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1、设备类型的选择A部分的章节总结了一些换热器的特点,对于一个已给定的程序，可能只有一个与之符合的设备类型。例如，如果精细化通过去除表面刮痕的换热器被指示出来。然而，这里也有一些没有被讨论的结晶设备,例如，外部鼓结晶器。但对于很多设备而言，存在着很多的可行性选择，对于这样的问题，应该询问供应商提供，只有这样最终选择才能够被确定。例如，流体流动成直角的管板型换热器在清洁循环系统的气体这方面很受欢迎，对于恶劣环境而言，以玻璃材质的气气换热器很受欢迎。这些部分方管管束的几排管深可以被拉出来清洗。热管换热器也用于气体与气体清洁服务。换热器的评定应该推行使用一个近似评分系数。要求显示的双管表面积的结果应该是
2、合理的。在数值下降的区域是否有专门设备 如板式换热器、或是大量的管壳单元。这些知识应该予以高度的重视，他们值得自习认真的学习。对于临界的情况而言，虽然总体项目成本和进度没有说明但是无论是从适用范围的成本,还是对有时需要支付继续运行的费用而言，都必须进行可代替的类型选择。B部分：管壳式换热器壳体的详细介绍 4.1 过程数据过程数据最初从使用者的工艺流程图中获取。使用者必须列举各个区域流体的性质，压力，温度 熔点的变化情况。换热器热设计师通常会在一个合理猜测缺失数据,但用户也可以这么做，用户应女里找到或计算流体的物理性质,除非这是常识,如空气或水。而且，应尽量使这些数据尽可能的覆盖换热器的操作范围
3、。当压力损失高于高气体压力时其密度将显著改变通过换热器将直接影响到压力下降 。用户应确保换热器设计师知道这个压力效应，如果是蒸汽冷凝的用户也，检查压力露点的影响。注释1. 限制温度为3000摄氏度2. 安装位置要高于管架3. 外部污染可以减少空气的流动和平均速度4. 取决于垫圈材料5. 适用于成本比较低非金属材料6. 密封焊接板边缘的拆卸过程比较困难7.对于直径可达1米或以上大直径压力的限制是较若的8. 适用于所有的金属9. 附注610. 只适用于非金属材料11. 适用于吕材质的维修12. 铝13. 有色金属等14. 300英尺以上的和管壳式换热器通常比较便宜15. 假设所有焊接16. 华氏4
4、000度的液体到15000度的气体17. 300英尺的地区；2000英尺18. 可应用于内部划痕区域19. 高速旋转20. 低速旋转 当独自在相同的条件下时，经过处于超临界状态，也能在液相中溶解，因此,任何试图获得混合物理性质的个体，他们的关键部件需要很好的照顾。因为这个原因物理性质分解生成的过程往往在临界区出现的4.1.2 流速和职责 不同于线性性质，用户应指定意味着温差的计算的放热曲线 ，热量释放曲线将呈现内部任何一点的温度。在焓数据不完全封闭的差距下，可以获得想要的交流效果。在该区域下的总体的热负荷指示应该在焓的变化下进行的。令人惊讶的是，这三个从为联系到一起的数据。 用户应该对温度传输
5、进行一个简短的检查，这类检查可以影响壳种类的的设计，这种情况经常发生在冷水传输中，增加冷却剂的流动和避免温度的轻微波动。4.1.3 速率 如果用户对速度有特定的要求的话，例如，在乙二醇换热器中，应该指定目标价值或价值范围的浮动，他就应该提防不必要的速度限制规定。因为，结合管束的宽度和长度等因素，这些因素可能会影响到设计的可行性，热工程师通常都考虑大多数材料对速度限制的情况下继续把它们留在设计里面。4.1.4 污染因素 污染因素是类似直觉的问题，如果用户对自己没有信心的话，他可以向同领域或相似领域的人进行请教，大体上说，速度越小污染越严重，因此污染因素倾向于成为一个自我实现的预言。用户必须考虑到
6、经济与较大的换热器不常清洗等原因,反之亦然，对一个较低的污染因素，或者是有可能从一个允许压降而言(从而允许更高的速度)。我们应该记住,污染总是失去能量,不论表面能量是否是是足够的，大型的换热器的表面往往是干净的，如果停车比较消耗财力的话，那么可以考虑化学清洗法，但如果不可行，离线化学清洗可能更快，固有的不确定性因素在对污染的影响上通常是远远大于任何中不确定性的物理特性，在某种情况下 流体的性质，温度，往往可以完全控制设计的走向。4.1.5 启动 停产和瞬态操作 除了需要指定所有可能的操作条件如他们将管辖的热设计，对机械部分的设计也是必要的，当它是使用一个固定管板或单一浮动设计时，上述因素就变的
7、更加重要，热/机械设计师能够预测最糟糕的热应力,检查一下是否能发生扩展波纹管是必要的，如果被要求，他必须做进一步的检查来确定是否能承受最糟糕条件下的压力和温度。任何换热器风头的设计是很重要的,它可以避免管道温差过大。有时在操作条件改变时和在没有出现压降和热传递的情况下可能导致速度控制更高的要求 ，由于可能导致共振 所以这种情况应该由用户自己解决 ，用户也应该考虑正在建设中的换热器的诸多的问题。4.1.6 震动 精巧的设计程序的使用是提高换热器效率的最有效方法。在某些情况下,这些都会导致钴管束共振，在几个小时内导致设计失败。HTRI机构 比如,在对进行了十分成功的研究可最近却导致问题更大的理解中
8、,我们应该采取各种各样的方法来减轻或避免它，震动会影响换热器的内部或外部，专家都会换热器设计避免自诱导性振动而做努力但是只有用户可以控制外部振动,。两种类型有些许不同的传热和压降特征的隔板,都可以效的减少污染，噪音是一个潜在的破坏问题，但是只是在气体换热器中才会发生。这很容易在设计过程中被检测出来，但是不容易解决。尽管消除震动可能增加设备的费用，但是无论是厂家还是用户都要尽量避免震动的发生。4.1.7 许用压力损失The user should consider carefully what allowable pressure loss to specify for each fluid.【
9、用户应该仔细阅读说明书对在各个部位许用应力损失的描述】 Too often an arbitrary 10 lbf/in2 is allowed.【往往任意一个10 lbf /信号是被允许的】 Heat transfer requires pressure energy, so clearly the greater the pressure drop utilized the higher the heat transfer and smaller will be the heat exchanger.【传热要求压力能量， But there is less point in specify
10、ing a high allowable pressure loss for a fluid with a high heat transfer coefficient if the other fluid has a very poor heat transfer coefficient or if heavy fouling is anticipated;【但是如果其他流体有一个很小的传热系数却缺少点允许指定一个高压力损失的具有高传热系数的流体，那么 污染将和预期的一样到来】in generation poorer the fluids heat transfer the higher s
