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CN-122029404-A - Coriolis flowmeter with external magnetic field detection and related method

CN122029404ACN 122029404 ACN122029404 ACN 122029404ACN-122029404-A

Abstract

A coriolis flowmeter (5) and related method are provided. The pick-up zero point (PO zero ) is measured during no flow conditions through the flow conduit of the flowmeter. The flow material is caused to flow through the flow conduit, and a driver connected to the flow conduit oscillates the flow conduit in a first bending mode. Signals from a pick-up sensor connected to the flow conduit are received. The PO ratio (P or ) was measured. A percentage limit (PO limit ) is determined, wherein the percentage limit (PO limit ) includes an allowable deviation between the pick-up zero (PO zero ) and the PO ratio (P or ). The meter electronics is configured to set a flag state when a percentage difference between the pick-up ratio (P or ) and the pick-up zero (PO zero ) is greater than a percentage limit (PO limit ).

Inventors

  • Alec Brian Van Horn
  • Antony William pancratz

Assignees

  • 高准有限公司

Dates

Publication Date
20260512
Application Date
20231016

Claims (14)

  1. 1. A method for operating a coriolis flowmeter having meter electronics and a flow conduit, comprising: measuring a pick-up zero point (PO zero ) during no flow conditions through the flow conduit; flowing a flow material through the flow conduit; driving a driver connected to the flow conduit to oscillate the flow conduit in a first bending mode; Receiving a signal from a pick-up sensor connected to the flow conduit; measuring the PO ratio (Po r ); Determining a percentage limit (PO limit ), wherein the percentage limit (PO limit ) comprises an allowable deviation between the pick-up zero (PO zero ) and the PO ratio (PO r ); The meter electronics is configured to set a flag state when a percentage difference between the pick-up ratio (Po r ) and the pick-up zero (Po zero ) is greater than the percentage limit (Po limit ).
  2. 2. The method for operating a coriolis flowmeter of claim 1 further comprising indicating magnetic tampering if a flag state is set.
  3. 3. The method for operating a coriolis flow meter of claim 1 further comprising: measuring a drive gain percentage (DG % ) comprising an amount of power required to drive the flow tube to a specified amplitude; Providing a drive gain limit; wherein configuring the meter electronics further comprises configuring the meter electronics to indicate a transitional state instead of the flag state when the drive gain percentage (DG % ) exceeds the drive gain limit.
  4. 4. The method for operating a coriolis flow meter of claim 3 further comprising: calculating a standard deviation of the drive gain percentage (DG % ); providing a drive gain standard deviation limit (DG SDlimit ); Wherein configuring the meter electronics further comprises configuring the meter electronics to indicate a transitional state other than the flag state when a standard deviation of the drive gain percentage (DG % ) exceeds the drive gain standard deviation limit (DG SDlimit ).
  5. 5. The method for operating a coriolis flow meter of claim 1 further comprising: Measuring mass flow; Wherein configuring the meter electronics further comprises configuring the meter electronics to indicate a transitional state other than the flag state when the mass flow rate is less than or equal to zero.
  6. 6. The method for operating a coriolis flow meter of claim 1 further comprising: Averaging (Flag AVG ) the number of Flag states set for a predetermined time range; providing Flag limits (Flag limit ) including the average number limit of flags for the set time range, and If the average number of Flag states (Flag AVG ) is greater than the Flag limit (Flag limit ), magnetic tampering is indicated.
  7. 7. The method for operating a coriolis flowmeter of claim 1 further comprising triggering an alarm if magnetic tampering is indicated.
  8. 8. A coriolis flowmeter (5) comprising: A flow conduit (103 a,103 b) configured to receive a fluid flow; A driver (104) and a pick-up sensor (105, 105') connected to the flow conduits (103A and 103B); Meter electronics (20) configured to drive the driver (104) to oscillate the flow conduit (103 a,103 b) in a first bending mode and configured to receive signals from the pick-up sensor (105, 105'); A pick-up zero (PO zero ) measured during no-flow conditions and accessible by the meter electronics; A PO ratio (PO r ) measured during flow conditions and accessible by the meter electronics; A percentage limit (PO limit ) accessible by the meter electronics, wherein the percentage limit (PO limit ) comprises an allowable deviation between the pick-up zero (PO zero ) and the PO ratio (PO r ); Wherein the meter electronics (20) is further configured to set a flag state when a percentage difference between the pick-up ratio (Po r ) and the pick-up zero (Po zero ) is greater than the percentage limit (Po limit ).
  9. 9. The coriolis flowmeter (5) of claim 8, comprising an indicator, wherein the indicator is configured to indicate magnetic tampering if a flag state is set.
  10. 10. The coriolis flowmeter (5) of claim 8, wherein the meter electronics (20) is configured to measure the driver (104) and calculate a drive gain percentage (DG % ) comprising an amount of power required to drive the flow conduits (103A and 103B) to a specified amplitude; Providing, by the meter electronics, a drive gain limit; Wherein the meter electronics is configured to indicate a transitional state instead of the flag state when the drive gain percentage (DG % ) exceeds the drive gain limit.
  11. 11. The coriolis flowmeter (5) of claim 10, wherein the meter electronics (20) is configured to calculate a standard deviation of the drive gain percentage (DG % ); Wherein the meter electronics is configured to indicate a transitional state instead of the flag state when a standard deviation of the drive gain percentage (DG % ) exceeds a drive gain standard deviation limit (DG SDlimit ).
  12. 12. The coriolis flowmeter (5) of claim 8, wherein the meter electronics (20) is configured to measure a mass flow of the fluid flow in the flow conduit (103 a,103 b); Wherein the meter electronics is configured to indicate a transitional state instead of the flag state when the mass flow rate is less than or equal to zero.
  13. 13. The coriolis flowmeter (5) of claim 8, wherein the meter electronics (20) is configured to average (Flag AVG ) a number of Flag states set for a predetermined time range and to indicate magnetic tampering if the average number of Flag states (Flag AVG ) is greater than a Flag limit (Flag limit ).
  14. 14. The coriolis flowmeter (5) of claim 8, wherein the meter electronics (20) is configured to trigger an alarm if magnetic tampering is indicated.

