Assessment and optimization of combustion efficiency and emissions of industrial gases burner blended with hydrogen and ammonia gaseous fuel

This study investigates the impact of hydrogen, methane and ammonia fuel mixtures on the combustion characteristics of a typical conventional burner using numerical analysis. Six fuel mixtures with varying proportions of hydrogen, methane, and ammonia were examined in this study. Throughout the entire simulations the hydrogen content was fixed at 50 % by volume. Computational fluid dynamic analysis was carried out to analyze the effect of ammonia gas composition on combustion temperature, flame structure, and emissions of H2O, carbon monoxide (CO) and carbon dioxide (CO2), and Nitrogen oxides (NOx). Simulations were performed using ANSYS Fluent V22. Specifically, a steady-state, two-dimensional numerical model was employed via pressure-based solver, the SST k-omega turbulence model for turbulence, and a non-premixed combustion model to capture detailed combustion chemistry and turbulent mixing effects. Peak combustion temperature reductions of up to 110 K corresponded directly with reduced thermal NOx formation as ammonia content increased. With higher ammonia content, more uniform temperature distributions, and reduced CO2 emissions within the chamber. However, increasing ammonia concentrations can also result in increased H2O formation due to ammonia decomposition and high NOx emission owing to its high nitrogen content in the ammonia. The formation of water vapor increases with increase in the ammonia content, while CO and carbon dioxide CO2 emissions decreases. NOx concentrations was at maximum around the upper part of the domain due to the high combustion temperature. After considering all the factors, it was observed that the fuel combinations with higher ammonia content and lower methane content resulted in significantly lower CO2 emission but high NOx emission.