锆钢复合板设备检漏结构改进及检验方法实践

设计合理的检漏结构和检验方法．是保证醋酸和醋酐装置中关键复合板设备质量要求最行之有效的方式之一。本文以锆钢复合板设备为实践基础，从复合板的物理性能、设备使用工况和制造工艺出发，对复合板设备原有的检漏结构进行了改进，通过合理的检验方法对设备复层焊缝进行密封性检验，保证了设备的安全性和可靠性。     

基于混沌理论的城市供水系统漏损检测新方法

针对漏损检测对城市供水系统节能降耗的重要性,研究时用水量的混沌特性并提出一种基于混沌理论的漏损检测新方法,利用沿程用户时用水量的混沌演化特性来检测漏损故障和漏水。根据城市时用水量的时间序列,提取关联维数、最大Lyapunov指数、吸引子相图和R/S等混沌特征指数,分析沿程城市用水量观测序列的分形和链级混沌关联,并在此基础上,依据系统相图和最大Lyapunov指数变化来比较漏损故障和漏水时序的不同混沌特性。仿真结果表明,漏损故障时的混沌特性显著改变并能立即检测到,缓慢漏水2 h后混沌特性变化明显,为及时修补供水系统提供依据,减小了资源损耗。     

Time-dependent leak behavior of flawed Alloy 600 tube specimens at constant pressure

Leak rate testing has been performed using Alloy 600 tube specimens with throughwall flaws. Some specimens have shown time-dependent leak behavior at constant pressure conditions. Fractographic characterization was performed to identify the time-dependent crack growth mechanism. The fracture surface of the specimens showed the typical features of ductile fracture, as well as the distinct crystallographic facets, typical of fatigue crack growth at low ΔK level. Structural vibration appears to have been caused by the oscillation of pressure, induced by a high-pressure pump used in a test facility, and by the water jet/tube structure interaction. Analyses of the leak behaviors and crack growth indicated that both the high-pressure pump and the water jet could significantly contribute to fatigue crack growth. To determine whether the fatigue crack growth during the leak testing can occur solely by the water jet effect, leak rate tests at constant pressure without the high-pressure pump need to be performed.     

烧结机缝隙磁场密封模拟实验

为解决钢铁厂烧结机高漏风率问题,设计制作了缝隙磁场密封模拟装置,用钕铁硼永磁合金作为密封磁场源,模拟烧结机的缝隙状况进行了磁场密封实验。结果表明:在磁力作用下,密封介质被约束在缝隙中,形成了均匀致密的密封屏障,在15～300℃温度下,密封负压达到50 kPa。本磁场密封方法用于实际烧结机中,足以使所密封部位达到"0"漏风率。     

Thermal cycle stability of BaO–B2O3–SiO2 sealing glass

Thermal cycle stability is very important for glass seals in planar solid oxide fuel cell (pSOFC) applications. In the present study, thermal cycle stability of a thermally stable sealing glass is investigated using a sealing fixture from 150 °C to 700 °C. SS410 alloy with the TEC (thermal expansion coefficient) of 12.2 × 10⁻⁶ K⁻¹ (room temperature to 700 °C) is used to evaluate the effect of TEC mismatch on the thermal cycle stability. The leak rates increase with thermal cycles and appear to be two different stages. Microstructure examinations are performed to investigate the degradation mechanism of the thermal cycle stability. It is found that the sealing glass interacts chemically with the SS410 alloy and the formation of BaCrO₄ new phase results in the rapid increase of the leak rates.     

国外天然气管道检测技术现状及启示

中国天然气管道即将进入事故高发的老龄化阶段,如何高效进行管道检测成为亟待解决的问题。为此,在调研大量论文、研究报告和企业信息的基础上,围绕天然气管道可视化检测、管壁金属损失检测、泄漏检测和在线监测技术,对国外已成熟应用而国内正处于起步阶段的天然气管道检测技术进行了全面介绍,分析了该技术在我国应用所面临的主要障碍,并从检测功能、技术适应性、技术改进等方面总结了检测技术的发展方向。结论认为:(1)国外天然气管道检测技术主要针对腐蚀坑、缺陷、剩余壁厚和泄漏,很多技术都以管道机器人为载体,配合其他技术理论及多种传感器行使技术功能,管道检测的技术和设备必将朝着综合检测(检测多种数据)的方向发展;(2)国外天然气管道的部分检测技术仅可应用于小口径管道,对于大口径管道则具有一定的局限性,提高检测设备的适应性是必然趋势;(3)国外天然气管道检测技术在我国应用的难点主要体现在目前国内尚未形成检测技术实施和验收的标准体系,很多检测数据需要人为解释且暂时缺乏相关的专业培训;(4)自动解读数据成为管道检测的一个新兴发展方向,届时机器可自动识别管道内缺陷、腐蚀状况等参数并提供可靠性较高的检测报告;(5)提高检测设备的续航能力、数据存储能力和远传能力是检测技术改进的发展方向;(6)管道检测技术配套完整性管理平台的研发,能够促进天然气管道的智能化管理。     

一种网络空间中的数字基因身份识别方法

首先通过大量客观事实揭示出用户密码已经严重威胁到网络空间(Cyberspace)的信息安全,然后证明UP(Username,Password)在Cyberspace中作为身份识别的局限性,最后基于对信息网络空间的客观属性信息的研究,介绍了一种新的可信的网络身份标识系统—Cyber GeneID(GID)、俗称CFP(通信指纹),解决唯一可信身份识别问题。     

极小气体流量测量技术研究

介绍了固定流导法极小气体流量测量技术,利用流导值为10-9m3/s量级的精密小孔,通过在10-1~10 Pa范围内调节进气压力,实现了10-8~10-10Pa·m3/s的流量测量,合成标准不确定度为0.94%。利用流导比值为187.9的两个激光小孔,将固定流导法产生了流量分流为总流量的0.53%,实现了10-10~10-12Pa·m3/s范围内流量的测量,合成标准不确定度为1.2%。利用极小气体流量测量技术校准了小于10-8Pa·m3/s量级的真空漏孔,而且避免了四极质谱计的非线性引入的测量不确定度。与现有气体流量测量技术相比,提出的极小气体流量测量技术将测量下限延伸了4个数量级。     

Enhancement of leak rate estimation model for corroded cracked thin tubes

During the last couple of decades, lots of researches on structural integrity assessment and leak rate estimation have been carried out to prevent unanticipated catastrophic failures of pressure retaining nuclear components. However, from the standpoint of leakage integrity, there are still some arguments for predicting the leak rate of cracked components due primarily to uncertainties attached to various parameters in flow models. The purpose of present work is to suggest a leak rate estimation method for thin tubes with artificial cracks. In this context, 23 leak rate tests are carried out for laboratory generated stress corrosion cracked tube specimens subjected to internal pressure. Engineering equations to calculate crack opening displacements are developed from detailed three-dimensional elastic-plastic finite element analyses and then a simplified practical model is proposed based on the equations as well as test data. Verification of the proposed method is done through comparing leak rates and it will enable more reliable design and/or operation of thin tubes.     

Optimal pressure sensor placement and assessment for leak location using a relaxed isolation index: Application to the Barcelona water network

Water distribution networks are large complex systems affected by leaks, which often entail high costs and may severely jeopardise the overall water distribution performance. Successful leak location is paramount in order to minimize the impact of these leaks when occurring. Sensor placement is a key issue in the leak location process, since the overall performance and success of this process highly depends on the choice of the sensors gathering data from the network. Common problems when isolating leaks in large scale highly gridded real water distribution networks include leak mislabelling and the obtention of large number of possible leak locations. This is due to similarity of leak effect in the measurements, which may be caused by topological issues and led to incomplete coverage of the whole network. The sensor placement strategy may minimize these undesired effects by setting the sensor placement optimisation problem with the appropriate assumptions (e.g. geographically cluster alike leak behaviors) and by taking into account real aspects of the practical application, such as the acceptable leak location distance. In this paper, a sensor placement methodology considering these aspects and a general sensor distribution assessment method for leak diagnosis in water distribution systems is presented and exemplified with a small illustrative case study. Finally, the proposed method is applied to two real District Metered Areas (DMAs) located within the Barcelona water distribution network.