PMI培训资料：换热设备Heat Exchanger

换热设备HeatExchanger换热器一、概述在炼油、化工生产中，绝大多数的工艺过程都有加热、冷却和冷凝的过程，这些过程总称为换热过程。传热过程的进行需要一定的设备来完成，这些使传热过程得以实现的设备就称之为换热设备。据统计，在炼油厂中换热设备的投资占全部工艺设备总投资的35％～40％,因为绝大部分的化学反应或传质传热过程都与热量的变化密切相关，如反应过程中，有的要放热，有的要吸热，要维持反应的连续进行，就必须排除多余的热量或补充所需的热量；工艺过程中某些废热或余热也需要加以回收利用，以降低成本。另外，生产所得的油品或化工产品，需要将其冷却或冷凝，以便储存和运输。以上这些与热量有关的过程都需要使用换热设备。使用换热设备是为了达到加热或冷却的目的，如果将那些需要加热的流体与需要冷却的流体，经过换热设备相互换热，既可回收热量，又可降低冷却水的消耗。综上所述，换热设备是炼油、化工生产中不可缺少的重要设备。换热设备在动力、原子能、冶金及食品等其他工业部门也有着广泛的应用。HeatExchanger1.OverviewIntherefining,chemicalproduction,thevastmajorityofprocessesareheating,coolingandcondensationprocess.Theseprocessesarecollectivelyreferredtoasheattransferprocesses.Theheattransferprocessrequiresacertainamountofequipmenttocomplete.Thesedevicesthatenabletheheattransferprocesstoberealizedarereferredtoasheattransferequipment.Accordingtostatistics,intherefineryheattransferequipmentinvestmentaccountedfor35%to40%ofthetotalinvestmentinprocessequipmentbecausemostofthechemicalreactionormasstransferprocessarecloselyrelatedtochangesinheat.Examplesofthereactionprocessaresomehaveexothermic,andsomehaveendothermicinordertomaintainthecontinuousreaction,andhencewemustruleouttheexcessheatorsupplementtherequiredheat;somewasteheatorwasteheatintheprocessalsoneedtoberecycledtoreducecost.Inaddition,theresultingoilorchemicalproductneedstobecooledorcondensedforstorageandtransportation.Alloftheseheat-relatedprocessesrequiretheuseofheattransferequipment.Theuseofheattransferequipmentistoachievethepurposeofheatingorcooling,ifthosewhoneedtoheatthefluidandtheneedtocoolthefluid,heatexchangeequipmentthroughheattransfer,canrecoverheat,butalsoreducetheconsumptionofcoolingwater.Insummary,theheattransferequipmentistheoilrefining,chemicalproductionindispensableimportantequipment.Heatexchangerequipmentinthepower,atomicenergy,metallurgyandfoodandotherindustrialsectorsalsohaveawiderangeofapplications.

