汽轮机轴向位移异常的原因分析与消除

1、技术交流汽轮机轴向位移异常的原因分析与消除沈达(南通醋酸纤维有限公司,江苏南通226008)摘要叙述了抽汽背压式汽轮机因推力轴承部套的瓦枕球面体表面配合间隙调整的微小误差,导致轴向位移失常的原因,通过对推力轴承球面体径向配合重新调整,使轴向异常位移消除,机组运行正常。关键词汽轮机;轴向位移;球面体;推力轴承中图分类号TK267文献标识码B(0070021缺陷情况3.43/0.981/0.491994年投入运行。在运行中曾发现1、2号轴承振动偏大,停机检查发现,该轴承下瓦乌金有脱壳剥落现象。检修时,更换了新轴瓦,其中1号轴承为球面自位推力轴承,由径向轴承内瓦与球面瓦枕组合而成。当时,因球面座无库

2、存备品,仅更换了轴承内瓦。在调整新内瓦与旧瓦枕球面的配合时,将过盈调整到0.00±0.01mm的规定值,并检查轴向位移间隙为0.42mm,与标准值0.5mm基本相近。检修后开机试运行,轴向位移出现了反常现象:当转速升到500r/min时,轴向位移间隙由0.42mm降至0.33mm,以后轴向位移间隙随着转速的升高而不断下降,转速升到额定值3000r/min时,轴向位移仅0.07mm,即转子从静止到全速,轴向位移变化达0.35mm。同时,1号轴承的垂直和轴向振动均超过0.05mm,机组无法正常投运,当即决定机组提前进行大修。1捏手杆2螺母3滑阀4调整螺钉5罩帽6弹簧7喷油嘴臂8喷油嘴9汽

3、轮机转子图1轴向位移保护装置窗口A、B,再通过危急遮断油门、磁力断路油门前往自动主汽阀;另1路自窗口C,经节流阀D,再经喷油嘴臂中心孔,由喷油嘴喷出。正常工作时,弹簧6的紧力被压力油室I的油压对滑阀3的作用力所克服,油门处于图示状态。静止时,喷油嘴与转子挡油盘间的间隙为0.5mm,当转子轴向位移超过0.7mm,即喷嘴间隙增至1.2mm时,控制油压将下降至0.25MPa,滑阀在弹簧力的作用下上移,切断通往主汽阀操纵座的安全油,并令其泄去,使主汽阀迅速关闭,实现轴向位移的保护。按制造厂的设计,在正常情况下,轴向位移间隙S与轴向位移控制油压p的关系见表1。2缺陷原因分析2.1轴向位移保护装置构造与工

4、作原理该型机组的轴向位移保护装置系一套带碟阀的液压遮断装置(图1),安全油分为2路:1路先经壳体上的20030219收稿日期:()技术交流表1轴向位移间隙与控制油压关系项目控制油压p/MPa轴向位移间隙S/mm00.970.10.920.20.790.30.680.40.60.50.5150.60.4550.70.410.80.360.90.331.00.2951.10.271.20.25按规定,当S、p值均调整合格后,轴向位移油压p将于0.4MPa时报警。此时,相当于推力瓦磨损0.2mm;当推力瓦磨损量高达0.7mm,也即轴向位移间隙增大到1.2mm时,轴向位移油压将降到0.25MPa,主汽

5、阀将自动关闭。显然,当推力瓦并未磨损,而因其它原因导致推力轴承的转动部分不正常位移时,也会产生与上述同样的结果。2.2轴向位移保护动作试验根据缺陷的象征,对轴向位移与油压的关系进行了带负荷试验。先按常规将轴向位移油压调整到0.5MPa,将轴向位移保护投入,然后机组带负荷,向位移间隙S与油压p2表2负荷/kW0500100015002000(报警)250030003500(跳机)1;3球面瓦枕2个方面进行。(1)轴向位移间隙测量如图2所示,于推力盘端面置百分表A、内瓦端面置表B、球面瓦枕端面置表C。分别由向前和向后地推动转子,记录3个百分表/mm0.070.150.200.250.280.285

