Three-stage vibration problem of centrifugal air compressor
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Please tell me, there is a problem of high vibration in the third stage (final stage) of the centrifugal air compressor in our workshop. In the picture, the red color is the third-stage vibration trend chart, the yellow color is the air compressor outlet pressure trend chart, and the white color is the third-stage (final stage) temperature trend chart. Please tell me the cause of the vibration. There was a time when the compressor was in the forced unloading state during startup, but before it was loaded, a three-level high vibration alarm occurred and an interlocking shutdown occurred. After inspection, no problems with the instrumentation and equipment were found (the machine was disassembled and the final stage was cleaned). The equipment supervisor said it was caused by equipment surge. I would like to ask, will surge occur when the compressor is not loaded?
It should be that the back-end air consumption is unstable. Normally, the exhaust pressure of the centrifugal air compressor is very stable, unless the back-end air consumption increases or suddenly decreases, causing the system to think that the back-end is unstable.
“Will surge occur when the compressor is not loaded? ”. This phenomenon exists. For example, the preparation work before starting requires that the suction valve must have a certain suction volume, and the opening of the valve (guide vane) must be set according to the instructions. However, when using it, the error is usually too large and the inhalation volume is too small. It will cause periodic vibrations. Of course, this surge sound is much smaller than the surge sound caused by the increase in pressure behind the machine. Judging from the trend yellow line, the fluctuation time is too long and does not look like a surge. It is recommended that if the cranking is normal and there is no water in the gas phase of the cooler, it can be started again, and the minimum current after startup and the vibration sound in the equipment can be strictly monitored to judge. As long as the equipment is not mechanical, it will not be damaged. Increase the inhalation volume appropriately. Reduce troubleshooting possibilities. For reference.
Tips from the Design Institute: No load is added, if it means the outlet is vented. Let me tell you clearly that export shorting will not cause surge.