MDI Case Study: Kiln Hood Fan

Thank you to our educational collaborator MDI for this tech tip

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Introduction:

In this case study, Machinery Diagnostics Institute (MDI) was commissioned to address a high vibration issue on a kiln hood fan at a construction plant located in Queensland, Australia. Effective vibration analysis plays a crucial role in identifying such issues before they lead to further damage or unplanned downtime.

Analysis:

MDI utilized the following condition monitoring hardware solutions to analyze the kiln hood fan and determine the root cause of its elevated vibrations:

A render of a CTC AC292 compact size, top exit industrial accelerometer.
AC292
Premium compact size accelerometer, 100 mV/g, 5%

A render of a CTC MH137-1A multipurpose mounting magnet for industrial accelerometers.
MH137-1A
Curved surface mounting magnet, 15 lbs. (6.8 kg) pull strength

A render of a CTC cable assemble with CB108 coiled cable, C395 connector on left, K2C connector on right, and a safety feature in the middle.
CB108-C395-006-K2C-SF
CB108 coiled cable with C395 connector on the left, a safety feature in the middle, and a K2C connector on the right.

CommTest Data Collector

Chart 1:

Machine Layout:

Kiln fan machine layout photos.

The Fan Drive End (FDE) - horizontal direction - vibration spectrum shows vibration levels of 0.9 mm/s RMS at the running speed of 1451 RPM - 80% - after fan balancing:

A graph of Kiln Fan vibration levels after balancing.

The Fan Drive End (FDE) -horizontal direction - vibration spectrum shows vibration levels of 0.9 mm/s RMS at the running speed of 1451 RPM - 80% - after fan balancing:

A graph of vibration levels after fan balancing.

Polar Plot:

Standards:

Comments and Recommendations:

The fan shows acceptable vibration levels according to the ISO 20816-3 Standard at 80% of its running speed (approximately 1451 RPM). However, at 60% of the running speed (around 1080 - 1099 RPM), the vibration levels were relatively high. This is due to the fan operating near the natural frequency of the machine base, causing resonance. To avoid resonance issues, it is recommended to avoid running the fan in the 1080 - 1099 RPM range.

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