Bearings play a great role in ensuring these goals are met with bearing reliability being especially paramount. Traditionally, greased bronze bearings have been used in hydropower applications due to their historical success and the industry’s familiarity with them. Despite this, it is known that greased bearings increase the risk of turbine failure if not properly maintained, amount to extra annual costs through grease/lubricant purchases, consume personnel time for maintenance, and pose the risk of environmental contamination.
In fact, 15% of rotor, wicket gate, and turbine failure is attributed to issues with lubrication while another 7% is attributed to bearing wear. Another 8% is attributed to both lubrication and wear related issues. As shown, bearing choice has a significantly impact on the operation of hydropower plants.
THE COSTS OF GREASED BEARINGS
Bearing failure is a costly event for hydropower plants that can require up to 3 months of downtime for replacement – a loss in revenue of almost $4 million for a 30 MW plant. Improper maintenance of traditional bronze bearings, such as missing a single grease injection or applying an insufficient amount of lubricant, increases the possibility of bearing failure.
In addition to increasing this risk of failure, the cost of greasing bearings adds up annually. Regular bearing lubrication is a time consuming process for mechanical technicians, generally requiring two hours of a technician’s day to maintain greasing equipment. Between personnel time and grease usage, over $8,100 per technician is spent annually to ensure uninterrupted plant operation with lubricated metal bearings!
Furthermore, if grease or oil is leaked into the environment a plant could face cleanup costs of around $120 per gallon – this not including the costs of other fines.
BENEFITS OF FIBER REINFORCED COMPOSITE BEARINGS
PTFE-containing composite bearings provide superior low-friction performance in hydropower applications. These bearings also have a greater tolerance for misalignment as well as lower stick-slip than traditional bronze bearings, lowering the risk of improper operation. The low-friction performance of these bearings also results in substantially longer bearing life than greased bearings, leading to longer plant runtimes between bearing refurbishments.
In addition to their performance benefits, composite bearings require no regular maintenance, lowering annual operating costs. Removing the need for grease also eliminates the possibility of environmental contamination, saving a plant from the possibility of potential fines and cleanup costs. Below is one example of how GGB’s global team of engineering experts helped a customer receive these benefits by designing a custom fiber reinforced composite (FRC) bearing for their hydropower application.
CHINA’S JIXI PUMPED STORAGE POWER STATION
In 2016, GGB was approached by Dongfang Electric Company for a tight tolerance bearing solution for their pump storage facility located in JiXi, Anhui province, China.
While tight tolerances are becoming the norm across the industry, this facility in particular required bearings with an allowance for eccentric machining of the bearings’ bore after installation to meet a yet to be determined offset.
To deliver an appropriate bearing, GGB’s cross functional team of engineers ran an extensive machining study to investigate which fiber matrix would provide the best machining response while not compromising on tribological performance.
Ultimately, it was found that HPMB® high precision fiber reinforced composite bearing with a thick, machinable tribological layer, best fit the needs of the facility.
GGB’S RANGE OF HYDROPOWER BEARINGS
Fiber reinforced composite bearings are no longer a commodity.
Having successfully proved themselves in the hydropower industry over the past 20 years, they are the successor of greased bronze bearings.
GGB FRC bearings, including HPM, HPMB®, and HPF® filament wound bearings, are especially suitable for hydropower applications with liners specifically designed to minimize stick slip and reduce friction.
Top OEMs such as Voith and GE choose GGB fiber reinforced composite bearings due to how they tolerate misalignments and handle edge load better than bronze bearings.
Additionally, GGB fiber reinforced bearings have been tested by the US Corps of Engineers to have a life expectancy of over 30 years.
All in all, GGB hydropower bearings reduce plant operation interruptions, eliminate the need for grease or oil lubricants, and reduce costs through their maintenance free design. With our hydro bearings being used in hydropower plants globally from Xiangjiaba in China to Belo Monte in Brazil, GGB has the plain bearing solution for any hydropower application.
To learn more, watch the video of GGB's presentation on composite bearings for hydropower industry made at the 2017 HYDRO International Conference.