Coriolis frequency tracking

Patent metadata

Field	Value
Publication number	US-10876875-B2
Application number	US-201815959422-A
Country	US
Kind code	B2
Filing date	Apr 23, 2018
Priority date	Mar 7, 2007
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

Motion is induced in a conduit such that the conduit vibrates in a major mode of vibration having a major amplitude and a minor mode of vibration having a minor amplitude. The major amplitude is larger than the minor amplitude, the major mode of vibration has a first frequency of vibration and the minor mode of vibration has a second frequency of vibration, and the minor mode of vibration interferes with the major mode of vibration to cause a beat signal having a frequency related to the first frequency of vibration and the second frequency of vibration. The frequency of the beat signal is determined, and the second frequency of vibration is determined based on the determined frequency of the beat signal.

First claim

What is claimed is:

1. A method of operating a Coriolis meter, the method comprising:
driving motion of a conduit to produce a driven mode of vibration in the conduit;
flowing fluid through the conduit while it is vibrating in the driven mode, the flowing fluid producing a Coriolis mode vibration;
sensing motion of the conduit at a first position using a first sensor outputting a first sensor signal;
sensing motion of the conduit at a second location different from the first location using a second sensor outputting a second sensor signal;
determining a mass flow rate of the fluid flowing through the conduit using a phase difference between the first and second sensor signals; and
using a beat frequency produced by interaction between the driven mode and Coriolis mode to determine a frequency of the Coriolis mode vibration.

2. A method as set forth in claim 1 further comprising determining a beat signal by analyzing amplitudes of the first and second sensor signals, the beat frequency being the frequency of the beat signal.

3. A method as set forth in claim 2 further comprising determining the beat frequency by: (i) determining a first time at which the amplitude of the beat signal has a predefined value and a second time at which the amplitude of the beat signal has the predefined value; (ii) determining a difference between the first and second times; and (3) determining the beat frequency based on said difference.

4. A method as set forth in claim 3 wherein the predefined value is zero.

5. A method as set forth in claim 3 wherein the first and second time comprises nonconsecutive occurrences of the predefined value.

6. A method as set forth in claim 1 further comprising determining a frequency of the driven mode, wherein using the beat frequency to determine the frequency of the Coriolis mode comprises determining a difference between the beat frequency and the frequency of the driven mode.

7. A Coriolis flowmeter transmitter comprising:
at least one processing device; and
a storage device, the storage device storing instructions adapted to cause the at least one processing device to:
drive motion of a conduit to produce a driven mode of vibration in the conduit;
receive a first sensor signal from a first sensor, the first sensor being positioned to sense motion of the conduit at a first position;
receive a second sensor signal from a second sensor, the second sensor being positioned to sense motion of the conduit at a second location different from the first location;
determine a mass flow rate of a fluid flow through the conduit using a phase difference between the first and second sensor signals; and
use a beat frequency produced by interaction between the driven mode and a Coriolis mode vibration to determine a frequency of the Coriolis mode vibration, the Coriolis mode vibration arising from forces associated with flow of fluid through the conduit while the conduit is being vibrated in the driven mode.

8. A Coriolis flowmeter transmitter as set forth in claim 7 wherein said instructions are further adapted to cause the at least one processing device to determine a beat signal by analyzing amplitudes of the first and second sensor signals, the beat frequency being the frequency of the beat signal.

9. A Coriolis flowmeter transmitter as set forth in claim 8 wherein said instructions are further adapted to cause the at least one processor to determine the beat frequency by: (i) determining a first time at which the amplitude of the beat signal has a predefined value and a second time at which the amplitude of the beat signal has the predefined value; (ii) determining a difference between the first and second times; and (3) determining the beat frequency based on said difference.

10. A Coriolis flowmeter transmitter as set forth in claim 9 wherein the predefined value is zero.

11. A Coriolis flowmeter transmitter as set forth in claim 9 wherein the first and second time comprises nonconsecutive occurrences of the predefined value.

12. A Coriolis flowmeter transmitter as set forth in claim 7 wherein said instructions are further adapted to cause the at least one processing device to determine a frequency of the driven mode, wherein using the beat frequency to determine the frequency of the Coriolis mode comprises determining a difference between the beat frequency and the frequency of the driven mode.

13. A method of operating a Coriolis meter, the method comprising:
driving motion of a conduit to produce a driven mode of vibration in the conduit;
flowing fluid through the conduit while it is vibrating in the driven mode, the flowing fluid producing a Coriolis mode vibration when the fluid is flowing through the conduit, the Coriolis mode of vibration arising from forces associated with the fluid flowing through the conduit while the conduit is being driven in the driven mode of vibration;
sensing motion of the conduit at a first position using a first sensor outputting a first sensor signal;
sensing motion of the conduit at a second location different from the first location using a second sensor outputting a second sensor signal;
determining a frequency of the Coriolis mode of vibration based on a beat frequency produced by interaction between the driven mode of vibration and the Coriolis mode of vibration while the conduit is being driven and the fluid is flowing through the conduit; and
determining a mass flow rate of the fluid flowing through the conduit based on the determined frequency of the Coriolis mode of vibration.

14. A method as set forth in claim 13 further comprising determining a beat signal by analyzing amplitudes of the first and second sensor signals, the beat frequency being the frequency of the beat signal.

15. A method as set forth in claim 14 further comprising determining the beat frequency by: (i) determining a first time at which the amplitude of the beat signal has a predefined value and a second time at which the amplitude of the beat signal has the predefined value; (ii) determining a difference between the first and second times; and (3) determining the beat frequency based on said difference.

16. A method as set forth in claim 15 wherein the predefined value is zero.

17. A method as set forth in claim 15 wherein the first and second time comprises nonconsecutive occurrences of the predefined value.

18. A method as set forth in claim 13 further comprising determining a frequency of the driven mode, wherein using the beat frequency to determine the frequency of the Coriolis mode comprises determining a difference between the beat frequency and the frequency of the driven mode.

Assignees

• Schneider Electric Systems Usa Inc

Inventors

• Henry Manus P
• Duta Mihaela D
• Tombs Michael S

Classifications

• G01F1/8436

  signal processing · CPC title

• G01F1/849 Primary

  having straight measuring conduits · CPC title

• G01F15/024

  involving digital counting · CPC title

• G01N9/002

  using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence) · CPC title

• G01F1/8486

  with multiple measuring conduits · CPC title