Supplementary “Duct” Firing for Combined Cycle Power Plants & How it Compares to TIAC

While both Supplementary or Duct Firing and Turbine Inlet Air Chilling (TIAC) are solutions to offset the megawatt output degradation of gas turbines when ambient temperatures rise, the two technologies take very different approaches.  With TIAC, the combustion gas turbine inlet air is chilled. In the case of duct firing, injection of fuel is utilized to increase the temperature and mass flow rate of the exhaust gases.

Rather than competing, the two technologies – duct firing and turbine inlet cooling – can actually complement each other when used correctly.

For maximum power output, power plant owners can utilizing the reliable power augmentation provided by TIAC, and balance the requirements with duct firing.  This scenario allows them to produce the required power at the lowest possible heat rate.

However, the combination of TIAC with Duct Firing is rare – most owners choose one solution over the other. Let’s look at how Duct Firing works.