热能与动力工程专业英语翻译CH02教案

1、Chapter2Boiler第二章锅炉29-9Airheater空预器Anchor支座，固定Anhydrousammonia无水氨Anthracite无烟煤Atomized雾化Austenitic奥氏体钢Auxialiary辅助机械Axis轴Bagasse甘蔗渣Baretube光管Bark树皮Beam梁，横梁Bituminouscoal烟煤Blade叶片Blast鼓风Blowdown排污Boiler锅炉Bulk大块的Burnerzone燃烧器区域Butane烷Calcination煨烧Capacity出力Carbonsteel碳钢Cerium制iChromium铭Circulatingflui

2、dizedbedCFB循环流化床锅炉Coalchar煤焦Cogenerator热点联产机组Combustion燃烧Commissioning试运行Compressor压缩机、压气机Condenser凝汽器Containment反应堆安全壳Convection对流Coolant制冷剂Coordinated坐标，定位Corten低合金耐腐蚀钢Counterflow逆流（换热器）Creepstrength蠕变强度Criterion标准Criticalpressure临界压力Culm煤屑Cyclonefurnace旋风炉Debris残骸、有机残留物Decane癸烷Decay分解Deposited沉积，

3、沉淀的Deterioration恶化Dieseloil柴油Differential差动，微分Distillate偏出物Distortion变形Divisionwall分隔墙，双面水冷壁Drainage疏水Drum汽包Dwelltime保留时间Economizer省煤器Embrittlement脆性，脆化Equalization均衡，平衡Erosive侵蚀的，腐蚀的Ethane乙烷Evaluate评估，评价Evaporate蒸发Excessair过量空气Extendedsurface扩展受热面Fatigue疲劳Feedwater给谁Ferrite铁素体Fin鳍片，肋片Flange法兰Fluega

4、s烟气Fouling沾污Furnace炉膛Generator发电机Geological地质的Girth环形Govern控制、调节Gravity重力Header联箱，集箱Helical螺旋状的Helium氮Heterogeneous不均匀的Hopper斗，料斗Husk壳，外壳Hydraulic水力的，液压的Ignite点火Impurity杂质Inert惰性Inferior低级的，劣质的Ingredients成分Ingress进口，入口In-line顺列Inorganic无机的Ion离子Jurisdiction权限Lignite褐煤Lime石灰Limestone石灰石Lowalloy低合金钢Low

5、-volatile低挥发分的Margin裕量，安全系数Matrix矩阵Membrane膜Methane甲烷Mill磨煤机Molecule分子Molten熔化Nitricoxide氮氧化物Nonpressure非承压的Nontoxic无毒的Organisms有机体Oxidation氧化Peat泥煤Pendantssuperheatplaten悬吊式屏式过热器Pentane戊烷Petrochemical石油化工制品Petroleum石油制品Plasmaspraycoating等离子喷涂Platen屏Polymer爽合物Pores气孔，小孔Porosity多空的Potassium钾Prandtlnu

6、mbers普朗特数Prefabricated预制的Premiumfuel优质燃料Pressureloss压力损失Primaryair一次风Propane丙烷Proximateanalysis工业分析Pulp纸浆Pyrites黄铁矿Radius半径，范围Rareearthelement稀土元素Recuperator间壁式换热器Regenerator回热器，蓄热器Regulate控制，调节Repercussions反应Reservoirs储气罐Residualefueloil渣油Resonant共振Retract缩回Reynoldsnumber雷诺数Rigid刚性的，紧密地Rollers辑子Sca

7、le水垢,Seal密封Sedimentary沉积Serpentinetube蛇形管Shale页岩Silica二氧化硅Silt淤泥Single-phase单相Skincasing外护板Slag结渣Slurry水煤浆Sodium钠Solvents溶剂Sootblower吹灰器Sourgas含硫气体Specification规格Stableignition稳定着火Stantonnumber斯坦顿数Saturated饱和的Straw稻草Steamlineblowing蒸汽管路吹灰Steams茎,杆Stresscorrosion应力腐蚀Structuralformula结构式Stud双头螺栓Subbit

