storedoutside? learntheeffectsunlightcanhaveonyourglycol

Transkript

1 Shouldglycolbe storedoutside? learntheeffectsunlightcanhaveonyourglycol

2 AboutTheCover Afluorophoreabsorbslightenergyofaspecificwavelengthandre-emitslightatalongerwavelength,creatingafluorescent efect.fluorescentdyesarewidelyusedinheattransferfluidapplicationstodetectleaks.the coverpicturedepictssomeofthedyesusedinglycolbasedfluids.thephotographwastakenby addingdropsofthreediferentdyesintoaglycol-watermixture,lightedbya3w LEDUVlampof 395nm wavelength.fluorescencehasmanypracticalapplications,includingmineralogy, gemology,medicine,chemicalsensors(fluorescencespectroscopy),fluorescentlabeling,dyes, biologicaldetectors,cosmic-raydetection,and,mostcommonly,fluorescentlamps.fluorescence alsooccursfrequentlyinnatureinsomemineralsandinvariousbiologicalstatesinmany branchesoftheanimalkingdom. Fluoresceinisoneofthecompoundsusedasafluorescentmaterial.Oneofthefirstusesof fluoresceinwasin1877inamajorground-watertracing experimentinsoutherngermany.theresultsofthis experimentshowedthattheriverdanubeandrhineare connectedbyundergroundstreams.fluoresceinwas placedinthedanubeandabout60hourslateritappearedinanafluentofthe Rhine.10Kilogramsoffluoresceinwereused! Source:Barbieri.,Beniamino,"AShortHistoryofFluorescence",TheFluorescence Foundation,2010.

3 FluidSolutions Edition2,December2016 Copyright 2016byFluidSolutions,Dynalene,Inc Alrightsreserved.Nopartofthispublicationmaybereproduced,distributed,ortransmitedinanyform orbyanymeans,includingphotocopying,recording, orotherelectronicormechanicalmethods,withoutthepriorwritenpermissionofthepublisher,exceptinthecaseofbriefquotationsembodiedincritical reviewsandcertainothernoncommercialusespermitedbycopyrightlaw.forpermissionrequestsortorequestforacopyofthemagazine,pleasecontact orcalusat

4

5 MoltenSalts:Hightemperatureheattransferfluidandthermalstoragemedium

6 MoltenSalts:Hightemperatureheattransferfluidandthermalstoragemedium Dependingonthesaltandthematerialsused,corosion mayalsobeanissue.ifusingnitrateswithstainlesssteel, corosionwilbeminimal,howeverwithmoreaggressive saltsthecorosioncouldbesevere.chloridesandfluorides mustbeusedwithhigheraloysastheywilcorode stainlesssteelsathightemperatures.inmanyheattransfer fluidapplicationscorosioninhibitorsareaddedtothefluid toreducecorosion.corosioninhibitorsareacommon additiveusedtoprotectsystems,astheinhibitorscan easilycoattheinsideofpipingandcomponentswithout afectingtheheattransferperformanceofthefluid. TheGreatSaltLakeisfourto fivetimessaltierthantheocean (orsixtoeighttimessaltierthan theoceanindroughtyears!)and containsabout4.5biliontonsof salt.utahmakesabout$1.3 bilioneveryyearfrom The GreatSaltLake($1.1bilionin mineralextraction,$136milion from recreationand$57milion from harvestofbrineshrimp.)