二、比较换热设备的指标

效率要高。效率高就要求其传热系数大，传热系数是指在单位时间内、单位面积上温度每变化一度所传递的热量。结构紧凑。要使换热设备的结构紧凑就要求其比表面积大，比表面积是指单位体积的换热设备所具有的传热面积，即传热面积与换热设备体积之比。节省材料。要做到此点要求其比重量要小，所谓比重量是指单位传热面积所耗用的金属量，即换热设备总金属用量与传热面积之比。压力降要小。流体在设备中流动阻力小、压力损失就小，节省动力、操作成本降低。要求结构可靠、制造成本低，便于安装、检修、使用周期长。由于要全面满足上述要求是非常困难的，因而产生了各种各样的换热器，以适应各种特定的工艺条件。2.ComparisonofheattransferequipmentindicatorsEfficiencyishigh.Highefficiencyrequiresalargeheattransfercoefficient,heattransfercoefficientreferstotheunittime,theunitareaofthetemperatureperpassoncetheheattransfer.Compactstructure.Tomakethestructureoftheheattransferdevicerequiresalargesurfacearea,thespecificsurfaceareareferstotheunitvolumeofheattransferequipmenthasaheattransferarea,thatis,heattransferareaandheattransferequipmentvolumeratio.Savematerial.Todothisrequiresasmallerthanitsweight,theso-calledspecificweightreferstotheunitheattransferareaconsumedbytheamountofmetal,thatis,heattransferequipment,thetotalamountofmetalandheattransferarearatio.Pressuredropissmall.Fluidinthedeviceflowresistanceissmall,thepressurelossissmall,savepower,reduceoperatingcosts.Requiresreliablestructure,lowmanufacturingcost,easytoinstall,repair,longusecycle.Itisverydifficulttofullymeettheaboverequirements,resultinginavarietyofheatexchangerstosuitavarietyofspecificprocessconditions.三、换热器的分类换热设备的分类方法很多，现将几种常见的分类方法介绍如下：1、按用途分类：分为热交换器、冷凝器、蒸发器、加热器及冷却器等五类。1）热交换器：两种不同温度的介质进行热量交换，使一种介质降温而另一种介质升温，以满足各自的需要。2）冷凝器：两种不同温度的介质进行热量交换，其中一种介质由汽态被冷凝成液态。3）蒸发器：与冷凝器的操作刚好相反，两种介质中的一种介质由液体被蒸发成汽体。4）加热器：只单纯的完成一种介质的加热升温的操作。5）冷却器：如果热量不回收利用，完成用冷却剂（如水、空气）来冷却另外一种介质的操作的换热器称为冷却器。如用空气作为冷却剂的换热器称为空气冷却器，简称空冷器。2、按材料分类：分为金属材料和非金属材料换热器。3、按结构分类：分为管壳式换热器和板式换热器。3.ClassificationofheatexchangersTherearemanywaystoclassifyheatexchangers.Severalcommonclassificationmethodsarepresentedasfollows:1,accordingtotheuseofclassification:dividedintoheatexchangers,condensers,evaporators,heatersandcoolersandotherfivecategories.1)Heatexchangers:Twodifferenttemperaturesofthemediumforheatexchange,sothatamediumcoolingandtheothermediumtemperaturetomeettheirneeds.2)Condenser:Twodifferenttemperaturesofthemediumforheatexchange,oneofthemediafromthevaporstateiscondensedintoliquid.3)Evaporator:Incontrasttotheoperationofthecondenser,oneofthetwomediaisevaporatedfromtheliquidintothevapor.4)Heater:justsimplyheatingonecompletemediumheatingoperation.5)cooler:Iftheheatisnotrecycled,thecompletionoftheuseofcoolants(suchaswater,air)tocooltheoperationofanothermediumheatexchangercalledthecooler.Suchastheairasacoolantheatexchangerknownastheaircooler,referredtoasaircooler.2,bymaterialclassification:metalandnon-metallicmaterialsintoheatexchanger.3,accordingtothestructureclassification:dividedintoshellandtubeheatexchangerandplateheatexchanger.1）管壳式换热器：特点是圆形的外壳中装有管束。一种介质流经换热管内的通道及其相贯通部分（称为壳程）。它可分为:浮头式换热器、U型管式换热器、套管式换热器、固定管板式换热器等。2）板式换热器：它是由压成各种形状的薄板组成传热面的，冷、热两种介质分别在相邻两板之间流动。常见的板式换热器有平板式换热器、伞板式换热器、螺旋板式换热器及板壳式换热器。板式换热器的传热效率虽然较高，但由于其强度低，密封性能差，故其应用受到了限制。因此，在石油、化工工业中应用较多的是管壳式换热器，它已被当成传统的换热设备来加以使用。1)shellandtubeheatexchanger:Featuresareroundshellwithtubebundles.Amediumflowsthroughthechannelintheheattransfertubeanditsintersectingpart(calledtheshell).Itcanbedividedinto:floatingheadheatexchanger,U-tubeheatexchanger,casingheatexchanger,fixedtubeplateheatexchanger.2)plateheatexchanger:itispressedintoavarietyofshapesofthecompositionoftheheattransfersurface,cold,heat,respectively,betweenthetwomediaflowbetweenthetwoplates.Commonplateheatexchangersareflatplateheatexchangers,umbrellaplateheatexchangers,screwplateheatexchangersandplateandshellheatexchangers.Plateheatexchangerheattransferefficiencyishigh,butbecauseofitslowstrength,poorsealingperformance,soitsapplicationhasbeenlimited.Therefore,intheoil,chemicalindustryismoreapplicationofshellandtubeheatexchanger,ithasbeenusedasatraditionalheatexchangerequipmenttobeused.四、管壳式换热器的总体结构1）固定管板式换热器这类换热器的结构简单，重量轻，造价较低，在相同的壳层情况下，可较其他型式的列管换热器多排一些传热管子。但是壳体与管程之间的流体的温差不能太大，因温差太大时，会产生较大的热应力，使管子与管板结合处松脱而产生泄漏。此外这类换热器因管板是固定的，所以在检修，更换管子或清洗壳层时，都比较困难。此换热器适用于壳程介质不易结垢，或是有结垢但可进行化学清洗的场合；壳壁与管壁因温度差而引起的膨胀量之差不大，或膨胀差虽大但壳程压力不高的情况。1)fixedtubeplateheatexchangerThestructureofsuchheatexchangersissimple,lightweight,lowcost,inthesameshellcase,comparedwithothertypesoftubeheatexchangerrowofsomeheattransfertube.However,thetemperaturedifferencebetweentheshellandthepipecannotbetoolarge,becausethetemperatureistoolarge,willhaveagreaterthermalstress,sothatthetubeandthetubeplateatthejunctionofthelooseandproduceleakage.Inaddition,suchheatexchangerbecausethetubeplateisfixed,sointhemaintenance,replacementofthetubeorcleantheshell,aremoredifficult.Thisheatexchangerissuitableforshellmediaisnoteasytoscale,ortherearescalingbutcanbetheoccasionofchemicalcleaning;shellwallandwallduetotemperaturedifferencecausedbytheexpansionofthedifferenceisnotlarge,orexpansiondifferenceislargeShellpressureisnothigh.4.Theoverallstructureofshell-and-tubeheatexchangers总体结构图OverallStructure2、管壳式换热器的总体结构以及特点2）浮头式换热器浮头式换热器的一端管板是固定的。与壳体刚性连接，另一端管板是活动的，与壳体之间并不相连。活动管板一侧总称为浮头，浮头式换热器的管束可从壳体中抽出，故管外壁清洗方便，管束可在壳体中自由伸缩，所以无温差应力；但结构复杂、造价高，且浮头处若密封不严会造成两种流体混合。浮头式换热器适用于冷热流体温差较大（一般冷流进口与热流进口温差可达110℃），介质易结垢需要清洗的场合。在炼油厂中使用的各类管壳式换热器中浮头式最多。1.shellandtubeheatexchangeroftheoverallstructureandcharacteristics1)FloatingheadheatexchangerOneendofthefloatingheadheatexchangerisfixed.Rigidlyconnectedtothehousing,theotherendofthetubeplateisactive,andtheshellisnotconnected.Thesideoftube-sheetisknownasthefloatinghead,floatingheadheatexchangertubebundlecanbeextractedfromtheshell,sothetubewalleasytoclean,thetubecanbefreeintheshelltelescopic,sonotemperaturestress;butthestructureiscomplex,Andifthemouthisnottightlysealedwillcausetwokindsoffluidmixing.Floatingheadheatexchangerforhotandcoldfluidtemperaturedifference(thegeneralcoldflowinletandheatflowtemperaturedifferenceofupto110℃),themedianeedtocleantheneedforcleaningoccasions.Intheuseofvarioustypesofshellandtubeheatexchangerinthefloatingheadtypeup.

