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Advanced class GTs pose special challenges for NOx and CO catalyst system design

| July 28th, 2022

The state-of-the-art gas turbines (GTs), such as the H-class and J-class machines, are designed to maximize fuel-to-electricity efficiency, achieving and even exceeding 60% in combined-cycle mode. Already, there are an impressive number of these machines in the field; one supplier listed 80+ H-class GTs operating, in commissioning, being installed, or on order.

This achievement is accomplished through increased firing temperatures, upgraded combustion staging, and advanced metallurgy. The tradeoff to higher temperature, of course, is increased thermal-NOx formation. Dan Ott, president, Environex Inc told the editors that the burden of turbine-exit NOx emissions ends up on the SCR system, at least to achieve the same stack emissions as specified for F-class sites.