Generator Rebuild and Unit Refurbishment for the Wells Hydroelectric Project NWHA Spokane October 30, 2014 0
The Wells Project WELLS Chief Joseph Rocky Reach East Wenatchee Wells Dam Location Columbia River river mile 516 30 miles downstream of Chief Joseph Dam 42 miles upstream of Rocky Reach Dam Rock Island Wanapum 1
Wells Project Overview One of five non-federal mid-columbia hydro projects o 10 generators with peaking capability of 840 MW o Allis-Chalmers Kaplan turbines 85.7 rpm, 65 feet o Unique hydrocombine design o Commercial operation in 1967 o Average annual generation of 4.1 million MWh Previous repairs and replacements o Rewound all ten generators in the mid-1970s o Replaced all ten turbine runners in the late 1980s o Runner replacement by Fuji Electric based on a combination of bid $ and results of competitive model testing at an independent lab o Replacement runners were approximately 5% more efficient than original Allis-Chalmers runners o Rewound Unit No. 1 stator in 2006 2
Wells Project Aerial 3
Wells Project Layout 4
Hydrocombine Section Through Unit 5
New Fuji Runner in 1989 6
Wells Project Generator Rebuild Project Scope All 10 generators will be rebuilt and turbine components will be refurbished New stators with Roebel bars instead of original multi-turn coils New turbine guide bearings with adjustible shoes vs. original journal type New turbine shaft seal Re-machine discharge rings New generator instrumentation and air gap monitoring Re-shrink rotor rim and re-insolate rotor poles Refurbish everything else for a 40 year life Perform CFD analysis and model testing Stay vane extensions for efficiency increase Finite element, fatigue analysis of all components Mandatory facilities for site logistics Fixed $ on first three units Escalation clause for remaining units 7
CFD and Model Testing 8
Site Logistics and Mandatory Buildings COLUMBIA RIVER BUILDINGS A AND B BUILDING D BUILDING C 9
Site Logistics Generator Rotor Pedestal 10
Project Schedule and Progress Original contract was about 9 months per unit $151,000,000 base contract without escalation About 30 change orders through first unit o A little over $2,000,000 within 10% planning budget o About 11 months added for unexpected scope o Expect 12 months per unit on remaining units First unit completed October 2013 about three years over contractual requirement o Liquidated damages maxed out at 15% of contract plus change orders o Thrust bearing wipe during commissioning in April 2012 o Thrust bearing wipe during commissioning in December 2013 First unit is back out of service for warranty repair o New turbine guide bearing failed in service o Complete redesign of new turbine guide bearing o Commissioning now scheduled for November 2014 Our project superintendent now has white hair 11
Some Lessons Learned to Date It is vital to have inspection and test procedures approved ahead of the outage Analyze everything with respect to future service life o We found a major crack in our 450 ton rotor lifting device Surprises will happen o Unexpected amount of wear on our bronze blade trunnion bushings o Substantial voids in the concrete behind our discharge rings Our contractor relied too heavily on subcontractors Turbine shaft, generator shaft and thrust runner should not be machined at separate shops o Contractor machined generator shaft and was unable to achieve runout Concrete structures (and generator frames) undergo seasonal changes in shape Contractor s key staff are critical both site supervision and skilled labor Take advantage of the opportunity for example, refurbish trashracks The Shalls sometimes you need to compromise to have your project be successful 12
Turbine and Generator Shafts in the Shop 13
Generator Rotor Lifting Device 14
Original Construction Reinforcing Steel 15