英文原文Newenergy-savingmechanicalmixerandOverviewofadaptablediedesignforextrusionAbstractIntheworktherearedescribedtheresultsfromthelaboratoryresearchesofthebasiccharacteristics(performance)ofonenewtypeofenergy-savingmechanicalmixer,conditionallynamedEleron.Thesecharacteristics(performance)arecomparedwithrespectiveresultsoftheotherknownintheliteratureandsuccessfullyusedinpracticemixers.Themixerisdesignedformixingandaeratingliquidsystemsanditwillbeeffectiveformixinginthefermentreactorsforbiochemicalindustries,wheretheprocessesareenergyabsorbing.Keywords:Mixer；Air-saturation；Power-number；Heatandmass-transferduringmixing；Aeration-number1.IntroductionInimplementingalong-term,energy-savingprogramforindustry1,thedepartmentofHeatandMass-TransferTechnicsinTU-Sofia,undertheguidanceoftheauthor,hasconditionallycreatedforpatentanoriginalconstructionofenergy-savingmixer.Ithasauniversalfunctionformixingliquidsystemsinchemical,food,wine,tobacco,andbiochemicalindustries.Weexpectourmixertotakeitsplacewithdignityinfermentationtechnics,becauseofitseasymanufacture,goodresultsinair-saturationandlowenergyconsumption.TillnowitwastheinvestigatedlaboratoryversionofEleron-1mixer,whichisasmalltype,withD=(0.25/0.35)T.UniversalappearanceofmixerisshowninFig.1.Itconsistsofacentralrounddisk(1),whichiscarryingpap(2)andfourwings(3).Thewingsarecutthroughinthemiddle(aa)andinthebeginning,neartherounddisk(cc),andthereceivingpiecesarebendarch-shapedupanddownward,makingfourbladeswithradiusR=(0.05/0.07)D.TheirlengthisL=0.8pR,as(considered)fromlineofbend.Thebladesoneachfollowingwingareindifferentorderinbenddirection,andbecauseofthisinworkingconditionstherearecircumstancesforvortexes.Thisisveryimportantwhenthereismorethanonemixeronashaft(Figs.1and2).Whenmounting,weobservetheaxialflows,createdbycurvedblades,tomeeteachother(ifweaimairsaturation)ortopasseachother,whenweaimmixingwithoutaeration.Inthiswaywecreatemultitudeofsymmetricalcurrentlines(vortexes),whichspreadsymmetricallyvessel.2.ExperimentalForresearchingcharacteristics(performances)ofmixerEleron-1thereareusedtwoidenticallaboratoryreactorswithplanebottomandreleasers,respectivelywithvolumes6.5and24dm3.Reactorsdiametersare,respectively190and300mm,andmixersaremakeupwithD_0.35T.Aspatternsubstancesthereareusedwateranddiethyleneglycol,whichunder20ChavedynamicalviscosityandPas.ReactorsconfigurationisonFig.2andtheexperimenttalinstallation,whichisused,isonFig.3.Withthisinstallationsconfigurationweareresearchingthepowerconsumption,workingwithandwithoutaeration,heat-transferduringmixingwithEleron-1,thatiswhyreactorshaveheat-transferbogies-worm-pipes(serpentines)withrespectivetubediameterd1andwindupdiameterdS,whichareonFig.2.FormeasuringDO2(dissolvedoxygen)inliquidphaseduringaeration,installationalsohasabottlewithnitrogen,air-compressor,sensorforDO2andawritinginstrument,whichregisteronthetapetheoxygenabsorption(Fig.3).Fig.1.SchemeofmechanicalmixerEleron-1inappearancefromabove.2.1.PowercoefficientdeterminationForthismixerscharacteristicareusedtworeactorsandtwopatternsubstances,andtherotationfrequencyofmixersshaftischangingfrom100to1200min_1.Rotationfrequencyischosenandfixedandafterthatiscontrolledwithelectroniccyclometer.Eu-numberisdeterminedunderequationanditisreadnetpowerconsumptionP,forrespectiverotationfrequency.ThedependencyisinFig.4andiscomparedwiththedependencyofRushton-turbine.2.2.Aeration-numberdeterminationThisexponentisdefinedunderknownmethods,whichisadoptedformixingtechnics.Inourreactorwithvolume6.5dm3,withthehelpofair-distributedmechanism,theairisentrancedwithflowofqG_0.1to1.5V.TheresearchingresultsareonFig.5andarecomparedandheat-transfersurface(serpentine).Fig.2.ConfigurationoflaboratoryreactorswithmechanicalmixerFig.3.Schemeofexperimentalinstallations:1,thermostat；2,reactor；3,pressurevessel；4,heat-transfersurface(serpentine)2.3.Mass-transfercoefficientdeterminationduringmixingwithEleron-1Thereareusedtworeactorswithdifferentvolumes,whichhaveair-distributedmechanismsandsensorformeasuringandregisteringofCO2inwater.Weworkunder20C,andtheliquidphase,beforeeachattempt,isscavengedwithnitrogenuntilinitialoxygenconcentrationC0,whichischangingprogressivelyandiswritingonthetapetillestablishinganequilibrium(saturationconcentration).3TraditionalMixer3.1Differentwaystoclassifythemixers.3.1.1Accordingtothenumberofmixingspindles.Therearesingle-spindlemixersanddouble-spindleoreventriple-spindlemixers.3.1.2Accordingtotheirmixingspeed.Thereareslow-speedmixers(lessthan30rev/min),highspeedmixers(above35rev/min),andvariablespeedmixers.3.1.3Accordingtotheiroperationmode.Theycanbeclassifiedintobatchmixersandcontinuousmixers.3.1.4Accordingtotheaxispositionofthemixingspindlefromwhichthemixingarmsreceivetorqueandmotion.Theycanbeclassifiedintoverticalmixersandhorizontalmixers.Inthischapter,hemachineswillbediscussedintermsofthisclassification.Investigationsshowthathorizontalmixersarestillthedominantmixingequipmentintodaysmodernbakeryandsnackindustry,fortheyareofsimpleconstruction,simpleinoperation,andcheapertorun.TheyalsohavevariedcapacitiesandcanbeusedforawidevarietyofmixturesfromathinbatterforcookiedepositingtoextremelytoughdoughforChinesesnackcasing.3.2HORIZONTALMIXERSHorizontalmixersarecharacterizedbyhavingahorizontallylocatedmixingspindleonwhichthemixingarmsarefixedintothemixingbowl.Fig.2.1isatypicalfrontviewofthiskindofmixer.3.2.1ConstructionAtypicalhorizontalmixerconsistsofamixingbowl，oneortwomixingspindlesbywhichthemixingarm(s)isoraredriventhroughtransmissionmechanisms，andamainframemadeofeithercastironorunitaryconstructionofheavysteelplate，Oneortwomotorsaremountedbelowformixingandbowltiltingfunctionstogetherwithafaciacontrolandanelectricinterlocksystemtopreventaccesswhenthemachineisrunning.Therearetwotypesofweighingsystems:oneisseparatefromthemixer；theothercalculatestheweightchangeofthecompletemixerbeforeandaftertheadditionofaningredient,themixerbeinglocatedonasuitableweighingscaleorplatform.Inthiscasethemixerisoftenreferredtoasaw