3 replies to this topic

[Nagarajan K]

Dear All,

 

The CAVERN  crude inlet line is going up the elevation and joining the cavern top . The mass flow meter and other valves are at a lower elevation and then the crude 42 inch inlet line going thru a vertical loop at a higher elevation and then entering the CAVERN from the top (at top Pressure control valve is provided)  and vertically dropping almost 90 meters .

During the crude transfer to CAVERN , observed pressure fluctuations at the upstream of the vertical loop ( varying from 0.1 kg /cm2 to 1.2 kg/cm2) in a cyclical manner .Also observed flow fluctuations as well as piping vibrations when the pressure was dropping.

It appears the liquid freefall of about 70-90 meters creating a venturi effect and dropping the pressure at the vertical loop.

These fluctuations and vibrations would limit the maximum crude intake flowrate substantially .

 

My question is how to avoid the venturi effect in Vertical Pipeline ??

 

One of suggestion i got was,

To have  a vapour balancing line from the top of the vertical loop to CAVERN  vapour line . adjacent to the crude inlet line , vapour balancing line is available with a 16 inch valve .

 

But was apposed as reason,

 

To avoid vacuum and venture effect a vapour balancing  line, as suggested, shall be connected to the crude line just after the pressure holding valve. However, due to risks of drawing air, we do not recommend to connect the line to the vapour line.

 

Regards,
Nagarajan K

[katmar]

I doubt very much that it is caused by a venturi effect. The behavior you describe is often seen in process plants.  It is simply a case of unbalanced static and frictional heads. You need to work from a known pressure point at the end of the line back towards the vertical loop, calculating the frictional and static head losses/gains as you go so that you can calculate what the pressure at the top of the loop would be.

 

It worries me that you speak of "freefall" of 70-90m. There are many ways of piping up a cavern storage system and you should provide a sketch of the unit so that we can understand what you are trying to do, and what the problems could be.

[Nagarajan K]

42" pipeline is dipped pipe...

[breizh]

thanks to provide a sketch to get a proper answer . I'm sure Harvey will help you if you help us.

Breizh