Advanced Fault Diagnosis for Updraft blower in Steel Industry

Case Study

Advanced Fault Diagnosis for
Updraft blower in Steel Industry

1. Abstract

Fans and blowers used in the steelmaking process are required to have high reliability and high efficiency for stable operation over a long period in harsh environments. However, fan bearings failure is one of the highest risk events in the steel Industry. Running of such fans under a fault condition is highly dangerous and could damage other drive components. This paper, with the help an actual use case, demonstrates the use of Infinite Uptime’s auto-diagnostics features to help detect faults in fan bearings.

2. Introduction

The Up-draft blower indicated in Figure 1 (schematic) is installed at a galvanized steel coating process of one of India’s biggest Steel manufacturers. Sensor nodes enabling fault diagnosis for this are mounted at positions marked in dots. These sensor nodes communicate to a cloud dashboard and provided comprehensive vibration signal analysis and fault diagnosis.

Figure 1: Blower Construction & Sensor Positions

3. Background

3.1 Updraft Fan

The Updraft fan is a simply supported centrifugal fan which handles air of different temperatures in the updraft drying zone to remove moisture from the pellet bed in the steel plant. The drive from the main motor to the fan is obtained through a rigid coupling and the fan impeller is positioned between the bearings. The fan bearings are inside the plumber block and are grease-lubricated.

3.2 Sequence
of Events

Figure 2 shows the sequence of events from fault diagnosis to corrective action.

4. Solution

The plots presented in this section validate the presence of the fault as predicted by the system. Figure 3, Figure 4 show increase in trends. Figure 5 indicates bearing defect frequencies captured in the spectrum. Figure 6 shows decrease in Total Acceleration after bearing replacement.

Advanced Fault Diagnosis in IDAP Platform

A. High Total Acceleration since installation in April 22.

Figure 3: Increase in Total Acceleration

B. High Velocity Values in all 3 directions from 17-04-2022 to 28-04-2022.

Figure 4: High Velocity Values

C. Shockwave Spectrum – Outer Race defects observed in the spectrum.

Figure 5: Bearing outer Race defect in Shockwave Spectrum

D. Decrease in Total Acceleration values after bearing replacement

Figure 6: Trend reduction observed after bearing replacement

5. Site Inspection and Findings

Inspection and replacement of bearing no. 22234 was done by maintenance team done on April 17. The disassembled bearing as shown in Figure 7 has indications of fluting marks on the outer race. Such fluting marks are results of an electrical current leakage.

Figure 7: “Fluting Marks” on outer race

6. Conclusion

The breakdown of such blower will result in a production loss of up to 12 hours or even more. The paper serves to demonstrate that bearing faults in an industrial fan can be monitored and effectively diagnosed by accurate spectral analysis and trending total acceleration. Thus, preventing unplanned downtime for this equipment.

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