11、hould be its allowable pressure loss.【大体上说，流体的传热能力越小，它允许的压力损失就越大】 In theory, the user should optimize the cost of power (pressure loss) with the cost of the exchanger (heat transfer).【理论上说，用户必须完善压力损失和热交换损失】 This optimization is seldom carried out because it would require several exchanger designs fo
12、r several alternative pressure losses,【这些完善工作多少是要做一些的，因为它将使一些换热器是为可选则性的压力损失而设计的】 and the optimal pressure loss would then have to be fed back to the process flow diagram;【最佳的压力损失数值最终将反馈到工艺流程图中去】this procedure would occur for every heat exchanger in the system and is clearly too slow for most project
13、s.【这个过程将在很多的系统中发生，也会使很多的项目设计变慢】 Quite often it is not optimal to take up all the allowable pressure loss for one or both fluids.【它不是最佳经常拿起所有的许用压力损失的一种或两种液体】 If one such fluid passes through several heat exchangers all to be designed by the same thermal engineer it is worthwhile specifying an overall
14、 total pressure loss allowing the thermal engineer to distribute it between exchangers to yield the lowest overall exchanger costs.【如果这样的流体通过几个热交换器的设计都是由同一热工程师值得指定的话，那么工程师有资格将许用压力成本降到最小】 Even if only one exchanger is involved it is often worthwhile to increase the allowable pressure loss above that
15、available from the process flow diagram to avoid just missing a good design.【即使仅仅只有一个换热器参与其中，那么以增加需用压力的方法来避免出差错也是值得的】 If the extra is taken up, the user, in conjunction with the thermal engineer, can decide whether the saving in surface is worth the additional pressure loss.【如果这个额外的占用,用户,结合热工程师,可以决定
16、是否保存在表面附加压力损失是值得的】4.1.8 Materials of construction【结构材料】Shell and tube heat exchangers can be made in almost any conceivable materials although some will be uneconomic in this design form.【管壳式换热器的材料几乎可以用一切可以想象的材料设计，即使这些材料有些很不经济】 The general specification of materials for corrosion resistance really o
17、ught to come from the users process engineer or materials specialist who should have more experience of the fluids than the thermal engineer.【一般规格材料的耐腐蚀性应该来自用户的工艺工程师或材料专家来鉴定】 Very often a balance between first cost and maintenance costs must be made.【往往保持成本和质量之间的平衡工作是必须要做的】 The detailed selection of
18、 materials for mechanical resistance is usually best left to the vendors mechanical engineer who will be up-to-date with construction materials,【详细的材料选择机械阻力通常最好留给供应商的机械工程师来做的】mechanical properties and trade-off against price for the final fabricated equipment. For example, it may prove advantageous
19、to specify a higher quality steel if this reduces the wall thickness and welding costs.【例如, 如果这减少壁厚和焊接成本可能有利于指定一个高质量的钢。】4.1.9 Corrosion allowance【腐蚀余度】The corrosion allowance is usually called up by the user and goes hand in hand with his materials selection.【腐蚀裕量通常是被用户和他的材料的选择共同完成的】 For example, th
20、ere is little point in specifying a corrosion allowance when an expensive corrosion resisting material has also been specified. 【例如，当一个昂贵的耐腐蚀材料被指定，指定腐蚀裕量就变得毫无意义了】Where bundle weight is a serious penalty (e.g. for offshore use) it is worth remembering that a typical corrosion allowance of in for carb
