Anti surge line of Compressor 1

[MT47]

Hi-everybody Please to answer me :Anti surge line should be considered for centrifugal compressor or not?If the anti surge line didn't considere ,what is recomendation for preventing from surge.
Thank you.

 

[JimCasey]

Yes. antisurge line should be a part of centrifugal compressor installation. AND you should have a dedicated antisurge system. The larger the compressor the more important an antisurge system is. One company that knows what they are doing is Compressor Controls Corp. (

http://www.cccglobal.com/products.asp)

 

[vzeos]

I agree with JimCasey. In addition, I think some manufacturers offer surge trip switches that would shut the unit down during a surge event. The trip switches are not a replacement for the surge control system but would serve as a backup to prevent damage to your compressor and piping.

Another company that can provide a surge control system is Petrotech, inc.

http://www.petrotechinc.com/

 

[liberoSimulation]

I had a situation where a technology provider of a petrochemical plant had provided two anti-surge (or kick-back) lines for a 5 stage centrifugal compressor (driven by 60 MW steam turbine) and when the compressor vendor had got this inquiry for the compressor with these two lines; the Vendor said the more anti-surge line installed the better protection of for the individual stages from surge conditions but the more energy consumption is increased.
I think the less anti-surge lines, the bigger size of anti-surge lines are required as to provide flow back to the protected stages. Big size leads large pressure drop and special valves to be evaluated in the market.
Other need of anti-surge is for start-up where the kick-backs are open as the plant throughput (or load) has to be brought up gradually. Also, if plant load is reduced (turndown case) kick-backs usually are open to maintain a safe margin from surge of the stage.

Hope this would give an explanation to your question.

Regards to all

 

[Longinthetooth]

As everyone has said, antisurge lines are a must. With the advent of computers, the art has gone way beyond having one simple anti surge line for a multi stage compressor. Remember, it's each individual wheel that surges, not the whole compressor. It is not uncommon now, to have an antisurge on each stage, controlled by a computer that continuously plots the compressor curve as the speed, pressure and flows vary, then adjusts the antisurge to the optimum ammount. As Jim Casey says, CCC does a good one.

 

[MT47]

I am thankful from every one to response me .I found the following point in IPS-750(Iranian petrochemical standard)that it seems anti-surge line isn't necessary always according to API617 .what do you think about this point?

******6.1.3.3 The head-capacity characteristic curve shall rise continuously from the rated point to the predicted surge. The compressor, without the use of a bypass, shall be suitable for continuous operation at any capacity at least 10 percent greater than the predicted approximate surge capacity shown in the proposal (API Std. 617, 2.1.3).******

 

[MortenA]

Surge is phenomena that occurs at low flow/high head. So this sound a little strange in connection with "at leat 10% greater..."?

Anyway: If a centrifugal centrifuge surge it may very well destroy it - so you better be very certain that a surge could never occur (not even during start up/shut down!!!) Ok during the two last occation you may have a manua by-pass line - but still!

Best regards

Morten

 

[jsummerfield]

Think air. No recycle valve is required in air but you still require an anti-surge valve even if vented to the atmosphere.

Anti-surge lines are required in hydrocarbon service. A few other surge control companies inlcude shutdown system outfits like ICS Triplex and Invensys Triconex.

Screw and recip compressors are very diffent than centrifugal.


John

 

[cryotechnic]

I think, every large centrifugal compressor manufacturer will or can supply a anti-surge control system.

In our company, where we have some large compressors, the surgelines, surgelimits are allways determined by the manufacturer. All the other maintenance we are doing ourself, but the surgelimit is so important that after every overhaul, the manufacturer will determine this.

We have one axial-radial compressor. An axial compressor is very sensitive for surging. So we not only have a anti-surge controller, but also a surge-counter which switches off the compressor. Also our multi-stage oxygen-compressors have a surge-counter who switches off the compressor. The temperatures of the pump medium will rise rapidly during surging, which can cause some terrible damage.

So, contact your compressor rep for advice on your surge-controllers.

ABB's Protonic controller is well known as anti-surge controller.
Also CCC is a good one.

By the way, an anti-surge controller is so important, it's not integrated in the DCS/scada control system, but allways as an separate device.

Cryotechnic

 

[reena1957]

Dear MT47,
You have not given the service- Air or hydrocarbon or NH3?
In case of Air, you may have a Snort line line to atmosphere from discharge which serves as an antisurge line. Also is it multi stage, multisuction? Is there a suction to discharge line somewhere? Or the dicharge line connected to a low pressure vessel? Or a safety valve? Pl give some more details. As everybody has pointed out,the manufacturer will specify the requirements & not the buyer. It might be having a different name in your case may be?

 

[MT47]

Thank you from every one to replay me.My case is as follow:

***The single stage compressor is used for providing of fluidisation gas,and the service fluid is hydrocarbon(Ethylene40%,Ethane6.%,Butene 17%, hydrogen 7%, Nitrogen30%)and normal Flowrate is 25700 m3/hr and DP is 2.2 bar.
There are one guide vane valve and stainer in suction line as other compressors and There are TT,PT and flow meter in discharge line but control system has not considered.There are two vertical gas coolers in suction and discharge of the compressor and PSV has considered in the coolers for protection .***

Best regard

 

[reena1957]

Dear MT47,
Are there any block or control valves in the circuit other than compressor isolation valves? I have seen in case of a reformer recycle gas compressor no antisurge protection line as there were no blocks or c/v's in the circuit and flow was controlled by compressor drive speed.

 

[jsummerfield]

You should also look for articles regarding the location of the check valve in relation to the surge valve.

The big compressor packages may buy out the surge controls too. I have worked with some large GE LM2500 gas turbines packaged with GE PLCs and smalle Nuovo Pignone compressors running Petrotech surge controls in a "C++" block loaded in the PLC. On the other hand, Solar packaged surge in their Allen-Bradley PLCs for smaller gas turbine compressors.



John

 

[MT47]

Dear Reena1957
Thank you for reply.There aren't any block valves and control valve and other isolation valves for compressor .
The fluidisation gas are circulated same as reformer recycle gas and in these cases, Anti-surge line isn't necessary.
Best regards