5 replies to this topic

[Shamsi]

Hello everyone,

HP Flare seal drum in our refinery is sized for 160000 kg/hr of gas flow. But when the gas flow exceeds 600-700 kg/hr, seal water is blown to the other side of baffle so agressively that we cannot maintain the seal. Our water make-up line have sufficient capacity to tolerate, but we are forced to lower the seal level when there is no water left in water surge drum.

We can maintain the seal when water drain line at the other side of the baffle is blocked. So seal water is not blown towards stack. İt is blown to the other side of the baffle.

I have looked for API 521 and some design guidelines but I couldn't find any criteria for amount of liquid blown off to other side of the baffle to consider. All I found is, there should be sufficient water make-up for losses.

I have summarized some design information below:

Diameter - 3 m
Length - 6 m( 3 meters for sealing area 3 m for other side of baffle)
Inlet pipe submergence height - 1 m
Baffle height - 2m
Inlet pipe diameter - 36"


Appreciate your thoughts about the problem described.

Regards,

[Bobby Strain]

You should provide a sketch of the drum with dimensions. And details.

 

Bobby

[Shamsi]

Thanks for your interest, Mr.Bobby. I have attached detailed drawing of the drum.

Attached Files

•  HP water seal drum drawing.pdf   384.3KB   42 downloads

[Bobby Strain]

It appears that the drum is sloped, lower at the outlet. My experience is with vertical seal drums with inlet via a hood on the perimeter. They had overflow baffle with only a small area allocated to the overflow. And the seal was not so deep. I don't think you can improve the operation until a shutdown when you can alter the design. Whoever designed the drum did a poor job. The flare tip vendors are the best to design the seal drum. You should talk with them.

 

Bobby

[Shamsi]

Thanks, Mr. Bobby for your advice. I will contact with them.

 

Also, I have noticed that configuration of gas inlet and outlet lines of our drum  is different from what is given as a reference sketch in API-521 for horizontal water seal drum(attached). According to API sketch overflow area is located apart from gas flow pathway(on the right side of sketch). But in our case overflow area is located within the pathway of gas flow. I think that maybe there is excessive entrainment of seal water to overflow area because of this faulty design.

 

İn our case, flow path length is higher than API configuration as there is more distance between inlet and outlet lines for same drum size. Maybe design engineer ''optimized'' the drum size by changing inlet and outlet configuration. 

 

It would be perfect to know your opinion about this.

 

Best regards,

 

 

 

 

Attached Files

•  API 521 Typical Horizontal Water Seal Drum Sketch .PNG   78.62KB   5 downloads

Edited by Shamsi, 14 September 2023 - 06:00 AM.

[breizh]

Hi,

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https://www.johnzink...s-applications/

 

Good luck

Breizh