimeflowmetersareEachtransducertransmitscodedsoundpulsesusedwithgases,liquidsandtwo-phasemixtures.receivedbytheothertransducer.ThefluidflowRecently,clamp-onhasbeenextendedeventogasesincreasestheultrasonicsignaltimeofflightinthedirectionofflowanddecr
8、easesthetimeofflightinsteelpipe.Sofar,thislastaspectrequiresthattheagainstthedirec
