4 replies to this topic

[pklavins]

I'm currently reviewing some previous designs of an as-built compressor station and noticed some inconsistencies regarding the ESDVs:

• Two compressors have no ESDVs on the inlet or the discharge
• Two compressors have an inlet ESDV and a discharge ESDV

All of the compressors are multi-stage centrifugals. Is there a standard to follow and what are the reasons for having one on the inlet and outlet? My hunch would be to isolate the equipment in case of a fire, but I'm not sure.  

 

Any advice or comments are appreciated.Thank you.

[Bobby Strain]

You are correct. Just omit "in case of fire" from your hunch. If you study your logic diagrams for the compressors with ESDs you can see what activates them. Certainly when the compressor stops, the valves should close.

 

Bobby

[pklavins]

Thanks Bobby. I further discussed it with a couple of co-workers and the primary reason was that during shutdown the blowdown valves open as well. The blowdown valves have been sized to depressurize the compressor only in 15 minutes to 100 psig (not the compressor and all of the inlet piping). Having the ESDVs on the inlet and discharge to isolate during shutdown/blowdown seems logical. Thank you.

[fallah]

pklavins,

 

After compressor shut down two SDVs in suction and discharge lines are to be closed and the compressor will go to settle out conditions. Then, depending on the case and situation it may be depressurized through a BDV (emergency shut down due to a fire case) or may not be depressurized (normal shut down)...

[trinhduchanh]

pklavins,

 

Normally centifugal compressor will have two situation for shutdown.

• Ventilated shutdown: all SDV for suction and discharge should be Close, Antisure Valve will Open and each BDV at every stage will be Open for blowdown pressure inside casing.
• Pressurised shutdown: Valve Open/Close sequence will be same with Ventilated shutdown but BDV will Close when casing pressure reach 4.5 barg. During this shutdown, BDV will Open and Close for control casing pressure at 4.5 Barg.