Distance between surge line and discharge NRV

[DiegoMartinez]

People,
Do you know if it is a requirement that the distance between the compressor surge connection take off from the discharge line and the discharge check valve to be minimum? If so, what is the standard?

Regards,
Diego

 

[pmover]

the anti-surge pipe tie-in connection (typically a tee branch connection) should be upstream of discharge check valve. upstream being defined as direction of process fluid flow within the pipe. as far as distance, i am not aware of any "standard". however, think about this, locating an anti-surge tie-in connection further away from the compressor does impact the amount "surge margin" implemented into the controller. some operators or field engineers may slightly increase the surge margin so as to allow for "imperfections" in the anti-surge system operation. mainly due to a time delay between sensing the onset of surge and the subsequent response observed by primary sensor.
each application/installation is unique and requires careful planning and preparation for proper installation and operation of the entire anti-surge system.

hope this helps.

good luck!
-pmover

 

[dcasto]

No standard and as pmover, the shorther the distance the better. I've actually ran a systems where we had an antisurge set with several hundred feet of pipe and a dozen vessels between the discharge and suction of the compresor., but there was a second more sophisticated that would kick in if it detected surge and it rarely if ever operated.

 

[milltir]

You want to minimise the inventory held between 3 points
1. Compressor discharge check valve
2. Anti-surge recycle valve (take-off for this, as pmover said, to be upstream of the discharge check valve)
3. Compressor discharge flange
If this inventory isn't minimised the anti-surge control system won't be able to react quickly enough. Get a dynamic simulation done if you can because the worst case will usually be on a trip.