October 14, 2009
by Steve Gahbauer, Contributing Editor
Photo: Big Ass Fans
Industrial fans and blowers are a critical part of many industrial processes and as productivity requirements grow, increasing demands are put on their performance and reliability.
Higher rotational speeds mean higher operating temperatures and many fans are used to evacuate hot gases that range in temperature from 100 to 600 degrees C. Some of this heat is transferred to the bearings via radiation and conduction in the fan shaft. Thus, operating under high temperatures can lead to bearing failure that causes unplanned outages, unnecessary downtime and production and profit losses.
High operating temperatures also have a negative impact on bearing lubrication and the service life of the base oil. Degradation of the lubricant means increased friction, inadequate lubrication and possible bearing failure.
Bearings in fans and blowers situated in high-temperature environments often operate at their limits, but it’s possible to upgrade industrial fans by looking at bearing improvement. The results will more than justify the expense. What’s more, the benefits are important for energy conservation and sustainability.
Bearing expertise, knowledge about seals and experience in lubrication have enabled SKF to develop a standardized solution for upgrading fans. The Swedish-based global bearing manufacturer has come up with a self-aligning bearing system that generates lower friction and uses specially designed housings that are optimized for use with circulating oil lubrication. A condition-monitoring system—also part of the system—provides early warning of potential bearing failure.
A fan upgrade starts with a functional analysis of the equipment and involves a number of components, each with its own contribution towards lowering bearing operating temperatures. Circulating lubrication does just that, and reduces maintenance costs. The unit provides cool, clean oil to each bearing and is the most important component in the temperature-reducing solution.
But such systems are complex and all components are important to provide a real upgrade.
A large tank allows enough time for the oil to settle and de-air. During operation it also has the advantage of enabling the oil to cool before it’s used again. The tank contains a heater that raises the oil temperature at start-up so the appropriate viscosity is maintained at all times. A high-capacity filter cartridge removes polluting particles from the oil.