总体结构图Overallstructure浮头式换热器和冷凝器，可采用内导流或外导流结构，管内均可承受高压。Floatingheadheatexchangerandcondenser,canbeusedwithinthediversionorexternaldiversionstructure,thetubecanwithstandhighpressure.内导流换热器结构图外导流换热器结构图内导流筒与外导流筒换热器的区别Ⅰ、内导流筒换热器是在换热器的壳程筒体内设置了内导流筒使换热器的前或后端未加导流筒前难以利用换热的换热管得以充分利用，从而增大换热器的有效换热面积。Ⅱ、外导流式换热器是在原换热器的壳程筒体上增加一个放大筒节用以扩散壳程流体，并使流体从换热器壳程的两端进入壳程，从而避免了在换热器布管时考虑布管弓形的高，而使增加了同规格上换热器的布管数目并有效利用了换热器前后端的换热管从而增大了有效换热面积。ThedifferencebetweentheinnerguidecylinderandtheexternalguidetubeheatexchangerⅠ,theinternalguidetubeheatexchangerisintheheatexchangershelltubebodyisprovidedwithintheinternalguidetubesothattheheatexchangerbeforeoraftertheendofthedrafttubeisnotdifficulttousetheheattransfertubetobesufficientUse,therebyincreasingtheeffectiveheattransferareaoftheheatexchanger.II,theexternalflow-typeheatexchangerisintheoriginalheatexchangershellsideofthecylindertoaddazoomtubesectiontodiffusetheshellprocessfluid,andthefluidfromtheheatexchangershellbothendsintotheshell,soastoavoidTheheatpipeintheheatpipewhenconsideringthehighangleofthetube,sothattheincreasewiththespecificationsoftheheatexchangeronthenumberofpipeandtheeffectiveuseoftheheatexchangerbeforeandaftertheendoftheheattransfertubetoincreasetheeffectiveheattransferarea.3）U型管式换热器这种换热器不同于固定管板式和浮头式，只有一块管板，换热管作为U字形、两端都固定在同一块管板上；管板和壳体之间通过螺栓固定在一起。这种换热器结构简单、造价低，管束可在壳体内自由伸缩，无温差应力，也可将管束抽出清洗且还省了一块管板；但U形管管内清洗困难且管子更换也不方便，由于U形弯管半径不能太小，故与其他管壳式换热器相比布管较少，结构不够紧凑。它适用于冷热流体温差较大、管内走清洁不易结垢的高温、高压、腐蚀性较大的流体的场合。3)U-tubeheatexchangerThisheatexchangerisdifferentfromthefixedtubeplateandfloatingheadtype,onlyatubeplate,theheattransfertubeasU-shaped,bothendsarefixedonthesametubeplate;tubeplateandtheshellbetweentheboltstogether.Thiskindofheatexchangerhastheadvantagesofsimplestructure,lowcost,freeexpansionandcontractionofthetubeintheshell,notemperaturestress,andcanalsotakeoutthetubeandsavethetubeboard;buttheU-shapedpipeisdifficulttocleanandthepipeisnoteasytobereplaced,BecausetheU-shapedbendradiuscannotbetoosmall,socomparedwithothershellandtubeheatexchangertubeless,thestructureisnotcompactenough.Itissuitableforhotandcoldfluidtemperaturedifferencebetweenthetubetogocleanandeasytoscalehightemperature,highpressure,corrosivelargefluidoccasions.总体结构图4）釜式换热器这种换热器的壳体直径一般为管束直径的1.5～2.0倍，管束偏置于壳体的下方，液面淹没管束，使管束上部形成一定的汽液分离空间。此换热器多用来做蒸发器、分馏塔的重沸器或简单的废热锅炉。根据需要，管束可以是固定管板型、浮头型或U型管型。4)kettleheatexchangerThediameteroftheheatexchangershellisgenerally1.5to2.0timesthediameterofthebundle,thetubebundleisplacedundertheshell,theliquidsubmergedtubebundle,sothattheupperpartofthetubetoformacertainvapor-liquidseparationspace.Thisheatexchangerisusedforevaporators,reboilers,orsimplewasteheatboilers.Thetubebundlemaybeeitherafixedtubeplatetype,afloatingheadtypeoraUtypetubetypeasrequired.5）折流杆管壳式换热器折流杆换热器主要特点是：壳程不再设置折流板，而由折流杆组成的折流圈来代替折流板，既对管子起支撑作用，又对流体起扰动作用，藉以达到强化传热的目的。折流杆管壳式换热器的结构特点：折流杆换热器的核心部分是由一系列焊有折流杆的折流圈组成折流圈笼。图5-1为折流圈的示意图。图5-2则为折流圈笼和管板的组装图。5)baffleshellandtubeheatexchanger

