There are multiple sources of noise within combined cycle gas power plants (CCPP) that have to be addressed so they stay under the maximum noise level that a plant is permitted to have. In CCPPs, like simple cycle power plants, you will find silencers in the exhaust. These silencers are called parallel baffles, absorptive baffles, and sometimes, splitters. They are silencer panels that are inserted into the gas path, parallel to the flow. The exhaust system ductwork of the system is used to direct the exhaust of gas turbines through a silencer section and stack to the CCPP’s heat recovery steam generator (HRSG), providing added efficiency, meeting emissions requirements, and reducing noise.

It’s not as common to have a significant amount of silencing in a CCPP in the HRSG because the noise that’s coming through the system is attenuated a lot by the actual boiler tube rows. This reduces the need for silencing when compared to a simple cycle that doesn’t have an HRSG to muffle the noise. Nonetheless, large combined cycle plants have big, noisy turbines so there is still usually the need for some sort of silencer to ensure compliance with noise regulations.

Exhaust silencers, like other CCPP parts and components, do wear out. When they do, it’s critical for power plants to have a reliable, experienced industrial repair source to mitigate the issue.

What Causes Gas Turbine Exhaust Silencers to Fail?

Just like the muffler on your car, gas turbine exhaust silencers will wear out over time. There are numerous ways that they can become damaged or worn enough that they are no longer effective, and they present noise issues, as well as potentially hazardous incidents for site personnel and surrounding equipment.

Gas turbine exhaust silencers may wear gradually or fail due to damage that occurs all at once. The internal fill materials typically degrade slowly, while in other situations, such as the metal frame cracking, or the supports failing, there can be a sudden failure that needs attention right away.

Because the internal sound absorption material is porous by design (to effectively absorb sounds), they are vulnerable to the extreme hear and forceful gas turbine exhaust velocities. This caused degradation over time. That’s why it’s imperative that gas turbine exhaust silencers are carefully and expertly designed thermally and structurally. Various factors must be considered to properly design silencers, including materials, design techniques, and how they are fabricated. In many cases, silencers have to be replaced due to inadequate thermal or structural design. Additionally, when stack silencers do fail, they may expel debris from the stack, which may endanger people and equipment in the surrounding area.

Mitigating silencer problems to avoid unplanned outages requires thorough inspections that are scheduled regularly so that a baseline of current conditions can be established, and a timeline of needed repairs can be created. Then, maintenance, repairs, or replacements can be scheduled to be performed during planned plant outages, saving time and money for your power plant.

SVI is Your Provider for Noise Assessments and Mitigation Solutions

At SVI DYNAMICS, a division of SVI INDUSTRIAL, we have worked with power plants to repair, replace, upgrade, and retrofit HRSG stack silencers to provide industrial noise control solutions. We are a leading manufacturer of engineered gas path solutions including inlet and exhaust systems and silencers for gas turbines. We provide noise assessments for power generation plants, using our extensive experience in industrial noise control and exhaust silencer manufacturing to be a leading turnkey source for gas path support. We use in-house engineering to design innovative solutions to meet your acoustic, structural, thermal, and aerodynamic project objectives.  

Whether you are experiencing acoustic or silencer failures, have a planned outage coming up and need a thorough inspection, or have a need for retrofitting to upgrade silencers for better performance, SVI can help. Let us be your turnkey source for gas path support.