冶金工程专业外语下学期课本.docx
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冶金工程专业外语下学期课本.docx
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冶金工程专业外语下学期课本
冶金工程专业外语
课程教材
冶金科学与工程学院
Contents
Unit1Furnace
BeforeReading
1.Lookupthefollowingwordsinyourdictionary.
refractory,conversion,forced-motion,hydraulic
2.Readthepassageandunderlinethefollowinginformationinthetext:
(1)Bywhichprinciplearethefurnacesclassified?
(2)Forwhatareheatingfurnacesemployedtoheatmaterials?
(3)Whatarethemainprimarysourcesofenergy?
(4)Howcanelectricenergybeconvertedtoheat?
(5)Whatarethefundamentsofthemoderntheoryoffurnaces?
Text
ClassificationofFurnaces
(1)
1.TechnologicalandStructuralClassificationofFurnaces
Bytechnologicalprinciple,allmetallurgicalfurnacesareclassedintomeltingandheatingfurnaces.
MeltingfurnacesservetomakemetalsfromoresandremeltmetalsforobtainingthedesiredpropertiesAcharacteristicfeatureofmeltingfurnacesisthatthematerialsprocessedinthemchangetheirstateofaggregation.
Heatingfurnacesareemployedtoheatmaterialsforroasting(limestone,magnesite,re-fractories,etc)ordrying(foundrymoulds,ore,sand,etc),asalsoforincreasingtheplasticityofmetalsbeforeplasticworking.Manyheatingfurnacesareusedforheattreatmentofmetals,inwhichthestructureofmetalsundergoescertainchanges.Allheatingfurnacesarecharacterizedbythecommonfeaturethatthematerialsprocessedinthemremaininthesamestateofaggregation.
Furnacesineachofthesetwogroupsareclassifiedaccordingtotheparticularoperationstheyareintendedtoperform.Forinstancemeltingfurnacesareusedformeltingiron,steelcopper,etc.Heatingofmetalsbeforerollingorforgingorforheattreatmentofmetals.Thesegroupsoffurnaces,intendedforspecifictechnologicaloperations,arealsoclassifiedbystructuralfeatures,methodsofmetaltransportinginthefurnace,andtypeofproductbeingheated.Forinstance,heatingfurnacesforheatingofmetalbeforerollingaredividedintothefollowinggroups:
(a)soakingpits,continuousfurnaces,batch-typefurnaces,etc;(b)in-and-out,pusher-typerotary-hearthfurnaces(3);(c)furnacesforheatingingots,bloomstubes,barstrips(3),etc
Fuel-firedfurnacesareclassifiedbythetypeoffuelused,Forinstance,steelmakingopenhearthfurnacesmaybegas-firedorfueloil-fired.
Furnacesmayberegenerativeorrecuperativeaccordingtothemethodtheheatofwastegasesisutilized.
Electricfurnacesareclassedbythemethodofconversionofelectricenergyintoheat,arcfurnaces,resistancefurnacesandinductionfurnaces.
Modernfurnacesarecomplexthermalplantsusuallycomposedofthefurnaceproperandauxiliaryequipment,Thefurnacepropercommonlyhasthereactionchamber(furnacespace)andmeansforproducingthermalenergy,suchasburnersinflamefurnacesorelectrodesandresistorsinelectricfurnaces,Theauxiliaryequipmentcomprisesmeansforutilizationoftheheatofwastegases,ventilatorsandexhausters,stacks,variousvalves,gates,etc.
Thetechnologicalprocessforwhichafurnaceisintendedisperformedinthereactionchamber.Allotherelementsofafurnaceservetoensurethemosteffectiveconditionsforthemaintechnologicalprocess.
2.FurnaceClassificationbythePrincipleofHeatGeneration
Allfurnacesrelyonconversionofsomeorotherkindofenergyintoheat,Themainprimarysourcesofenergyare(a)chemicalenergyoffuel(infuel-firedfurnaces);(b)chemicalenergyofmoltenmetal;and(c)electricenergy.
Infuel-firedfurnaces,thechemicalenergyoffuelisconvertedintoheatthroughcombustion.Inferrousmetallurgy,thisgroupoffurnacesincludesflamefurnacesandshaftfurnaces.Inflame(reverberatory)furnaces,thematerialbeingprocessedisusuallyplacedonthefurnacehearthandoccupiesonlyasmallportionofthereactionchambervolume.Themainportionofthereactionchamberisfilledwithflamesandincandescentcombustionproductswhichtransfertheirheattothematerial(mainlybyradiation).Thesefurnacescanbefiredwithgaseous,liquidorsometimeswithdustysolidfuel.
Inshaftfurnaces,allthespaceisfilledwithloosechargematerialswhichincludelumpysolidfuel,Uponburning,lumpsoffuelformcombustionproductsandliberatethermalenergywhichistransferredtothechargematerialsbyradiation,convectionandconduction,Inshaftfurnaces,thespacesbetweenlumpsandtheareaforheattransferarepracticallyindefinite.
Withmoltenmetals,thechemicalenergyofmetalisconvertedintoheatthroughcombustionofthepresentinthem,Infurnacesofthistype,suchassteelmakingconverters,theprocessofheatgenerationtakesplacedirectlyinthebulkofmaterial(moltenmetal)andgoeswelltogetherwiththeadoptedtechnology.Theheatevolvedisevenlydistributedoverthewholemassofmoltenmetal.
Insometypesoffurnace,theevolutionofheatmaybedueto
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