过程装备与控制工程专业英语.doc

Reading Material 16 Pressure Vessel CodesHistory of Pressure Vessel Codes in the United States Through the late 1800s and early 1900s, explosions in boilers and pressure vessels were frequent. A firetube boiler explosion on the Mississippi River steamboat Sultana on April 27, 1865, resulted in the boats sinking within 20 minuted and the death of 1500 soldiers going home after the Civil War. This type of catastrophe continued unabated into the early 1900s. In 1905, a destructive explosion of a firetube boiler in a shoe factory in Brockton, Massachusetts, killed 58 people, injured 117 others, and did $400000 in property damage. In 1906, another explosion in a shoe factory in Lynn, Massachusetts, resulted in death, injury, and extensive property damage. After this accident, the Massachusetts governor directed the formation of a Board of Boiler Rules. The first set of rules for the design and construction of boilers was approved in Massachusetts on August 30, 1907. This code was three pages long. In 1911, Colonel E. D. Meier, the president of the American Society of Mechanical Engineers, established a committee to write a set of rules for the design and construction of boilers and pressure vessels. On February 13, 1915, the first ASMEBoiler Code was issued. It was entitled Boiler Construction Code, 1914 Edition. This was the beginning of the various sections of the ASME Boiler and Pressure Vessel Code, which ultimately became Section 1, Power Boilers. The first ASME Code for pressure vessels was issued as Rules for the Construction of Unfired Pressure Vessels, Section , 1925 edition. The rules applied to vessels over 6 in. in diameter, volume over 1.5 , and pressure over 30 psi. In December 1931, a Joint API-ASME Committee was formed to develop an unfired pressure vessel code for the petroleum industry. The first edition was issued in 1934. For the nest 17 years, two separated unfired pressure vessel codes existed. In 1951, the last API-ASME Code was issued as a separated document. In 1952, the two codes were consolidated into one code-the ASME Unfired Pressure Vessel Code, Section . This continued until the 1968 edition. At that time, the original code became Section , Division 1, Pressure Vessels, and another new part was issued, which was Section , Division 2, Alternative Rules for Pressure Vessels. The ANSI/ASME Boiler and Pressure Vessel Code is issued by the American Society of Mechanical Engineers with approval by the American National Standards Institute (ANSI) as an ANSI/ASME document. One or more sections of the ANSI/ASME Boiler and Pressure Vessel Code have been established as the legal requirements in 47 states in the United Stated and in all provinces of Canada. Also, in many other countries of the world, the ASME Boiler and Pressure Vessel Code is used to construct boilers and pressure vessels. Organization of the ASME Boiler and Pressure Vessel Code The ASME Boiler and Pressure Vessel Code is divided into many sections, divisions, parts, and subparts. Some of these sections relate to a specific kind of equipment and application; others relate to specific materials and methods for application and control of equipment; and others relate to care and inspection of installed equipment. The following Sections specifically relate to boiler and pressure vessel design and construction. Section Power Boilers (1 volume) Section Division 1 Nuclear Power Plant Components (7 volumes) Division 