Energy Keepers, Inc., Montana

Soon after Energy Keepers, Inc., a Corporation of the Confederated Salish & Kootenai Tribes, took over operation of the SKQ Hydroelectric Facility (formerly Kerr Dam), the generator was taken off line due to a thrust bearing temperature alarm. The 112,646 horsepower Francis turbine 90 MW generator’s thrust bearing had failed due to operational error and thrust loading that approached the design limit of the original thrust bearings. After a root cause analysis was performed, it was determined the best path forward was to install PTFE lined thrust bearings due to their higher load capacity and greater efficiency which would allow for cooler operating temperatures. Hydro Tech Inc. was contracted to design and supply the new PTFE thrust bearing.

After approximately one year of operation, four times daily temperature recordings revealed that the PTFE thrust pot oil temperature trends were approximately ten degrees Celsius (10°C) cooler than the previous design within the same operating parameters. The oil will therefore last longer due to the lower operating temperature conditions. Previous oil samples and tests had already shown signs of oil breakdown (lubricants were being depleted) only five years after the new Francis turbine runner was installed in 2007.

This paper will show recorded data about our experience with the new PTFE thrust bearing and the thrust loading that pushed the original thrust bearing to its limits. The bearing pad temperature monitoring was upgraded to include all eight (8) pads versus the previous monitoring that included only two thrust pads. Also, the paper will compare start-up bearing run temperatures from March 2007 versus February 2016.

In addition, the generator guide bearing (located in the same bearing pot as the PTFE thrust bearing) experienced a complete failure. The thrust bearing operated with Babbitt circulating throughout the thrust bearing pot, and with Babbitt moving past and over the PTFE thrust bearing for a period of six weeks. The results of damage to the PTFE pads (manufactured by EnEnergo (Russia)) are discussed in this paper.