过程装备与控制工程专业英语翻译

1、Unit19TypesofHeatExchangersHeatexchangersareequipmentprimarilyfortransferringheatbetweenhotandcoldhaveseparatepassagesforthetwostreamsandoperatemostversatileandwidelyusedexchangersaretheshell-and-tubetypesbutvariousplateandothertypesarevaluableandeconomicallycompetitiveorsuperiorinsomeothertypeswill

2、bediscussedbrieflybutmostofthespacefollowingwillbedevotedtotheshell-and-tubetypesprimarilybecauseoftheirimportancebutalsobecausetheyaremostcompletelydocumentedinthetheycanbedesignedwithadegreeofconfidencetofitintoaothertypesarelargelyproprietaryandforthemostpartmustbeprocessdesignedbytheirmanufactur

3、ers.Plate-and-FrameExchangersPlate-and-frameexchangersareassembliesofpressedcorrugatedplatesonaframe.Gasketsingroovesaroundtheperipherycontainthefluidsanddirecttheflowsintoandoutofthespacesbetweenthespacingandthepresenceofthecorrugationsresultinhighcoefficientsonbothsidesseveraltimesthoseofshell-and

4、-tubeequipmentandfoulingfactorsareaccessibilityoftheheatexchangesurfaceforcleaningmakesthemparticularlysuitableforfoulingservicesandwhereahighdegreeofsanitationisrequiredasinfoodandpharmaceuticalpressuresandtemperaturesarelimitedbythenaturesoftheavailablegasketingmaterialswithusualmaximaof300psigand

5、400F.Sinceplate-and-frameexchangersaremadebycomparativelyfewconcernsmostprocessdesigninformationaboutthemisproprietarybutmaybemadeavailabletoseriousfactorsandheattransfercoefficientsvarywiththeplatespacingandthekindsofcostsperunitofheattransferaresaidtobelowerthanforshell-and-tubestainlesssteelconst

6、ructiontheplate-and-frameconstructioncotis50%-70%thatoftheshell-and-tube.SpiralHeatExchangersInspiralheatexchangersthehotfluidentersatthecenterofthespiralelementandflowstotheperiphery;flowofthecoldliquidiscountercurrententeringattheperipheryandleavingatthetransfercoefficientsarehighonbothsidesandthe

7、reisnocorrectiontothelogmeantemperaturedifferencebecauseofthetruecountercurrent'action.Thesefactorsmayleadtosurfacerequirements20%orsolessthanthoseofshell-and-tubeexchangers.Spiraltypesgenerallymaybesuperiorwithhighlyviscousfluidsatmoderatepressures.Compact(Plate-Fin)ExchangersCompactexchangersa

8、reusedprimarilyforgastheyhavesurfacesoftheorderof1200m2/m3corrugationheightmmcorrugationthicknessmmandfindensity230-700fins/largeextendedsurfacepermitsaboutfourtimestheheattransferrateperunitvolumethatcanbeachievedwithshell-and-tubehavebeendesignedforpressiIresupto80atmorclosespacingsmilitateagainst

9、foulingcompactexchangersareusedincryogenicservicesandalsoforheatrecoveryathightemperaturesinconnectionwithgasmobileunitsasinmotorvehiclescompactexchangershavethegreatmeritsofcompactnessandlightkindofarrangementofcrossandcountercurrentflowsisfeasibleandthreeormoredifferentstreamscanbeaccommodatedinth

10、esamedropheattransferrelationsandotheraspectsofdesignarewelldocumented.AirCoolersInsuchequipmenttheprocessfluidflowsthroughfinnedtubesandcoolingairisblownacrossthemwithfans.Theeconomicsofapplicationofaircoolersfavorsservicesthatallow25-401"temperaturedifferencebetweenambientairandprocesstherang

11、eabove10Mbtu/laircoolerscanbeeconomicallycompetitivewithwatercoolerswhenwaterofadequatequalityisavailableinsuHicientamountDouble-PipeExchangersThiskindofexchangerconsistsofacentralpipesupportedwithinalargeronebypackingglands.Thestraightlengthislimitedtoamaximumofabout20ft;otherwisethecenterpipewi1ls

