Analysis of influencing factors and uncertainty assessment of high-pressure natural gas primary standard facility

Abstract

The mass-time high-pressure natural gas flow standard device is the highest level natural gas flow measurement standard in China. It is mainly used to reproduce the mass flow of high-pressure natural gas and transfer the value. Due to its important position in the value traceability transmission systems, it is of great significance to improve its uncertainty. This article first introduces the working principle and component equipment of mass-time high-pressure natural gas flow standard device, and the influencing factors and control measures of the recurring mass flow uncertainty are given. Then the calculation model and uncertainty evaluation model of the mass flow rate of the standard device and the discharge coefficient of the critical flow nozzle are given. Finally, based on the calculation model, two critical flow nozzles are calibrated and tested, and their repeatability and stability indicators are discussed and analyzed. After analysis, it can be concluded that the measurement performance of the mass-time high-pressure natural gas flow standard device is stable, which can make the uncertainty of the reproduced mass flow rate less than 0.05 % (k = 2), and the uncertainty of the calibrated discharge coefficient of critical flow nozzle is less than 0.1 %(k = 2).