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(at m)=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 3000 psi 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。 Pressure Vessels and Their Components Pressure Vessels are leakproof containers, They are made in all sizes and shapes The smaller ones may be no larger than a fraction of an inch in diameter，whereas the larger vessels may be 150 ft or more in diameter Some are buried in the ground or deep in the ocean； most are positioned on the ground or supported on platforms; and some actually are found in storage tanks and hydraulic units in aircraft。 The internal pressure to which process equipment is designed is as varied as the size and shape. Internal pressure may be as low as 1 in. water gage pressure to as high as 300000 psi or more. The usual range of pressure for monoblock construction is about 1 5 to about 5000 psi, although there are many vessels designed for pressure below and above that range The ASME Boiler and Pressure code， Section Viii，Division 1， specifies a range of internal pressure from 15 psi at the bottom to no upper limit； however， at an internal pressure above 300 psi, the ASME Code, VIII-1, requires that special design considerations may be necessary. Typical components of pressure vessels are described below Cylindrical Shell Cylindrical shell is very frequently used for constructing pressure vessels in the petrochemical industry. It is easy to fabricate and install and economical to maintain. The required thickness is generally controlled by internal pressure， although in some instances applied loads and external pressure have contro1. Other factors such as thermal stress and discontinuity forces may also influence the required thickness Formed Heads A large variety of end closures and transition sections are available to the design engineer. Using one configuration versus another depends on many factors such as method of forming, material cost， and space restriction. Subject to uniform internal pressure of the head of the strength calculation, as the cylinder head and connected, so need to take into account not only the head itself, caused by internal pressure due to film stress, but also connected with the cylinder Department discontinuous stress. Total stress junction head size and the geometric shape and size, and cylinder head thickness ratio of the size. However, the thickness of the head design derived formula, the main use of the internal pressure based on thin-film stress, and will have a discontinuous effect of stress in order to enhance the impact of stress to enhance the form factor calculation in the introduction of the thickness. Stress enhanced by the torque coefficient is derived analytic theory, and experiment with the amendment. Some frequently used formed heads are: Flanged Heads These heads are normally found in vessels operating at low pressure such as gasoline tanks, and boilers. They are also used in high pressure applications where the diameter is small. Various details for their design and construction are given by the ASME, Code, VIII 一 1. Hemispherical Heads . Generally， the required thickness of hemispherical heads due to a given temperature and pressure is one-half that of cylindrical shells with equivalent diameter and material. Hemispherical heads are very economical when constructed of expensive alloys such as nickel and titanium either solid or clad. In carbon steel, however, they are not as economical as flanged and dished heads because of the high cost of fabrication Hemispherical heads are normally fabricated from segmental “gore” sections or by spinning or pressing. Because hemispherical heads are thinner than cylindrical shells to which they are attached， the transition area between the heads and shell must be contoured so as to minimize the effect of discontinuity stress Elliptical and Torispherical (Flanged and Dished)Heads These heads are very popular in pressure vessels. Their thickness is usually the same as the cylinder to which they are attached This reduces considerably the weld build-up Elliptical head is a short half-ellipsoid and cylinder components. Section of straight edge is to avoid head and the cylinder appeared weld connection to the radius of curvature, as mutations in order to improve the situation of the weld force. As the head part of the warp ellipsoidal smooth continuous changes in curvature, so the stress is distributed more evenly, and the depth of the oval head much smaller than the hemispherical head, easy to press molding, is currently in the application of more low-pressure vessel closure the first one. Butterfly is the band head of the spherical head fold, from a radius of R of the spherical body, the transition radius r and a short cylindrical shell ring is composed of three parts and so on. From the geometry, the butterfly is not straight head surface, mutations in the meridian radius of curvature of the junction of two surfaces, due to the curvature of the larger changes in the edge of the existence of a greater bending stress. The edge bending stress and membrane stress superposition, so that part of the stress is much higher than other parts of the body, it forces poor. However, the existence of the transition ring shell reduces the depth of the head to facilitate the molding process, and the suppression of the steel head butterfly processing simple, so that head butterfly wider range of applications. Thus， because the required thickness in areas away from the knuckle region is less than the furnished thickness, the excess can be advantageously used in reinforcing nozzles in these areas. Many mills can furnish such heads in various diameters and thickness that are competitive in price. Conical and Toriconical Heads These heads are used in hoppers and towers as bottomed closures or as transition sections between cylinders with different diameters. The cone-to-cylinder junction must be considered as part of the cone design due to the high unbalanced forces at the junction As a result of the discontinuous, conical shell of the stress distribution is not ideal, but the structure of their particular form of benefit and suspended solid particles or viscous liquid emissions, different diameter cylinders can be used as an intermediate transition section, therefore, more commonly used in the low-pressure containers. Conical heads strength in part from pressure caused by stress and cone shell membrane and the cylinder at both ends of the edge junction stress decision. Cone shell design, the calculation should be the thickness of cone shell, cone shell big and strengthen paragraph little-end thickness. If we are to consider the thickness of only one component, then check the above part of the maximum thickness. Because of these high forces， the ASME Code, -1, limits the apex angle to a maximum of 30when the cone is subjected to internal pressure. Above30 discontinuity analysis is done or a toriconical head used to avoid the unbalanced forces at the junction. Blind Flanges， Cover Plates， and Flanges One of the more common types of closures for pressure vessels is the unstayed flat head or cover. This may be either integrally formed with the shell or welded to the shell， or it may be attached by bolts or some quick-opening device . . Calculate the thickness of flat cover plate to a round-based stress analysis. In the theoretical analysis of the surrounding support plate is considered clamped or simply supported, but in fact covered with the cylindrical flat connection, the real is neither supporting nor clamped simply supported, but between clamped and simply supported the Inter. Therefore often used engineering calculation based on the theory of a round plate of the empirical formula, through the coefficient K to reflect the level of support to build the surrounding circumstances, K value the more the closer Xiaoping cover clamped around; the other hand the more closer to simply supported It may be circular， square， rectangular， or some other shape. Those circular flat heads that are bolted into place utilizing a gasket are called blind flanges Those circular flat heads that are bolted into place utilizing a gasket are called blind flanges Although flat heads or blind flanges may be either circular or noncireular，they usually have uniform thickness. Openings and Nozzles All process Vessels require openings to get the contents in and out. For some vessels， where the contents may be large or some of the internal parts may need frequent changing， access is made through large openings in which the entire head or a section of the shell is removed However， for most process vessels, the contents enter and exit through openings in the heads and shell to which nozzles and piping are attached. In addition to these openings others may be required， such as those for personnel entering the vessel through a manway opening Manhole structure mainly depends on operating pressure, operating medium and the frequency of opening. According to the use of requirements, commonly used in the form of manhole structure are as follows: pressure level manhole cover, manhole compression, fast and so open manhole. Other openings may be necessary for inspecting the Vessel from outside through a handhole opening， and still others may be required for cleaning or draining the vessel. Hand-hole structure of the simplest forms is installed in a blind to take over the board, such a structure for the atmospheric pressure and low-voltage, and do not have regular open forums. The need for rapid hand headstock hole, clamping device should be set up quickly. These openings do