The Advantages of Direct Ammonia Injection vs Traditional SCR Systems

At POWERGEN 2025, Paul DiMascio, Chief Engineer at ProEnergy Services, and Jeff Wirt, Director of Catalyst Systems at EnergyLink International, presented a case study of a GE LM6000 selective catalyst reduction (SCR) pilot at Wattbridge Energy’s Braes Bayou facility during their session, Significant Findings from a Breakthrough in Gas Turbine NOx and CO Removal.

To overcome some of the issues with conventional SCR systems, such as cost and complexity, EnergyLink International developed a direct ammonia injection (DAI) system that simplifies NOx and CO removal and reduces the need for certain components, such as vaporization systems.

Assistant editor James Cook spoke with DiMascio to better understand the DAI system and its advantages over traditional SCR systems, how it reduces its footprint by eliminating the need for some components, and how it reduces costs.

DiMascio said: “The primary advantage is because of the idea of moving the injection point forward, we take advantage of the temperature and turbulence of the exhaust stream of the gas turbine to evaporate the water and thoroughly mix the ammonia with the exhaust gases.”

It eliminates the need for certain components because it “more thoroughly mixes the ammonia with the exhaust and yet doesn't require the injection skid that vaporizes the water and ammonia beforehand because it does that automatically,” he said. “So, you remove the skid. In addition, you have an immense grid of piping that covers the entire face of the SCR, and that all goes away because you moved it all the way up to the back end of the engine, and that mixing spreads it out for you. So about three tons of stainless-steel piping and all the labor necessary to install it disappears.”

Check out the full video interview below.