Uncertainty study of fiscal orifice meter used in a gas Algerian field

Uncertainty variation of a fiscal orifice measurement system used in an Algerian natural gas exportation station is studied using data from a natural gas production field known as Gas Tin Fouye Tabankort (GTFT) located in the south-east of Algeria. The expected results are uncertainty calculus over a range of temperature and pressure variation and to the customs authorities’ allocation.In fact, each quantity of measured fluid flow has certain uncertainty and then the fiscal measurement station is very important for gas exportation, which means the income. Therefore, the pursuit of flow metering device uncertainty and its influence on the measured quantities in the transmission networks is very important.For that, the uncertainty caused by flowmeter in the measurement station causing economical revenue fluctuations is studied. The work was done to justify why there is a production decrease of hydrocarbons without identifying reasons during summer. The difference between the mass flow rate quantity produced and the transmitted value was important that is why our work is done to clarify exactly from where the problem can come.The measurements setting with two operating conditions (gas temperature and pressure) show that the uncertainty is dominated by seasonal temperatures and pressures variations which induce fluctuation in gas and pipe temperatures and influence the metrological performance of the transmitters. Indeed, the metrological measurement chain performance is affected also by these two operating conditions.The present work is done according to the ONML (National Legal Metrological Office) instructions regarding differences between the measured and the seller values represented by the mass flow rate.In natural gas transmission network, the important problem in the management and control of the network is represented by the unaccounted for gas, a quantity of measuring error which is to be considered in the equation of network balancing. One of the unaccounted for gas sources are the environmental conditions and systematic measurement errors.In this work, the calculation of the combined uncertainty of the mass flow rate measured by an Orifice fiscal gas metering plant is done. From the results founded, the authors confirm that the uncertainty in the measurement system causing by the climatic conditions generates unaccounted for gas.     

Fiscal liquid and gaseous hydrocarbons flow and volume measurement: Improved reliability and performance paradigms by harnessing for fourth industrial revolution

The oil and gas markets are of fundamental importance to the world's scenario dealing with high value products. Several rules and regulations define the various operating procedures due to environmental, social, political, and financial impacts. Liquid and gaseous hydrocarbon measurement stations are inside this context, either in the transfer of ownership of the product (custody transfer) or for values calculation for tax purposes (fiscal measurement). This is a conservative application in the industry but one that cannot fail to introduce the new features provided by the advances of the fourth industrial revolution. Thus, this article, based on a broad bibliographic research based on a qualitative analysis, addresses the concepts of some technologies already available in the automation market and how they can be applied to these stations to provide a greater reliability through risk reduction.     

Gas mass-flow meters: Measurement and uncertainties

The application of gas mass-flow meters (GMFM) sensors needs the knowledge of its measurement model and measurement uncertainties. It was already known that the GMFM output model depends on gas mass-flow and gas composition. In this work, different throughput GMFM sensors were used for different gas flow rates and gas composition in order to verify and to improve the GMFM measurement model.A direct calibration procedure and a dynamic volumetric method were applied both to get the measurement model and to evaluate the performance of gas sensors and GMFM sensors against certified reference materials and suitable standards. Additionally, the obtained data were used both to calculate the uncertainties of gas mass-flow measurement and to improve the GMFM gas response factors.The calculated uncertainties of the GMFM direct measurement was approximately 2% of the measured value. The uncertainty of the dynamic volumetric method developed in this work was found as approximately 5% of the measured value and that was mainly influenced by the uncertainties of the standards used.     

Traceability to SI units for vacuum measurement in industrial applications

In the context of international standards like the ISO 9000 series or ISO 17025 the traceability of measurement instruments of physical units in industrial processes gained more importance in the last two decades, so to say also for vacuum measurement. Traceable calibrations of vacuum gauges ensure agreement with the SI units. For this purpose vacuum primary standards are needed. The international system of metrology ensures that the vacuum primary standards registered in the system are equivalent and fulfill their specifications. Secondary and reference standards are used to disseminate the pressure scale in vacuum to calibration laboratories, to the manufacturers of gauges, and finally to industrial processes or to research facilities. Suitable vacuum gauges for this purpose including their expected measurement uncertainties will be described. Notes for the measurement uncertainties at the place of the end user will be given.     

