Who can help analyze the reasons?
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Our company’s 200,000-ton sulfuric acid production plant is equipped with a fan driven by a turbine; the turbine drives the fan directly through an intermediate shaft. The bearings are arranged as follows: Bearing No. 1: Shaft bearing on the turbine’s oil motor side (front bearing of the turbine’s thrust bearing). Bearing No. 2: Shaft bearing on the turbine’s coupling side (rear bearing of the turbine). Bearing No. 3: Shaft bearing on the fan’s coupling side (front bearing of the fan, with a thrust bearing as well). Bearing No. 4: Shaft bearing at the fan’s rear end (rear bearing of the fan). On June 13, 2012, the following values were recorded (rotation speed: 4220 r/min): Bearing No. 1: Vertical – 17.21 um; Horizontal – 6.63 um; Axial – ; Remarks: None. Bearing No. 2: Vertical – 1; Horizontal – 3.70 um; Axial – 34.37 um. Bearing No. 3: Vertical – 4.8 mm/s; Horizontal – 2.3 mm/s; Axial – 2.0 mm/s. Bearing No. 4: Vertical – 8.7 mm/s; Horizontal – 6.6 mm/s; Axial – 8.2 mm/s. If the issue lies in the concentricity of the couplings, it should be the bearings No. 2 and No. 3 that exhibit high vibration levels; however, in this case it is Bearing No. 4 that has the highest vibration levels. We would appreciate it if experts could help diagnose whether this is caused by a loose Bearing No. 4 or some other factor
It could be that acid sludge corrosion of the turbine blades has caused a shift in the center of gravity
Another measurement was taken today, and the data is as follows: Parameter, Vibration acceleration (m/s2), Vibration velocity (mm/s), Displacement (μm), Rotation speed. 1# Vertical vibration: 2.2, 0.6, 8, 4146; 1# Horizontal vibration: 4, 6.2, 40. 2# Vertical vibration: 2.8, 4, 26; 2# Horizontal vibration: 3, 4.6, 30. 3# Vertical vibration: 4.2, 6.5, 40; 3# Horizontal vibration: 1.8, 1.8, 14. 4# Vertical vibration: 4, 6.2, 40; 4# Horizontal vibration: 3.6, 5.6, 36. 4# Axial vibration: 4, 3.6, 18
Everything is possible; consider various aspects: check the instruments, footings, couplings, bearings, impellers, review past experience, and even unexpected causes. It’s best to disconnect it for inspection.
The vibration of the fan turbine is very low when it is disconnected
Then check alignment, resonance, and coupling
The impeller has been cleaned, adjusted to a moderate level, and the diaphragm has also been replaced. The suspicion of resonance is mainly due to the absence of a spectrum
The data is provided to the fan manufacturer, who then hires professionals to assist with the analysis. The balance issue is related to many factors; in addition to mechanical reasons, the foundation, electrical systems, and other elements can all affect the balance of the fan.
You can try online dynamic balancing; if the clearances between the blades are fine and there are no issues with the readings from the coupling, then it’s likely that the dynamic balancing is not proper. First, the impeller needs to be thoroughly cleaned – it’s better not to clean it at all if the cleaning isn’t thorough enough. II. Dynamic balancing can be performed online, and weights can be added based on the results of that balancing process; this saves time and has little impact on production.