application 291 en 2 - krohnekrohne.com/fileadmin/content/files-2/ctry_global/application... ·...

Non-contact Level measurement on asphalt paving mixture storage tanks

•Accuratelevelmeasurementofsticky,viscousproducts•Highreliabilityevenwithhightemperatures,densevapoursandagitation•Reducedmaintenanceduetonon-contactmeasurement

1. Background AnAmericanequipmentsupplieroffersacompleterangeofliquidasphaltconcrete(AC)storagetanksandaccessoriesforpolymermodifiedasphalts.Asphalt,alsocalledbitumen,isasticky,blackandhighlyviscousliquidorsemi-solidthatispresentinmostcrudepetroleums.LiquidACishotandhasalowdielectricconstant,whichdecreasesasthetemperaturegoesup.Inthepast,aTDRguidedradarsystemfromacompetitorhadbeenusedtodeterminethelevelinthetanks.TheTDRcableneededfrequentcleaningwhichwasasafetyhazardbecausethetankswerehotandcouldonlybeaccessedbyclimbing.Anotherimportantdisadvantagewasthatthemeasuredvalueswereunreliableduringthefillingandemptyingprocess.Also,measurementaccuracyforTDRisdependentonthecoatingthicknessonthesensor.Othertechnologiessuchasdifferentialpressureandlaserhadalsobeentestedwithoutsuccess.

2. Measurement requirements

Eachtankhastheshapeofanuprightbarrelwithadiameterofabout3.5mandatotalheightofapprox.15m.Ithasheatingcoilsatthebottomandanagitatorinthecenter.Thereisa150mmthickinsulationalloverthetanktopwhichincludesanozzle(Ø150mm/250mmhigh).Themeasuringdeviceistobeinstalledonthenozzleandgiveaccurateandreliablemeasuringvaluesdespitecondensationfromthehotproduct,itshighviscosityandlowdielectricconstant.

APPLICATION NOTE Chemical Industry

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Inside of an asphalt storage tank: 1 Nozzle2 Insulation3 Agitator4 Heatingcoils

Application 291 EN 2.indd 1 19.11.2010 10:44:10 Uhr

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3. KROHNE solution

OPTIWAVE7300Cnon-contactRadar(FMCW)LevelMeterswithDN80HornAntenna.Connectiontypeis1½NPT.Thepartofthenozzlethatprotrudesfromthetankinsulationhasalsobeeninsulated.Thisnotonlyminimizescondensationoftheheavyasphaltvaporsonthehornantennabutalsopreventsfromcrustingasbitumentendstosolidifyatlowtemperatures.

4. Customer benefits

UsingFMCWradartechnology,themetersmeasureoverawidedynamicrange.Thatiswhyneitherthelowreflectivemediumnorthemovingsurfaceduringthefillingandemptyingofthetankscanaffectthemeasurement.Therequirementsofthecustomerintermsofreliabilityandaccuracyarefullymet.Climbingontopofthetanksforperiodiccleaningisnolongernecessary.Thenon-contactradardevicedoesnotrequireanymaintenance.Thissignificantlyreducestheexpenseand,addingthecompetitivepriceoftheOPTIWAVE7300C,makesitaverycosteffectivesolutionforthecustomer.Beinga2-wiredevice,theinstallationofthemeterneedslesswiringandisverysimpleduetothewizarddrivensetup.

5. Product used

OPTIWAVE 7300 C• Non-contactRadar(FMCW)LevelMeterforliquidsandpastes• 2-wirelooppoweredforminimalwiringexpense• Maintenance-free• Reliableandaccurate(±3mmupto10m)measurementevenintankswithagitatedsurfacesorinternalobjects

• Operatesuptoaprocessconnectiontemperatureof200°C• Measuringrangeupto80m• Dielectricconstant(εrvalue)A1.5• Antennascanbeextendedtosuitanynozzlelength• PACTwareforroutinechecks&commissioning• FMCWtechnology:optimizedcost/performanceratio• Exapprovedforhazardousareas• Optionalantennaheatingsystems• Wizarddrivensetup

APPLICATION NOTE

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Application 291 EN 2.indd 2 19.11.2010 10:44:11 Uhr