## IMEKO Event Proceedings Search

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**Research on the traceability verification technology of quantity value of standard water flow facility based on mobile comparison method**

Standard water flow facility (hereinafter referred to as the standard facility) is used for the calibration of cold and hot water flow meters. According to JJF1001-2011 “General Metrology Terms and Definitions” the standard facility needs to be verified that the quantity value stays in the original status in order to ensure the quantity value can meet the requirements during operation. And the verification will help to identify the inaccuracy, to shorten the traceability time after that, and to minimize the test costs and quality risk as far as possible.This project studies a technical method for verifying the traceability of quantity value of standard water flow facility based on mobile comparison method. According to JJG 164-2000 "Standard facilities for Liquid Flowrate”, the total uncertainty of the standard facility for cold and hot water flowrate is determined by calibrating the timer, commutator, scale, calibrated measuring volumetric tank, etc. and the traceability of the quantity value of the facility is completed. The core of this study is how to verify the overall impact of the facility in use due to piping system, hydraulic stability, gas tightness, flow fluctuations, etc. on its reproducible quantity values.

**Numerical simulation-based experimental study on theeffect of different disturbed flow components on ultrasonic flowmeter metering performance**

Ultrasonic flowmeter is a velocity flowmeter, and its measurement accuracy is greatly affected by the flowfield in the pipeline. In the actual use process, due to the installation conditions are not ideal, the formation ofvortex flow, pulsating flow, asymmetric flow and other non-ideal flow field in the pipe, which in turn affects the accuracy of ultrasonic flowmeter. This study is based on CFD numerical simulation technology, 90° elbow, reducer, upstream and downstream flange diameter difference of one level and other typical disturbanceelements on the impact of the flow field in the pipe, simulate the flow field of the gas in the closed pipe after the disturbance elements, and calculate the resulting error, found that the impact of each disturbance element on the ultrasonic flowmeter measurement error increases with the increase in operating flow. For 90° elbow, the upstream and downstream flange diameter differ by one level, we use these two installation conditions to carry out real flow test, through the test data and simulation results for comparison and analysis, the results are consistent. At the same time, the use of experimental data on the simulation model correction, can guide the construction and transformation of ultrasonic flowmeter metering process, improve the accuracy of the measurement results, and effectively maintain the fairness of the trade handover.

**Discussion on measurement and evaluation method ofnatural gas flow computer**

As an important measuring instrument and basis for the handover of natural gas measurement trade, it is necessary to formulate requirements and test standards for evaluating its structure, performance, safety and consistency. The computer evaluation and detection software of natural gas flow is developed, which realizes the functions of data acquisition and evaluation, flow calculation and verification, physical parameter evaluation and environmental impact factor evaluation. The design, software and hardware configuration of natural gas flow computer evaluation and detection system are completed, and the flow is established.Thecomputer evaluation and detection standard device forms a natural gas flow computer evaluation anddetection system, realizes the evaluation of the accuracy of the flow computer and its supporting sensors, and carries out laboratory and field application test experiments on the evaluation and detection system.

**Study on the effect of pressure on gas ultrasonic flowmeter**

With the ultrasonic flowmeter (Ultrasonic Flowmeter) in the natural gas metering is widely used, ultrasonic flowmeter accuracy is increasingly concerned. however, by the limitations of the calibration operation conditions, there aredifferences between the calibration operation conditions and actual operation conditions , and operation conditions on theimpact of ultrasonic flowmeter metering lack of systematic research, Wuhan branch station established a mobile natural gas metering standard device can be carried out in different pressure conditions of the gas transmission station calibration services.In this paper, we study the calibration tests carried out by the mobile natural gas metering standard device at different pressures, and through analyzing and integrating data, we derive the metering deviation caused by ultrasonic flowmeter under different working conditions, establish the mathematical model of Reynolds number error correction toguide the use of ultrasonic flowmeter, and eliminate the deviation introduced by the different operation conditions of calibration and use, improve the accuracy of trade measurement, while the research results can be the technical support for the revision of relevant standards and norms.

**Research on the calibration of Sonic Nozzles by HPPP**

The mathematical model and the measurement uncertainty of the outflow coefficient for calibrating the sonicnozzle with the High Pressure Piston Prover (HPPP) primary standard device were studied. The design and modification of the existing HPPP primary flow standard device were carried out. , replace the upstream transmission turbine flowmeter with an ultrasonic flowmeter, and replace the downstream transmission turbineflowmeter with a set of inspected sonic nozzle pipe sections, optimize the uncertainty of the measurement results, and realize the function of calibrating the sonic nozzle with the HPPP primary standard device.

**A New Type of Flow Measurement Device**

Flow measurement plays an important role in industrial production, process control and energy utilization. The steam flow is affected by the state of steam properties and the design of the steam flowmeter during the measurement process, resulting in low measurement accuracy. Based on the combined measurement method of differential pressure flowmeter and vortex flowmeter, an integrated flow measurement device that integrates averaging-velocity tube and piezoelectric vortex flowmeter is proposed in this paper. It combines the structural features and advantages of the two flowmeters scientifically. In this paper, the differential pressure transmitter is used to detect the pressure difference on both sides of the cylinder. Due to fluid vibration and piezoelectric effect, the probe in the device generates regular vibration. And combined with Digital Signal Processing (DSP) technology and automatic frequency band adjustment method, the flexibility and stability of frequency signal processing are improved. The measurement performance of the device was evaluated in this paper. The experimental results show that the absolute value of the relative error of the device is within 1.00 % and 1.50 % under the conditions of single-phase water and single-phase gas, respectively. The device can achieve dual-signal measurement, and it has the advantages of wide applicability, good stability and strong anti-interference, which will provide a new design idea for the measurement of saturated wet steam.

