Greenfield Ethanol Failure Cause Analysis


Continuously Monitored using Vibration & Ultrasound Analysis

This BF-9401 Area Pulling Fan plays an integral role in Greenfield Ethanol’s manufacturing process. It is a critical component to their Thermal Oxidizer Equipment. If this fan goes down, production is severely hindered, and possibly even stopped all together.

                                  Vigilant System Permanent Install on Critical Fan Bearing

Understanding the Asset

The asset is a New York Blower with a 250hp motor that rotates 1780 rpm. The fan rotates at 1168 rpm 24/7, all day, every day. The fan shaft is mounted with two SKF 22232 bearings, they’re lubricated with oil.

The last time the fans bearings were replaced was October 22, 2012.

Vibration & Ultrasound Analysis, September 2022

Lead Vibration Analyst, Jonathan Dion takes routine vibration measurements on this plant’s critical equipment. Back in 2018, a defect was detected on the pulley side of the fan (SKF 22232). It has since been evolving. Using the acceleration envelope filter in Peakvue, it can be seen clearly.

                                              Figure 1 – Envelope Spectrum (Peakvue)

The following ultrasound readings were taken on September 9, 2022, helping confirm the findings from the Vibration readings.

                                         Figure 2 – Ultrasound Readings (UAS3)

Vibration & Ultrasound Analysis, November 2022, Vigilant System

With no plan to replace the bearings until the large-scale planned shutdown in September 2023, the best course of action decided by the reliability team was to install a Vigilant System to continuously monitor the condition of the fans bearings, and hopefully see the assets life extended until the planned shutdown.

The Vigilant System is an 8-Channel Online Condition Monitoring Solution that combines the versatility of ultrasound and the analytics of vibration. Vigilant comes standard with its own embedded software that any member of the reliability team can access using the correct network credentials.

                                                                                  Vigilant System

The Vigilant provides reliability teams with a means to continuously monitor critical assets that are heavily guarded, or in this case as they near their end of life.

See how the Vigilant was configured below:

  • M2H horizontal drive motor
  • F1H : fan side drive Horizontal
  • F1A : fan side Axial drive
  • F2H : fan opposite drive side Horizontal
                         Figure 3 – Vibration Sensor Configuration & Dashboard (Vigilant’s Embedded Software)

Vibration & Ultrasound Analysis, February 2023, Vigilant System

The reliability teams focus was monitoring data collected by the F1H Accelerometer.  Monitoring technicians split their windows into 4, all with different lines of resolution as to see rapid changes as well as changes over a long period of time.

                                                       Figure 4 – Vigilant Window Configuration

A Closer Look at Each of the 4 Windows

                            Window 1 – Max. Frequency 10000hz, Lines 12800, Averages 6 – February 2, 2023
                 Window 2 – Time Waveform – Duration: 4.485 seconds – Points: 114817 – February 2, 2023
  Window 3 – Envelope Spectrum – High-Pass Freq. 2000hz, Max. Freq. 1000hz, Lines 3200, 1 Average – February 2, 2023
Window 4 – Envelope Time Waveform – High-Pass Freq. 2000hz, Duration: 5.05 seconds – Points: 12800 – February 2, 2023

Concluding Thoughts

With the Vigilant system in place, constantly monitoring the condition of the fans faulty bearing, the maintenance and reliability team at Greenfield Ethanol can safely extend the life of this fan, possibly even until the next scheduled shutdown in September, 2023.

But just in case, alarm management was set up with the plants DCS to trigger email alerts if the condition of the fans bearings decreases to dangerous levels.