Hello Dear All,
Do you have this similar experience to the above subjected issue? Thanks.
1. For every time of steam turbne (condensing) startup, the sawtooth type vibration fluctuation will be happening after the speed reaches close to operating speed, and after a certain time ( around 20 minutes) the vibration will be suddenly stable.
2. Based on the trends of steam turbine operating parameters:
- no obvious evidence indicates the vibration is related to hot start or cold start.
- no obvious evidence indicates the vibration is related to delta T between upper casing and lower casing.
- no obvious evidence indicates the vibration is related to exhaust pressure
3. During the vibration fluctuation the vibration phase is varying in a small range,but 1x always is dominant. -----It looks like small rubbing is happening and resulting in thermal unbalance （morton effect).
My question is which will result in this phenomenon and the vibration suddenly becomes stable after around 20 minutes.