Researchers from the University of Maryland, V. Viswamithra, M. Gurunadhan, and S. Menon, have been exploring ways to make ammonia a more viable fuel option for power generation in gas turbines, a move that could significantly reduce greenhouse gas emissions. Their work, published in the journal Combustion and Flame, focuses on overcoming the challenges of ammonia combustion and minimizing harmful emissions.
Ammonia is a carbon-free fuel, making it an attractive alternative for power generation. However, its use in gas turbines comes with challenges, such as reduced flame speed and reactivity. To address these issues, the researchers investigated two strategies to widen the stability limits of swirl combustors operating on premixed methane-ammonia-air mixtures.
The first strategy involved a distributed fuel injection approach using a novel micro fuel injection swirler. This method helped prevent flashback, a phenomenon where the flame travels upstream into the fuel supply, which can cause damage to the combustor. The second strategy involved preheating the inlet air to increase flame stability and delay blow-off, where the flame extinguishes due to low fuel-air ratios.
The researchers conducted experiments and reactor network simulations to evaluate the effectiveness of these strategies. They found that the distributed fuel injection strategy significantly expanded the stability limits of the combustor. Inlet air preheating provided additional expansion of these limits but increased NOx production, which is undesirable from an emissions standpoint.
The study also analyzed the underlying reaction pathways leading to NOx production. It was found that NOx emissions were significantly lower for rich fuel-air mixtures primarily due to the effect of NHi reaction pathways responsible for NO consumption.
This research is a step towards making ammonia a more practical fuel option for the energy industry. By improving the stability and reducing emissions of ammonia combustion, it could become a more viable alternative to traditional fossil fuels in power generation. The findings could help in the design of more efficient and cleaner gas turbines, contributing to the global effort to reduce greenhouse gas emissions.
This article is based on research available at arXiv.