Centrifugal compressor: When operating at full load, if the anti-surge valve opens suddenly and the speed cannot be reduced fast enough, what damage can this cause to the unit?
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The centrifugal compressor of the unit has a remote fault; currently, a synchronizer is being used to increase the speed and maintain operation. Question: During normal operation, if the anti-surge valve suddenly opens, and the speed is being controlled by a synchronizer, it is not possible to reduce the speed promptly. May I ask: What harm does running in this way cause to the unit? Thank you first!
In other words, the excitation cannot be automatically controlled?
It’s not excitation; it’s the centrifugal compressor suddenly losing load, and its speed cannot be reduced when a speed setpoint is specified (in manual mode).
Damage to the unit can occur; damage to the bearing shells or problems with the rotor oil seals can all lead to the unit needing to be scrapped
The compressor has an overspeed protection, right? The first bearing will be damaged due to excessive rotational speed, which leads to an increase in temperature and a reduction in the thickness of the oil film; as a result, the bearing is damaged, and the shaft is also damaged.
Why does this happen (just a sudden load rejection, with the oil system functioning properly, and mechanical and electronic overspeed protections in place)? Could you explain the reasons in detail?
Our system is independent and uses floating ring sealing. The unit is equipped with electronic and mechanical overspeed protection; in the event of a sudden load loss, I believe it would cause an overspeed shutdown. Since lubrication is not interrupted, the damage to the bearings should not be that severe.
Our system is independent and uses floating ring sealing. The unit is equipped with electronic and mechanical overspeed protection; in the event of a sudden load loss, I believe it would cause an overspeed shutdown. Since lubrication is not interrupted, the damage to the bearings should not be that severe.
As long as there is protection, there’s no need to worry; generally, a speed excess of 10% has no impact on the engine unit.
Firstly, I believe that suddenly releasing the load without reducing the speed does no harm to the compressor itself. However, it is necessary to analyze the reason why the anti-surge valve opened fully suddenly; it may be that the surge protection was triggered. Operation at a constant speed, especially at high speeds, brings the compressor’s operating point close to the surge control line; fluctuations in flow rate can cause the compressor to surge, thereby causing damage to the unit. Suggestions: 1. Fix the remote transmission issue as soon as possible ； 2. The compressor is currently in manual mode; it is recommended to reduce the speed and increase the opening degree of the anti-surge valve, so that the compressor’s operating point remains within the safe range. Also, what process is your compressor used in?
Surge is generally caused by high pressure and low pressure, as well as an insufficient rotation speed; increasing the rotation speed can prevent surge.