Comparison of Two Different Cooling Methods for …

1 Corporation, NewCastle,PAAbstractThispaper wi ll co mparethetotal powerconsumptionoftw o differentmeansofheating/coolingsystems:a irandwater. Forasi ng le90mmextrude r,thetotal powerconsumption,outputra te,andthermal controlwill beusedtocomparethetwocoolingmeans. Fou r Different canbe addedorremovedfromth e extru de r idealforprocessesth at do notrequirehighenergyremov isless expensivefo r thehardware, easiertomaintain, ha slower operatingcos ts , andreq uires lessspaceco mparedtofluidcooli ng. Ai r co olingpr ovidesforslowerch g is bestsuitedforprocessesth at , th eequipmentis moreexpensive, requireshighermaintenanceto prevent fouling,andrequiresmorespaceanda waterpump. Thermal instabilitycanal sooc curifthecoolingwaterfl thermalgradientsproducedbywater coolingca n al socontributetoexcessivethermal str ainandstressintheextruder .EquipmentTheextruderusedforthisstudywas a 90mm( )x24:1 NRME xtruderwithfivete mper aturezonecontrollers.

2 It is eq uippedwitha 112kW(1 50Hp) ol edsyste mco nsisted of is se t of 3000 Wattheaters(6000 Watt s pe r zone). Coolingofeach zon e iscontrolledbya solenoidth at opensandcloses a va is pu lledfromthesystemthrougha he at exchangeranddiscarded. The solenoidsandheat exchangerarebothshowninFigure2. A continuouslyrunningwater pumpisshowninFigure3. Thispumpis a 1000 showsonezoneoftheair ofthefivezones containsa setof3000 Watt heaters(6000 Wattsperzo ne). Eac h heate r is ca st bloweris toth e activatedbythezoneco d at (265cfm).Eachzoneis isolated gure5 sh owsanoverviewofth e ai r cooledsystemwithallheaters, p coverhasbeenremovedinFigure5. Theheatedairexitsinanairgapjustunder thetopco vershownin Fi gure 6 is the711mm(28 ) Fl ex -li p Sheetdie andtheDyniscoSc re (. 100 ).TheScr eenChangerwasloadedwi thabreakerplate anda 20/40/60/2 0 sc reen melt probewasinsertedinthemeltstreambetweenth escreen lowshearbarriermixingscrew wasused foral l testing.

3 Itwasspecifically designed forpolypropylenewitha longfeed FlukeDataAcq uisitionSystemwasusedtoacquiredatafr willbereferr resinswereuse d forthisstudy. ExxonMobil LDPELD100BW, MFR NovachemicalsNovapolHD-2007-H HDPE, MFRof ExxonMobil PP9852EI, EastarEB062 PETG, IV of .75dl/gExperimentalProcedureEach ofthefour resinswasextrud edwithwatercooling andthen withair co olingfora to tal ofeightone-hou r , thebarrel andsc re w waspr e-heatedtwohours priortoea chonehourtes t, andthebar re l waspre-he at edforonehourbe ad y thermalcondi tionswerethen assumedto prevailthroughouteach hourlo ngte wererunwiththewate r-co oledtrialswereco mpletedtheextruderwasretrofittedforair - Cooling . The samecontrollersusedfo r wate r-coolingwereusedwithth e theheateramperageandvo ltagewere checke d onea , theextruder wasstart edan d settoa speedof75rpm. Thethermocoupletemperature s, th eamountofti methehe aters were on , motoramps, sc rewspeed,meltpro bete mper ature, andtheamou ntoftime th ebl owersran(air co oling)were te mperaturewasmeasuredeverytenminutes withanIRgunanda ha nd te s weremeasure d enextractedfromtheNetDAQandcompiledwith a sp readsheet pr wereon wasusedinconjunctionwith theheateramperageandvoltagetocalculateth eenergy(kilowatt -hours) consumedbyeachheaterandblo werduringthehour longte st.

4 Thesamewasdoneforthedrivemotorenergy . Theenergyaddedtothepolymerwas calculatedfromthedifferencebe tweenthepolymerproduc t melttemperaturean d th efeed tempe ResultsThewater-cooledsystemusedslightly more energyth antheair-cooledsystemforallfo waslit tl e differenc e be Themai n differencewas power usedbe tweenthecoolingsystems. Thewat ercooledused about22%moreenergycomparedto theair patternsareseen and10. LDPEte stshadsimilarvaluesbetweenthesystemswith thewaterusing7% d thelowesttotalpowerconsumptionswithco co oledused20% fferencewasthepowerus ageforheati energythantheair r thewate r-cooledsystemon2outofthe4 resins. PleaseseeFigure12. Temperaturecontrol va riedacc respecttoonlytheheating/coolingsystemLDP E hadth e hi ghestpowerconsumption forallresinsmainlybe ca useofpowernee dedinzone newas coolerduringth e wholetr ial e Figure 13. HDPE exhibiteda si milarpattern ofa co ole r zone 3 forbothsystemsaswell. Pleasese e Figure 14.

