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（一）Shell and tube heat exchanger design procedure 管壳式换热器设计步骤
1.Identify service(proce unit, heat exchanger type as cooler, reboiler, condenser, chiller, steam generator etc.).定义服务：（工艺设备，换热器如：冷却器，再沸器，冷凝器，深冷器，蒸汽发生器等等）2.Identify heating medium and cooling medium;定义加热介质和冷却介质
3.Check hot / cold side is heat balance or not? if not, how much differ? le than or equal to 5%, reminder proce guy and continue to design;more than 5%, reject proce datasheet and stop.校核热/冷侧是否热平衡？如果不是的话，相差多少？小于等于5%时，工艺计算提示继续设计，超过5%，返回并结束设计。
4.Is temperature cro? How many “e” shells in series required?(Normally 2 shells in series can be adapt to about 10 degree temperature cro.)温度交叉？要求多少E型壳体？（通常双壳程适用于10℃的温度交叉）
5.Select the TEMA type(normally project should have a heat exchanger thermal design guide.)选择TEMA标准（通常，每一个换热器都有热力设计指南）
6.Select tube material and shell material(if not specified by material engineer guy).选择管程材料和壳程材料（如果不是材料工程师具体指定的）
7.Select tube length(normally 16' or 20' for horizontal exchangers;10' or 12' for vertical thermosyphon reboilers.)选择换热管长度（通常水平布置换热器用16’或者20’，垂直热虹吸再沸器用10’和12’）8.Select the start shell id, number of tubes and number of tube paes.选择壳体内径，换热管数量和管程数 9.Select baffle type, orientation, cut and spacing 选择折流板形式，方向，切口和间距 10.Determine nozzle size and location 选择接管尺寸和位置
11.First try, adjust design parameters 首次调试，调整设计参数
（二）Topic: thermal design by HTRI 主题：HTRI热力设计
Design parameters(suitable to HTRI)设计参数（适用于HTRI）
Shell I.D, Tube length, Tube OD, Tube pitch, Tube count, Tube pa, Baffle type, Cut and spacing, Flow rate of hot & cold fluid
壳程内径，管长，管外径，管间距，管数量，管程数，折流板类型、切口形式以及间距，冷热流体的流速。
Different person runs, get different results.（运算结果因人而异）a)Different background 不同的背景材料 b)Personnel conscious 个人意识
c)How much know about HTRI programs 对HTRI的认知深浅 d)Confidence level 把握程度 e)Mistakes 犯错
HTRI Case Mode: Rating, Simulation, Design HTRI案例、模拟、设计 Shell Geometry: Type 壳程几何结构
Baffle Geometry: Type-none, single segmental（单弓形）, double segmental（双弓形）, NTIW(no tube in window)窗口不排管, Rod折流杆, Helical螺旋折流板, Double Helix双螺旋, EM full 蛋框式全折流板, EM Segmental 蛋框式部分折流板.Orientation方向: Horizontal, vertical, 45 degree 水平、竖直、45°倾斜 Cut-min.max.Spacing-inlet, outlet, min, max.Tube Geometry: low fin, longitudinal fin, bare tube, win land GEWAKS.低翅片、纵向肋片、光管、维兰德GEWA-KS管
Fin Geometry: See databank or manual input;见数据库和操作手册
Reboiler Data: Thermosiphon Reboiler, kettle type reboiler, required liquid head, inlet preure location, reboiler piping setting.重沸器数据：热虹吸重沸器，釜式重沸器、所需液柱压力、进口压力，重沸器配管 Tube pa, Pa lane Baffle Geometry: Double Segmental, over lap tube rows;Variable baffle-up to 5 different spacing;折流板结构：双弓形，Clearance: Block A, F, E stream;setting seal strip/ rod;bundle-to-shell clearance, baffle-to-tube clearance, nozzle inlet / outle height;间隙：A,F,E流路;设计密封条和密封杆；管束和壳体间的间隙，折流板和换热管的间隙，进出口接管高度:
Nozzle: inlet / outlet & vent/drain 接管：进出口和排气管、排水管 Distribution Belts Impingement device: rod / plate 防冲装置：防冲杆/防冲板
Optional: Double Tubesheet, Expansion Joint, Floating Head Support Plate, Full Support at U-bend, inlet / outlet partial support;双管板、膨胀节、浮头式换热器支撑板、U形管弯管处加全支撑，管子进口/出口段加部分支撑。
3（三-1）Comply with ASME code during early design stages 起步设计阶段遵从ASME标准
Compliance with the ASME Code during the thermal design phase aures that the final shell-and-tube heat-exchanger design is accurate and minimizes lost time and labor for making revisions later.热力设计阶段遵从ASME标准能确保管壳式换热器的最终设计的准确性，将浪费的时间缩至最低，为后期版本的修改减少工作强度。
The claical division between thermal design engineers and mechanical design engineers is becoming blurred.Tools are now available that enable the design engineer to perform an integrated thermal/mechanical design calculation.热工计算工程师和设备设计工程师之间传统的划分正在变得模糊。现在软件的可行性使得设计工程师解决热力和设备设计整套的计算。Traditionally, the proce engineer would design the heat exchanger to meet proce requirements and then transfer the basic exchanger geometry to a mechanical engineer for detailed mechanical design.The mechanical engineer would apply construction code rules, such as those established by ASME and by the Tubular Exchanger Manufacturers Aociation(TEMA), and check for overstre conditions caused by thermal and other strees(longitudinal, compreive, etc.).In many cases, a change was initiated by the mechanical engineer that would affect the thermal design.If the mechanical engineer recognized this, the change would be sent back to the proce engineer for review.This “work-in progre” transfer would be repeated several times, wasting time and money with each transfer.一般来讲，工艺工程师设计换热器来满足工艺需要，然后提出基本的换热器结构给设备工程师，设备工程师完成详细的设备设计。设备工程师将按照结构标准，比如那些已经实施的ASME标准和TEMA标准。校核由于热应力以及其他应力（轴向应力、压缩应力等等）。在许多例子中。设备工程师的一个变动将影响到热力设计。如果设备工程师认识到这点，这个变动得反馈给工艺工程师以求审核。这样的工作过程的流转将会被重复好几次。每一次流转都会费时费钱。
With recent improvements in computerized design tools, we now have the ability to do a “once-through” thermal and mechanical design, resulting in significant cost savings.A project engineer with the appropriate tools can now oversee the design proce from thermal design to mechanical design without costly back-and-forth movement of data.This procedure can also be extended to vendors, thereby saving a significant amount of time sending, receiving, checking, and re-sending design data.随着进来设计工具计算机化的改进，我们现在有能力做一个一次性就能通过的热力和机械计算。而且成本显著的节约。恰当的利用工具项目工程师能够对热力设计到机械设计整个流程进行监督，而不会造成高昂代价的前后反反复复的数据变动。这个程序也可以扩展到供应商，从而节省大量用来发送，接收，检查的时间以及设计修改数据发送的时间。
Shell-and-tube equipment design 管壳式换热器的设计
A succeful shell-and-tube heat-exchanger design includes many aspects: thermal design, mechanical design, external piping loads, seismic loads, wind loads, support design, cost estimation, drawing generation, and so on.The ASME Code(as well as other construction codes, such as AD-Merkblatter [Germany], Code Francais de Construction des Appareils a Preion(CODAP)[France], and BS 5500 [U.K])plays an important role in the completion of many of these analyses.一个成功的管壳式换热器设计包括许多方面：热力设计。机械设计，外部的管道配置，地震载荷，风载荷，支座设计，造价估计，生成图纸等等。ASME标准（和其他的建造标准一样，比如德国的AD-Merkblatter 标准，法国的CODAP标准，英国的BS 5500)在许多完成分析中起着重要的作用)
Many studies have been conducted on the thermal optimization of heat exchangers.For instance, Stein Meyer suggests that there are over 500 publications on the subject of heat-exchanger optimization(1).However, true optimization not only encompaes the thermal design portion, but also mechanical design.In selecting an optimum heat exchanger design for a particular service, many iues need to be considered, including the following.: e3 {.w+!n9 S' h 对换热器的换热优化已经做了很多的研究，比如Stein Meyer 说已经有超过500部以换热器优化为主题的出版物。然而，真正的优化不仅包括热力设计部分，还包括了机械设计。在为一个特定条件选择一个最佳的换热器设计，很多问题需要考虑，包括以下内容：
Geometry: The best configuration for a given proce is sometimes difficult to select.For example, a distillation column reboiler can have either forced circulation(using a pump)or natural circulation(where the fluid density is the driving force), and within these two categories, the reboiler can be horizontal or vertical, with or without a removable bundle, and so on.结构:给定工艺的最佳结构置，有时难以选用。例如，蒸馏塔再沸器要么强制循环（用泵）要么自然循环（流体的密度是动力），并在这两者之中，再沸器可水平也可垂直，还有和蒸馏塔是可拆卸装配还是固定装配，等等。
Veel shapes also contribute significantly to the cost of the unit.In general, flat components(e.g., a flat head)will be several times thicker than curved ones(e.g., a formed head).Therefore, unle there are reasons to specify flat components(such as for easier acce to internals), it is always better to specify curved ones(2).容器的形状也有助于控制成本。在一般情况下，平面部件（例如，一个平封头）比弧形的（例如，成型封头）要厚数倍。因此，除非有原因才使用平面部件（如更容易地进入到设备内部），弧形封头一直是更好的选择。
