is dedicated control system required for anti-surge control of compressor? if yes what are the reasons?

 

No it doesn't. Why do you ask.

> is dedicated control system required for anti-surge control of compressor?

 

Yes it does.

 

> Yes it does.

OK.

Why ?!

 

When a compressor goes into a stall state it can happen very quickly. So the controller needs to be able to react to the stall in a very short time. A conventional DCS may have a long scan time - perhaps up to 0.5 s - and may not be able to achieve a fast enough response. Having said that, most modern systems allow you to specify individual scan times for each loop, and in this case there should be no problem. If necessary, dedicate a single controller card or equivalent to the anti-surge function.

 

I would not have a compressor controlled by DCS.

A PLC is capable is acting within 20-30ms - faster if justified within it's design.

 

I think I've seen one of GE's control design specifications recommend 5ms scan rate on compressor pressure for surge sensing, with a fuel valve closing within 200ms. As the others have pointed out, you just don't see that type of scan rates in DCS systems.

-Frank

>> Yes it does.

> OK. Why ?!

 

> No it doesn't. Why do you ask.

>> is dedicated control system required for anti-surge control of compressor?

we have dedicated control system for this of GHH make. in parallel to this, it is also configured on DCS. We can transfer on either in running compressor. our GHH system is old & obsolete. question is should we upgrade it or run on dcs?