Thermoacoustic instability has been reported in various combustion systems including industrial combustors (heaters, boilers, etc.), propulsion systems (rockets, afterburners) and gas turbine combustors. Thermoacoustic instability can be addressed by adding acoustic damping to the combustion environment. In larger industrial applications, tonal acoustic damping solutions such as quarter wave tubes and/or Helmholtz resonators or even active acoustic damping solutions can be used to quiet this instability.
This paper discusses the numerical investigation of mitigating the 30 Hz thermoacoustic instability in a fire-tube 600 horsepower steam boiler. By conducting finite element analysis of the acoustics of the combustion chamber and all the fire-tubes, the 30 Hz mode sympathizing with the heat release dynamics of the chamber is identified. Subsequently, a number of tuned acoustic absorption solutions are experimented with, numerically (on the finite element model of the boiler’s acoustics), and the most suitable (in terms of effectiveness and ease of implementation) candidate solution is identified. Currently, work is underway to implement this solution on the boiler.