Gleason Unit 3 Silencer Still ‘Right Thing to Do’ for Local Community

After six months in reserved shutdown, Unit 3 at TVA’s Gleason Combustion Turbine Plant will soon be back online after the planned spring outage, complete with a brand new exhaust stack silencer for continued noise reduction.

“The stack silencer acts as a muffler on our exhaust stack for sound reduction,” says Steven Trull, Gleason site manager.

Before TVA purchased the Gleason site in 2006, the surrounding community complained of low vibrations during times of operation, which was identified to be caused by the exhaust stack. After an evaluation, TVA installed a silencer to reduce the noise.

“TVA is both a steward to the environment and the communities in which we live and serve,” says Trull. “Installing a silencer was the right thing to do then, and updating the unit with a new silencer after the old one began to deteriorate is the right thing to do now.”

The previous Unit 3 silencer became a safety concern in October 2020 when foreign material ejected from the stack due to deterioration. The unit was placed in reserved shutdown until the planned spring outage, where the silencer install was critical path.

“We replaced the inner stack silencer baffles with an improved design to further improve acoustic performance,” says John Clapacs, regional outage manager. “Removing and replacing the upper stack – which weighs approximately 32 tons – requires an extensive amount of rigging and structural modification. The team has successfully performed this work with no safety, HU or environmental incidents.”

“We removed the round-top section of the stack to access the silencers in the area below. The new silencers have more space between them in the square or rectangular pathways for the gas to move through,” says Tate Roby, outage specialist. “This reduces the velocity of the gas emitted to improve the silencer’s durability and keeps the asset running at a quieter level.”

The outage is scheduled to be complete mid-April, which also included balance of plant-related work such as checkups on instrumentation, calibrations and filter changeouts.

“With a capacity of 185 megawatts per unit, Gleason’s three units are important to meet the Valley’s power demand,” says Trull. “After the outage, we’ll bring Unit 3 back online, which will be a huge benefit as we move into the hot summer months.”