Flow Electrification of Insulated Liquid in Metal Pipes

When relative motion occurs between a liquid and a solid, the two phases carry electric charge with opposite signs. The created charge easily accumulates in the liquid, and the amount of the charge carried in an insulated liquid refers to many factors, such as contact area with the solid surface, the contact time, and so forth. However, current theories agree that the amount of charge created during flow electrification is proportional to the contact surface. In this paper, the classical wall current theory is applied to establish an interfacial electrical double-layer model of flow electrification phenomena when an insulated liquid passes over metal pipe surface. Meanwhile, in conjunction with charge relaxation function, the relation between the charge density and flow velocity, the contact time and the contact area is obtained during the liquid flowing process. The experimental result demonstrates that the flowing charge carried in the insulated liquid is not simply proportional to the contact area, but has a non-linear dependence on the contact area and the contact time. Moreover, down flow experimental equipment pipes of different length and diameter, and dielectric hydraulic oil VG46 are used in an experimental study of laminar flow, in order to understand electrification phenomena in dielectric liquid flowing over metal pipes of different length and aperture. If they both increase linearly, charge relaxation will increase exponentially. As a result, the test result verifies related theoretical analysis, and the method given provides a theoretical basis to analyze interracial electrical phenomena.

Influence Factors of the Generation and Accumulation of Electric Charge on the Oil-Delivery Metal Pipelines

The interfacial electrification properties play an important role in the electrochemical corrosion reaction which leads the electrostatic charge to generate and accumulate on the metal surface when the insulating oil flows through a metal pipe. In this paper, the interfacial electrification properties resulted by the oil flow rate and the action of electric charge trapper are investigated by measuring the current and potential on the surface of the test metal pipe. The measured results showed that the current and potential between the metal pipe and the earth increased with the rise of flow rate; and as the flow rate increased, the growth trends of the current and potential difference between two close flow rates increased and decreased, respectively, while there was an electric charge trapper set in the radial direction of the pipe, the measured current and potential decreased compared with that of without electric charge trapper, which was because it captured and caught part of charge in the oil flow bulk to neutralize the opposite charge on the surface of the metal pipe.

Discussion on New Evaluation Technology of Non-Metallic Composite Continuous Pipe for Oil and Gas Field

In view of the serious lack and lag of the test and evaluation technology of non-metallic composite continuous pipe, and focusing on the characteristics of the application of non-metallic composite continuous pipe in oil field, this paper discusses a series of new full-scale test and evaluation technologies for accurately evaluating the product quality and practical application performance of non-metallic composite continuous pipe, which effectively solves the major technical problem that the new products of non-metallic pipe cannot be accurately evaluated. Based on the characteristics of the application of non-metallic composite continuous pipe in oil field, a series of new full-scale test evaluation technologies which can accurately evaluate the product quality and practical application performance of non-metallic pipe are designed through a large number of tests. The test and evaluation technology can accurately evaluate the key performance of high and low pressure cycle, high and low temperature cycle, gas permeability resistance, minimum bending radius etc. It provides a scientific evaluation basis for the standardized application of non-metallic continuous pipe and a reliable quality control method for the selection of products in oil field.

弯曲载荷下双金属机械复合管内衬层屈曲失效机理

双金属机械复合管是油气田集输管线防腐控制的主要措施之一,而内衬层的失效是制约复合管工程应用的关键难题。为研究双金属机械复合管内衬层屈曲失效机理,建立弯曲载荷下复合管力学模型,研究成型压力、工作内压及复合管结构参数对内衬层失效模式的影响规律。结果表明:增加成型后的残余接触压力有助于提高内衬层的抗屈曲能力;较高的工作内压能够延缓内衬层屈曲时间,减小其褶皱幅值;成型前复合管层间初始间隙减小有利于提高内衬层抗屈曲能力;随着外基管壁厚、内衬管壁厚、复合管内径的增加,内衬管的抗屈曲能力增强。