8、uminous贫煤，次烟煤Suction真空，负压Sulphur硫Superheater过热器Swamp沼泽Sweetgas无硫气Switchgear配电装置，开关装置Temperature-entropy温燧图Tenacious黏的Thermodynamics热力学Tubebundles管束Tubular管状的Turbine汽轮机Velocity速度Verticalspidlemill中速磨,立轴磨Vessel容器Viscosity黏度Volumetricexpansion体膨胀Vulnerable易损的，薄弱的Wear磨损Welded焊接Wingwall屏式凝渣管Yttrim&LA

9、bbreviationsAFBC常压流化床燃烧AFCO燃料自动切断AFWC给水自动切断ASME美国机械工程师协会ATM标准大气压BFP锅炉给水泵BUT按钮BWC锅炉水浓度BYP旁路CFBB循环流化床锅炉MCR最大连续蒸发量DAS数据采集系统DEH数字电液系统DNB偏离核态沸腾FDF送风机FGD烟气脱硫FSSS炉虺安全检测保护系统HRB回热锅炉IDF引风机IGCC整体煤气化联合循环LMTD对数平均温差MFT主燃料切断MUF锅炉补给水NWL正常水位OFA火上风，燃尽风PFBC增压流化床燃烧SSC刮板除渣机TGA热重分析仪UBC未燃烧WFGD湿法烟气脱硫24IntroductionBoilersus

10、eheattoconvertwaterintosteamforavarietyofapplications.Primaryamongtheseareelectricpowergenerationandindustrialprocessheating.Steamhasbecomeakeyresourcebecauseofitswideavailability,advantageouspropertiesandnontoxicnature.Thesteamflowratesandoperatingconditionscanvarydramatically;from10(X)1b/h(0.1kg/s

11、)inoneprocessusetomorethan10millionIb/h(1260kg/s)inlargeelectricpowerplant;fromabout14.7psi(1bar)and212°Finsomeheatingapplicationstomorethan4500psi(3lObar)and1100°F(593)inadvancedcyclepowerplant.1.1 能介SSC锅炉利用热量使水转变成蒸汽以进行各种利用。其中主要是发电和工业供热。由于蒸汽具有有利的参数和无毒特性，因此蒸汽作为一种关键的工质(资源)被广泛地应用。蒸汽流量和运行参数的变

12、化很大：从某一过程里1000磅/小时(O.126kg/S)到大型电厂超过10X106磅/小时(1260kg/s),压力从一些加热应用的力.7磅/ii?(I.O135bar)212F(100)到先进循环电厂的4500磅/id(310bar)HOOF(593C)。Modemboilerscanbeclassifiedbyvariouscriteria.Theseincludeenduse,firingmethod,operatingpressure,fuelandcirculationmethod.现代锅炉可根据不同的标准分类。这些包括最终用途、燃烧方式、运行压力、燃料和循环方式。Utilityb

13、oilersareusedprimarilytogenerateelectricityinlargecentralpowerstations.Theyaredesignedtooptimizeoverallthermodynamicefficiencyatthehighestpossibleavailability.Akeycharacteristicofnewerunitsistheuseofareheatersectiontoincreaseoverallcycleefficiency.大型中心电站的电站锅炉主要用来发电。它们经过优化设计，可达到最高的热效率。新机组的关键特性是利用再热器提

14、高整个循环效率。Avarietyofadditionalsystemsalsoproducesteamforpowerandprocessapplications.Thesesystemsusuallytakeadvantageoflowcostorfreefuels,acombinationofpowercyclesandprocess,andrecoveryofwasteheatinordertoreduceoverallcosts,examplesoftheseinclude:各种附加的系统也产生蒸汽用于发电及其他过程应用。这些系统常常利用廉价或免费燃料，联合动力循环和过程，以及余热回收

15、，以减少总费用。这些例子包括：Gasturbinecombinedcycle(CC)useadvancedgasturbineswithheatrecoverysteamgeneratoraspartofabasecycletousewasteheatrecoveryandincreasethermalefficiency.燃气轮机联合循环(CC)：先进的燃气轮机，将余热锅炉作为基本循环的一部分，以利用余热并提高热效率。integratedGasificationCombinedCycle(IGCC)addsacoalgasifiertotheCCtoreducefuelcostandmini