Themainfeaturesofthebaffleheatexchangerare:thebaffleplateisnolongersetupbaffle,andthebafflecomposedofbaffleinsteadofthebaffle,bothonthetubefromthesupportingrole,butalsotheroleofthefluidfromthedisturbanceToachievethepurposeofenhancedheattransfer.

Thestructuralcharacteristicsofthebaffle-typeheatexchangerare:Thecorepartofthebaffleheatexchangerconsistsofaseriesofbaffleswithabafflewithabaffle.Figure5-1isaschematicdiagramofthebaffle.Figure5-2showstheassemblyofthebafflecageandtubesheet.图5-1折流圈的示意图Schematicdiagramofthebaffle1—壳体Shell；2—折流圈Bafflering；3—折流杆Baffleroddbi、db0、d0—分别为折流圈的内径、外径和壳体内径theinnerdiameterofthebaffle,theouterdiameterandtheinnerdiameteroftheshell图5-2折流圈笼和管板的组装图BaffleringandcageassemblyofFIGtubesheet

从以上两图可以看出折流杆是均匀地焊在折流圈上，每一个折流圈侧相隔一定的距离，按一定排列分别焊接在拉杆上，从而形成一个折流圈笼。折流杆可以是圆形、方形或长方形。通常相邻两个折流圈的折流杆其方向是互相垂直的，即如果前一个折流圈的折流杆是垂直布置的，则后一个折流圈的折流杆就为水平布置。传热管穿过折流圈时可以有不同的情况，例如可以是两根折流杆中间夹一根传热管子，也可以是两根折流杆之间夹两根传热管。而且前后折流圈的折流杆与传热管之间也可以有不同的组合情况。Fromtheabovetwofigurescanbeseenthatthebaffleisevenlyweldedtothebaffle,eachfuselagesideseparatedbyacertaindistance,accordingtoacertainarrangementwereweldedtotherod,thusformingabafflecage.Thebafflecanberound,squareorrectangular.Normallythebafflesoftheadjacenttwobafflesareorientedperpendiculartoeachother,thatis,ifthebaffleofthepreviousbaffleisverticallyarranged,thebaffleofthesubsequentbaffleisarrangedhorizontally.Whentheheattransfertubethroughthebafflecanhavedifferentcircumstances,forexample,canbetwobafflesinthemiddlefolderaheattransfertube,itcanbebetweenthetwobaffletwoheattransfertube.Andthefrontandrearbafflebetweenthebaffleandheattransfertubecanalsohaveadifferentcombination.

