AN ULTRASONIC GAS FLOWMETER USING HIGH FREQUENCY TRANSDUCERS AND CORRELATION TECHNIQUE |
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| P. Brassier, B. Hosten, F. Vulovic |
- Abstract:
- The research activities carried out in the past years showed that in gas networks some constraints exist on the ultrasonic working frequency of flowmeters. The study of the transmission and the attenuation of the signal, and noise mechanisms gives us a defined suitable frequency range. Thereby, a working frequency of 500 kHz proves to be the most suitable to avoid noise effects. This frequency is above the noise level detected in gas pipelines. Moreover, the signal lost due to attenuation of ultrasound in gas is still negligible. In parallel, the use of this frequency allows the application of efficient numerical techniques of signal processing such as the correlation method. An initialisation process based on this method is developed for gas flowmeters. It provides low uncertainty on parameters involved in the flow measurement process.
A single path flowmeter equipped with this system has been tested on the Gaz de France test facilities. Its accuracy is better than 1.5% from 250 to 1000 m³ / h without initial adjustment. The auto-calibration process also forms part of the system, using a systematic comparison between ultrasonic measurement of sound velocity and a theoretical approach. The signal to noise ratio remains large enough to perform correctly the measurements even with a control valve installed close to the flowmeter. - Keywords:
- ultrasonic gas flowmeter, ultrasound attenuation, valve noise, cross correlation, self calibration
- Download:
- IMEKO-TC9-2000-017.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC9
- Event name:
- FLOMEKO 2000
- Title:
- 10th Conference on Flow Measurement
- Place:
- Salvador, Bahia, BRAZIL
- Time:
- 04 June 2000 - 08 June 2000