how to determine the leak inventory in the process leak calculation?

[driftshade]

dear guys,
does anyone know how to determine leak inventory in the process leak calculation?

backgroud:
the case is that i have choose four leak hose size(12in pipe with 4catagory hose size6.35mm,25mm,100mm,rupture(300mm)), i know,in the offshore fire and explosion analysis,the release inventory =isolated inventory in the segration+intial release inventory before ESD shut down-inventory blowout, now the operating pressure is 25bar，and the tempreture is 55 centigrade.during nomally operation condition,the max. flowrate in the pipe is 55.89kg/s, i choose the PHAST 6.53 to calculate the initial leak rate,‘leak model' for hole size of 6.35mm and 25mm,and long pipeline for 100mm,300mm,
but the inintial leak rate for large leak and rupure is very high,far bigger than 55.89kg/s, if i take the value ,the release inventory is so large,i think there's must be some problem,but i don't know why? i don't know whether my method to calculate method for release inventory is wrong, or i just need adjust the result if it's larger than the normally flowrate in the pipework?
pls. help me

thanks in advance.

[AfigueredoU]

I have to do some math, but yes, it could be possible at the end the gas leak flow results bigger than the line flow, thats means that all the inventory will be lost and part of the inlet flow too, until the ESD can close.

So dont be affraid that a leak could be bigger than the inlet, tha is how the leaks stops the process. If interesting in talk about that, let me know.

[driftshade]

I have to do some math, but yes, it could be possible at the end the gas leak flow results bigger than the line flow, thats means that all the inventory will be lost and part of the inlet flow too, until the ESD can close.

So dont be affraid that a leak could be bigger than the inlet, tha is how the leaks stops the process. If interesting in talk about that, let me know.

thanks afiguesredou,
if the ESD is shutdown,is it possible that the leak flow is bigger than the normally line flow??
did you know how to model medium and large leak using PHAST?

[Germante]

This occurs because the difference between atmospheric pressure and pipe. As the pressure decreases the discharge rate also makes it, until pressures are equalized.


Sorry for my English.

[safetyuser]

backgroud:
i choose the PHAST 6.53 to calculate the initial leak rate,‘leak model' for hole size of 6.35mm and 25mm,and long pipeline for 100mm,300mm,
but the inintial leak rate for large leak and rupure is very high,far bigger than 55.89kg/s, if i take the value ,the release inventory is so large,i think there's must be some problem,but i don't know why?

sure is too late for my reply, but maybe a suggestion for others.

For my opinion the difference could have been the use in PHAST of long pipeline model instead of a leak model from vessel: when use large hole sizes with long pipeline you should find about twice the expected rate since the leak occur from both left and right breaches in the pipeline.
If your release starts from an isolated condition then a transient modelling could be well modelled with leak from vessel.

I'm interested in this topic: driftshade, could you post the solution you found for your problem and your explanation?