Surges occur when the compressor outlet pressure is too high in relation to the flow through the compressor. The flow can change rapidly when there is a sudden change in the load that the compressor is expected to deliver. If the surge is not controlled, the compressor can be destroyed. An anti-surge control strategy is designed to protecta compressor from these surges.

The typical methods for accomplishing surge control are either a blow-off to atmosphere or recirculation from the outlet to the inlet of the compressor. The anti-surge control strategy is tightly integrated with the compressor load control strategy.

sir, would you like to explain me what kind control valve use for this & also other sensors....like pressure tx,flow tx

The two critical components of a surge control loop are the flow sensor and the surge valve. Both must be fast, accurate, and reliable.

Antisurge control usually requires a flow sensor on the suction side of the compressor.

Surge Control Valves

Surge valves are usually fail-open,linear valves that are tuned for fast and precise throttling.

Because the valve is the weak link in the total surge protection system, and because testing and maintenance cannot be done on-line if only one valve is used, total redundancy is recommended. Each of the two parallel surge valves should be sized for the full flow of the compressor but for only 70% of thedischarge pressure. This pressure reduction is caused by the flow reversals during surge.

YOu can plot the surge curve based on power , flow with discharge pressure.

you will require Pressure transmitters, power transducers and flow transmitters which also can be a DP transmitter, Rosemount provides very good range, reliablity and resolution.

surge valves have to be quick actung and need to open full in less than 2s if there is a surge detection.,

It is advised to plot the surge curve and increase or elevate the line by x% on the upside in order to prevent the machine, in this case if surge detected open the valve X % above 50% that is.