Maintenance: It is important to consider cost reductions throughout the life of the equipment.For example, ease of maintenance is very important in high-fouling environments where frequent cleaning is required.Fouling can often be minimized by maintaining high fluid velocities and avoiding stagnant fluid regimes.Other considerations include the selection of the most appropriate method for cleaning(chemical or mechanical, off-line or on-line, etc.)and establishing whether the tube bundle needs to be removed to be properly cleaned(3).维护：考虑整个设备的使用寿命来降低造价那是相当重要的。比如，在高污染介质中频繁清洗对于维护是非常重要的的。污垢往往可以最小化而能保持高流速和避免流体停滞的现象。其他考虑因素包括选择最合适的方法进行清洗（化学或机械，停车状态或正常运行状态，等等），并确定管束有无必要抽出清洗。Vibration: Vibration or exceive velocity can occur even in an exchanger that has been designed for optimum operation and maintainability.In many cases, the type of baffling or baffle spacing(or both), tube layout, or tube dimensions may have to be modified to avoid these problems.For example, using more longitudinal flow will decrease fluid velocities and reduce the probability of vibration.These changes require redesigning the unit to establish the optimum proce design that also avoids these problems.振动：在已完成按照最优化操作和维护设计的换热器中可能会出现振动或者过高的流速，在许多情况下，只需改动折流板或者折流板间距（或两者），换热管排布，或者管间距的形式就能避免这些问题。例如更多的纵向流动，降低流速，就能减少振动的可能性。这些改变，需要重新设计以确定最佳的工艺设计从而避免这些问题。
Erosion-corrosion: Erosion-corrosion can decrease the equipment's operational life.One method to avoid exceive erosion is to maintain fluid velocities below an allowable maximum.Erosion effects are also important in corrosion chemistry.Changes in oxygen concentration, as well as the destruction of protective layers, are other consequences of erosion attack(4).冲刷腐蚀：冲刷腐蚀会降低设备的使用寿命。避免过度侵蚀的方法之一就是保持低于允许的最大流速。
Suitable materials of construction and protective covers can be selected to minimize corrosion attack and reduce costs.For example, cost savings of over 50% have been realized using alloy-clad materials rather than solid alloys(5).In addition, care should be taken to avoid exceive thermal strees caused by welding metals with different thermal 合适的结构材料和保护层能将腐蚀最小化并能降低成本。比如，用合金衬里就比全合金省50%以上的资金。另外，由于金属焊接温度的差异导致热应力必须得重视
6（三-2）Mechanical design the ASME Code 机械设计ASME标准
The ASME Code was established by the American Society of Mechanical Engineers at the turn of the century to standardize boiler design because of frequent boiler explosions.The current edition is the 1995 ASME Boiler and Preure Veel Code.The section of interest to shell-and-tube heat-exchanger designers is Section VIII, Rules for Construction of Preure Veels, Division 1.This is the primary standard used for veel mechanical design in the United States.ASME标准是在本世纪初由于频繁的锅炉爆炸事件发生而由美国机械工程师协会建立的。当前的版本是1995年的ASME锅炉压力容器准则。感兴趣的管壳式换热器部分是第VIII卷-压力容器监造规程第一分册。在美国，这是压力容器设计最主要的标准。
What can go wrong? 会出什么错？
Performing mechanical design independently from thermal design can result in an exchanger that does not perform as expected.Two main types of problems can occur:
脱离了热力设计的机械设计可能会导致换热器的性能达不到预期效果。两个最主要的问题可能会发生：
Changes initiated by mechanical design that require adjustment to thermal design;and mechanical design criteria that can significantly increase cost.机械设计的改变可能会需要重新调整热力设计，机械设计的准则能明显的增加造价。Changes that require more changes 一方的改动需要另一方更多的改动
Changes made by the mechanical designer that neceitate thermal design adjustments include: 机械设计者得变动需要热力设计有如下调整：
1.Tubes that will not fit into the stated diameter.This can occur because(a)a minimum tolerance is required for mechanical construction(for example, for TEMA T or S rear head types),(b)a high tube side design preure reduces the available outer tube limit(OTL)calculated during the thermal design,(c)the inside diameter was used for thermal design but an outside diameter criterion had to be used for mechanical design due to the product form(e.g., pipe vs.plate), or(d)the outside diameter was used for thermal design and the resulting wall thickne calculated in the mechanical design reduces the number of tubes that will fit in the shell.1.换热管原先的管径不再适合。这可能是因为：
a）机械结构需要最小的公差。（比如，TEMA标准的浮头式换热器“T”或者“S”型后端管箱）b)热力设计中，一个高设计压力的管程会减少已计算好的最外侧布管限制数量。
c)热力设计一般用内径，而机械设计由于产品形式（如用板材卷制的管道）一般用外径准则。d）热力设计中用外径计算时，机械设计中计算壁厚的结果会减少换热管的数量从而适合壳体。
2.Additional tube supports added to stiffen the rear end of bundles with floating heads or U-tubes 额外增加的换热管支撑能增强浮头式或U型管尾端的强度
3.Shell side nozzles that are moved due to construction requirements, such as mechanical reinforcement rules, hub flanges clearances, etc.由于结构需要壳程接管要被移动，比如机械加固，hub flanges clearances，等等
4.Mechanical design changes, such as a different exchanger type, different materials, closer baffle spacing, or different tube dimensions, to accommodate the differential expansion of the shell and tubes in fixed-tubesheet exchangers.4.改变机械设计以满足固定管板式换热器壳体和换热管的膨胀差，诸如不同的换热器形式，不同的材料，减小折流板间距或者不同的管径
5.Mechanical design changes to reduce exceive thermal strees in one component due to the large temperature gradients, for example, the tubesheet in multipa units.比如，多管程换热器中管板，由于大的温度梯度，在其中通过改变机械设计来减少过分的热应力。
Tubes will not fitO.D.vs.I.D.If the product form is pipe but the unit was thermally designed to use plate, the number of tubes may not fit.The mechanical portion of the design software will calculate the required wall thickne.If this wall thickne is significant and the design proceeds inward from the outside diameter, the resulting inside diameter may not be large enough to contain the required internals.This problem can also happen if the thermal design is based on the veel outside diameter.The channel(tube)side may also control the tube layout, particularly when the preure differential between the tubeside and the shellside is considerable.Special tubesheet construction, such as stub ends for butt welds, will add additional clearance that can also reduce the area available for tubes.换热管将不适用于-外径相对于内径。如果壳体的生产形式以标准管道来设计，但是该装置却热力设计时使用板材卷制时。计算软件的机械设计部分算出所需壳体壁厚，如果壁厚比较大，而且设计步骤是从外径再确定内径的话。所得的壳体内径将不满足所需的内部空间。如果热力设计是基于容器外径那么问题就会发生。尤其是当管程和课程的压力差比较大时，管程可能会约束换热管的排管布置。特别是管板结构，比如，将会多出额外的间隙这样也会降低布管区域的可利用性。
Additional tube supports.In typical removable-bundle designs, the tubes need to be rigid enough to avoid sagging.One way to stiffen the bundle is to add support plates near the rear head of a floating head or U-tube exchanger(Figure 2).In some instances, these additional supports render the tube surface partially ineffective in this area.The same situation arises in U-tube construction when the baffle span is greater than recommended to avoid vibration--additional supports are added at the rear of the U-tube bundle to reduce the unsupported tube span.Care should be taken to make the tube surface in these areas as effective as poible without unreasonable preure drop penalties.额外的管支撑，在典型的可移动管束设计中，换热管需要加固措施以避免管子下垂，加固管束的方法之一就是在浮头式或者U型管式换热器尾部增加支撑板。在某些情况下，额外的支撑会使换热管和支撑板接触的表面部分会换热失效，在同样的情况下，U型管换热器中当折流板间距大于推荐值时可以避免振动---在U型管束的弯管处增加额外的支撑能降低无支撑跨距。还要对换热管表面采取一定的有效措施以避免不合理的压力降损失。
Incorrect nozzle location.Another potential problem involves the position of the shell nozzles relative to the baffles.The proper nozzle position with respect to the impingement plate and the first baffle is illustrated in Figure 3a.错误的接管位置。另一个潜在的问题就是壳体接管相对于折流板的位置，图3a所示为接管相对于防冲板和第一块折流板的恰当位置。
