Correcting frequency in flowtube measurements
AssigneeInvensys Systems, Inc.
InventorsManus P. Henry, Mayela E. Zamora
Life of this patent
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Abstract
Techniques are described for accurately measuring a density or other parameter of a fluid traveling through a vibratable conduit, using a flowmeter. The techniques involve obtaining measurements of a frequency of vibration of the conduit, as a function of a phase difference between two sensors measuring the vibration. Using the measurements, a corrected frequency corresponding to a zero phase difference can be estimated, and this corrected frequency can be used to perform density calculations. These techniques remove an undesirable dependency between the frequency/phase difference variables.
Claims17
A flowmeter comprising:
- a vibratable flowtube;
- a driver connected to the flowtube and operable to impart motion to the flowtube;
- a first sensor connected to a first portion of the flowtube and operable to sense a frequency of the motion of the flowtube and generate a first sensor signal;
- a second sensor connected to a second portion of the flowtube and operable to sense the frequency of the motion of the flowtube and generate a second sensor signal;
- and
- a controller operable to adjust the frequency sensed by the sensors based on a phase difference between the first sensor signal and the second sensor signal, to thereby obtain a corrected frequency;
- wherein the controller is operable to determine a relationship between the frequency and the phase difference, based on a plurality of frequency measurements and corresponding phase difference measurements, the relationship being determined using at least one of a linear regression and/or a quadratic fit based on the frequency measurements and phase difference measurements.
A method comprising:
- determining an operational parameter associated with an operation of a flowmeter;
- selecting a corrected frequency corresponding to the operational parameter, the corrected frequency determined based on a phase difference between a first sensor signal and a second sensor signal, and determined based on a relationship between a plurality of measured frequency values and a plurality of measured phase differences, the relationship being determined by using at least one of a linear regression and/or a quadratic fit based on the plurality of measured frequency values and the plurality of measured phase differences, where the first sensor signal and the second signal correspond to a frequency of vibration of a flowtube associated with the flowmeter;
- and
- determining a flow parameter of a material flowing through the flowtube, based on the corrected frequency.
A flowmeter controller comprising:
- a measurement system operable to receive a first sensor signal and a second sensor signal and determine a frequency of vibration of a flowtube having a material flowing therethrough, based on the first sensor signal and the second sensor signal;
- a frequency correction system operable to determine a corrected frequency of the flowtube corresponding to a zero phase difference between the first sensor signal and the second sensor signal, the frequency correction system further operable to determine the corrected frequency by establishing a relationship between a plurality of frequency measurements and a plurality of phase difference measurements output by the measurement system, the relationship being determined using at least one of a linear regression and/or a quadratic fit based on the plurality of frequency measurements and the plurality of phase difference measurements;
- and
- a flow parameter determination system operable to determine a flow parameter characterizing the material, based on the corrected frequency.
Dependencies are inferred from the claim text.