U形管换热器设计【含5张CAD图纸】

资源目录里展示的全都有，所见即所得。下载后全都有,请放心下载。原稿可自行编辑修改=【QQ：401339828 或11970985 有疑问可加】 三 英文文献 Mechanical Design of Heat Exchangers The many configurations and types of heat exchangers necessary for the variety of fluids and widerange of temperature and pressure encountered inthe chemical industry make choice of design a complex problem in economics The WIDE RANGE of applications of heat exchangers in the chemical industry has led to a variety of constructions. Many types have been designed to accommodate the simple fluids, solutions, or slurries which must be cooled, condensed, or boiled. The extremes of temperatures and the pressures involved in these processes have also been considered. Standard Heat Exchangers To suit the majority of cases, standard shell-and-tube heat exchangers have developed. The essential parts are the tube sheets, tube bundle, the heads, the shell, shell baffles, and inlet and outlet nozzles. In general, these can be obtained for operating pressures up to 600 p.s.i. and for sizes up to 1200 square feet of heat transfer surface. Straight tube, straight shell, fixed-tube sheet heat exchanger Heat exchanger tube pattern These standards, developed by fabrica-tors, are primarily described by the “Standards of Tubular Exchanger Manufacturing Association.” The fourth edition of this booklet has just been published. A further effort at construction standardization is presently being undertaken by the American Standards Association, through the efforts of Sectional Committee B-78, Standardization of Heat Exchangers for Chemical Industry Use.” Standardization reduces first costs, speeds delivery, and permits interchange of parts. In the chemical industry, because of its dynamic technology, write-off time for process equipment is relatively rapid. First cost is of prime importance, but the first cost of a heat exchanger must be considered, together with many other factors, for the choice of a heat exchanger design is a very complex problem in economics. Important variables in this problem are the cost of outage time or the cost of operating at reduced efficiencies because of fouling, corrosion, leakage, or structural failure. The cost of some modifications can be justified, such as those that permit chemical cleaning or facilitate plugging tubes or replacing surface. Additional costs can be justified when they are necessary to accommodate severe cyclic conditions, or when the fluids involved are lethal. Shell expansion joint Straight tube, floating head heat exchanger Standard U-tube heat exchanger Special Heat Exchangers Sometimes these factors lead to exchanger requirements not covered by the standard tubular exchanger, and nonstandard shell-and-tube exchangers come into the picture, as well as miscellaneous special types, involving coiled tubes, plates, extended surface, and unusual construction materials, such as graphite or glass. Basically, heat exchangers must be designed to be structurally sound for their intended service. Usually, pressure part thicknesses will be satisfactory if they meet the requirements of the ASME Code for Unfired Pressure Vessels. Beyond that, the TEMA Standards are used as a guide. The codes generally call for the use of materials conforming to the specifications of the ASTM. It is also the practice of many heat exchanger users to write their own more or