Impact of uncertainties in accelerometer modeling on the maximum values of absolute dynamic error

The paper considers the impact of uncertainties associated with estimated parameters of the accelerometer model on the maximum values of absolute dynamic error. Assessment of such impact constitutes a novelty in determination of the maximum values of absolute dynamic error.The parameter estimation method of the accelerometer mathematical model in the frequency domain and the procedure for calculation of the associated uncertainties under the current regulations, are discussed in detail in the second section of this paper.The procedures for determining the maximum values of absolute dynamic error generated at the output of an accelerometer, when the input signals are constrained in magnitude and both in magnitude and rate of change, are discussed in the third section. This dynamic error has been determined in relation to the standard represented by the 15-th order Butterworth filter. The possibilities of application of both the continuous and the discrete procedures of error calculation have also been presented. For the execution of numerical integration, the Romberg method has been applied.Based on theoretical consideration, the results of both the parameter estimation of the Endevco87 accelerometer and calculation of the corresponding uncertainties are presented in the fourth section.The fifth section is devoted to the presentation of the most important assumptions, which allow the determination of the maximum values of absolute dynamic error.An assessment of the impact of the uncertainties associated with the estimated parameters on the value of absolute error is discussed in the last section of this paper.The numerical calculations were executed in the MathCad14 program.     

色谱分析仪在天然气计量中的应用

天然气各组分含量是天然气计量的基础参数,天然气气质的准确分析对天然气计量至关重要。气相色谱法是测量天然气组成最常用的方法,气相色谱法具有选择性高、分离效率高、灵敏度高、分析速度快等特点。本文介绍了Pro GC-2000天然气色谱仪在绍兴天然气门站输气管道处的成功应用,通过在线色谱仪实时取样分析,得到天然气组成、密度、发热量、沃泊指数、压缩因子等物性参数,并将结果及时输入流量计算机中,实现对天然气流量和能量的及时修正,确保天然气计量准确可靠。本文阐述了色谱分析原理、结果分析方法、天然气计量系统组成和工作原理等。     

RPG—HATPRO地基多通道微波辐射计的使用与维护

RPG-HATPRO地基多通道微波辐射计是一款大气垂直遥测的温度和湿度廓线仪,通过神经网络算法利用大气衰减特征分析反演边界层和对流层大气的温度、湿度、水汽密度及液态水廓线,为大气环境综合观测及空气质量预报预警提供综合分析手段。根据实际使用经验,对RPG-HATPRO地基多通道微波辐射计的仪器结构、测量原理、工作流程和运行维护等方面进行了介绍和总结。     

Simple sensitive capacitance manometer for corrosive gas laser systems

The design and performance of a capacitance manometer for use in corrosive gas laser environments is presented. This simple and inexpensive isolating device can be quickly fabricated in any machine shop, and permits the utilization of ordinary non-passivated pressure measurement apparatus or gauges in any gas system, irrespective of the corrosiveness.     

Pressure transmitter accuracy

This paper discusses the key causes of calibration drift in pressure transmitters and procedures for calibrating pressure transmitters to ensure their accuracy. Calibrating pressure transmitters involves adjusting the potentiometers in the sensor that controls the zero (lowest pressure at which a transmitter is calibrated) and span (the range of pressure the transmitter is to indicate) of the transmitter. The initial or bench calibration of pressure transmitters involves using a constant pressure source such as a deadweight tester. Once the transmitters are installed, temperature, pressure, humidity, vibration, maintenance activities, and normal aging can degrade their accuracy. Transmitter accuracy can also be degraded by transmitter sensing lines, when the water in a sensing line reference leg boils off, when non-condensable gases in the reference leg dissolve, and when voids, blockages, freezing, or leakage occur in sensing lines. On-line calibration techniques enable plants to avoid these accuracy problems by monitoring the output of an individual transmitter.     