12、agandcausepoordistributionintheiscustomarytooperatewiththehighpressurehightemperaturehighdensityandcorrosivefluidintheinnerpipeandthelessdemandingoneintheannulus.Theinnersurfacecanbeprovidewithscrapersasindewaxingofoilsorcrystallizationfromlongitudinalfinsintheannularspacecanbeusedtoimproveheattrans

13、ferwithgasesorviscousgreaterheattransfersurfacesareneededseveraldouble-pipescanbestackedinanycombinationofseriesorparallel.Double-pipeexchangershavelargelylostouttoshell-and-tubeunitsinrecentmaybeworthconsideringinthesesituations:1. Whentheshell-sidecoefficientislessthanhalfthatofthetubeside;theannu

14、larsidecoeHicientcanbemadecomparabletothetubeside.2. Temperaturecrossesthatrequiremultishellshell-and-tubeunitscanbeavoidedbytheinherenttruecountercurrentflowindoublepipes.3. Highpressurescanbeaccommodatedmoreeconomicallyintheannulusthantheycaninalargerdiametershell.4. Atdutiesrequiringonly100200sqf

15、tofsurfacethedouble-pipemaybemoreeconomicalevenincomparisonwithoff-the-shellunts.Shell-and-TubeExchangersThistypeofexchangerswillbediscussedinthefollowingsection.(Selectedfrom:StanleyChemicalProcessEquimentButterworthPublishers1988.)WordsandExpressionsn.通道，通过a.多用途的，通用的a.专利的，私有的v.成波纹状，起波纹;corrugation

16、nh. 沟，槽i. 系数j. 密封垫片v.弄脏，堵塞;foulingfactor污垢系数n.卫生a.制药的；药物的n.;a.逆流n.翅片;v.装翅片v.妨碍，起作用a.冷冻的，低温的n.恢复，回收，再生n.填料盖，密封套v.下垂，下沉n.环状空间;annulara环形的.v.脱蜡n.结晶，结晶体n.堆积，烟囱a.内在的，固有的v.调节，适度，容纳Unit19换热器的种类换热器起初是为了在热流和冷流中传热。对两种冷热流体一般有单独的通道，一般是连续性操作。最通用的换热器是壳管式换热器。但是不同种类板式和其他形式是有价值的和经济竞争能力。虽然一些其他形式也被讨论，但是接下来大部分都在讨论壳管式的。

17、起初是因为它们的重要性也是应为他们在文献中由较完整的记载。因袭它们可以以一种适当过程的准确标准被设计。其他类型的基本上市带有专利性的，并且多数必须有他们的制造厂来进行工艺设计。板框式换热器板框式换热器是在一个结构上压紧波纹板的装配体。围在边缘的够槽中密封垫片含有液体，并且控制板间液体的流入与流出空间。紧密的缝隙和波纹的板框换热器，在两侧的上部达到了管壳式换热器的几倍，而且板框式换热器的污垢系数较小。换热表面对于清扫的容易性德尔板框式换热器特别适用于污垢设备，也适用于卫生要求较高的行业，比如制药和食品工业，受到可能的垫圈式的密封材料性能的影响，一般最高压力值为300psig，最高温度为4000F

18、.。由于较少气液制造板框式换热器，大多数关于板框式换热器的工艺设计资料到有专利性，但也许提供给负责的工程师。摩擦饮食和热传递系数碎着班的空间和波纹的种类变化。泵花费的每个热传递单元比壳管式设备低。用纯钢制造板框式换热器的费用是管壳式的5070%。螺旋型换热器在螺旋形换热设备中，热流进入螺旋单元的中心，并且流到边缘。冷流体是逆流的。在边缘进入并在中心位置流出。在两边热传递系数较高。由于真正的逆流形式没有原来形式的温差，这些因素可能导致表面要求20%或更小的壳管式换热器。螺线形式对于中等压力的高粘性流体比较适合。翘片式换热器翘片式换热器首先被应用在油气设备中。典型的翘片式换热器在单位体积上有120

