煤粉燃烧过程中NOx排放的数值模拟

上海交通大学硕士学位论文煤粉燃烧过程中NOx排放的数值模拟姓名：谭松申请学位级别：硕士专业：热能工程指导教师：吴国江;罗永浩20050217INOxNOxNOxNOxNOxOFANOxNOxNOxNOxPDFNOxNOxIINOxNOxNOxNOxNOxINUMERICALSIMULATIONONNOxEMISSIONSINCOALCOMBUSTIONPROCESSABSTRACTPollutantsfromcoalcombustionareamajorenvironmentalproblemsincetheyproducelargeamountofdust,sulfurdioxideandnitrogenoxides.Theformationofnitrogenoxide(NOx)incombustionsystemisasignificantpollutantintheenvironment,andthecontrolofNOxemissionsisaworld-wideconcernastheutilizationoffossilfuelcontinuestoincrease.Alotofresearchesonthecontrolofnitrogenoxideshasbeendone,however,sofarmanyrealflamesstillcannotbedescribedandcalculatedpreciselyduetothecomplexinteractionbetweenreactionanddiffusionoccurringincoalcombustion.Soitisalwaysimportanttodevelopthetheoreticalandexperimentalstudiesforthecombustion.AdvancesinthescienceofNOxreactions,mathematicalmodeling,andincreasedperformanceofcomputersystemshavemadecomprehensivemodelingofNOxformationanddestructionavaluabletooltoprovideinsightsandunderstandingoftheNOxreactionprocessesincombustionsystem.ThistechnologyhasthepotentialtoenhancetheapplicationofvariouscombustiontechniquesusedtoreduceNOxemissionsfrompracticalcombustionsystem.ThepaperpresentsareviewIIofthecombustionsimulationmethodandintroducedthemechanismofNOxformationincoalcombustion.TwomainmethodonrestrainingtheformationofNOxaredescribedindetail:theairstagedcombustionandthefuelstagedcombustion.Someexperimentshavebeendoneonthe“multi-functionallow-NOxcombustiontestreactor”.Thepapercompletedthesimulationoftheflow,combustionandheattransferinpulverizedcoalfurnace.Acomprehensivereactionmodelforconvertingfuelnitrogentonitricoxideingasflamesisusedtomodelfuelnitrogenformation.TheNOxtransportequationsaresolvedbasedonagivenflowfieldandcombustionsolution.ItisthusimportantthatanaccuratecombustionsolutionbecomesaprerequisiteofNOxprediction.Thestatisticalprobabilitydensityfunction(PDF)areusedtoobtainthetime-meanreactionrates.Thepredictionsareobtainedforanoperating300MWfullscalefurnace.Thepredictedresultsshowthatthesimulationagreeswiththebasiccharacteristicsoftheflowfieldcombustionandspeciesconcentrationdistributionsintheboiler.KEYWORDS:Coal-firedboiler,Low-NOxemissions,Turbulent,Numericalsimulation,Experiment120050217VIIAm2ABETm2/kgBETEJ/molFChJ/KgK1/sIJ/m2slmLmpPaQm3/sQJ/sQnetarMJ/KgReSRSckg/sTKtsUm/sVIIIV0Vem2/s3hkm2/s2mKg/msrKg/m3fΓfS175[1]20032“”“”600080008000110003000“”250060~701500—1750SO2NOx67NOxNOxNOx1-1NOxNOx850~1150mg/Nm3600~1200mg/Nm31000~1500mg/Nm3600~1400mg/Nm32002130542