文献翻译-压力容器和它的构件

外文文献翻译压力容器和它的构件压力容器是密封容器设备，它们有着各种各样尺寸和形状。较小的压力容器直径远远小于一英寸，而较大的压力容器直径可能达到或者超过150英尺。某些是埋在地下或海洋深处，大多数是安在地上或支撑在平台上，还有一些实际上是在航空飞行器中的储槽和液压装置里。压力容器的内压，同它的尺寸以及形状一样，也是多种多样。1大气压(atm)=0.101325兆帕(MPa)=14.696磅/英寸2(psi)内压可能小到1英寸水柱静压，也可以高到300000磅/英寸2，甚至更高。对于单层结构压力容器，通常的压力范围为15到5000磅/英寸2，但是也有好多低于或者超出这个范围。ASME锅炉和压力容器规程第八部分第一节详细列出了一系列内压值，这些内压最小为15psi，最大没有限制；但是根据ASME锅炉和压力容器规程第八部分第一节，内压超过3000psi的需要进行特殊设计。压力容器的典型构件描述如下：圆柱形筒体在石油化工业中使用的压力容器在建造时主要采用圆柱形筒体这种模式。这种结构便于制作，安装以及维修经济。圆柱形筒体的厚度主要取决于内压的大小，在一些情况下，也需要考虑外加负载荷以及外压的因素。其他因素，比如热应力、不连续应力对圆柱形筒体的厚度也可能有影响。成形加工封头对于封头以及过渡区，工程师可以有多种选择。在选择具体用哪种而不用哪种时，主要考虑以下因素：成形方法，材料成本，工艺条件的要求，制造的难易程度以及空间限制。对受均匀内压封头的强度计算，由于封头和筒体连接，所以不仅需要考虑封头本身因内压引起的薄膜应力，还要考虑与圆筒相连接处的不连续应力。连接处总应力的大小与封头的几何形状和尺寸，封头与圆筒厚度的比值大小有关。但在导出封头厚度设计公式时，主要利用内压薄膜应力作为依据，而将因不连续效应产生的应力增强影响以应力增强系数的形式引入厚度计算式中。应力增强系数由有力矩理论解析导出，并辅以实验修正。一些经常使用的成形的封头是：凸形封头这种封头一般用于低压操作的压力容器，比如油箱，锅炉。当直径较小时也可用于压力很高的压力容器。具体设计及制造的详细资料见ASME锅炉和压力容器规程第八部分第一节。半球形封头通常，半球形封头的厚度取决于给定的温度和压力，而压力为同一直径和材料的圆柱形筒体压力的一半。建造材料为贵的合金，比如镍、钛或者镀镍、钛的固体时，半球形封头节约成本。假如用的是碳素钢，那么这种封头就不比法兰以及碟形封头节约成本，这主要是因为它的锻造成本很高。半球形封头通常由弓形的楔形构件拼焊或是铆接或是旋压而成。由于半球形封头比与之相接的圆柱形筒体要薄，因此，封头与筒体之间的过渡区必须逐渐变化，以减小不连续应力的影响。椭圆形封头，碟形封头（法兰和半球形）封头这些封头在压力容器中应用广泛。它们的厚度一般与相连接的筒体一样，这样能够明显的减少堆焊。椭圆形封头是由半个椭球面和短圆筒组成。直边段的作用是避免封头和圆筒的连接焊缝处出现经向曲率半径突变，以改善焊缝的受力状况。由于封头的椭球部分经线曲率变化平滑连续，故应力分布比较均匀，且椭圆形封头深度较半球形封头小得多，易于冲压成型，是目前中、低压容器中应用较多的封头之一。蝶形封头是带折边的球面封头，由半径为R的球面体、半径为r的过渡环壳和短圆筒等三部分组成。从几何形状看，蝶形封头是不连续曲面，在经线曲率半径突变的两个曲面连接处，由于曲率的较大变化而存在着较大边缘弯曲应力。该边缘弯曲应力与薄膜应力叠加，使该部分的应力远远高于其他部位，故受力状况不佳。但过渡环壳的存在降低了封头的深度，方便了成型加工，且压制蝶形封头的钢模加工简单，使蝶形封头的应用范围较为广泛。因折边区以外的区域所需的厚度小于封头的实际厚度，这样，多余的部分就可以用于这些区域的接管补强。由于好多制造厂家都能生产不同直径和厚度的这样的封头，因此价格比较低。锥形封头，折边锥形封头这些封头主要用于直立以及塔状压力容器的底部封头或者做为不同尺寸的圆柱筒体间的过渡。在锥形封头的设计中，由于锥形封头与筒体结合处的非均衡应力，在设计中，我们必须对此进行考虑。由于结构不连续，锥壳的应力分布并不理想，但其特殊的结构形式有利于固体颗粒和悬浮或粘稠液体的排放，可作为不同直径圆筒的中间过渡段，因而在中、低压容器中使用较为普遍。锥壳的强度由锥壳部分内压引起的薄膜应力和锥壳两端与圆筒连接处的边缘应力决定。锥壳设计时，应分别计算锥壳厚度、锥壳大端和小端加强段厚度。若考虑只有一种厚度组成时，则取上述各部分厚度中的最大值。由于这么高的应力存在，当锥形封头受内部压力时，ASME锅炉和压力容器规程-1限定锥形的最大顶角不能超过30。当顶角大于30时，必须进行不连续应力分析；或者采用折边锥形封头来避免结合处的非均衡应力。法兰盖，平盖板，凸形平盖压力容器的一种经常采用的封头方式是可拆卸的平头或者平盖。这种封头方式即不是同壳体一起锻造也不是焊接到壳体上，而是采用螺栓或者其他易拆卸装置来固定。平盖厚度计算式以圆平板应力分析为基础的。在理论分析时平板的周边支承被视为固支或简支，但实际上平盖与圆筒连接时，真实的支承既不是固支也不是简支，而是介于固支和简支之间。因此工程计算时常采用圆平板理论为基础的经验公式，通过系数K来体现平盖周边的支承情况，K值越小平盖周边越接近固支；反之就越接近于简支。它可能是圆形，方形，长方形或者其他形状。那些圆形扁平封头在用螺栓固定时采用的垫圈就是法兰盖。通常，用螺栓将法兰固定到压力容器的法兰上，两法兰之间加入垫圈。虽然扁平封头以及盖板可以是圆形的也可以是非圆形的，但是它们通常具有一样的厚度。开孔和接管所有的过程容器装备都需要开孔以便将物质导入及导出。对于一些压力容器，由于所盛物质较大或者一些内部部件需要经常更替，因此需要移除整个封头或者壳体的一部分以便开孔通畅。但是，对于大多数压力容器，进入和流出封头开口以及壳体的物质都是通过管口或者接管。除了这些开孔之外，我们也需要开另外一些孔，比如那些供人出入的人孔。人孔的结构形式主要决定于操作压力，操作介质和启用的频繁程度。根据使用要求，常用的人孔的结构形式有：常压平盖人孔、受压人孔、快开人孔等。另外一些开孔是在外面检查压力容器时的手孔，还有其他一些为了清洗容器以及泄放而开的孔。手孔最简单的结构形式是在接管上安装一块盲板，这种结构用于常压和低压，以及不需要经常打开的场合。需要快速启闭的手孔，应设置快速压紧装置。这些开空不一定都有接管相连。有些时候，只用盖子将其孔封住，比如人孔盖、手孔盖，它们通过螺栓或者焊接的方式与壳体固定。支座支座是用来支承容器及设备重量，并使其固定在某一位置的压力容器附件。