Innovation in Electric Arc Furnaces · Yuri N. Toulouevski Ilyaz Y. Zinurov Innovation in Electric Arc Furnaces Scientific Basis for Selection 123 Dr.YuriN.Toulouevski Dr.IlyazY.Zinurov 303-84OakridgeCourt B.KhmelnitskyStr.25,Apt.54 HollandLandingONL9N1R4 Chelyabinsk Canada 454047Russia [email protected] [email protected] ISBN978-3-642-03800-6 e-ISBN978-3-642-03802-0 DOI10.1007/978-3-642-03802-0 SpringerHeidelbergDordrechtLondonNewYork LibraryofCongressControlNumber:2009939072 ©Springer-VerlagBerlinHeidelberg2010 Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublication orpartsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9, 1965,initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violations areliabletoprosecutionundertheGermanCopyrightLaw. Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnot imply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotective lawsandregulationsandthereforefreeforgeneraluse. Coverdesign:WMXDesignGmbH,Heidelberg Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface Selectionofinnovationsforeachplantaswellasselectionofdirectionsoffurther developmentisoneofthecrucialproblemsbothforthedevelopersandforthepro- ducersofsteelinEAF.Ineffectiveselectionleadstoheavyfinanciallossesandwaste oftime.Inpractice,thishappensquitefrequently. Themainobjectiveofthisbookistohelpthereadersavoidmistakesinselecting innovations and facilitate successful implementation of the selected innovations. The entire content of the book is aimed at achieving this objective. This book containsthecriticalanalysisofthemainissuesrelatedtothemostwidespreadinno- vations in EAF. The simplified methods of calculations are used for quantitative assessment of innovations. These methods are explained by numerous examples. Considerable attention is given to the new directions of development which the authorsconsidertobethemostpromising. Intheprocessofwritingofthebook,itscontentwasdiscussedwithmanyspe- cialistsworkingatmetallurgicalplantsandforscientificresearchanddevelopment organizations. The authors express deep gratitude for their valuable observations andconsiderations. Anumberoftheimportantissuescoveredinthebookaredebatable.Theauthors would like to thank in advance those readers who will consider it possible to take thetimetosharetheirobservations.Theirinputwillbereallyappreciatedandtaken intoaccountinfurtherwork. OurheartfeltthanksgotoG.Toulouevskayaforherextensiveworkonprepara- tionofthemanuscriptforpublication. Ontario,Canada YuriN.Toulouevski v Contents 1 ModernSteelmakinginElectricArcFurnaces:History andProspectsforDevelopment . . . . . . . . . . . . . . . . . . . . 1 1.1 GeneralRequirementsforSteelmakingUnits . . . . . . . . . . 1 1.1.1 ProcessRequirements . . . . . . . . . . . . . . . . . . 1 1.1.2 EconomicRequirements . . . . . . . . . . . . . . . . 2 1.1.3 EnvironmentalandHealthandSafetyRequirements . . 5 1.2 High-PowerFurnaces:IssuesofPowerEngineering . . . . . . . 6 1.2.1 MaximumProductivityastheKeyEconomic RequirementtoEAF . . . . . . . . . . . . . . . . . . 6 1.2.2 IncreasingPowerofEAFTransformers . . . . . . . . 7 1.2.3 SpecificsofFurnaceElectricalCircuit . . . . . . . . . 8 1.2.4 OptimumElectricalModeoftheHeat . . . . . . . . . 11 1.2.5 DCFurnaces. . . . . . . . . . . . . . . . . . . . . . . 13 1.2.6 ProblemsofEnergySupply . . . . . . . . . . . . . . . 13 1.3 TheMostImportantEnergyandTechnologyInnovations . . . . 14 1.3.1 Intensive Use of Oxygen, Carbon, and ChemicalHeat. . . . . . . . . . . . . . . . . . . . . . 14 1.3.2 FoamedSlagMethod . . . . . . . . . . . . . . . . . . 15 1.3.3 FurnaceOperationwithHotHeel . . . . . . . . . . . . 16 1.3.4 UseofHotMetalandReducedIron . . . . . . . . . . 17 1.3.5 SingleScrapCharging . . . . . . . . . . . . . . . . . 