2 Concrete Reactor Vessels and Containment (1 volume) Code Case Case 1 Components in Elevated Temperature service (in Nuclear Code N-47 Case book) Section Heating Boilers (1 volume) Section Division 1 Pressure Vessels (1 volume) Division 2 Alternative Rules for Pressure Vessels (1 volume) Section Fiberglass-Reinforced Plastic Pressure Vessels (1 volume) A new edition of the ASME Boiler and Pressure Vessel Code is issued on July 1 every three years and new addenda are issued every six months on January 1 and July 1. The new edition of the code becomes mandatory when it appears. The addenda are permissive at the date of issuance and become mandatory six months after that date. Worldwide Pressure Vessel Codes In addition to the ASME Boiler and Pressure Vessel Code, which is used worldwide, many other pressure vessel codes have been legally adopted in various countries. Difficulty often occurs when vessels are designed in one country, built in another country, and installed in still a different country. With this worldwide construction this is often the case. The following list is a partial summary of some of the various codes used in different countries: Australia Australian Code for Boilers and Pressure Vessels, SAA Boiler Code (Series AS 1200):AS 1210, Unfired Pressure Vessels and Class 1 H, Pressure Vessels of Advanced Design and Construction, Standards Association of Australia. France Construction Code Calculation Rules for Unfired Pressure Vessels, Syndicat National de la Chaudronnerie et de la Tuyauterie Industrielle (SNCT), Paris, France. United Kingdom British Code BS. 5500, British Standards Institution, London, England. Japan Japanese Pressure Vessel Code, Ministry of Labour, published by Japan Boiler Association, Tokyo, Japan; Japanese Standard, Construction of Pressure Vessels, JIS B 8243, published by the Japan Standards Association, Tokyo, Japan; Japanese High Pressure Gas Control Law, Ministry of International Trade and Industry, published by The Institution for Safety of High Pressure Gas Engineering, Tokyo, Japan. Italy Italian Pressure Vessel Code, National Association for Combustion Control (ANNCC), Milan, Italy. Belgium Code for Good Practice for the Construction of Pressure Vessels, Belgian Standard Institute (IBN), Brussels, Belgium. Sweden Swedish Pressure Vessel Code, Tryckkarls kommissioner, the Swedish Pressure Vessel Commission, Stockholm, Sweden.压力容器准则美国的压力容器规范历史 在19世纪和20世纪初期，锅炉和压力容器频繁发生爆炸事件。1865年4月27日，苏丹轮船的火管锅炉在密士西比河爆炸，导致轮船在20分钟内沉没，且参加南北战争的1500准备回家的士兵全部死忙。这类大灾难一直持续到20世纪初期。1905年，马萨诸塞州布拉克顿一鞋厂发生毁灭性的火管锅炉爆炸事件，造成58人死亡，117人受伤，财产损失400000$。1906年，马萨诸塞州林恩一个鞋厂发生爆炸，导致死亡，受伤，且持续性损失。这次意外后，马萨诸塞州州长组织成立锅炉标准委员会。1907年8月30日，第一部锅炉设计及结构规范获得通过，长达3页。 1911年，德梅尔上校，美国机械工程师学会主席，成立一个委员会来编写锅炉及压力容器的设计和结构规范。1915 2月13日，第一个美国机械工程师学会锅炉规范发布，叫做锅炉构造规范，1914版本。这是系列美国机械工程师学会锅炉及压力容器规范的开端，最终变成第一章电站锅炉。 第一部关于压力容器的机械工程师协会标准作为热交换器结构规则发布，共8章，1925版本。规定容器直径为6英尺，体积为1.5英尺，并且压力为 每平方英寸30磅。1931年12月，美国石油组织-美国机械工程师学会委员会成立并致力于研究用于石油工业的热交换器规则。1934开始发行第一个版本。接下来的17年，就有两部分离热交换器规则。1951年，美国石油组织与美国机械工程师协会标准作为单独文件发布。1952年，这两部规则合并成一部-美国机械工程师学会热交换器规则，共8章。一直延续到1968年版。那时，原始的规则变成8章，1部是压力容器，另一部分是2章的压力容器替换规则。 美国国家标准协会美国机械工程师学会锅炉及压力容器规则由美国机械工程师学会发布，由美国国家标准协会批准的作为美国国家标准协会美国机械工程师学会文件。更多的美国国家标准协会美国机械工程师学会锅炉及压力容器规则在美国47州和加拿大所有城市作为法定使用。同时，世界上许多其他国家使用美国机械工程师学会锅炉及压力容器规则来制造造锅炉及压力容器。 ASME 锅炉及压力容器规范 美国机械工程师学会锅炉及压力容器规则分成许多章。有些章节涉及到一些特殊设备及使用；有些涉及到特殊材料和设备的操作和控制方法；其他的涉及到设备的安装及维护等。下面的章节与锅炉及压力容器设计和结构有关。 