Coriolis mode processing techniques

Patent metadata

Field	Value
Publication number	US-9618374-B2
Application number	US-201314046710-A
Country	US
Kind code	B2
Filing date	Oct 4, 2013
Priority date	Jul 11, 2005
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

Flowmeters are described in which a sensor signal received from a sensor that is attached to vibratable flowtube, so as to determine properties of a fluid within the flowtube, contains a drive signal component and a Coriolis mode component. The flowmeters are operable to determine drive parameters of the drive signal component, as well as Coriolis parameters of the Coriolis mode component. By analyzing the sensor signal based on the drive signal parameters, and not on the Coriolis signal parameters, the flowmeters are able to provide stable and accurate determinations of the properties of the fluid.

First claim

What is claimed is:

1. A Coriolis flowmeter comprising:
a flow tube for containing a fluid flow;
a driver configured to induce motion of the flowtube;
a pair of sensors positioned to detect motion of the flowtube;
a processor configured to receive signals from the sensors and process the signals to measure a flow rate of fluid through the flow tube using a numerical integration of at least one of the sensor signals and to generate a drive signal, the driver being operatively connected to the processor to receive the drive signal,
wherein the signals received from the sensors include a drive mode component and a contaminant component arising from the natural frequency of the Coriolis vibrational mode, the contaminant component causing the sensor signal to have an observed zero crossing that is displaced in time from a true zero crossing of the drive mode component by a time offset, the processor being configured to set a limit for said numerical integration that accounts for said time offset and to use the numerical integration with said limit to generate the drive signal and maintain a desired oscillation of the flowtube based on the numerical integration.

2. A Coriolis flowmeter as set forth in claim 1 wherein said numerical integration is a step in a Fourier analysis of the at least one sensor signal.

3. A Coriolis flowmeter as set forth in claim 2 wherein the processor is configured to perform Fourier analysis on both sensor signals.

4. A Coriolis flowmeter as set forth in claim 1 wherein the processor is configured to estimate a major frequency of vibration of the flowtube using zero crossings of said at least one sensor signal.

5. A Coriolis flowmeter as set forth in claim 1 wherein the processor is configured to reduce the influence of the natural frequency of the Coriolis vibrational mode without producing an associated reduction in dynamic response of the flowmeter.

6. A Coriolis flowmeter as set forth in claim 1 further comprising a low pass filter that filters the sensor signals before they are used to measure the fluid flow rate, the low pass filter having a cutoff frequency higher than the natural frequency of the Coriolis mode vibration.

7. A Coriolis flowmeter as set forth in claim 1 wherein the processor is configured to output a first characterization of the sensor signals and a second characterization of the sensor signals, the influence of the drive mode component being emphasized relative to the contaminant component in the first characterization of the sensor signals, the influence of the contaminant component being emphasized relative to the drive mode component in the second characterization of the sensor signals.

8. A Coriolis flowmeter as set forth in claim 7 wherein said numerical integration is a first numerical integration and the processor is configured to use a second numerical integration, the processor being configured to use the first integration to obtain said first characterization of the sensor signals and to use the second integration to obtain said second characterization of the sensor signals.

9. A Coriolis flowmeter as set forth in claim 1 wherein said numerical integration is conducted over a time period related to an estimated frequency of the contaminant mode component.

10. A Coriolis flowmeter as set forth in claim 1 wherein the processor is configured to reduce the influence of the contaminant mode on the measured flow rate independent of any filtering of said at least one sensor signal by a filter configured to suppress a natural frequency of the Coriolis vibrational mode before said numerical integration.

Assignees

• Invensys Sys Inc

Inventors

• Henry Manus P

Classifications

• G01F1/74 Primary

  Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid · CPC title

• G01F1/84 Primary

  Coriolis or gyroscopic mass flowmeters · CPC title

• G01F1/76

  Devices for measuring mass flow of a fluid or a fluent solid material · CPC title

• G01F1/8486

  with multiple measuring conduits · CPC title

• G01F1/8436

  signal processing · CPC title