6、0.290.31轴向位移油压/MPa0.500.470.440.410.340.3150.280.245数据见表3。表3转子轴向位移间隙测量值项目百分表A(转子)B(轴承内瓦)C(球面瓦枕)mm差值0.360.150.01前推2.822.382.98后推2.462.232.97测量结果表明:球面瓦枕移动0.01mm;轴承内瓦移动0.15mm;推力瓦块间隙0.36-0.15=0.21mm。可见,推力间隙虽合格,但因轴承内瓦具有0.15mm的附加位移,使得转子轴向的绝对位移增大,此附加位移成为轴向位移异常的根源。(2)球面座径向配合间隙的测量检修标准规定,径向轴承内瓦与球面瓦枕之间的径向间隙应为0

7、.00±0.01mm,即配合应处于过盈与间隙之间。经反复测量核实,实际存在0.02mm间隙。再将内瓦与瓦枕两者的球面进行着色磨合检查,发现两者的接触面积不足80%。分析认为,球面径向间隙实测为0.02mm,与标准比较虽仅差0.01mm,处于测量允许误差范围之内,但球面座为直径d230mm的球状体,经计试验中,当机组负荷升到1500kW以上时,轴向位移保护报警,负荷升到3500kW时,轴向位移油压降到0.25MPa以下,导致自动主汽阀关闭而停机。2.3解体检查与测量停机后,在正常情况下盘车,轴向位移表的变化应极其微小,但这时却发现,随着转子的缓慢转动,轴向位移值从0.48mm到0.32

8、mm之间变动,表明推力轴承的定位存在缺陷。此外,由于推力轴承之径向轴承内瓦已更新,而其球面瓦枕为原件,即怀疑两者球面的配合存在问题。该机的推力轴承部套为当前国内小型供热汽轮机的传统型式,其结构如图2所示,主要由推力瓦块、径向轴承内瓦及球面瓦枕所组成。检查工作重点,从轴(下转第73页)()技术交流上述问题,曾对低压缸进行了加固,其方法是:用25mm厚的钢板,割成一定形状,沿低压外缸(低外)下缸进行焊接。同时低外上缸就位,并打好销子,在中分面上作好标记,按标记边焊接边测量法兰中分面的间隙和汽缸台板间隙,根据变形情况调整焊接的顺序,使变形量最小。低压缸加固后,若发生变形,会导致5、6号轴承洼窝变形,

9、应根据测量情况,对瓦枕间隙、轴封的通流间隙进行调整。北仑港电厂在采用此方法处理后,曾由于低外下缸焊接应力的释放引起局部变形,导致低压转子与汽封发生摩擦。准格尔电厂1、2号机的低外下缸已经焊有加强筋。方案2实施工作量和技术难度较大,实施不当会产生反作用。若能够保证安全和详细计算低压缸的受力情况,采取加固低压缸是一个较为根本的解决方法。方案3在达拉特电厂1号机的5号、6号瓦温差大问题的处理过程中,ALSTOM,将轴瓦底部的调整垫铁外侧()各去掉0.03mm和0.15mm,行状态下,处理后发生了盘车过载的情况,是由于去掉部分垫铁后,使轴承在盘车期间形成一个斜面,顶轴油从楔形间隙析出,使转子顶不起来,

10、盘车力矩较大所致。所以,对1号机轴瓦的紧力进行了调整,前后端使用不同的力矩,在紧固的过程中,监视轴瓦与轴颈的接触情况,使其不出现间隙。调整后运行中没有再出现5号、6号瓦温差大的问题。但是,用同样的方法,处理1号机4号瓦的温差时,由于制造厂的轴瓦和轴承座的间隙超差,轴瓦在轴承座内有一定的活动量。当轴瓦水平方向窜动时,受底部调整垫铁的影响,发生憋劲,使轴瓦和轴颈的局部接触更趋加剧,导致温差进一步加大。综上比较ALSTOM机组处理类似问题的各方案,方案3解决问题较彻底,解决问题的工期不长,。,国华准格尔电厂采用了方案3,将5号瓦和6号瓦的底部垫铁处于温度高的一侧分别去掉0.08mm和0.05mm,根

