Up Time Magazine- June/July 2008

it was having an effect on the acidic air entering the blower. The testing indicated the activated carbon was nearing depletion between 5,000 and 6,000 hours. The average run time per year is 4,500 to 5,500 hours (these blowers are rotated) so a yearly PM was established to change the activated carbon elements. With the original air inlet filtration set up, both filters needed to be changed on a monthly frequency for a cost of almost $49,000 per year for three blowers. Even with the increased cost of the better filters, the new three stage set up has the pre-filter changed monthly, the second filter changed every two months, and the carbon filter changed once per year based on activated carbon depletion. The three stage filtration cost is only $39,000 per year for three blowers. Not only is this an operating cost savings of $10,000 per year but we are getting better air filtration plus acid mist removal. This should also increase our inspection/rebuild frequency, which is another significant cost savings as well. Figure 7 - Control Vane of 25,000 CFM Blower The original two stage air inlet filtration which existed of a cellulose two inch pre and six inch post filter were replaced with a three stage filtration set up. The new set up utilizes a synthetic media, three ply pre-filter, a twelve inch v-pak type which has almost twice the original surface area and the final filter, a twelve inch activated carbon element. The activated carbon element was used to neutralize the acid mists and tested at 2,000, 4,000 and 6,000 hours to determine the depletion of activated carbon and assure Figure 8 - Inner Race Fault in Bearing Most of this article has been related to optimizing lubrication related PdM, (hey I’m the oil guy). What about the other technologies and the information they can provide? Vibration data can provide a wealth of information about rolling element bearings, gear sets, coupling problems, misalignment, resonance, and soft feet to name a few. The inner bearing race in Figure 8 is an example of specific component identification through vibration analysis. This 1,200 HP motor is located directly underneath hydroclone, which separates and mixes water with limestone before it goes into the ball mill. A significant leak almost buried this motor in lime slurry. The next month’s vibration route indicated a problem with the motor inboard bearing inner race. As part of our PdM program we are present during motor disassembly for routine and known problem motors. Once the evidence has been disturbed or accidentally thrown out, root cause analysis becomes hard, if not impossible, to perform. In this case the root problem, an occasional overflow or leak cannot be eliminated, so a roof was built over the motor and gear reducer to help minimize another bearing failure due to lime slurry. In another case, we had a crack develop in one of our coal ball mill ring gears. It was first identified through vibration data and monitored closely for almost a year until we were able to schedule the gear replacement. This allowed normal ordering of parts and scheduling the workforce, rather than incurring the 50 june/july 2008 http://www.sdtnorthamerica.com http://www.sdtnorthamerica.com

Table of Contents Feed for the Digital Edition of Up Time Magazine- June/July 2008

Up Time Magazine- June/July 2008 Contents Upfront Upclose: The True Cause of Most Machine Failures Information Technology: Finding Future Perfect Lubrication: Building an Oil Analysis Winner Maintenance Management: Hidden Ways to Increase Safety Infrared: Air Barriers Lower Energy Costs, Increase Profits Motor Testing: Efficient Motor Repair, Part Deux Precision Maintenance: Good Maintenance, Smart Maintenance Reliability: Common Errors in Root Cause Analysis Ultrasound: Avoid the Baghouse Blues Vibration: Don't Let Your Sensors Get Eaten Alive Upgrade: Lining It All Up

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