that downtime is at a minimum of 2. 5-3 days. When they tried to work with a planned shutdown schedule, the shaft seal would fail before the shutdown.

Simply put, no matter what they tried would not work, and they faced an ongoing, costly, time-consuming solution to a decades old problem until they installed the Inpro/Seal Air Mizer shaft sealing system.

Inpro/Seal’s bearing isolator is a non-contact, no-wearing labyrinth seal that provides users of rotating equipment with permanent bearing protection. Its two parts – a rotor and a stator – interact with each other to keep contaminants out of a bearing enclosure while keeping lubricant in.

The maintenance staff at Port Townsend knew about Inpro/Seal, as they had been using their bearing isolators on select pumps and screens and had been working with Boyd Evenson (regional manager) and Lena Hunt (local representative).

According to Boyd, “In 2005, during a routine visit,
Lena and I told them about a shaft sealing system —
the Air Mizer - that had come into its own. Frankly, I
never really knew about their lime kiln problem, but
they did. As soon as I showed this system to Terry, Greg
Knowles and their maintenance people, they immedi-
ately recognized its potential to solve their problem. It
was like a light bulb got turned on.”
For about 10 years, Inpro/Seal had been receiving
a large number of end user requests for a long lasting
shaft seal that could be used on equipment where
wet or dry particulates, powders and slurries were
handled, processed, packaged and stored.

In 1999, following extensive R&D, field testing and laboratory trials, Inpro/Seal unveiled its first shaft seal, the Air Mizer-PS, a modification of its bearing isolator. A compound labyrinth, it was adapted to incorporate an air purge containment system. Its unique design uses a solid wall of air, which functions as a barrier for contamination to retain product where it should be: in the equipment, not outside of it.

End users widely accepted the initial Air Mizer-PS for its ability to boost overall reliability, reduce costs, extend sealing efficiencies and increase bottom line results without equipment modification, and they wanted more. By 2004, an entire product line began to evolve with the addition of Articulating Air Mizer and Smooth Bore designs.

Fan housing covered in lime dust that was leaking out of the fan housing

THE BOTTOM LINE

In summing up, Rohring says, “Before we met with Boyd and Lena, we tried a number of different methods to seal the fan bearing housing. No matter what we tried, nothing worked. For years, we just accepted the fact that lime dust was going to contaminate the fan bearing housing. We also had to acknowledge the fact that there was no way to plan this. Sooner or later, we knew we would face 15-24 hours of lost production due time to lime kiln maintenance. Adding to the problem was that we did not know when. As a maintenance professional, it was hard to accept having to deal with a 100% chance of failure.

“In the old days, if the fan failed completely, we would have had to shut down the lime kiln and possibly even the entire mill to replace the fan bearing,” Rohring concludes. “But that was then. This is now. We installed the first Air Mizer in the fall of 2005. Due to the high operating temperatures, we had to do some tweaking, including the addition of a special design adapter plate to compensate for the poor condition of the fan housing. We also had to make adjustments to compensate for axial shaft movement. Since that time, we have not had to shut down a single time to replace the fan bearings in our lime kiln. It appears that this problem has become a thing of the past.” PPI

To read more articles on Mill Maintenance & Upgrades, visit our Mill Maintenance & Upgrades Technology Channel at www.risi.com/ technologychannels/millmaintenance