Optimization of combustion and emission characteristics of coke oven gas doped ammonia/air mixture by colorless distributed combustion (CDC) technology

Abstract

This study’s motivation is to reduce the NO emissions of ammonia/air mixture, whose NO emissions are promoted by coke oven gas (COG) addition, by implementing the CDC technology. Within this scope, the effects of the CDC technology on the termal and emission characteristics of the COG/ammonia/air mixture were numerically investigated under the non-premixed combustion conditions. In order to perform a detailed investigation, the simulations were performed for the different operating conditions where the oxidizer inlet temperature (300 K or 600 K) and diluent type (N2 and CO2) were varied. Under the distributed combustion regimes, declines in flame thicknesses and temperatures were observed and this provided more uniform temperature fields. Besides, the flame blowout limits varied and it observed 20% and 18.5% under CO2 and N2 dilutions, respectively for the 300 K inlet temperature. Increasing the inlet temperature provided wider blowout limits up to O2 concentration of 16%. Reduction levels up to 45.83% in NO emissions were achieved compared to conventional combustion. This showed that CDC technology is a promising way to suppress the primary NO formation mechanisms of the mixture. Because the preheating promoted the reactions rates the maximum reduction in NO emissions was 29%. Therefore, it can be said that CDC method should be implemented to the mixture when the reactants are at room temperature and the diluent is N2 to obtain the most proper combustion and emission outcomes.

Keywords

• Ammonia combustion
• Pollutant reduction
• Syngas
• Fuel-NO
• Swirling flows

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