Leak detector for process valve

Abstract

A leak detection system is described for detecting a leak through a closed valve disposed between an upstream pipe and a downstream pipe of an industrial process. An insertable plate is coupled to the valve in the pipe in-line with the fluid flow. A sensor couples to the flow and provides a signature output. A leak detector is coupled to the sensor and adapted to detect a leak through the valve based upon the signature output.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to valves in industrial processes, and more particularly, to detection and diagnosis of fluid leaks through closed valves. [0002] In the process control industry, automated control valves are used extensively to control process fluid mass flow and / or velocity in industrial processes. In some instances, especially in batch processes, it is necessary that a valve achieve a tight shut-off condition when it is closed. The phrase “tight shut-off” refers to a valve position wherein zero or near-zero fluid flows through the valve. In particular, a tight shut-off condition exists where no fluid flows through the valve, or where fluid flow is reduced to such a level that the flowing fluid had negligible impact the process. [0003] In industrial process where a tight valve shut-off condition is required, if the valve does not shut-off tightly, the resulting material leakage into a batch recipe can ruin the batch. If a tight shut-...

AI Technical Summary

Problems solved by technology

In industrial process where a tight valve shut-off condition is required, if the valve does not shut-off tightly, the resulting material leakage into a batch recipe can ruin the batch.

If a tight shut-off valve is leaking a noxious or toxic chemical, the leak can present a hazard for plant personnel and may result in an incident requiring involvement of the Environmental Protection Agency (EPA).

Both of these outcomes can be very expensive.

Unfortunately, seals fail for a variety of reasons, including corrosion, fouling, cavitation, physical wear and the like.

Corrosion typically erodes the seal creating surface imperfections that make a tight seal difficult to achieve.

Expansion of vapor pockets within the flow can cause metal erosion and eventual valve failure.

“Physical wear” refers to an instance where a seal is damaged during the valve closing process by pinching material between the valve plug and the valve seat or seal, thereby damaging the seat or seal body.

Finally, debris can also interfere with the seal or valve travel in general, thereby preventing tight valve shut-off.

Images