变电站周围管网及新建地网系统对原接地网特性参数的影响

“双碳”目标的大背景下,随着以高比例新能源为主体的新型电力系统的建设,原变电站接地网已然难以满足当下需求,存在着新改造地网与老旧地网的安全运行问题以及周围地下金属管网的接入使改造地网产生的参数变动问题。接地网的某项参数不达标,则会影响变电站和站内设备的稳定运行,对人身安全造成严重的影响。因此,需要分析改建地网及金属管网等原变电站周围管网系统参数指标的安全限值,综合考虑分层土壤结构、地下金属管网及其他周围地形对于改建地网安全运行的影响效应。基于矩量法并结合CDEGS接地网仿真软件搭建了新旧地网以及周边金属管道数学模型,综合考虑各种土壤特性下变电站周围金属管道以及新建地网对原变电站的各个特性参数,进行了分析研究,获得了多种情况下变电站接地网与金属管道以及原接地网与新建地网之间的阻性耦合影响曲线及各项接地参数的对比,并据此提出相应的防护措施。实验发现:对金属管道敷设绝缘层可以有效减小管道的散流作用,但对降低接触电压并不明显,敷设绝缘层前后接触电压仅下降3%;将新建地网与原接地网相连使原变电站接地网最大接触电压下降28.1%,降阻率达20%。为变电站接地网改造工程及新型电力系统的构建提供一定的理论依据。

基于多物理耦合的高温热管流动传热和力学特性研究

研究高温碱金属热管内工质的流动、传热和力学特性,对热管冷却反应堆的安全具有重要意义。本文采用COMSOL Multiphysics有限元软件构建了高温碱金属热管的多物理耦合模型,针对热管内工质的流动传热特性以及管壁的热膨胀效应进行了数值模拟研究。结果表明:本文模型的计算结果与实验值的相对误差小于1%,可准确模拟高温热管的流动传热特性;在额定功率下,沿轴向的压力梯度和温度梯度较小,说明热管具有较好的等温性,但相比于冷态有最大1.75%的总形变;热管的传输功率提高会显著影响热管内工质的运行状态,同时加大热管的形变量。

油气田地面集输管线选材

介绍了碳钢、低合金钢、金属复合管、聚乙烯管、钢骨架增强聚乙烯复合管、高压柔性复合管等油气田地面集输管材的结构特点、尺寸边界、连接形式及应用场景限制。给出了油气田地面集输管线的选材原则,从标准、腐蚀模型分析及室内模拟评价试验对管线腐蚀程度预判做了详细介绍。根据管材的适用范围及地面集输管材的选用原则,对常规工况、含二氧化碳工况、含硫化氢工况和含二氧化碳/硫化氢工况等四种典型工况下的管材选取进行了推荐。

金属长滤袋脉冲喷吹清灰均匀性优化研究

为了探究喷吹管的喷吹孔径分布方式对金属长滤袋脉冲喷吹清灰均匀性的影响,采用3种喷吹孔径分布方式不同的喷吹管对金属长滤袋进行脉冲喷吹实验,对比研究不同喷吹孔径分布方式下,沿喷吹管气流方向滤袋间侧壁压力峰值分布规律。结果表明:采用喷吹管T_(1)时,滤袋侧壁压力峰值沿喷吹孔K_(1)—K_(9)方向分布不均匀,波动幅度较大,不满足清灰均匀性的要求;采用喷吹管T_(2)时,滤袋清灰均匀性有所改善,但仍不满足清灰均匀性的要求;采用喷吹管T_(3),喷吹孔K_(1)—K_(9)对应滤袋侧壁压力峰值变化趋势平缓,各测点侧壁压力峰值的方差均小于0.01,表明喷吹管T_(3)满足金属长滤袋清灰均匀性的要求。结果表明可以采用改变喷吹管孔径及其分布方式提高金属长滤袋脉冲喷吹的清灰均匀性。

