Improving the reliability of multiplexed fiber optic low-coherence interferometric sensors by use of novel twin-loop network topologies

Novel twin-loop network topologies for multiplexing fiber optic low-coherence reflectometric sensors are proposed and theoretically analyzed. The sensing fibers are made by connecting segments of standard single-mode fibers with partial reflections at the fiber joints and are completely passive. Absolute length measurement can be made for each segment of the sensing fiber so that strain or temperature distribution along the entire sensing fiber can be derived. It is expected that novel topologies would help as to improve the reliability of the sensor network by providing multiple accesses to each of the sensing segment so that most of the sensing segments can still be interrogated even when one or more point breakages occur along the transmission fibers. A nine-sensor twin-loop sensing network was constructed and experimentally tested by use of a Michelson low-coherence interferometer, and the results obtained agree with our theoretical prediction. The novel network topologies may be used for large-scale smart structure applications where breakages of transmission fibers may occur during the stages of sensor imbedding, installation, and structure-in-service cycles.     

原油储罐油量动态计量技术研究

为了比较精确地计量原油储罐的动态油量,在分析研究油罐液位、油水界面、原油含水率、密度以及温度测量的基础上,重点讨论测量中的含水率测量不确定度和净油质量测量的不确定度,分析了引起测量误差的主要原因。通过现场实例提出储罐油量的计量方案和解决在线监测过程中产生误差的实用方法。实验结果表明,所提出的设计方案和解决误差的方法可用于油田联合站和油库罐区动态油量的计量或自动化盘库。     

大型液化天然气储罐的发展研究

世界能源日益紧张,天然气在世界能源结构中的比重将赶超石油成为世界第一大能源.到目前为止我国尚无大型液化天然气贮罐国家标准,也无自行设计、建造的大型液化天然气储罐,也未掌握液化天然气核心技术,因此加强对液化天然气储罐的研究对推动我国液化天然气工业的发展,解决日益恶化的环境问题和能源危机都具有十分重要的现实意义.简述了液化天然气的优点,按照不同的分类依据对液化天然气储罐进行了分类,结合国内外液化天然气储罐的建造状况对其进行了分析,并提出了液化天然气储罐大型化的发展趋势,对于液化天然气储罐的研究和工程应用具有一定的参考价值.     

关于我国球罐技术精细化的几点思考

近年来,我国球罐技术取得了较大进步,很多大型高参数球罐已实现了国产化,但要做到从有到精还有一定差距。结合目前的技术状况,从存储工艺对设备的技术经济影响、采纳先进设计技术理念、强化球罐材料专用化配套开发,以及完善制造、安装、检验的细节技术等方面,讨论了球罐技术向精细化发展的要点。对今后球罐研究工作及提高建造技术水平都有一定的指导作用。     

太阳能空调用多级水箱蓄热系统特性研究

介绍一种用于太阳能空调系统的多级水箱蓄热系统,在对其进行了理论分析的基础上,借助搭建的多级水箱蓄热试验装置,对不同级数系统的性能进行了试验研究。结果表明:随着多级水箱蓄热系统级数的增多,第一级蓄热水箱完成蓄热耗时变短,蓄热量品位逐步提高;在蓄热过程中系统级数越多,理想供热进口水温工作时间越长,但放热过程中情况与之相反。据此提出了系统的优化改进方案,优化改进后的系统对理想供热进口水温工作时间的延长效果明显。     

基于Zigbee无线传感器网络的水环境监测系统

针对现有有线水环境监测系统布线困难、成本高、监测水域范围受限制等问题,设计了一种基于Zigbee无线传感器网络的水环境监测系统。该系统以Zigbee无线传感器网络和3G网络为核心,通过布置在监测水域的传感器节点进行数据采集,多个传感器节点构成1个无线网络,网关节点负责数据收集并通过3G网络传输给远程数据管理中心。实验表明:系统构建简单,工作稳定可靠,适应于大范围的水环境实时监测。     

非正交FBG柔杆空间形状重构误差分析及标定

为了提高FBG柔杆空间形状感知系统的重构精度,提出了一种利用3根FBG阵列、具有温度补偿特性的非正交FBG柔杆检测方法。在分析传感系统的误差组成、产生原因的基础上,建立仿真模型得到了各组成误差分别对系统空间形状重构精度的影响,得出减小安装角度误差是提升精度的关键。利用待标定参数与标定方向与实际检测方向夹角大小相关的原理,给出了一种修正安装角度误差的标定方法。经过实验证明,该方法使得系统形状重构最大相对误差降为0.25%,为高精度的三维形状感知系统提供了可靠的检测方法。     

