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Liquid Seal Drum Design

liquid seal drum design ground flare

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#1 maginaga

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Posted 12 October 2023 - 07:03 AM

Dear

I'm busy now with designing a vertical liquid seal for a ground flare system.

Acc. to API521 the following can be calculated:

1. Vessel diameter

2. height for vapor space

3. height for leg submersion

However, it is not clear to me what should be the liquid total level or the liquid level under the leg.

 

I would appreciate your help.

 

Best

Magi



#2 Bobby Strain

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Posted 12 October 2023 - 11:26 AM

You should ask your flare vendor to design the seal pot. It requires a special inlet distributor to reduce surges.

 

Bobby



#3 breizh

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Posted 12 October 2023 - 06:29 PM

Hi,

Check your messenger, I've posted a document.

Bobby's advice is great, John Zink company could be contacted thru its website.

Breizh



#4 shvet1

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Posted 13 October 2023 - 12:59 AM

It depends on distributor design. Consult a vendor.

 

image.png



#5 maginaga

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Posted 13 October 2023 - 05:26 AM

Thank you all for the valuable information.
 
First of all, I will introduce myself. My name is Magi Nagar. I have a PhD in chemistry (specialization in electrochemistry) and now I am facing a new challenge as a chemical process engineer. Hence, I have scientific knowledge however, I am new to the refinery industry.
I would like to better understand the logic behind the various parameters so that I can better design a liquid vessel myself.
 
For example: I would assume that the depth of the water below the end of the inlet line is a crucial parameter and depends on the maximum pressure in the inlet pipe. I mean, I don't want gas bubbles hitting the bottom of my vessel and creating waves and splashes.
 
However, in API521, this parameter is not discussed and from your feedback it should be 0.3m or 0.25 of the inlet diameter (whichever is greater) regardless of gas pressure and velocity.
0.3 m of water corresponds to 3KPa...but what if my gauge pressure is higher? Am I not risking splashing and surging?
 
I thought of using Bernoulli's equation because the gas entering the liquid actually has static and dynamic pressure (derived from its pressure, kinetic energy, and gravitational potential energy).
So my thought was first to calculate the pressure at the end of the inlet pipe according to Bernoulli's equation and from there to derive the water height (below the end of inlet pipe) that would correspond to this pressure.
Does that make sense?
I have more questions but first I will thoroughly go over the information you provided.
 
Thanks again
Magi


#6 shvet1

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Posted 13 October 2023 - 05:34 AM

Does that make sense?

 

Negative.

Industrial engineering does not work such way. "Why and how" are not obvious, speculations are dangerous and in cases like this one is are payed by someone's blood. Piloting, extensive tests, practice, experience, positive reports, industry consensus, entity's reputation and responsibility for results.

 

https://youtu.be/e0J...cEufQaHzaRkURGG


Edited by shvet1, 13 October 2023 - 05:50 AM.


#7 maginaga

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Posted 13 October 2023 - 08:00 AM

 

 

Negative.

Industrial engineering does not work such way. "Why and how" are not obvious, speculations are dangerous and in cases like this one is are payed by someone's blood. Piloting, extensive tests, practice, experience, positive reports, industry consensus, entity's reputation and responsibility for results.

 

https://youtu.be/e0J...cEufQaHzaRkURGG

 

I completely agree with you and this is why I'm asking to better understand the liquid height below the end inlet pipe.

As mentioned previously: I would assume that the depth of the water below the end of the inlet line is a crucial parameter and depends on the maximum pressure in the inlet pipe. I mean, I don't want gas bubbles hitting the bottom of my vessel and creating waves and splashes.

 
However, in API521, this parameter is not discussed and from your feedback it should be 0.3m or 0.25 of the inlet diameter (whichever is greater) regardless of gas pressure and velocity.
0.3 m of water corresponds to 3KPa...but what if my gauge pressure is higher? Am I not risking splashing and surging?
 
I would appreciate your insight on that
Best
Magi


#8 shvet1

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Posted 13 October 2023 - 09:32 AM

I would assume that the depth of the water below the end of the inlet line ... depends on the maximum pressure velocity head n the inlet pipe.

 

I mean, I don't want gas bubbles hitting the bottom of my vessel and creating waves and splashes.

It is determined by distributor ID and design, not liquid level.

 

However, in API521, this parameter is not discussed and from your breizh's feedback it should be ...

 

it should be 0.3m or 0.25 of the inlet diameter (whichever is greater) regardless of gas pressure and velocity.

Positive, as it is determined by distributor ID and design.

 

0.3 m of water corresponds to 3KPa...but what if my gauge pressure is higher?

Relief will go to flare

 

Am I not risking splashing and surging?

I do not understand. 

 

What do you think seal is intended for? How does it work during stand-by and relief?


Edited by shvet1, 13 October 2023 - 09:34 AM.


#9 Bobby Strain

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Posted 13 October 2023 - 09:43 AM

This sounds like an academic exercise, not design of a real seal. No matter what you learn, have the flare vendor design the seal. If your company lets you design a real one, shame on them. I'm sure you are an excellent chemist. With enough knowledge not to attempt chemical engineering.

 

Bobby



#10 maginaga

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Posted 16 October 2023 - 02:12 AM

Thank You all.
I thought to use this platform to gain knowledge thus, I appreciate your feedback.
As mentioned, "I completely agree with you" safety comes first. no one will let me to design one and i will not take this responsibility if i do not understand what i'm doing.
Again,  I thought to use this platform to gain knowledge and better understand.
 
Thanks again and good day





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