天然气流量计量仪表现状及发展探讨

随着我国对天然气资源的需求量不断上升，天然气在我国能源结构中比重不断增加。天然气流量的准确计量是开展贸易的重要依据，也是企业优化资源量配置、提高天然气生产效率的重要依据。新时期天然气计量朝着智能化、自动化、远程化、能量计量、量值溯源由静态单参数变为动态多参数等方向发展，对于进一步降低企业生产成本、提升计量效率、提高企业经济效益具有重要意义。     

天然气的流量计算在智能孔板流量积算仪中的实现

对于天然气计量用的智能孔板流量积算仪，流量的计算方法对计量结果有非常重要的意义。而天然气的流量计算涉及参数多，计算过程复杂，选择合理的计算方法，不仅能够满足实时计算的要求，同时又能实现计算的精确性。从天然气流量计算的数学模型入手，充分利用单片机的现有资源，提出一种适用于智能孔板流量积算仪的天然气流量计算方法，并成功运用于所开发的积算仪中。经过实践检验，该方法满足了标准孔板流量计计量系统对准确度的要求。     

天然气孔板流量计的不确定度分析

目前天然气计量己制定了许多相关的国家标准、行业标准和计量检定规程等,但未形成完整体系,与国外相比尚有较大差距。本文着重探讨了天然气孔板流量测量中准确度要求和不确定度,分析了影响测量不确定度的几种因素。     

应用气相色谱法在线检测甲醇裂解气成分

应用气相色谱法对机载甲醇裂解气的成分进行在线检测,详细讲述气相色谱仪的工作原理以及色谱仪应用的配置和各种参数的设定,深入研究了解甲醇裂解气成分以及各成分含量对发动机性能的影响.     

Sick流量计算机的研究与应用

从德国Sick流量计算机的软件框架、参数变量表和Modbus点表几部分详细阐述工业Sick天然气流量计算机的使用方法和设置过程。设备支持远程本地设置采集和远程Web发布,依据AGA8-92DC实现天然气压缩因子计算,依据AGA10-2003计算天然气声速计算。流量计算机可以有效的计算天然气物性参数、临界流系数、等熵指数和定压比热容等天然气热力学参数和多通道超声波气体流量计的声速和误码率采集,同时设备支持上述所有配置参数和计算结果的Modbus数据采集。经测试,德国Sick流量计算机可以准确的实现天然气流量计量,并可靠的将数据通过Modbus传至后端PLC或组态软件,达到预期的使用效果。     

SGQ标准孔板流量核查系统在天然气流量计量上的应用

本文介绍了标准孔板流量核查系统的工作原理、安装和参数设置要求、系统功能及其在天然气计量上的应用情况,阐明标准孔板流量核查系统在天然气计量上的应用的可行性。     

天然气流量积算仪的软件设计

天然气的计量都以标准状态体积流量和质量流量计算,各测量工况下的流量必须折算为标准状态的体积或质量流量.其折算系数和诸多因素有关,因此必须根据测量条件下的温度、压力进行补偿,本文介绍了天然气流量测量修正系数三维数据表的建立、数据插入方法和查表程序的软件设计,该软件在天然气流量积算仪中得到有效的应用,取得了良好的效果.     

基于槽式孔板的凝析天然气计量技术

介绍了一种新型气液两相流量传感器——槽式孔板的结构特点和工作原理，并将其应用于凝析天然气计量技术研究。结合实验数据和理论模型详细分析了影响槽式孔板两相压降倍率的各种因素，利用曲面拟合技术给出了传感器两相压降倍率与压力、气体富劳德准数、Lockhart-Martinelli参数之间的相关式，该相关式计算精度可以满足生产计量的精度要求，为低含液率的凝析天然气流量计研制奠定了基础。     

计量及分析仪系统在天然气管线中的应用

介绍了在天然气计量中体积计量及能量计量两种不同的计量方式,以及在能量计量方式中流量及分析仪系统的作用、组成等内容,同时对天然气流量计的实流标定做了介绍.     

天然气常规分析中H2S气体的消除

天然气中含硫化氢组份会对采用气相色谱法分析天然气常规组分产生影响,采用Ｚｎ（ＡＣ）２溶液直接吸收法,能够彻底消除样品中的硫化氢气体,并且不影响其它组份的定量,该方法还可对天然气中的硫化氢组份进行粗定量。     

