Hi we have 3 stage integrally gear
Hi we have 3 stage integrally gear
(OP)
Hi
we have 3 stage integrally geared compressor.
after unbalance 3th stage it change with new one and 3th bearings change too but it trip after start because of high vibration on 3th stage.
3th stage rpm: 40000 1th and 2th critical speed: 11000 - 34000
bearing: tilting pad with 5 pads. load between pads.
we have 3 stage integrally geared compressor.
after unbalance 3th stage it change with new one and 3th bearings change too but it trip after start because of high vibration on 3th stage.
3th stage rpm: 40000 1th and 2th critical speed: 11000 - 34000
bearing: tilting pad with 5 pads. load between pads.
RE: Hi we have 3 stage integrally gear
It seems to me that you should have replaced the complete set of stages/bearings not only the 3rd stage. Because if the flow condition is offset (due to gas dirtiness / deposit or/and wear and tear etc.) the 3rd stage will be operating the most off design due to flow "stacking" effect across the impeller stages (especially if you do not have IGV's or some other process control method to correct/mitigate that effect). So now that you have set back the 3rd stage to its original design parameters by replacing your3rd stage set [bearing + rotor] you are still standing at same place as far as wear & tear, performance degradation, and even unbalance, of 1st and 2nd stage are concerned.
Going even further in the speculation, the behavior of high vibration trip could also possibly mean that the unbalance that occurred at first place has part of its root cause mostly in 1st / 2nd stage systems.
With such poor info and description - this is again just speculation.
RE: Hi we have 3 stage integrally gear
thanks rotw
actually machine tripped because of 3rd stage vibration and we just replace impeller and bearing of it.
after dismantle the machine we observed 3rd stage impeller in bad shape because of excessive wear. but 1rd and 2rd stage had no problem.
we knew most of failure causes refer to 3rd (high speed) stage experimentally but we have no idea for after maintenance trips.
its even condition monitoring couldn't help us because of unusual trend.
RE: Hi we have 3 stage integrally gear
Johnny Pellin
RE: Hi we have 3 stage integrally gear
probes area was a good point.
its bearings are 5 shoes tiiting pad and its not show 1x and 90 degree phase (or 30 less or more).
as i knew shaft unbalance observed on previous condition. may it different with different bearing type? tilting pad, 3 lobe, lemon type and etc.