A work crew installed a 249-ton hydropower rotor today at Center Hill Dam, culminating weeks of safety preparations to lift and maneuver the heavy load into position to generate hydroelectricity.
With the safe installation of the rotor, the U.S. Army Corps of Engineers Nashville District and contractor Voith Hydro expect to finish rehabilitation of hydropower unit two in mid-July once its final assembly and load testing are complete.
Jerry Lee, project engineer for the Center Hill Turbine Generator Rehabilitation Project, gave props to Steve Rodriguez, the crane operator responsible for moving the rotor from the power plant’s gallery and placing it into the hydropower unit.
“This is not something we do every day. This is the largest component in the turbine generator. It’s a capacity lift for this crane,” Lee said.
Lee explained that installing the rotor is very challenging because there’s only a nine-sixteenth inch gap between the rotor and the stator, which is a very tight fit.
“It’s got to go back in precisely. The parts that we’ve rebuilt are very expensive. We’ve spent millions of dollars here and you don’t want to bump them or damage any of the stuff going back in,” Lee stressed.
Because of the heavy load and the precise operation, the Corps of Engineers and the contractor made safety the number one priority throughout the lift and install.
Martin Parker, site manager for Voith Hydro, said the team definitely focused on the safety requirements and described the installation as “tricky” because of the tight fit. Installing the rotor into the stator without bumping or rubbing is important to prevent damaging the components, he said.
“The rotor went in nice and even and went down with a good air gap – didn’t have any problems,” Parker said. “Now they’re just bolting it up and it’s looking really good.”
Since the project began in September 2015, the contractor has rebuilt the generator’s rotor, overhauled the shaft, and replaced the stator, stator coils, wicket gates and turbine, which now features an aeration capability designed to add oxygen to the water to benefit the aquatic life downstream of the dam.
“Now we put the upper bracket in place, we do our alignment checks, and hopefully we should have it ready for wet testing by the second week of July, ready to run,” Parker said.
The hydropower unit at Center Hill Dam is the first of 28 units at nine projects that will be rehabilitated. The Nashville District awarded a $47.25 million contract to Voith Hydro in June 2014 to rehabilitate three Center Hill Dam hydropower units. The contractor mobilized to the dam in July 2015 and began the rehabilitation of unit two. Unit one will then be rehabilitated followed by unit three.
Center Hill Dam is located on the Caney Fork River and contributes to the electrical power supply of the area through the generation of clean, safe and efficient hydroelectric power. A single hydropower unit at this location supplies enough electricity to power 12,000 homes, which reduces the cost of electricity during peak periods of the daytime. All three hydropower units can supply the needs of an average city of 125,000 people.
The Nashville District operates nine multi-purpose projects in the Cumberland River Basin. Electricity is marketed by the Southeastern Power Administration and then sold to the Tennessee Valley Authority and other preference customers in the region.
The Water Resources Development Act of 2000, Section 212, authorized the Corps to accept and expend funds from power preference customers 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 used 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.