A reinforcing pad is required(discued later), the shell inlet nozzle may be shifted(to accommodate the required clearance between the pad and the tubesheet), as shown in Figure 3b.With the nozzle in this position, the inlet flow is split by the first baffle and much of the flow mies the impingement plate, resulting in severe fluid bypa and potential tube erosion.This can be avoided by moving the impingement plate and first baffle to the right so they are positioned correctly relative to the impingement plate and baffle.如果需要补强圈（后续讨论），正如图3b所示可能会改变壳体的进口管位置(以调整管板和补强圈之间的距离)。介于接管所处位置，进口流体被第一块折流板后分成多股流体再加上大量的流体不通过防冲板而直接冲刷管束，导致产生很多旁路流体并且存在潜在的换热管冲刷腐蚀。通过移动防冲板位置和第一块折流板的位置便能避免这些问题。
Changes in mechanical design.If design changes are made during the mechanical design phase, a thermal re-evaluation of the exchanger may be required.For example, a common solution to solve exceive tube compreive stre in fixed tubesheet exchangers is to add more baffles.If such action were taken, the previous thermal design results would be incorrect.机械设计上的改变。如果在机械设计阶段时设计出现变更，那么换热器的热效率需要被重新评估。比如，固定管板换热器过分的压缩应力常用方法是增加折流板数量。一旦采取这些措施，原先的热力设计将会不再准确
Changes to reduce thermally induced strees.All strees in a veel must be within the maximum allowed by code.In a heat exchanger, since both sides are at different temperatures, there will always be thermal strees.Depending on the temperature gradient, geometry, materials of construction, and other factors, these strees can be significant.Mechanical changes designed to reduce thermally induced strees can severely impact thermal performance.为降低热应力做变动，容器内所有的应力必须在标准允许的最大范围内。在换热器中，管程和壳程有温度差，所以一直有热应力。根据温度梯度，几何形状，结构材料以及其他因数，这些应力相当大，为降低热应力而做的机械设计变更可能大幅的影响热性能。
In the simplest case, an expansion joint needs to be added to a fixed-tubesheet exchanger to absorb the exceive thermal strees.If the strees are still too high after adding an expansion joint, a change in geometry is required.在最简单的情况下，固定管板式换热器需加一个膨胀节来吸收过多的热应力，如果在加了膨胀节后应力仍然很大，那么就需要改变几何结构了。
A floating head or U-tube construction may be acceptable if a fixed-tubesheet unit cannot be used.Exchanger designs that serve dual purposes can sometimes be used.For example, if a fixed-tubesheet kettle is going to be used and the stre analysis recommends an expansion joint, the kettle itself can serve as an expansion joint.Clearly, dual-purpose construction lowers capital costs.Exceive thermal strees can also occur in multi-tube exchangers where the tubesheet is subject to large temperature gradients from pa to pa.In these cases, proper gasket selection is important to avoid potential leakage due to metal distortion.如果固定管板式不能使用，那么可以用浮头式和U型管式的换热器。有时要设计双重作用的换热器。比如，使用釜式固定管板式换热器并且应力分析建议使用膨胀节，釜体本身可充当膨胀节。所以双重作用的结构形式能降低成本资金。在多管程换热器中，由于流体的流进流出管板存在很大的温度梯度，继而产生过度的热应力。在这些情况下，由于金属的变形，为了避免潜在的泄露而选择恰当的垫片形式是非常重要的。
10（三-3）Mechanical criteria that affect cost 机械标准影响了成本
Mechanical design criteria that can significantly affect the cost of an exchanger include: 机械设计标准显著的影响换热器成本包括如下： 1.Equipment designed under “lethal service” Code rules.1.致命错误下设计的设备
2.Special materials of construction or construction features required to accommodate very low or very high design temperatures.2．很低或者很高的设计温度需要特殊的结构材料和结构形式
3.Supports that need to be redesigned because of exceive shell or head buckling due to support loads.因为支承载荷引起壳体和管箱过度位移，需要重新设计支撑形式
Lethal service: If a veel's contents could kill, it is the user's responsibility to provide a safe design.The ASME Code provides rules to make veels safer under the label “lethal service.” 危险性使用：如果容器的介质是致命性的，提供安全的设计服务是对用户的责任。在―危险性使用‖标签下，ASME标准为容器提供更安全的规章。
Although many substances are harmful if allowed to escape the veel boundaries, the Code defines lethal substances as poisonous gases or liquids that are dangerous to life when inhaled(e.g., hydrocyanic acid, carbonyl chloride, cyanogen ,xylyl bromide, and others(8)).However, many other procees could easily qualify as lethal if somehow the veel contents were allowed to escape.The decision then becomes one of added cost vs.additional safety features.The equipment user has the responsibility of labeling the equipment as “lethal service.”
尽管许多物质具有有害性，即使允许不纳入容器划类，但是对于吸入这些有毒的气体或液体后对人产生危害的（比如氢氰酸、羰基氯化物、光气、甲苄基溴等），规程把其定义为致命性物质。如果有时容器介质允许不划类，但是其他许多因素很容易使其被认为是致命性的。然后就是决定到底是增加制造成本还是额外安全附件。设备用户有责任在设备上标示―危险性使用‖
Lethal service designs have the following requirements: veel butt welds must be fully radio graphed;
使用具有危险性的设备必须遵循以下要求；容器的对接焊缝必须100%RT。
Body flanges must be of the hub type;carbon steel material must be post-weld heat-treated;and additional rules concerning tubes and product forms(such as seamle rather than welded tubes [the latter require further testing])must be adhered to.凸面法兰必须是带颈法兰形式；碳钢必须做焊后热处理；以及必须遵守换热管产品形式的附加规则（例如是无缝钢管而不是焊接管[后者需要复检]）。
Full radiography means to x-ray every butt-weld seam of the veel to verify the quality of the welds.Figure 4 illustrates a hub-type flange with a butt-weld at the end.In contrast, a simple ring flange is shown in Figure 5.Note that the simple ring flange, although more economical, cannot be used in lethal service because of the lack of a butt weld.Welds of the type shown in Figure 5 are referred to as fillet welds, and they cannot be x-rayed in a meaningful way.100%RT能确保每一道对接焊缝的质量。图4所示为一带颈对焊法兰。相反，如图5所示一个简单的法兰盘，尽管更加便宜，但是由于焊缝不能对接所以不能用在危险性设备上。图5所示的焊缝为角焊缝，角焊缝不易做X射线探伤。
Low-temperature service: In low-temperature service(typically lower than-20F), it is important to make sure that the metals will not fail due to lo of impact resistance.Several tests are required to ensure that unalloyed ferrous materials will behave adequately at low temperatures.At low operating temperatures(the specific temperature depends on the particular material), impact tests may be required on the materials and welds.In some cases, different materials whose properties are better at low temperatures may have to be used.The Code requires each veel component to be reviewed, its minimum design metal temperature(MDMT)calculated, and the controlling MDMT stamped on the veel.低温工况;在低温工况下（通常低于-20F), 确保材料的冲击性能是非常重要的，需要做几项测试。在低温环境下，需要做几项测试来确保合金的低温性能。在很低工作的温度下（具体温度取决于特定的材料），母材和焊缝需要做冲击试验。在某些情况下，不同的材料在低温条件下性能更好。标准规定，容器每个部件都要进行审核，按其最低设计金属温度（MDMT）计算并且在容器上印上最低设计金属温度的控制值。
High-temperature service: Metals have different mechanical strengths that depend on temperaturethe horizontal shellside-vaporization kettle with finned tubes is roughly equivalent in price to the vertical tubeside reboiler with plain tubes.对热力/机械设计进行联合优化，再沸器的成本降低40％，从 186,400 美元降到109,500美元，并且冷凝器的成本减少了65％，从81700美元降到29,000美元（见表1）。翅片管式的水平釜式再沸器和普通的垂直气化再沸器价格上大致相当，最终可能成为替代品。Glycerin/water evaporator.甘油/水蒸发器
Differences in material of construction costs can be significant.Consider a glycerin/water evaporator operating under vacuum.If corrosion were not a problem and carbon steel could be used on the proce side, the equipment cost would be 60% le than if the unit were built of the recommended Type 316L stainle steel.If the proce side of the exchanger were claified as lethal service, the increase in cost to meet the more-stringent construction criteria would be 15%;additional costs would be incurred if the whole unit were to be claified as lethal service(Table 2).材料在制造成本上的差异可能会很大。以真空状态下的甘油/水蒸发器为例。如果没有腐蚀问题，管程和壳程可以用碳钢，这样设备的成本会比使用316L材料减少60％以上。如果换热器的其中一程被认定为危险性工况，如果为满足严格要求费用将提高15%，如果管程和壳程都是危险工况的话成本又会上去（见表2）