7

8 ShouldGlycolBeStoredOutside? standardcapliners,andthethreadswerecoatedwith DuPontSevereServiceGreasewithTeflonbeforeclosing thecaps.thesecondtypewas150mlquartzvesselswith quartzlidsfrom AdValueTechnology.Therimsofeachlid werecoatedwiththeteflongreasebeforeclosing,and electricaltapewaswrappedaroundtherim tocompletethe seal. Table1containsasummaryofeachglycolused,along withthecontainertypeandlocation.hdpebotleswere eitherleftfulyexposedtoalsunlight,placedunderabasic glasspetstoreaquarium coatedwithuvfilm by TechnologyLK(Figure2),orcompletelycoveredwith aluminum foil.thequartzvesselswereleftfulyexposed. Wekeptcontrolsamplesinaclosedcabinetinsidethe laboratory.eachsamplewasrunintriplicateforatotalof 75samples,notcountingthecontrols. Aplywoodsheetplacedatanangleheldthefulexposure andfoil-coveredsamplestogether,withwoodentracksto keepthem inplace(figure3).afterplacingthefoilbotles, wespraypaintedtheiruppersurfaceswithmategrey paint.thissetupremainedoutsideforeighteenweeks, from latespringthroughearlyfal.theaquarium setupwas placedrightnexttothisplywoodsheetandstayedoutside forsixteenweeks. Atseveral-weekintervals,weopenedthebotlesto

9 ShouldGlycolBeStoredOutside? degradedsamples.indeed,bytheendoftheexperiment, simplyopeningtherawpg samplebotlesindoorswould causethesmeltospreadthroughtheentirelab.table2 showstheseresultsinasimpleyes/noformat. Ifwelookattheseresultsfurther,wefindthattherewerea limitednumberofsamplesthatendedupwithasignificant odorbytheendoftheexperiment.therawpgs,bothtech anduspgrades,andraweg alhaveastrong, solvent-likesmel.thetwopg typessmelthesame,while theeg isdistinctlydiferent.theinhibitedpgs,againboth techanduspgrades,alsohaveastrongsmel,butthisis asweeter,almostfruityorfloral,smel,unlikethesmelof anyoftherawglycols. WeperformedGCtestingoneachsampleintwoways. First,eachsamplewasrunwiththeGChookeduptoa flameionizationdetector(fid),forthebestpossiblepeak resolutionandseparation,inordertoseeasmany compoundsaswecouldgetoutoftheheadspace.once anynew,non-glycolpeakswereuncoveredthisway,we switchedtothemsdtotrytodeterminetheidentityofthe unknowncompounds. Wechosetodoheadspaceanalysisinordertoavoid dealingwithalargeglycolpeakthatcouldpotentialy swampcontaminantpeaks.sincesomeglycolshad alreadydevelopedastrongodorbyfourweeks,weknew thebreakdownproductswerevolatilesandthusshouldbe easytocaptureinthesampleheadspace.additionaly, injectingonlyvaporratherthanliquidontothecolumn helpstopreventcaryoverfrom runtorun,whichwas beneficialconsideringthelargenumberofsamplestested. TheFIDresultsoftheUVvsnon-UVsamplesarestriking. ThesamplesthatwerenotexposedtoUVrays(the foil-wrappedhdpe,thehdpeprotectedbytheglassand UVfilm combination)givechromatogramsthatlookvery similartothecontrolsamples(figure4).someofthefuly exposedglycolshaveseveralstrongnewpeaks,increasing insizethelongerthesamplesremainedexposed. Interestingly,notalofthefluidsthatwerefulyexposedto sunlightshowednewcompoundsdeveloping.themost afectedsamplesweretherawpropyleneglycols.both techanduspgradeglycolsshowseveralnewpeaksby theendoftheexperiment,withthemostdramaticpeaksat around9and20minutes,alongwithseveralothersmaler peaks.rawethyleneglycolhasnewpeaksat15and17 minutes.rawbioglycolhasonlyafewsmalpeaks(about 9minutes)thatdon tcomecloseinheightorareatothe glycolpeakitself.forbotheg andpg thecontaminant peaksdwarftheoriginalglycolpeakbyanorderof magnitude(figure5). TheinhibitedglycolshavelessgoingonintheirGCcurves (Figure6).InhibitedPG showssomeofthesamenew peaksasrawpg,butnotothers.inhibitedeg doesnot shownewpeakdevelopmentatal. IfwelookattheGC/MSresultswebegintoseethesource ofthediferenceinsmelnotedpreviously.inaloftheraw glycolswithstrongodors,themssoftwareidentified(with> 80% probability)variousdioxolanecompounds,asshown

