Dynamic balance of compressor rotor

Impure compressed gas can form scale layers that adhere to the surface of the impeller, which in turn disrupts the dynamic balance of the rotor and leads to excessive shaft vibration

1. Rotor corrosion, resulting in dynamic imbalance. 2. Adhesion of viscous substances to the rotor, causing dynamic imbalance. 3. Water present in the oil, along with uneven vaporization of oil and water, leading to vibrations. 4. A large gap between the shaft and the bearing shells can also cause dynamic imbalance. 5. Excessively high or low oil pressure can also have an impact. 6. Are there any loose components among the other auxiliary parts?

A dynamic balance check of the rotor should be considered when any of the following situations occurs. ①The vibration amplitude increases during motion, especially in those cases where a large amount of high-frequency components is detected in the spectral analysis. ②The vibration amplitude increases during operation, the cause of the vibration is unknown, or the amplitude keeps increasing with rotational speed. ③The rotor shaft bends, and the end-face runout of the impeller as well as the radial runout of the main shaft increase, especially when there are significant changes in the direction and amplitude of the runouts in various areas. ④The impeller suffers uneven wear and corrosion in the circumferential direction, with local material loss. ⑤When the amplitude value increases significantly at the critical speed, with no other explainable reasons.

The principles of dynamic balancing are as follows: ① The rotor can achieve mass balance either through low-speed dynamic balancing or through high-speed dynamic balancing. High-speed dynamic balancing should be considered for high-speed, light-load rotors, or those that still exhibit significant vibration at operating speeds despite having undergone low-speed dynamic balancing; for rotors whose main rotating components such as impellers and balance discs have been replaced; and for rotors whose maximum runout does not occur in the same direction within the same axial cross-section. ②The dynamic balancing unweighting position, grinding depth, and surface roughness shall meet the manufacturer’s design requirements; all ground surfaces must be smooth and have a seamless transition, and shall be polished with metallographic sandpaper. When grinding, pay attention to controlling the grinding feed rate and the wheel speed to prevent the material from overheating. ③Removable rotating components such as couplings (when replacing these parts) should be individually balanced in advance. Only when all these components are proven to be balanced can they be assembled for overall dynamic balancing. When performing overall balancing, adjustments must not be made to components that have already been balanced. After balancing, there should be alignment marks between the rotating component and the shaft. Low-speed dynamic balancing can be determined based on the capabilities of the balancing manufacturer and the dynamic balancing machine, but the balancing accuracy must reach ISO 1.0 level. High-speed dynamic balancing should ensure that, at the normal operating speed, the vibration amplitude of the rotor on the balance machine’s support does not exceed 1 g.mm/s, and that there are no fluctuations in amplitude or phase within the range up to the maximum continuous speed.

Thanks for sharing:victory:

Thanks for sharing! :handshake

Factors affecting rotor imbalance: 1. Rotor corrosion, which causes dynamic imbalance. 2. Adhesion of viscous substances to the rotor, leading to dynamic imbalance. 3. Water in the oil composition, as well as uneven vaporization of oil and water, can cause vibrations. 4. A large gap between the shaft and the bearing shells can also result in dynamic imbalance. 5. Excessively high or low oil pressure can also have an impact. 6. Whether there is any looseness in other attached components. In any of the above situations, it is necessary to consider performing a dynamic balance check on the rotor. ①The vibration amplitude increases during motion, especially in those cases where a large amount of high-frequency components is detected in the spectral analysis. ②The vibration amplitude increases during operation, the cause of the vibration is unknown, or the amplitude keeps increasing with rotational speed. ③The rotor shaft bends, and the end-face runout of the impeller as well as the radial runout of the main shaft increase, especially when there are significant changes in the direction and amplitude of the runouts in various areas. ④The impeller suffers uneven wear and corrosion in the circumferential direction, with local material loss. ⑤When the amplitude value increases significantly at the critical speed, with no other explainable reasons. The principles of rotor dynamic balancing are as follows: ① The rotor can achieve mass balance either through low-speed dynamic balancing or through high-speed dynamic balancing. High-speed dynamic balancing should be considered for high-speed, light-load rotors, or those that still exhibit significant vibration at operating speeds despite having undergone low-speed dynamic balancing; for rotors whose main rotating components such as impellers and balance discs have been replaced; and for rotors whose maximum runout does not occur in the same direction within the same axial cross-section. ②The dynamic balancing unweighting position, grinding depth, and surface roughness shall meet the manufacturer’s design requirements; all ground surfaces must be smooth and have a seamless transition, and shall be polished with metallographic sandpaper. When grinding, pay attention to controlling the grinding feed rate and the wheel speed to prevent the material from overheating. ③Removable rotating components such as couplings (when replacing these parts) should be individually balanced in advance. Only when all these components are proven to be balanced can they be assembled for overall dynamic balancing. When performing overall balancing, adjustments must not be made to components that have already been balanced. After balancing, there should be alignment marks between the rotating component and the shaft. Low-speed dynamic balancing can be determined based on the capabilities of the balancing manufacturer and the dynamic balancing machine, but the balancing accuracy must reach ISO 1.0 level. High-speed dynamic balancing should ensure that, at the normal operating speed, the vibration amplitude of the rotor on the balance machine’s support does not exceed 1 g.mm/s, and that there are no fluctuations in amplitude or phase within the range up to the maximum continuous speed.

Thank you! :handshake :victory:

First, perform the dynamic balancing of individual components, and then carry out the overall dynamic balancing; neither step can be omitted.

Precautions for balancing the centrifuge rotor of the H905 compressor: Sometimes, the balancing process does not yield obvious results; in such cases, it is necessary to contact the manufacturer to conduct an electronic runout inspection of the shaft journals. These inspections must meet the factory’s standards in order to eliminate the influence of surface magnetism and surface finish on vibration levels – information that is not provided in the manual.

I happened to pass by, but I agree with what was said above