METHOD AND APPARATUS FOR CHARACTERIZING PROCESS CONTROL EQUIPMENT INTEGRITY

• US 20120274333A1
• Filed: 04/19/2012
• Published: 11/01/2012
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Original Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Inventors: Anderson, Shawn W.
• Granted Patent: US 9,000,773 B2
• Time in Patent Office: Days
• US Class Current: 324/511
• CPC Class Codes: G01N 29/09 by measuring mechanical or acoustic impedance
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/245 Ceramic probes, e.g. lead zirconate titanate [PZT] probes
• CPC Class Codes: G01N 29/2475 Embedded probes, i.e. probes incorporated in objects to be inspected
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/4427 with stored values, e.g. threshold values
• CPC Class Codes: G05B 19/0428 Safety, monitoring G05B19/0423 takes precedence
• CPC Class Codes: G05B 23/0224 Process history based detection method, e.g. whereby history implies the availability of large amounts of data

Abstract

In a process plant, a first series of impedance measurements from a valve body are received. The first series of impedance measurements are stored. A second series of impedance measurements from the valve body are received. The second series of impedance measurements from the valve body are stored. The first series and second series of impedance measurements are compared. An indication of loss of integrity of the valve body is generated if the first series of impedance measurements deviates from the second series of impedance measurements.

Claims

1. A method implemented at a fault detection and isolation (FDI) system for indicating loss of integrity of a body of a field device, the method comprising:

receiving at the FDI system a first series of measurements from the field device;

storing the first series of measurements;

receiving at the FDI system a second series of measurements from the field device;

storing the second series of measurements;

comparing the first series of measurements and the second series of measurements;

generating an indication if the first series of measurements deviates from the second series of measurements.

2. The method of claim 1, wherein the first series of measurements and the second series of measurements comprise impedance measurements.

3. The method of claim 1, wherein the first series of measurements and the second series of measurements comprise acoustic measurements.

4. The method of claim 2, wherein the first series of impedance measurements and the second series of impedance measurements are made using a plurality of electrical signals at a plurality of frequencies, the impedance measurements made in response to the FDI transmitting a first request for the first series of impedance measurements and a second request for the second series of impedance measurements.

5. The method of claim 4, wherein transmitting the first request and the second request includes transmitting an indication of at least one of the plurality of frequencies.

6. The method of claim 4, wherein each of the plurality of frequencies range from 30 Kilohertz (KHz) to 400 KHz.

7. The method of claim 4, including applying the plurality of electrical signals to the valve body through a piezoelectric (PZT) sensor.

8. The method of claim 7, including bonding the PZT sensor to the valve body near the valve body closure member.

9. The method of claim 7, including bonding the PZT sensor to the valve body with an adhesive.

10. The method of claim 3, wherein the first series and the second series of acoustic measurements comprise measurements received from a PZT sensor in response to the FDI transmitting a first request for the first series of acoustic measurements and a second request for the second series of acoustic measurements.

11. The method of claim 1, further comprises generating a first curve based on the first series of measurements and a second curve based on the second series of measurements.

12. The method of claim 11, further comprises determining a first plurality of coefficients for the first curve and a second plurality of coefficients for the second curve.

13. The method of claim 12, further comprises comparing the first plurality of coefficients and the second plurality of coefficients to determine if the first series of measurements deviates from the second series of measurements.

14. An apparatus for detecting the loss of integrity of a body of a field device, the apparatus comprising:

a fault detection and isolation (FDI) system;

a sensor coupled to the body of the field device;

an excitation module electrically coupled to the sensor and

a measurement module electrically coupled to the sensor.

15. The apparatus of claim 15, wherein the sensor is a piezoelectric (PZT) sensor.

16. The apparatus of claim 16, wherein the PZT sensor is coupled to the body of the field device near a closure member of the field device with a bonding adhesive.

17. The apparatus of claim 16, wherein the excitation module is arranged to electrically excite the PZT sensor via the electrical coupling with an electrical signal at a selected frequency, wherein the selected frequency ranges from 30 Kilohertz (KHz) to 400 KHz.

18. The apparatus of claim 17, wherein the excitation module is arranged to receive an indication of the selected frequency from the FDI.

19. The apparatus of 18, wherein the measurement module is arranged to transmit data measured from the PZT sensor to the FDI.

20. A method for indicating loss of integrity of a body of a field device, the method comprising:

causing a fault detection and isolation (FDI) system to receive a first series of measurements, wherein each of the measurements of the first series of measurements is made at the body of the field device;

in response to receiving the first series of measurements, causing the FDI system to store the first series of measurements;

causing the FDI system to receive a second series of measurements, wherein each of the measurements of the second series of measurements is made at the body of the field device;

in response to receiving the second series of measurements, causing the FDI system to store the second series of measurements;

comparing the first series of measurements and the second series of measurements;

determining that the first series of measurements deviates from the second series of measurements; and

causing the FDI to generate an indication on determining that the first series of measurements deviates from the second series of measurements.

21. The method of claim 20, wherein the first series of measurements is received in response to causing the FDI system to transmit a first request for the first series of measurements and the second series of measurements is received in response to causing the FDI system to transmit a second request for the second series of measurements.

22. The method of claim 21, wherein each of the first request and the second request includes an indication of a selected frequency.

23. The method of claim 22, wherein each of the first series of measurements and the second series of measurements correspond to impedance measurements caused to be made at body of the field device by exciting a PZT sensor with an electrical signal at the selected frequency, wherein the PZT sensor is bonded to the body of the field device.