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Hi pmover; thanks for your respond. 1) The recycle line is taken from air cooler outlet so the temperature rise is limited. Still I am not sure what is the minimum recycle for a reciprocating compressor? 2) My question was about operational advantage / disadvantage to have a spill back line (...

Hi; I have a 2-stage (tandem) reciprocating compressor train. Each stage has a recycle valve to control the suction pressure. The compressor capacity is control by: • Speed control (only by the 1st stage suction pressure) • Clearance pocket During the HAZOP of the project, it was requested to...

Many thanks georgeverghese and pmover for your kind response.

Hi georgeverghese; Many thanks for your kind response. Why should it be opened on manual mode not as part of the compressor sequence? About sequence of the train valve closure and recycle valve opening, I agree with you. However, in my compressor logic diagram, first the inlet/outlet valves...

Hi; The capacity of a reciprocating compressor is controlled by "variable speed drive " and "pocket clearance". The compressor train has a recycle valve to control the pressure at the compressor suction scrubber ( transmitter is located at the compressor suction scrubber). This is required to...

dcasto, Thanks. This can be an arranged operation. My question was about failure of one stage of the compressor during running of the train.

thanks georgeverghese

Hi georgeverghese; Thank you so much for your kind reply. So you also believe that an additional recycle line is not necessary.

Hi; I have been requested to consider a minimum recycle line for a variable speed electrical reciprocating compressor train which it should be used to protect the system for the train blocked discharge case. For a centrifugal compressor, it is normal to consider a minimum recycle line but for a...

No. There is no high demister DP at all. This is an extreme case which was defined during HAZOP meeting and I need to define its consequences.

Dear Johnny; Thanks for advice. I consider this one too.

Dear georgeverghese; Yes you are absolutely right about a & b . I did not think in this way thanks for your kind reply. about the time : 20 second is the maximum time to reach from compressor normal discharge pressure to the trip pressure. Minimum time can be about 5 second. 40 second is the...

Thanks Georgeverghese; yes all these trips are available however activation of them takes times and trip sequence till drive stop step takes about 40 second. In normal shutdown sequence the compressor is received recycle gas but as I mentioned before in this case the compressor cannot receive...

The one minute is the time from activation of trip function by LL pressure transmitter (<20sec) till the driver stops as per the trip sequence (40sec) . In normal case the gas is circulated till compressor trip sequence can be completed however in this case as the demister is blocked there is no...

Hi; I am investigating a reciprocating compressor suction blockage case. In case of the suction scrubber demister blockage about 1 minutes takes till the compressor driver stops. So during this one minute, the compressor cannot have any feed gas as the recycle valve is recycling the gas to the...

Thanks Zeusfaver to share your experience.

Hi ; Is it possible that one stage of a two throw , two stage reciprocating compressor run while the other one is stopped? if yes, except the shaft failure , is there any other possible failure cases to have this scenario ?

Dear georgeverghese; There is two coolers to cool-down the temperature so I do not have any issue with the gas recycling.

Dear rotw and georgeverghese OK it seems I need to think differently and resolve my issue in another way . Thank you so much to share your valuable knowledge.

Dear ROTW; please find my query below in red: The map limit is perfectly defined for your curve attached (fixed speed). Yes, the curve limit is defined but the operational limit (Anti-surge and stonewall) was not shown in the curve. I thought at least the anti-surge limit should be defined in...