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DETECTION OF PASSING OR LEAKAGE OF A CONTROL VALVE

IP.com Disclosure Number: IPCOM000241594D
Publication Date: 2015-May-14
Document File: 5 page(s) / 172K

Publishing Venue

The IP.com Prior Art Database

Abstract

The disclosure proposes a technique for detecting leakage or passing of a control valve. A parallel plate capacitor is installed in a downstream section of a pipe of the control valve. The parallel plate capacitor maintains a fixed voltage across its plates. The capacitance of the capacitor increases when the liquid of the control valve enters the area of charged capacitor. Any change in the capacitance indicates a leakage of the control valve.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

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274288

DETECTION OF PASSING OR LEAKAGE OF A CONTROL VALVE

BACKGROUND

The present disclosure relates generally to control valves and more particularly to a technique for detecting leakage or passing of the control valves.

During normal plant operation leakage of the control valves will typically not occur. However, with passage of time, control valve leakage may occur and leak fluid into a section of a pipe downstream of the control valve. Such leakage may hamper the normal plant operations. Therefore, it is essential to monitor control valves for leakage.

One conventional technique utilizes Acoustic Emissions (AE) for detecting leakage of the control valves. Another conventional technique utilizes ultrasonic signals for detecting leakage of the control valves. However, such conventional techniques may be complex and require additional mechanisms for generating the acoustic signal and/or the ultrasound signals to detect the control valve leakage or passing. Further, such techniques may not be effective in detecting the control valve leakage within a plant.

It would be desirable to have a technique for detecting leakage or passing of the control valves.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 depicts an exemplary configuration, wherein a parallel plate capacitor is installed in an outgoing pipe for detecting leakage or passing of a control valve.

Figure 2 depicts a cross-sectional view of a pipe situated downstream of a control valve.

DETAILED DESCRIPTION

The disclosure proposes a technique for detecting leakage or passing of control valves.

Figure 1 depicts an exemplary configuration, wherein a parallel plate capacitor is installed in a downstream pipe for detecting leakage or passing of the control valve.

1


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274288

Operating Air  Pressure from  control pilot

HP steam

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Figure 1

A parallel plate capacitor is installed in a section of a pipe downstream of the control valve. The parallel plate capacitor has an area (A) and distance between the plates (also called electrodes) as d. The parallel plate capacitor maintains a fixed voltage across its plates. The capacitance of the parallel plate capacitor changes when liquid leaking out of the control valve enters the area of the charged parallel plate capacitor. A measurement, which may be periodic or continuous, of the capacitance helps in monitoring the leakage of the control valve.

Figure 2 depicts another exemplary embodiment of using capacitance to monitor control valve leakage into a pipe situated downstream of the control valve.

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274288

1

d=25 mm

Insulating material Capacitor plate

4 inch

2

3

Electrodes

Figure 2

There are three electrodes, such as 1, 2 and 3 arranged across a cross section of a pipe. The capacitance between electrodes 1 and 2 is defined as C1. Further, the capacitance between electrodes 1and 3 is defined as C2 and the capacitance between electrodes 2 and 3 is defined as C3. The distance between electrodes 2 and 3 may be 2...