锅炉培训.ppt

2021/3/24,1,提高锅炉热效率的途径Theofimprovingthermalefficiencyofaboiler,2021/3/24,2,一、概述Generalintroduction提高锅炉热效率的基本方向Thebasicofimprovingthermalefficiencyofaboiler,提高锅炉热效率有两个基本方向Thetwosidesofimprovingthethermalefficiency1.提高燃烧效率，降低不完全燃烧热损失q3和q4。Loweringtheheatlossduetounburnedq3andq4toimprovethecombustionefficiency.链条炉的远大于q3，因此，重点要抓q4的降低。Theefficiencyoftravelinggrateissurpassq3more,sothefocusiscutq4down.,2021/3/24,3,2.提高传热效率，降低排烟热损失和散热损失。Loweringtheheatlossduetoexhaustgastoimprovingtheefficiencyofheattransfer.排烟热损失常为使锅炉热效率降低的另一主要因素，而一般散热损失较小。Theothermainelementofreducingtheboilerefficiencyistheheatlossduetoexhaustgas,butthenormalheatlossduetoradiationisless.,2021/3/24,4,二、提高锅炉燃烧效率（以层燃炉为例）ImprovingboilercombustionefficiencyLayerburningfurnaceasanexample,1.燃料燃烧的基本概念Thebasicconceptoffuelcombustion1）燃烧combustion燃料中的可燃物质与空气中的氧在一定温度下发生剧烈的化学反应，发出光和热的现象。Combustiblematerialinthefuelandoxygenintheairtoacertaintemperature,theoccurrenceofviolentchemicalreactionsentthephenomenonoflightandheat.2）燃烧的三个条件Threeconditionsforcombustion有可燃物、空气、达到可燃物的着火的温度。Theyarefuel、airandfueltoreachthetemperatureofthefire.,2021/3/24,5,3）完全燃烧的条件Combustionconditions（同时具备以下条件）Atthesametimeareasthefollows燃烧温度，达到着火点并保持一定的温度，能连续燃烧直至燃尽；足够的空气量；良好的混合；充分的燃烧时间在不同的燃烧阶段将由其中的一个或两个要素起主要作用。Combustiontemperature,reachingignitionpointandmaintainingacertaintemperature,cancontinuetoburnuntiltheburning;enoughair;wellmixingandfullofburningtimeofwhichwillbeoneortwofactorsplayamajorroleindifferentstagesofcombustion.,2021/3/24,6,4）燃烧过程Thecombustionprocessisdividedintothreephases（分为三个阶段）着火前的热力准备阶段；着火燃烧阶段；燃尽阶段。Thermalpreparationphasebeforethefire;ignitedstage;burnstage,2021/3/24,7,2.层燃炉链条炉的工作特点Thecharacteroflayerburningfurnaceandtravelinggratefurnace链条炉为单面点火的炉子，着火由上而下进行，着火条件比较差，煤层与炉排无相对运动。Travelinggrateisignitedtoonesideofthefurnace,top-downfire,fireconditionsarerelativelypoor,coalandgratewithnorelativemotion.因为煤是加在空炉排上，送入冷空气，温度低于200℃，不能满足着火前热力准备阶段所需的热量，挥发分较少的无烟煤或劣质煤、水分多的煤等都不易着火，适宜燃用烟煤。,2021/3/24,8,,,,Ⅰ-新燃料区；Ⅱ-挥发物析出、燃烧区；Ⅲa-焦炭燃烧氧化区；Ⅲb-焦炭燃烧还原区；Ⅳ灰渣形成区,2021/3/24,9,3.链条炉实际运行常存在的问题Theprobleminoperationoftravelinggratefurnaceregularly1）利用煤仓供煤，煤的向下垂直压力较大，与煤闸板挤压形成的煤层比较密实，透气性差。Whenthecoalissuppliedwithcoalstore,thecoaledwiththepressureofcoalbrakeiscompactandpoorventilation.2）炉排上的煤层都是些颗粒大小不等混合在一起构成的煤的粒径无序掺混。