16、mizeairborneemissions.整体煤气化联合循环(IGCC)：在CC基础上增加煤气化炉，以降低燃料费用并将污染排放降到最低。PressurizedFluidized-bedCombustion(PFBC)includeshigherpressurecombustionwithgascleaningandexpansionofthecombustionproductsthroughagasturbine.增压循环流化床燃烧(PFBC)：在更高压力下燃烧，包括燃气净化，以及燃烧产物膨胀并通过燃气轮机做功.Blastfurnacehoodheatrecoverygeneratesste

17、amusingthewasteheatfromablastfurnace.高炉排烟热量回收：利用高炉余热产生蒸汽。Solarsteamgeneratorusesconcentratorstocollectandconcentratesolarradiationandgeneratesteam.太阳能蒸汽发生器：利用集热器收集太阳辐射热产生蒸汽。1.2 DevelopmentofUtilityBoilerThemodem660MWcoal-firedboilerhassome6000tonsofpressurepartswhichinclude500kmoftubing,3.5kmofinteg

18、ralpipingand30,000tubebuttwelds.Itistheculmination教材25页ofsomefiftyyearsdevelopmentandwhilethebasicconceptofpulverizedfuelfiringintoafurnacelinedwithevaporatortubes,withthecombustiongasesthenpassingoverconvectionsuperheaterandheatrecoverysurface,hasremainedunchanged,theadvancementofsteamconditions,in

19、creasesinunitsizeandthepropertiesofthefuelfiredhaverequiredmajorchangesinmaterialsemployed,fabricationtechniquesandoperatingprocedures.1.3 电站锅炉的发展现代660MW燃煤锅炉有大约6000吨的压力部件，其中包括500米的受热面管材，3.5米连接管，和3(XXX)个管接头焊口。这是经过大约50年发展的成果，并形成了至今未变的基本概念，即燥粉在布置有蒸发管束的炉膛内燃烧，然后烟气通过对流过热器和热回收表面。蒸汽参数的提高，机组容量的增大及燃料燃烧特性改进都要求

20、在材料、制造技术和运行程序上相应发展。IntheyearsimmediatelyfollowingthesecondWorldWar,iswascustomarytoinstallinapowerstation,agreaternumberofboilersthanturbines,theboilersfeedingarangetowhichtheturbineswereconnected.Thisarrangementreflectedtheinferioravailabilityofboilerscomparedwithturbinesbutincreaseinboileravailabi

21、lityinthelate1940sledtotheacceptanceofunitizedboilersandturbines.Thechangetounitizedboilerandturbineallowedreheattobecomepracticaland,withtheavailabilityofhightemperaturesteels,therefollowedacontinuousadvanceinsteamingconditionstothecurrentstandardcycleof2400Ibf/in2(165.5bar),568withreheatto568C.Tot

22、akefulladvantageofthemoreadvancedsteamconditionsandtoobtaintheeconomiesofsize,thenextfifteenyearsalsosawatwenty-foldincreaseinunitsize.二战后的一些年里，在电厂安装锅炉的数量多于汽轮机是很常见的，锅炉提供蒸汽到母管然后到汽机。这种布置反应了锅炉的可用性低于汽轮机。四十年代后期，随着锅炉可用性的提高，锅炉和汽机开始可以相互配套使用°这一变化使再热变得可行，而且随着高温钢材可用性的提高，蒸汽参数不断变化，达到了当前的24001bf7in2(165.5bar

23、),568和568c再热的标准循环。为充分利用更高的蒸汽参数和获得更大的经济性，在接下来的15年，机组容量又增加了20倍。Autilitynormallyprocuresplantfromspecialistmanufactureswhohaveresponsibilityfordesign,manufacture,erectionandcommissioning.Whilethemanufacturescarryoutdevelopmentofmanufacturingprocessandcontinuouslyupdatetheirdesignmethods,andchangeinoper

24、ationconditionsandsizenecessarilyresultsinanewplantbeingofaprototypenature.Whilesomenewfeaturescanbetestedinadvanceofconstructiontheonlyrealtestofanewboilerdesignisinoperationandwithitsassociatedturbineandgenerator.Thecommercialsuccessofanewdesignisprovedoverthewholeprojectedlifeofpowerstationanduti

25、lity,therefore,hastobalancetheimmediateeconomicadvantagesofanewdesignintermsofimprovedefficiency,reducedcapitalcosts,etc.againsttheriskofpooravailability,needformajormodifications,etc.,whichmightresultfromanewdevelopment.Autilitynormallypurchasesplantagainstgeneratingneedsandtherepercussionsofpoorin

