单板层积梁弯曲破坏的试验研究与分析

在万能力学试验机上测试由高频热压方法制造的桦木和椴木单板层积梁的密度、静曲强度(MOR)、弹性模量(MOE)和水平剪切强度等力学性质;讨论LVL(单板层积材)梁受弯曲、水平剪切载荷时的主要破坏形式并得出相关结论。测试结果表明,在该试验条件下,桦木和椴木LVL梁具有较大的密度、MOR和较高的MOE。其主要物理力学性能受树种的影响较大,桦木LVL梁的主要性能均优于椴木LVL梁。当LVL梁受弯曲破坏时,其主要破坏形式为整体断裂破坏、开裂破坏以及混合破坏等3种;受水平剪切应力破坏时,以基材剪切破坏和胶层剪切破坏两种形式为主。     

An easy method to design gas/vapor relief system with rupture disk

Tank discharge gas/vapor flow problems are frequently encountered in both practice and design. To perform this type of design calculation, the first step is to identify whether the flow is choked or not through a trial-and-error solution of an equation for adiabatic flow with friction from a reservoir through a pipe. Developing a direct method without any trial-and-error to identify a choking condition would be helpful for expediting the flow calculations. This paper presents an easy and quick method to identify the choking of gas flow for an emergency relief system consisting of a rupture disk and vent piping. This greatly simplifies the design calculations. The proposed method for validating the venting adequacy of existing ERS circumvents the iteration calculation and the use of Lapple charts. Three case studies for the design of vent piping for rupture disks support the proposed method.     

关于地铁轴流风机叶片发生断裂和出现裂纹的分析

叶片断裂和裂纹是旋转机械中普遍存在的一种安全隐患。对其发生规律进行分析是十分重要的。笔者针对地铁通风系统的某型号 18#轴流式风机发生断裂和出现裂纹的情况 ,采用Star—CD流体计算软件和ANSYS有限元软件计算了有、无软连接两种情况下的风机内流场和风机叶片的内应力。结果表明 ,软连接结构虽然对风机的内流场和叶片内应力有影响 ,但不足以对风机安全运行构成威胁。同时 ,分析了导致叶片断裂和出现裂纹的多种因素 ,并提出了避免类似现象发生的若干建议。     

Consequence modeling of a real rupture of toluene storage tank

Chemicals used in paint industry are generally comprised of toxic and inflammable substances; they may cause serious problems for humans and environment if safety conditions are neglected. In 2012, rupture of a toluene tank in a paint factory in Iran claimed lives of two workers near the tank. The present study is formulated in order to model the incident. The results showed the area prone to flash fire occurrence and extension. Furthermore, radiation was measured in terms of distance to the tank. A bund wall is also assumed around the vessel in order to determine its influence on evaporation in flash fire area, radiation, and maximum concentration of vapor cloud. The results provided important hints on minimum and required distance of electrical equipment or electrical enclosure (PLC) installation from vessels as well as suitable distance between the vessels. Finally, preventive recommendations were proposed to reduce the risk of potential accidents.     

污水处理场厌氧反应器的结构设计要点

介绍污水处理场厌氧反应器的结构特点和工艺要求。为保证安全生产及对污水的处理能力，设计中利用无粘结预应力抗拉能力强、抗裂能力高的特点重点解决好温度应力、裂缝宽度等问题，使得污水处理的厌氧工艺更具推广优势。     

Conceptual design of pressure relief systems

Conceptual design of pressure relief systems is an important stage in the design of a safe process plant. The conceptual design stage consists of the following steps: deciding on the location of pressure relief devices, selecting the general type of pressure relief device for each identified location, i.e. safety valve and/or bursting disc (rupture disc), or other relief device, and selecting the special features for the chosen device type. Some regulations, codes and standards, and a decision tree for the selection of a relief device have been described in the literature. This paper presents four decision trees that have been developed for the different steps in the conceptual design stage. Only positive pressure in pressure vessels is considered here.