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Chemical Process Technology

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Sunday, December 20, 2009

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Pressure safety valve (PSV) or pressure relief valve (PRV) is commonly used to protect a pressure containment part i.e. vessel, column, etc from overpressure. It is one of the code approved type of overpressure protection devices. This type of device is reclosing type where the mechanism of devices is designed such that it will stop relief when the pressure is reduced to it reseat pressure. Besides PSV, rupture disc (RD) and rupture pin are also code approved type of overpressure devices. This type of device is non-reclosing type where it will continue to relief until all inventory is completely evacuated from the system or with operator intervention.

Earlier post "Visualise Pressure Safety Valve (PSV) Assemblies & Operation" presented some features about the PSV type and also a video clip for typical construction and operation of a conventional PSV. This post will present PSV valve disc movement and flow distribution inside a PSV.

PSV valve disc movement and flow distribution inside a PSV is simulated using CFD modeller, CFX 11.0 . Following video clip shows how a spring loaded pressure relief valve works under over-pressure condition.




You may notice that high mass flux is on the disc facing PSV outlet nozzle.

Following is another video clip shows oscillating movement of PSV disc during relieving condition.






Above oscillating movement generate a oscillating forward flow which is believe one of the cause for valve chattering. Read more about PSV chattering in "PSV Chaterring is Destructive...The ways to Prevent...".

Thanks to Songxguan

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posted by Webworm, 7:12 AM

2 Comments:

Blogger xueguan said...

i'm songxguan,
contact me via songxguan@gmail.com.

January 14, 2010 at 12:00 AM  
Blogger xueguan said...

i'm songxguan,
contact me via songxguan@gmail.com.

January 14, 2010 at 12:01 AM  

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