21、on steel can represent the majority of the wall thickness in low pressure service; a higher quality material with no corrosion allowance might be preferable if the higher materialscost were acceptable.【我们应该记住,一个典型的腐蚀裕量的碳钢在低压环境中能代表大多数的壁厚;一个高质量的材料腐蚀裕量可能没有高消耗的材料容易被接受】4.2 Mechanical data【机械数据】All the me
22、chanical data can, if absolutely necessary, be left to the specialist or vendor, who will make intelligent guesses in most cases, but the most informed person is usually the users process engineer.【如果必要,所有的机械数据都可以由专家或供应商提供，在大多数情况下任何一个人都可以做出明智的猜测，但最已被通知到的人通常是用户的工艺工程师】 He will assess the data and weig
23、h the consequences of its application:【他将评估数据和权衡后果】 for example, whether to ask for long thin shells which are cheaper but will require a greater lengthways clearance should the bundle need to be pulled.【是否要求更长的薄壳,更便宜的价格,但将会需要一个更大的维管束纵向间隙应。】Furthermore, if each bidder specifies his own preferred mec
24、hanical data (e.g. tube lengths, channel head and shell types) a significantly different design will probably arise from each bidder making the bids very difficult to evaluate.【如果每个投标人指定自己的首选机械数据(例如管长度、渠道的头壳类型)显著不同的设计可能会引起使每个投标人投标很难评估】 This section therefore shows ways of defining those mechanical d
25、ata best specified by the user rather than the vendor or heat transfer specialist.【本节定义的显示方式因此机械数据最好的指定的用户,而不是供应商或传热问题的专家】 With the petrochemical industries the majority of shell and tube exchangers conform to TEMA (Tubular Exchanger Manufacturers Association) standards (9).【大多数的石化行业和管壳式换热器符合(管式换热器制
26、造商协会)标准】 These standards have been developed over many years and combine most process requirements with good and economic manufacturing practice.【这些标准已经发展多年,具有良好的加工要求,结合最经济生产实践总结出来的】 There are three sets of TEMA standards: R, C and B.【有三种标准:R,C,B】 R stands for refinery practice and is the most conse
27、rvative, B is for chemical processes and C is applicable to the general commercial market.【R代表炼油厂实践是最保守的, B”是为化学过程和“C”是适用于一般的商业市场】It is common amongst refinery engineers to specify TEMA R irrespective of duty simply because it is the best.【这是常见的工程师指定提在炼油厂的R不分的责任,只是因为它是“最好的”。】 By choosing selectively
28、 from C or B standards the refinery user can however have secure yet competitive designs, but liaison with the thermal engineer is usually advisable.【通过选择有选择地从C”或“B标准炼油厂还可有用户安全竞争图案,而是联络热工程师通常是明智的。】 The TEMA standards use an alphabetical nomenclature to define the channel, shell and rear end componen
29、ts of shell and tube exchangers.【使用一个字母的标准术语来定义渠道、外壳和臀部和管壳式换热器换热元件】These may be specified in many different combinations. Figure 15 shows this TEMA designation. Each component type has its specific application; the advantages and disadvantages of each component type are listed in【这些可以被指定在许多不同的组合。图15
