Effect of System Volume on PSV cycling

[Sawsan311]

Dear All,

I am exploring the effect of system volume of PSV cycling, considering a larger vessel having a PSV set at a set pressure equal to another PSV installed on a smaller vessel, and considering the closing pressure is the same for both PSVs.. Do you agree that smaller vessels will have more frequent opening and closing of the PSV compared to the larger vessel specially if in both cases the actual capacity is less than 25% of the PSV rated capacity.

Note, the PSV size is the same in both cases

Thanks

 

[Latexman]

Yes.

Note, the PSV size is the same in both cases

Obviously, the answer is yes, but without any detail on the vessel sizes, I'm not sure of the usefullness of your assumption. In a fire case, that assumption probably would not be true. In cases of very large differences in system volume and non-fire cases, I find this difficult to believe as well.

Good Luck,
Latexman

 

[Sawsan311]

Hi Mr.Latexman,

Yes,I was mainly referring to non-fire contingencies since for fire scenarios obviously fire scenarios would either have a a larger liquid vaporization load (for light HC liquid case) or a larger gas expansion load (for heavy HC liquid or for liquids rich in water).

The reason of my question is to explore PSV cycling and chattering phenomena and since I read in the attached article that it depends on the mass balance of the system inventory at set pressure and closing pressure in comparison to the selected PSV rated capacity,

Regards,