U.S. Army Corps of Engineers officials found a Voith Hydro scale model turbine met or exceeded their requirements for replacement hydropower turbines at 135-MW Center Hill Dam in Tennessee.
Representatives from the Corps' Hydroelectric Design Center and its Nashville District visited Voith labs in York Oct. 6-9 to witness scale model testing that the Corps said was "completely successful" and will keep rehabilitation of the Center Hill project on track.
The Nashville District awarded a $47.2 million contract to Voith in June to refurbish Units 1, 2 and 3 in the Center Hill powerhouse, which began operation in 1950 and 1951. Work is to include replacement of runners, wicket gates, and generator stator windings; refurbishment of servomotors and the unit braking system; restacking existing generator iron; and installing vibration monitoring and high-pressure thrust bearing oil lift systems.
Hydroelectric Design Center mechanical engineer Ryan Sollars said he looked closely at efficiencies, cavitation, dimensional tolerances, draft tube pressure pulsations, runaway speed of the runner, wicket gate torque and validity of checks being conducted.
"The goal is to verify you are not going to have any issues with these units and they generally last for many years ... 40, 50, 60 years. So it's important that you get high efficiency," Sollars said. "We witnessed checks through the entire operating range and found that Voith Hydro has exceeded the contract requirements."
During the witness test, Nashville District personnel stood underneath the scale model turbine and watched it operate through Plexiglas. The lab technicians applied different operating conditions to demonstrate the turbine's efficient operations.
The new turbines also are to feature openings in the edges of the turbine blades to introduce air into the water as it flows through the generating unit. The venting feature is to elevate dissolved oxygen levels in the water benefitting aquatic life.
Rehabilitation of the Center Hill units is the start of a 20-year process to rehabilitate all 28 turbine-generators at hydroelectric plants in the Nashville District. A memorandum of agreement between the Corps and the Southeastern Power Administration and power customers provided a funding stream for the units' rehabilitation. Over the life of the program, SEPA is expected to direct more than $1.2 billion into the hydro equipment rehabilitation.
The Corps awarded a contract last year to Terracon Consultants Inc. for geotechnical engineering services, primarily at Center Hill and the 270-MW Wolf Creek Dam in Kentucky. The Corps also requested information last year on contractors capable of constructing a roller-compacted-concrete berm to reinforce an earthen saddle dam at Center Hill.