Reasons for sudden shaft displacement in centrifugal compressors
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One of the centrifugal compressors in our factory developed a sudden fault today. Under normal operation, the axial displacement of the engine’s cylinder block shows a value of 6 mil; this morning it suddenly changed from a positive value to a negative value (around zero mil). It was observed that the system’s behavior was vertical in nature, and at the same time, the leakage from the machine seal increased. Upon checking the DCS system, it was found that none of the process parameters had been adjusted at that time, and the steam temperature driving the turbine also remained unchanged. What causes a sudden displacement of the compressor shaft? If the inter-stage gas seal or balance disc gas seal is damaged, there should be no sudden changes. Are there any other reasons? Dear sea friends, if you have any experience, please share your insights or let’s discuss it together.
I took it on myself. Those who are passing by, please give some advice!
Instrument wire is broken! It’s very likely that this is more or less the situation on my end.
To determine whether there might indeed be a change in shaft displacement, has the temperature of the thrust bearings changed?
The reasons may include rotor imbalance, poor coupling alignment, loose equipment foundations, excessive dust in the medium, inappropriate clearance between the sliding bearings and the shaft, and high lubricating oil temperature; it is best to use a vibration analyzer for inspection!
A change in the leakage rate of the mechanical seal indicates that there is indeed a change in shaft displacement! Since the shaft displacement has changed, hasn’t the temperature of the thrust bearing changed? If the process parameters have not changed and the owner has not reported any abnormalities in shaft vibration, then has there been any change in the lubrication condition? Is there any cooling water or something? Has the cooling condition changed? Additionally, the coupling is also something that needs to be checked! If the process permits, it is best to shut down the machine for an inspection
There must be a problem with the sensor or transmitter~~ Have the instrument control team take a look~~
A single change doesn’t make much of a difference. Make a comprehensive judgment by combining this point temperature with the on-site oil pressure. An increase in seal leakage only reflects problems with the seal itself. It is independent of shaft displacement. Support the view that instruments fail!
Only vibration fluctuations have been experienced, with no abnormal displacement. How close is the actual value to the alarm value and the trip value? If you are still in the safe zone, it is recommended to first contact the instrument to check whether there is a fault with it. I don’t think it’s that scary if the displacement is just a bit larger.
The original poster posted a message and then disappeared... The temperature of the thrust bearing should change as the shaft displacement changes; some time ago, when the displacement changed by 0.06 mm, the temperature rose by 6 degrees.
The shaft displacement should be directly related to the temperature of the thrust bearings; it is possible to determine whether there has been a change in shaft displacement by checking the temperature of these bearings!