How to improve relieving rate calculation? 2

[Neyde]

Hi
I would like to know if someone has experience or has already used dynamic simulation to determine relief rate to design pressure safety valves.
The traditional methodology is based on simplified calculation, but this procedure can lead to over designing relief headers and flare systems. So, I think that dynamic simutation should be a good tool to improve relief rate estimation.

Thanks

Neyde

 

[krossview]

Neyde,

I highly recommend you do an "ADVANCED" search on the ENG-TIPS forums using keywords like "Oversized relief valves PSV dynamic flare headers" and you will find a lot of excellent discussions on this topic that probably answer 85% of your question. ;-)

 

[EGT01]

While looking for info on taking credit for dT suppression in reboilers, I came across this article that was rather helpful -

"Modeling of tower relief dynamics, Part 1", JRCassata, SDasgupta and SLGandhi (MWKellogg Co), Hydrocarbon Processing, October 1993.
Part2, November 1993.

 

[Neyde]

Hi krossview and EGT01

Thanks for the helpful tips. I have already read this article, it is very interesting.

Bye

Neyde

 

[Chandrasekar]

Neyde
Although theoratically dynamic simulation would provide you with moe accurate relief flows and an optimised line sizing, the economics of resources time and the benfits have to be weighed.
Assume you are required to design a new gas plant or a grassrot refinery or and LNG plant and the number of relief devices to be designed !
My beleif is to still use the time tested API calculations and spreadsheets.
Chandra

 

[MortenA]

I have done such calculations using a program called flowmaster - both as surge analysis for liquids and for gas blow-down.

Best Regards

Morten

 

[JAlton]

try digital solutions at

http://www.nvo.com/safetyrelief

J. Alton Cox
President
DeLuca Test Equipment

http://www.delucatest,com

 

[leguaych]

Hi,

This kind of component indeed has to be considered in dynamic (stability problems). I advice to have a look at the AMESim software. They have a solver dedicated to this problem and the company who develops the software is also a service company expert in fluid power. They have a nice library to design hydraulics components and study them (Linear analysis, modal shapes)

Hope this will help

 

[hduncan]

I've used Aspen Plus to size relief valves. It does a dynamic simulation of the valve--showing when the valve opens and closes. It would sometimes give a larger or smaller valve, depending on the scenario.