Platform feed vaporizer/reactor effluent condenser.Although there are obvious cases that dictate whether a fluid should be placed on the shellside or tubeside to maximize thermal performance, even in cases that look equivalent it is important to at least consider the poibility of switching sides.In this example, platform feed is vaporized from a vapor/liquid mixture at about 165 psia and reactor effluent is partially condensed at about 433 psia.Everything else being equal(such as maintenance requirements, etc.), switching fluid sides reduces the cost by 22%(Table 3).板式物料蒸发器/反应器物料进入冷凝器。虽然有明显的情况下，决定流体是走壳程还是管程，可以最大限度地提高传热性能，但是甚至在某些情况下，看相当于，重要的是，至少要考虑切换流侧的可能性。在这个例子中，物料是从约165 Psia的气液混合物中蒸发出来，和出反应器的物料在433 Psia的压力下冷凝。其他一切条件相同（如维护要求等），切换流体侧能降低成本22％（见表3）。
Project completion time Thermal and mechanical design integration also reduces the overall costs of a project by reducing the project completion time(10).Additional steps, such as drawing generation and vendor interfacing, could be taken in parallel, thereby further reducing the project completion time.This idea of achieving faster project execution has also been referred to as “fast tracking”(11).热力和机械设计一体化降低了项目的整体成本也降低了工程完成时间（10）。另外的步骤可以同时进行，如图纸生成和供应商的接口，从而进一步降低了该项目的完成时间。这种更快完成项目的思想也被称为―快速追踪‖（11）。Conclusion 结论
With the advancement of integrated tools, the project engineer can now design shell-and-tube heat exchangers from beginning to end, including fabrication drawings.The advantages of this once-through approach are significant:
随着集成工具的进步，项目工程师现在可以从项目开始到结束全程跟踪，包括制造图纸设计和管壳式换热器的设计。这一次通过的方法的优点是显著的： reduced costs because of an optimized thermal and mechanical design;因为热力和机械设计的优化降低了成本
Reduced costs as a result of applying ASME rules early in the project and minimizing rework later;
由于在项目初期运用了ASME标准和对返工最小化而减少成本。
Reduced costs aociated with shorter project completion times;and improved cost projections resulting from the simulation of equipment fabrication 缩短项目的完成时间降低成本，并且因进行设备制造的模拟仿真而增加了设计费
15（四-1）管板式换热器的有效设计
Chemical Engineering Progre , Feb 1998 by Mukherjee, Rajiv To make the most of exchanger design software, one needs to understand STHE claification, exchanger components, tube layout, baffling, preure drop, and mean temperature difference.为了充分利用设计软件，人们需要了解固定管板式换热器分类，比如换热器组件，管程布局，折流板位置，压降，以及平均气温差异
Thermal design of shell-and-tube heat exchangers(STHEs)is done by sophisticated computer software.However, a good understanding of the underlying principles of exchanger design is needed to use this software effectively.管壳式换热器热设计(STHEs)是由精密的电脑软件设计的。然而为了有效使用该软件，需要很好的对换热器设计的基本原则。
This article explains the basics of exchanger thermal design, covering such topics as: STHE components;claification of STHEs according to construction and according to service;data needed for thermal design;tubeside design;shellside design, including tube layout, baffling, and shellside preure drop;and mean temperature difference.The basic equations for tubeside and shellside heat transfer and preure drop are wellknown;here we focus on the application of these correlations for the optimum design of heat exchangers.A followup article on advanced topics in shell-and-tube heat exchanger design, such as allocation of shellside and tubeside fluids, use of multiple shells, overdesign, and fouling, is scheduled to appear in the next iue.;S6 M;t5 Q% U: F 这篇文章解释了换热器设计基础，包含的主题例如；固定管板式换热器成分：依照结构和服务对固定管板式换热器的分类：对热设计需要的数据；管程设计；壳程设计，包括换热管的排布和壳程压力降和不同的平均温度。换热器管程壳程的传热导和压力降有一个著名的基本方程。这里我们着眼于这些对换热器优化设计的相关应用。在后续的前沿课题中，比如换热器壳程管程流体的分配，使用多壳程，重复设计以及浪费，是将在下一期提及。Components of STHEs 固定管板式换热器的组件
It is eential for the designer to have a good working knowledge of the mechanical features of STHEs and how they influence thermal design.The principal components of an STHE are: 设计师有一个良好的STHEs的机械性能的知识，以及他们如何影响了热力设计，那是必不可少的。STHEs的主要组成部分是 shell;壳程 shell cover;封头 tubes;换热管 channel;管箱 channel cover;管箱盖 tube-sheet;管板 baffles;折流板 nozzles.接管
（四-2）Other components include tie-rods and spacers, pa partition plates, impingement plate, longitudinal baffle, sealing strips, supports, and foundation.其他内容包括：拉杆和定距管，分程隔板，防冲板，纵向挡板，密封条，支撑件和基础条件。The Standards of the Tubular Exchanger Manufacturers Aociation(TEMA)(1)describe these various components in detail.管壳式换热器制造协会标准（TEMA）详细描述了这些不同的组成部分。
An STHE is divided into three parts: the front head, the shell, and the rear head.Figure 1 illustrates the TEMA nomenclature for the various construction poibilities.Exchangers are described by the letter codes for the three sections for example, a BFL exchanger has a bonnet cover, a two-pa shell with a longitudinal baffle, and a fixed-tubesheet rear head.一个固定管板式换热器分为三个部分：前端管箱，壳体和后端管箱。图一指出了各种结构的TEMA标准术语。用字母来表达换热器的三个部分。BFL换热器就表示前端是封头管箱，中间是具有纵向隔板的双程壳体，后端是与B相似的固定管板结构的封头管箱。
Claification based on construction 基于结构的分类
Fixed tubesheet.A fixed-tubesheet heat exchanger(Figure 2)has straight tubes that are secured at both ends to tubesheets welded to the shell.The construction may have removable channel covers(e.g., AEL), bonnet-type channel covers(e.g., BEM), or integral tubesheets(e.g., NEN).固定管板。固定管板式换热器（图2）是两端带直管的管板焊在壳体的结构。结构可以是带可拆卸平盖管箱（如AEL式），可以是两头是封头管箱式的（如BEM式）或者是两端与管板制成一体的固定管板结构（如NEN式）。
The principal advantage of the fixedtubesheet construction is its low cost because of its simple construction.In fact, the fixed tubesheet is the least expensive construction type, as long as no expansion joint is required.固定管板结构的主要优势在于其结构简单，成本低。事实上，只要不需要加膨胀节，固定管板式的是最便宜的结构形式，Other advantages are that the tubes can be cleaned mechanically after removal of the channel cover or bonnet, and that leakage of the shellside fluid is minimized since there are no flanged joints.其他的优点在于在可拆卸平盖管箱或者封头管箱移除后管程便于机械冲洗。而且由于没有法兰接头壳程的流体泄露将降至最低。
A disadvantage of this design is that since the bundle is fixed to the shell and cannot be removed, the outsides of the tubes cannot be cleaned mechanically.Thus, its application is limited to clean services on the shellside.However, if a satisfactory chemical cleaning program can be employed, fixed-tubesheet construction may be selected for fouling services on the shellside.该设计的一个缺点是带管束的管板焊死在壳体上，所以壳程不能做机械清洗。因此，他的适用范围仅适用于壳程侧流体干净的情况。但是如果可以用有效的化学清洗，固定管板式结构可以用在壳程积垢较高的情况。In the event of a large differential temperature between the tubes and the shell, the tubesheets will be unable to absorb the differential stre, thereby making it neceary to incorporate an expansion joint.This takes away the advantage of low cost to a significant extent.在管壳程温差较大的情况下，管板将不能吸收应力差，因此有必要加上一个膨胀节。而在很大程度上失去了低成本的优势。
U-tube.As the name implies, the tubes of a U-tube heat exchanger(Figure 3)are bent in the shape of a U。
U型管，顾名思义，如图3所示U型管换热器的管子被弯曲成―U‖的形状
There is only one tubesheet in a Utube heat exchanger.However, the lower cost for the single tubesheet is offset by the additional costs incurred for the bending of the tubes and the somewhat larger shell diameter(due to the minimum U-bend radius), making the cost of a U-tube heat exchanger comparable to that of a fixedtubesheet exchanger.U型管换热器只有一个管板，然而这种较低成本的单管板换热器的优势被由换热管弯制和大直径壳体（取决于最小的U形管半径）的产生的额外费用和给抵消了。U形管换热器的制作成本与固定管板式的相当。
The advantage of a U-tube heat exchanger is that because one end is free, the bundle can expand or contract in response to stre differentials.In addition, the outsides of the tubes can be cleaned, as the tube bundle can be removed.U形管的优势在于换热管束的一端是自由的，在应力差作用下管束能自由的伸缩。另外管束外能被清洗，也能被移除。
