Release Date: December 15, 2016
DOE-Supported Research Team Demonstrates Combustor Approaches to Slash Emissions from Advanced Turbines
In a project sponsored by the U.S. Department of Energy’s National Energy Technology Laboratory (NETL), researchers at the Georgia Institute of Technology have shown that major reductions in emissions of nitrogen oxide (NOx) are possible when new combustor design concepts are applied to advanced gas turbines. Using a novel computational tool, the research team was able to rapidly screen more than 20,000 design variations, providing insight into optimizing high-temperature combustor performance while generating the lowest possible NOx emissions.
Current combustion technology is unable to meet emissions requirements at very high temperatures without using expensive post-combustion processes that reduce energy efficiency. Georgia Tech’s research demonstrated that it may be possible to use the computational tool to design future gas turbines that can operate at turbine inlet temperatures in excess of 3,100 °F with an unprecedented level of performance while slashing NOx emissions by 80–90 percent compared to conventional designs.
Funded through the Energy Department’s University Turbine Systems Research (UTSR) Program, the Georgia Tech project supports the program’s mission to develop and transition advanced turbines and turbine-based systems that will operate cleanly and efficiently, including fuel-flexible systems. The research team’s goal is to enable significant gains in energy efficiency by applying new turbine combustor designs to power plants operating on natural gas, coal-derived syngas, or coal-derived high-hydrogen-content fuels.
According to Drs. Tim Lieuwen and Jerry Seitzman, principal investigators for the project, a key question facing researchers is what theoretical minimum NOx levels are achievable as combustion temperatures are raised to increase energy efficiency. The energy industry has suspected that theoretical minimums are much lower than previously thought. The key contribution of this work has been to identify these minimum levels.
While the Georgia Tech team is quick to caution that achieving these theoretical minimums will require significant technology developments, the encouraging results obtained to date support the need for continued research, given the significant benefits that could be achieved with new gas turbine designs, including possibilities for incorporating new manufacturing techniques, such as 3D printing, for advanced fuel injectors, nozzles, and other gas turbine components.
Using the new tool, the research team is also able to explore what happens to NOx and carbon monoxide emissions when small, undesirable disturbances in temperature, mixing, and other parameters occur in localized spots within the combustor. Thus, the new tool may help in advancing energy efficient, low-emission turbine combustor technology in a faster, more cost-effective manner—ultimately reducing technology development time.
Today’s modern industrial and utility-scale gas turbines can achieve more than 61 percent net energy efficiencies (in combined cycles) while emitting less than 15 parts per million NOx emissions. By applying the new computational tool to advanced turbine design applications, the research team has a long-term vision of identifying combustion design modifications that will allow for turbine operation at even higher temperatures, resulting in 65 percent or greater energy efficiencies with low NOx emissions.