金属膜过滤工艺保障不同管材供水管网水质生物稳定性的研究

供水管网末梢水水质生物安全问题受到了广泛关注。采用生物膜环状反应器(BAR)模拟实际供水管网,探究了自来水和金属膜滤后水(膜滤水)对5种管材管壁生物膜影响的异同性。结果表明,金属膜过滤工艺对水中浑浊度、溶解性有机碳的平均去除率分别为93.4%、19.0%;5种管材管壁生物膜在生长稳定期的生物量排序为铜<不锈钢≈聚氯乙烯(PVC)≈高密度聚乙烯(HDPE)<球墨铸铁;自来水体系中反应器进出水平均浑浊度分别为1.52、3.44 NTU,而膜滤水体系反应器进出水平均浑浊度分别为0.10、0.42 NTU,且各管材管壁生物膜生长缓慢。这是因为膜滤水体系微生物群落物种丰富度较低,管壁生物膜样品的OTU数减少了39.7%~56.5%,耐氯致病菌(分枝杆菌、甲基杆菌等)相对丰度明显减少。因此,金属膜过滤工艺可有效保障供水管网饮用水水质生物稳定性。

地埋金属管材阴极屏蔽防腐失效研究

目前解决地埋金属管材腐蚀问题最常用和最有效的方法是对金属管材进行表面涂层处理,常用的有机涂料存在耐腐蚀性随涂层老化而快速下降的缺点。依托随州管廊项目,通过对管廊内金属设备防腐层进行分析,得到防腐涂层的失效原因,分析阴极保护体系下阴极屏蔽的产生原因,选出合理的涂层施工技术,减少防腐涂层施工中的污染来源,为类似项目提供参考。

离子膜电解槽的金属出料总管更换总结

因电解槽阳极出料总管出现明显腐蚀,进行更换。给出更换电解槽出料总管的制作技术要求、安装要求和现场运行情况。针对运行中出现的问题,制定出改进措施,消除了电解槽运行的安全隐患,保证装置长周期安全、稳定运行。

波纹管涵在公路设计和施工中的应用分析

西南地区高速公路建设往往受地理条件的限制,采用传统的钢筋混凝土盖板涵和箱涵,往往施工周期长、造价高。近年来,随着新材料技术的不断发展,以及装配式施工理念的推广,金属波纹管作为一种新型环保材料,在施工、安装、造价等方面都具有较好的优势,目前在高速公路建设中进行了较好的推广。对金属波纹管涵的优点进行了分析,研究其在高速公路涵洞设计及施工实践中的运用,并以贵州高速公路涵洞设计为例进行分析论证,结果表明,金属波纹管涵节省投资、缩短工期、安装更便捷、环保。

金属磁记忆技术对绝缘接头定位检测的应用

由于管道建设历史久远,部分管道存在资料缺失,导致绝缘接头的埋设位置难以确定;本文利用金属磁记忆检测方法,通过检测埋地管道上方地表磁记忆信号变化特征,在不开挖的情况下快速确定了绝缘接头的埋设位置。

埋地高压电缆与金属管道邻近敷设时电磁影响模型及计算方法

高压电缆线路对邻近金属管道的电磁影响问题关系到金属管道的安全稳定运行,是城区电缆线路设计时必须考虑的问题之一。但是,由于土壤结构、电缆和管道结构的复杂性,尚缺乏有效的电磁影响建模和计算手段。基于多导体传输线理论,建立了埋地三相电缆与金属管道邻近敷设时的电磁影响分析模型,阐述了其单位长阻抗矩阵和导纳矩阵的计算方法。针对存在公共接地阻抗的诺顿等效和戴维南等效端口情况,提出了基于级联参数矩阵的金属管道和电缆屏蔽层感应电压的计算方法,并拓展至三相电缆交叉互联以及电缆与金属管道交叉跨越、斜向接近的复杂情况,并可以考虑电缆短路故障的影响。通过算例,验证了建模方法和计算方法的有效性。研究结果为邻近金属管道时埋地电力电缆线路的设计提供了技术手段。

