271paperTBM顶底复吹技术在梅山转rn炉的应用和维护英文

271paperTBM顶底复吹技术在梅山转rn炉的应用和维护英文ZHAOguoguangZUOkanglinGUOzhenheMeishanSteelPlantNanjingChinaABSTRACTInthispaper,thecomposingandcharacteristicsofTBMcombinedblowingtechnologyinMeishanSteelPlanthasbeenintroduced,higherdephosphorizationratio,lowercarbonoxygenproductlevelanddecreasedmetalchargeconsumptionhasbeenachievedviaappropriatesmeltingcrafts,summarizemaintenancetechniqueandinfluenceinconverterlineraboutTBMsystem.KEYWORDS:TBMcombinedblowing,dephosphorizationratio,carbonoxygenproduct,MaintenanceIntroductionMeiShansteelmakingplanthastwo150-tonscombinedblowingconverters,asaresultofthehighpercentphosphorusintheironoreoutputbyourownironmine,thepercentageof[P]inthemoltenironcangetto0.22-0.25%andallofthesteelstrandbemadetoproducesheetmetal.Ingeneraltherequiredpercentageis[P]<0.02%-0.025%andaslowaspossible.ThehighpercentageofphosphorusinthemoltenironseriouslyrestrictedthesmeltinganddevelopmentofthelowphosphorussteelanditalsotocausethehighconsumptionoflimeandmoreextrablowinginterminalpointintheprocessofsmeltingandthehighTFeintheslag,moltensteelperoxidationonterminalpointandinfluencedthefinalqualityoftheproducts.Inordertoimprovethesmeltingoperation,reducethecostofsmelting,lengthenthetimeofthegassupplybrickuseonthebottomblowingsystemandimprovethequalityofthemoltensteel.MeiShansteelmakingplanthascarriedontechnologicalreformtothetwo150-tonsconvertersintroducedTBM(ThyssenCombinedBlowingTechnology)thetechnologyofcombinedblowingtoimprovethesmeltingoperationon2002.TheTBMtechnologyismainlyrelyontherationalbottomblowingsystemcooperatewiththeappropriateoxygensupporting,slagmakingsystemtooptimizethefactorsondynamicsandthermodynamicsofthesmeltingprocesstoaccelerateandbalancedthereactingonthesteel-making,enablethesmeltingcoursetosteadilycontrolandreducethematerialandsuppliesconsumption.AfterTBMtechnologywasused,theterminalpointphosphorusofconverterhasgoteffectivecontrolwhilesmeltinglowphosphorussteelsuchasthepipelinesteel,girdersteelofautomobile,weldingsteel,etc.Italsoreducestheperoxidationproblemofextrablowingduetothehighpercentageofphosphorus.Thequalityofmoltensteelimprovedobviouslyandtheconsumptionofmaterialandsuppliessuchassteelmaterial,lime,oxygenarereducedenormouslyandthetechnicalindicationofsmeltprocessobviouslyimproved.1.CompositionofTBMsystem1.1BottomblowingsupplysystemTheformertechnologyuse8pieceofclusterbottomblowingventilativebrickandafterthereformthenumberofventilativebrickisalso8andassignedonthesameposition.Itscatteredevenlyontheperipheryofthenodalcircleonbottomwiththediameterof0.555D(Disthediameterofmoltenbath),assigntheformlikeFig.1.Fig.1:BottomblowingcomponentsanditssituationBottomblowingcomponentsusesinglebranchventilativebrickjustlikethefigure1.Thebottomblowinggassupplypipetobranch8piecesfromthemainpipe,themainpiperoutehasnitrogenandargonandcanswitchfromonetotheotheraccordingtotheneedandithasthenon-returnvalvepreventsthenitrogenorargontoflowingbackwards.Italsohastheflowwarningdevicepreventthelowgaspressuretocausetheventilativecomponentjam.Theeightbranchesallcanregulatealoneandeachflowiscontrolledbetween1.5m3/minto0.3m3