YORK, Pa. (Oct. 13, 2014) -- U.S. Army Corps of Engineers experts witnessed a series of tests this week on a "small-scale" turbine model in a laboratory at Voith Hydro Inc., here.
The tests were completely successful, and the positive results will keep the Center Hill Hydropower Rehabilitation Project (Tennessee) schedule on track.
The U.S. Army Corps of Engineers Nashville District awarded a $47.25 million contract to Voith Hydro, in June 2014, to rehabilitate three Center Hill Dam hydropower units. Voith designed the turbine, built a to-scale turbine model and then operated it to ensure it meets design specifications.
Voith Hydro technicians put the model through its paces, Oct. 6-9, while representatives from the Hydroelectric Design Center in Portland, Oregon, verified the results.
Ryan Sollars, mechanical engineer with HDC, said Voith Hydro provided the U.S. Army Corps of Engineers a model test report several weeks ago. He previewed the report and then witnessed and verified the data points provided.
Sollars said he looked closely at efficiencies, cavitation, dimensional tolerances, draft tube pressure pulsations, runaway speed of the runner, wicket gate torque, and even the validity of the 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 explained. "We witnessed checks through the entire operating range, and found that Voith has exceeded the contract requirements."
The Nashville District also sent a small team of experts to the lab Oct. 8, to receive a briefing, ask questions and witness the operation of the model turbine.
Jeff Linkinhoker, project manager; Jamie James, Hydropower Rehabilitation Program manager, Jesse Pullen, resident engineer; and Mike Murphy, mechanical engineer with the Hydropower Branch; spent a lot of time interacting with lab officials conducting the testing.
"Obviously we want to make sure that when the turbine generator is rehabilitated that it runs exactly like it's supposed to," Linkinhoker said.
During the witness test, Nashville District personnel stood underneath the turbine and watched it operate through Plexiglas. The lab technicians applied different operating conditions to demonstrate the turbine's efficient operation.
Francisco Kuljevan, hydraulic engineer with Voith Hydro, said the model testing conducted at S. Morgan Smith Memorial Laboratory, measured the performance of the turbine to ensure it meets the required specifications before the manufacturing process and work to modernize the power house begins. The witness test also provided them an opportunity to showcase the turbine and demonstrate that it meets or exceeds the Corps of Engineers' requirements.
"I think that the different conversations that we have had have been very effective, and so far I feel the [Corps of Engineers] has gotten a good feeling of what they will be getting from Voith," Kuljevan said. He added that the great thing about the laboratory is the ability to simulate any condition, which makes it easier to test the hydraulic design of the turbine.
Although not part of the testing this week, the turbine will also include an important environmental feature. Openings in the edge of the turbine blades will introduce air into the water as it flows through the hydropower unit. The venting feature will elevate dissolved oxygen levels in the water, which benefits aquatic wildlife.
"We have the conditions that the [Corps of Engineers] has given us, so we know what the starting point of the air (dissolved oxygen levels) in the water is. And from that starting point we can actually calculate or simulate how much air we're putting through the blades and how much of that is going to be dissolved in the water to meet requirements," Kuljevan said. "It distributes air into the water more efficiently."
The Nashville District operates nine multi-purpose projects in the Cumberland River Basin, which produce about 3.8 billion kilowatt-hours of electricity each year. Sales of this electricity yield about 40 million dollars each year in revenue for the U.S. Treasury.
A Memorandum of Agreement with the Southeastern Power Administration and power customers provides a funding stream to rehabilitate 28 hydroelectric generating units operated by the district. The Water Resources Development Act of 2000, Section 212, authorized the Corps of Engineers to accept and expend a portion of this revenue to perform rehab work on hydropower equipment. Under this provision of the law, funds that would normally be returned to the general fund of the U.S. Treasury are now available to maintain the hydropower generating equipment.
Over the life of the program SEPA looks to direct more than $1.2 billion into the Cumberland River System Hydropower Rehabilitation.
James said that all 28 units were placed into service between 1948 and 1977, and they are far beyond an expected 35-year-design life. The rehab of the three turbine generators located at Center Hill Dam is the start of a 20-year process to rehab all of the turbines, and the laboratory testing is vital to the success of the project, he said.
"We have certain parameters the equipment has to operate inside in terms of power that it produces (such as) flow conditions. They do the model test to verify that the design that they propose will actually perform within (those) parameters," James said.
The Hydropower Rehabilitation Program is about modernizing and increasing the reliability of the equipment, James said. He added that equipment failures cause forced outages, which reduce the production capacity of valuable green energy.
(The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district's website at www.lrn.usace.army.mil, on Facebook at http://www.facebook.com/nashvillecorps and on Twitter at http://www.twitter.com/nashvillecorps.)
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