## IMEKO Event Proceedings Search

Page 18 of 912 Results 171 - 180 of 9113

**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.

**Exploration and Application of Opt-Sonic Correlation Measurement Technology to Realize Energy Determination for Naturl gas**

The traditional volume measurement method of natural gas is greatly affected by changes in temperament conditions, thus affecting the normal trade measurement, and can no longer adapt to the current domestic gas transmission status of multiple gas sources.In this context, this study proposes a Sound and light association method measurement technology not limited by the natural gas component to directly determine the natural gas heat generation, thus realizing energy measurement. Combined to the actual operation of natural gas station, the data of multiple multi- component gas standard substances and comparison with the results of chromatographic analyzer are analyzed, The accuracy of the sound and Sound and light association method for heat generation measurement and energy measurement is verified. Finally, the stability of heat measurement was verified by a 5-month interval test. The experimental results show that this technique is extremely useful in the field of energy measurement.

**Design of gas flow standard device for online or remote calibration of gas flow**

Online/remote calibration is the transformation and expansion of traditional measurement. Its development will play a certain role in strengthening measurement management, improving the overall strength and level of measurement, and promoting trade and economic development. In this paper, a set of on-line/remote detection standard devices with a flow range of (0.4 ~ 400) m³/h, expanded uncertainty: U ≤ 0.33 %, k = 2 was designed and developed. Rely on the Internet + calibration mode, use the wireless Internet to send signals from the laboratory to the standard testing module, establish a remote service to send remote control commands, monitor the physical and electrical connections, and control the standard testing module. The program controls the calibration process automatically complete online /remote calibration.

**Standard Device of Natural Gas Real-flow Detection**

In my country's primary energy consumption structure, the proportion of natural gas is increasing. Accurate and reasonable measurement of natural gas is one of the important links in natural gas utilization, which has huge social and economic benefits. The Chongqing branch of the National Petroleum and Natural Gas Large-flow Detection Station has established a set of standard equipment for real-flow detection of natural gas. The device uses 10 critical flow venturi nozzles with different throat diameters in parallel, and uses the 1.6 MPa natural gas stored in the upstream 5500 m³ spherical tank as the verification gas. One of the biggest advantages of this device is that the pressure of the upstream natural gas source is relatively stable and the gas quality is clean. There is no need to add a voltage stabilizer and a purification device, and it can realize the verification of gas flow meters such as ultrasonic, turbine, and waist wheel. The working pressure of the device is (0.1 ~ 1.2) MPa, and the standard flow qN is (14 ~ 19000) m³/h. The measurement uncertainty of the device is evaluated, and the uncertainty of the device is Ur = 0.28 %, k = 2. A SICK DN200 gas ultrasonic flowmeter was calibrated using this testing standard device and the uncertainty of the measurement results was analyzed, and Ur = 0.32 %, k = 2.

**Simulation Study on Measurement Method of Flow Fluctuation Signal Based on Chaotic Oscillator**

Based on the initial sensitivity of chaotic oscillator which is sensitive to regular signal and immune to noise simultaneously, the chaotic signal detection method can detect the signal submerged in the noise stronger than the measured signal, and relevant research has been applied to measure weak signals submerged by large noise. In this paper, chaotic oscillator is applied in flow fluctuation signal detection of a flow standard device, and a new detection model is proposed to detect the fluctuation signal using the maximum Lyapunov exponent to obtain the threshold value and monitor motions transition of detection system. The Holmes Duffing oscillator is chosen to work as the detection system. Fourth-order Runge-Kutta algorithm is used to solve the function of Holmes Duffing oscillator and to calculate maximum Lyapunov exponent. Simulation experiment on different frequencies fluctuation signal and under different levels of noises is conducted. Simulation results show that detection model can effectively detect the flow fluctuation signal output by flowmeter, and it is immune to the noises.

Page 18 of 912 Results 171 - 180 of 9113