**void fraction measurement using the coaxial line phase technique in the vertical gas-liquid slug flow**

Based on the electromagnetic wave propagation principle, a prediction model based on the phase difference of coaxial lines to measure the void fraction of the slug flow is proposed, and experiments on vertical tube slug flow are conducted under 70 working conditions. A new mixing dielectric constant measurement model is established by adding a phase mixer device to the sensor to stir the slug flow into a popular and stable homogeneous flow. The homogeneous flow under the same experimental conditions is used as the reference true value of the slug flow measurement section void fraction model, and the prediction model is validated and optimized. The results show that the MAPE value of the optimized measurement model is reduced from 2.96 % to 1.02 % without the addition of a phase mixer, and the prediction of the void fraction of the slug flow ia improved compared with the previous one.

**Comparison of different slug frequency calculation methods for the validation of two-phase flow simulations**

Slug flow is a common flow pattern, which is often accompanied by undesired effects, like pressure loss or vibrations, leading to large errors in multiphase flow metering. Because these undesired effects strongly correlate with the frequency of slug occurrence, this parameter is of special interest. In this paper, different slug frequency calculation methods are applied to data from multiphase flow simulations and corresponding high-speed video observations for six test cases within the plug / slug flow regime. Commonly used methods, like power spectral density (PSD) or calculating the mean slug frequency by applying a fixed threshold, are compared with new evaluation methods. Since every approach has its pros and cons, it is recommended to apply different methods to each data set. The deviations in the resulting slug frequencies indicate how much one can trust the results. If large variations are observed, one should apply an advanced technique for the calculation of the liquid level / hold-up, which takes aeration into account.

**Thermal Mass Flow Controller Induced Temperature Fluctuations in a Gas Flow Calibration Line at NMISA**

The National Metrology Institute of South Africa’s (NMISA) gas flow laboratory uses TMFCs to control gas flow rate during calibration of gas flow meters. The TMFC is connected upstream of the unit under test (UUT) during calibration. The laboratory performs gas flow calibrations in the range 5 mL/min – 50 L/min using nitrogen as flow medium. The gas temperature at the UUT’s location downstream of an TMFC has been found to fluctuate proportionally to the change in the flow rate at flow rates above 250 mL/min and below 22.5 L/min. This temperature fluctuation has a significant effect on measurements by volumetric gas flow meters not installed with temperature and pressure sensors. The temperature fluctuations are attributed to heat generated by the MFC electronics and transferred via thermal convection currents, and the heat absorbed by the gas flowing through the capillary sensor tube. This paper discusses gas temperature fluctuations observed at the NMISA flow laboratory as gas flow rate is changed using a TMFC. It also discusses a calibration setup used to measure temperature and pressure at the UUT’s location for volumetric gas flow meters without temperature and pressure sensors. These temperature and pressure measurements allow the metrologist to convert volumetric flow rate to mass (standardised) flow rate at a specific temperature (Ts) for instruments such as bubble flow meters. The temperature Ts is chosen such that it matches field temperature as close as possible.

**Influence of Different Treatment Methods of Neopentane in Natural Gas Components on Measurement Accuracy**

The main sources of domestic pipeline natural gas are central Asia, the Tarim Basin, the Sichuan Basin, and the Zhonghai Oil and Gas Field, etc. Due to the large geographical differences in gas sources, the components of natural gas are quite different. Therefore, accurate analysis of natural gas composition and calculation of the corresponding compression factor is an important part of the natural gas custody transfer process. There is a certain proportion of neopentane in current domestic natural gas, but there are no calculation parameters of neopentane in various corresponding calculation standards, including GB/T 17747/ISO 12213 and AGA 8 standards for compression factor calculation and GB/T 30491.1/ISO 20765-1 and AGA10 standards for sound velocity calculation. However, in theory, the treatment method of neopentane will directly affect the compression factor of natural gas, and then affect the measurement results. Therefore, how to deal with neopentane in natural gas and ensure the accuracy of natural gas measurement results is a problem worthy of study.

Generally, there are three ways to deal with neopentane in natural gas: (1) adding neopentane content to isopentane with similar properties; (2) adding neopentane content to n-pentane; (3) to normalize the neopentane content. In order to confirm the influence of the three different processing methods on the measurement accuracy of the flowmeter, the theoretical calculation and actual test verification are used for comparative analysis. The conclusions are as follows: The three treatment methods of neopentane have a certain influence on the calculation results of natural gas compression factor, but the overall influence is small. For the common components of domestic pipeline natural gas, the standard meter method and critical flow Venturi nozzle method standard devices are used to verify the tested flowmeter respectively. The maximum deviations of natural gas compression factor and indication error are 0.00001 and 0.00003 %, 0.00001 and 0.00301 %, respectively, namely, the different treatment methods of neopentane have little impact on the measurement results. Therefore, as an inherent component of natural gas, neopentane can be treated in the above three ways in trade measurement.

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