59744 - Combustion of Hydrogen-Methane-Air Mixtures in a Generic Triple Swirl Burner: Numerical Studies 

Ever-increasing energy demand, limited non-renewable resources, requirement for increased operational flexibility, and the need for reduction of pollutant emissions are the critical factors that drives the development of next generation fuel flexible gas turbine combustors. The use of hydrogen and hydrogen-based fuels such as syngas and ammonia potentially reduce carbon and NOx emissions. However, high temperatures and flame speeds associated with hydrogen might increase the NOx emissions. Diluting the fuel-air mixtures with steam presents a promising approach for NOx control. Steam dilution inhibits the formation of NOx and also allows for operating on hydrogen-rich fuels, and even pure hydrogen. The challenge in the implementation of this technology is the combustor design, which must provide a stable combustion process at high hydrogen content and ultra-wet conditions. As lean premixed swirl stabilized combustion system is the most viable option for achieving low NOx in gas turbine industry, therefore, in the present work, we investigate the flow field and combustion characteristics of a generic triple swirl burner running on premixed methane-air with hydrogen and steam injection.

The investigated burner consists of three co-axial co-rotating swirling passages: outer radial swirler stage, and two inner concentric axial swirler stages. Reynolds Averaged Navier-Stokes (RANS) simulation approach has been utilized here for flow description within the burner and inside the combustor. We first present the flow fields from isothermal and lean premixed methane-air reactive simulations based on the characterization of velocity profiles, streamwise and azimuthal shear layers, temperature fields and NOx emission profiles. We present the validation of isothermal RANS profiles through experimental results. We then investigate the combustion flow fields, flame behaviour and its stability for hydrogen enriched methane-air mixtures as a function of hydrogen content. We also investigate the possibility of steam diluted combustion for methane-hydrogen blends and present comparison of flame shapes, temperature estimations and NOx emissions.