Void fraction measurement of gas–liquid two-phase flow from differential pressure

Void fraction is an important process variable for the volume and mass computation required for transportation of gas–liquid mixture in pipelines, storage in tanks, metering and custody transfer. Inaccurate measurement would introduce errors in product measurement with potentials for loss of revenue. Accurate measurement is often constrained by invasive and expensive online measurement techniques. This work focuses on the use of cost effective and non-invasive pressure sensors to calculate the gas void fraction of gas–liquid flow. The differential pressure readings from the vertical upward bubbly and slug air–water flow are substituted into classical mathematical models based on energy conservation to derive the void fraction. Electrical Resistance Tomography (ERT) and Wire-mesh Sensor (WMS) are used as benchmark to validate the void fraction obtained from the differential pressure. Consequently the model is able to produce reasonable agreement with ERT and WMS on the void fraction measurement. The effect of the friction loss on the mathematical models is also investigated and discussed. It is concluded the friction loss cannot be neglected, particularly when gas void fraction is less than 0.2.     

HTG系统液位测量误差分析与修正

本文首先以静压式油罐计量系统（ＨＴＧ）原理作了简单介绍,然后指出导致该方法液位测量误差偏大的主要原因是温度和压力,最后详细讨论 度与压力各自对液位测量误差的影响,文末给出了修正公正,对于理解大型油罐中普遍存在的密度分层现象有重要意义。     

SAAB雷达液位计在液化石油气储罐上的应用

随着石化工业的进步,低精度、接触型的液位测量仪已经不能满足液化石油气储罐的要求。针对这种状况,大连石化公司储运车间球罐区使用ROSEMOUNT公司的SAAB雷达液位计测量储罐的液位等参数。本文就RTG3960液位计的结构、原理、参数设定等方面作了详细的介绍。该液位仪以其高自动化集成、高精度、高可靠性等优点,在石化行业中得到了广泛的应用,并取得了良好的经济效益和社会效益。     

Development of liquid level measurement technology: A review

Depending on various applications, the process control industry uses liquid-level sensors of different principles. Due to the dynamic nature of liquid such as water, wastewater, petroleum etc., and characteristic of storage tank, the measurement is difficult and it violate the accurate measurement. Instances of level measurement and control failure lead to tragic and costly consequences. Selecting the accurate level measurement technique for a particular application is a daunting task in the face of many options and limitations. Hence, this paper reviews liquid level measuring instruments used in the past 11 years. Both the contact and non-contact measurement are discussed, and their development on measuring liquid level is also covered in this review paper. From the study, it is clear that ultrasonic sensors are most widely used for liquid level measurement with high accuracy while neglecting the drawback of the echo inside the tank.     

Application and uncertainty analysis of a balance weighing system used in natural gas primary standard up to 60 bar

A new 3-ton balance weighing system was designed and built up for a high level mass-time primary standard of natural gas up to 60 bar in CVB. The system is composed of a 3-ton electromagnetic balance, two tanks with thermal isolation, two platforms, two roller guide rails and two big weights which are used for special test. To achieve a lower uncertainty and the security application in natural gas measurement, several special methods were used in the system. Firstly, the tanks and platforms can be moved together steadily on the roller guide rail to be connected with pipeline system or to be weighted by the balance which also reduces the pipeline length between tanks and pipeline system. Secondly, the substitute weighing method is used for high accurate weighing. Finally, the whole system is located in a thermal isolated room with temperature and humidity controlling. Technical details, performance tests, uncertainty analysis and the future improvement ideas of the balance system are presented in the paper. The uncertainty analysis shows that the mass measurement uncertainty of gas can achieve less than 1.0g and the maximum relative standard uncertainty of natural gas mass measurement would be no more than 0.022%.     

基于CAN总线的船舶油舱分布式液位实时监测系统设计

文中根据远洋船舶油舱分布的具体特点，提出了基于CAN总线的油舱液位监测系统实施方案，该方案综合应用了PC机、单片机及CAN总线的优点，在较低成本下实现了对各个船舱油舱液位的实时测量与监控，并且系统具有较高的可靠性和可维护性。介绍了系统工作原理、拓扑结构及软硬件实现。     

Design of a Conductance and Capacitance Combination Sensor for water holdup measurement in oil–water two-phase flow

