采用高温空气燃烧技术的铝矾土煅烧窑的数值模拟

太原理工大学硕士学位论文采用高温空气燃烧技术的铝矾土煅烧窑的数值模拟姓名：闫申申请学位级别：硕士专业：材料加工工程指导教师：高峰20100401I(HTAC)90800100050%60%30%k-εPDFDONOX12II34NOX50100545090IIINUMERICALSIMULATIONOFKILNWITHHTACINCALCININGBAUXITEABSTRACTHightemperatureaircombustionHTACtechnologywasdevelopedsuccessfullytobeanewtechnologyintheninetiesinJapan,whichpossessesenergysavingandenvironmentprotection.Thetechnologyhasbroughtnewopportunitiesforincreasingfuelutilizationandreducingenvironmentpollutionforeverycountry.HTACisanewtypecombustiontechnology,whichtheairisheateduptomorethan8001000throughrecoveringthewasteheatofhightemperaturefluegasexhaustedfromfurnace.Thetemperatureofexhaustisalittlehigherthanitsdewpoint.Thehightemperatureairandgasareejectedintofurnacetoformstablediffusioncombustion.Thus,theutilizationofthermalfactorisincreased.Comparedwithtraditionalcombustion,thefuelwouldbesavedupto50%60%,theequipmentsizedecreasedabout30%.Inthearticle,athree-dimensionnumericalsimulationprocessinarestrictedspaceforstudyingkilnwithHTACincalciningbauxiteiscreatedbyaCFDsoftware.K-εturbulentmodel,PDFnon-premixedcombustionmodel,discretecoordinateradiationmodelareconsideredinthephysicalmodel.Firstly,temperaturefieldandconcentrationfieldwereanalyzedaboutkilnwithHTACIVandtraditionalkiln;besides,thefactors,suchasairinletpressure,flowrateoffuelgas,preheatedtemperatureofcombustionair,distancebetweenfuelgasjetandairjets,arestudiedontemperaturefieldinthefurnace,concentrationfield,andNOxemission.Theresultsshowedthat1Compareswiththetraditionaldown-draftkilnthenewkilnhasgoodpropertiessuchas:Goodtemperaturelevel,smalltemperaturedifference,fuelburningentirely,energysaving.2Throughanalyzingtheresultsofnumericalsimulationabouttemperaturefieldunderdifferentconditions,wecanknowthatthehightemperatureregionandthetemperaturedifferencereduces,thetemperatureuniformityincreaseswithairpressurereducing;asthefuelvelocityincreasing,themaximumtemperaturerises,thehightemperatureareaexpandsandthetemperaturedifferencereduces;withtheairpreheatedtemperature'sincreasing,thehightemperatureregionandthetemperaturedifferencereduces,temperatureuniformityenhancesobviously;withtheincreasingofdistancebetweenfuelgasjetandairjets,themaximumtemperatureandthetemperaturedifferencebothrise.3Throughanalyzingtheresultsofnumericalsimulationaboutconcentrationfieldunderdifferentconditionswecanseethatthemethanedensitydistributionandtheoxygendensitydistributioniseven,theoxygendensityreducesandtheCarbondioxidedensityincreaseswithairpressurereducing;withtheincreasingoffueljetvelocity,airpreheattemperatureandVdistancebetweenfuelgasjetandairjets,theoxygendensityreducesandcarbondioxidedensityishighinthelowoxygenconcentrationregion.4TheresultsofnumericalsimulationaboutNOXemissionsunderdifferentconditionsshowthattheNOXemissionsreduceswithairinletpressureincreasing.Whentheairinletpressureincreasefrom50into100,thenitrogenoxidedecrementisthemostfast.TheNOXconcentrationincreaseswiththeincreasingoffueljetvelocityandairpreheattemperature.5Bymeansofthehottestsinthetestfurnace,thefurnacetemperaturedistributionandfurnacetemperaturefluctuationareanalyzedindifferentexchangeperiod,andregenerativebodyareanalyzed.Whentheexchangeperiodis450second,thefurnacetemperaturefluctuationisthehighest.Whentheexchangeperiodis90second,thefurnacetemperaturefluctuationisthelowest.KWYWORDS:Bauxite,Hightemperatureaircombustion,Numericalsimulation,Temperaturefield,Componentfield11.11.1.1(P•Berthier)(Al2O3·3H2O)[1-7]Al2O348%Fe2O31.1.240550750160200701001902508013020303040[2]194510195530196560207019852101997250[2]20051-152%220%[2]1-1[3]Tab.1-1Bauxitereservesintheworld[3]74.029.686.057.022.877.020.08.025.019.07.625.07.73.0814.07.02.89.07.02.823.06.02.46.55.82.326.03.51.43.63.21.283.52.00.82.534.213.8640.4250.0100320.0200628()90.9%(41.6%17.1%16.7%15.5%)159.1%()[4]98%88%11%1%[4-6]1-231-2Tab.1-2Thecharacteristicsandchemicalcompositionofbauxiteinchina%Al203Si02Fe2O37017361762.3611.575.785.39623194065.439.025.725.25401366.488.206.948.11663204365.459.05.757.27377181265.4111.803.415.541306757.069.4512.336.04760154.315.7621.359.432066854.926.5819.358.3423022155.5415.369.333.6218041458.3912.668.954.6117011658.3611.304.575.16400456.798.0116.547.0921012057.529.5410.976.03240278612763.1111.105.715.691561854.835.9620.639255338713561.9910.407.735.961.1.31-31-3[7]Tab.1-3Theclassificationofbauxite[7]1-D-K2-D-P3-B-K4-D-I5--D-K-RG90%43%5%Al2O3γ-Al2O3[7][4,7](1)(2)(3)1780(4)(5)(6)ZrO2(7)(8)1.2[7-12]D-K1(4001200)54001200400450600700800950SiO2400600α-Al2O3·H2O()→α-Al2O3()+H2O↑(1-1)Al2O3·2SiO2·2H2O()→Al2O3·2SiO2()+H2O↑(1-2)3(Al2O3·2SiO2)()→3Al2O3·2SiO2()+4SiO2(SiO2)(1-3)2(120014001500)1200SiO23Al2O3+2SiO2→3Al2O3+2SiO2()(≥1200)(1-4)10%13001400Fe2O3TiO2Al2O3SiO2Fe2O3TiO23(14001500)14001500150010µm170060µm90µm120014001500100300µm14001500[11]D-K10%6SiO2Al2O3[11]Al2O365%70%Al2O3/SiO2Al2O3/SiO2(2.55)Al2O31500(10%20%30%)1400150014001500[9-12]71.31.3.1→→→→→→→→→→→→→→→→→→→→→→1.3.2[11]1“”6.48%1.456218230250kg3100013001650170018001900[16]4a)b)c)5510d)e)PLC[16]10m380m310001800[16]18%[13]1.49[14-18]1[18]4m32[18