Uncertainty analysis of energy measurements in natural gas transmission networks

The value of natural gas depends on the energy obtainable from its combustion. Despite this, natural gas measurement and billing are normally performed using volume measurements subsequently converted into base conditions. Thus, to correctly achieve network balancing and accurate billings, both civil and industrial natural gas consumptions should be measured in energy. Unfortunately, energy measurements for natural gas are actually possible only in an indirect way by means of complex measurement chains with a flow-meter, a volume conversion device and a gas chromatograph or gas analyzer. Moreover, for technical and economic reasons, gas quality is often considered as constant and known despite the unavoidable variations due to the mixing of gases from different origins and type (i.e. importations, national productions, liquefied, biogas).In this paper the authors present the results of a detailed metrological experimental analysis of the typical energy measurement plants installed in natural gas networks. Modern networks are characterized by a wide variety of flow-rate measurement principles, constructive technologies and plant configurations. Therefore, flow regimes, thermodynamic conditions and chemical properties of the gas play a crucial role in determining metrological performance of natural gas energy measurements and uncertainties can become critical for inaccurate billing and unaccounted for gas.     

浅谈天然气计量

介绍陕西省天然气有限责任公司天然气计量的情况,提出了提高天然气计量的方法。     

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%.     

累积取样系统在城市燃气行业的应用研究

天然气的组成分析需要以取样为基础。目前,基于在线气相色谱仪的直接取样技术,以及基于累积取样系统的间接取样技术,已在国外天然气贸易交接中,获得了广泛应用。本文以北京燃气集团某门站的试验数据为基础,对比了分别采用在线气相色谱仪和累积取样系统分析获得的燃气物性参数。结果表明,通过上述两种方式获得的数据具有高度的一致性。在城市燃气行业,累积取样系统的应用,是对在线取样技术的有效补充。     

Particle image velocimetry flowmeter for natural gas applications

Ultrasonic flowmeters are currently used in the measurement of large natural gas flow. However, their high sensitivity to noise signals can cause measurement errors and direct economic losses. Particle image velocimetry (PIV) measurement technology has several advantages, including convenient installation and maintenance, and strong anti-interference ability, thereby presenting an innovative idea for its application in the field of flow measurement. In this paper, a cyclic integration method is proposed for the application of PIV technology in flow measurement of natural gas. The results show that PIV flowmeter and ultrasonic flowmeter are basically consistent, and the maximum deviation is about 2%. confirming the feasibility of the PIV flowmeter. Therefore, this study provides a theoretical and technical reference for the development of a PIV flowmeter for natural gas.     

节流阀内天然气组分凝结规律研究

节流制冷低温分离工艺是天然气集输过程中常见的脱水脱烃技术,节流凝结过程是天然气露点温度能否达标、工艺系统能否优化运行的关键。基于天然气在节流阀内的凝结过程,建立均质凝结和异质凝结统一的数值模型,研究天然气中易发生凝结的四种烷烃(正戊烷、正己烷、正庚烷、正辛烷)组分的凝结规律,分析背压比和总温等因素对凝结性质的影响。结果表明:节流阀内部流场非常复杂,呈现强湍流特性,节流孔内达到极低的温度使烃类组分的凝结在节流孔出口前基本完成。背压比和总温增加会减弱节流温降,使各组分的凝结量和液滴尺寸同时减小。节流过程中各组分的凝结性质存在较大差异。分子量较小的轻烃类组分,节流孔出口凝结量大,且凝结量和液滴尺寸受背压比和总温的影响大。     

An intelligent approach for calculating natural gas compressibility factor and its application in ultrasonic flow meters

The current study presents an intelligent method for calculating natural gas compressibility factor. The method requires three easily measurable properties including pressure, temperature, and speed of sound as inputs. As sound speed could be measured with ultrasonic flow meters, temperature, and pressure with appropriate sensors, the real-time natural gas compressibility factor could be calculated easily. The presented method eliminates the high cost of determining compressibility based on measuring natural gas composition. Artificial Neural Network is employed to develop the method. The artificial neural network is trained in a way to accept pressure, temperature, and speed of sound as inputs. To train an artificial neural network, the 30,000 random datasets of natural gas compositions were utilized. To check the validity and accuracy of the developed artificial neural network, four different natural gas compositions are selected and the compressibility factor are compared with the GERG-2008 equation of state (as standard and accurate method for calculating natural gas properties) results. The results reported the average absolute percent deviation is less than 0.7% for the compressibility factor calculation by utilizing the proposed method.     

On field characterisation of static domestic gas flowmeters

Different solutions to the metering of natural gas consumption can be adopted according to whether the distribution is domestic or industrial. In the domestic field, almost all the flow meters used by natural gas distribution companies are conventional diaphragm meters, whereas greater flow rates justify metrologically better performing measurement systems. The requirement for new safety and remote-reading related functions and the availability of new technologies is now encouraging the use of static innovative flow meters. In the present study, after a short analysis of metering principles and of static ultrasonic flow meter characteristics, the authors report the results of the field tests carried out on two different types of static ultrasonic flow meter for 2 years.