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Peak Flow Rate During De-Pressurization Is Function Of Initial System

depressurisation peak flow rate valve cv

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#1 Shailes1982

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Posted 29 August 2013 - 05:49 AM

Is peak flow rate during de-pressurization is function of initial system inventory (volume) if all other parameters like initial pressure, temp., composition, valve Cv, back pressure etc. are constant and only system inventory is different?

We have observed that less inventory  results in lower peak flow rate as compared similar system with large inventory. This applies to completely liquid filled as well as for vapor filled system.

Please share your observations and justification for the same



#2 PaoloPemi

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Posted 29 August 2013 - 06:07 AM

you forgot to mention constant depressuring time to obtain the same final pressure,

that granted, yes.



#3 flarenuf

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Posted 29 August 2013 - 09:24 AM

Shailes
 

i think a small clarification here is required .

 

1. if the temp, pressure, composition and  valve are all constant then the initial blowdown rate is independent of the inventory.
    flow is determined by Pupstream   Pdns  and port size.
What will happen here is that the inventory will depressurise in less than or more than 15 mins  down to required dP pressure depending on inventory being smaller or greater than design

 

2  if dP time is to be maintained at 15 mins then the port size must be altered

 

hope this clarifies

flarenuf



#4 PaoloPemi

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Posted 29 August 2013 - 10:19 AM

"if time is to be maintained at 15 mins then the port size must be altered"

 

correct



#5 fallah

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Posted 31 August 2013 - 01:57 PM

Shailes,

 

1- For the same depressurizing time and final pressure (in addition to keep other mentioned parameters constant), the peak flowrate and following that valve Cv are the functions of the initial system inventory...

 

2- The liquid filled systems don't normally need to be depressurized same as vapor (or two phase) filled systems...






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