17 1.3.6 Post-combustionofCOAbovetheBath . . . . . . . . 18 1.4 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.4.1 WorldSteelmakingandMini-mills . . . . . . . . . . . 20 1.4.2 TheFurnacesofaNewGeneration . . . . . . . . . . . 20 1.4.3 ConsteelProcess . . . . . . . . . . . . . . . . . . . . 22 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2 ElectricArcFurnaceasThermoenergeticalUnit . . . . . . . . . . 25 2.1 ThermalPerformanceofFurnace:TerminologyandDesignations 25 2.2 ExternalandInternalSourcesofThermalEnergy:UsefulHeat . 27 2.3 FactorsLimitingthePowerofExternalSources . . . . . . . . . 28 vii viii Contents 2.4 KeyRoleofHeatTransferProcesses. . . . . . . . . . . . . . . 29 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3 TheFundamentalLawsandCalculatingFormulaeofHeat TransferProcesses . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.1 ThreeWaysofHeatTransfer:GeneralConcepts . . . . . . . . 31 3.2 ConductionHeatTransfer . . . . . . . . . . . . . . . . . . . . 32 3.2.1 Fourier’s Law. Flat Uniform Wall. Electrical–ThermalAnalogy . . . . . . . . . . . . . . 32 3.2.2 CoefficientofThermalConductivity . . . . . . . . . . 35 3.2.3 Multi-layerFlatWall . . . . . . . . . . . . . . . . . . 38 3.2.4 ContactThermalResistance . . . . . . . . . . . . . . 39 3.2.5 UniformCylindricalWall . . . . . . . . . . . . . . . . 40 3.2.6 Multi-layerCylindricalWall . . . . . . . . . . . . . . 41 3.2.7 SimplifyingofFormulaeforCalculationof CylindricalWalls . . . . . . . . . . . . . . . . . . . . 42 3.2.8 Bodies of Complex Shape: Concept of NumericalMethodsofCalculatingStationary andNon-stationaryConductionHeatTransfer . . . . . 43 3.3 ConvectiveHeatExchange . . . . . . . . . . . . . . . . . . . . 47 3.3.1 Newton’sLaw:CoefficientofHeatTransferα . . . . . 47 3.3.2 TwoModesofFluidMotion . . . . . . . . . . . . . . 47 3.3.3 BoundaryLayer . . . . . . . . . . . . . . . . . . . . . 48 3.3.4 Free(Natural)Convection. . . . . . . . . . . . . . . . 49 3.3.5 ConvectiveHeatTransferatForcedMotion . . . . . . 50 3.3.6 Heat Transfer Between Two Fluid Flows Through Dividing Wall; Heat Transfer Coefficientk . . . . . . . . . . . . . . . . . . . . . . . 52 3.4 HeatRadiationandRadiantHeatExchange . . . . . . . . . . . 56 3.4.1 GeneralConcepts . . . . . . . . . . . . . . . . . . . . 56 3.4.2 Stefan–BoltzmannLaw;RadiationDensity; BodyEmissivity . . . . . . . . . . . . . . . . . . . . . 57 3.4.3 HeatRadiationofGases. . . . . . . . . . . . . . . . . 60 3.4.4 HeatExchangeBetweenParallelSurfacesin TransparentMedium:EffectofScreens . . . . . . . . 61 3.4.5 Heat Exchange Between the Body and Its Envelope:TransparentMedium . . . . . . . . . . . . . 62 3.4.6 HeatExchangeBetweentheEmittingGasand theEnvelope . . . . . . . . . . . . . . . . . . . . . . . 63 4 Energy(Heat)BalancesofFurnace . . . . . . . . . . . . . . . . . . 65 4.1 GeneralConcepts . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.2 HeatBalancesofDifferentZonesoftheFurnace . . . . . . . . 66 4.3 ExampleofHeatBalanceinModernFurnace . . . . . . . . . . 69 4.4 AnalysisofSeparateItemsofBalanceEquations . . . . . . . . 70 4.4.1 OutputItemsofBalance . . . . . . . . . . . . . . . . 70 Contents ix 4.4.2 InputItemsofBalance . . . . . . . . . . . . . . . . . 72 4.5 ChemicalEnergyDeterminationMethods . . . . . . . . . . . . 73 4.5.1 UtilizationofMaterialBalanceData . . . . . . . . . . 73 4.5.2 AbouttheSo-Called“EnergyEquivalent”ofOxygen . 74 4.5.3 CalculationofThermalEffectsofChemical ReactionsbyMethodofTotalEnthalpies . . . . . . . . 75 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 5 EnergyEfficiencyCriteriaofEAFs . . . . . . . . . . . . . . . . . . 81 5.1 PreliminaryConsiderations. . . . . . . . . . . . . . . . . . . . 