30、表明,该提的称号。每一个都有其特定的应用程序的组件类型,每种模式的利弊得失中列出的组件类型】4.2.1 Side selection【边缘的选择】The engineer must first judge which fluid is best suited to each side and this selection must take place before he can fully specify the correct TEMA component types.【工程师必须首先判断哪些是最适合每个流体的边缘,这样的选择必须要做 它可以充分说明正确的组件类型。】 He will ch
31、oose the sides which give him the cheapest exchanger which fulfils his needs.【他会选择最便宜的且符合自己的需要的边缘】 Table 2 lists some criteria by which he can make his. Some- times he finds his criteria clash.【表2列出一些标准,，他发现自己的一些-次标准冲突。】 For example, economics dictate that both a high pressure clean fluid and a low
32、pressure corrosive fluid should be placed on the tube side, so if heat exchange is between these he may have to run two alternative designs before finally selecting sides.【经济学要求两个高压清洁液和低压腐蚀性流体应放置在管程 所以如果换热是在这些他可能不得不做两种不同的设计,最后才会选择设计边缘】。4.2.2 T E M A type selection【T E M A类型的选择】Once the side selectio
33、n is made, the full TEMA component designation can be made. Table 3 illustrates the preferred component type for a variety of criteria; the list could no doubt be extended.4.2.3 Head selection【封头的选择】The fixed tube sheet exchanger is usually the cheapest【固定管板换热器通常是最便宜的】. If, however, a stress-relievi
34、ng device has to be used, then a U tube exchanger may prove the cheaper. 【然而，如果实用降压装置的条件下U形管式换热器可能更加便宜一些】If the bundle has to be removable, a U tube will be the cheapest.【如果管束必须是可移动的，那么U形管换热器将是最便宜的】 If the tubes must however be straight, for ease of mechanical cleaning for example, and the bundle ha
35、s to be removable, one of the floating head devices, P, S, T or W, should be specified.【但如果管必须直,为便于机械清洗为例,说明束必须是可移动的、P、S、T或W,应该被考虑使用】 Type P or W are the cheapest but are only good for low pressure fluids which are non-hazardous and non-corrosive.【P型单或W是最便宜的,但只适合低压流体无害、无腐蚀性的情况下使用】 The T type floatin
36、g head is simpler in construction than the S type, and also makes bundle removal easier,【T型浮头式换热器因其简单的类型,也使得管束的清洗更容易】, but the relatively large diameter of the head which must pass down the shell, causes an increase in shell diameter over that for an S type, and thereby allows a greater potential sh
37、ell side fluid leakage around the bundle, which in turn can cause a significant decrease in the mean temperature driving force, resulting in reduced exchanger prefer【但相对较大直径的封头,为了避免更大的潜在的壳侧管束流体四周泄漏而导致明显减低平均温度和驱动力,，应该综合考虑】4.2.4 Shell type【管壳的类型】The selection of shell type will depend on heat transfer
38、 and pressure drop considerations and may be left to the thermal rating specialist.【换热器管壳类型的选择是根据流体传递时产生的压力而定的】In general E and F type shells are naturally suited to single phase heat transfer【大体上讲单程流体传递适合选取E和F型的管壳】 because of the many different b d e arrangements possible and the relatively long fl
39、ow path available.【因为D和E型的管壳适合较长的流体传递】G and H shells are roughly equivalent to two E shells in series in respect of nearness to counter-flow, provided there is negligible leakage across the longitudinal baffle/s.【只要是在泄露可以忽略不计的情况下，G和H逆流条件下的压力相当于2倍的H型管壳】 J shells are somewhat better than E shells in t