Thecoalonthegrateisconsistedwithmixedparticleofvariablesizescoalisblendeddisorderinsize,2021/3/24,10,3）沿炉排方向两侧块状煤多，而细碎煤粒则在中部较多，造成Bothsidesofdirectionalongwiththegratearealotofmassivecoalandmorefinecoalparticlesinthemiddle,cause炉排上通风分布不均，易形成火口或漏煤量较大Ventilationonthegratedistributesunevenly,toeasilyburnerorleakmorecoal；炉排两侧易漏入冷空气，炉膛过量空气系数上升Onbothsidesofthegrateeasilyleakintothecoldair,andthefurnaceexcessairratioisincreased；降低炉温，煤不易烧透，排渣含碳量高Lowerfurnacetemperature,thecoalisburnedthroughhardly,andtheslagwithhighcarboncontent；锅炉效率和出力下降Boilerefficiencyandoutputwilldecline.,2021/3/24,11,3.改善层燃炉燃烧的措施Themeasuresofimprovingthelayerburningfurnace,1）设前、后拱Setfrontandreararch改变气流上升方向，使可燃气体与空气良好混合，将炉内热量尽量向炉前反射，加速新燃料的着火。特别是前拱Changingthedirectionofrisingaircurrents,sothatthecombustiblegasescanmixedwiththeairwell,tokeeptheheatinfurnacereflectedtotheforthasmuchaspossible,tospeedupthenewfueltofire引燃拱，反射烟气投射来的热量。在前后拱间形成“喉口”，使生成的气体在喉部加强混合。Archfirereflectstheheatprojectedfromgas.Throatisedbetweenfrontarchandreararch,tostrengthenthemixtureoftheedgasinthethroat.,2021/3/24,12,拱的形状和尺寸与燃料的性质有关。Theshapeandsizeofthearcharerelatedtothecharacterofthefuel.燃用低挥发分的无烟煤采用低而长的后拱。Thelowandlongreararchisadoptedtothefueledcoalstonewithlowvolatilization.燃用高挥发分的褐煤和烟煤采用高而短的后拱Thehighandshortreararchisadoptedtothefueledcoalandlignitewithhighvolatilization。,燃用褐煤、烟煤的链条炉,燃用无烟煤的链条炉,2021/3/24,13,2）分区送风Zonecontroldraft链条炉排上燃烧过程沿炉排方向所需的空气量是不同的“分段送风”，使送入的风量与需要的风量吻合。Intheprocessofcombustiononthegrate,therequiredamountofairalongthedirectionofthegrateisdifferent.zonecontroldraftmakethevolumeofairflowdeliveredtocoincidewiththeneeded.着火前准备阶段基本不需空气Thereisnoneedforairbasicallyinthestageofpreparationbeforefire.挥发分和焦炭燃烧区需大量空气Intheareaofcokecombustionandvolatileneedsalotofair.灰渣形成阶段需要少量空气Inthestageofslagationneedsasmallamountofair.,链条炉空气分布情况,2021/3/24,14,３）设二次风Setsecondaryair在喉部设二次风，加强扰动和混合，降低q３．Settingsecondaryairinthethroat,toreinforceagitationandmixture,toslowerq３.风量为总送风量的515Thevolumeofairsuppliedaccountsup515tothetotal；风速为5080m/sWindspeedfor5080m/s；工质可为空气、烟气、蒸汽。Therefrigerantforair、gasorvapor.,1-前拱Fortharch2-后拱Reararch3-喉口Throat4-二次风Secondaryair,2021/3/24,15,4）向炉内送热风Ventilateheatedairtothefurnace尾部加空气预热器Addairheateratrear5）采用合适煤种和粒度Useappropriatecoalandthesize燃用设计煤种Burningthecoaldesigned高挥发分的煤,水分控制在810Thehighvolatilecoal,watercontrolinthe8to10；灰分,干燥基灰分≤30Ash,dryash≤30；灰的熔化温度t3≥1200℃Theashmeltingtemperaturet3≥1200℃；粒度2030mm，均匀Size2030mm,uni；煤层厚度100150mmThicknessofcoalis100150mm.,2021/3/24,16,三、燃烧技术简介Thebriefintroductionofcombustiontechnology,1.链条炉分层燃烧技术Thetechnologyofhierarchicalcombustioninthetravelinggratefurnace1）分层燃烧装置的结构（见图）Thestructureofhierarchicalcombustioninstallation2）分层燃烧装置的工作过程Theprocessofhierarchicalcombustioninstallation.