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.     

螺纹量规的数字化检测方法

螺纹量规是判定螺纹紧固件合格与否的重要量具,其几何参数的精确测量具有重要意义。利用螺纹综合测量仪完成了螺纹量规的数字化测量试验,分析得出该方法的测量结果准确,精度可靠。同时对螺纹综合测量仪测量中径的不确定度进行了评定,为螺纹量规的测量质量提供了参考依据。     

Impact analysis of the oxidant in the process of underground coal gasification

Technology of Underground Coal Gasification (UCG) is still under developing and providing alternative for conventional underground coal mining. Underground coal gasification is a process with may be environmentally and economically attractive for widespread use in the future. The quality of the produced gas from UCG can vary substantially depending on the injected oxidant used, operating pressure, oxidizer flow rate, type of coal, hydrological conditions of the coal seam, coal type and the mass and energy balance of the underground reactor. Paper analyzes the impact of the oxidant on calorific value of the syngas in a laboratory and operating conditions. Also is analyzed the effect of temperature in the oxidation zone of gasifier on gas composition and calorific value. Effect of oxidant on the gasification process has been verified on experimental gasifier equipment. The paper describes an experimental gasifier and devices that were used for measurement and control.     

A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers

The present work introduces a numerical model for squeeze film dampers (SFDs) operating simultaneously with vapor cavitation and air ingestion. The pressure is given by the Reynolds equation. The vapor cavitation model used in this work is based on Rayleigh-Plesset equation and was previously presented. Air ingestion occurring in open-end SFDs is dealt with by using a volume of fluid computational fluid dynamics (CFD) method not previously employed in lubrication problems. The original volume of fluid (VOF) method proposed by Hirt and Nichols was adapted to capture and track the free boundary between air and liquid in a thin-film lubricant. Numerical results are compared with experimental data of Adiletta and Pietra showing the simultaneous influence of vapor cavitation and air ingestion in an open-end SFD. These two phenomena have typical pressure values and appear at different locations and with a different extent. The vapor threshold is located on the low-pressure zone and is the lowest pressure value in the SFD, usually close to absolute zero. The air ingestion is characterized by a zone of almost constant pressure, usually close to atmospheric pressure (or, more generally, equal to the outer, exit pressure) and located between the minimum and the maximum pressures in the SFD. The numerical model proposed in this article deals simultaneously with these two effects. A simplified version of the air ingestion model for standard SFD applications is also introduced.     

Interferometric,absolute sensor of angular micro-displacement

A design of a new, absolute sensor for measurement of an angular micro-displacement is presented. In this sensor deflections of incident laser beam generate changes of the constant of the interference fringes that are created by the double arm special interferometer. Fringe constant is determined using a CCD camera and proposed analysis algorithms. Sensor's operating principle and metrological properties are presented. Sensor was tested using reference interferometer. Obtained measurement uncertainty is equal to ±10 μrad in the multi-milliradian range. The concept of a two-sensor system for increasing twice the measuring range is presented.     

Real-time monitoring of railroad track tension using a fiber Bragg grating-based strain sensor

Railway and train security are very important in preventing service disruption and ensuring quality and safe journeys. Conventional gauges are used in laboratory environments for the strain measurement of rails used in railways. However, the use of these electrical sensors is not practical in long-distance railways. Instead, access to long distances is possible with fiber optic sensors. In this study, the strain of 49E1 type rail with R260 hardness and quality was calculated theoretically. These results were compared with an experimentally established fiber Bragg grating system. Moreover, a user-friendly interface was prepared for real-time monitoring of the system. Upon examining the results, the maximum deviation at a rate of 2.5% occurred in the strain measurement in the rail in response to force changes between 0 and 200 kN. A value of approximately 1.38?pm/µε was calculated between the wavelength/strain changes.     

