Systems for managing flow control valves in process systems
First Claim
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 system;
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, wherein the non-linear dynamic model models flow through the valve to determine the present dead band value; and
an output of said present dead band value as an indication of the operational condition of said valve.
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Accused Products
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.
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Citations
20 Claims
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1. A system for managing the operational condition of a flow control valve in a process system, comprising;
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a flow control valve acting on a flow system; 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, wherein the non-linear dynamic model models flow through the valve to determine the present dead band value; and an output of said present dead band value as an indication of the operational condition of said valve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for managing the operational condition of a flow control valve in a process system, comprising:
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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; wherein the non-linear dynamic model models flow through the valve to determine the present dead band value and update a flow valve control algorithm. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A system for controlling the flow rate of a flow stream, comprising:
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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 modeling of the present dead band of said valve based at least on (i) and (ii); (iv) a modeling 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), wherein the modeling uses a non-linear dynamic model to model flow through the flow control valve and to update a flow valve control algorithm in the controller with the modeled present dead band value. - View Dependent Claims (20)
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Specification