在溜煤管的出口加装给煤器，使炉排上煤层按不同粒度范围分成二层或三层，避免了煤层密实、粒径无序掺混带来的缺点，提高效率和出力及煤种的适应性。Addattheexitof,todividethecoalonthegrateintotwoorthreelayersaccordingtothescopeofparticles,toavoidthedefectsfromcoalcompactingandparticlesmingleddisorderly,toimproveefficiencyandeffort,adaptabilityofthecoalandsoon.,2021/3/24,17,滚筒分层给煤机（ZL95233823.8）1-落煤斗2-给煤斗3-分煤斗4-单层复合筛5-耐火砖6-后梁7-链条炉排8-弹力挡煤板9-槽钢架10-弹簧11-螺栓12-挡煤板13-丝杆14-折低的筛条15-托板16-滚筒17-筋条18-传动带,筛子的结构1-筛板2-梳齿状筛条3-折低的筛条,2021/3/24,18,3）特点Character使落煤疏松，按粒度分离分档，按颗粒大小有序排列、均匀分布，提高燃烧效率，降低q4。Thecoaldroploosely,accordingtothesizeseparated,bythesizeoftheparticlesarrangedorderly,distributedunily,improvingcombustionefficiency,cuttingq4down.,2021/3/24,19,2.煤与炉渣混烧Co-firingofthecoalandslag在煤中掺入颗粒较大的渣（煤渣比为41）减少通风阻力，增加了煤层的透气性，使送风均匀，提高燃烧的稳定性，降低q4。Thecoalmingledwiththelargerparticlesofslag，reducingtheresistanceofventilation,increasingthepermeabilityofthecoal,ventilatinguni,improvingthestabilityofthecombustion,cuttingq4down.注意煤层要加厚，炉膛温度会略有下降。AttentionIfthecoalthickening,thetemperatureoffurnacewilldropslightly.,2021/3/24,20,3.过量空气系数的优化Optimizationofexcessairratioα值的大小对燃烧及q2、q3、q4均有影响，一实例测试数据表明，α存在一优化值使Q2、q3、q4andcombustionareallundertheinfluenceofthescaleofthueofa,Oneexampleoftestdatashowthattheexistenceofoptimizethueofαmeet如图,过量空气系数由烟气分析测得烟气中的含氧量O2，根据下式计算炉膛出口处的过量空气系数αExcessairratiomeasuredbytheanalysisofthegasintheoxygencontentofO2,tocalculateexcessairratioαinthefurnaceexitaccordingtotheequationasfollowed,2021/3/24,21,4.循环流化床燃烧Circulatingfluidizedbedcombustion洁净燃烧技术Cleancombustiontechnology1）流化床Fluidizedbed流化床的工作过程Theprocessofthefluidizedbed将物料放在有空隙的箅板上，从箅板部通过箅或间隙向料层通入空气，当颗粒的重力大于气流推力时颗粒静止在箅板上，料层不动，为固定床。Materialsareputonthegrateplatewithgaps,thelayerofmaterialsareventilatedairthroughandgaps,ifthegravityofparticlesisgreaterthanthethrustofairflow,theparticleswillbestaticontheboardandthelayerofmaterialsismotionlessalso,sothatisdefinedasafixedbed.,,2021/3/24,22,若风速增加，料层膨胀，当风速超过某值，料层的稳定性被破坏，而被风托起，且颗粒上下不停地翻腾，这种处于松散沸腾状态的料层成为沸腾床或流化床，开始形成流化床的风速称为沸腾临界风速。Thelayerofmaterialswillexpandbytheincreasingofwindspeed,whenthewindspeedexcessavalue,thelayerofmaterialswillbedistructedinstabilityandholdupbythewind,writhingofparticlesupanddown,then,thelayerofmaterialsinthestateofboilingandlooseisdefinedasboilingbedorfluidizedbed.Thelayerofmaterialsledtotheationoffluizedbedisdefinedasboilingcriticalwindspeed.,2021/3/24,23,达到临界风速后，再增加风速至某值，固体颗粒不再上下翻腾而是被吹走了，就形成了气力输送，如图。达到气力输送时开始的风速为极限风速。风速在临界风速和极限风速之间都可形成流化床。