Numerical Study of Cocombustion Characteristics of Ammonia and Coke Oven Gas

This study investigates the combustion characteristics of hydrogen, methane, and coke oven gas (COG) blended with ammonia (NH₃) using one-dimensional simulations. The laminar burning velocity (LBV), adiabatic flame temperature, and nitrogen oxide (NO_x) emissions were analyzed across different NH₃ blending ratios (0%–100%). Hydrogen had the highest burning velocity, dropping sharply with NH₃, while methane’s decrease was gradual. COG showed intermediate behavior, resembling hydrogen. The addition of NH₃ reduced the adiabatic flame temperature in all mixtures, with COG/NH₃/air exhibiting a trend between H₂/NH₃ and CH₄/NH₃. Flame thickness increased with NH₃ content, with COG following trends similar to those of H₂/NH₃/air combustion. NO_x emissions were initially low for all fuels, but increased significantly with NH₃ addition, peaking at 25% NH₃ for H₂ and COG, and 50% NH₃ for CH₄, after which emissions declined owing to the weakening of the HNO pathway. COG/NH₃ combustion characteristics align closely with H₂/NH₃ but trend toward CH₄/NH₃ as NH₃ content rises. The study introduces a method to predict COG/NH₃/air combustion characteristics by fitting the combustion data of H₂/NH₃/air and CH₄/NH₃/air. This method provides accurate predictions of LBV, flame temperature, and nitric oxide (NO) emissions. Methane’s influence is most significant on flame temperature, followed by NO emissions and LBV.