Hi shantanu.ghag,
1.
Q: Could anyone explain how temperature at PSV outlet nozzle stream is calculated?
A: What scenario that you are asking?
Q: Does it calculated based on back pressure?
A: The Temperature is calculated by flashing the Relief Pressure Stream to The Calculated Back Pressure at the PSV Outlet
Info: I have calculated PSV relief pressure based on back pressure calculation as per API 520 in flare header.
Response : I'm curious how you calculate the PSV Relief Pressure by calculating Back Pressure, The PSV Set Pressure shall be same as the Protected Equipment/Piping Design Pressure, depend on the scenarios the maximum accumulated pressure is add up from the set pressure. For Fire Case it is 21% accumulated pressure and 10% for other cases. Please Refer to API STD 521
2.
Q: I have seen in API 520 that temperature at relieving condition (PSV inlet) may be lower than operating temperature. how it can be?
A : What is the scenario? It is Possible Especially for Blocked Discharge Case, since the pressure is higher the stream is not flashed to lower pressure (opt pressure) but it is only flashed to set pressure. Please follow API STD 521 not 520
PSV Blocked Discharge Case.xlsx 14.12KB
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Edited by Erwin APRIANDI, 14 November 2019 - 02:34 AM.