Description

Coriolis flowmeter with external magnetic field detection and related method Technical Field The embodiments described below relate to vibration sensors, and more particularly, to a flow meter and related methods that can detect an external magnetic field. Background Vibration sensors such as, for example, vibrating densitometers and Coriolis (Coriolis) flowmeters are generally known and are used to measure mass flow and other information related to material flowing through a conduit in the flowmeter. Example coriolis flowmeters are disclosed in U.S. patent 4,109,524, U.S. patent 4,491,025, and reissue patent 31,450. These flow meters have a meter assembly with one or more conduits in either a straight or curved configuration. Each conduit configuration in a coriolis mass flowmeter, for example, has a set of natural vibration modes, which may be of the simple bending, torsion, or coupling type. Each catheter may be driven to oscillate in a preferred mode. When no flow is passing through the flow meter, the driving force applied to the conduit oscillates all points along the conduit with the same phase or with a small "zero offset", which is the time delay measured at zero flow. As material begins to flow through the conduit, the coriolis force causes each point along the conduit to have a different phase. For example, the phase at the inlet end of the flowmeter lags the phase at the centralized driver location, while the phase at the outlet leads the phase at the centralized driver location. The pickups on the catheter generate a sinusoidal signal representing the motion of the catheter. The signals output from the pickups are processed to determine what is known as between pickupsIs a time delay of (a) to (b). The time delay between two or more pickups is proportional to the mass flow of material flowing through the conduit. Meter electronics connected to the drive generates drive signals to operate the drive and also determines the mass flow and/or other characteristics of the process material based on the signals received from the pick-up. The driver may comprise one of many well known arrangements, however, magnets and opposing drive coils have met with great success in the flow meter industry. Alternating current is delivered to the drive coil to cause the conduit to vibrate at a desired conduit amplitude and frequency. It is also known in the art to provide the pick-up as a magnet and coil arrangement very similar to the drive arrangement. When a strong external magnet is placed near the pickup, some effects are observable. First, the pickup voltage will drop or increase rapidly. Second, the phase shift between pickups will drop or increase rapidly. Once the magnet is removed, the sensor voltage and phase shift returns to normal. In existing methods, only the ratio or difference of the pick-up signals is used to determine the presence of an external magnetic field. However, when two magnetic fields are present, the pick-up ratio changes less and is therefore more difficult to detect. There is a need for an apparatus and method for detecting a dual external magnetic field. Disclosure of Invention A method for operating a coriolis flowmeter having meter electronics and a flow conduit is provided. The method includes measuring a pick-up zero point (PO zero) during a no-flow condition through the flow conduit and flowing a flow material through the flow conduit while driving a driver connected to the flow conduit to oscillate the flow conduit in a first bending mode. A signal from a pick-up sensor connected to the flow conduit is received and the PO ratio (PO r) is measured. A percentage limit (PO limit) is determined, wherein the percentage limit (PO limit) includes an allowable deviation between the pick-up zero (PO zero) and the PO ratio (PO r). The meter electronics is configured to set a flag state when a percentage difference between the pick-up ratio (Po r) and the pick-up zero (Po zero) is greater than a percentage limit (Po limit). A coriolis flowmeter is provided. The coriolis flowmeter includes a flow conduit configured to receive a flow of fluid, a driver and pick-off sensor connected to the flow conduit, meter electronics configured to drive the driver to oscillate the flow conduit in a first bending mode and configured to receive a signal from the pick-off sensor, and a pick-off zero (PO zero) measured during a no flow condition and accessible by the meter electronics, a PO ratio (PO r) measured during the flow condition and accessible by the meter electronics, a percentage limit (PO limit) accessible by the meter electronics, wherein the percentage limit (PO limit) includes an allowable deviation between the pick-off zero (PO zero) and the PO ratio (PO r), and the meter electronics is further configured to set a flag state when a percentage difference between the pick-off ratio (PO r) and the pick-off zero (PO zero) is greater than the percentage limit (PO limit). Aspects of According to on