Written by Scott Schreeg | Power Plants

SVI Dynamics recently completed a stack silencer replacement at a combined cycle power plant in South Carolina. The purpose of the project was to retrofit the HRSG stack silencer during a planned plant outage and improve the durability of the silencer system. The original stack silencer baffle OEM was Sound Technologies, and there were many opportunities to improve the silencer design and durability.

What Type of Silencer Baffle Work Was Needed?

To retrofit the HRSG stack silencer in the combined cycle power plant, SVI Dynamics provided turnkey (EPC) support with in-house resources, including design, engineering, and construction for the project. The construction was supported by Bremco, who is part of the SVI family of companies. The prior year’s inspection during a planned outage gave the project team a clear vision of the scope of the project. On the unit to be worked on, about 1/3 of the existing baffles appeared to be wedged or stuck in the existing silencer supports. Fortunately, the previous inspection provided the team with knowledge about the best removal method to use, considering the excessive weld material on existing guides and the arrangement of the stack damper under the baffle supports.

Project scope highlights included:

  • SVI installed new guides in 18-inch sections starting from the support plate and a 24-inch section at the top baffle.
  • Replacement silencers and mounting components will be of upgraded construction designed by the SVI in-house director of acoustical engineering as follows:
    • Silencer perforated sheet upgraded to 12Ga 409 stainless steel for better corrosion resistance
    • Acoustical fill to be upgraded to 6PCF mineral wool
    • Includes standard drain holes for moisture removal
    • Revised silencer design to eliminate tails and incorporate standard silencer active length with aerodynamic radius at silencer exit. The stack silencer baffles from Sound Technologies utilized a tapered tail as part of the silencer active length. The new design eliminated the tail and replaced it by extending the same thickness as the rest of the silencer baffle. The tapered design was to help improve flow distribution at the silencer exit, but through CFD analysis, this can be easily accomplished with a rounded, aerodynamic edge as on the silencer inlet. This provides the same or better acoustical and aerodynamic performance and is more durable.

What is the Typical Sequence for this Retrofit?

The SVI Dynamics team performed the following steps to replace silencer baffles in the power plant unit:

  • Removed 18 original silencer baffles
  • Staged the new silencer baffles in order of installation
  • Inspected and performed NDE on silencer baffle supports inside the stack
  • Prepared new guides for installation
  • Installed bottom level of silencer baffle supports, middle row of guides, and upper row of guides
  • Installed new silencer baffles in the unit

The silencer baffle replacement project was completed safely and on time within the 15 days outage schedule.

Does Your Power Plant Need a Silencer Baffle Replacement Like This?

At SVI Dynamics, we provide industrial noise solutions for power plant applications, including silencer baffle replacement. Our team has extensive experience in industrial noise control and is a leading turnkey supplier for all of your gas path support. Our engineers design innovative solutions to help you meet all your acoustic project goals. If your plant’s acoustical system needs a professional inspection, repair, or replacement, contact SVI Dynamics today to schedule an inspection and comprehensive repair recommendations and installation.