在某些场合还受到风载荷、地震载荷等动载荷的作用。压力容器支座的结构形式很多，根据容器自身的安装形式，支座可以分为两大类：立式容器支座和卧式容器支座。立式容器有耳式支座、支承式支座、腿式支座和裙式支座等四种支座。大多数立式容器用裙座支座。利用群座支座压力容器是很经济的，因为它可以通过剪切作用来转移压力容器的荷载。它们也可以通过锚定螺栓以及垫板将压力容器的荷载转移到底座上。腿式支座压力容器一般质量轻，而且腿式支撑能够很容易提供到达压力容器底部的入口。最经济的设计就是腿部支撑和容器直接相连，荷载可以通过剪切作用直接转移。水平压力容器的支撑一般为鞍式支撑。为了防止由于壳体太薄而不能将荷载转移到鞍式支撑上，需要增加补强圈，也需要考虑热膨胀的问题。PressureVesselsandTheirComponentsPressureVesselsareleakproofcontainers,TheyaremadeinallsizesandshapesThesmalleronesmaybenolargerthanafractionofaninchindiameter，whereasthelargervesselsmaybe150ftormoreindiameterSomeareburiedinthegroundordeepintheocean；mostarepositionedonthegroundorsupportedonplatforms;andsomeactuallyarefoundinstoragetanksandhydraulicunitsinaircraft。Theinternalpressuretowhichprocessequipmentisdesignedisasvariedasthesizeandshape.Internalpressuremaybeaslowas1in.watergagepressuretoashighas300000psiormore.Theusualrangeofpressureformonoblockconstructionisabout15toabout5000psi,althoughtherearemanyvesselsdesignedforpressurebelowandabovethatrangeTheASMEBoilerandPressurecode，SectionViii，Division1，specifiesarangeofinternalpressurefrom15psiatthebottomtonoupperlimit；however，ataninternalpressureabove300psi,theASMECode,VIII-1,requiresthatspecialdesignconsiderationsmaybenecessary.TypicalcomponentsofpressurevesselsaredescribedbelowCylindricalShellCylindricalshellisveryfrequentlyusedforconstructingpressurevesselsinthepetrochemicalindustry.Itiseasytofabricateandinstallandeconomicaltomaintain.Therequiredthicknessisgenerallycontrolledbyinternalpressure，althoughinsomeinstancesappliedloadsandexternalpressurehavecontro1.OtherfactorssuchasthermalstressanddiscontinuityforcesmayalsoinfluencetherequiredthicknessFormedHeadsAlargevarietyofendclosuresandtransitionsectionsareavailabletothedesignengineer.Usingoneconfigurationversusanotherdependsonmanyfactorssuchasmethodofforming,materialcost，andspacerestriction.Subjecttouniforminternalpressureoftheheadofthestrengthcalculation,asthecylinderheadandconnected,soneedtotakeintoaccountnotonlytheheaditself,causedbyinternalpressureduetofilmstress,butalsoconnectedwiththecylinderDepartmentdiscontinuousstress.Totalstressjunctionheadsizeandthegeometricshapeandsize,andcylinderheadthicknessratioofthesize.However,thethicknessoftheheaddesignderivedformula,themainuseoftheinternalpressurebasedonthin-filmstress,andwillhaveadiscontinuouseffectofstressinordertoenhancetheimpactofstresstoenhancetheformfactorcalculationintheintroductionofthethickness.Stressenhancedbythetorquecoefficientisderivedanalytictheory,andexperimentwiththeamendment.Somefrequentlyusedformedheadsare:FlangedHeadsTheseheadsarenormallyfoundinvesselsoperatingatlowpressuresuchasgasolinetanks,andboilers.Theyarealsousedinhighpressureapplicationswherethediameterissmall.VariousdetailsfortheirdesignandconstructionaregivenbytheASME,Code,VIII一1.HemisphericalHeads.Generally，therequiredthicknessofhemisphericalheadsduetoagiventemperatureandpressureisone-halfthatofcylindricalshellswithequivalentdiameterandmaterial.Hemisphericalheadsareveryeconomicalwhenconstructedofexpensivealloyssuchasnickelandtitaniumeithersolidorclad.Incarbonsteel,however,theyarenotaseconomicalasflangedanddishedheadsbecauseofthehighcostoffabricationHemisphericalheadsarenormallyfabricatedfromsegmental“gore”sectionsorbyspinningorpressing.Becausehemisphericalheadsarethinnerthancylindricalshellstowhichtheyareattached，thetransitionareabetweentheheadsandshellmustbecontouredsoastominimizetheeffectofdiscontinuitystressEllipticalandTorispherical(FlangedandDished)HeadsTheseheadsareverypopularinpressurevessels.TheirthicknessisusuallythesameasthecylindertowhichtheyareattachedThisreducesconsiderablytheweldbuild-upEllipticalheadisashorthalf-ellipsoidandcylindercomponents.Sectionofstraightedgeistoavoidheadandthecylinderappearedweldconnectiontotheradiusofcurvature,asmutationsinordertoimprovethesituationoftheweldforce.Astheheadpartofthewarpellipsoidalsmoothcontinuouschangesincurvature,sothestressisdistributedmoreevenly,andthedepthoftheovalheadmuchsmallerthanthehemisphericalhead,easytopressmolding,iscurrentlyintheapplicationofmorelow-pressurevesselclosurethefirstone.Butterflyisthebandheadofthesphericalheadfold,fromaradiusofRofthesphericalbody,thetransitionradiusrandashortcylindricalshellringiscomposedofthreepartsandsoon.Fromthegeometry,thebutterflyisnotstraightheadsurface,mutationsinthemeridianradiusofcurvatureofthejunctionoftwosurfaces,duetothecurvatureofthelargerchangesintheedgeoftheexistenceofagreaterbendingstress.Theedgebendingstressandmembranestresssuperposition,sothatpartofthestressismuchhigherthanotherpartsofthebody,itforcespoor.However,theexistenceofthetransitionringshellreducesthedepthoftheheadtofacilitatethemoldingprocess,andthesuppressionofthesteelheadbutterflyprocessingsimple,sothatheadbutterflywiderrangeofapplications.Thus，becausetherequiredthicknessinareasawayfromtheknuckleregionislessthanthefurnishedthickness,theexcesscanbeadvantageouslyusedinreinforcingnozzlesintheseareas.Manymillscanfurnishsuchheadsinvariousdiametersandthicknessthatarecompetitiveinprice.ConicalandToriconicalHeadsTheseheadsareusedinhoppersandtowersasbottomedclosuresorastransitionsectionsbetweencylinderswithdifferentdiameters.Thecone-to-cylinderjunctionmustbeconsideredaspartoftheconedesignduetothehighunbalancedforcesatthejunctionAsaresultofthediscontinuous,conicalshellofthestressdistributionisnotideal,butthestructureoftheirparticularformofbenefitandsuspendedsolidparticlesorviscousliquidemissions,differentdiametercylinderscanbeusedasanintermediatetransitionsection,therefore,morecommonlyusedinthelow-pressurecontainers.Conicalheadsstrengthinpartfrompressurecausedbystressandconeshellmembraneandthecylinderatbothendsoftheedgejunctionstressdecision.Coneshelldesign,thecalculationshouldbethethicknessofconeshell,coneshellbigandstrengthenparagraphlittle-endthickness.Ifwearetoconsiderthethicknessofonlyonecomponent,thenchecktheabovepartofthemaximumthickness.Becauseofthesehighforces，theASMECode,-1,limitstheapexangletoamaximumof30whentheconeissubjectedtointernalpressure.Above30discontinuityanalysisisdoneoratoriconicalheadusedtoavoidtheunbalancedforcesatthejunction.BlindFlanges，CoverPlates，andFlangesOneofthemorecommontypesofclosuresforpressurevesselsistheunstayedflatheadorcover.Thismaybeeitherintegrallyformedwiththeshellorweldedtotheshell，oritmaybeattachedbyboltsorsomequick-openingdevice.Calculatethethicknessofflatcoverplatetoaround-basedstressanalysis.Inthetheoreticalanalysisofthesurroundingsupportplateisconsideredclampedorsimplysupported,butinfactcoveredwiththecylindricalflatconnection,therealisneithersupportingnorclampedsimplysupported,butbetweenclampedandsimplysupportedtheInter.Thereforeoftenusedengineeringcalculationbasedonthetheoryofaroundplateoftheempiricalformula,throughthecoefficientKtoreflectthelevelofsupporttobuildthesurroundingcircumstances,KvaluethemorethecloserXiaopingcoverclampedaround;theotherhandthemoreclosertosimplysupportedItmaybecircular，square，rectangular，orsomeothershape.ThosecircularflatheadsthatareboltedintoplaceutilizingagasketarecalledblindflangesThosecircularflatheadsthatareboltedintoplaceutilizingagasketarecalledblindflangesAlthoughflatheadsorblindflangesmaybeeithercircularornoncireular，theyusuallyhaveuniformthickness.OpeningsandNozzlesAllprocessVesselsrequireopeningstogetthecontentsinandout.Forsomevessels，wherethecontentsmaybelargeorsomeoftheinternalpartsmayneedfrequentchanging，accessismadethroughlargeopeningsinwhichtheentireheadorasectionoftheshellisremovedHowever，formostprocessvessels,thecontentsenterandexitthroughopeningsintheheadsandshelltowhichnozzlesandpipingareattached.Inadditiontotheseopeningsothersmayberequired，suchasthoseforpersonnelenteringthevesselthroughamanwayopeningManholestructuremainlydependsonoperatingpressure,operatingmediumandthefrequencyofopening.Accordingtotheuseofrequirements,commonlyusedintheformofmanholestructureareasfollows:pressurelevelmanholecover,manholecompression,fastandsoopenmanhole.OtheropeningsmaybenecessaryforinspectingtheVesselfromoutsidethroughahandholeopening，andstillothersmayberequiredforcleaningordrainingthevessel.Hand-holestructureofthesimplestformsisinstalledinablindtotakeovertheboard,suchastructurefortheatmosphericpressureandlow-voltage,anddonothaveregularopenforums.Theneedforrapidhandheadstockhole,clamping