Better Blades Yield More Power
|
THE MAGAZINE DEVOTED TO NICKEL AND ITS APPLICATIONS |
 |
A THIRTY-TONNE stainless steel runner and shaft is lowered into place at the Sir Adam Beck No. 2
generating station in Ontario, Canada. The replacement resulted in a 3-4% increase in plant output. |
 |
A STAINLESS STEEL Francis runner. By designing better blades with higher strength materials utilities can
produce more electricity from existing hydroelectric generating stations. In Ontario, seven such replacements
has increased generating capacity by 400 Megawatts. |
|
|
Runner blade replacements increase capacity by 400 Megawatts by Carroll
McCormick
Nickel Magazine, December 2006 -- Since 1992, Ontario Power Generation (OPG) (formerly Ontario Hydro) in central Canada has been increasing the power output from its hydroelectric turbines, or units, by replacing runner blades with better-designed, higher-strength blades cast from nickel-containing stainless steel J91540.
By 2005, OPG had completed runner blade replacements at seven hydroelectric stations for an increase in capacity of 400 Megawatts (MW).
And the gains keep coming, says Mario Mazza, director of Hydro Business Support: “Five units at three different stations are being upgraded in 2006, adding a total of 26 MW. Over the next five years another 65 MW is planned at several stations, and the program will continue beyond 2011.”
To put these figures in perspective, the additional output is almost exactly half the power
output of one of OPG’s Pickering CANDU nuclear reactors, yet the gains involve no new infrastructure or
environmental impact. “Public support for hydro power strengthens the business case when compared with
spending money on alternative ways to get more energy or capacity,” says David Abbott, director of public
affairs with OPG.
The province of Ontario needs the additional power. “The Ontario Power Authority's Supply Mix Advice Report
(December 2005) states that the combination of demand growth and generation retirements would create a gap of
roughly 24,000 MW by 2025, equivalent to about 80% of Ontario's current capacity,” Abbott says.
Two plants account for more than half the gains to date: Sir Adam Beck No. 2 generating station, near St.
Catharines, obtained a per-unit increase of 12.1 MW (an increase from 81.6 to 93.7 MW per unit) for a total
of 194 MW, or a 3-4% increase in plant output. The runners for the station’s 16 Francis-type turbines were
replaced with lighter, 30-tonne cast J91540
runners containing 4% nickel. The plant upgrade was completed in 2005.
This alloy has good corrosion resistance, and cavitation resistance comparable to S30400. OPG maintenance
personnel believe the new blades will require fewer and shorter out-of-service days for repairs; a single
unit’s daily power production can be worth as much as C$100,000.
The alloy’s weldability is important for any in situ cavitation repairs; field repairs with
austenitic material can be done with minimal pre-heat and no post-heat weld treatment, according to the
United States Department of the Interior’s Facilities Engineering Branch, Engineering Division, Denver
office, Colorado. Its high strength is important, as increasing the efficiency of a blade also increases the
differential pressure between its pressure side (above) and suction side (below).
The RH Saunders station in Cornwall, Ontario, obtained an increase of 118 MW over 15 units; its upgrade was
completed in 2002. OPG replaced 72 runner blades, weighing 5,200 kilograms (kg) apiece, with J91540.
Each blade had a cast weight of 6,000 kg before milling and grinding. The new blades increased each
unit’s capacity to between 64 and 65.4 MW from 56 MW.
Further runner blade upgrades will add another 150 MW of generating capacity to the OPG system by 2015.
PHOTOS: Ontario Power Generation
 Dave Abbott Director of Public Affairs Ontario Power Generation Tel: 1-416-592-3868 Email: dave.abbott@opg.com Web site: www.opg.com |