26、itialavailabilityarenotonlybeingunabletomeetloaddemandbutalsohavingtousecostlyplanttomakeuptheshortfall.Thisperiodofmajoradvanceinsteamcycleandunitsizethereforerequiredquiteexceptionalinteractionwithmanufacturersindesignandfabricationareaanddevelopmentofoperationandmaintenancetechniquestoensurethatt

27、heeconomicgainsdidnotproveillusory.电站设备一般向负责设计、制造、建设和调试的专业厂商购得。同时生产厂商实施生产过程的发展，不断修正设计方法，改变必要的运行参数和容量，从而形成新电厂的原型。虽然一些新的特性可以在安装前进行测试，但一个新设计锅炉的真正测试是和汽轮发电机组配套运行后进行的。一个新的设计获得商业成功需要通过电站在整个设计寿命中的使用来证明。因此，需要平衡考虑由效率提高、投资成本减少等带来的直接经济效益，与新设计机组可能产生的可靠性低和需要大的改进等风险。公用事业公司般依靠发电需求购买设备，并且最初可用性较低的影响不仅不能满足负荷需求，还需要使用品贵

28、设备以弥补不足。因此，在对蒸汽循环及机组容量进行较大改进的时期，必须和厂商在设计、制造领域，以及运行、维护技术领域密切合作，以保证经济利益的可靠。1.4 FuelandcombustionThefuelsusedinmostboilersarecoal,naturalgasandoil.However,duringthepastfewdecades,nuclearenergyhasalsobeguntoplayamajorroleinatleasttheelectricpowergenerationarea.Also,anincreasingvarietyofbiomassmaterialsa

29、ndprocessbyproductshavebecomeheatsourcesforsteamgeneration.Theseincludepeat,woodandwoodwasters,straw,coffeeground,comhusks,coalminewastes(culm)煤屑,wasteheatfromsteelmaking教材26页furnacesandevensolarenergy.2. 3燃料及燃烧大部分锅炉以煤、天然气和石油作为燃料。然而，在过去的儿十年里，至少在发电领域核能开始扮演一个主要角色。同样，不断增加的各种生物质和工业副产品也成为生产蒸汽的热源。这些包括泥煤、木

30、材及木材废弃物、麦秆、咖啡渣、玉米秆、煤矿废弃物(煤屑)、炼钢炉废热甚至太阳能。ThedominantfuelinmodemU.S.centralstationsiscoal,eitherbituminous,sub-bituminousorlignite.Whilenaturalgasorfueloilmaybethefuelofchoiceforselectedfuturefossilfuelpowerplants,coalexpectedtocontinueitsdominantroleinsupplyingenergytonew,basepowerutilitypowerstation

31、boilers.现代美国中心电站以煤作为主要燃料，使用烟煤、次烟煤或褐煤。虽然天然气和燃油也许是未来化有燃料电厂的燃料选择，但对于带基木负荷的新电站，燥仍将是主要的锅炉燃料。231CoalclassificationAcoalclassificationsystemisneededbecausecoalisaheterogeneoussubstancewithawiderangeofcompositionandproperties.ThepropertiesofatypicalChinacoalareshowedintable2-1.Coalsaretypicallycalssifiedbyr

32、ank.Thisindicatestheprogressivealterationinthecoalificationprocessfromlignitetosubitiminous,bituminousandanthracitecoals.Therankindicatesacoal'sgeologicalhistoryandcharacteristics.表21(27页)3. 3.1煤的分类由于煤是一种不均匀的物质，且其组成和特性变动很大，所以建立煤的分类系统是很必要的。中国煤的性质如表2-1所示。以煤阶进行燥的分类是典型的做法。这表现为煤化程度的大小：从褐煤到贫燥、烟煤以及无烟煤。

33、煤阶表明了煤的地质历史和主要特性。ThesystemusedintheU.S.forclassifyingcoalbyrankwasestablishedbytheAmericanSocietyforTestingandMaterials(ASTM).ASTMclassificationisasystemwhichusesthevolatilematterandfixedcarbon(FC)resultsfromtheproximateanalysisandtheheatingvalueofthecoalasrankingcriteria.Thissystemaidsinidentifying