less rigid specifications. Generally speaking, for the low pressure heat exchangers, fabrication requirements and corrosion allowances will be the governing factor in determining tube and shell thicknesses. Accommodating Mechanical and Chemical Cleaning An important consideration in most chemical plant applications is the fouling of the heat exchanger surface. Heat exchangers reflect this problem in a variety of construction details. Most head, channel, and cover plate designs permit ready access to tube ends so that the inside of tubes can be rodded clean. Where cleaning externally is important, the construction may permit removal of the entire tube bundle from the heat exchanger so that access to the outside of the tubes may be gained. While a tube pattern of triangular of space pitch is the most economical and materials, an in-line or square pitch tube pattern results in lanes for mechanical cleaning devices. Where chemical cleaning is possible, vents and drains are used as connections for circulating the solutions in and out. Reducing Stresses Due to Differential Expansion In the first heat exchanger drawing , a fixed-tube sheet arrangement is the simplest and least is shown. This expensive type of construction; but if the fluids on the tube side and shell side are of significantly different tem-peratures, so that the tubes and shell are at different temperatures, there will be a differential expansion between tubes and shell that might cause excessive stresses. The result: of these stresses may be fatigue failure, leaking tubes at the tube seats, or perhaps an acceleration of corrosion. To avoid these types of failures, construction modifications are introduced. One example is an expansion joint in the heat exchanger shell. Another common device is the floating tube sheet. While one end of the tube bundle is secured to the shell, the other end is permitted to float with packed seals to prevent leakage. The U-tube arrangement will accommodate differential expansion between tubes and shell and also different rates of expansion between adjacent tubes. ‘Note the flanged construcdon that permits disassembly and removal of the tube bundle. Bent tube heat exchanger Half-moon supports Disk-donut supports The use of bent tubes between fixed tube sheets is another ccepted means of accommodating differential expansions. An additional advantage claimed for this arrangement is the natural shedding of tube scale which accompanies tube flexing during heating and cooling. Directing Tube-Side and Shell-Side Flow Tube-side flow is channeled readily within the tubes, any number of passes using divider plates within the heat exchanger heads. On the shell side, a variety of devices are employed. Themost common is the half-moon baffling. These drilled plates, while directing the flow back and forth across the tubes, also act as tube supports or spacers. Another familiar baffle is the disk and donut. Longitudinal flow dividers may also be used and, if necessary, tubes may be supported with lattice arrangements which minimize flow obstruction. High pressure closure Tube rolled and seal-welded into tube sheet Preventing Erosion Erosion of heat exchangers in service is generally avoided by designing for low fluid velocities if the fluid is of an erosive nature. Two common mechanical devices are also employed in shell-and- tube