Pressure Reduction in series

[ssr49119]

We are working on a existing crude oil pipeline which has an existing pressure reduction skid & destination is ship. A new tap off from this existing pipeline downstream of the existing pressure reduction skid goes to a storage tank farm. A new PCV is shown on this tap off for controlling the pressure of crude oil going to the inlet of the floating roof storage tanks. Flow rate varies from 3333 barrels/hr to 9375 barrel/hr. Pressure at inlet of existing pressure reduction skid varies from 800 psig to 1400 psig depending on the flow rate. Distance between existing pressure reduction skid and new PCV is around 800 metres. Will this system of having a PCV downstream of existing pressure reduction skid work properly or will the new PCV and existing pressure reduction skid fight with each other? Awaiting your esteemed response to this query.

 

[EmmanuelTop]

I think you need to attach a simplified sketch of this system. It is a bit hard to troubleshoot based on textual description only.

Thank you


Dejan IVANOVIC
Process Engineer, MSChE

 

[LittleInch]

hmmm, 800m is probably enough, but the risk will always be there. It depends to certain extent on the operation. When flowing to the tank farm is this the only flow through the main skid?

If it is then you will need to have a good controls engineer on hand when you commission it. My guess is that you want the secondary PCV skid to act faster than the main one which will then dampen out the variances, but it could be the other way around. These things are really quite difficult to simulate - trial and error on the control loop gain and damping is the only way to fix it.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ssr49119]

Thank you for your responses.

 

[GameJudge]

Unless I'm missing something, I'm not hearing a big problem here. Variable flow, variable inlet pressure, and you've already addressed that once with the variable flow and variable inlet pressure to your main reducing station.