Oil–water two-phase flow widely exists in the process of petroleum industry. The liquid holdup measurement in horizontal pipeline is very important and difficult. In this work, a Conductance and Capacitance Combination Sensor (CCCS) system with four conductance rings and two concave capacitance plates is designed and validated for its measurement performance of in situ water holdup through dynamic experiments. A set of fast electronic switches controls the conductance rings and the capacitance plates alternatively set up each own sensing field in the same sensing volume. This configuration ensures the water holdup estimation in the range from 0% to 100% regardless of flow direction. A set of quick closing valves was used to acquire the in situ holdup for the on-line calibration of the CCCS system. The theoretical correlations of conductance sensor and capacitance sensor were established to make the real-time measurement convenient. A real-time measurement method by CCCS system is provided based on the fusion of the conductance and the capacitance measurement without flow pattern recognition. This method delivers an average error of 1.06% for the CCCS system measuring the water holdup of oil–water two-phase flow, with a standard deviation of 0.038 and a relative error less than ±5%.     

Design and analysis of flow measurement of conductive liquid and transmission via optical channel

Measurement and transmission of flow rate of a conducting liquid through a pipe line is generally done by using electromagnetic flow meter which consists of a large electromagnet and a pair of sensing electrodes along with electronic system and involves large cost and size. In the present paper, a very simple flow sensing system for a conducting liquid is proposed and this system does not require any electromagnet and involves very low cost. Moreover in modern instrumentation system the signal transmission through optical communication system is being more preferred where the transmitted signal does not suffer from measurement error due to electromagnetic interference. So an MZI based optical communication technique has been described in the present paper. The proposed technique consists of only four insulated conducting electrodes in contact with the flowing liquid along with an electro-optic system for signal conditioning and transmission of the measured signal to a remote location. The performance of the sensor and the transmission system has been analyzed in the form of a bridge network with bridge arms represented by lumped parameter polarization impedances among the electrodes. The theoretical equations explaining the operation of the bridge network with a stabilized sinusoidal ac source and MZI based electro-optic system have been derived. A proto type unit has been designed, fabricated and its function has been studied experimentally and the experimental results are reported in the paper. A very good linear characteristic under streamline condition of the proposed unit has been observed with very good repeatability and very small uncertainty of measurement. The graphical abstract is shown below.     

射频导纳技术在蒸发器液位测量中的应用

针对海水淡化蒸发器运行工况复杂、结构设计紧凑、液位测量范围小、常规差压法安装困难等问题,提出了一种利用射频导纳技术测量蒸发器液位的方法。重点对射频导纳液位计的工作原理、主要特点、电极选型、安装注意事项以及标定方法进行了阐述和探讨,并在30t/d LT-MED中试装置中成功应用。结果表明:该仪表安装简单、测量准确、维护方便且适用范围较广,具有很好的应用前景。     

高炉冷却系统热负荷在线监测系统

本文详细地叙述了系统的组成、工作原理和功能。温度、流量检测采用自行设计的采集装置,成本低,安装简便,可靠性高,满足了测量要求。采用该监测系统可实时地监测高炉冷却系统的水温差、流量及热负荷,为高炉安全生产提供依据。     

差压仪表在球罐液位测量中的深化应用

通过对早期LPG球罐液位改造的介绍，讲述不同方式的差压仪表在球罐液位测量上的运用，剖析了各种方式产生误差的主要根源，提出了一种以Emerson 3051S ERS与温度补偿相结合的解决方案，为大量程的液位测量提供一条高精度的简便办法。     

Micron Resolution Electromechanical Liquid Level Measurement System

Abstract

A new electromechanical liquid‐level measurement system, able to achieve measurements on micron sensitivity, is presented in this study. A simple stepping motor provides vertical movements to electrodes sensing the water level. A microcontroller installed on the system determines the number of steps executed by the motor when electrodes move between an upper reference plane and the level of the liquid to be measured below the reference plane. This number is transformed, by the micro‐controller, to the depth of the liquid level relative to the reference plane. The system is particularly useful for the detection of liquid level changes. The level sensor can be used, not only for precise water level measurements, but also for other non‐explosive and non‐flammable liquids and for conductive solid surfaces. Besides this, changes in water levels in natural lakes and in dam lakes, and fluctuations of the groundwater in wells can be sensitively detected by this sensor.     

门座起重机网络安全监控管理系统

根据门座起重机安全监控需要,设计了一种基于新型传感技术、黑匣子数据存储技术和无线数传技术相结合的门座起重机网络安全监控管理系统。依据国家标准和客户要求,实现了起重机安全运行信息的实时采集、存储和远程传输,设计了设备网络化管理软件,实现了用户对大型起重机械设备的远程监管。