81 5.2 CommonEnergyEfficiencyCoefficientofEAF andItsDeficiencies . . . . . . . . . . . . . . . . . . . . . . . . 83 5.3 Specific Coefficients η for Estimation of Energy EfficiencyofSeparateEnergySourcesandEAFasaWhole . . 84 5.4 DeterminingSpecificCoefficientsη . . . . . . . . . . . . . . . 88 5.4.1 ElectricalEnergyEfficiencyCoefficientη . . . . . . 88 EL 5.4.2 FuelEnergyEfficiencyCoefficientofOxy-gas Burnersη . . . . . . . . . . . . . . . . . . . . . . . 89 NG 5.4.3 EnergyEfficiencyCoefficientofCokeCharged AlongwithScrap . . . . . . . . . . . . . . . . . . . . 90 5.4.4 DeterminingtheSpecificCoefficientsηbythe MethodofInverseHeatBalances . . . . . . . . . . . . 91 5.5 TasksofPracticalUsesofSpecificCoefficientsη . . . . . . . . 91 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 6 PreheatingofScrapbyBurnersandOff-Gases . . . . . . . . . . . 93 6.1 ExpediencyofHeating . . . . . . . . . . . . . . . . . . . . . . 93 6.2 ConsumptionsofUsefulHeatforScrapHeating,Scrap Melting,andHeatingoftheMelt. . . . . . . . . . . . . . . . . 94 6.3 High-TemperatureHeatingofScrap . . . . . . . . . . . . . . . 95 6.3.1 CalculationofPotentialofElectricalEnergySavings . 95 6.3.2 SampleofRealization:ProcessBBC–Brusa . . . . . . 96 6.4 SpecificsofFurnaceScrapHamperingItsHeating . . . . . . . 97 6.5 ProcessesofHeating,LimitingFactors,HeatTransfer . . . . . 98 6.5.1 TwoBasicMethodsofHeating . . . . . . . . . . . . . 98 6.5.2 HeatingaScrapPileinaLarge-CapacityContainer . . 99 6.5.3 HeatingonConveyor . . . . . . . . . . . . . . . . . . 102 6.6 DevicesforHeatingofScrap:Examples . . . . . . . . . . . . . 105 6.6.1 HeatinginChargingBaskets . . . . . . . . . . . . . . 105 6.6.2 DCArcFurnaceDanarcPlus . . . . . . . . . . . . . . 108 6.6.3 ShaftFurnaces. . . . . . . . . . . . . . . . . . . . . . 110 6.6.4 Twin-ShellSteelmeltingUnits . . . . . . . . . . . . . 111 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 7 ReplacementofElectricArcswithBurners . . . . . . . . . . . . . 115 7.1 AttemptsforCompleteReplacement . . . . . . . . . . . . . . . 115 x Contents 7.2 PotentialitiesofExistingBurners:HeatTransfer, LimitingFactors . . . . . . . . . . . . . . . . . . . . . . . . . 117 7.3 High-PowerRotaryBurners(HPR-Burners) . . . . . . . . . . . 120 7.3.1 FundamentalFeatures . . . . . . . . . . . . . . . . . . 120 7.3.2 Two-StageHeatwithHPR-Burners . . . . . . . . . . . 120 7.4 IndustrialTrialsofHPR-Burners . . . . . . . . . . . . . . . . . 122 7.4.1 SlagDoorBurners:EffectivenessofFlame DirectionChanges. . . . . . . . . . . . . . . . . . . . 122 7.4.2 Two-StageProcesswithaDoorBurnerin6-tonFurnaces 124 7.4.3 Two-Stage Process with Roof Burners in 100-tonand200-tonEAFs . . . . . . . . . . . . . . . 127 7.5 OrielandSidewallHPR-Burners . . . . . . . . . . . . . . . . . 131 7.6 FuelArcFurnace(FAF) . . . . . . . . . . . . . . . . . . . . . 135 7.7 EconomyofReplacementofElectricalEnergywithFuel . . . . 137 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 8 BasicPhysical–ChemicalProcessesinLiquidBath:Process Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 8.1 InteractionofOxygenJetswiththeBath:GeneralConcepts . . 141 8.2 OxidationofCarbon . . . . . . . . . . . . . . . . . . . . . . . 142 8.3 MeltingofScrap . . . . . . . . . . . . . . . . . . . . . . . . . 144 8.4 HeatingoftheBath . . . . . . . . . . . . . . . . . . . . . . . . 146 9 BathStirringandSplashingDuringOxygenBlowing . . . . . . . . 149 9.1 StirringIntensity:MethodsandResultsofMeasurement . . . . 149 9.2 MechanismsofBathStirring . . . . . . . . . . . . . . . . . . . 150 9.2.1 StirringThroughCirculationandPulsation . . . . . . . 150 9.2.2 StirringbyOxygenJetsandCOBubbles . . . . . . . . 151 9.3 FactorsLimitingIntensityofBathOxygenBlowing inElectricArcFurnaces . . . . . . . . . . . . . . . . . . . . . 