11、据倾斜方向调整轴承结合面的螺栓紧力。1号机经过处理,再次起动后,5号、6号的温差小于10以下,取得了良好的效果。(上接第71页)算,当径向存在0.02mm的间隙,所导致转子的单侧位移即会超过0.15mm。在球面体磨合状况不理想的情况下,其位移值可能会更大一些。因此,无论对大型机组采用径向推力联合轴承或小型机组采用球面自位推力轴承,轴承的球面体径向配合均不应存在间隙,而应采用微紧力配合方式,其紧力以(0.010.03)mm为宜。紧力过大也不适宜,因为过大的紧力会妨碍球面的自由转动,失去自定位功能,从而影响推力块的均匀受力。合重新调整,保持0.02mm的紧力,其余间隙均不变。检修后机组试运行,从升

12、速至带负荷,轴向位移及其控制油压的指示均正常。1号轴瓦的振动也小于0.03mm,机组一直运行正常。4结语无论是大型汽轮机还是小型汽轮机,其推力轴承球面体径向配合的调整关系重大,其微小失误即会导致机组不能投运。为此,检修中对球面自位推力轴承配合精度要求要慎重对待。3检修措施及检修后运行状况检修中,将1号轴承内瓦与球面瓦枕间的径向配()flowdownwardandsoon.EXPERAMENTALSTUDYONFLOWFIELDBEHAVIORCONCERNINGTHECROSSEDJETFLOWSOFMICROSWIRLINGPRIMARYAIRASWELLASUPPERANDLOWERSEC

13、ONDARYAIRZHAOKaietal(35)waterslurryburner,whichhasacoaxialringThroughtestcarriedoutonthecoldstatesimulationteststand,theinfluenceofsecondaryairfromrectangularjetorificeuponthedynamicbehavioroftheprimaryaircoaltypejetflowcomposedofastraightflow(outerring)andaswirlingflow(innerring)oftheprecomustionch

14、amber,hasbeenstudied.Testandanalysisshowthattheflowpatternofeveryjetflowinajetflowgrouphasverylargedifferencewiththatofasinglefreejetflowduetomutualmixingandaffectingeachotherofthesaidjetflows.STUDYONPRIMEVALTEANSFFERINGPHENOMENONINTHEFLUIDIZEDBEDTANGSongtaoetal(41)Basedonpyrolysisexperimentofproduc

15、tsinthefluidizedbed,apeimevalanalysisofdataconcerningpressure,temperature,andshareofproducedgasinthefluidizedbedhasbeencarriedoutrespectively,havingbroughttolighttheprimevalphenomenonamongthem,andaconceptofprimevaltransferringphenomenonhasbeenintroducedaftercarryingoutcomparisonandanalysisofthethree

16、saidparameters.PREDICTIVECONTROLOFWATERLEVELINTHEBOILERDRUMZHAOChangxiangetal(45)Basedonthedynamicbehaviorofwaterlevelintheboilerdrum,apredictivecontrolschemeofwaterlevelinthedrumhasbeenputforward.Simulationtestshowsthatthesaidschemetobemoreapproachingtheidealeffectivenessthantheconventionalthreeimp

17、ulsecontrolscheme,andactuationofthevalveisstable,beinghelpfultolongtermeffectivecontrol.SIMULATIONSTUDYONFURNACETEMPERATURECONTROLBASEDONFUZZYCONTROLLERINPOWERPLANTOFBURNINGBLASTFURNACEGASJIADexiangetal(49)Inthermalpowerplantofburningblastfurnacegas,theinfluenceofblastfurnaceproductionupontheoperati

18、onofboilerwascomparativelylarge,makingtheinsaidboilertobeveryunstable.ThecontrollingeffectivenessofPIDcontrollerscommonlyusedatpresentinsaidthermalpowerplantisntveryideal.Forthisreason,astudyonfurnacetemperaturecontrolbyusinghasbeencarriedout.Thesimulationtestshowsthatthecontrollingeffectivenessoffu

19、zzycontrollerisbetterthanthatofPIDcontroller.Atthesametime,theproblemsexistinginfuzzycontrollercontrolofboilersandpossiblesolutionsthereofhavealsobeeninvestigated.CALCULATIONANDANALYSISOFVIBRATIONCHARACTERFORGROUPSYSTEMOFAGTURBINEGENERATORYOUGuoyingetal(51)Theinherentvibrationcharacteranddynamicresp

