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Lesson14Boilermountings,managementandmaintenanceBoilermountings(附件)Certainfittings(附件)arenecessaryonaboilertoensureitssafeoperation.Theyareusuallyreferredtoasboilermountings(锅炉附件）.Themountingsusuallyfoundonaboilerare:SafetyvalvesThesearemountedinpairs（induplex)toprotecttheboileragainst(from)overpressure（超压）.Oncethevalveliftingpressure(启阀压力）issetinthepresenceofaSurveyor(验船师)itislockedandcannotbechanged.Thevalveisarrangedtoopenautomaticallyatthepre-setblowoffpressure(启阀压力）.MainsteamstopvalveThisvalveisfittedinthemainsteamsupplylineandisusuallyofthenon-returntype（止回型）.AuxiliarysteamstopvalveThisisasmallervalvefittedintheauxiliarysteamsupplyline,andisusuallyofthenon-returntype.Feedcheckorcontrolvalve(给水单向阀或控制阀)Apairofvalvesarefitted:oneisthemainvalve,theothertheauxiliaryorstandby.Theyarenon-returnvalvesandmustgiveanindication（指示）oftheiropenandclosedposition.WaterlevelgaugeWaterlevelgaugesor‘gaugeglasses’arefittedinpairs,atoppositeendsoftheboiler,theconstructionofthelevelgaugedependsontheboilerpressure.Airreleasecock（放气阀）Thesearefittedintheheaders（联箱）,boilerdrum（锅筒）,etc.,toreleaseairwhenfillingtheboilerorinitiallyraisingsteam（升汽）.SamplingconnectionAwateroutletcockandcoolingarrangementisprovidedforthesamplingandanalysisoffeedwater.Aprovision（装置）mayalsobemadeforinjectingwatertreatmentchemicals.Blowdownvalve(下排污阀)Thisvalveenableswatertobeblowdownoremptied（放空）fromtheboiler.Itmaybeusedwhenpartially（部分）orcompletelyemptyingtheboiler.Scumvalve(上排污阀)Ashallowdish（浅盘）positionedatthenormalwaterlevelisconnectedtothescumvalve.Thisenablestheblowingdownorremovalofscum（浮渣）andimpurities（杂质）fromthewatersurface.Whistle（汽笛）stopvalveThisisasmallborenon-returnvalvewhichsuppliesthewhistlewithsteamstraightfromtheboilerdrum（锅筒）.Watertubeboiler,becauseoftheirsmallwatercontentinrelationtotheirsteamraisingcapacity,requirecertainadditionalmountings:Automaticfeedwaterregulator（自动给水调节器）Fittedinthefeedlinepriortothemaincheckvalve（主给水阀）,thisdeviceisessentialtoensurethecorrectwaterlevelintheboilerduringallloadconditions.Boilerswithahighevaporationratewilluseamultiple-elementfeedwatercontrolsystem.LowlevelalarmItisadevicetoprovideauditory（听觉）oflowwaterlevelconditions.SuperheatercirculatingvalvesActingalsoasairvents,thesefittingsensureaflowofsteamwheninitiallywarmingthroughandraisingsteamintheboiler.Sootblowers(吹灰器)Operatedbysteamorcompressedair,theyareacttoblowawaysoot（烟灰）andtheproductsofcombustion（燃烧产物）fromthetubesurfaces.Severalarefittedinstrategicplaces（关键位置）.Thesoot-blowerlance（喷头）isinserted,sootisblownandthelanceiswithdrawn（取出）.Generalmanagementprinciplesandoperatingproceduresarewellknownandmustalwaysbefollowedtoavoidboilermishaps(意外事故、损坏).Inparticular:Withmanysmallpackageboilers(小型锅炉）,theautomaticcontrolsequence（自动控制时序）usuallyensuresthattheboilerfireisinitiallyignited（点火）fromadieseloilsupply,andchangedovertotheusualsourcewhenignitioniscompleted.Withgoodmanagement,tofacilitatesubsequentstartingfromcold,thefuelsystemoflargeboilerswillhavebeenflushedthroughwithdieseloilwhentheboilerwasonlightdutyimmediatelypriortobeingsecured（停炉）.Whenburningsuchdieselfuelitisessentialforsafetythatonlythecorrect(small)burnertip(油头)shouldbeused.Itshouldbekeptinmind（牢记）thatiffiredoesnotlight,immediatelyshutofffuelandventfurnace.Completeignitionoffuelinthefurnaceisessential.Theburnerflame,thesmokeindicator(烟气指示器)andthefunnel（烟囱）shouldbefrequentlyobserved.Withsatisfactorycombustion,theflameshouldappearincandescent(极亮)withanorangeshade(色度)attheflametip,andafaintbrownish（淡褐色）haze(烟雾、薄雾)shouldshowatthefunnel.Ifonfirstignitiontheflameisuncertain,badlyshapedandseparatedfromtheprimaryswirler(旋流配风器),momentary（瞬时）openingorclosingofairregister(调风门)[airregulator]maycorrect.ThepHvalueoftheboilerfeedwatershouldbekeptbetween8and9andtheboilerdensity（浓度）lessthan300ppm.But,ifwatersamplesshowaheavyconcentration（浓度）ofsuspendedmater（悬浮物）,shortblow-downs（下排污）of20secondsduration（持续的时间）shouldbegivenuntilthesludgecontentisseenreduced.Theboilershouldbeblowndownwhentheoilburnerisoperating,thewaterlevelloweredandthenrestoredtoprovethefunctioningofthelowwatercut-out（低水位切断）andtheoilburnerstart-up（燃烧器起动）equipment.Theboilerscumvalveshouldalsobeoperatedatthistimetokeepthewaterlevelclearfromfloatingscum（浮渣）.Fuelburnercomponents（燃烧器部件）andigniterelectrodes（点火电极）shouldbecleanedweeklyandthefurnaceexaminedtoensurethattherearenoexcesscarbondeposits（积炭）.Tubesintheexhaustgassectionoftheboilershouldbebrushedthroughataboutsix-monthlyintervals,andthoseintheoilburningsectionperiodicallyexaminedandcleanedasnecessarywithawirebristlebrush（钢丝刷）.Withcorrectfeedwatertreatment,blowdownproceduresandsludgecontentsinwatersamplesatastablelevel,itshouldnotbenecessarytowashoutthewatersideoftheboilermorethanonceeverythreeorfourmonths.Boilerfiresmaybeoutforlongperiodswhenashipisatseaandtheboilersteamingmaintainedbyheatinputfromwasteheatrecoveryplant（废热回收装置）.Thisoperationisfreefromhazard(危险),butfeedwaterandboilerwatertreatmentmustbemaintainedtopreventinternaldeterioration（腐蚀）orscaleformation.Waterlevelcontrollersmustbekeptop