The disadvantage of the U-tube construction is that the insides of the tubes cannot be cleaned effectively, since the U-bends would require flexible-end drill shafts for cleaning.Thus, U-tube heat exchangers should not be used for services with a dirty fluid inside tubes.U形管的缺点在于管程侧不能有效清洗，因为清洗U形管需要很灵敏的钻轴。所以U形管换热器管程不适用于很脏的流体。
Floating head.The floating-head heat exchanger is the most versatile type of STHE, and also the costliest.In this design, one tubesheet is fixed relative to the shell, and the other is free to “float” within the shell.This permits free expansion of the tube bundle, as well as cleaning of both the insides and outsides of the tubes.Thus, floating-head SHTEs can be used for services where both the shellside and the tubeside fluids are dirty-making this the standard construction type used in dirty services, such as in petroleum refineries.浮头式。浮头式换热器在管板式换热器中是最通用的，也是最昂贵的一种。在设计中，相对于壳体一个管板是固定的，另一个在壳体中作为浮头是自由的。这种可允许自由膨胀的管束也使管束内外都易清洗。因此浮头式的固定管板换热器能被用在管壳两程流体都是很脏的场合，诸如石油精炼。
（四-3）There are various types of floating-head construction.The two most common are the pull-through with backing device(TEMA S)and pullthrough(TEMA T)designs.浮头式换热器的结构有很多种。最常见是钩圈式浮头（TEMA S)和可抽式浮头（TEMA T）The TEMA S design(Figure 4)is the most common configuration in the chemical proce industries(CPI).The floating-head cover is secured against the floating tubesheet by bolting it to an ingenious split backing ring.This floating-head closure is located beyond the end of the shell and contained by a shell cover of a larger diameter.To dismantle the heat exchanger, the shell cover is removed first, then the split backing ring, and then the floating-head cover, after which the tube bundle can be removed from the stationary end.$ Y& X: ]' J X4 O f8 Y.v2 c2 N$ J In the TEMA T construction(Figure 5), the entire tube bundle, including the floating-head aembly, can be removed from the stationary end, since the shell diameter is larger than the floating-head flange.The floatinghead cover is bolted directly to the floating tubesheet so that a split backing ring is not required.如图4，在化工行业里钩圈式浮头是最常用的结构。栓住钩圈使浮头顶盖固定在浮头管板。超出壳体的浮头后端包在一个较大直径的封头里。拆卸换热器时，首先移除壳体，再卸去钩圈，接着就是浮头顶盖，然后管束能从固定端移除。在TEMA T结构中（图5），由于壳体直径比浮头法兰大，管束连带浮头能被整体抽出。这种浮头顶盖直接被螺栓紧固在否头管板上，所以不需要钩圈。
The advantage of this construction is that the tube bundle may be removed from the shell without removing either the shell or the floatinghead cover, thus reducing maintenance time.This design is particularly suited to kettle reboilers having a dirty heating medium where U-tubes cannot be employed.Due to the enlarged shell, this construction has the highest cost of all exchanger types.这种结构的优点就在于无需拆卸壳体或者浮头顶盖就能把管束从壳体里抽出，由此降低了维修时间。这种结构非常适用于工作环境非常脏并且不能用U形管的釜式重沸器。因为壳体直径被扩大了，这种结构在所有的换热器结构中是造价最贵的。# e3 P3 W.~(o8 p* g;l' X There are also two types of packed floating-head construction--outsidepacked stuffing-box(TEMA P)and outside-packed lantern ring(TEMA W)(see Figure 1).However, since they are prone to leakage, their use is limited to services with shellside fluids that are nonhazardous and nontoxic and that have moderate preures and temperatures(40 kg/cm2 and 300 deg C).浮头式结构也有两种形式--填料函式浮头（TEMA P）和带套环填料函式浮头（TEMA W）（见图1）.但是由于容易泄漏，它们的使用范围仅限于壳程流体为无毒无害介质，并且压力40 kg/cm2以下温度在300℃以下
Claification based on service 基于服务的分类
Basically, a service may be singlephase(such as the cooling or heating of a liquid or gas)or two-phase(such as condensing or vaporizing).Since there are two sides to an STHE, this can lead to several combinations of services.基本上，一个服务可以是单相（如冷却加热液体或气体）或者是两相（比如冷凝和蒸发）。因为管板式换热器有两侧，这可能导致有几种组合Broadly, services can be claified as follows: 从广义来讲，可以分为以下几类： single-phase(both shellside and tubeside);单相（管程和壳程）condensing(one side condensing and the other single-phase);冷凝（一侧冷凝过程，另一侧单相）vaporizing(one side vaporizing and the other side single-phase);蒸发（一侧蒸发过程，另一侧单相）
condensing/vaporizing(one side condensing and the other side vaporizing).冷凝/蒸发（一侧冷凝，另一侧蒸发} The following nomenclature is usually used: 下列术语通常用于
Heat exchanger: both sides singlephase and proce streams(that is, not a utility).换热器：两程都是单相的工艺流体
Cooler: one stream a proce fluid and the other cooling water or air.冷却器:一侧工艺流体，另一侧冷却水或者空气
Heater: one stream a proce fluid and the other a hot utility, such as steam or hot oil.加热器：一侧工艺流体，另一侧公用工程热流，如蒸汽或者热的油品。Condenser: one stream a condensing vapor and the other cooling water or air.冷凝器：一侧蒸汽冷凝，另一侧是冷却水或者空气
Chiller: one stream a proce fluid being condensed at sub-atmospheric temperatures and the other a boiling refrigerant or proce stream.深冷器:一侧是被负压状态下被压缩工艺流体，另一侧是沸腾的制冷剂或者工艺流体。Reboiler: one stream a bottoms stream from a distillation column and the other a hot utility(steam or hot oil)or a proce stream.再沸器：一侧是来自蒸馏塔底的流体，另一侧是来自公用工程（蒸汽或者热油品）或者是工艺流体。
This article will focus specifically on single-phase applications.本文将侧重单相场合
Design data 设计数据
Before discuing actual thermal design, let us look at the data that must be furnished by the proce licensor before design can begin:
在讨论实际的热力设计之前，我们必须在提供流程许可的条件下开始研究数据并开始设计: 1.flow rates of both streams.两程流体的流速
2.inlet and outlet temperatures of both streams.两程流体的进出口温度
3.operating preure of both streams.This is required for gases, especially if the gas density is not furnished;it is not really neceary for liquids, as their properties do not vary with preure.两程流体的工作压力。尤其是当没有提供气体密度时，对气体来讲那是必须的；因为液体的属性不随压力变化，所以对于液体不是必须的。
4.allowable preure drop for both streams.This is a very important parameter for heat exchanger design.Generally, for liquids, a value of 0.5-0.7 kg/cm2 is permitted per shell.A higher preure drop is usually warranted for viscous liquids, especially in the tube side.For gases, the allowed value is generally 0.05-0.2 kg/cm2, with 0.1 kg/cm2 being typical.两程流体的许可压力降。对于热力设计来讲那是非常重要的。一般对液体而言壳程的许可压力降为0.5-0.7 kg/cm2。特别在管程，粘性液体压降将更大，允许值一般为0.05-0.2 kg/cm2，一般为0.1 kg/cm2
（五）主题：管壳式换热器鞍座哪一侧为固定端，哪一侧为移动端。
Normally, there are two saddles for horizontal shell-and-tube heat exchangers, one defined as channel side saddle and the other defined as rear head side saddle.通常，水平布置的管壳式换热器有两个鞍座，一个定义为前管箱侧鞍座另一个定义为后管箱侧鞍座。
As you all know, for these two saddles there shall be one “ fixed” and one “ sliding”.Which one is selected as “sliding” to be better design? 众所周知，两个鞍座应该一个固定 一个可移动，哪一个设计做为移动端更好呢？
If there is no special requirements, usually we select the saddle near channel side as “fixed” and the other one near rear head as “sliding”.如果没有特殊要求，通常我么选择靠近前管箱侧为固定端，靠近后管箱出为滑动端 But if piping stre is not a problem, how about reverse the selection: channel side saddle sliding and the other side fixed? 但是如果管道应力不成问题，颠倒方向如何：前管箱侧鞍座为滑动，另一侧为固定？
（六）HTRI流路分析
Definition of A, B, C, E, F Stream as: A,B,C,E,F流路定义：
A-Stream: Tube-to-baffle hole leakage stream;can become rather large in narrow baffle spacing where larger TEMA clearances apply.However, it is effective thermally.This stream is usually smaller for multi-segmental baffles.If you expect a fouling layer deposit thick enough to plug the tube-to-baffle hole clearance, test your design by blocking the A stream on the Clearances panel.Specify the built-up fouling layer thickne for a “safe” design from a preure drop standpoint.A流路：换换热管与折流板孔漏流；采用较大的TEMA标准间隙处漏流在窄折流板间距中相当大。然而这是对传热有效的。这股流体通常在经过多段折流板后变小.如果流体结垢严重足以堵住折流板和换热管孔的间隙，通过规定A 流露的间隙来检验你的设计。从压降角度规定污垢层的厚度。