Afterachievedcriticalwindspeed,ifincreasingthewindspeedtoavalue,solidparticalsarenolongerwrithingupanddownbutblownoff,thuspneumaticconveyingised.Thewindspeedatthebeginningofpneumaticconveyingisdefinedaswindspeedlimit.Thefluidizedbedcanbeedbetweencriticalspeedandwindspeedlimit.,2021/3/24,24,沸腾临界风速Boilingcriticalwindspeed，极限风速Windspeedlimit,2021/3/24,25,2）循环流化床锅炉Circulatingfluidizedbedboiler循环流化床锅炉就是在锅炉体内装有旋风分离器，从炉膛出来的烟气首先经分离器，将烟气中的固体颗粒收集，并送返炉内在进行燃烧，固体颗粒这样循环燃烧，使燃烧效率很高，也就提高了锅炉的热效率。同时向炉内加石灰石粉进行燃烧中脱硫。CFBboilerisequippedwithacycloneinthebody.Thesolidparticlesarecollectedtocyclonewhenthegascomingoutoffurnacepassthroughcycloneandreturnedinfurnaceburnning.Suchcirculatingcombustionofsolidparticleskeepcombustionefficiencyhighly,andthenimproveboilerefficiency.Atthesametime,limestonepowderaddedtothefurnaceforcombustiondesulfurization.,2021/3/24,26,循环流化床锅炉的优点Theadvantagesofcirculatingfluidizedbedboiler1）燃料适应性强Theadaptableoffuelwell；2）可回收烟气中的碳粒，燃烧效率高，可达95，高于层燃炉、低于煤粉炉。Recoverycarbongrainofthegas,High-efficiencycombustion,upto95,morethan,lessthanpulverizedcoal3）对负荷变化适应性好，低负荷时可转换为鼓泡流化床，最低在2530额定负荷下仍可以运行，负荷调节速率快，操作灵活。Adaptivetochangeinload.Runninginlowloadcanbeconvertedintobubblingfluidizedbed,aminimumof25to30oftheratedloadcanstillrun,rateofloadregulationfast,flexibleoperation.,2021/3/24,27,4）可采用较小的空气过量系数，传热效果好，热效率高，可达85以上。炉子的热强度高，炉体紧凑。Excessaircoefficiencyadoptedsmaller,effectiveheattransfer,boilerefficiencyhighly,above85.Heatintensityinfurnacehighly,furnacecompactly.5）循环流化床锅炉固硫后的灰渣有较好的强度，在制成混凝土时还有补偿收缩或实现微膨胀的功能，降低水化热核提高流动性。TheslaggeneratedafterdesulfurizationofCFBboilerisintensityhighlyandfunctionedofcompensationcontractionortherealizationofmicro-expansionintheconcretemaking.,2021/3/24,28,6）脱硫脱氮的效果好，由于料层燃烧温度低，维持在850℃900℃，是CaCO3分解和SO2与CaO化合的最佳温度，石灰石粉比表面积大，又是沸腾燃烧，能与SO2充分接触，由于空气过量系数小，NOX生成量较少。因此循环流化床燃烧被称为“洁净燃烧技术”。Effectiveindesulfurizationanddenitrification,Duetolayerofmaterialscombustinginlow-temperature,maintainedat850℃900℃,isthebesttemperaturefordecompositionofCaCO3andthecombinationofSO2andCaO,thelimestonepowderwithgreatspecificsurfaceareaandboilingburningcancontactwithSO2fully,duetothesmallexcessiveaircoefficient,NOXgenerateless.Therefore,circulatingfluidizedbedcombustion,knownas“cleancombustiontechnology.“,2021/3/24,29,循环流化床锅炉的缺点Theshortcomingsofthecirculatingfluidizedbedboiler1）排尘量大，需用电除尘才能达到环保要求，增加了锅炉房的初投资。ThequantityofdustemissionissolargethatitneedsESPtomeettherequirementofenvironmentalprotection,sothatwillincreasetheinvestmentintheearly.2）循环流化床锅炉烟气中的固体颗粒的浓度较高，水冷壁、分离器、面料系统及锅炉内衬、特别是炉内埋管磨损严重。