10 ShouldGlycolBeStoredOutside?

11 FLUID FOCUS Howcan ScanningElectronMicroscopy(SEM) helpyou? Dynaleneutilizesastate-of-theartTescanVega 3VariablePressureScanningElectron Microscope(SEM)withsecondaryand Back-ScaterElectronDetectortoprovide comprehensivematerialanalysis.theenergy DispersiveX-RaySpectroscopy(EDS) detectoronoursem alowsustoprovide elementalcomposition,quantification, andsurfacemappingofyour material.useourservicestoget highresolutionpicturesto provideeasyvisualizationof yourmaterialorprocess. DO S & DON TS UseDeionizedwaterwhenblendingglycolstohelp maintainlowcorosionrates. CheckthepHandtheconcentrationoftheglycol regularly.thisisagreatindicatorofthequalityofthe glycolandshowsifsomethingisdegradingordilutingthe glycol. Flushthesystem beforereplacingwithnewglycolto keepthesystem freeofparticlesthatcouldcauseclogging. Usefiltrationwhenpossible.Addingfiltrationtoyour system wilhelpkeepitcleanandimproveheattransfer. Donotusegalvanizedmetals.Thesewilactualyhave highercorosionrateswhenusedwithcorosioninhibitor. Donotusealuminum unlessconsultingwithdynalene first.glycolwilworkwelwithaluminum,butspecific inhibitormustbeused. Donotstoreglycolinsunlight.Sunlightwilcauseglycol todegrade,increasingodoranddecreasingproductquality. Donotmixwithautomotiveantifreeze.Theinhibitors arediferentandcouldinteractwithdynaleneinhibitorsina negativeway.

12

13

14 Inadditiontousingdesiccatingequipment,improvedseal technologyaswelastrainingofthemaintenanceand operationspersonnelaboutthecorectpracticestousea heattransferfluidareessential.othermethodssuchas inexpensivegravityseparationandcomplexvacuum dehydrationarealsoutilizedtoremovemoisturefrom hydrocarbons[1]. Diferenttypesofmoistureadsorptionmediaareusedto removewaterfrom heattransferfluids.molecularsieves,a materialwithporeswithadiameterlessthan2nm (microporous)to50nm (macroporous)arecommonlyused desiccantstoadsorbmoisture[2,3].various aluminosilicate-basedmolecularsievesarecommonly usedincommercialdehydrationprocessesandare capableofadsorbingwaterattemperaturesashighas 90 C[4].Inaddition,saltssuchascalcium sulfateisused todehydratebothliquidsandgases. Inourpresentwork,themoisturesolubilitycharacteristicof aheattransferfluidwilbestudied.later,microporous molecularsieveswilbeusedtostudytheadsorptionrate ofthedesiccantintheheattransferfluidatvarious temperatures.theprimaryanalyticalinstrumentforwater determinationisakarlfischercoulometrictitrator. Inordertostudythemoisturesolubilityandthemoisture adsorptioncharacteristicsofthemolecularsievesat varioustemperatures,dynalenemvwasselectedasthe modelheattransferfluid.dynalenemvisanaromatic hydrocarbonbasedheattransferfluidwithaverylow operatingtemperaturerange,downto-112 o C(-170 o F).The

