3 replies to this topic

[vvsastry66]

Dear Respected Members,

 

We are proposing a new flare gas recovery compressor, a reciprocatin machine, due to low flow/high pressure, 1500 kg/hr and 30 barg discharge pressure. The compressor system (intercoolers/drums) suck flare gas (otherwise routed to flare) from a pressure of 0.1 barg and compress to 30 barg, and discharge gas/condensed liquids recycled to upstream process. Our client is insisting on:

 

A pressure control valve on suction of compressor, which will throttle suction flow. If suction pressure is high, even after compressor is at full speed, flare valve will open, otherwise suction flow is throttled.   Additionally there are valve unloaders, variable speed control and recycle valve also. 

 

What we have provided is a recycle valve, which on low suction pressure will recycle discharge gas. And on high suction pressure, flare valve will open.

 

We told them, if suction valve is controlled, compressor may starve and create vacuum. 

 

Could you people tell me if suction valve control method is correct. 

 

Thank you

Sastry

[Bobby Strain]

I wouldn't use it. Potential of air ingress in the event of vacuum. I would use less risky methods. The client pays the bills, so you need to pay attention to her. To avoid future liability from an explosion, get all instructions in writing. Make sure the person who directs you is really the client or just a hired hand.

 

Bobby

[Zubair Exclaim]

well i have seen this suction valve control on gas compression units, but those suction pressures are high in excess of 300 psig .... in case of such low pressures you need to explain it to him the potential hazards involved.

 

if you have high and low pressure shut downs on the compresor thing should work fine without suction control valve

[vvsastry66]

may be suction valves are for centrifugal machines. Otherwise compressor starves.