exchangers to overcome this problem: the shell-side impingement baffle, and the tube-side bell-mouthed tube insert. Both are employed at fluid inlets. Seal-weld membranes Preventing leakage High pressure and leakage problems go together. A wide variety of standard gaskets are available to suit most applications. For very high pressures, a Bridgeman-type closure may be employed. This device takes advantage of the high pressure to effect the seal. For joining tubes to tube sheets, seal welding or strength welding may be necessary, besides the common tube roiling. For cover plates or closure heads, seal-welded membranes may be employed. These seals can be removed by using a cutter and then be rewelded. Constructions for Reducing Size and Cost When one of the fluids has a low heat transfer coefficient for a easonable pressure drop, the use of extended surface on the heat exchanger is often more economical, as for example, in the aircooled condenser used in the South- west. This surface takes on a number of different forms. Fins or studs may be welded on or mechanically attached to tubing. Some extended surface is produced by rolling or forming the fins from the base tube metal. In general, the least costly means involve mechanical attachment of extended surface, but the best thermal and mechanical bond required by severe service is obtained by welding, brazing, or rolling on the fins or studs. If the outside diameter of the finned surface is no greater than the outside diameter of expanded tube ends, the surface is termed "low fin," and the tubing may be used interchangeably with smooth tubing of the same diameter, thus lending itself well to standard constructions. Typical extended surface arrangements Extended surface may also be used inside tubes. This can be accomplished in cast tubes and also extruded tubes, and some special types of heat exchangers are available with this construction. Plate-type heat exchanger Spiral plate heat exchanger A compact and generally economical arrangement is sometimes achieved by employing plate-type heat exchangers. One such surface arrangement consists of an assembly of flat corrugated plates. Another form is the spiral plate exchanger. More recently, progress has been achieved in the design and fabrication of so-called “packed-surface” heat exchangers wherein extended surface is employed on both sides of the fluid-dividing plates. A variety of fabrication techniques has been developed to accomplish seal, manifolding, and general structural integrity of plate-type heat exchangers, although such exchangers are generally restricted to applications under 200 p.s.i. Provisions for Extreme Corrosion Resistance Where low volume and relatively low pressures and temperatures are in-volved, but highly corrosive conditions exist, impervious graphite and glass have been employed successfully as heat exchanger materials. Graphite can be formed in almost any shape and, thus, typical shell-and-tube heat exchanger designs can be used. The type may depend on whether the fluid on one side or on both sides of the heat exchanger is corrosive. One graphite exchanger arrangement consists of a block with passages in which the corrosive fluids are directed perpendicularly to one another. Glass is used to coat the inside or out side of metal tubes and to line the inside of shells in some heat