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  5. Uncertainty evaluation of gas flow rate measurements by ultrasonic transducer

Uncertainty evaluation of gas flow rate measurements by ultrasonic transducer

T. Vladimirova, M. Shalabanova
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Description: The required level of accuracy of gas flow measurements is defined commonly by the conditions peculiar to sphere of the results application. The technique, which is proposed in the article, enables the conduction of estimation of volumetric flow rate and volume of gas with inherent parameters converted to standard conditions, according to exact accuracy norms of measure-ments and required principles. This facilitates the qualification grade of works to be carried out at factories functioning as en-terprises with higher risk. The flow rates measurements are conducted at operational conditions by indirect method of dynamic gauging of volumetric flow rate and gas volume with ultrasonic flow transducer. Functioning principle of equipment bases on connection of differences in time of flight of ultrasonic impulse with and against gas flow between sound detectors from an aver-age velocity of gas stream along acoustic path. Acceptable relative expanded uncertainty of flow rate measurements for “A” accuracy level constitutes 0,3% for operational conditions that exceeds the resulted value, which is determined by the unac-counted errors for the suggested method. This heavily traceable error lies in systematical inaccuracy during calibration of de-vice. Among other things are liquid droplets occurring in the flow, low acoustic resistance of gas and high rate of sound absorp-tivity and low valuable signal, which is caused by prevailing sound velocity comparing with flow velocity. The technique of sug-gested uncertainty evaluation is applicable for facilities extracting and treating gas and condensate at shore and offshore fields as well. In the case, the homogeneity of measured flow obtained by separation is the most affecting factor of successful evalua-tion. For prevention of interfering factors, the gauge is recommended to fix after the treating facilities at the pipes with gas flow and to make pigging of inner surface on due time.


Keywords: gas flow measuring, uncertainty, standard conditions, ultrasonic transducer

References

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Reference:
 Vladymyrova, T.M. and Shalabanova, M.S. (2018), “Otsenka neopredelennosty rezultatov yzmerenyi raskhoda haza ultrazvukovыmy preobrazovateliamy” [Uncertainty evaluation of gas flow rate measurements by ultrasonic transducer], Information Processing Systems, Vol. 4(155), pp. 84-91. https://doi.org/10.30748/soi.2018.155.11.