Study on Reduced Chemical Mechanisms of Ammonia/Methane Combustion under Gas Turbine Conditions

Abstract

As an alternative fuel and hydrogen carrier, ammonia is believed to have good potential for future power generation. To explore the feasibility of co-firing ammonia with methane, studies involving robust numerical analyses with detailed chemistry are required to progress toward industrial implementation. Therefore, the objective of this study is to determine a reduced mechanism for simulation studies of ammonia/methane combustion in practical gas turbine combustor conditions. First, five different-sized reduced mechanisms of the well-known Konnov’s mechanism were compared. The reduced mechanisms were tested for ignition delay time validation (zero dimensional) using ammonia/methane mixtures at high-pressure conditions relevant to gas turbine devices. Furthermore, the combustion products of ammonia/methane premixed laminar flames (one dimensional) were validated with the results from the full Konnov’s mechanism. Finally, computational fluid dynamics simulations of a turbulent flame (two dimensional) with all of the reduced mechanisms were performed under high-temperature and high-pressure conditions representative of industrial systems. Results show that several of the reduced mechanisms utilized performed reasonably well in combustion simulation studies under gas turbine conditions. Hence, a reaction mechanism with 48 species and 500 elementary reactions is recommended for future studies.

Preliminary study on lean premixed combustion of ammonia-hydrogen for swirling gas turbine combustors

“…The analysis was carried out using 5 different reaction mechanisms, selecting those that show the most promising results for the study of ammonia/hydrogen gas turbines as done by Xiao et al [29]. A redu ed odel of Ko o 's mechanism [23], Tia 's [30], Mathieu's [31], Klippe stei 's [32], a d Miller's [33] were used for the study, Figure 2. The results demonstrate that the flame speed of a 50:50 ammonia/hydrogen blend is close to that produced by methane [34][35] under lean conditions espe ially usi g Tia 's odel.…”

“…It was found that NOx and CO emissions were considerably low at high equivalence ratios >1.10, identifying a region of chemically reactive balance between methane and ammonia combustion. Xiao et al [23] have also assessed the potential of using ammonia/methane blends for power generation. Using the Konnov reaction mechanism, a 2D numerical study was undertaken to determine the characteristics of methane/ammonia blends and their combustion characteristics.…”

Computation of partial molar properties using continuous fractional component Monte Carlo

“…The reason to select this mixture as a realistic case study is that ammonia is a useful chemical commodity and has received lots of attention both in academia and industry [45][46][47][48][49][50][51]. It is also a promising alternative medium for energy storage and transportation [52][53][54][55]. Industrial ammonia synthesis is carried out using the Haber-Bosch process with heterogeneous iron or ruthenium catalysts at high temperatures (623-873 K) and at a pressure range of 20-40 MPa [56][57][58].…”

Modeling Combustion of Ammonia/Hydrogen Fuel Blends under Gas Turbine Conditions

“…These kinetic models have proven reasonable accuracy for ammonia/hydrogen combustion under certain laboratory conditions. 43−47 However, due to the lack of a comprehensive study and experimental verification, 29,48 the applicability of the mechanisms for practical combustion of ammonia-based fuels still needs to be developed and improved, particularly for industrially relevant conditions.…”