15 AdsorptioncharacteristicsofmolecularsievesinDynaleneMVheattransferfluid massedandinjectedintothekarlfischercoulometric titratorformoisturecontentanalysis. Sigma-Aldrich4Ametalaluminosilicate-basedmolecular sieveswereusedfortheadsorptionofwaterinsaturated solutionofdynalenemvatvarioustemperatures.the propertiesofthe4åmolecularsievesarelistedintable2. Figure2showstheexperimentalsetupusedtodetermine themoistureadsorptioncharacteristicsofthemolecular sievesindynalenemvatvarioustemperatures.thesetup consistsofthe PreppingChamber andthe Contact Chamber.80gramsofDynaleneMVheattransferfluid wassecuredinthepreppingchamberbyclosingvalve1 andvalve2.16gramsofmolecularsieve(whichis 20 wt.% ofthefluidtestsample)wasplacedinthecontact Chamber.Thefluidandthemolecularsievewere separatedbyvalve2,whichwasintheclosedposition beforethestartoftheexperiment.theexperimentalsetup wasplacedinthetesttemperaturefor1hour.the temperaturesusedforthistestingwere:-80 C,-58 C, obtainedinalow-temperaturevwrfreezer;-20 C, obtainedinaso-lowfdc-4000standardfreezer;0 C, obtainedinavwrstandardrefrigerator;and23 C, obtainedatroom temperature.later,valve2wasopened toinitiatecontactbetweenthemolecularsieveand DynaleneMVheattransferfluidinthe ContactChamber. Thealowedcontacttimeofthefluidwiththemolecular sievewas30minutes.thesetupwastiltedsothatfluid flowstothepreppingchamberandvalve2wasturnedto closedposition.the SeparatingMesh inthecontact Chamberpreventedthemolecularsievefrom enteringthe PreppingChamber.Thesetupwaswarmedtoroom temperatureusingaheatgunbeforethefluidsamplewas colectedforanalysis.valve1wasopenedandsyringes wereusedtocarefulywithdrawtheheattransferfluid sample.thesamplewasmassedandinjectedintothekarl Fischercoulometrictitratorformoisturecontentanalysis.

16 AdsorptioncharacteristicsofmolecularsievesinDynaleneMVheattransferfluid

17

18 ASTM corosiontestingforheattransferfluids

19 ASTM corosiontestingforheattransferfluids

20

21 Chloridetestingmethods measurestheelectricalpotentialinmilivolts(mv)untilthe concentrationofbothionsareatequilibrium.thiscreatesa breakdownvoltagewhereajumpinmvcanbeobserved, indicatingtheequivalencepoint. A0.01M AgNO 3 (aq)standardsolutionwasusedtotitrate thetestsamplesolution.10gramsofsamplewaterwas addedto80mlofa1:1:1(acetone:methanol:h2o)mole ratiomix.5mlofa0.002m NaCl(aq)solutionwasusedto spikeuptheunknown.theunknownsolutionwasvery basic;therefore,afewaliquotsofnitricacid(hno 3 (aq) wereaddedtolowerthephleveltonear3.aconductivity probewasplacedintotheunknownsolution,andthe electricalpotentialwasmeasuredovertheperiodof titration.thevolumeofstandard(v standard )addedtoreach theequivalencepointdependsonthechloridecontentof theunknown.higherchloridecontentrequireslonger titrationperiodsinordertoreachequilibrium.wecan calculatetheconcentrationoftheunknown,usingthe equationbelow: Striptestingwasabletomeasuresampleshavinga chloridecontentof 35ppm.S1-Wel,S3-DI,and S4-Bethlehem waterexhibitedverylowlevelsofchloride thatcouldnotbemeasuredusingthismethod.alentown tapwateryieldedthehighestlevelofchloride,havinga concentrationof81ppm.inalresults,stripmeasurements readhighervaluesthanmeasurementsrecordedby titrationandic. S3-DIwaterwastheonlysamplewithchloridecontenttoo low(na)forstripmethodtodetect.thelowestleveltheic wasabletomeasurewasins4-bethlehem tapwater, measuring10ppm.theicdetecteds5-alentowntohave thehighestconcentrationofchloride.measurementsforic wereallowerthanthevaluesfoundinstriptesting. Whichofthethreetestmethodsisthebest?Theansweris thereisnone.choosingamethoddependsonthe applicationofyouraqueousmixture.thereareprosand constoeachofthesetests. Chloridestripsarethemostuserfriendly,butat concentrationslowerthan35ppm thistypeoftestwilnot giveyouanaccuratemeasurement.asshownintable1, S1,S3,andS4,chloridelevelsaretoolowtodetect.DI samplesbarelyshowanytraceofchloridesbecausedi systemsremovechlorideionsfrom waterbyionexchange. Ifyouareextremelyconcernedabouthavingthelowest levelofchloride,diisthebestwatersource.assumingthat youhaveanideaofthechloridecontentofyourwater,use teststrips.inthissituationstriptestingisthebestchoice, becauseintheselowerlimitsthewaterissafetouseasa solvent.stripsarecompactandcanbeeasilystored,which isusefulwhentravelingorinthefieldawayfrom a laboratory.moreover,theyareeasilydisposable,and neitherapplicationnorcleanupconsumesmuchtime. Whenmeasurementsget 35ppm,cautionshouldbe takenwhenusingthismethod.stripsgiveyouan approximaterange;themeasurementcanbeseveralppm underorovertheactualvalue.thisisespecialyimportant

