Reduced Chemical Mechanisms for Ammonia/Methane Co-firing for Gas Turbine Applications

Energy storage is one of the major challenges facing the world towards its challenging 2050 climate-change targets. A potential enabler of a low-carbon economy is the energy vector hydrogen. However, issues associated with hydrogen have led to consider other molecules such as ammonia as a potential candidate for chemical storage. Apart from its relatively high stability under atmospheric temperature, ammonia has the added attraction that it can also be sold on international markets or be used for power generation, making it a very versatile and hence attractive commodity. To explore the feasibility of co-firing ammonia with other fuels, i.e. methane, detailed numerical analyses and flame chemistry are required, usually at very high computational cost. Therefore, this study intends to determine a reduced mechanism for ammonia/methane combustion for practical gas turbine combustor conditions. Five reduced mechanisms of the well-known Konnov's mechanism were compared. Ignition delay time validations (0D) under industrially relevant conditions were used for correlation purposes. Combustion products of ammonia/methane premixed laminar flames (1D) were also validated with results from the full Konnov's mechanism. Finally, CFD simulations of a turbulent flame (2D) including reduced mechanisms were performed at representative industrial conditions. Results showed a reduced reaction mechanism of 48 Species and 500 elementary reactions can provide good results for further analyses.