气泡对电磁流量测量的影响特性研究

电磁流量计在工业生产过程中扮演着重要角色,但易受流体中气泡的影响导致测量结果出现波动进而影响测量精度。定量分析气泡在电磁流量计测量过程中产生影响的规律对提高电磁流量测量精度和实现气液两相流测量具有重要工程意义。针对上述问题,首先从权重函数角度入手,采用解析法建立了气泡尺寸、气泡偏心以及气泡数量对电磁流量测量影响的理论模型;其次,通过仿真和实验研究了管径为100 mm,圆形点电极半径为5 mm的电磁流量系统受气泡不同状态的影响,并采用输出电压灵敏度分析了气泡不同状态下对电磁流量测量的影响规律。研究结果表明,随着气泡尺寸增加其影响大小随之增加,气泡尺寸变化过程中影响在0.3%~5%范围内变化,最大为5%;气泡(直径为10 mm)沿电极方向偏心产生的影响在0.25%~0.6%范围内,且随偏心距离的增加而增加;气泡沿垂直电极方向偏心距离增加产生的影响微小,在-0.2%~0.2%范围内波动;同时,在气泡流动过程中,气泡越靠近电极截面影响越大并在电极截面位置产生影响最大值,单气泡最大值分别为0.18%、0.22%、-0.20%,随着气泡数量增加产生的影响逐渐增加,3气泡和6气泡影响最大值分别为0.36%和2.3%。本研究补充和完善了电磁法测量气液两相流权重函数相关理论,得出气液两相流中气泡不同状态对电磁流量测量系统的影响规律,为提高电磁流量测量检测精度和实现气液两相流电磁测量提供技术支持。

基于时域叠加的声学埋地PE管道定位新方法

聚乙烯(PE)管道凭借耐腐蚀、使用年限长等优点在城镇中、低压埋地燃气管网建设中被广泛应用,但由于管道信息系统不完善,且已有的埋地PE管道定位技术还不成熟,导致管道位置不明确,易造成施工建设中对管道的损伤和破坏。为此,基于弹性波反射原理,建立了弹性波在土壤—PE管道介质中的传播理论模型,提出了基于时域叠加的埋地PE管道定位新方法,并通过有限元仿真分析和现场管道定位测试验证了该定位方法的可行性。研究结果表明:(1)土壤中传播的声波可分为纵波和横波,其在土壤—PE管道分界面将发生反射、透射以及波形转换,其中反射回地面的弹性波含有地下管道位置信息,因此可利用反射回波信号来定位埋地PE管道;(2)使用时域叠加法对仿真得到的6路检波器信号进行处理并对定位区域成像,由成像图可较准确地定位出埋地PE管道,图中颜色最亮的单元几何中心点表示的是埋地PE管道的顶点;(3)分别进行了埋深为0.5 m、1.0 m、1.5 m的PE管道定位测试,最大定位误差依次为0.090 m、0.243 m、0.304 m,即管道埋深越大,定位误差越大。结论认为,该方法计算得到的定位精度可以满足现场定位埋地PE管道的需要,研究成果可用于指导声学埋地PE管道探测定位装备的研发。

Current Trends and Perspectives of Detection and Location for Buried Non-Metallic Pipelines

Buried pipelines are an essential component of the urban infrastructure of modern cities.Traditional buried pipes are mainly made of metal materials.With the development of material science and technology in recent years,non-metallic pipes,such as plastic pipes,ceramic pipes,and concrete pipes,are increasingly taking the place of pipes made from metal in various pipeline networks such as water supply,drainage,heat,industry,oil,and gas.The location technologies for the location of the buried metal pipeline have become mature,but detection and location technologies for the non-metallic pipelines are still developing.In this paper,current trends and future perspectives of detection and location of buried non-metallic pipelines are summarized.Initially,this paper reviews and analyzes electromagnetic induction technologies,electromagnetic wave technologies,and other physics-based technologies.It then focuses on acoustic detection and location technologies,and finally introduces emerging technologies.Then the technical characteristics of each detection and location method have been compared,with their strengths and weaknesses identified.The current trends and future perspectives of each buried non-metallic pipeline detection and location technology have also been defined.Finally,some suggestions for the future development of buried non-metallic pipeline detection and location technologies are provided.