With the construction of a large number of large-capacity thermal power units put into operation, Axial Fan the axial fan with its flow, Axial Fan start torque is small, Axial Fan the advantages of adaptability to the wind system changes gradually replace the centrifugal fan mainstream. Axial fans have two kinds of adjustment methods: moving leaves and stationary leaves. Adjustable axial flow fan by changing the angle of work leaves to change the working conditions, Axial Fan there is no closure loss, high efficiency, but also to avoid instability in the small flow conditions, but its complex structure, the stability of the regulator and Reliability requirements are higher, Axial Fan the manufacturing accuracy requirements are higher, prone to failure, it is generally only used for blowers and a fan. The adjustable axial fan is changed by changing the flow area and the inlet airflow to change the working conditions. It has the advantages of simple structure and low regulation mechanism. Therefore, Axial Fan it is generally used for the induced draft fan with poor working environment.
With the extensive application of axial fans, and its structural characteristics corresponding to the vibration problem is gradually exposed, these problems in the centrifugal fan is not present or not common. In this paper, Axial Fan we summarize the cases of abnormal vibration faults of various axial fans,Axial Fan and summarize some of the vibrations and their causes.
Adjustable fan-flow fan through the line to adjust the opening degree of the fan to change the operating conditions, which rely mainly on the wheel of the hydraulic control mechanism to achieve the adjustment of the various blade angle involves a series of adjustment components, Parts of the installation, Axial Fan with the parts of the deformation of their own, high wear requirements, hydraulic leaf adjustment system structure shown in Figure 1. The influence of the structure of the blade on the vibration is mainly that the partial leaf opening of the single stage impeller is not synchronized, the blade opening degree of the two impeller is not synchronized and the eccentricity of the regulating part itself is three.
Single-stage impeller part of the blade opening is not synchronized due to the slider wear, Axial Fan adjust the rod and crank with loose, petiole-oriented bearings and thrust bearings caused by poor rotation. These parts are hydraulic cylinder to the moving parts between the moving parts, Axial Fan will lead to part of the fan blade opening is not in place, and the fan blade weight and installation radius are larger, part of the fan blade opening inconsistency will produce serious quality imbalance, Resulting in significant vibration of the fan at high speeds.
1) vibration spectrum and general quality are unbalanced, vibration fault spectrum is mainly frequency components, while some of the leaves will not produce a certain degree of air flow pulsation, Axial Fan so that the vibration spectrum of the blade through the frequency and its harmonics, Axial Fan part of the wear and tear And loose will produce a certain degree of non-linear impact, so that the frequency spectrum of high frequency harmonic components, which in the vibration frequency spectrum performance was relatively obvious in the displacement spectrum is almost impossible to observe.
2) The fan amplitude is unstable, Axial Fan the amplitude change mainly occurs in the process of adjusting the opening of the leaf, the stability of the blade when the stability of the basic stability, Axial Fan and sometimes with the leaf opening changes and gradually change.
3) just to speed to the working speed, Axial Fan fan blades are not open or open smaller, the fan amplitude is generally small.
The eccentricity of the regulating parts mainly refers to the installation of eccentric and loose parts of the larger adjustment parts. Axial Fan Due to the large quality, when the rotation center and the center of the rotor are deflected, a large mass imbalance will occur and the eccentricity caused by loosening Will also produce quality imbalance. For the adjustable axial fan, the main design of the hydraulic cylinder eccentric and loose. Axial Fan If only the hydraulic cylinder installed eccentric, Axial Fan and tight enough, it will only lead to changes in the quality distribution, the fan rotor will appear a simple quality imbalance failure, the fault spectrum is mainly stable frequency components, each time after the fixed speed Vibration values are relatively stable, will not change with the load conditions. If it is due to the lack of tightening force caused by the installation of the hydraulic cylinder, it will produce unstable quality imbalance, each time after the start again, Axial Fan due to changes in centrifugal force, the hydraulic cylinder position will change, resulting in each boot Of the vibration data are inconsistent, the main vibration frequency to the main, Axial Fan when the speed is constant when the vibration is relatively stable. For such failures, Axial Fan since the vibration after a single fixed speed is very stable, Axial Fan easy to be confused with the original quality imbalance, Axial Fan resulting in unnecessary repeated dynamic balance.