Methods for managing flow control valves in process systems

• US 7,606,636 B2
• Filed: 01/31/2007
• Issued: 10/20/2009
• Est. Priority Date: 01/31/2007
• Status: Expired due to Fees

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Dykstra, Jason D.
• Primary Examiner(s): DeCady; Albert
• Assistant Examiner(s): Sivanesan; Sivalingam
• Application Number:
  US11/700,533
• Publication Number:
  US 20080183336A1
• Time in Patent Office: 993 Days
• Field of Search: 702/85, 702/94, 702/100, 702/98, 700/29, 700/282, 700/295, 700/32
• US Class Current: 700/282
• CPC Class Codes: G05B 13/041 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 23/0283 Predictive maintenance, e.g. involving the monitoring of a system and, based on the monitoring results, taking decisions on the maintenance schedule of the monitored system; Estimating remaining useful life [RUL] preventive maintenance, i.e. planning maintenance according to the available resources without monitoring the system G06Q10/06
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence

Abstract

Methods 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 method for managing the operational condition of a flow control valve in a process system, comprising;

(a) regulating the flow rate of a flow stream with a flow control valve acting on said flow stream;

(b) determining in real-time the present value of the dead band of said valve using a non-linear dynamic model to model flow through the valve; and

(c) updating the controller providing the control signal to said control valve based at least on the results of action (b).

2. The method of claim 1 wherein action (b) further comprises determining in real-time the present value of the flow coefficient of said valve.

3. The method of claim 1 further comprising performing maintenance on said valve to at least reduce dead band to an acceptable value based on an output of the results of action (b) that indicates excess dead band.

4. The method of claim 1 wherein said action (b) uses non-linear equation modeling or neural network modeling to determine said present value of said dead band.

5. The method of claim 2 wherein an adaptive parametric controller is used to determine said present value of said flow coefficient.

6. The method of claim 1 wherein action (b) further comprises dynamically reducing the error in said determination of said present value of said dead band by reducing the error in the model and driving the modeled parameters to actual values.

7. The method of claim 1 wherein said action (b) uses a density observer or a volumetric observer.

8. The method 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 glove 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.

9. The method 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.

10. A method for performing predictive maintenance on a flow control valve in a process flow stream, comprising:

(a) determining in real-time the present value of the dead band of a flow control valve being used to regulate the flow rate of a flow stream without taking said valve off-line from acting on said flow process stream based on a non-linear dynamic model to model flow through the valve; and

(b) performing maintenance on said valve based at least on (a) to at least reduce dead band to an acceptable value, wherein the value indicates excess dead band.

11. The method of claim 10 further comprising determining in real-time the present value of the flow coefficient of said flow control valve without taking said valve off-line from acting on said flow process stream;

and performing action (b) based also on said present value of said flow coefficient.

12. The method of claim 10 wherein said action (a) uses non-linear equation modeling or neural network modeling in determining said present value of said dead band.

13. The method of claim 11 wherein an adaptive parametric controller is used in determining said present value of said flow coefficient.

14. The method of claim 10 wherein action (a) further comprises dynamically reducing the error in determining said present value of said dead band by reducing the error in the model and driving the modeled parameters to actual values.

15. The method of claim 10 wherein said action (a) uses a density observer or a volumetric observer.

16. The method of claim 10 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 glove 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.

17. The method of claim 10 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.

18. A method for controlling the flow rate of a flow stream, comprising:

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

(b) determining the present flow rate of said flow stream by non-linear dynamic modeling to model the flow through the valve;

(c) determining the present dead band of said valve based at least on actions (a) and (b);

(d) determining the present flow coefficients of said valve based at least on actions (a), (b), and (c); and

(e) updating a flow valve control algorithm at a controller providing said control signal to said control valve based at least on the results of actions (c) and (d).

19. The method of claim 18 wherein said action (d) is based on:

(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).

20. The method of claim 18 wherein said flow rate is determined using a sensor is selected from the group consisting of a Coriolis flow meter, a turbine meter, a pitot tube flow meter, and an orifice flow meter.