B-Stream: Main croflow stream through the bundle;normally at least 60 percent of the total flow for turbulent flow and 40 percent for laminar flow.If B stream is lower than these values, examine clearances and baffle spacing carefully.Baffle spacing that is too narrow causes more flow in the A, C, and E streams, thereby decreasing heat transfer.!p)w0 z# g5 T% {!U(E$ E2 W B流路：这是横向掠过管束的主要流路；通常至少60％的总流量为湍流和40％为层流。如果B流路低于这些值，仔细检查间隙和折流板间距。折流板间距太窄则会增加A、C、E流路，因此减少传热。
C-Stream: Bundle-to-shell croflow bypa stream;normally le than 10 percent of the total flow.Incorporate additional sealing strips to decrease flow fraction.C流路:管束和壳体间的间隙产生旁路；通常低于总流量的10%。
F –Stream: Tubepa partition bypa stream;generally should not exceed 10 percent of the total flow.Incorporate additional and/or larger seal rods in the F-stream pa partition to decrease flow fraction.F流路：折流板和壳体间的间隙产生旁路；一般不应超过总流量的10％。在F流路加上额外的或者加大密封条可以减少一小部分F流路。
（七）今日主题；空气冷却器的设计
Highly recommended Technical Paper: ―Effectively Design Air-cooled Heat Exchangers‖ Mukherjee, published on CHEMICAL ENGINEERING PROCESS / FEB 1997 Page 26 to 46.强烈推荐这篇技术文献：《空气冷却器的有效设计》
Abstract: This primer discues the thermal design of ACHEs and the optimization of the;thermal design, and offers guidance on selecting ACHEs for various applications.摘要：这是空气冷却器热力设计的引论以及热力设计的优化，为各种场合选择空冷器并提供指导。
API 661—Petroleum, petrochemical and natural gas industries—Air –Cooled heat exchangers API 661-炼油通用操作空冷式换热器 Applications: 应用场合.•
Forced and induced draft air cooled heat exchangers 强制对流空冷器 •
Recirculation and shoe-box air cooled heat exchangers 3 D •
Hydrocarbon proce and steam condensers 烃类和蒸汽的冷凝 •
Large engine radiators 大型发动机散热器 •
Turbine lube oil coolers 汽轮机润滑油冷却器 •
Turbine intercoolers 涡轮冷却器
Natural gas and vapor coolers 天然气/蒸汽冷凝器 •
Combustion pre-heaters 燃烧预热器 •
Flue gas re-heaters 烟气加热器 •
Lethal service 危险性工况 •
Unique customizations Recommend Vendor: 推荐供货商;
Hudson Products Corporation 哈德森产品公司
GEA Rainey Corporation GEA雷尼公司
Jord International 约旦国际
Korea Heat Exchanger Ind.Co., Ltd. 韩国热交换器工业有限公司
FBM-HUDSON ITALIANA S.P.A.FBM哈德逊公司 Air Cooler Design 空冷器设计 Heat Transfer Basics 传热基础
Air cooled heat exchangers rely on thermodynamic properties of heat transfer.Specifically, heat transfer is energy released over time.Two standard formulas used to calculate heat transfer are as follows: 风冷式换热器传热依靠热力学性质。具体来说，传热是随着时间的推移释放能量。用两个标准公式计算热量。
Duty=Fluid Ma Flow * Cp * △T.负荷=流量*比热容*△T The overall heat-transfer coefficient, U, is determined as follows: 总传热系数U，定义如下：1/U=1/airside heat transfer coefficient+1/tubeside heat transfer+tubeside fouling resistance + airside fouling resistance+ tube wall resistance
1/U=1/空气侧传热系数+1/管程传热系数+管程污垢热阻+空气侧污垢热阻+管壁热阻 Duty=U * Area * LMTD 负荷=U*传热面积*对数平均温差 U is the inverse of sum resistance to heat transfer(defined as above)U是传热热阻之和的倒数（定义如下）
Area is the cooler’s total finned heat transfer area 8 传热面积等于冷却器的总翅片传热系数
LMTD is the Log Mean Temperature Difference, or the driving force of heat transfer 对数平均温差就是温差的对数，或者是传热的推动力
Given the above graph, recommending an absolute minimum of 10°C Delta T for most applications based on economies of scale.Of course smaller Delta T’s, such as 5°F, have been designed.Keep in mind as the ambient increases, the LMTD goes down reducing cooling ability.The optimum temperature is around 15°C-20°C more than the design ambient temperature.Flow Pattern & LMTD Effects There are three main types of flow patterns used in air cooled heat exchangers;counter-current flow, co-current flow and cro current flow.Counter-Current Flow – By far the most common in the proce industry, counter-current flow cools the hottest fluid with the warmest air, and the coldest fluid with the coldest air.In other words, the proce fluid enters the heat exchanger and paes through the finned tubes at the top of the bundle.These top tubes are exposed to air warmed by the lower tube rows.As the proce fluid cools and paes through the lower tube rows, the air temperature is lower as it has been exposed to le and le tube rows.Co-Current Flow – This flow pattern is typically used in procees with critical pour points as it provides the highest outlet proce temperature control since it has the lowest efficiency.In this pattern the ambient air cools the hottest fluid, and the hottest air attempts to cool the coldest fluid.The shaded arrows to the right illustrate this flow pattern.Cro-Current Flow – Most common in the gas compreion industry, the cro-current flow pattern exposes each pa of the proce fluid to the same air stream.Therefore the pa plates inside the headers are vertical, rather than horizontal, to allow the fluid to pa perpendicular to the air stream.Minimizing Air Cooler Costs:
Through understanding the customer’s needs to size and design air cooled heat exchangers use commercially available software programs, typical HTRI, B-JAC etc.These programs, while not offering a thermal guarantee, can offer an advantage to customers when trying to compare air coolers from different manufacturers.Quick selection between multiple designs: •
Maximize tube length while maintaining
Design air cooler with a 1 to 3 ratio.For example, if your cooler is 30’ long it should typically be around 10’ wide.This helps reduce the header size, the most expensive portion of an air cooler, while still maintaining proper fan coverage.•
Minimize tube rows to increase heat transfer effectivene of area, minimize header thickne.Typically between four to six tube rows •
Try and maintain 1‖ tube diameters, depending on service.Even high viscosity services that appear to benefit from larger diameter tubes can typically be designed cheaper with more 1‖ diameter tubes.•
Use a counter-current flow where poible as it reduces surface and potentially minimize header plate thickne.•
Increase your allowable preure drop.This allows more paes in the bundle reducing the cooler size.Components
An air cooled heat exchanger consists of the following components: •
One or more bundles of heat transfer surface.•
An air-moving device, such as a fan, blower, or stack.•
Unle it is natural draft, a driver and power transmiion to mechanically rotate the fan or blower.•
A plenum between the bundle or bundles and the air-moving device.•
A support structure high enough to allow air to enter beneath the ACHE at a reasonable rate.•
Optional header and fan maintenance walkways with ladders to grade.•
Optional louvers for proce outlet temperature control.•
Optional recirculation ducts and chambers for protection against freezing or solidification of high pour point fluids in cold weather.•
Optional variable pitch fan hub for temperature control and power savings.Typical components of an air-cooled heat exchanger Tube Bundle
A tube bundle is an aembly of tubes, headers, side frames, and tube supports as shown in figure below.Usually the tube surface exposed to the paage of air has extended surface in the form of fins to compensate for the low heat transfer rate of air at atmospheric preure and at a low enough velocity for reasonable fan power consumption.Typical construction of tube bundles with plug and cover plate headers The prime tube is usually round and of any metal suitable for the proce, due consideration being given to corrosion, preure, and temperature limitations.Fins are helical or plate type, and are usually of aluminum for reasons of good thermal conductivity and economy of fabrication.Steel fins are used for very high temperature applications.Fins are attached to the tubes in a number of ways:
An extrusion proce in which the fins are extruded from the wall of an aluminum tube that is integrally bonded to the base tube for the full length.•
Helically wrapping a strip of aluminum to embed it in a pre-cut helical groove and then peening back the edges of the groove against the base of the fin to tightly secure it.•
Wrapping on an aluminum strip that is footed at the base as it is wrapped on the tube.Sometimes serrations are cut in the fins.This causes an interruption of the air boundary layer, which increases turbulence which in turn increases the airside heat transfer coefficient with a modest increase in the air-side preure drop and the fan horsepower.The choice of fin types is critical.This choice is influenced by cost, operating temperatures, and the atmospheric conditions.Each type has different heat transfer and preure drop characteristics.The extruded finned tube affords the best protection of the liner tube from atmospheric corrosion as well as consistent heat transfer from the initial installation and throughout the life of the cooler.This is the preferred tube for operating temperatures up to 600°F.The embedded fin also affords a continued predictable heat transfer and should be used for all coolers operating above 600°F and below 750°F.The wrap-on footed fin tube can be used below 250°F;however, the bond between the fin and the tube will loosen in time and the heat transfer is not predictable with certainty over the life of the cooler.It is advisable to derate the effectivene of the wrap-on tube to allow for this probability.There are many configurations of finned tubes, but manufacturers find it economically practical to limit production to a few standard designs.Tubes are manufactured in lengths from 6 to 60 feet and in diameters ranging from 5/8 inch to 6 inches, the most common being I inch.Fins are commonly helical, 7 to 11 fins per inch, 5/16 to I inch high, and 0.010 to 0.035 inch thick.The ratio of extended to prime surface varies from 7:1 to 25:1.Bundles are rectangular and typically consist of 2 to 10 rows of finned tubes arranged on triangular pitch.Bundles may be stacked in depths of up to 30 rows to suit unusual services.The tube pitch is usually between 2 and 2.5 tube diameters.Net free area for air flow through bundles is about 50% of face area.Tubes are rolled or welded into the tube sheets of a pair of box headers.The box header consists of tube sheet, top, bottom, and end plates, and a cover plate that may be welded or bolted on.If the cover is welded on, holes must be drilled and threaded opposite each tube for maintenance of the tubes.A plug is screwed into each hole, and the cover is called the plug sheet.Bolted removable cover plates are used for improved acce to headers in severe fouling services.Partitions are welded in the headers to establish the tube-side flow pattern, which generates suitable velocities in as near countercurrent flow as poible for maximum mean temperature difference.Partitions and stiffeners(partitions with flow openings)also act as structural stays.Horizontally split headers may be required to accommodate differential tube expansion in services
having high fluid temperature differences per pa.The figure below illustrates common head types.Bundles are usually arranged horizontally with the air entering below and discharging vertically.Occasionally bundles are arranged vertically with the air paing acro horizontally, such as in a natural draft tower where the bundles are arranged vertically at the periphery of the tower base.Bundles can also be arranged in an “A” or “V” configuration, the principal advantage of this being a saving of plot area.The disadvantages are higher horsepower requirements for a given capacity and decreased performance when winds on exposed sides inhibit air flow.Within practical limits, the longer the tubes and the greater the number of rows, the le the heat transfer surface costs per square foot.One or more bundles of the same or differing service may be combined in one unit(bay)with one set of fans.All bundles combined in a single unit will have the same air-side static preure lo.Consequently, combined bundles having different numbers of rows must be designed for different face velocities
（八）接下来主题：重沸器设计
“Optimize reboiler Design--Use these guidelines for best performance” ―重沸器最优化设计--使用这些准则使性能最优化
By Edward Chen, public on HYDROCARBON PROCESS/ July 2001, page 61 to 67.―Properly Design Thermosyphon Reboilers‖ 热虹吸重沸器的恰当设计
By Andrew W.Sloley, published on CHEMICAL ENGINEERING PROCESS/ MARCH 1997, Page 52 to 64.)
Ed Chen publiced Fig.2 Flow chart for selecting reboilers and Table 1 Advantiges and disadvantage of Various type reboilers are very useful and helpful for reboiler design.Reboiler type 重沸器形式
*Vertical thermosyphon normally in-tube boiling;立式管程沸腾热虹吸重沸器 *Horizontal thermosyphon normally shell-side boiling;卧式壳程沸腾热虹吸重沸器 *Internal boiling reboilers(bathing-in type)内置式重沸器 *Once-through natural circulation reboilers 自然循环重沸器 *Forced circulation reboilers强制循环重沸器 *Kettle reboilers 釜式重沸器
For a detailed horizontal or vertical thermosyphon reboiler design, if HTRI is available, HTRI can simulate this case.如果可用HTRI进行详尽的卧式或者水平热虹吸再沸器设计，HTRI能模拟这段过程 Key points关键点
1)Proce Flow Diagram or P&ID of the proce system.工艺系统的工艺流程图或者P&ID图1 2)Proce Fluid boiling range / boiling components.工艺液体的沸点范围/沸点组分 3)Fouling;污垢
4)Vaporization percentage;气化率
5)Connecting inlet & outlet piping.进出口管道的连接
6)Column or tower liquid head, its internals and elevation.容器或塔器的液柱压头，其内部容积和高度
Kettle Reboiler Design 釜式重沸器的设计
The maximum heat flux should be 100,000 Btu/hr-ft2(recommended by HTRI).最高的热通量为100,000 Btu/hr-ft2（HTRI推荐值）
The main effects of Kettle parameters on overall performances:在整体性能上釜式重沸器最主要的影响因素
a)Bundle geometry 管束几何形状 b)Overall Delta T壁面过热度 c)Physical properties 物理性能 d)Mixture composition 混合物的组分 e)Preure 压力 f)Surface 表面粗糙度g)Finned tubes(highly effective in low Delta T boiling)翅片管（在低温差的重沸器中高效率）h)Exce(non-condensed)steam 过热蒸汽 The typical Pool Boiling Curve: 典型的大容器沸腾曲线
HTRI B-K-1 Report Page 2-1 gave a different division as followings: Region I: Natural convection: no bubbles are produced, and heat is transferred purely by natural convection.区域I：自然对流：不产生气泡，而且热量仅通过自然对流来传递。
Region II: Incipient Boiling: heat transfer is a combination of single-phrase convection and nuclear boiling.区域II：初始沸腾：热传递由孤立气泡结合和核态沸腾组成。
Region III: Nuclear boiling: Strong bubbling and heat transfer is a function of Delta T.区域III：核态沸腾：剧烈生成气泡并在温差下热传递。
Region IV: Transition boiling: A transition to film boiling, and heat flux paes through a maximum and begin to decrease rapidly with increasing Delta T.Un-expecting operation region/ reboilers shall not design within this region.区域IV：过渡沸腾：像膜态沸腾转变，热流密度达到最大值并且随着壁面过热度的增加而急剧降低。重沸器不应该在此不确定操作区域内进行设计。
Region V: Stable Film boiling: Above certain wall temperature, liquid can no longer stay in contact with the metal surface, and the tube becomes surrounded by a stable vapor film which reduces the heat transfer coefficient.区域V:稳定的膜态沸腾：随着壁温的的升高，液体将不在停留在金属壁面上，管子周围充满了降低热传递效率的稳定的蒸汽膜。
Region VI: Film boiling with increasing radiation: sometimes due to a fixed high heating medium temperature, reboilers had to design within this region.区域VI：伴随热辐射增加的膜态沸腾：由于一个恒定的高温加热介质温度，再沸器不得不在此区间内设计。
