Research and application of ultrasonic gas flow meter performance on-line audit

Ultrasonic flow meter has become the mainstream measuring instrument in the natural gas trade because of its advantages of large measuring range, small pressure loss and high measurement accuracy.In the measurement of natural gas with high pressure and large flow, the advantage of ultrasonic flow meter is particularly obvious.Ultrasonic flow meter based on transit-time method can measure the speed of sound and the flow velocity of fluid at the same time.With the continuous improvement of on-site monitoring and diagnosis technology of ultrasonic flow meter, the on-line audit of flow meter based on speed of sound checking has attracted extensive attention.According to AGA No.10 report, the online audit based on speed of sound checking was carried out with a 4-path ultrasonic flow meter used in a natural gas station was studied.The studies showed that within 2 years, the signal quality indicators of the ultrasonic flowmeter were basically the same, the variation of flow velocity deviation was within ± 0.5%, and the variation of the speed of sound deviation of acoustic path was within ± 0.03%.With the comparison of the real flow calibration, it could be concluded that the metering performance of the flowmeter was stable and reliable, but the installation conditions should be checked to see if they meet the requirements.The results showed that the method of on-line audit can effectively monitor the performance of ultrasonic flowmeter and could be a powerful supplement to the real flow calibration.