例如前面折流圈的折流杆是水平地支撑第1、3、5-----排传热管，随后一个折流圈的折流杆则是垂直地支撑第2、4、6-----排传热管，然后依次交替布置。当然也可以有其它的组合和布置方式，但不论何种布置方式都必须保证每根传热管能被四个折流圈的四根折流杆从四个方向将其牢牢固定。折流圈中的折流环可以用圆杆、方杆或方条制作，其内径等于管束的外径，其外径则等于壳体内径减去设计标准所规定的间隙。折流环的形式有杆式、板式和带式三种。其中板式折流环的径向厚度大于纵向厚度，而带式折流环的径向厚度小于纵向厚度。Forexample,thebaffleofthefrontbaffleishorizontallysupportingthefirst,third,fifth,andquinteredheattransfertubes,followedbyabafflebafflethatverticallysupportsthe2nd,----dischargeheatpipe,andthenarrangedinturn.Ofcourse,theremaybeothercombinationsandarrangements,butnomatterwhatarrangementmustensurethateachheattransfertubecanbefourbafflesfourbafflesfromfourdirectionstofirmlyfixed.Thebaffleinthebafflecanbemadeofaroundbar,squarebarorsquarebarwhoseinnerdiameterisequaltotheouterdiameterofthetubebundleanditsouterdiameterisequaltotheinnerdiameteroftheshellminustheclearancespecifiedbythedesignstandard.Theshapeofthebaffleisrod,plateandbelt.Whereintheradialthicknessoftheplatebaffleisgreaterthanthelongitudinalthicknessandtheradialthicknessofthebeltbaffleislessthanthelongitudinalthickness.优点：①、不易发生诱导振动损失；②、传热死区小，传热效率提高20%以上；③、压降小；④、抗垢性能优良；⑤、有强化冷凝的机理；⑥、适用于换热器大型化，特别是在核电换热器应用；适用于冷凝、沸腾场合的换热器；⑦、适用于压缩机级间冷却和烟气预热器。缺点：①、在低雷诺数Re＜6000（液相）、Re＜10000（气相）热效率较低；②、造价提高3~5%。Advantage:①,itisnoteasytoinducevibrationloss;②,heattransferdeadzoneissmall,heattransferefficiencyincreasedby20%ormore;③,pressuredropissmall;④,excellentanti-foulingperformance;⑤,thereisamechanismtostrengthenthecondensation;⑥,suitableforlarge-scaleheatexchanger,especiallyintheapplicationofnuclearheatexchanger;forcondensing,boilingheatexchanger;⑦,suitableforcompressorinter-stagecoolingandfluegaspreheater.Disadvantages:①,lowReynoldsnumberRe<6000(liquidphase),Re<10000(gasphase)thermalefficiencyislow;②,thecostincreasedby3to5%.6）双弓形板换热器Doublearchedplateheatexchanger结构形式Structuretype双弓形板换热器与通常使用的单弓形板换热器相比，仅在于折流板形状的不同。双弓形折流板由A、B两种结构组成。Doublearchedplateheatexchangercomparedwithasinglearcuateplateheatexchangerisgenerallyusedonlyindifferentbaffleshape.DoublesegmentalbafflebyA,Bcomposedoftwostructures.6）双弓形板换热器性能特点双弓形板换热器的管束由相邻两种折流板组成支撑件，流体呈顺错流流动，从而克服了普通单弓形板换热器的壳程流体，在流动中的180度转弯所造成的死区、阻力大、易震动等缺陷。在相同壳程压力降下，双弓形板换热器壳程流体的流速一般可提高1.5倍以上，从而强化了传热。通过管束的阻力仅为单弓形扳换热器的1/5～1/8，因此减少板间距和壳径来提高流速是常用手段。6)DoublearchedplateheatexchangerCharacteristicsofitsperformanceDoublearchedplateheatexchangertubebundlefromthetwokindsofadjacentbaffleplatessupportmember,thefluidflowintheciscrossflowtoovercometheordinarysinglearcuateshell-sidefluidplateheatexchanger,the180-degreeturnintheflowofdeadzonecausedbytheresistance,vibration-proneandotherdefects.Pressuredropsinthesameshell,thearcuatedouble-flowplateheatexchangershellfluidisgenerallyincreasedmorethan1.5times,therebyenhancingheattransfer.Theresistancethroughthetubebundleisonly1/5to1/8ofthesingle-archedheatexchanger,soreducingtheplatespacingandtheshelldiametertoincreasetheflowrateisacommonmeans.7）螺旋折流板换热器Helicalbaffleheatexchanger