40、his respect but not as good as G or H shells.【J型管壳在这方面也比E型的好些，但也和G或H型的差不多】 Physical leakage can be prevented by welding the G or H longitudinal baffles to the shells or to a shroud if the bundle is to be removable.【如果考虑泄露的条件时，G和H型的管束可以很好的控制泄露】 J shells have roughly one-eighth the pressure drop of an
41、 E shell of the same length and diameter.【E一样的长度和直径的J壳有大约八分之一的压力损失的外壳】The same is true of G shells provided the flow is up and down (i.e. horizontally cut transverse baffles); if it is side to side (i.e. with vertically cut transverse baffles) then the pressure loss is similar to that of the E shell
42、. H shells do not normally have any transverse baffles and the pressure drop is very significantly less than J or G shells.【如果是边对边流体的流动条件下， H壳通常都没有任何横向隔板所以对压力降的影响非常显著】4.2.5 Tube length【管长】It used to be customary for the user to specify a single standard tube length so he could standardize his layout
43、s and maintenance requirements.【官长曾经是惯例为用户指定一个单一的标准管的长度,以便他能规范换热器的布局和维护要求】 This restriction is often severely limiting to the thermal design,【对管束长度的限制经常严重影响换热器的设计】 so unless there is an overriding reason to stick with one standard length it is more economical to allow the designer a choice of severa
44、l lengths,【除非有一种很重要的理由使设计师不得不设计几种不同长度的管束】 or preferably a range of lengths, from which to optimize. Usually long thin S and T heat exchangers are cheaper for a given surface than short fat ones wall thicknesses can be less and there is less labour involved.【通常细长的管道设计比较经济，也可以减小劳动量】However in certain
45、applications, such as offshore, the usual rules for minimum equipment cost do not always apply.【然而，在某种条件下，减小开支的办法往往不切合实际】 For example, long exchangers, especially with re-movable bundles, are often very difficult to install and maintain economically because of the shortage of space offshore, and sho
46、rter, fatter, shells are then preferred despite their higher price per unit heat transfer surface.【例如，长管，可以移动的管束和难保证经济实惠，而且短的，宽的管束比较实用，尽管它们的价格很高】4.2.6 Tube pitch and layout【管束间的距离和布局】If provision must be made to mechanically clean the outside of the tubes at least a 1/4 in gap between tube outer dia
47、meters should be specified.【如果管束和管束外直径1/4的部分需要被指定的话】 Triangular layoutcan be pitched to provide cleaning lanes for each row but this leads to inefficient use of shell cross-section,【三角形的布局将是比较可行的，但是同样也会导致效率的降低】 so square or rotated square layouts are more usually specified.【所以，正方形布置经常会得到使用】 There is
48、 no theoretical limit to tube 0.d. for mechanical cleaning【对机械清洁的管道布置一般没有理论上的限制】 but the in clearance limits the tubes to a minimum of 8 in or 8 in 0.d.【但在间隙限制管至少8或8以上】 in practice.【在实际操作中】 Generally the closer layouts (triangular) and smaller tube 0.d.s and pitches yield higher heat transfer and ar
49、e therefore first preference,【小管道因为其流体传热高的原因应该优先被考虑】 but in some cases square layout will be preferred for stability reasons.【但是，在某种情况下，正方形的管束布置更加稳定】 For example, at start-up with re boilers the initial temperature driving force may be high enough to promote film boiling especially when surfaces are clean.【 例如,尤其是当表面是干净的换热器中热流体可能很高足以促进膜沸腾