伺服阀滑阀副叠合量快速气动测量及数据分析方法

为了提高电液伺服阀滑阀副的配磨效率,需要缩短叠合量测量时间.采用气动流量法,设计了一套测量气路和对应的测量流程,通过减少阀芯驱动行程实现叠合量快速气动测量.针对气动测量过程中出现的测量压力变化和相邻阀口气体泄漏问题,采用流量转换和曲线相似度分析的方法,获得恒定压力下的流量-位移曲线及相应的叠合量计算方法.通过实验和工程...     

Soft-sensors: Model-based estimation of inflow in horizontal wells using the extended Kalman filter

The growing demand for hydrocarbon production has resulted in improved oilfield management using various control and optimization strategies. These strategies increasingly require downhole equipment to obtain real-time oil and gas production rates with sufficient spatial and temporal resolution. In particular, downhole multiphase metering can improve the production of horizontal wells by allocating the zones of oil, gas and water inflow. However, the existing downhole multiphase meters are expensive, inaccurate or accurate only within a limited operating range and therefore such monitoring is unrealistic.To overcome these problems one can use the so-called multiphase soft-sensors, i.e. estimating flow rates from conventional sensors (e.g. pressure gauges) in combination with a dynamic multiphase flow model. This methodology uses inverse modeling concepts to estimate flow rates that are not measured directly. Based on the analysis of the transient pressure response due to a rapid inflow, a real-time estimator is proposed, which uses a dynamic model of the multiphase wellbore flow and information from conventional pressure sensors. The feasibility of the proposed concept is assessed via simulation-based case studies both for noisy synthetic measurements and for artificial data generated by the OLGA simulator.     

A CFD study of wet gas metering over-reading model under high pressure

The venturi flow meter is increasingly being preferred in multiphase flow measurement because of its shorter upstream and downstream straight sections, less influenced by the flow pattern and relatively small pressure loss. However, when the venturi is used for wet gas measurement, the over-reading phenomenon occurs due to the presence of a small amount of liquid. Many scholars have established over-reading models to correct the measured values of wet gas. Regrettably, the applicability of these over-reading models under actual high pressure operating conditions has not been verified. Therefore, this review focuses on numerical simulation of the flow of wet gas in the venturi tube under high pressure conditions (11MPa/13MPa/15 MPa). The discrete phase model (DPM) and the standard k-ε model was employed in this review. The simulations results reveals the flow characteristics of wet gas in venturi tube, which includes the flow field distributions, droplet concentration distributions and wall pressure profile distributions, and indicates that the over-reading values increases with the increase of Lockhart-Martinelli parameters and gas volume flow rate, but decreases with the increase of pressure. Moreover, the ISO model has the best performance under high pressure conditions.     

Analysis of pressure distribution for the various gas flow vacuum system in the range from 1 Pa to 133 Pa

The measurement and control of gas flow are critical in many manufacturing processes. Semiconductor manufacturers, in particular, require a number of different process gases for etching, deposition, oxidation, doping and inerting applications. In many of these, as well as other industrial and research processes including measurement of partial pressures with residual gas analyzers (RGAs), calibration of vacuum gauges, and conductance of a conductance-reducer , accurate measurement and stability of the gas pressure within the reaction vacuum chamber is essential. In the present work, pressure distribution in the chamber of a newly developed flow control system was investigated for three gases (Ar, N₂, and He) range from 1 Pa to 133 Pa. For all the gases, the relative deviations in pressure distribution near the gas inlet and outlet were in the range of −1.3% and 1.2% respectively.     

Air gauges as a part of the dimensional inspection systems

Air gauges for dimensional measurement are known for decades. They have been applied in many technological processes, especially in the systems of in-process control. The air gauges are connected with pneumatic measuring devices able to generate control signals. Nowadays, however, it is not enough to just indicate dimensional bounds of tolerance. The Quality Management Systems require recorded and processed data achieved during the measurement. Investigations led to the development of air gauges integrated with piezoresistive pressure transducers. In those systems the results of measurement are achieved in digital form, they are processed and recorded. Additionally, dynamical properties of integrated air gauges appear much better. Multipoint linearization of the air gauge appears to be advantageous, though some companies offer the adjustment using one setting master only.