Heat Transport Study of the Laminar Heat Pipe Heat Exchanger

The purpose of this experiment is to analyze the performance of the Laminar Heat Pipe Heat Exchanger. The test samples were divided two groups, one is the metal corrugated sheet with heat pipe, and the other is the metal corrugated sheet only. By dipping these two group samples into hot water and to see the thermal image by Infrared thermal imager. The results shown the temperature risen of the sheet with heat pipe was faster than that of the sheet without heat pipe. In addition, the bigger of the temperature difference between hot water temperature and ambient temperature, the quicker of the temperature risen for the metal corrugated sheet, and the temperature of the metal corrugated sheet were homogenous as well. For example, when the water temperature is 30℃, ambient temperature is 20℃, the metal corrugated sheet with heat pipe rise rapidly to 26℃ within 1 minute, while the metal corrugated sheet without heat pipe rise to 22℃ only, this temperature difference would be more obvious with the increasing of the hot water temperature. When the hot water temperature is up to 40℃, the metal corrugated sheet with heat pipe rise rapidly to 31℃ within 1 minute, while the metal corrugated sheet without het pipe is still rise up to 22℃ only. When the hot water temperature is up to 50℃, The metal corrugated sheet with heat pipe rise rapidly to 33℃ within 1 minute, while the sheet without heat pipe still keep at 22℃, the results shown the heat pipe affect the temperature rising speed is obvious, and it also implying heat pipe is a very important parameter for the heat transfer rate of the Laminar Heat Pipe Heat Exchanger.

Kinetics of Acicular Ferrite Transformation in Weld Metal

Acicular Ferrite(AF) is beneficial in welds because it provides a tough and strong microstructure.Therefore,much works have been done in the study of the effect of alloying elements and welding conditions aimed at obtaining more AF in the weld metal.However,the knowledge about the nature of AF is limited due to the lack of kinetics researches.In this paper,the kinetic curves of AF transformation in an X65 weld metal were established by means of welding thermal simulation test.The results showed that AF transformation is a typical diffusion process of nucleation and growth with incubation period.AF transformation in weld metal obeys the relationship described by JMA Equation.The effect of welding heat input was also studied.

油田集输化学药剂对国产HDPE适用性的影响

为研究油田集输化学药剂对DQDN3711型聚乙烯内衬材料适用性的影响,采用高温高压反应釜挂片实验模拟长庆油田投加药剂环境,分析添加缓蚀阻垢剂、破乳剂后,DQDN3711型聚乙烯在采出原油和采出水介质中的相容性。研究结果表明,缓释阻垢剂、破乳剂、采出原油与采出水均能渗透、扩散进入聚乙烯,使其发生溶胀,聚乙烯的最大增重率为1.82%,屈服强度、拉断强度、断裂伸长率最大变化率分别为-6.37%、-11.79%、-13.15%,冲击强度最大变化率为-9.59%,材料的性能均能满足ISO 23936—1—2009要求;缓释阻垢剂、破乳剂阻碍了集输介质渗透作用,HDPE体积增长率显著降低,采出水中药剂对HDPE的渗透大于采出油。综上所述,在油田集输加剂工况下,国产DQDN3711型HDPE适用性较好。

Motion behavior of non-metallic particles under high frequency magnetic field

Non-metallic particles, especially alumina, are the main inclusions in aluminum and its alloys. Numerical simulation and the corresponding experiments were carried out to study the motion behavior of alumina particles in commercial pure aluminum under high frequency magnetic field. At the meantime, multi-pipe experiment was also done to discuss the prospect of continuous elimination of non-metallic particles under high frequency magnetic field. It is shown that: 1) results of numerical simulation are in good agreement with the experimental results, which certificates the rationality of the simulation model; 2) when the intensity of high frequency magnetic field is 0.06 T, the 30 μm alumina particles in melt inner could migrate to the edge and be removed within 2 s; 3) multi-pipe elimination of alumina particles under high frequency magnetic field is also effective and has a good prospect in industrial application.

TO56金属管帽多工位级进模设计

根据TO56金属管帽的结构特点,分析了制件的结构工艺性,计算制件的工艺参数,拟定制件的工艺路线,并针对首次拉深成形开展有限元分析;在此基础上完成拉深、冲孔、切边等关键工序的工位结构设计,设计了该制件多工位级进模的整体结构。

海洋平台金属管线安装质量控制要点

金属管线作为海洋平台的关键组成部分,其安装过程中的质量控制工作成功与否直接决定了海洋平台是否能健康、安全服役。文章结合多年的工程实践经验结合管线安装过程中出现的典型问题,从清洁施工、材料储存、安装、压力试验、清洁、复位等环节,具体阐述了质量控制要点,为海洋平台金属管线安装过程中的质量控制工作提供指导。