Apr. 04, 2022
The oscillations of turbo-generator sets are directly related to the safe operation of turbo-generator sets, and safety is a great economic benefit for power plants. There are many reasons for excessive oscillation of the unit, including planning and production, operation, installation and maintenance. The following factors are introduced respectively.
Turbogenerator rotor is a high-speed rotating machinery, if the rotor centroid and rotating center do not coincide with the imbalance of the rotor will produce a centrifugal force, the centrifugal force on the bearing produces an exciting force to cause the unit oscillation, if the centrifugal force is too large, the unit oscillation will be abnormal. Therefore, the turbine generator rotor in the installation of each device blade should be the stage of the blade into the action balance test, the whole rotor device completed before leaving the factory should also be the whole rotor low speed and high speed dynamic balance, to ensure that the unbalance of the rotor in a qualified range.
In the manufacturer, the rotor unbalance is mainly caused by mechanical processing accuracy is not enough and poor quality of the device, so it is necessary to improve the processing accuracy, together to ensure the quality of the device, and then to ensure that the original unbalance of the rotor is not too big. In addition, if the planning of the unit is not proper, it will also cause the oscillation of the unit. For example, in the planning stage, the selection of bearings is very important. If bearings are not selected properly, the small unbalance of the rotor may also cause large oscillation of the unit because of poor bearing stability. Perhaps the oil film composition is not good and it is easy to induce oil film oscillation.
Installation and Maintenance
Device and maintenance of unit oscillation is very large, according to the experience of on-site unit oscillation, the on-site oscillation of many units is mostly caused by improper device and maintenance, perhaps the unit oscillation can be solved by device or maintenance in many cases. In view of the field situation, the following points are introduced to several aspects that have a significant impact on unit oscillations.
1. Bearing elevation
Both ends of the turbine or generator rotor are supported by bearings. If the bearing elevation at both ends is not within a reasonable range, the load distribution of the bearings at both ends is unreasonable. Therefore, during the overhaul or installation of the unit, the bearing elevation of the unit should be carefully adjusted according to the recommendations of the manufacturer and combined with the actual situation of each factory. Because the data supplied by the manufacturer is based on the cold state of the unit and then summed up the general unit after heating swell condition, because the actual situation of each unit is not the same, so the swell after heating is not completely the same, so it is necessary to combine the actual situation of each plant to adjust the bearing elevation of the unit.
2. Unit Center
Unit center shall include concentricity of rotor and cylinder or stator, elevation of bearing supporting rotor, concentricity and straightness of shafting connection. If the concentricity deviation between rotor and cylinder or stator is too large, it may cause steam flow excitation, electromagnetic excitation and dynamic collision. If the collision occurs at the rotor shaft, the rotor will be thermally bent and unstable general forced oscillations will be caused.
Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. established in 2006, is an manufacturer of diesel generator in China, which integrates design, supply, commissioning and maintenance of diesel generator set. Product covers Cummins, Perkins, Volvo, Yuchai, Shangchai, Deutz, Ricardo, MTU, Weichai etc. with power range 20kw-3000kw, and become their OEM factory and technology center.
Jun. 24, 2022
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