19、0平方米的表面积，翘片高度11.8mm翘片的厚度是0.20.6mm,片的密度是230700片每米。在单位体积上翘片式换热器是壳管式换热器的4倍。翘片式换热器的操作压力设计为80atm。因为翘片式换热器之间的间距小，所以不适合易堵塞的设备。从商业上说，翘片式换热器适用于低温设备，也是用于与汽轮机相关的高温恢复设备。对于动力设备来说，比如在有发动机的交通工具中，翘片式换热器有结构紧凑和质量轻的优点。错流和逆流的任何排列形式都是可行的，并且在同一设备中可以安排三种或三种以上的流束，压力下降、热交换关系的设计其他方面被很好的记载。空气冷却器这种设备是指由流体流过翘片式的管道，并且有风扇冷却的空气通过管

20、道。考虑空气冷却器的经济性，可以允许流体与周围空气和出口的温差为25400F。荡船热效率超过每小时1千万英热时单位时，空气冷却器与水满足要求且供应量充足时，与水冷在经济上不分上下。套管式换热器套管式换热器是由一个尺寸比较大的和中间一个尺寸比较小的中央管通过塑料密封套连接而成。直线长度被限制在20ft，否则中心管将下沉并且使环面的分配空间较小。一般情况，高温、高压、高密度和腐蚀性的液体放在内管上，较小要求的液体被放在外侧管子上。当在处理石油脱蜡和液体结晶时，内表面上应该提供刮刀。在环状的空间上，轴向翘片可以改善气体和粘性流体的热交换效率。假如应用较大的热交换表面。套管可以排布堆积起来，也可以应用

21、平行方式。这些套管式换热器已经逐渐被管壳式换热器所取代。在以下情况下，是值得考虑的。（ 1） 当壳侧系数比管侧系数一样小时，这时壳侧系数可以与管侧相比了（ 2） 我们可以在套管式换热器中采用真正意义上的逆流来代替，因为温度较高需要多个套管单元。（ 3） 在与大直径壳体相比，我们的环装空间是使用较高压力来满足经济性能（ 4） 而与开放式壳体换热器相比，当我们的换热器表面仅仅是100200sqft时，我们套管式换热器有较高的经济性壳管换热器这种换热器将在以后几章讨论。Notes 本句可译为：“其他类型基本上是带有专利性的，并且多数必须由它们的制造厂进行工艺设计”。 本句可译为：“由于较少企业制造板

22、框式换热器，大多数关于板框式换热器的工艺设计资料是带有专利性的，但也许可以提供给负责任的工程师”。“NisavailabletoM"，M可以得到N.句中的“concers”作企业，财团解释。 本句可译为：“错流和逆流的任何排列形式都是可行的，并且在同一设备中可以安排三种或多种流束”。 本句可译为：“当传热速率超过每小时1千万英热单位时，空气冷却器与水质满足要求且供应量充足时水冷却器在经济性上不相上下”。Exercises1. Whattypeofheatexchangersismostwidelyusedinindustries2. Inwhatsituationsmaythedou

23、ble-pipeexchangersbeused3. UsingthefollowingphrasestomakeEnglishsentences:(1) beavailableto(2)befeasible(3)becompetitivewith(4) militateagainst(5)inconnectionwith4. PutthefollowingphrasesintoChinese:122(1) Plate-and-frameexchangers(2)spiralheatexchangers(3) plate-finexchangers(4)aircoolers(5)double-

24、pipeexchangers(6)shell-and-tubeexchangersReadingMaterial19Shell-and-TubeHeatExchangersShell-and-tubeexchangersaremadeupofanumberoftubesinparallelandseriesthroughwhichonefluidtravelsandenclosedinashellthroughwhichtheotherfluidisconducted.Theshellsideisprovidedwithanumberofbafflestopromotehighvelociti

25、esandlargelymoreefficientcrossflowontheoutsidesofthetubes.TheversatilityandwidespreaduseofthisequipmenthasgivenrisetothedevelopmentofindustrywidestandardsofshichthemostwidelyobservedaretheTEMAstandards.Atypicalshell-and-tubeexchangerispresentedonFig.4.3.Shell-and-tubeexchangerI-Shelh;2-Shellcoveq;3-

