Most HRSGs employ floating liner systems that allows for thermal expansion on the internal liner surface while providing the necessary insulation to provide a cool external casing.
Failures in the casing and liner system can not only cause major hotspots and degradation of the casing system itself but can also lead to catastrophic insulation loss. This loose insulation can then foul coil fins or clog the downstream catalyst systems. These catalyst systems are critical to emissions control and can be compromised by such damage. The backpressure caused by such fouling can also lead to forced outages due to combustion turbine trips associated with high back pressure. In addition to these problems, a high enough back pressure can cause structural issues with the frame systems that hold the catalyst blocks in place. In the most severe circumstances, they can be dislodged and damage downstream tube bundles. As such, it is critical to maintain these liner systems and employ the proper combination of design features and materials to ensure long lasting and reliable HRSG functionality.
Plants upgrade combustion turbines, burners and other equipment. Often overlooked, but of critical importance, is the casing and liner system. Failures in the liner systems can be caused by not properly considering the changing design conditions associated with such upgrades as. These upgrades often contribute to localized overheating, excessive vibration, high gas velocities, exhaust turbulence, creep damage or corrosion. Nooter/Eriksen offers several options to protect the casing and liner systems from the rigors of new operating conditions related to CT or burner upgrades.