Discussion on shaft displacement in centrifugal compressors.
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Once driving is normal, the thrust points toward the rear, and the shaft displacement indicates a negative value. The thrust of the low-pressure cylinder points toward the turbine side, while the thrust of the high-pressure cylinder points toward the rear end; the shaft displacement is indicated as a positive value. Can someone explain this sentence? How is the positive or negative direction of displacement defined?
The positive or negative value of the displacement is generally defined as negative when moving toward the probe, and positive when moving away from it
I think it’s positive when it’s in the same direction as the axial force, and negative otherwise.
The positive or negative value of the shaft displacement is relative to the main thrust bearing pad. If the displacement sensor is close to the main thrust bearing, it is generally indicated as a positive value; if it is far from the main thrust bearing, it is generally indicated as a negative value!
It mainly depends on the rotor positioning and the zero point of installation for the displacement sensor. As described above, the displacement sensor should be installed at the secondary axis; once the equipment is operating properly, the rotor moves towards the primary axis, and the displacement value should be negative
The closer to this value, the greater it is; it can be used as a benchmark for the displacement at startup
It mainly focuses on confirming the zero point, and checking the data during static debugging
It is primarily based on the axis displacement zero-point probe: values are positive near the probe and negative away from it.