20、onseoftheentirefoundationgroupsystem(unit+foundwforagasturbinegeneratersetinathermalpowerplanthavebeencalculatedandanal2ysedbyusingthefiniteelementmethod.Theresultsshowthatthedesifoundsasturbinegeneratorsetisresonable,satisfyingrequirementsofthedesignspecification.SIMULATIONANALYSISOFCONSIDERINGNUNI

21、FORMDISTRIBUTIONOFRADIA2TIVEHEATFLOWZHUZhiwuetal(53)Simulationanalysisofthevaporizingtubesofboilerhasbeencarriedoutonthebasisofaprocessingmethodwithconsideringnonuniformdistributionparametersofradiativeheatflow.Underconditionofthenonuniform3Ddistributionof,theradiativeheatflowtransferredtothesurface

22、ofwaterwalltubesisalsononuniform.Forthisreason,thewaterwallsurfacehasbeendividedintosmallsimulationzonesalongdirectionsofheightandwidthofrisertubes,andthevariationofthevaporizingprocesswithintherisertubesalongheightdirectionhasbeenanalysedbyusingtheabovementionedprocessingmethod.Theresultsobtainedar

23、emorereasonablecomparedwiththatobtainedfromthetraditionallumpedparametersmethodandtheuniformradiativeheatflowdistributionmethod.Byusingtheresultsobtainedfromthesaidprocessingmethod,occurrenceofabnormaltubeswithworsenedheattransferlocalityandbackwardflowcanbedetermined,havingimportantsignificancefora

24、nalysingsafeandeconomicoperationofboilers.CHARACTERISTICCALCULATIONANDANALYSISOFGASTURBINESDURINGTHETIMEOFBURNINGLOWCALORIFICVALUECOALGASBAIHuifengetal(58)Thethermodynamiccharacteristicsofgasturbinesduringthetimeofburninglowcalorificvaluecoalgashavebeenstudied,aquantitativecalculationofthethermodyna

25、miccharacteristicsforsinglecycleandcombinedcyclebeingcarriedoutbyusingcomercialsolftwareGTPROimportedfromabroad,andtheenfluenceofadjustingtheflowpassageareaofcompressorandofadjustingtheflowpassageareaofturbinebeinganalysed.Theresultsofstudyhaveapplicablevalueinengineering.DEVELDPMENTOFHEATEXCHANGERI

26、NHIGHTEMPERATUREAIRGASIFICATIONSYSTEMCAOXiaohuaetal(61)Thenecessityofdevelopinghightemperatureairgasificationsystemforbiomasshasbeenbrieflystated,theworkingprincipleandbehaviorofhightemperatureairgeneratorinthesaidsystembeingpresented,andtheoreticalanalysisofheattransfercoeficientregardingthehoneyco

27、mblikeceramicmatrixkeypartsofthesaidairgeneratorbeingcarriedout.Thestructureanddimensionsofthesaidheatexchangerhavebeendesigned,thecoldstateexperimentalstudyshowsthatthedesignedstructureanddimensionsofsaidheatexchangerhavesatisfiedtheoveralldesignrequirements.DIAGNOSTICANALYSISOFTWOCAUSESLEADINGTOBO

28、ILEROUTFIREANDCOUNTERMEASURESFORSOLUTIONTHEREOFXUDangqi(65)BoileroutfireeventsduetotwocompletelydifferentcausesoccurredonboilerNo.1ofDawukouPowerPlantandboilerNo.2ofHuanengBeijingPowerPlanthavebeenanalysed.Onthebasisofdiagnotictests,theirsolutionmethodsaresuggestedasfollows:(1)foroutfireduetoexcessi

29、veoxygen,thesecondaryairvelocityandoxygenquantitycanbelowered,andtheoperationmodeofshrunkenwaistairdistributionbeingadopted;(2)forout2fireduetoseriouslackofoxygen,thecoefficientofexcessairatoutletoftheburner,theratioofprimaryairandfuel,aswellastheairtemperatureatoutletofcoalpulverizercanbeenhanced.Afteradoptingabovementionedmeasures,similaroutfireeventshaventagainoccurredonthetwosaidboilers.STUDYONELIMINATINGFIRECARRYINGINPRIMARYAIRJETORIFICEBYADMIXINGEXHAUSTGASWENGShanyongetal(67)Inviewoftroublesomeproblemsinfluencinguponthesafet