34、commercialusesofcoalsandprovidesbasicinformationregardingcombustioncharacteristics.现在美国应用的煤分类标准是由美国材料试验学会(ASTM)建立的。其分类是通过煤的I：业分析所确定的挥发分和固定碳的含量以及煤的发热量作为分类标准。这套系统目的在于确定媒的商业使用价值，并提供关于煤燃烧特性的基本信息。4. 3.2CombustionsystemsThecombustionoffossilfuelswithinaboilerforsteamraisingpurposeshasbeenpractisedformanyy

35、ears.However,withinthepasttwodecadescombustiontechniqueshavebeenconsiderablyrefinedinordertoreduceatmosphericemissionsandpollutiontopracticableminimum.2.3.2燃烧系统锅炉内化石燃料燃烧以产生蒸汽的技术已成熟多年。然而，在过去的二十多年中，为了将大气排放和污染降到可行的最低程度，燃烧技术得到了很大程度的提高。OilcombustionsystemsOilisburnedinallutilityboiler,incoalboilertoignit

36、ethecoalburners,towarmuptheboilerandraisepressurebeforecoalisadmitted,andinoilfiredboilersasthemainload教材27页fuel.Ingeneral,theoilisresidualFuelOilof3500sec.to6500sec.viscosity.Inordertobumeffectivelythisoilmustbeheatedto120-130anddividedoratomizedintoverysmalldroplets.油燃烧系统所有的电站锅炉都燃用油,在燃煤锅炉中点燃煤粉,在媒进

37、入炉膛之前加热炉膛并升压,而在燃油锅炉中则作为主要负荷燃料。一般地，燃油都是玷度在3500sec到6500sec的残渣燃料油。为了有效的燃烧，这些油必须被加热到120130并被良好地分散或雾化成很小的微滴。Theuseofthisoil,cheaperthannormaldistillate(diesel/gasoiletc.)causesproblems,amongstthem,acidsmutsanddustemissions.Thesmutproblemiscausedbythesulfurcontentoftheoil,whichmaybeupto3%.Intheearly1960st

38、heutilityundertookanintensivedevelopmentprogramonoilburnerdesign,whichwasaimedatremovingtheproblemsofoilfiredemissions.Thisresultedinanoilburner,“theStandardBurner“whichreducedemissionsofcarbonatverylowexcessairlevels.Considerableworkwasalsodoneinordertoensurethatburnerinaboilerreceivedthesameamount

39、ofair,andthecurrentoperatinglevelforexcessairinanoilfiredunitis2%.燃用渣油，要比一般的储分油(柴油，汽油等)便宜，但又带来一些问题：酸性污染物和粉尘的排放。酸性污染问题是由石油中的硫产生的，硫分的含量有时可高达3%。在20世纪60年代早期，人们对油燃烧器设计进行了深入研究和开发，目的在于解决燃油的排放问题。由此诞生了一种油燃烧器“标准燃烧器”，它可以在非常低的过量空气系数下减少碳排放。为保证锅炉中每个燃烧器获得同样多的空气也做了大量的工作。目前油燃烧过量空气系数运行水平为2%oCoalcombustionsystemsCoalb

40、urnershavebeendevelopedinasimilarfashiontotheoilburners,andconsiderableemphasisisplaceduponfeedingeachburnerwithcarefullyregulatedamountsofcoalandoil.Allcoalfiredboilersintheutilityfirepulverizedcoal(producedbymilling)whichisveryfinelydividedcoalcarriedtotheburneronastreamofair(primaryair).Thedesign

41、effortdirectedatflowequalizationhasproducedboilerswhichcanbeoperatedatlowerexcessairlevelsthanpreviously,andthushaveincreasedoverallefficiencywithoutincreasingunbumedcarbonlevelsintheash.燥燃烧系统燥燃烧器的发展模式同油燃烧器类似，而且重点放在准确控制每只燃烧器燥和油的供给量。实际中所有的燃煤锅炉都是燃烧煤粉(由磨煤机生产)，这些燥粉经过很好的粉碎，然后由空气流(一次风)送入燃烧器。同以前相比，在流动平衡上的设

