【Weekly Question】Discussion on Increased Shaft Vibration in Centrifugal Compressors
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During the operation of the centrifugal compressor, the vibration of the second-stage shaft among the vibrations of the first, second, and third stages increased gradually from 6.2 μm to 11.5 μm, while those of the first and third stages remained at 5.2 μm (values below 30 μm are considered normal). Let’s discuss what the various factors are that cause vibration in the secondary shaft
The reasons for the increased vibration of the secondary shaft in a centrifugal compressor may include: 1. Bearing damage: The secondary bearings may become worn or damaged, resulting in an increased bearing clearance and thus heightened shaft vibration. 2. Imbalance of the shafting: If the compressor rotor is unbalanced, it will cause additional vibration during operation. The secondary rotor may have an imbalance issue. 3. Shaft bending: Prolonged operation may cause bending at the shaft axis, affecting the rotational balance of the rotor. 4. Lubricant issues: Insufficient oil supply in the lubrication system or problems with the quality of the lubricant can also lead to accelerated wear of the bearings, causing vibration problems. 5. Mechanical looseness: The secondary connection components may be loose, such as loose screws or improper coupling installation, all of which can lead to increased vibration. 6. Variation in operating load: If the operating load of the compressor changes, it may also affect the vibration condition. To address the above possible causes, corresponding inspections and maintenance should be carried out to reduce vibration and ensure the proper operation of the compressor. .
If it’s within a reasonable range, then we can worry about it once it breaks! Mechanically, there is bearing wear, impeller wear, and alignment issues. In terms of the process, the air flow is uneven. There is structural damage; I don’t know how to control the power supply. In theory, there should be a repair manual that can be consulted! Otherwise, check it during maintenance
There are too many reasons; it’s better to collect data online and perform a spectrum analysis to identify the cause, in order to prepare for shutdown and maintenance
To analyze such problems, it is first necessary to determine whether the vibration phenomenon stems from an issue in the initial installation or has developed over time. If the original issue is related to installation, the problems should be sought in aspects such as the levelness of the rotor, coupling alignment, and bearing clearance. If vibration appears gradually over the next few days, it may be due to imbalance in dynamic balance caused by scale buildup on the impeller; in such cases, the impeller should be disassembled to remove the scale. It is also possible that wear in the bearings could lead to excessive clearance, inadequate levelness, and alignment issues. If the current condition is within the acceptable range of vibration, it can continue to be used; if it cannot be maintained, issues should be addressed as soon as possible to avoid more serious problems. Additionally, it is also necessary to check whether there are any issues with the connection between the foundation and the equipment, as well as with the secondary grouting. For reference.