/minandcanbeadjustaccordingtothesituationofrealtime.Atthesametimethissystemhasflowcompensationandifithasonepipelinejammedwecanchooseflowcompensationtodistributethesurplusflowtootherpipelinesaveragelytoensurethegassupportingallocation.Bottomblowingairsupplymodehave5typessolidifyinthefirstclassPCUandcanselect1typeamong5typesofmodesaccordingtothesmeltsteel.Furthermoreinthesecondclasshascontrastmodeformaboutgassupplyandsteelgradeanditcanselectcorrespondingbottomblowingmodeautomatic.Eachmodehas26controlpointsaccordingtothestepofsmelting;itisveryfavorabletosmeltingandcansetupthekindandtheflowofthegasaccordingtotheneedinthecourseofsmelting.1.2ReformofoxygenlancenozzleIntheformerweusefourholeoxygenlancenozzleandnowchangetosixholeoxygenlancenozzleafterintroducingTBMtechnology.Thepressureinfrontofregulatingvalveisabout1.5Mpaandtheoutletpressureis1.0MpaandtheMachnumberdesignfortheoxygenlancenozzleis2.25.Themainparameterofoxygenlancenozzleisinforms1:Tab.1:MaintechnicalparameterofoxygenlancenozzleMainparameterUnitBeforeTBMThenumberofholesPiece46Thediameteroflancethroatmm3030Thediameterofoutletmm4843.4Mpa0.901.20Machnumber2.02.25AngleoflancenozzleDegree1217.5AfteraperiodofusewefindthattheMachnumberoflancenozzleofferedbyforeigncompanyandthecenterlineincludedangleofnozzletoobigleadtothelancenozzleoverfiredandheavyerosiononsegmentofwallliningandmoltenbath.Wemakechangesonsomedataofnozzleaftercalculationandthesituationoferosionnotseriouslythanbefore.Seetheerosioncomparisonafterreformonnozzleinfigure2.Fig.2:Theerosioncomparisonbeforeandafterreformonnozzle1.3TBMcombinedblowingtechnologyTBMtechnologyimprovesthereactionspeedandbalancedbetweenmoltenbathandslagmainlythroughstrengtheningthedynamicsconditionofsmelting.Inthesmeltingprocessweadjusttheintensityofmixingofdifferentperiodthroughregulatingtheflowofbottomblowing.Atthesametimecooperatewiththeuseofthe6holelancenozzle,thepercentageofphosphorusinthemoltensteelavoidtraditionalphosphorusreversioninflectionpointinthemiddleperiod[2],thusmakethesmeltingreachhigherdephosphorizationrate,reducethesuppliesconsumptionatthesametimeandtheerosiontothefurnacewall.ComparingwiththesituationbeforereformtheTBMmainlyinfluencethecontrollingofthelanceandthematerialaddingmodeofthesmeltingoperating.AfterTBMtechnologyisused,feedinrawmaterial,oxygenlanceoperatingalltendtostability.Nowthefluctuatingrangeoflanceheightissmallandthetimeofconstantislong.Thephenomenaofslagbacktodryisobviouslyreducesanddurationisshortandnolongerappearthephenomenonofhanginglanceblowing.Itmaketheoperationofoxygenlancebecomemoreandmoresimple,Seethelanceheightdatacomparisoninfigure3andtable2.Fig.3CurvelineofoxygenlanceheightTab.2:SmeltingcourseandlanceheightdataItemLanceearlyheightSmeltingcourseDecarburizingpositionSlagsplashingtimeSplashsituationBacktodryofslagBefore240-270200-250180-2205-7minSeriousSeriousTBM180-220150-180160-1902-3minLessLessThecontrolofoxygenlanceissteadyinlocationaftertheintroductionofTBMtechnology,oxygenlanceisintervenedfew,thelanceheightchangevariationissmall,intheoperatingthenumberoftimesoflancetoreduceinthecourse,evenreachtheconstantlanceheightandmakelesssplash.Italsocaneasysplashtheslagontheearlystageoflanceheightandtheaveragesmeltinglocationoflancecanreduce40cmequally.Andtheoxygenlancefaultrateisreducedgreatlysoitreducingthephenomenonofsteelstickontheoxygenlance.Seeoxygenlancetroublecomparesintable3.Tab.3:oxygenlancetroublecomparisonItemErosionoflancebodyErosionoflancenozzleWarningstateofthetransmissiondeviceWarningstateoftensionBeforePronetosticksteelanderosionEasyerodeandleak1-2timesamonthOftengivethealarmOftengivethealarmTBMBasicallynotDifficulttoerodeandleakSeldomSeldomThewayinwhichthelimeaddingchangesandreducedthedegreeofdifficultytocooperatingwithoxygenlanceafterintroducingTBMtechnology,havingreducedthebatchwithmaterialandincreasedtheaddingamountofthefirstbatchofthelime.Seethelimeaddingcomparisonintable4.Tab.4:ThelimeaddingcomparisontheaddingamountofthefirstbatchofthelimeThebatchesneededTheaddingtimeThecoursecontrolsBefore5-6tons5-6times10-13minutesAddingthelimeformanybatches,difficulttocooperatewithoxygenlanceandslageasytosplashanddryTBM7-8tons3times6minutesFinishaddinglimebefore30%oxygenamount,smeltingsteadilyandeasytocooperatewithoxygenlanceAfterusingTBMtechnology,comparedwithbeforethemodeofthelimeaddingandthelanceheightcontroloptimizedandmakethesmeltingcoursecontrolbecomemoresteadilyandsimplifyandmaketheadvantageforrealizingthecomputermodelsteel-making.2ThemaineffectonsmeltingofuseTBMAfterusetheTBMtechnologythesmeltingoperationtoberelativelystableandtherateofdephosphorizationisimproved.Thecontrolontheleveloftheterminal[P]improves,andthedistributionofthephosphorus(LP=(P)/[P])fluctuatefrom60to160,upto98equally,andtheaveragedephosphorizationrateisupto92%.Thesuccessfulsmeltingrateofsteel,suchasthepipelinesteel,girdersteelofautomobile,weldingsteel,etc.obviouslyimproves.SeetheindexofTBMintable5.Tab.4:DephosphorizationindexofTBMP%ofmoltenironTerminalP%P2O5%inslagTheamounttocountTerminalcountednumberofP%<=0.01%0.2160.01043.295045TBMsystemthroughsetupbigbottomblowingflowinshorttimeafteroxygenblowingtopromotecarbontoreactwiththeoxygenandtheterminalaverageproductofcarbonandoxygento26(ppm*%).Theterminalproductofcarbonandoxygencanbestabilizedinthelevelof22(ppm*%)whilethebottomblowingingoodcondition.Seetherelationofterminalcarbonwiththeoxygendeterminationinfigure3:Fig.3:RelationofterminalcarbonwiththeoxygendeterminationUseofTBMcangetlowcarboncontentofmoltenbatheasilyinasituationthatthecontentoxygenofmoltensteelisnothighanditverysuitableforsmeltingthelowcarbonsteel.TFeisreducedintheslag,MgOisraised,andcanseethecomparesdataoftheslagintable5.Tab.5:ElementsofslagItemTFe%(average)MgO%(average)Before22.655.36TBM18.268.16Benefitfromthesteadyoperation,lessslagsplashandgoodterminalbalanceofsteelandslag,thespecificironandsteelconsumptionreduce10kgpertons.HeretaketheSPHCasanexampletoseetheindexandcomparisonintable6.Tab.6:SmeltIndexcontrastofSPHCItemTypicalvalueof[C]and[P]inonesampleMoltenbathterminal[C],[P]andslag(TFe)range%specificironandsteelconsumptionkg/tSmeltcycle(Minute)[C][P][C][P]TFeBefore0.180.0250.04~0.060.018~0.02218~25109641TBM0.300.0350.04~0.060.012~0.01816~21108538.23MaintenanceofTBMsystemThesituationofbottomblowingenormouslyinfluencetheeffectofTBMsincethetechnologyofslag-splashingforprotectionofconverterisapttocausethefurnacebottomtogouptoaffecttheventilationofbottomblowing,sothethicknessofcontrollingthefurnacebottomisthekeytosafeguardingTBM.Ingeneralcases,TBMbottomblowingventilativesituationcanbedividedintothreeobviousstates:(1)Whilepouringtheconverterthebottomblowingpositioncanbeseenatthebottomobviously,bottomblowinggascontinuousflowfromtheventilativebrickclusteredfromthebottom,becausethecoolingoftheblowinggasatthebottomactsonandformstheobviousblackcirclearoundtheventilativebrick,wecanseethefiercerisingofmoltensteelinthejointoftheventilativebrickandthemoltensteel,andtheterminalproductofcarbonoxygencanbeuptolevelof<20.(2)Becauseformthemushroomheadontheventilativebrickofbottomblowing,thegasflowfromitscatteredorcontinuousandthecoolingeffectonsomecertainwalloffurnacereduceasthegasflowoutscatteredinlargearea.Soitnotobvioustoseeblackcirclearoundtheventilativebrickandcan’tseethefiercerisingofmoltensteelinthejointoftheventilativebrickandthemoltensteel.Butcanseetheventilativemarkofloweringthetemperaturearoundtheventilativebrickaftersuspendingfurnacetimeslightlylongandtheterminalproductofcarbonandoxygenisabout24to30.(3)Bottomblowingventilativepipelinejammedorbottomblowinggasdisperseandoverflowfromthecupoutercoveroutsidethatformfromslag,can'tseethemoltensteelarisingfrombottomblowinggasatthesurfaceofthemoltensteelwhilepouringthefurnace.Andcan’tseetheventilativemarkofloweringthetemperaturearoundtheventilativebrickaftersuspendingfurnacetimeslightlylongbutcanseemarkofloweringthetemperaturearoundthegasoutletsandterminalproductofcarbonandoxygenisgreaterthan32.Ifitwantgetabettersmeltingresult,itneedtokeepbottomblowingstatebetweenstate(1)andstate(2).TheMEISHANsteelmakingplantexaminesthedailythicknessofthefurnacebottomandleveloftheproductofcarbonandoxygentocontrolthethicknessoffurnacebottomtomakestheproductofcarbonandoxygenbasicallyintherangeof20to30.Thestate(1)sincetheventilativecomponentandaroundareerodedseriouslybythemoltensteel,thefurnacebottomhasdangerofreducingandleaking,itneedtoincreasetheMgOcontentintheslag,lengtheningthetimeofslag-splashingandfeedinrawmaterialatthesametimetomakethefurnacebottomhaveupwardtrends.Thestate(3)becausethefurnacebottomgoupseriously,thoughitstillhavegasblowbuttheeffectofmixisveryfaintsoitcanthroughreducetheMgOcontentintheslag,shortenthetimeandfrequencyofslag-splashingtomakeareductionoftheslagonthefurnacebottomtoresumetheresultofbottomblowing.Thestate(2)needtojudgethedevelopmenttrendofproductofcarbonandoxygenandthicknessoffurnacebottomtotakethecorrespondingmeasureintime.Thenumberofmeltscanbemorethan10000andkeepingoodstatusofcombinedblowingbytheuseofTBM.SeetheventilativesituationphotoofbottomblowingofMEISHAN2#converterwhenitonit’s10032meltsinfigure4.Fig.4:PhotoofventilativesituationofbottomblowingofMEISHAN2#converterwhenitonit’s10032meltsTheerosionpositionofthefurnacewallafterTBMtechnologyputintopracticeisscarceintheearaxle,moltenbathandsegmentmainly.AftertakemodificationtotheincludedangleofthecentrelineandtheMachnumb