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.

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.

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.

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.

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.