exchanger constructions. Packed-surface heat exchanger Graphite block heat exchanger The structural strength of one material may be combined with the corrosive resistance of another by employing metallic cladding. A thin layer of stainless steel is often rolled or spot-welded to a less costly base material, such as carbon steel. Electrolytic or chemical plating is also employed to lay a corrosion-resistant film on a structural material. Sometimes fluids employed in a process may not be compatible with the same tubing material. In this case, it is possible to obtain a dual-metal tube, with one material, such as a nickel alloy, on one side and aluminum, for example, on the other. Such tubing is often produced by co-drawing in order to obtain a tight bond between the two materials. 四 英文翻译 机械设计换热器 许多配置和类型的换热器所必需的各种液体和各种温度,压力的过程中所遇到的化学工业做出选择设计得一个复杂的问题 广泛的应用在换热器的化学工业已经成功建成了各种不同的建筑。参与这些进程的许多类型的设计，以适应简单的液体的解决方案：泥浆必须冷却，浓缩等或极端的温度和压力的参与，也被认可。 换热器标准 标准的管壳式换热器的开发要满足大多数情况下。其中重要组成部分是管板，管束的首长，壳牌，壳牌挡板和进风口。一般而言，这些可经营压力可达600防扩散和规模高达1200平方英尺的传热表面。 直管，直壳固定管板换热器 换热管模式 左边:三角间距 右边:在行间距 这些标准，制定法布里卡-因子，主要是描述由“管式换热器标准制造商协会。”。目前正在建设的标准化正在进行的美洲标准协会的努力下断面委员会β - 78 ，“标准化的换热器化学工业使用。” 标准化减少了第一次的费用，交付的速度，并允许交换的部分。在化学工业，由于其动态技术，注销时间，工艺设备相对迅速。首先成本是最重要的，但第一次成本换热器都必须加以考虑和许多其他因素，选择换热器设计是一个非常复杂的问题，经济学。成本停电时间或成本在降低经营效率是重要的变数。因为污染，腐蚀，泄漏，或结构上的失败。一些费用可以合理的修改，如那些允许或化学清洗便利堵管或更换表面。额外的费用可当他们的理由是必要的，以适应严重循环条件时，或在流体参与，致命的。 壳牌伸缩缝 直管，浮头式换热器 标准U型管换热器 特别式换热器 有时，这些因素导致换热要求未涵盖的管状换热器的标准，并非标准的管壳式换热进入，以及其他特殊类型，涉及卷曲管，板，延长表面，和不寻常的施工材料，如石墨或玻璃。 基本上，热交换器必须设计结构要合理。通常情况下，如果他们符ASME规范的阻燃压力容器就是合理的，。除此之外，换热标准有指导作用。这些守则一般要求使用的材料符合规格ASTM标准。这也是实践中许多换热器用户写自己或多或少的规范。一般而言，为低压换热器，制作要求和腐蚀因素要确定管壳厚度。 容纳机械和化学清洗 一个重要的考虑因素在大多数化工厂应用上是污垢的换热器表面。热交换器反映这一问题在不同的施工细节。渠道和盖板设计允许随时获得管两端，使管内可栅干净。清洗外部是重要的，建设可允许清除整个管束的换热器，以便获得外部的管可能上涨。 虽然管模式三角空间是最廉价和材料，一个在管模式清洁设备。凡化学清洗是可能的，喷口和水渠被用作循环连接的解决方案和退出。 由于胀差导致降低强度 固定管板安排是最简单和最不发达国家用的这个昂贵的建筑类型;但是，如果流体的管方和壳牌一边是的显着不同温度下，使管和壳牌都在不同温度下，将有差别扩大管和外壳之间有可能产生过度的压力。其结果是：这些压力可能是疲劳破坏，泄漏管在管席位，或者加速腐蚀。为了避免这些类型的故障，介绍了建设修改。一个例子是一个伸缩缝在换热器壳。另一种较常见的手段是浮动管板。虽然一端管束担保的外壳，另一端是允许的浮动填料密封，以防止泄漏。那个U型管的安排，可容纳管之间的差别扩大和壳牌也有不同的利率和的扩大相邻管。 '注意：在法兰建筑许可证拆卸和拆除管束。 弯曲管换热器 半月支持 磁盘支持 使用弯曲管固定管板是另一种手段，可容纳接受差别扩大。另外一个优点宣称这一安是天然的脱落管规模伴随管伸缩在加热和冷却。 导管方和壳侧流 管端流动渠道容易管内，任何数量的通行证使用除法板换热器内的元首。壳体方面，在不同的设备被使用。那个最常见的是半月形。这些钻钢板，同时指导流动来回跨越管，管也作为支持或间隔。另一个熟悉的挡板是磁盘。纵流分隔也可使用，如果有必要，管可支持格子安排尽量减少流通阻塞。 高压封闭 轧管和密封焊接到管板 防腐蚀 换热器腐蚀的服务一般是通过设计避免低流体的流动速度，如果是一个糜烂的性质。两种常见的机械装置还采用管壳式换热为克服这个问题：在壳侧撞击挡板和管端喇叭口的管插入。两者都是受雇于流体入口。 密封焊膜 防止泄漏 高压和渗漏问题。各种各样的标准垫圈，可满足大多数应用非常高的压力，布里奇曼型关闭可能被应用。这种装置利用高压力作用的印章。加入管子管板，密封焊或焊接强度，除了共同管搅动。掩护板或关闭，密封焊接膜可被使用。这些可以使用切割机除去。 结构化和降低成本 当一个人的液体具有较低的传热系数在一个合理的压降，使用延长表面上的换热器往往是更经济，例如，在空气冷凝器用于西南。这表面上采取了一些不同的形式。鳍或螺栓可焊接或机械连接到油管。有些延长表面生产滚动或形成鳍从金属管的基础。一般情况下，最廉价的手段涉及机械表面附着的延长，但最好的热和机械债券所要求的严重的服务，得到了焊接，钎焊，或滚动的鳍或螺栓。 如果外直径的翅片表面不大于外直径的扩大管两端，表面被称为“低肋”并且油管可交替使用，光滑管的直径相同，因此用于标准建设 扩展表面也可使用内部管。这可以铸造管，也挤压管，而一些特殊类型的换热器，可与此建造。 典型表面状延长 契约和一般经济的安排，有时达到雇用板式换热器。这样一个表面安排平板瓦楞纸板， 没有其他形式的螺旋板换热器。最近，已取得很大进展的设计和制造的所谓“包装面” ，其中延长热交换器表面采用两边的流体划分板块。各种各样的制造技术已经开发完成印章， 一般结构完整性，板式换热器，尽管这种热交换器一般仅限于申请200磅。 板式换热器 螺旋板换热器 规定极耐腐蚀性 低量和相对较低的压力和温度有关，但高度腐蚀性的条件存在，不透水的石墨和玻璃 已成功地为换热器的材料。石墨可以形成几乎任何形状，因此，典型的管壳式换热器的设计都可以使用。该类型可取决于流体一方或双方的换热器具有腐蚀性。交换安排由一个块通道构成，其中腐蚀性的液体是针对垂直彼此的。玻璃是用于涂层的内部或外部的金属管，并线的内侧弹在一些换热器结构。 便携表面换热器 石墨块换热器 结构强度的材料可以是一个抗侵蚀性的，另一种采用金属包层。薄薄的一层不锈钢往往推出或点焊一个成本较低的基础材料，如碳素钢。电解或化学镀也雇用奠定耐腐蚀膜结构材料。 有时流体就业过程中可能不符合同一油管材料。在这种情况下，有可能用上铝管其中的材料，如镍合金。这种管材生产的往往是制作，以便获得最适合的材料。