22 Chloridetestingmethods foraqueoushtfmixtureswithhigherpercentagesof watersuchasglycolfluids.theglycol:h2o ratiomixvaries indiferentapplications,butfordynaleneglycolproducts engineersrecommendthatthefinalmixturebe 25ppm chloridetomaintaintheefectivenessoftheinhibitors[4]. Ina50:50mixture,thechloridecontentisdilutedtohalf thatofthesourceofwater.under40ppm,thewateris safetouse,becauseinthis50:50mix,thechloridecontent inthefinalsolutionisaround20ppm.butforsolutionsthat haveahigherpercentageofwaterinthefinalvolume,the chloridecontentislessdilutedandcanreachunfavorable levels.undertheseconditions,stripsmaynotprovidean accurateenoughchlorideconcentration,andthewater shouldbesentoutforfurthertesting. Forotherapplicationsthatrequirehigherdegreesof accuracy,titrationandicarebeterchoices.when workingwithhtfmixtures,withlargervolumeofwater, knowingtheexactlevelofchlorideinthatfinalsolutionwil makeasignificantdiferenceinhowwelthefluidswil work.forexample,ifastriptestshowedachloridecontent of35ppm,a50:50mixtureissafetoworkwithasthefinal solutionwouldcontainhalfthechloridecontent.theexact chloridecontentinthiscaseisirelevant,becausethefinal solutionwouldnotbeabovethethresholdchloridelevelof 25ppm.Butforothermixtures,striptestingisnotsensitive enoughtodetectthemaximum alowablechlorideinthe fluid.takealookattable1,chloridelevelsfors5are lowerusingthetitrationandicmethod.anengineer wantingtodilutedynaleneglycolproducts,wouldnotuse Alentowntapwaterbecausethestriptestingmeasures81 ppm.formixturesofa50:50ratio,81ppm becomes40.5 ppm inthefinalsolution.thiswouldmakethefinalsolution welabovethe25ppm threshold.however,icdatashows adiferentpicture.ittelsusthatthechloridecontentfors5 isactualycloserto54ppm,whichisslightlyabove25ppm aftera50:50dilution. UnlikeIC,titrationshavealimit.Titrationisbestat measuringhigherchlorideconcentrations.inthis experimentthetestrangethresholdwas 35ppm.Results forsampleshavingaconcentrationlowerthan35ppm were notapplicable(valueswerenegativeintergers).best resultsareobtainedwhentitratingsolutionsthatinitialy startwithaconductivityof70mvorhigher.ifsamplesare

23

24 TemperaturerangereferencechartforDynaleneheattransferfluids Headquarters: 5250W.CoplayRoad,Whitehal,PA Phone: / Fax: Web: Midwestlocation: 648BennetRoad,ElkGroveVilage,IL Westlocation: 1701S5350W,SaltLakeCity,UT DynaleneisanISO-9001certifiedleadingmanufacturerandsupplierofheat transferfluids.forthepast20years,dynalene squalityproductshavebeen usedinavarietyofapplicationsbythousandsofcustomersworldwide.