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Dear Sir,
In our gas booster station, we have a single stage centrifugal compressor to maintain gas pressure at discharge.
At present we are in the stage of commissioning accordingly we started the compressor last day in recirculation mode (compressor ratio about 1.05) and started to increase the compressor ratio up to 1.35 (Trip is set for 1.6). During this operation we kept suction valve and discharge manual ball valve closed and discharge and suction block valves were opened to 25%. We have maintained the suction pressure by opening block valve by-pass line. Our compressor speed is 27000rpm and suction pressure will be about 22 bar and discharge pressure will be about 32 bar. Discharge safety relief valve setting is 36 bar. Motor and impeller are connecting via a gear box to increase the speed.
Initially we set the thrust probe before charge the compressor with gas and once the gas charged the axial position has moved towards motor end (maximum value) about -8mils accordingly we backed the probes to the maximum and started the compressor and noticed the axial movements about 14mils and resetted the probes accordingly. We set the axial thrust movement alarm for +/-11mils and trip for +/-20mils (it has been increased to +/-14mils to +/-20mils to notice the movement).
During this test, we noticed that the axial thrust has kept increased as the compressor ratio increases (+18mils) and we stopped the compressor.
What might be the root cause? Is this normal? Kindly share your experience.
Thank you in advance.
In our gas booster station, we have a single stage centrifugal compressor to maintain gas pressure at discharge.
At present we are in the stage of commissioning accordingly we started the compressor last day in recirculation mode (compressor ratio about 1.05) and started to increase the compressor ratio up to 1.35 (Trip is set for 1.6). During this operation we kept suction valve and discharge manual ball valve closed and discharge and suction block valves were opened to 25%. We have maintained the suction pressure by opening block valve by-pass line. Our compressor speed is 27000rpm and suction pressure will be about 22 bar and discharge pressure will be about 32 bar. Discharge safety relief valve setting is 36 bar. Motor and impeller are connecting via a gear box to increase the speed.
Initially we set the thrust probe before charge the compressor with gas and once the gas charged the axial position has moved towards motor end (maximum value) about -8mils accordingly we backed the probes to the maximum and started the compressor and noticed the axial movements about 14mils and resetted the probes accordingly. We set the axial thrust movement alarm for +/-11mils and trip for +/-20mils (it has been increased to +/-14mils to +/-20mils to notice the movement).
During this test, we noticed that the axial thrust has kept increased as the compressor ratio increases (+18mils) and we stopped the compressor.
What might be the root cause? Is this normal? Kindly share your experience.
Thank you in advance.