第一章 电站锅炉（1卷） 第3章 节1 核电站元件（卷） 节2 混凝土电抗器容器及防范（1卷） 规则事例 事例1，高温保养元件（核的规则手册的氮-47） 第7章 锅炉供暖（1卷） 第8章 节1 压力容器（1卷） 节 压力容器替换规则（1卷） 第9章 玻璃钢压力容器（1卷） 每三年发布一次新版美国机械工程师学会锅炉及压力容器规则，每六个月发布新的附录，分别是1月1日和7月1日。每当新版规则发布就强制执行，附录的发行允许不执行，但即日起六个月后腰强制执行。 压力容器国际规范 除国际使用的美国机械工程师学会锅炉及压力容器规则外，许多其他的压力容器规范在多个国家可以使用。在一个国家设计的容器在他国使用时经常发生故障，这种情况常发生在国际性结构。 下面的目录是被用于列国中的各种规则的一部分的一些摘要信息： 澳大利亚 锅炉及压力容器的澳大利亚规则，表面活性剂锅炉规范（1200系列）:系列1210，热交换器，先进的压力容器设计和结构，澳大利亚标准协会。 法国 热交换器结构规则计算规则，巴黎，法国。 英国 反散射能谱法英国规则。5500，英国标准协会，伦敦，英国。 日本 日本压力容器规范，劳工部，由日本锅炉协会出版，东京，日本；日本标准，压力容器结构，日本工业标准B，8243，由日本标准协会出版，东京，日本；日本高压气体管制法，日本通商产业省，由安全的高压气体工程师协会出版，东京，日本。 意大利 意大利压力容器规范，燃烧过程控制（anncc）国家协会，米兰，意大利。 比利时 国际惯例压力容器结构规则，比利时的标准协会，布鲁塞尔，比利时。 瑞典 瑞典压力容器规范，tryckkarls kommissioner，瑞典压力容器试运行，斯德哥尔摩，瑞典。 Reading Material 17Stress CategoriesThe various possible modes of failure which confront the pressure vessel designer are:(1)Excessive elastic deformation including elastic instability.(2)Excessive plastic deformation.(3)Brittle fracture.(4)Stress rupture/creep deformation (inelastic).(5)Plastic instability-incremental collapse.(6)High strain-low cycle fatigue. (7)Stress corrosion.(8)Corrosion fatigue.In dealing with these various modes of failure, we assume that the designer has at his disposal a picture of the state of stress within the part in question. This would be obtained either through calculation or measurements of the both mechanical and thermal stresses which could occur throughout the entire vessel during transient and steady state operations. The question one must ask is what do these numbers mean in relation to the adequacy of the design? Will they insure safe and satisfactory performance of a component? It is against these various failure modes that the pressure vessel designer must compare and interpret stress values. For example, elastic deformation and elastic instability (buckling) cannot be controlled by imposing upper limits to the calculated stress alone. One must consider, in addition, the geometry and stiffness of a component as well as properties of the material.The plastic deformation mode of failure can, on the other hand, be controlled by imposing limits on calculated stresses, but unlike the fatigue and stress corrosion modes of failure, peak stress does not tell the whole story. Careful consideration must be given to the consequences of yielding, and therefore the type of loading and the distribution of stress resulting therefrom must be carefully studied. The designer must consider, in addition to setting limits for allowable stress, some adequate and proper failure theory in order to define how the various stresses in a component react and contribute to the strength of that part.As mentioned previously, different types of stress require different limits, and before establishing these limits it was necessary to choose the stress categories to which limits should be applied. The categories and sub-categories chosen were as follows:A.Primary Stress.(a) General primary membrane stress.(b) Local primary membrane stress.(c) Primary bending stress.B.Secondary Stress.C.Peak Stress.The major stress categories are primary, sec9ondary, and peak. Their chief characteristics may be described briefly as follows:(a) Primary stress is a stress developed by the imposed loading which is necessary to satisfy the laws of equilibrium between external and internal forces and moments. The basic characteristic of a primary stress is that it is not self-limiting. If a primary stress exceeds the yield strength of the material through the entire thickness, the prevention of failure is entirely dependent on the strain-hardening properties of the material.