对“用气体超声流量计测量天然气流量”国家标准的修改建议

气体超声流量计具有测量准确度高、适应性强和自诊断能力强等优点而被广泛用于天然气生产、输送及销售计量中,中国与俄罗斯天然气贸易交接计量就使用了超声流量计。为了提高天然气贸易交接计量的准确度、维护贸易双方合法的经济利益,分析比较了气体超声流量计国际标准ISO 17089-1—2010、俄罗斯标准ГОСТ8.611—2013和中国国家标准GB/T 18604—2014等3个标准的适用范围、测量气质条件、超声流量计技术指标、安装要求和现场测量性能保障措施等方面的异同点,并进行了2台超声流量计串联安装计量试验,开展了试验数据的重复性、安装位置对计量性能的影响和流量差值控制限分析,在此基础上提出了对GB/T 18604—2014的修订建议。研究结果表明:(1)中国标准同国际标准的主要技术内容是基本一致的,但前者在超声流量计使用过程质量控制方面还有待加强;(2)建议GB/T 18604—2014增加ISO 17089-1—2010中超声流量计两次校准误差限、测量误差处理方法以及串联安装超声流量计比对方法等方面的内容。

Recommended revision of the Measurement of Natural Gas Flow by Ultrasonic Gas Flow Meters (GB/T 18604-2014)

Ultrasonic gas flow meters are widely applied to the metering of natural gas in production, transmission and marketing sectors owing to their advantages of high accuracy, high adaptability and high self-diagnostic capacity. They are used for the custody transfer metering during the China–Russia natural gas trade. To improve the custody transfer metering accuracy in natural gas trade and protect the legal economic benefits of both trading parties, three standards on ultrasonic gas flow meters (i.e., the international standard ISO 17089-1-2010, Russia's standard ГОСТ 8.611-2013 and China's standard GB/T 18604-2014) were comparatively analyzed from the aspects of application, gas quality condition, technical indicators, installation requirements and field measurement securities. Then, a metering test was conducted on two ultrasonic gas flow meters that were installed in series, and the reproducibility of test data, the effect of installation sites on metering performance and the control limit of flow rate difference were analyzed. Accordingly, the recommendations were proposed on the revision of GB/T 18604-2014. It is indicated that GB/T 18604-2014 is basically consistent with the international standard in terms of main technical contents, but the former shall be strengthened in terms of quality control during the operation of ultrasonic gas flow meters. It is recommended to add GB/T 18604-2014 with an error limit of two calibrations of ultrasonic gas flow meters, the measurement error treatment method and the comparison method of ultrasonic gas flow meters installed in series that are included in ISO 17089-1-2010.