New Gas Turbine Combustor for Record Low NOx Emissions Developed

Tokyo, September 27, 2011 — Kawasaki Heavy Industries, Ltd. announced today that it has brought NOx emissions to a new low. The guaranteed maximum NOx emissions level of the dry low emissions (DLE) combustion system used in its 7 MW-class M7A-03 gas turbines has been reduced from 15 ppm to 9.9 ppm (converted at 15% O2). Kawasaki is the first in the world to achieve a single-digit guaranteed maximum NOx emissions level in DLE combustion systems of this class.

DLE combustors employ a premixed combustion method to generate the high-temperature gas needed for high-speed turbine operation. While NOx is generated during the gas turbine fuel combustion process, the amount produced largely depends on the combustion temperature. The premixed combustion technique minimizes combustion temperature without the use of injected water or steam by premixing the fuel with air to significantly reduce NOx emissions. This feature has made DLE combustors the most widely used combustion systems employed in gas turbines.

The big problem with premixed combustion, especially when used to lower NOx emissions, has always been stability. Now Kawasaki has overcome this perennial technological stumbling block to lowering DLE combustor NOx emissions. The driving force behind the successful development of this new DLE system, boasting outstanding combustion stability, is an innovative proprietary combustion mechanism. Kawasaki’s combustion mechanism features a multistage burner process employing a pilot burner as well as main and supplemental burners. This latest technological breakthrough in lowering NOx emissions is built on a solid foundation of ongoing DLE combustor R&D. Kawasaki has leveraged the technological expertise it has gained over the years to replace all its burners with low-emission premix burners.

Since stationary gas turbines emit NOx gasses that result in photochemical smog and acid rain, they are subject to strict regulations across the globe. While NOx emissions standards are set at 25 ppm or below in most countries, an increasing number of local governments in the U.S. and Europe, where public awareness about air quality is high, are implementing even stricter NOx emissions standards that require a maximum emissions level of 15 ppm, or even 10 ppm in some areas.

To meet these increasingly tougher NOx emissions standards, Kawasaki is working to enhance overall gas turbine efficiency and develop innovative combustion technologies that will lower gas turbine emissions. Kawasaki is looking at new ways to put technology to work for the global environment with more efficient products that leave a smaller environmental footprint.

Gas Turbine Combustor Design