Dannal Cheng, Feng Gao, Junfeng Mao, Shi Wu, Xinli Dong, Han Zhang, Qian Zhang
Probe into methods about the comparison of gas flowmeters

At present, the way to check the flowmeter accuracy is disassemble them and send to flow lab and verify it. But customer don’t like it, because it will affect or stop their production. What the customer really need is toknow the meter accuracy but non-disassemble flowmeters. It is not an easy way, this paper describes a feasible solution about inline comparison of gas flowmeter by inline drilling, inline installation, power supplyand data recording & analysis. In the end, cited a field case about comparison of gas flowmeter.

Han Xu, Zheng Hongwei, Song Chaofan, Zhou Lei, Wu Yan, Hong Bingyuan, Wen Kai
Fully automated controller for the real-flow calibration of natural gas flowmeters based

With the rapid development of the natural gas industry, the natural gas measurement handover volume is increasing year by year, and the calibration of natural gas flowmeter is becoming more and more important. This paper defines and demonstrates the framework of a fully automated controller for natural gas flowmeter calibration stations, from conceptualization to field test. When the calibrated flowmeter is installed on bench, the controller will identify the corresponding process by success tree algorithm. It checks whether the current process is appropriate, and automatically switch the best process according to the diameter of the calibrated meter. In the regulation stage of different calibrated flow rates, the controller performs predictive control on different flow rates according to the actual hydraulic condition by the calculation of hybrid driven model based on neural network model and mechanism model. This process gives the initial position of regulating valves with fast and efficient movement. Under a mild PID control law, the actual flow will go to the setting flow rates neither overshoot nor fall back. Finally, the control scheme is demonstrated in three original case studies, one in the simulation environment built by hydraulic simulation software, and the other two in real systems with different complexity. The algorithm is verified by simulation software and the control scheme is implemented in the actual environment. The results show that the intelligent calibration process based on model predictive control can increase the calibration efficiency. The integrated system based on hybrid driven can promote the intelligent development of natural gas calibration stations.

L. Cordova, I. Marfenko, A. Pfau, L. Shen
Considering Covariance in Reference Flowmeter-based Calibration Facilities

Given their simplicity, flow calibration facilities using flowmeters as reference standards are very common. The present paper introduces a method to estimate calibration facility uncertainty considering empirically determined correlation effects under working conditions. This improvement strongly increases the confidence in flowmeter-based calibration facilities of the particular type used, making third-party recognition of calibration services more reliable and transparent. A special type of calibration facility having multiple reference flowmeters installed both in-series and in-parallel, and fully automated scale calibration systems using weights was used. No human intervention is required for the calibration of the gravimetric system. When no covariance is considered, the expanded uncertainty of the facility can be expressed by the single flowmeter uncertainty reduced by the factor 1/m², m being the number of flowmeters used in parallel or in series; for two devices in n lines, by the factor 1/(2n)². This approach has its limitations and does not address possible unknown systematic effects during the calibration of each reference flowmeter. A more conservative approach assumes full correlation between the flowmeters used. The tested facility was designed to make covariance between two simultaneously calibrated reference devices measurable. By knowing the covariance, better understanding is given to the real performance of the reference flowmeters under working conditions and no full correlation needs to be assumed. In this paper we present firstly theoretical considerations and discuss the assumptions for modelling this particular type of facility. Secondly historical data is presented and analyzed, and finally, the facility performance of 0.03 % up to 100 kg/s is validated through flow comparisons using a highly accurate reference flowmeter.

Chaojian Tao, Jiaodan Chen, Liqiong Huang, Shuqiang Chen, Shuxi Lin, Qiang Lin, Zeng Hong
Research on Temperature Control Technology of high- Pressure Loop Gas Flow Standard Facility

The high-pressure loop gas flow standard facility (hereinafter referred to as the facility) is a working measurement standard [1] for gas flowmeters to perform measurement performance tests under different pressures. It can study and improve the measurement performance of flowmeters under different pressures and different gas media, which is of great significance to the research of flow measurement technology. This paper studies the temperature control technology of the facility, the purpose is to make the temperature meet the working requirements of the facility and as close as possible to the existing international advanced level. Through theoretical analysis and experimental methods, combined with the author's company and the experience of external construction facilities, this paper designs an intelligent control system including its various subsystems, and realizes the design requirement that the temperature change of the facility's working gas is not greater than ± 0.1 °C/min. This paper shares the construction experience, and proposes a technical route for further improvement by using advanced control methods such as fuzzy control and neural network control to reach the existing international excellent level of ± 0.05 °C/min.

Liu Wei, Li Li, Chen Wei, Zhan Jiao, Liu Yahui
The flow performance testing device of the ambient air sampler

In this paper, the flow measurement performance of the ambient air sampler is studied, which is widely used in environmental monitoring, health care and mining enterprises. The paper develops the flow rate performance test device of ambient air sampler, which consists of the high-low temperature test device, the load performance test device, the flow standard device and the pressure measurement device. For various types of ambient air samplers and its calibrators, the device can carry out flow performance tests with the flow range of 10 mL/min ~ 265 L/min, with flow indication error no more than ±2%, the high-low temperature tests with the range of (-20 ~ 40)℃, and the load performance tests in the range (-50 ~ 0)kPa. The uneven capability of temperature adaption of different types of samplers or from various manufacture is found through experiments research, but the flow metering performance of samplers is significantly improved compensated by temperature in this paper. In the load test, the sampler load condition of different ranges or manufacturers are different, which meets the requirement of more than 50 % the air extraction capacity.