42、计成果现在已能使锅炉在较低的过量空气水平下运行，并在不增加飞灰含碳量水平的情况下提高了总的效率。This,whencombinedwiththedevelopmentoflowNOXburnerswillresultinreducedgaseousemissioninlinewithEECdirectivesandisthemainobjectiveoftwoboilerconversions(bothcomplete)toestablishtheleveltowhichNOXmaybereducedintheexhaustfrom500MWcoalfiredboilers.ANOXreduc

43、tiondevelopmenttrialisproposedonathirdboilerdesign,汶样，结合低NOx燃烧器的开发，就使气体排放达到欧共体的标准，这也是两代锅炉转换(已完成)的主要目的，即设定500MW燃煤锅炉可能达到的NOx排放水平。在第三代锅炉的设计中进行了进一步降低NOx的开拓性试验。Thearrangementofcoal-firedsystemcomponentsmustbedeterminedaccordingtoeconomicfactorsaswellastheattributesofthecoal.Theperformanceintermsofproduct

44、fineness,milloutlettemperature,andair-coalratiomustallbedeterminedaspartofoverallcombustionsystemdesign.燥燃烧系统部件的布置必须根据经济因素和煤的性质来确定。作为整个燃烧系统设计的性能参数，煤粉细度、磨煤机出口温度、空煤比等都必须达到要求。LowNOXcombustionsystemsThefactorsaffectingNOXaretheproportionofnitrogenchemicallycombinedwiththefuel,peakflametemperature,theava

45、ilableoxygenintheflameandtheresidencetimeofthegaseswithinthesystem.Someofthecoalboundnitrogenisreleasedasvolatilesasthechemicalstructureofthecoalbreaksdownonenteringthefurnace.Nitricoxideproducedfromatmosphericnitrogenas"thermalNOx“canbelimitedbyminimizingresidencetimesathightemperature,whichli

46、mitingtheamountofoxygenavailabletothefuelduringthecombustionstageresultsintheproductionofharmlessnitrogenratherthanNOX.低NOx燃烧系统影响NOx生成的因素包括燃料含氮量、火焰峰值温度、火焰中的可用氧量以及气流在锅炉系统中的停留时间。当煤进入炉膛其化学结构被破坏时，一些煤中的化合氮就作为挥发分被释放出来。由大气中的辄生成的一氧化氮即“热力型NO.，可以通过减少烟气在高温区域的停留时间而得到控制，这样就会控制燃烧阶段中可用氧量，最后生成的是无害氮而不是NOxoSincecoalf

47、iringrequiressomeexcessoxygeninthecombustionzonetoachievetotalcarbonburnoutandnitrogenfreecoalisunavailable,NOXreductionhastobeperformedbyboilerandburnerdesign.因为煤在燃烧区的燃烧需要一定的过量氧气以便使所有的碳燃尽,且不含氮的煤是难以获得的，因此NOx的减少必须依靠锅炉和燃烧器的设计来完成。教材28页GascombustionsystemsNaturalgashasbeenfiredatpowerstationsformainload

48、purposes.However,gashasnotbeenavailabletotheutilityforsomeyearsnowanditisnotenvisagedthat,asapremiumfuel,itwilleverbeavailableagaininanyquantity.Propaneiswidelyusedinignitersfortheoilburnersinbothmainoilandcoalfiredboilers.天然气燃烧系统天然气曾经作为电厂主要燃料。然而一些年来，没有太多的天然气可供电厂使用，并且人们没有正视这样的事实，即天然气作为一种优质燃料将会重新得到大量

49、:应用。丙烷常常作为一种点火剂，广泛地应用于燃油锅炉和燃燥锅炉中的汕燃烧器。23.3Fluidized-bedcombustionAvariationonPCcombustionisfluidizedbedcombustioninwhichcoalisburnedwithairinafluidbed,typicallyacirculatingfluidizedbed(CFB).CFBsarebestsuitedtolow-costwastefuelsandlow-qualityorlowheatingvaluecoals.Crushedcoalandlimestonearefedintothe

50、bed,wherethelimestoneundergoescalcinationtoproducelime(CaO).Thefluidizedbedconsistonlyoflime,withafewpercentcoalandrecirculatedcoalchar.Thebedoperatesatsignificantlylowertemperatures,about427(800°F),whichthermodynamicallyfavorslowNOXformationandSO2capturebyreactionwithCaOtoformCaSO4.Thesteamcyc

