Zhongtian Hechuang Coal Chemical No. 3 furnace induced draft fan A
1.Equipment Information
Equipment Type: Centrifugal Fan
Rated speed: 991rpm
Related measurement points in this case: Motor non-drive end 1H; Fan drive end 3H; Fan non-drive end 4H
2.Alarm and analysis process
Equipment alarm events:

2.1Analysis process
2.1.1Explanation of trends, indicator parameters and other evidence
The speed vibration at each measuring point of the motor and fan has continued to increase recently.

No. 3 furnace induced draft fan A/fan drive end 3H/8k speed waveform (10-1000)_Equipment Multi-trend
2.1.2Explanation of evidence such as time domain, spectrum, and envelope demodulation
There was no obvious impact on the speed waveforms of the motor and fan at each measuring point.

No. 3 furnace induced draft fan A/fan drive end 3H/8k speed waveform (10-1000)_time domain waveform
The speed spectra of each measuring point of the motor and fan are dominated by the characteristic frequency of the outer ring of the bearing on the output side of the liquid coupling.

No. 3 furnace induced draft fan A/fan drive end 3H/8k speed waveform (10-1000)_spectrum analysis
3.Diagnostic conclusions and recommendations
3.1Diagnostic conclusion
2023-05-31 09:35 Push diagnosis conclusion: The speed of each measuring point of the motor and fan has increased significantly. It is judged that it is related to the abnormality of the bearing on the output side of the liquid coupling, which has deteriorated recently.
3.2Inspection and maintenance suggestions
The equipment is currently in a monitorable operating state. It is recommended to arrange an inspection at an appropriate time. Pay attention to whether there are obvious abnormalities in vibration and temperature at both ends of the liquid coupling. If the abnormalities are obvious, it is recommended to check the damage of the bearing on the output side of the liquid coupling at an appropriate time.
4.On-site inspection and maintenance process
2023-06-13 23:58 On-site engineer Wu reported that the 6040 bearing on the output side of the liquid coupling was replaced, and the bearing raceway was obviously damaged.
5.On-site inspection and maintenance photos
The inspection photos show that there is obvious circumferential damage to the inner and outer ring raceways of the bearing, and the damage is located on one side, indicating that there is an unbalanced load during the operation of the bearing, resulting in obvious force on one side and wear due to long-term operation. From the signal, the fault characteristics of the outer ring of the bearing are obvious. Although the inner ring is also damaged, no obvious characteristics of the inner ring of the bearing can be seen. It is speculated that the damage to the outer ring is more obvious, resulting in the lack of characteristics of the inner ring. The damage results also verify this.

Maintenance photo_1
Maintenance photo_2
Maintenance photo_3

Maintenance photo_4

Maintenance photo_5

Maintenance photo_6
6.Verification after inspection and maintenance
After overhauling and replacing the bearings, the speed vibration at each measuring point of the motor and fan dropped significantly, and the trend became flat.

No. 3 furnace induced draft fan A/fan drive end 3H/8k speed waveform (10-1000)_Equipment Multi-trend
After the bearings were overhauled and replaced, the amplitude of the speed waveform at the fan measuring point dropped significantly.

No. 3 furnace induced draft fan A/fan drive end 3H/8k speed waveform (10-1000)_time domain waveform
After the bearing was overhauled and replaced, the damage characteristics of the outer ring of the fluid coupling bearing in the velocity spectrum disappeared significantly, and the spectrum amplitude decreased significantly.

No. 3 furnace induced draft fan A/fan drive end 3H/8k speed waveform (10-1000)_spectrum analysis
7.Customer feedback form
None
8.Monitoring fault range
Timely and effective collection of equipment operating status data (vibration, temperature) is subject to the constraints of network connectivity and data transmission time, and also needs to consider interference from factors such as the equipment's own attributes and production processes. At the same time, the analysis and diagnosis of equipment status is based on changes in vibration effects caused by rotating parts failures. Therefore, the status monitoring system cannot guarantee monitoring of all types of faults. The monitoring system is configured according to the measurement point scheme recommended by Party B, and the range of faults that can be monitored and the description are as follows:

9.Notes
1. If the client of this report cannot provide basic unit parameters (such as unit transmission chain diagram, gearbox structure diagram, gearbox teeth number, related bearing models and brands), the accuracy of analysis and diagnosis will be affected;
2. This report is the analysis, diagnosis and maintenance opinions of the unit by Rongzhi professional technicians, which is for reference only. The specific maintenance and repair measures shall be decided by the client.
3. This report shall not be used as evidence for any claims, litigation, etc.;
4. The client has the obligation to keep the analysis report confidential and shall not provide this report to a third party, print it into other promotional materials, or publish it on the Internet or other public information platforms without the written permission of the trustee.