how to implement surge control in centrifugal compressor 2 stage?
what parameters need to be considered in designing surge control?
anyone has a good experince in CCC surge control can give small breif a bout it ? and how to tune controller for two antisurge control valves?

 

You tune CCC anti-surge controllers just the same way as any other controller. Its best to move the setpoint further from the surge line to give a little extra safety margin i.e. increase b1 and then move RT back where it was. Make sure the recycle valve is working properly i.e. not too much hysteresis etc. I then do an open loop step test and analysis the process response. The PV is 'S' so I generate this by recording the flow, pressures and temperatures and then converting to S in Excel. The equations are given in the CCC manual. I use my u-tune product to calculate the parameters (http://www.contek-systems.co.uk/Products.htm). I find that anti-surge loops tend to give very repeatable results and are therefore simple to tune.

The technique for non-CCC anti-surge controllers is usually just as straightforward. Some are no more than simple flow controllers. Always check that the PID has been implemented correctly. There's at least one vendor out there who's not normalised the controller inputs so the tuning parameters have to be based on engineering units.

For your other questions, I'd refer to the CCC literature. Their anti-surge controller manual gives loads of detail.

Regards
John Greene
http://www.contek-systems.co.uk/index.htm