TheconcentrationofsolidparticlesintheCBFboilergasishigher,andtheabrasioninthewatercooledwall,seperators,fabicsystemandboiler-linedisserious,especiallyinthefurnacepipe.,2021/3/24,30,3）循环流化床锅炉的耗电量大，费用较高，约为链条炉的两倍。因需将煤破碎为010mm的细粒，将石灰磨成0.10.3mm的细粉；采用高压风机、电除尘要耗电，购买石灰石也需费用。Theconsumptionandexpenditureofcirculatingfluidizedbedboilerisastwiceastravlinggrate.Socoalwillbebrokenforthe010mmfineandlimewillbegroundintofinepowderof0.10.3mm.TheexpenditureincludesusinghighpressurefanandESP,andalsothecostofthepurchaseoflimestone.4）炉墙的严密性要求高，密封性差会形成漏灰、漏风。Tightnessofthefurnacewallhigh,Poortightnesswillinducealeaktightnessgray,theairleakage.,2021/3/24,31,四、提高传热效率Improvingtransferefficiency（需要细化展开论述）,1.受热面的合理布置避免烟气短路Therationalarrangementofheatingsurfacecanavoidgasshortcircuit.1）受热面的合理分配与布置Therationalallocationandarrangementofheatingsurface.辐射受热面受热强度远大于对流受热面；Theheatintensityofradiantheatingsurfaceislargerthanconvectionheatingsurface.锅炉对流管束中是近于饱和温度的锅水，而烟气流过对流管束温度越来越低，过多地布置对流管束，其末端温差减小，传热效果降低。Thewaterintheconvectiontubebankarenearsaturationtemperature,thetemperatureofthegasflowconvectiontubebankismoreandmorelower,iftheconvectiontubebankarrangedtoomuch,thatdifferenceintemperaturewillreduceandeffectofheattransferwilllower.,2021/3/24,32,因此常在锅炉尾部设置省煤器及空气预热器等尾部受热面。辐射受热面、对流受热面及尾部受热面三者的分配是否恰当，是影响锅炉传热效率及经济性的重要因素。Sotherearheatingsurfaceincludingeconomizerandairheaterareusuallysetintheboilerrear.Whetherthedistributionofradiantheatingsurface,convectionheatingsurfaceandrearheatingsurfaceappropriateornotisanimportantfactortoaffecttheheattransferefficiencyofboilerandeconomy.,2021/3/24,33,锅炉对流管束受烟气冲刷，其排列方式（顺排或错排）、流动方式（顺流或逆流）以及与烟气冲刷的方式（横向冲刷或纵向冲刷）对放热系数都有很大影响。管束的布置还与流动阻力及水循环等因素有关。Thearrangementshunroworstaggeredarrangement,typeofflowfaircurrentorreversecurrent,aswellasthewayofwashinglateralorverticalerosionwashedofconvectiontubebankofboilerwhichiswashedoutbygashasastrongimpactonheatemissioncoefficient.Thearrangementoftubesisrelatedtothefactorsofwatercycleandflowedfriction,andsoon.,2021/3/24,34,,,2021/3/24,35,2）防止隔墙损坏造成烟气短路Topreventtheshortcircuitofgascausedbythedamageofthewall在对流管束间常用砖或耐火材料砌成隔墙，是烟气沿一定的路线流动，保持与管束正常地冲刷。若这些隔墙损坏，就会造成烟气短路，使一部分受热面得不到冲刷，而传热量减少，烟气离开受热面的温度增高，q2热损失增加。Partitionwasusuallypiledbybricksorfireresistantmaterialbetweenconvectionbanks,gasflowinacertainroute,maintainingnormalerosion.Smokeshort-circuitthatleadstoapartofheatingsurfacewithouterosion,andthenreduceheattransfercapacity,increasethetemperatureofgasdepartingfromheatingsurface,increaseheatlossq2.,2021/3/24,36,2.