(b) Secondary stress is a stress developed by the self-constraint of a structure. It must satisfy an imposed strain pattern rather than being in equilibrium with an external load. The basic characteristic of a secondary stress is that it is self-limiting. Local yielding and minor distortion can satisfy the discontinuity conditions or thermal expansions which cause the stress to occur.(c) Peak stress is the highest stress in the region under consideration. The basic characteristic of a peak stress is that it causes no significant distortion and is objectionable mostly as a possible source of fatigue failure. The need for dividing primary stress into membrane and bending components is that, as will be discussed later, limit design theory shows that the calculated value of a primary bending stress may be allowed to go higher than the calculated value of a primary membrane stress. The placing in the primary category of local membrane stress produced by mechanical loads, however, requires some explanation because this type of stress really has the basic characteristics of a secondary stress. It is self-limiting and when it exceeds yield, the external load will be resisted by other parts of the structure, but this shift may involve intolerable distortion and it was felt that must be limited to a lower value than other secondary stresses, such as discontinuity bending stress and thermal stress.Secondary stress could be divided into membrane and bending components, just as was done for primary stress, but after the removal of local membrane stress to the primary category, kit appeared that all the remaining secondary stresses could be controlled by the same limit and this division was unnecessary.Thermal stress are never classed as primary stresses, but they appear in both of the other categories, secondary and peak. Thermal stresses which can produce distortion of the most complete suppression of the differential expansion, and thus cause no significant distortion, are classed as peak stresses.One of the commonest types of peak stress is that produced by a notch, which might be a small hole or a fillet. The phenomenon of stress concentration is well-known and requires no further explanation here. Many cases arise in which it is not obvious which category a stress should be placed in, and considerable judgment is required. In order to standardize this procedure and use the judgment of the writers of the Code rather than the judgment of individual designers, a table was prepared covering most of the situations which arise in pressure vessel design and specifying which category each stress must be placed in.The potential failure modes and various stress categories are related to the Code provisions as follows:(a) The primary stress limits are intended to prevent plastic deformation and to provide a nominal factor of safety of the ductile burst pressure.(b) The primary plus secondary stress limits are intended to prevent excessive plastic deformation leading to incremental collapse, and to validate the application of the elastic analysis when performing the fatigue evaluation.(c) The peak stress limit is intended to prevent fatigue failure as a result of cyclic loading.