8 replies to this topic

[sn_sn]

There is one control valve upstream of vessel. and PSV(set at 24 barg) installed to the vessel. during failure expected flow is 1945000 kg/hr. Normal condition is 17.7 barg and -97degC. i have calculated volume of vessel and piping inventory. how to calculate process safety time?

[breizh]

Hi,

Don't duplicate posts! please delete one of them.

What do you mean by "process safety time"?  

Breizh

[fallah]

There is one control valve upstream of vessel. and PSV(set at 24 barg) installed to the vessel. during failure expected flow is 1945000 kg/hr. Normal condition is 17.7 barg and -97degC. i have calculated volume of vessel and piping inventory. how to calculate process safety time?

Hi,

 

Is control valve failure leading to happening a dangerous situation or the PSV can handle the case?

Is there any SIF for prevention of the happening a dangerous case?

 

It's important the SIF response to be faster than the PST....

[latexman]

Isn’t it the time to go from 17.7 to 24 barg? I suggest you review unsteady-state mass balances. Do you have Felder and Rousseau’s Elementary Principles of Chemical Processes.

[sn_sn]

CUrrently 4 PSVs intslled but it can't handle the flow once we upgrade the system. so planning to povide shutdown valve upstream of control valve to stop the flow and for that need to find out time to reach from 17.7 Bar to 24 Bar

[sn_sn]

i don't have Felder and Rousseau's elemetary principles

Edited by sn_sn, 20 November 2022 - 08:02 PM.

[breizh]

Hi,

1) You know your initial condition (Pi,Ti), you can calculate the number of moles within this volume,

2) You know your final condition (Pf,Tf), same calculation.

The difference (2-1) divided by the molar flowrate will give you the time you are looking for.

My 2 cents

Breizh 

[latexman]

i don't have Felder and Rousseau's elemetary principles

Then, use your university text that covered material balances, or another reference, that you do have. Besides, breizh has nailed it for you.

[sn_sn]

worked what Breizh suggested...thank you everyone

Edited by sn_sn, 23 November 2022 - 08:24 PM.