增加尾部受热面，回收烟气的余热；Increasetherearheatingsurface,recoverythewasteheatofgas1）控制排烟热损失及烟气余热回收Tocontrolheatlossduetoexhaustgasandrecoverthewasteheat优化α值及排烟温度，控制排烟热损失。Tooptimizethueofαandthetemperatureofexhaustgas,controlheatlossduetoexhaustgas.2）加装换热设备回收烟气余热如热管换热器Toinstallheattransferequipmenttorecoverthewasteheat,takeheatpipeheatexchangerforanexample.,2021/3/24,37,3.保持受热面内部的洁净，减少管内传热热阻Maintainthecleanlinessoftheinternalheatingsurface,reducingheatpipethermalresistance1）加强水处理防止结垢StrengtheningthewatertreatmenttopreventscalingCa、Mg水垢导热性能很差比钢小30～50倍thescalethermalconductivityofCa、Mgperpoorlylessthansteelfor30～50times，使排烟温度升高，降低锅炉的出力和效率。Raisingtheexhausttemperature,reducingoutputandefficiencyoftheboiler.,2021/3/24,38,根据试验，在汽锅内壁附着1mm厚的水垢，就要多消耗煤2％～3％左右。同时，受热面的壁温大为增高，引起金属的过热而使其机械强度降低，导致管壁起疱或出现裂缝。Accordingtothetest,thesteamboileradheredwithscaleofthicknessof1mmwillconsumethecoalaround2％～3％more,atthesametimetoincreasethewalltemperatureofheatingsurface,tocausemetaloverheatingandthenreduceitsmechanicalstrengthandleadtothewallblisteredorcracked.,2021/3/24,39,锅炉水管内壁结垢后，使管内流通截面减小，水循环的流动阻力增大，影响循环回路正常工作，甚至会堵塞水管，导致管子烧损。Afterscalingintheboilerpipewall,toreducetheflowofcross-sectioninthepipe,toincreasetheflowresistanceofthewatercycle,toaffectthenormalcirculationloop,oreventoplugthepipeandleadthepipetoburning.,2021/3/24,40,我国国家质量技术监督局于2001-01-10批准，2001-10-01实施的低压锅炉水质标准中规定“承压热水锅炉给水应进行锅外水处理，对于额定功率小于等于4.2MW非管架式承压的热水锅炉和常压热水锅炉，可采用锅内加药处理，但必须对锅炉的结垢、腐蚀和水质加强监督”。Low-pressureboilerwaterqualitystandardsimplementedon2001-10-01andapprovedbytheStateBureauofQualityandTechnicalSupervisionon2001-01-10providesthatfeedwaterofpressurehotwaterboilershouldbetreatedoutsideofboiler,fortheratedpowerequaltolessthan4.2MWnon-possessionstyleofpressurehotwaterboilerandpressurehotwaterboiler,d,osingpotcanbedealtwith,however,theboilermustbescaling,corrosionandwaterqualitysupervision.,2021/3/24,41,2）保持凝结水及回水洁净Keepcondensationwaterandreturnwaterclean热水管网的回水，特别是直供系统的回水，所含的杂质多为散热器及管网中存在的污物及腐蚀产物，一般要求管网上的除污器性能可靠和经常冲洗即可。Theimpuritiesinthereturnwaterofthehotwaterpipenetwork,especiallyinthedirectsupplysystem,aremostlydirtandcorrosionproductsexistedintheradiatorandnetwork,andthedecontaminationinthenetworkrequiresperancereliableandwashedfrequently.,2021/3/24,42,3）锅炉和热网的冲洗及加强锅炉排污Towashtheboilerandnetworkandstrengthenblowdown.锅炉和热网竣工时要冲洗，冲洗水速要高于1m/s。Theboilerandnetworkwhicharecompletedneedtowash,andthespeedofingwaterismorethan1m/s.锅炉内的水渣应及时通过排污排出，