Sequence of opening of anti-surge valves

[EEL23]

I need to know about what should be the sequence of opening of anit-surge valves, when unloading the centrifugal compressor have multiple casing with intercooler and K.O. drums.

 

[atayto]

Could you please give more details about that. I beleive compressor should have only one antisurge valve

 

[EEL23]

Thanks for your interest. We have a synthesis gas compressor which has three casings i.e. LPC (low pressure casing), IPC (intermediate pressure casing) and HPC (high pressure casing). LPC casing has 8 impellers/stages and then gas from LPC goes to cooler and then to K.O. drum, it enters into IPC, it also has 8 stages. From IPC, the gas after passing through cooler, high pressure chiller and K.O. drum enters into HPC. HPC has 7 stages. At 6th stage of HPC, make up gas and recycle gas from synthesis loop mix.

We have three antisurge valves;
1. At the suction of IPC.
2. At the suction of HPC.
3. At the suction of recycle gas from synthesis loop(6th stage of HPC).

 

[atayto]

Dont know about your particular case but usualy every antisurge valve would look after its compressor. IPC antisurge would control IPC compressor, LPC antisurge would control LPC compressor, and HPC antisurge would control HPC compressor. About loading i think LPC will be loading first for this reason its antisurge valve will be partially closed and will reach the point when stable flow and aceptable differential pressure is achieved and then next stage will be loading in the same maner. This is normal way to load staged compressors.Are all three stages located on one shaft or they are three different compressors?