（九）“降低管壳式换热器污垢”--正确的设计能降低成本并且提高效率和开车时间。
Common Fouling mechanisms are: 常规的结垢机理为：
Particulate Fouling results from sedimentation of dust, rust, fine sand or other entrained solids.微粒状的污垢来自粉尘、细砂或者其他带入固体的沉积。
Precipitation Fouling is a solids deposition at the heat transfer surface from a supersaturated fluid.沉淀污垢是过饱和液体中固体沉积在传热面上
Chemical reaction Fouing is the breakdown and bonding of unstable compounds at the heat transfer surface.Oil sludge and polymerization are examples of chemical reaction fouling.化学反应污垢是不稳定的化合物在换热面上分解和合成而形成的。油污和聚合就是个化学反应结垢的例子。
Coking is a subset of chemical reaction fouling.It is one of the most problematic types of fouling.In the extreme, the coke deposit is a very hard layer of carbon, salts and other compounds.焦化属于化学反应结垢。这是积垢的最麻烦的类型之一。在极端的情况下，沉积的焦炭是由碳、盐类以及其他化合物组成的坚硬层。
Corrosion Fouling is the accumulation of corrosion products, such as iron oxide, on the heat transfer surface.腐蚀污垢是腐蚀产物的积聚物，诸如换热面上的氧化铁。
Biological fouling is the growth of living organisms, like algae and muels, on the heat transfer surface.生物质污垢是有机生物体在传热面上生长而成，像海藻和贝类。
Fouling is services is often a combination of two or more mechanisms.Also, one mechanism may be initiator for anther mechnism.Fluids may be categorized into three groups according to their potential for fouling 污染往往是由两个或两个以上的机理组合成。而且，一个机理可能引发另一个机理。流体根据抗污能力可分为三类：
Nonfouling fluids do not require regular cleaning.Some examples are nonpolymerzing light hydrocarbons, steam and subcooled boiler feed water.不结垢流体不需要频繁的清洗。如非聚合轻烃、蒸汽以及过冷的锅炉给水。
Asymptotic fouling fluids reach a maximun constant fouling resistance after a short run time.The fluid velocity imports a shear stre at the fouling layer that removes some of the deposit.Cooling water is an example of an asymptotic fouling fluid.渐进型污垢流体在短时间运行时间后达到最大的恒定污垢热阻。流体流速在污垢层形成剪切力以去除部分沉积污垢。冷却水就是渐进型污垢流体的一种
Linear fouling fluids have a fouling layer that is too tenacious to prevent with economic design velocities.The fouling layer thickne is a function of time, velocity, surface temperature.Crude oils and polymerizing hydrocarbons are examples of linear fouling fluids.线性型污垢流体的污垢层由于太坚固以至于在设计流速下都能维持。这种污垢的厚度在于时间、流速、表面温度的集合作用。原油和聚合烃类就是线性污垢流体的例子。
The problem with this approach is that the fouling resistance is not static.Fouling depends on
many factors, especially velocity, surface temperature and chemistry.Actual fouling in service can vary greatly about the mean performace predicted by static fouling factors.This is the most noticeable in exchanger performance where the fouling margin is large.Problematic serviecs, or “frequent foulers”, can reach the performance limit is a matter of days, rather than the full run cycle.Thereafter, the user must clean the exchanger or live the reduced performance.这种趋势的问题在于污垢热阻不是恒定的。污垢取决于很多因素，特别是流速，表面温度和化学成分。工作下的实际污垢和由静态污垢因素来预测的平均值差别很大。大幅区域积垢是换热器性能中最引人注意的地方。有问题的工作状态下，或者频繁积垢的情况下，几天之内就能达到性能极限，不再满负荷运转。之后，用户必须得清理换热器或者调试来适应降低的性能。
One approach to this problem is to further increase the margin for fouling.Unfortunately, this has diminishing returns.Use of large fouling factors can be a self-fulfilling prophecy.Large fouling factors or other safety margins result in added surface area.A design with large surface area will always have lower fluid velocity than a design with le area at the same given preure drop.As surface area is added, velocity decreases.As velocity decrease, fouling increases.Thus, the prophecy is fulfilled.问题会进一步扩大污垢范围。这就会降低盈利。在大量积垢因素下使用会自然的发生情况。大量积垢因素或者其他安全裕度会导致增加表面积。在给定压降前提下一个大表面积的设计中流速会比小面积来的小。随着表面积的正大，流速会降低。随着流速的降低，积垢加剧。因此预测情况必然发生。
An alternate approach is to avoid fouling altogether by designing for critical velocity, surface temperature, and/or other factors that preclude significant fouling.HTRI is leading the effort to determine these critical design parameters.Due to the complexity of fouling, it may be some time before these criteria are fully developed.However, partial results are available now for some problematic refinery applications.通过设计关键流速、表面温度、以及/或者排除显在性污垢来完全避免积垢。HTRI在确定这些关键性设计参数中起到指导的作用。由于积垢的复杂性，这些标准得到充分开发前可能需要花费一段时间。然而，部分结果现已被一些存在问题的炼油厂所应用。
（十）HTRI 报告提取
Most Crude oils not foul exceively when: 当大部分原油结垢不是很严重时： Tubeside velocity above 6.6 ft/s;管程流速在6.6 ft/s以上（2 m/s）Shellside velocity above 2 ft/s;壳程流速在2 ft/s以上（0.6 m/s）
Surface temperature below 570 Degree F.表面温度在570℉以下（298 ℃）
Hydrocarbon mixtures with: 烃类混合物
API gravity
short maintenance cycles;短期维护周期
Problematic thermal or hydraulic performance;传热或水压性能存在问题 Vibration.振动
Reduced Capital Costs:降低资金成本
Must reconcile installed exchanger cost with increased pumping cost.必须对换热器成本和增加的泵运转开销进行协调
Low-fouling design greatly increases run time, but not necearily infinite:低结垢设计大幅增加运转时间，但是没必要无限。
Evaluate need for online cleaning, parallel shells, shell bypa.需要对在线清扫，纵流壳程，壳程旁路进行评估。
Consider impact of turndown operation, including poible pump circle, exchanger velocity if fluid bypa used for temperature control.包括如果流体旁路被用来温度控制，则要考虑夜班操作包括合理的泵循环、换热器流速的影响，Liquid Hydrocarbon Service recommended criteria: 液态烃场合推荐准则： Tube side velocity is greater than 6.6 ft/s(2 m/s);管程流速大于2m/s Wall temperature is le than 570 Degree F(300 Degree C)壁温低于300℃ B-Stream fraction > 0.65 B 流路大于65% Use single segmental baffles 用单弓形折流板
Baffle Cut 20-25% recommended 折流板切口值推荐20-25% If impingement device required: use one row of rods for 90 degree layouts;two rows of rods for staggered layouts;Do not use plates.如果需要防冲装置：用一排90度布置的金属棒；错列布置2排金属棒；不要用板。Window velocity / croflow velocity ratio: tubes in window baffle design lower than 2 but 1~1.5 preferred;NTIW design lower than 3 but 1.5~2 preferred.窗口流速和错流流速之比:窗口处折流板设计低于2，首选1~1.5；窗口不排管设计低于3，首选1.5~2.33 If both fluids within scope: add 20% exce surface;DO NOT USE FOULING FACTORS.如果在范围内有2种流体：额外增加20%的表面；不要用污垢因素。
：If one fluid within scope: consider fouling factor for fluid outside scope(omit fouling factor if fluid is non-fouling);multiply HTC(heat transfer coefficient)of fluid within scope by 0.83 but do not use fouling factor.如果范围内只有一种流体：流体外侧范围考虑污垢因素（如果没有污垢则忽略）；范围内流体热传导系数增加0.83但是不要使用污垢因素
就HTRI软件的计算结果,个人的一些经验吧： 1）check warning meage(some you have to resolve.)2)free vibration(some certain cases you can solve vib-problem with some methods or devices.)3)check overall heat transfer rate V.S.existing heat exchangers or experiences.(I know there is a diagram with curves for usual fluid overall U.)4)Cost(check your design is economical or not.This kind of check may come to shell ID, tube count, material, baffle No.and estimate body flanges & tubesheet etc.)5)Actual preure drop V.S.allowable(velocity, Re-Number, shear stre and so on)
6)thermal resistance(Shell / Tube / Fouling/Metal, which part is controlling? Fouling should be le than 20%.)7)Flow Fractions(A-F, B stream >40%，others le than 15% or 10%.If not, check your Clearance setting.)8)check output V.S.input(sometimes you might make a wrong input of proce data, properties etc.)9)If there is phrase change, check pure componet or not.Mole fraction of noncondensables & percentage should be notified for there is a large amount of noncondensabe.For boiling, a wide temperature range boiling should differ much from narrow range.For reboilers, you need to check maxium heat flux, boling regime etc.)
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