26、Shellchannel;4-shellcoverendflange;5-Shellnozzle6-Floatingtuesheet;7-Floatinghead;8-Floatingheadflange;9-Channelpartition;10-Stationarytubesheet;11-Channel;12-Channelcover;13-Channelnozzle;14-Tierodsandspacers;15-Transversebafflesorsupportplates;16-Impingementbaffle;17-Ventconnection;18-Drainconnect

27、ion;19-Testconnection;20-Supportsaddles;21-Liftingring;Bafflepitch,ordistancebetweenbaffles,normallyis0.21.0timestheinsidediameteroftheshell.Boththeheattransfercoefficientandthepressuredropdependonthebafflepitch,sothatisselectionispartoftheoptimizationoftheheatexchanger.Thewindowofsegmentalbafflesco

28、mmonlyisabort25%,butitalsoisaparameterinthethermal-hydraulicdesignoftheequipment.Inordertosimplifyexternalpiping,exchangersmostlyarebuiltwithevennumberoftubepasses.Partitioningreducesthenumberofthetubesthatcanbeaccommodatedinashellofagivensize.Squaretubepitchincomparisonwithtriangularpitchaccommodat

29、esfewertubesbutispreferablewhentheshellsidemustbecleanedbybrushing.Twoshellpassesareobtainedwithalongitudinalbaffle.Morethantwoshellpassesnormallyarenotprovidedinasingleshell,brta48arrangementisthermallyequivalenttotwo24shellsinseries,andhighercombinationsisobtainablewithshell-and-tubeexchangers,inp

30、articular: Singlephase,condensationorboilingcanbeaccommodatedineitherthetubesortheshell,inverticalorhorizontalpositions. Pressurerangeandpressuredroparevirtuallyunlimited,andcanbeadjustedindependentlyforthetwofluids. Thermalstressescanbeaccommodatedinexpensively. Agreatvarietyofmaterialsofconstructi

31、oncanbeusedandmaybedifferentfortheshellandtubes. Extendedsurfacesforimprovedheattransfercanbeusedoneitherside. Agreatrangeofthermalcapacitiesisobtainable. Theequipmentisreadilydismantledforcleaningorrepair.Severalconsiderationsmayinfluencewhichfluidgoesonthetubesideortheshellside.Thetubesideisprefer

32、ableforthefluidthathasthehigherpressure,orthehighertemperatureorismorecorrosive.Thetubesideislesslikelytoleakexpensiveorhazardousfluidsandismoreeasilycleaned.Bothpressuredropandlaminarheattransfercanbepredictedmoreaccuratelyforthetubeside.Accordingly,whenthesefactorsarecritical,thetubesideshouldbese

33、lectedforthatfluid.TurbulentflowisobtainedatlowerReynoldsnumbersontheshellside,sothatthefluidwiththelowermassflowpreferablygoesonthatside.HighReynoldsnumbersareobtainedbymultipassingthetubeside,butataprice.Asubstantialnumberofparametersisinvolvedinthedesignofashell-and-tubeheatexchangerforspecifiedt

34、hermalandhydraulicconditionsanddesiredeconomics,including:tubediameter,thickness,length,numberofpasses,pitch,squareortriangular;sizeofshell,numberofshellbaffles,baffletype,bafflewindows,bafflespacing,andsoon.Forevenamodestsizeddesignprogram,itisestimatedthat40separatelogicaldesignsmayneedtobemadewhi

35、chleadto240=differentpathsthroughthelogic.Sincesuchanumberisentirelytoolargefornormalcomputerprocess,theproblemmustbesimplifiedwithsomearbitrarydecisionsbasedonasmuchcurrentpracticeaspossible.1988.)(Selectedfrom:Stanley.ChemicalProcessPublishersWordsandExpressions1. bafflen.折流板，挡板2. terminologyn.术语，专业用名词3. pitchn.间距，位置4. optimizationn.最佳化，优选法5. segmentala.部分的，扇形的6. partitionv.;n.隔开，分割冷凝，凝聚 分解，除去，拆开，拆卸7. condensatio