5 P P is confirmedinFigure15. PET wastheonlyre sinthatrequiredextensivecoolinginZone1du ringth e tr ia st emcouldn tmaintaintheactualtempera ture tothesetpoint . This isillustratedin di fferences be tweenthewaterandairsystemswasthecontinuo usrunningof thewater r al l wate r co ncewatercoolingis anabruptmean ofhe at extractionen ergy isremovedqu ickly andmanytimes re sultingin excessen ckinto thesystemtokee p thebarrelat tempera ture. Aircooling is moregradualanddoesn tov ercoola ba rr el se es s extensivecoolingis neededthenwatercoolingcanbeav oided. Airco olingshould bea suffi cientsystemformost prope rlyde signed woul d beusefulwhenmanydi ff erentpolymersaretobepr ocessed agiven screwdesign, somepolymers mayrequireex tensi vecoolingorheatingtopr oducethedesired productte s mayrequiretheadded heatcapacit y thewater provides . But it is versa tilityat thecostofth ermalst ab ilityand seenby thehighenergyconsu ac tualte mperaturevalueswerelo w duringthewholete qui redconstantpowerforboth diffe ren tproperlydesignedscr ewwouldalle viate th is wassp ecificallydesigned fo r e coolingwasre quiredtorunthePETresin stemco uldnotcontrolth is zone.

6 Howeverthewaterco ol ingcouldcontrolth is zone, butna turallyusedmoreenergy todo Thewaterlowere d thete mperatureofthefir st zonewhichloweredthesolids conveyingtoreduce ,outpu t ra te canalsobeaffectedbythecoolin gmea ns,especial lyasit affects e extruder barre l shoul d ba rr el celargethermalgradients in recommendedforan ex trude rdedicatedto a givenpr , thesc re w mustbeproperlyde signed tonotrequireexcessivecooling or he atingtomaintainproductte ngfinds uses whena givenex truderis used toprocess multiplepolymers an d ra coolingcanprovidegr ea t energytransfersothat pr oductte mperatureca n bemaintainedinspiteof a screwthatis notoptimizedfo r a gi venpolymer at a desired ,PolymerExtrusion, Han serPublishers,NY, ; W. mer,Ai r vs. WaterCooledSingle ScrewExtru ders, Wortberg; ,Novel BarrelHeatingwithNaturalGas, ANTEC2003 Figure2-WatercooledsystemHeatExchanger andSolenoidsFigure1-90mmx 24:1 NRME xtruderwithwatercooledsystemHeat ExchangerManifoldSolenoids`Figure3-Water cooledsystem-WaterPumpFi gure4-Ai r cooledsystem-SinglezoneFigure5-Air cooledsystem-OverviewWaterPumpFlowMeters AirCooledHeaterBlowerBaff leDieScreenChangerAir GapFigure6-Die, (KWh)Wat erAirComparisonofTotalKilowatt-hour sfor (KWh)TotalDriveHea.

7 SystemPowerConsumption(KWh)TotalDriv eHeat/CoolingCompari son ofTotalKi lowatt-hour sforProcessingLDPEC omparisonofTotalKilowatt-hoursforProcess ing erAirHeating/CoolingSystemPowerConsumpti on(KWh) (KWh)TotalDriveHeat/CoolingThroughputRat eforEachSystem16616910629216417197307050 100150200250300350 HDPELDPEPPPETR esinTypeThroughputRate(kg/hr)WaterkgAir kgFigure7-TotalEnergyConsumptionforthe8 testsFigure8-PowerConsumptionforHDPE forbothsystemsFigure9-PowerConsumptionfo rLDPE forbothsystemsFigure10 -PowerConsumptionforPPforbo thsystemsFigure11 -PowerConsumptionforPETforbothsystemsFi gu re12 -OutputRatesforall8 TestsTemperatureControlforLDPE ofbothsystemsversussetpoint1801902002102 20230240250260 Zone1 Zone2 Zone3 Zone4 Zone5 TemperatureCWaterAirSetpointTemperatureC ontrolforHDPE ofbothsystemsversussetpoint1801902002102 20230240250260 Zone1 Zone2 Zone3 Zone4 Zone5 TemperatureCWaterAirSetpointTemperatureC ontrolforPPofbothsystemsversussetpoi nt180190200210220230240250260 Zone1 Zone2 Zone3 Zone4 Zone5 TemperatureCWaterAirSetpointTemperature Control fo r PETof bothsystemsversussetpoint180190200210220 230240250260 Zone1 Zone 2 Zone3 Zone4 Zone5 TemperatureCWaterAirSetpointFigure13 -TemperatureControlofLDPE forbothcoolingsystemsFigure14 -TemperatureContro l ofHDPE forbothcoolingsystemsFigure15 -TemperatureControl

8 OfPPforbo thcoolingsystemsFigure16 -TemperatureControlofPETforbothcoolingsy stems