003712[2]NOx,,,.,,.,NOxNOx330[3]Boyd[4]kå500MWHeinAIOLOS[5]PCGC[6][7]Lockwood[8]1;23454,NOxkkffffrpSSgraddivudiv++Γ=)()((21)21ΓfS5fpSfuvwPkfghf[9][10][11[12]frpSUdiv=)((22)()()fmmrpuieffeffiSSgradudivudiv++=23()phRheffSQgradTdivUhdiv+-⎟⎠⎞⎜⎝⎛=smr(24)hkTQRk()effkkdivUkdivgradkGmrres⎛⎞=+-⎜⎟⎝⎠25()()()reeeeree11CGCkgraddivUdivk-+Γ=262526kkΓkGlkCD/23=e()()effpffdivUfdivSmrs=+(27)22212()()/effgeffggfffdivUgdivgradgCCgkxyzmrmres⎡⎤⎛⎞∂∂∂⎛⎞⎛⎞=+++-⎢⎥⎜⎟⎜⎟⎜⎟∂∂∂⎝⎠⎝⎠⎢⎥⎝⎠⎣⎦(28)6ujuiukuieffeffeffiiijjkkipSgxxxxxxxmmmr⎛⎞∂⎛⎞⎛⎞∂∂∂∂∂∂=++-+⎜⎟⎜⎟⎜⎟⎜⎟∂∂∂∂∂∂∂⎝⎠⎝⎠⎝⎠29Gk2jiiktjijtlamtuuuGxxxkCmemmre⎡⎤⎛⎞∂∂∂=+⎢⎥⎜⎟⎜⎟∂∂∂⎢⎥⎝⎠⎣⎦=Γ=Γ+Γ1kf120.091.44=1.92;1.3;0.7;2.80;1.92ghggCCCCmeeesssss=======2SfwKpSfKeffmkefftmmm=+2/tCkmmre=m[5]17-XxppxpDpFguuFdtdu+-+-=rrr)()((210))(pDuuF-24Re182DppDCdFrm=(211)upumrprpdRe||Reppduurm-=DCReRe221aaaCD++=(212)321,,aaa[13]u19.2-18)(tuu′+.TTds()dsustuuTppp∫∞′+′′=02)((213)TTuuji′′LTekCTLL=(214)LCTuuji′′sute-kekTL15.0≈(215)[14]ekTL30.0≈(216)w-kkew=(214)H2O,COH2CH49(Kobayashi)()pRTEeAR/111-=(217)()pRTEeAR/222-=(218)21,RR()()()()∫∫⎟⎠⎞⎜⎝⎛+-+=--ttapwvdtdtRRRRmmftm002122110,0,exp1aa(219)()=tmvt=0,pm=21,aa=am1a[15]2a1NOxfoxifuelioxiiZZZZf,,,--=(220)10Ziioxfuel(220)ffusermttSSffvft++⎟⎟⎠⎞⎜⎜⎝⎛∇⋅∇=⋅∇+∂∂smrr)()((221)SmSuserffP(f)fP(f)f(f)()()10fPfdfff-=∫(222)()()()2112'2200ffPfdffffff⎡⎤=-=-⎡⎤⎣⎦⎣⎦∫∫(223)(2-22)()P(f)P(f)P(f)PDFPDFPDFJonesWhitelawRichardsonBeta[16]BetaPDF11BetaPDFf2f′∫------=dffffffp1111)1()1()(baba2-24⎥⎥⎦⎤⎢⎢⎣⎡-′-=1)1(2ffffa2-25⎥⎥⎦⎤⎢⎢⎣⎡-′--=1)1()1(2ffffb2-26ff’P(f)P(f)222()[]ppdTTCD75.0102/∞+=2-27()pRTEeCR/2-=2-28RDRDpddtdmooxpp+-=02p2-29oxpRRDRDMRTYddtdmoxwoxpp+-=00,2rp2-3012P1rq()GCaqssr∇-+-=ss312-31assGC()()ssCass-+=Γ31Gqr∇Γ-=G()GSTaaGG=+-∇Γ∇44s2-32sGS2-312-3244TaaGqrs-=∇-2-33rq∇-P1:()()044=+-⎟⎟⎠⎞⎜⎜⎝⎛++∇Γ•∇GaaETaGpppsp2-34pEpa∑=→=NnpnpnpnVpVTAE140limpse2-3513∑=→=NnpnpnVpVAa10lime2-36(2-35)(2-36)pnpnpnTA,,enVNnpnA42pnpndAp=2-37pndn11.3-15Γ()ppaas++=Γ312-38()()VAfpnNnpnpnVp∑=→--=1011limes2-392-39pnfn()GaaETaqppr++⎟⎟⎠⎞⎜⎜⎝⎛+-=∇-psp442-40Spalding,Patankar10310514(NOx)NONO2N2ONH3HCNNONO2NO95NOxN2NOx150010067NOxNOxZeldovich1946Zeldovich22OO⇔3-1NNONO+⇔+23-2ONOON+⇔+23-33-1(T1538)NONO153-23-3NO[NO](3-2)(3-3)NOx3122[]2[][]/(.)dNOkONmolcmsdt=3-4k1141.210exp(38000/)T×-NOxHNOOHN+⇔[phone]ZeldovichNOxNOx[17](3-2)(3-2)NOxZeldovichNOxNON294.5107J/molNNONO+⇔+2NOx15002000NOxNOx25%[18]NOxNOxNOx16NOxNONO(31)NOO(31)NONONOxNOxNOxO2N2NOx1971FenimoreNOxNOxCHiN2NOxNOxNOxNOxNOxNOxNOxHCNCNNHN[1,19]NHCNNCH+→+2(36)NHHCNNCH+→+22(37)NCNHNCH+→+222(38)NCNNC+→+2(39)17CNNC222→+(310)NOxCHCH2NOxNOxNOxN