51、lecanbesubcriticalandpotentiallysupercritical,aswithPCcombustion,andgeneratingefficienciesaresimilar.TheprimaryadvantageofCFBtechnologyisitscapacitytocaptureS02inthebed,anditsflexibilitytoawiderangeofcoalproperties,includingcoalswithlowheatingvalue,highashcoalsandlowvolatilecoals,andchangesincoaltyp

52、eduringoperation.Severallignite-burningCFBunitshavebeenconstructedrecently,andCFBsarewellsuitedtoco-firingbiomass.2.3.3流化床燃烧沆化床燃烧是燥粉燃烧方式的一种，采用这种燃烧方式时煤在空气中的燃烧发生在流化床中，典型的是循环流化床。循环流化床最适合于燃烧低成本废弃燃料、低品质或低热量煤。将煤粒和布灰布投入到床中，布灰布在床内煨烧成石灰。流化床中主要是石灰和少量的煤，煤焦在其中循环。运行中的床温很低，只有427(800T),在这个温度下的热力学环境有利于减少NOx的形成和捕集SM

53、使之与CaO反应生成CaSCU对于煤燃烧，蒸汽循环可以是亚临界，也可能是超临界，它们具有相近的发电效率。循环流化床技术的最大的优点是它在床中捕捉S02的能力和它对煤质的广泛适应性，其中包括低热量燥、高灰分燥和低挥发分煤，并且在运行中可以改变煤种。循环流化床锅炉适合与生物质共燃，最近就新建了几台燃烧褐燥的循环流化床机组。ThemostcommonlyusedcirculatingfluidizedbedcombustorisshowninFig.2-1.Coalandcoalcharareburnedwhilethecoal,coalchar,coalashandsorbentarecarrie

54、dupthroughthefurnacebycombustionair.Thesolidmaterialsareseparatedfromthefluegasin图2-1循环流化床锅炉设计布置实例教材29页thecycloneandpassthroughaconvectivesectionwhereheatistransferredtoboilertubesgeneratinghigh-pressuresteam.Additionalsteamisgeneratedbyremovingheatfromthehotsolidsinthefluidizedbedheatexchangesectio

55、nbeforetheyarereturnedtothefurnace.Therearenoboilertubesinthelowerfurnacebecausetherapidmovingsolidscauseexcessiveerosion.NOXismanagedthroughlowtemperatureandstagedinjectionofthecombustionair.SOXemissioniscontrolledviathelimesorbentinthebed.Thissavessignificantcapitalforfluegascleanup,butlowSOXemiss

56、ionrequirelow-sulfurcoal,andNOXemissionsarelimitedbycombustionchemistry.Extremelylowemissionslevelswouldrequiretheadditionoffluegasclean-upunitswiththeattendantcostincrease.ThelargestCFBunitis33OMWeinChina,and600MWunitshavebeendesigned,butnounitofthissizehasbeenbuilt.如图2所示，目前最常用的流化床技术是循环流化床燃烧技术。煤和煤焦

57、燃烧的同时，空气携带煤、煤焦、煤灰和脱硫剂通过炉膛。固体材料通过旋风分离器从烟气中分离出来，然后通过对流烟道部分，烟气把热量传给炉管以产生高压蒸汽。另一部分蒸汽是由流化床中的高温固体在返回炉膛前放出热量产生的。炉膛内固体快速运动会引起过量的磨损，因此炉膛底部不安装炉管。通过低燃烧温度和空气分级燃烧来控制NOx的生成。SOx排放通过床中石灰脱硫剂控制。这些为烟气净化节省了大笔的投资，但是低的SOx排放需要燃烧低硫分煤，并且NOx的排放受燃烧反应的限制。极低的排放需要额外的烟气净化设备，同时会增加相应的维护成本。在中国最大的流化床锅炉是33OMWe,设计最大的锅炉是600MWe,但是还没有投建。2

58、.4PulverizingSystemThedevelopmentandgrowthofcoalpulverizationcloselyparallelsthedevelopmentofpulverizedcoal-firingtechnology.Inordertoachieveefficientcombustionintheboilerfurnacethecoalleavingtheburnermustbesizedsothatitcanbumrapidlyandthismeansthatitmustbeintheformofsmallparticlesthatcanquicklybeheateduptoignitiontemperatur