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Relief Load Calculation For Full Of Liquid System

3 replies to this topic
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#1 Sevail

Sevail

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Posted 21 November 2017 - 12:28 AM

Dears,

My question is about the relief load calculation in the vessel which full of liquid and containing hydrocarbon and aqueous phases.

In extraction column (LPG treatment, MEROX unit) which is full of liquid and containing LPG and caustic, if the Low interface level of LPG and caustic is above 7.62 m from the grade, Due to vessel does not have any wetted wall by LPG exposed directly to the external fire, can I ignore the LPG relief rate and it is enough to report relief load for aqueous phase? If not, how can I calculate the relief load for LPG?

#2 fallah

fallah

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Posted 22 November 2017 - 01:54 AM

My question is about the relief load calculation in the vessel which full of liquid and containing hydrocarbon and aqueous phases.

In extraction column (LPG treatment, MEROX unit) which is full of liquid and containing LPG and caustic, if the Low interface level of LPG and caustic is above 7.62 m from the grade, Due to vessel does not have any wetted wall by LPG exposed directly to the external fire, can I ignore the LPG relief rate and it is enough to report relief load for aqueous phase? If not, how can I calculate the relief load for LPG?

Sevail,

The heat transfer rate between the aqueous phase and LPG layer by convection wouldn't be lower than the heat transfer rate through the vessel wall. Hence, although the wetted wall of LPG layer isn't among the wetted wall subjected to the fire envelope; the LPG layer will sense the fire heat and will corporate in relieving vapors due to the fire case.

IMO, a proper and, of course, conservative way for relief load determination in your case is selecting the higher relief load between two cases: one case assuming the vessel full of aqueous phase and another case supposing the vessel full of LPG with the same other conditions for both cases.

#3 Sevail

Sevail

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Posted 22 November 2017 - 03:45 AM

Dear  Mr. Fallah

Would you please let me know the complete title of referring paper in your post (IMO)?

Thanks.

#4 fallah

fallah

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Posted 22 November 2017 - 03:50 AM

Would you please let me know the complete title of referring paper in your post (IMO)?

Sevail,

No referring paper and it's just my opinion (IMO: in my opinion).