螺旋折流板换热器是管壳式换热器的一种形式。每块折流板占1/4的横截面积，呈螺旋状自进口至出口方向逐一布置。折流板对换热器中心线保持一定的倾斜角度，四块折流板完成360。内的旋转，这样在壳体内形成连续的螺旋，使流体流动接近柱塞流动。

Helicalbaffleheatexchangersareaformofshellandtubeheatexchangers.Eachbaffleaccountedfor1/4ofthecross-sectionalarea,wasspiralfromtheimporttotheexportdirectiononebyonearrangement.Thebaffleplatemaintainsacertaininclinationangletothecenterlineoftheheatexchanger,andthefourbafflesarecompleted360.,Sothatacontinuousspiralisformedinthehousingsothatthefluidflowsclosetotheplunger.螺旋折流板换热器基本原理及折流板形式螺旋折流板换热器的提出基于这样一种思想:通过改变壳侧折流板的布置，使壳侧流体呈连续的螺旋状流动。因此，理想的折流板布置应该为连续的螺旋曲面。但是，螺旋曲面加工困难，而且换热管与折流板的配合也较难实现.考虑到加工上的方便，采用一系列的扇形平面板(称之为螺旋折流板)替代曲面相间连接，在壳侧形成近似螺旋面，使壳侧流体产生近似连续螺旋状流动。一般来说，出于加工方面的考虑，一个螺距取2～4块折流板，相邻折流板之间有连续搭接和交错搭接两方式，按流道又可分为单螺旋和双螺旋两种结构。Basicprincipleofspiralbaffleheatexchangerandbaffleplateform

Thespiralbaffleheatexchangerisbasedontheideathattheshellsidefluidflowsinacontinuousspiralbychangingthearrangementoftheshellsidebaffles.Therefore,theidealbafflearrangementshouldbeacontinuoushelicalsurface.However,thespiralsurfaceprocessingisdifficult,andtheheattransfertubeandthebafflewiththemoredifficulttoachieve.Withtheconvenienceofprocessing,usingaseriesoffan-shapedflatplate(calledthespiralbaffle)insteadofcurvedsurfaceconnected,Andanapproximatelyhelicalsurfaceisformedontheshellsidesothattheshellsidefluidproducesanapproximatelycontinuoushelicalflow.Ingeneral,forprocessingconsiderations,ascrewfromthe2to4baffles,adjacentbafflesbetweenthecontinuouslapandstaggeredoverlapbetweenthetwoways,accordingtotheflowchannelcanbedividedintosinglehelixandDoublehelixtwostructures.性能特点：与普通的弓形折流板换热器相比，螺旋折流板换热器有以下的性能改进：①衡量换热效果好坏的综合效益系数(即传热速率与压力降的比值)有较大的提高：

ABB公司以水一水为介质，进行普通弓形折流板和螺旋折流板的传热与压力降实验对比，结果为：(a)螺旋折流板换热器壳程传热系数约提高1.8倍；(b)压力降减少约4.5倍。②壳程流体流动状态的改变：弓形折流板使壳程流体基本上处于横穿管子的错流流动，在90度转弯处易有固体颗粒堆积和结垢产生。而螺旋折流板每块折流板仅占1/4横截面积，与中心线有一定角度的倾斜。Features:

Comparedwithconventionalsegmentalbaffleheatexchangers,spiralheatexchangerbafflehasthefollowingperformanceimprovements:

①measuretheheattransfereffectofgoodorbadcomprehensiveefficiencycoefficient(thatis,theratioofheattransferrateandpressuredrop)havegreatlyimproved:

Theresultsshowthat:(a)theheattransfercoefficientoftheshellofthehelicalbaffleheatexchangerisabout1.8(1),andtheheattransfercoefficientofthecoilisimprovedby1.8%Times;(b)thepressuredropbyabout4.5times.②changesinshellfluidflowstate:

Thebafflecausestheshell-sidefluidtobesubstantiallyinacross-flowflowacrossthetube,withsolidparticlesaccumulatingandfoulingat90°turns.Andthespiralbaffleeachbaffleonly1/4cross-sectionalarea,andthecenterlinehasacertainangleoftilt.折流板按一定的间距和不同方位相继排列，使壳程流体呈旋转柱塞流动。这就消除了流动死区，减少了固体颗粒堆积和结垢的生成。因为没有横穿管间的流动，因此即使在较高的流速下也不易引起管子的振动。③较低的压力降允许流体提高流速，以使膜传热系数有较大的提高：因为壳程压力降仅为普通弓形折流板的1/4-1/5，故可以允许介质高速流过从而强化传热效果。在满足管程需求的同时，可以尽量提高壳程流动速度来提高膜传热系数。这样，螺旋折流板换热器需要精心设计，寻求适合的壳径与管长的比例，以达到提高总传热速率、减少换热面积的目的。④对于限制壳程压力降的设备，在利用原有壳径的基础上，螺旋折流板换热器可以发挥自身优势。Thebaffleplateisarrangedinacertainpitchandindifferentorientationssothattheshellfluidflowsasarotatingplunger.Thiseliminatestheflowdeadzone,reducingtheaccumulationofsolidparticlesandtheformationoffouling.Sincethereisnoflowacrossthepipe,itisnoteasytocausethevibrationofthetubeevenatahigherflowrate.

③lowerpressuredropallowsthefluidtoincreasetheflowrate,sothatthemembraneheattransfercoefficienthasgreatlyimproved:

Becausetheshellpressuredropisonly1/4-1/5oftheordinarybowbaffle,itcanallowthemediumtoflowathighspeedtoenhancetheheattransfereffect.Inordertomeettheneedsofthepipelineatthesametime,youcantrytoimprovetheshellflowratetoimprovethemembraneheattransfercoefficient.Inthisway,thespiralbaffleheatexchangerneedstobecarefullydesignedtofindtheappropriateratioofshelldiametertopipelengthinordertoachievethepurposeofincreasingthetotalheattransferrateandreducingtheheattransferarea.④shellforlimitingpressuredropdevice,basedontheuseoftheoriginaldiameteroftheshell,thehelicalbaffleheatexchangercanplaytheirownadvantages.8）螺纹锁紧环换热器螺纹锁紧环换热器，其结构主要由管箱、壳体、管束、管箱盖、固定环、螺纹锁紧环、压紧环、密封装置等零部件组成。一般设计压力8~20MPa，设计温度300~550℃，材料为2.25Cr-1Mo+347L或15CrMoR+321，是目前高压换热器设计难度高，制造难度大的换热设备，螺纹锁紧环换热器结构复杂，金属耗量大，机加工配合件较多。Thebreechlockclosuretypeheatexchanger,itsstructuremainlybythetubebox,shell,tubebundle,tubeboxcover,fixedring,threadlockingring,pressingring,sealingdeviceandothercomponents.Thedesignpressureis8~20MPa,thedesigntemperatureis300~550℃,thematerialis2.25Cr-1Mo+347Lor15CrMoR+321,whichistheheattransferdevicewithhighdesignandhighdifficultyinmakinghighpressureheatexchanger.Heatexchangerstructureiscomplex,metalconsumption,machiningwithmorepieces.密封结构——螺纹锁紧环

Sealingstructure-Thebreechlockclosure

1-管箱壳体；2-固定螺栓；

3-固定螺栓；4-管箱盖；

5-垫片压板；6-固定环；

7-螺纹锁紧环；8-压紧环；

9-管程垫片；10-压环；

11-内法兰；12-管程开口接管；

13-密封装置；14-管板；

15-传热管；16-壳体；

17-壳程开口接管；18-壳程垫片；19-分程隔板；20-内部固定螺栓；21-内套筒密封结构——螺纹锁紧环

Sealingstructure-Thebreechlockclosure优点：①、结构上安全可靠；

②、耐高温、高压，温度≤550℃，压力≤20MPa；

③、密封性能好；

④、结构独特；

⑤、壳壁与管束壁温差大，管束可自由伸缩，吸收膨胀差；

⑥、可拆卸、可清洗；

⑦、耐硫化氢腐蚀缺点：①、结构复杂，设计繁琐；

②、重量大，造价高；③、零部件较多，密封要求高；④、检修、维修量大。advantage:①,thestructureissafeandreliable;②,hightemperature,highpressure,temperature≤550℃,pressure≤20MPa;③,goodsealingperformance;④,uniquestructure;⑤,shellwallandtubebundlewalltemperaturedifference,tubebundlecanbefreetostretch,absorptionexpansiondifference;⑥,removable,canbecleaned;⑦,resistancetohydrogensulfidecorrosionDisadvantages:①,complexstructure,cumbersomedesign;②,heavyweight,highcost;③,moreparts,highsealingrequirements;④,maintenance,maintenancevolume.9）Ω环高压换热器

