Systems for managing flow control valves in process systems

• US 20080183310A1
• Filed: 01/31/2007
• Published: 07/31/2008
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Dykstra, Jason D.
• Granted Patent: US 7,636,614 B2
• Time in Patent Office: Days
• US Class Current: 700/29
• CPC Class Codes: G05B 13/041 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 17/02 electric
• CPC Class Codes: G05B 23/0254 based on a quantitative model, e.g. mathematical relationships between inputs and outputs; functions: observer, Kalman filter, residual calculation, Neural Networks

Abstract

Systems for managing the operational condition of flow control valves in process systems. As a control valve experiences mechanical wear during operation, the physical changes to the valve can alter its dead band and flow coefficient. A non-linear dynamic model determines the present dead band by modeling the relationship between the actual flow through the valve and the commanded drive signal to the valve. The present valve flow coefficient can be determined by removing the dead band from the drive signal and using that modified signal in a flow rate model for the valve to adaptively find the flow coefficient value which matches the predicted flow from the flow rate model to the present measured flow from a flow rate sensor. The present dead band and flow coefficient can be used to update valve control algorithms and to make valve maintenance decisions.

Claims

1. A system for managing the operational condition of a flow control valve in a process system, comprising:

a flow control valve acting on a flow stream;

a sensor configured to measure the flow rate of said flow stream;

a non-linear dynamic model for determining the present value of the dead band of said control valve based at least on the control signal to said control valve and the flow measurement of said sensor; and

an output of said present dead band value as an indication of the operational condition of said valve.

2. The system of claim 1 further comprising:

an adaptive parametric controller for determining the present value of the flow coefficient of said control valve based at least on a flow model of said valve and said flow rate measured by said sensor; and

said output is further comprised of said present flow coefficient value as an indication of the operational condition of said valve.

3. The system of claim 1 further comprising a flow rate controller acting on said control valve to regulate the flow rate of said flow stream.

4. The system of claim 1 wherein said output is used as a basis for performing maintenance on said valve.

5. The system of claim 3 wherein said output is used to update said process flow rate controller.

6. The system of claim 1 wherein said non-linear dynamic model consists of a neural network model and/or non-linear equations.

7. The system of claim 1 wherein said non-linear model dynamically reduces the effects of analog-to-digital quantization in said determination of said present value of said dead band.

8. The system of claim 1 further comprising a density observer and/or a volumetric observer.

9. The system of claim 1 wherein said flow control valve is selected from the group consisting of a rotary-actuated control valve, a vertically-actuated control valve, an actuated metering valve, an actuated gate valve, an actuated ball valve, an actuated globe valve, an actuated diaphragm valve, a variable rate dump valve, a rotary valve, a rotary vane valve, a rotary pocket valve, a variable rate slide gate valve, or various combinations thereof.

10. The system of claim 1 wherein said flow rate is of a type selected from the group consisting of fluid flow rate, liquid flow rate, solid flow rate, gas flow rate, slurry flow rate, and multiphase fluid flow rate, or various combinations thereof.

11. A system for managing the operational condition of a flow control valve in a process system, comprising:

a flow control valve acting on a flow stream;

a sensor configured to measure the flow rate of said flow stream;

a computer system connected to said valve and said sensor; and

configured to provide;

non-linear dynamic modeling of the present value of the dead band of said valve based at least on the control signal to said valve and the flow rate measured by said sensor; and

an output of said present dead band value as an indication of the operational condition of said flow control valve.

12. The system of claim 11 wherein:

said computer system is further configured to provide an adaptive parametric computation of the present value of the flow coefficient of said valve based at least on a flow model of said valve and said flow rate measured by said sensor; and

said output is further comprised of said present flow coefficient as an indication of the operational condition of said flow control valve.

13. The system of claim 11 further comprising a flow rate controller acting on said control valve to regulate the flow rate of said flow stream.

14. The system of claim 13 wherein said output is used to update said process flow rate controller.

15. The system of claim 11 wherein said output is used as a basis for performing maintenance on said valve.

16. The system of claim 11 wherein said non-linear dynamic modeling is performed using a neural network model and/or non-linear equations.

17. The system of claim 11 wherein said non-linear dynamic modeling reduces the effects of analog-to-digital quantization in said determination of said present value of said dead band.

18. The system of claim 11 wherein said computer system is further configured to include a density observer and/or a volumetric observer.

19. A system for controlling the flow rate of a flow stream, comprising:

a flow control valve acting on a flow stream;

a computer system connected to said valve and said sensor; and

configured to provide;

(i) a control signal to a flow control valve acting on a flow stream;

(ii) a determination of the present flow rate of said flow stream;

(iii) a determination of the present dead band of said valve based at least on (i) and (ii);

(iv) a determination of the present flow coefficient of said valve based at least on (i), (ii), and (iii); and

(v) an update to a controller providing said control signal to said control valve based at least on the results of actions (iii) and (iv).

20. The system of claim 19 wherein said computer system is further configured to provide the results of (iv) by:

(i) removing said present dead band from said control signal;

(ii) calculating a value for the present flow based on action (i) using a flow model of said valve; and

(iii) determining said present flow coefficient with an adaptive parametric computation by manipulating said coefficient within said flow model with reference to the results of action (b).