(d) Special stress limits are provided for elastic and inelastic instability.Protection against brittle fracture are provided by material selection, rather than by analysis. Protection against environmental conditions such as corrosion and radiation effects are the responsibility of the designer. The creep and stress rupture temperature range will be considered in later condition.应力类型压力容器设计者遇到的多种可能的失效形式：（1） 过度弹性变形包括弹性失稳。（2） 过度塑性变性。（3） 脆性断裂。（4） 应力断裂/蠕变变形（非弹性的）。（5） 塑性不稳性增加失稳。（6） 高应变低周期疲劳。（7） 应力腐蚀。（8） 疲劳腐蚀。在处理这些不同的失效形式上，我们假设设计者在局部问题的处理上，有一副应力状态图。这需要通过对机械和热应力的计算或测量来得到，它们（应力）在短暂稳定的状态操作期间，存在于整个容器中。有人会问，这些数据与设计的合理性有什么关系？它们能确保一个构件的安全和满意的性能吗？它与这些各种各样的失效形式对立，压力容器设计者必须比较和说明应力值。例如，通过单独计算应力来强加上限，是不能控制弹性变形和弹性失稳。此外，还必须考虑构件的几何形状和硬度，以及材料的特性。从另一方面来看，塑性变形失效形式可以通过在计算的应力上强加极限来控制，但不象疲劳和应力腐蚀失效形式，峰值应力不做整体描述。必须对屈服结果进行仔细考虑。因此，载荷的类型和由那里引起的应力分布，必须被仔细研究。除了限制许用应力外，设计者还必须考虑一些适当的失效理论，来解释各种应力怎样在构件内起作用和对那些部分的强度所做的贡献。正如前面所涉及的，不同类型的应力需要不同的限制，在确定这些限制之前，选择应用于什么限制的应力类型是必要的。供选择的应力类型如下：A、 主应力。（a）普通的薄膜主应力（b）内部薄膜主应力（c）主要弯曲应力B、 副应力 C、 最大应力应力类型是主应力、副应力及最大应力。它们的主要特征简略描述如下：（a） 主应力是由施加载荷产生的应力，载荷在满足外部和内部的作用力和力矩之间的平衡规律是必要。一次应力的基本特征是自身不受限制。在整个厚度上，如果一次应力超过了材料的屈服强度，防止失效必须完全依赖材料的变形硬化性质。（b） 副应力是由结构的自身约束二产生的应力。它必须满足一个强加应变的式样，而不是与一个外载荷平衡。副应力的基本特征是自身受限制。局部屈服和较小变形，能够满足引起应力产生的不连续条件或者热膨胀。（c） 最大应力是所考虑范围内的最高应力。峰值应力的基本特征，是不会引起大的变形和作为疲劳失效一个可能的源头是令人讨厌的。将主应力分成薄膜和弯曲部分的必要，以后再讨论，极限设计理论表明主弯曲应力的计算值允许高于主薄膜应力的计算值。然而，我们应该解释一下由机械载荷产生的局部薄膜应力的主要种类的位置，因为这种应力确实有副应力的基本特征。它是自身受限制的，而且当它超过屈服极限后，外载荷将受到结构的其他部分抵抗，但这种转变可能会产生严重变形，因此必须将它限制在比其他副应力更小的值，例如不连续弯曲应力和热应力。正如主应力那样，副应力被分为薄膜和弯曲部分，但是，在将局部薄膜应力归到主应力类型后，就会有所有剩余的副应力被相同的限制控制，这种分划是没有必要的。热应力从来不被归类为主应力，但它却出现在其他两种类型中，副和最大应力中。能够通过大部分抑制小膨胀而产生变形，以及不会引起严重变形的热应力，被归为最大应力。最大应力的一个最普通的类型，是由缺口引起的，它可能是一个小洞或一条裂痕。我们都知道应力集中现象，这里不做进一步解释。许多情况出现在不明显的地方，一种应力该归纳为哪种，需要考虑到判断能力。为了使这个程序规范化，并且使用规范作者的判断法，而不是个别设计者的判断法，准备一份能够包括大多数情况的表格，这些情况出现在压力容器设计和详细说明中，每种应力都必须填入其中。潜在的失效形式和各种应力类型，与规范条款有如下的联系：（a）主应力的限制，目的是防止塑性变形，并在韧性爆破压力上提供一个名义安全因素。(b)主应力和副应力的限制，目的是防止导致失稳增加的过量塑性变形和做疲劳估算时， 确认弹性分析的应用。(c)最大应力的极限，目的是防止因周期载荷产生的疲劳失效。(d)特殊应力的限制，提供给弹性和非弹性失稳。应对脆性断裂的保护，是通过材料的选择，而不是分析提供的。对环境条件比如腐蚀和辐射的保护，是每个设计者的职责。蠕变和应力断裂的温度范围，将在以后的章节中考虑。Reading Material 18Packed TowersIn comparison with tray towers, packed towers are suited to small diameters (24 in. or less), whenever low pressure is desirable, whenever low holdup is necessary, and whenever plastic or ceramic construction is required. Applications unfavorable to packings are large diameter towers, especially those with low liquid and high vapour rates, because of problems with liquid distribution, and whenever high turndown is required. In large towers, random packing may cost more than twice as much as sieve or valve trays. Depth of packing without intermediate supports is limited by its deformability; metal construction is limited to depths of 20 25 ft, and plastic to 10 15 ft. Intermediate supports and liquid redistributors usually are needed every 2.5 3 tower diameters for Raschig rings and every 5 10 diameters for Pall rings, but at least every 20 ft. The various kinds of internals of packed towers are represented in Fig. 4.2 whose individual parts may be described one-by-one. (a) is an example column showing the inlet and outlet connections and some of the kinds of internals in place. (b) is a combination packing support and redistributor that can also serve as a sump for withdrawal of the liquid from the tower. (c) is a trough-type distributor that is suitable for liquid rates in excess of 2 gpm/sqft in towers 2 feet and more in diameter. They can be made in ceramics or plastics. (d) is an example of a perforated pipe distributor which is available in a variety of