LPG Storage Vapor Balance Line

[barqueiroenmarte]

Hello,

I am designing the conceptual engineering of a LPG storage, including six propane spheres of 3500 m3 each apart from other smaller bullets.

I have seen in previous projects (with smaller spheres) that is usual to connect all the vapor spaces of the spheres by means of a balance line. I suppose that whether such line is necessary or not depends on the flow rate when loading and unloading the spheres as well as on the sphere volume. Is it so? In case of big spheres that balance line is still worth? Any criteria about installing that line or not?

Thank you.

 

[dcasto]

If you want to flow similtaneously in/out of more than 1 sphere at a time, a balancing line is highly recommended. Also, If the rates of flowing into even 1 sphere at a time is very high a balancing line will allow vapors to more between tanks and keep either the pump that pumps out of the sphere from cavatating. Or if filling the sphere, from it pressuring it up. From experience, you can move 300 GPM in or out of 90,000 gallons of storage without equalizing. That ratio is then 300 meters storage/1 cubic meter per minute movement.

 

[barqueiroenmarte]

Thank you very much for those numbers. I think that when you say "300 meters storage/1 cubic meter per minute movement", if for example, I have tu pump out 1 m3/min of a 150m3 bullet is just necessary to connect that bullet to any other 150 m3 bullet, so 150 m3+150 m3=300 m3. Is it right?

Regards

 

[dcasto]

yes that is correct. I forgot the meter cubed on the volume, it should be: 300 meters^3 storage / 1 meters^3 per minute