Method and equipment for determining the performance of control valve

• US 5,992,229 A
• Filed: 02/05/1996
• Issued: 11/30/1999
• Est. Priority Date: 02/05/1996
• Status: Expired due to Fees

• Current Assignee: Neles-Jamesbury OY (Neles Oyj)
• Original Assignee: Neles-Jamesbury OY (Neles Oyj)
• Inventors: Ylikoski, Esko, Pyotsia, Jouni
• Primary Examiner(s): HIRSHFELD, ANDREW HOWARD
• Application Number:
  US08/596,634
• Time in Patent Office: 1,394 Days
• Field of Search: 73/168, 364/528.17, 702/45, 702/113, 702/114, 702/33
• US Class Current: 73/168
• CPC Class Codes: F16K 37/0083 by measuring valve parameters
• CPC Class Codes: G05B 17/02 electric

Abstract

A method for determining the performance of a control valve in a closed control loop by using a simulation model. A simulation model of a process control loop is provided, consisting of a unit process (2) including the flow equations of the valve, a process controller (4) and a process transmitter (3), to simulate a process with disturbances (6, 6'"'"'). The simulation model is connected to a real control valve (1), including a valve, an actuator and a positioner. The valve response is measured. The process variability during the process is determined.

Claims

1. A method for determining the performance of a control valve assembly in a closed control loop, said method comprising:

a) selecting a mathematical part of a simulation model of a process control loop, the model including a process variable, flow equations for the control valve and pipeline behavior features, a process controller, and a process transmitter;

b) connecting the mathematical part of the simulation model to the control valve assembly having a control valve, an actuator and a positioner;

c) supplying actuating energy to the positioner;

d) measuring the valve position;

e) simulating a process control loop with disturbances; and

f) determining the process variability during the process, wherein the performance of the control valve assembly is evaluated as the process variability.

2. A method according to claim 1, said method further comprising:

providing a model library from which the simulation model is selected.

3. A method according to claim 2, wherein the model library includes models of at least some of the following models:

flow control loops, pressure control loops, temperature control loops, tank level control loops and blending loops.

4. A method according to claim 1, wherein a general disturbance characteristic to the control loop is used as the disturbances in the simulated process control loop.

5. A method according to claim 1, wherein disturbances measured from a real process control loop are used as the disturbances in the simulated process control loop.

6. Equipment for testing a control valve assembly, said equipment comprising:

a) a control valve assembly including a control valve, an actuator, a positioner and means for supplying actuating energy to the positioner;

b) a computer with an input and output card, the valve assembly being connected to the input and output card of the computer; and

c) an executable program which, when executed simulates a process with disturbances, the executable program including a mathematical part of a simulation model of a process control loop, the model including a process variable, flow equations for the control valve and pipeline behavior features, a process controller and a process transmitter, the executable program being executed on the computer.

7. Equipment according to claim 6 wherein the actuator is a double acting actuator and the positioner is a two-stage electromagnetic positioner with an I/P conversion inside a position feedback loop.