Ω环高压换热器结构由管箱、壳体、管束、Ω环等零部件组成，与普通U型管换热器结构相同，所不同的是密封垫片由Ω环代替。其原理是：工作状态下介质进入Ω环中，由于小管子承压高，故可承受压力≤32MPa，由于采用0Cr18Ni11Ti耐温可达550℃，由于操作过程中Ω环中介质存在，故垫片比压可选择为零，减少了螺栓预紧载荷而使螺柱直径减小，减少螺柱预紧时管板产生的载荷，减薄了管板的厚度，由此重量低，造价降低。9)Ωringhighpressureheatexchanger

Ωringhigh-pressureheatexchangerstructurefromthetubebox,shell,tubebundle,Ωringandothercomponents,andordinaryU-tubeheatexchangerstructureisthesame,thedifferenceisthegasketbytheΩringinstead.Theprincipleis:theworkingstateofthemediaintotheΩring,duetosmalltubepressureishigh,itcanwithstandthepressure≤32MPa,dueto0Cr18Ni11Titemperatureupto550℃,duetotheoperationprocessΩringmediumexists,Canbeselectedtozero,reducingtheboltpreloadloadleavingthestuddiameterdecreases,reducingthestudpreloadwhenthetubeplateload,thinningthethicknessofthetubeplate,whichislowweight,lowercost.优点：①、结构简单，设计简单；②、密封安全可靠；③、耐高温、高压，温度≤550℃，压力≤32MPa；④、结构独特；⑤、壳壁与管束壁温差大，可吸收热膨胀；⑥、拆卸方便，可清洗；⑦、采用流路分析法设计，传热效率提高20%以上；⑧、耐硫化氢腐蚀；⑨、重量可比螺纹锁紧环降低23%，锻件耗量少，造价节省21%；⑩、适用于8~32MPa压力的加氢换热器、合成氨换热器、化肥装置废锅换热器、巨毒介质换热器以及绝对保证无泄露的场合。缺点：Ω环加工复杂，要求较高。

advantage:①,simplestructure,simpledesign;②,sealedsafeandreliable;③,hightemperature,highpressure,temperature≤550℃,pressure≤32MPa;④,uniquestructure;⑤,shellwallandtubewalltemperaturedifference,canabsorbthermalexpansion;,Easytodisassemble,canbecleaned;⑦,theuseofflowanalysismethoddesign,heattransferefficiencyincreasedby20%;⑧,resistancetohydrogensulfidecorrosion;⑨,weightcomparabletothethreadedlockingringby23%,forgingless,twentyone%;⑩,for8~32MPapressureofthehydrogenationheatexchanger,ammoniaheatexchanger,fertilizerplantwasteheaters,gianttoxicmediaheatexchangerandabsoluteguaranteenoleakageoftheoccasion.Disadvantages:Ωringprocessingcomplex,demanding.10）、板式换热器板式换热器其结构由板片、压紧板、胶垫、支架等零部件组成，是一种传热效率高，占地面积小，重量轻、结构紧凑、维修、检修、安装较方便的换热器。板片间采用胶垫密封或焊接。10),plateheatexchangerPlateheatexchangeritsstructurebytheplate,pressingplate,pads,stentsandothercomponents,isahighheattransferefficiency,smallfootprint,lightweight,compactstructure,maintenance,repair,installationmoreconvenientHeatExchanger.Platebetweentheuseofrubbersealorwelding.（1）、板式换热器的优点①传热系数高：板式换热器具有较高的传热系数，一般约为管壳式换热器的2-5倍。主要原因是流体在管壳式换热器的壳程中流动时存在着折流板-壳体、折流板-换热管、管束-壳体之间的旁路，通过这些旁路的流体，没有充分参与换热。而板式换热器，不存在旁路，而且板片的波纹能使流体在较小的流速下产生湍流，湍流效果明显，(雷诺数约为200即为湍流)，故能获得较高的传热系数。(1),theadvantagesofplateheatexchanger

①highheattransfercoefficient:plateheatexchangerhasahighheattransfercoefficient,generallyaboutshell-and-tubeheatexchanger2-5times.Themainreasonisthatthefluidflowsintheshellsideoftheshell-and-tubeheatexchangerwiththebaffle-shell,thebaffl