燃煤锅炉的燃烧进程控制毕业设计外文翻译Word格式文档下载.docx

燃煤锅炉的燃烧进程控制毕业设计外文翻译Word格式文档下载.docx

《燃煤锅炉的燃烧进程控制毕业设计外文翻译Word格式文档下载.docx》由会员分享，可在线阅读，更多相关《燃煤锅炉的燃烧进程控制毕业设计外文翻译Word格式文档下载.docx（9页珍藏版）》请在冰豆网上搜索。

燃煤锅炉的燃烧进程控制毕业设计外文翻译@#@@#@ControllingtheFurnaceProcessinCoal-FiredBoilers@#@Theunstabletrendsthatexistinthemarketoffuelsuppliedtothermalpowerplantsandthesituationsinwhichtheparametersoftheiroperationneedtobechanged（orpreserved）,aswellasthetendencytowardtheeconomicalandenvironmentalrequirementsplacedonthembecomingmorestringent,arefactorsthatmaketheproblemofcontrollingthecombustionandheattransferprocessesinfurnacedevicesveryurgent.Thesolutiontothisproblemhastwoaspects.Thefirstinvolvesdevelopmentofacombustiontechnologyand,accordingly,thedesignofafurnacedevicewhennewinstallationsaredesigned.Thesecondinvolvesmodernizationofalreadyexistingequipment.Inbothcases,thetechnicalsolutionsbeingadoptedmustbeproperlysubstantiatedwiththeuseofbothexperimentalandcalculationstudies.@#@TheexperienceCentralBoiler-TurbineInstituteResearchandProductionAssociation（TsKTI）andZiOspecialistsgainedfromoperationofboilersandexperimentalinvestigationstheycarriedoutonmodelsallowedthemtoproposeseveralnewdesignsofmultifuelandmaneuverable—inotherwords,controllable—furnacedevicesthathadbeenputinoperationatpowerstationsforseveralyears.Alongwiththis,anapproximatezero-one-dimensional,zonewisecalculationmodelofthefurnaceprocessinboilershadbeendevelopedattheTsKTI,whichallowedTsKTIspecialiststocarryoutengineeringcalculationsofthemainparametersofthisprocessandcalculatestudiesoffurnacesemployingdifferenttechnologiesoffiringandcombustionmodes.@#@Naturally,furnaceprocessadjustmentmethodslikechangingtheairexcessfactor,stackgasrecirculationfraction,anddistributionoffuelandairamongthetiersofburners,aswellasotheroperationswrittenintheboileroperationalchart,areusedduringboileroperation.However,theeffecttheyhaveontheprocessislimitedinnature.Ontheotherhand,controlofthefurnaceprocessinaboilerimpliesthepossibilityofmakingsubstantialchangesintheconditionsunderwhichthecombustionandheattransferproceedinordertoconsiderablyexpandtherangeofloads,minimizeheatlosses,reducetheextenttowhichthefurnaceiscontaminatedwithslag,decreasetheemissionsofharmfulsubstances,andshifttoanotherfuel.Suchacontrolcanbeobtainedbymakinguseofthefollowingthreemainfactors:

@#@@#@（i）theflowsofoxidizerandgasesbeingsettomoveintheflameinadesiredaerodynamicmanner;@#@@#@（ii）themethodusedtosupplyfuelintothefurnaceandtheplaceatwhichitisadmittedthereto;@#@@#@（iii）thefinenesstowhichthefuelismilled.@#@Thelattercaseimpliesthataflame-bedmethodisusedalongwiththeflamemethodforcombustingfuel.Thebedcombustionmethodcanbeimplementedinthreedesignversions:

@#@mechanicalgrateswithadensebed,fluidized-bedfurnaces,andspouted-bedfurnaces.@#@Aswillbeshownbelow,thefirstfactorcanbemadetoworkbysettingupbulkyvorticestransferringlargevolumesofairandcombustionproductsacrossandalongthefurnacedevice.Iffuelisfiredinaflame,theoptimalmethodoffeedingittothefurnaceistoadmitittothezonesnearthecentersofcirculatingvortices,asituationespeciallytypicalofhighlyintensefurnacedevices.Thecombustionprocessinthesezonesfeaturesalowairexcessfactor（α<@#@1）andalonglocaltimeforwhichthecomponentsdwellinthem,factorsthathelpmakethecombustionprocessmorestableandreducetheemissionofnitrogenoxides.@#@Alsoimportantforthecontrolofafurnaceprocesswhensolidfuelisfiredisthefinenesstowhichitismilled;@#@ifwewishtominimizeincompletecombustion,thedegreetowhichfuelismilledshouldbeharmonizedwiththelocationatwhichthefuelisadmittedintothefurnaceandthemethodforsupplyingitthere,fortheoccurrenceofunburnedcarbonmaybeduenotonlytoincompletecombustionoflarge-sizefuelfractions,butalsoduetofineonesfailingtoignite（especiallywhenthecontentofvolatilesVdaf<@#@20%）.@#@Owingtothepossibilityofpictoriallydemonstratingthemotionofflows,furnaceaerodynamicsisattractingagreatdealofattentionofresearchersanddesignerswhodevelopandimprovefurnacedevices.Atthesametime,furnaceaerodynamicsliesattheheartofmixing（masstransfer）,aprocessthequantitativeparametersofwhichcanbeestimatedonlyindirectlyorbyspecialmeasurements.Thequalitywithwhichcomponentsaremixedinthefurnacechamberproperdependsonthenumber,layout,andmomentaofthejetsflowingoutfromindividualburnersornozzles,aswellasontheirinteractionwiththeflowoffluegases,withoneanother,orwiththewall.@#@Itwassuggestedthatthegas-jetthrowdistancebeusedasaparameterdeterminingthedegreetowhichfuelismixedwithairinthegasburnerchannel.Such