152 9.3.1 IronOxidation:EffectofStirring . . . . . . . . . . . . 152 9.3.2 BathSplashing . . . . . . . . . . . . . . . . . . . . . 154 9.4 OxygenJetsasaKeytoControllingProcessesintheBath . . . 157 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 10 JetStreams:FundamentalLawsandCalculationFormulae . . . . 159 10.1 JetMomentum . . . . . . . . . . . . . . . . . . . . . . . . . . 159 10.2 Flooded Free Turbulent Jet:Formation Mechanism andBasicPrinciples . . . . . . . . . . . . . . . . . . . . . . . 160 10.3 SubsonicJets:CylindricalandTaperedNozzles . . . . . . . . . 162 10.4 SupersonicJetsandNozzles:OperationModes . . . . . . . . . 165 10.5 SimplifiedFormulaeforCalculationsofHigh-Velocity OxygenJetsandSupersonicNozzles . . . . . . . . . . . . . . 167 10.5.1 ALimitingValueofJets’Velocity . . . . . . . . . . . 169 10.6 LongRangeofJets . . . . . . . . . . . . . . . . . . . . . . . . 170 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 Contents xi 11 Devices for Blowing of Oxygen and Carbon intotheBath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 11.1 BlowingbyConsumablePipesSubmergedintoMelt andbyMobileWater-CooledTuyeres . . . . . . . . . . . . . . 171 11.1.1 Manually Operated Blowing Through ConsumablePipes . . . . . . . . . . . . . . . . . . . . 172 11.1.2 BSEManipulator . . . . . . . . . . . . . . . . . . . . 172 11.1.3 MobileWater-CooledTuyeres . . . . . . . . . . . . . 174 11.2 JetModules:Design,OperatingModes,Reliability . . . . . . . 177 11.2.1 IncreaseinOxygenJetsLongRange:CoherentJets . . 178 11.2.2 EffectivenessofUseofOxygen,Carbon,and NaturalGasintheModules . . . . . . . . . . . . . . . 181 11.3 BlowingbyTuyeresInstalledintheBottomLining . . . . . . . 183 11.3.1 Converter-TypeNon-water-CooledTuyeres . . . . . . 183 11.3.2 TuyeresCooledbyEvaporationofAtomizedWater . . 184 11.3.3 Explosion-ProofHighlyDurableWater-Cooled TuyeresforDeepBlowing . . . . . . . . . . . . . . . 187 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 12 Water-CooledFurnaceElements . . . . . . . . . . . . . . . . . . . 193 12.1 PreliminaryConsiderations. . . . . . . . . . . . . . . . . . . . 193 12.2 ThermalPerformanceofElements:BasicLaws . . . . . . . . . 193 12.3 PrinciplesofCalculationandDesignofWater-CooledElements 197 12.3.1 DeterminingofHeatFluxRates . . . . . . . . . . . . 197 12.3.2 MinimumNecessaryWaterFlowRate . . . . . . . . . 199 12.3.3 CriticalZoneoftheElement . . . . . . . . . . . . . . 200 12.3.4 TemperatureofWater-CooledSurfaces . . . . . . . . . 200 12.3.5 TemperatureofExternalSurfaces . . . . . . . . . . . . 202 12.3.6 GeneralDiagramofElementCalculation . . . . . . . . 204 12.3.7 HydraulicResistanceofElements . . . . . . . . . . . 204 12.4 Examples of Calculation Analysis of Thermal PerformanceofElements . . . . . . . . . . . . . . . . . . . . . 207 12.4.1 MobileOxygenTuyere . . . . . . . . . . . . . . . . . 207 12.4.2 ElementswithPipesCastintoCopperBody andwithChannels . . . . . . . . . . . . . . . . . . . . 209 12.4.3 JetCoolingoftheElements . . . . . . . . . . . . . . . 212 12.4.4 OxygenTuyereforDeepBlowingoftheBath . . . . . 213 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 13 PrinciplesofAutomationofHeatControl . . . . . . . . . . . . . . 217 13.1 PreliminaryConsiderations. . . . . . . . . . . . . . . . . . . . 217 13.2 AutomatedManagementSystems . . . . . . . . . . . . . . . . 217 13.2.1 UseofAccumulatedInformation:StaticControl . . . . 217 13.2.2 MathematicalSimulationasMethodofControl . . . . 218 13.2.3 DynamicControl:UseofOn-lineData . . . . . . . . . 221 13.3 RationalDegreeofAutomation . . . . . . . . . . . . . . . . . 227 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228