Numerical Simulation of Premixed Ammonia/Methane/Air blends in a Swirl-Stabilized Gas Turbine Combustor

Research in the area of zero-carbon energy resources is gaining rapid momentum with the aim to cut down carbon emissions completely within the next few decades. There are a number of zero-carbon energy resources and Ammonia seems to be a promising candidate among them that definitely needs more research and understanding for implementation to industrial operating scales. In this regard, the present work attempts to numerically study various volume % of Ammonia and Methane as a premixed blend with application to gas turbine power generation. The computational domain used in the numerical simulation closely mimicked the actual atmospheric pressure annular combustor rig present in the lab that houses an industrial swirler and has the provision for a pilot flame for flame stabilization. Two different cases were studied: one with no cooling air injection and the other with cooling air injected at the downstream section of the combustor at equivalence ratios from 0.65 to 1.1. The entire 3-D simulation was done using CONVERGE CFD software where the premixed flame was modeled using SAGE detailed chemical kinetics solver, and turbulence was modeled using the RANS RNG k-ε technique. The model was validated with a previously published work in the literature and a current experimental work. Flame stabilization, carbon and NOX emissions were qualitatively as well as quantitatively studied at Reynolds number=50000 under steady state and adiabatic conditions. Analysis using ANSYS Chemkin was performed to complement the numerical findings of CONVERGE. Results showed drastic reduction in NOX emissions by more than 50 % with cooling air injection, along with reduced NOX emission values at lean and rich equivalence ratio conditions for both with and without cooling air cases. A numerically stabilized flame and realistic temperature distribution was observed for all cases except for cases with greater than 90 % Ammonia and at equivalence ratio greater than 1.05