System and method for quantitative verification of flow measurements

Abstract

A flow meter system and method measures fluid flow in a conduit. The conduit has a conduit axis. The flow meter includes a sensor configured to provide measurement data relating to the volumetric or mass flowrate though the conduit, and a processor configured to determine flow per unit time in the conduit using the measurement data, an uncertainty measurement per unit time using the measurement data, and an uncertainty quantity using the uncertainty measurement per unit time. The uncertainty quantity is totaled over a time period.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of and priority to U.S. Application Ser. No. 63 / 114,407 filed Nov. 16, 2020, by Otto and Brown incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]The present disclosure is related to an electronic flow meter or electronic flow measurement device. Flow meters include, but are not limited to, ultrasonic flow meters, Coriolis flowmeters, electromagnetic flowmeters, thermal mass flow meters and differential pressure flow meters. U.S. Pat. Nos. 9,304,024, 10,288,462 and 10,393,568 and United States Patent Application Publication No. 2015 / 0198470 A1, entitled, “Self-Checking Flow Meter and Method” describe electronic flow meters and are incorporated herein by reference in their entireties. Electronic flow meters utilize measured sensor parameters to compute flow variables in real time. Some meters integrate the flow rate over a measurement cycle and aggregate the integrat...

AI Technical Summary

Benefits of technology

The patent is directed toward a self-checking ultrasonic flow meter that can estimate the accuracy of its measurement system by calculating the uncertainty of changes that could have affected the system. This estimate is obtained by measuring the velocity of fluid in multiple directions and comparing the measurements. The flow meter is designed to be able to detect changes in path angle and length caused by contamination build-up inside the meter body. The measurement is made using pairs of transducers arranged in a way that their paths have different angles or lengths, and the flow meter may have more than three measures in each direction. This design ensures accurate flow measurement and reduces the need for mechanical flow conditioning.

Problems solved by technology

Although qualitative diagnostics are useful, it can be difficult for the user of a flow meter to interpret these diagnostics, as they do not relate directly to the measurand.

Firstly, they can be designed to be non-intrusive, that is to present little blockage to the flow, and consequently produce insignificant pressure loss.

Secondly, their self-diagnostic capabilities and potential are attractive in applications where routine in-situ calibration is difficult for practical or cost reasons.

However, as these parameters are difficult to relate directly to the uncertainty of the flow measurement, the use of qualitative meter diagnostics alone is not presently regarded as wholly sufficient as a means of flow meter verification.

For example, in the 2003 edition of the Measurement Guidelines of the UK offshore oil and gas measurement regulator, while recognizing the benefits of current diagnostic techniques, note that they have the disadvantage that “diagnostic facilities are presently qualitative, rather than quantitative” [Department of Trade and Industry, Licensing and Consents Unit, Guidance Notes for Petroleum Measurement Under the Petroleum (Production) Regulations, December 2003, Issue 7].

A disadvantage of this design is that the single path meter is much more sensitive to distortions of the flow velocity field than the 4-path meter.

This difference in sensitivity means that when a difference is detected, there exists the possibility that the single path meter can be affected by a distortion of the flow field that has a negligible effect on the 4-path meter.

In the case where the four-path meter is used as the primary measurement, this could result in false alarms, i.e. the difference detected does not reflect a reduction in accuracy of the 4-path meter.

However, both of these arrangements suffer from a common weakness in that each group of four paths will still be affected differently by distortions of the flow velocity field, particularly when complex non-axial flow fields such as asymmetric rotational are present.

Whilst this has some use in diagnosing flow conditions, it complicates the process of meter verification, as it is difficult to distinguish between an error in the measurement system itself and a difference that is created by the flow velocity field.

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