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Temperature Change Inside Vessel During Depressurization - Assumptions

temperature depressurization blowdown orifice jt joule thompson

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#1 rs20170808@gmail.com

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Posted 12 September 2019 - 04:55 PM

Hello All experts,

 

I wanted to know what are some valid assumptions for temperature of the bulk gas inside the vessel during blowdown or depressurization. Is it anyway safe to assume the temp. of the bulk gas will be constant and would not vary at all during depressurization? Or are there some other assumptions or methodologies that can be used to predict temp. decrease during blowdown as the pressure goes down.

rs



#2 Bobby Strain

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Posted 12 September 2019 - 05:52 PM

It depends.

 

Bobby



#3 PhilippM

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Posted 13 September 2019 - 05:33 AM

You should probably look at section 4.6.3 of API 521 and if I remember correctly Aspen Hysys allows you to create a dynamic simulation of a vessel being depressurized



#4 rs20170808@gmail.com

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Posted 13 September 2019 - 11:31 AM

You should probably look at section 4.6.3 of API 521 and if I remember correctly Aspen Hysys allows you to create a dynamic simulation of a vessel being depressurized

Hi Phillip, for more clarity I am trying to depressurize from operating pressure of the vessel and this is not for fire case. Assuming this do you think the temp. of bulk gas inside the vessel can remain constant during depressurization (let's say for 15 mins)?



#5 rs20170808@gmail.com

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Posted 13 September 2019 - 11:31 AM

It depends.

 

Bobby

On what factors and parameters?



#6 PaoloPemi

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Posted 13 September 2019 - 01:50 PM

as general rule, if you expand a gas, the temperature decreases,

but , in your case, the behaviour will depend from many factors as initial and final conditions, fluid properties, heat exchanged between the wall and the gas (energy balance) etc.

you can find several threads discussing this topic at cheresources, for simulating a tank depressurization there are procedures as direct integration etc.

but, again, as said by Bobby, it depends from your problem.



#7 breizh

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Posted 13 September 2019 - 07:35 PM

Hi ,

You may find ointers reading the document attached .

Another resource is the search engine in this forum , between FAQ and FB

Good luck

Breizh

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