DLE (Dry Low Emission) techniques are widely used today to reduce the harmful NOx emissions associated with high combustion temperatures. In many DLE systems the fuel and air are pre-mixed which effectively keep the flame temperature as low as possible, ideally equal to the turbine inlet temperature. By using pre-mixing stability issues such as flash back and combustion driven dynamics may occur. Operating the engine with hydrogen diluted natural gas will decrease the flash back limits of the system due to the high diffusivity and highly reactive nature of hydrogen. In this study the stability effects of hydrogen diluted into methane in the Siemens SGT-800 combustor is studied. The SGT-800 combustor is an annular combustor where the flame is stabilized using a swirl burner combined with a sudden expansion combustor. The expansion gives rise to a vortex break down where the flame stabilizes in the local low speed zones. Here a single burner sector is studied using the flow solver Siemens PLM software STAR-CCM+. The turbulence is simulated through the use of LES (Large Eddy Simulation) where the largest energy carrying flow scales are resolved and only the smaller scales are modelled. The chemistry is coupled to the turbulent flow simulation by the use of FGM (Flamelet Generated Manifolds) which are integrated using presumed probability density functions. The FGM approach assumes that the local flame structure is laminar and that all species across a flame can be related to a set of control variables. The control variables in this case are the heat loss, the mixture fraction and its variance and a reaction progress variable. In this paper two effects are studied, first the transition from an atmospheric flame to a pressurized flame and second the effect of hydrogen enrichment. The flame shape and position are mainly affected by the transition from atmospheric to high pressure, where the power density increases by almost a factor of 20. The flame is moving further upstream closer to the burner in all pressurized cases. The hydrogen enrichment plays a strong role in how the combustion driven dynamics is coupling with the acoustics of the rig. The high pressure pure methane case show a strong pressure peak whereas the hydrogen enriched case dampens that peak and distributes the energy to other frequencies. This work shows that high fidelity CFD is capable of capturing complex flow and flame interactions such as thermoacoustic instabilities in industrial scale systems.
LES of Hydrogen Enriched Methane/Air Combustion in the SGT-800 Burner at Real Engine Conditions
- Views Icon Views
- Share Icon Share
- Search Site
Moëll, D, Lörstad, D, & Bai, X. "LES of Hydrogen Enriched Methane/Air Combustion in the SGT-800 Burner at Real Engine Conditions." Proceedings of the ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels, and Emissions. Oslo, Norway. June 11–15, 2018. V04BT04A023. ASME. https://doi.org/10.1115/GT2018-76434
Download citation file: