原版Electric arc furnace

Electricarcfurnace--PleaseClicktoReturntoFrontPageWesubscribetotheHONcodeprinciples.VerifyhereElectricarcfurnace电弧炉SteelmillwithtwoarcfurnacesEngineeringportalAnelectricarcfurnace(EAF)isafurnacethatheatschargedmaterialbymeansofanelectricarc.Arcfurnacesrangeinsizefromsmallunitsofapproximatelyonetoncapacity(usedinfoundriesforproducingcastironproducts)uptoabout400tonunitsusedforsecondarysteelmaking.Arcfurnacesusedinresearchlaboratoriesandbydentistsmayhaveacapacityofonlyafewdozengrams.Industrialelectricarcfurnacetemperaturescanbeupto1,800degreesCelsius,whilelaboratoryunitscanexceed3,000°C.Arcfurnacesdifferfrominductionfurnacesinthatthechargematerialisdirectlyexposedtoanelectricarc,andthecurrentinthefurnaceterminalspassesthroughthechargedmaterial.Contents1History2Construction3Operation4Advantagesofelectricarcfurnaceforsteelmaking5Environmentalissues6Otherelectricarcfurnaces7Plasmaarcfurnace8Vacuumarcremelting9Seealso10References11Furtherreading12ExternallinksHistoryInthe19thcentury,anumberofmenhademployedanelectricarctomeltiron.SirHumphryDavyconductedanexperimentaldemonstrationin1810;weldingwasinvestigatedbyPepysin1815;Pinchonattemptedtocreateanelectrothermicfurnacein1853;and,in1878–79,SirWilliamSiemenstookoutpatentsforelectricfurnacesofthearctype.ThefirstelectricarcfurnacesweredevelopedbyPaulHéroult,ofFrance,withacommercialplantestablishedintheUnitedStatesin1907.TheSandersonbrothersformedTheSandersonBrotherssteelCo.inSyracuse,NewYork,installingthefirstelectricarcfurnaceintheU.S.ThisfurnaceisnowondisplayatStationSquare,Pittsburgh,Pennsylvania.[1]Initiallyelectricsteelwasaspecialtyproductforsuchusesasmachinetoolsandspringsteel.Arcfurnaceswerealsousedtopreparecalciumcarbideforuseincarbidelamps.TheStessanoelectricfurnaceisanarctypefurnacethatusuallyrotatestomixthebath.TheGirodfurnaceissimilartotheHéroultfurnace.WhileEAFswerewidelyusedinWorldWarIIforproductionofalloysteels,itwasonlylaterthatelectricsteelmakingbegantoexpand.Thelowcapitalcostforamini-mill—aroundUS$140–200pertonofannualinstalledcapacity,comparedwithUS$1,000pertonofannualinstalledcapacityforanintegratedsteelmill—allowedmillstobequicklyestablishedinwar-ravagedEurope,andalsoallowedthemtosuccessfullycompetewiththebigUnitedStatessteelmakers,suchasBethlehemSteelandU.S.Steel,forlow-cost,carbonsteellongproducts(structuralsteel,rodandbar,wire,andfasteners)intheU.S.market.WhenNucor—nowoneofthelargeststeelproducersintheU.S.[2]—decidedtoenterthelongproductsmarketin1969,theychosetostartupamini-mill,withanEAFasitssteelmakingfurnace,soonfollowedbyothermanufacturers.WhilstNucorexpandedrapidlyintheEasternUS,thecompaniesthatfollowedthemintomini-milloperationsconcentratedonlocalmarketsforlongproducts,wheretheuseofanEAFallowedtheplantstovaryproductionaccordingtolocaldemand.Thispatternwasalsofollowedglobally,withEAFsteelproductionprimarilyusedforlongproducts,whileintegratedmills,usingblastfurnacesandbasicoxygenfurnaces,corneredthemarketsforflatproducts—sheetsteelandheaviersteelplate.In1987,Nucormadethedecisiontoexpandintotheflatproductsmarket,stillusingtheEAFproductionmethod.[3]ConstructionAschematiccross-sectionthroughanEAF.Threeelectrodes(black),moltenbath(red),tappingspoutatleft,refractorybrickmovableroof,brickshell,andarefractory-linedbowl-shapedhearth.Anelectricarcfurnaceusedforsteelmakingconsistsofarefractory-linedvessel,usuallywater-cooledinlargersizes,coveredwitharetractableroof,andthroughwhichoneormoregraphiteelectrodesenterthefurnace.Thefurnaceisprimarilysplitintothreesections:theshell,whichconsistsofthesidewallsandlowersteelbowl;thehearth,whichconsistsoftherefractorythatlinesthelowerbowl;theroof,whichmayberefractory-linedorwater-cooled,andcanbeshapedasasectionofasphere,orasafrustum(conicalsection).Theroofalsosupportstherefractorydeltainitscentre,throughwhichoneormoregraphiteelectrodesenter.Thehearthmaybehemisphericalinshape,orinaneccentricbottomtappingfurnace(seebelow),thehearthhastheshapeofahalvedegg.Inmodernmeltshops,thefurnaceisoftenraisedoffthegroundfloor,sothatladlesandslagpotscaneasilybemaneuveredundereitherendofthefurnace.Separatefromthefurnacestructureistheelectrodesupportandelectricalsystem,andthetiltingplatformonwhichthefurnacerests.Twoconfigurationsarepossible:theelectrodesupportsandtherooftiltwiththefurnace,orarefixedtotheraisedplatform.Atypicalalternatingcurrentfurnacehasthreeelectrodes.Electrodesareroundinsection,andtypicallyinsegmentswiththreadedcouplings,sothatastheelectrodeswear,newsegmentscanbeadded.Thearcformsbetweenthechargedmaterialandtheelectrode,thechargeisheatedbothbycurrentpassingthroughthechargeandbytheradiantenergyevolvedbythearc.Theelectrodesareautomaticallyraisedandloweredbyapositioningsystem,whichmayuseeitherelectricwinchhoistsorhydrauliccylinders.Theregulatingsystemmaintainsapproximatelyconstantcurrentandpowerinputduringthemeltingofthecharge,eventhoughscrapmaymoveundertheelectrodesasitmelts.Themastarmsholdingtheelectrodescarryheavybusbars,whichmaybehollowwater-cooledcopperpipescarryingcurrenttotheelectrodeholders.Mod