As part of the modernization of the Norwegian hydroelectric power station Raanaasfoss 1, new turbines were installed with Thordon SXL series water-lubricated guide bearings, which even after 23,887 hours (33 months) of continuous operation showed virtually no wear.
In 2013, Voith Hydro upgraded the Raanaasfoss 1 hydroelectric power station, which was built back in 1922, by installing new 13.5 MW turbines where water-lubricated guide bearings were used. During planned inspections of the turbines put into operation, it was found that the Thordon SXL series guide bearings showed almost no wear with a measured bearing clearance of less than 0.30 mm on the longest running block 1. All other turbines (blocks 2-6) had very low measured diametrical clearances from 0.30 to 0.50 mm. The initial design clearance of the SXL guide bearings was 0.65 mm.
¡°We are very pleased with the operating results of the water-lubricated guide bearings. Compared to oil-lubricated systems, maintenance and monitoring have become significantly less time consuming. Operating costs have also declined since we no longer need to buy lubricants, ¡±said Bj?rnar Petersen, mechanical engineer at Akershus Energy, which owns the hydropower plant. ¡°Although economic factors were key when deciding on the choice of bearings, environmental issues were also the focus of attention.¡±
Choosing a water-lubricated solution for the lower guide bearing instead of the more traditional oil-lubricated design allows the bearing to be cooled and lubricated with the same river water that feeds the turbine.
Water-lubricated bearings completely eliminate the risk of oil leakage contaminating the turbine drain or associated water, which could happen with old bearing assemblies. A water-lubricated bearing not only helps protect the environment, but also provides operational and maintenance benefits over original oil-lubricated bearing systems. In particular, for Thordon bearings, downtime for inspection is extremely reduced. In addition, experience has shown that they work 3-4 years longer compared to oil-lubricated counterparts.
Many operators who previously switched to Thordon water-lubricated hydrodynamic bearings have already recouped their costs by saving on lubricants and a longer service life.
