The role of CO2 on oxy-colorless distributed combustion

Oxy-fuel combustion is one of the routes to have carbon dioxide as the main component of the combustion products stream, enabling carbon capture and sequestration. However, oxy-fuel combustion presents challenges in terms of higher temperatures and flame speed, dictating the need for dilution using entrainment of non-reactive diluents. This need for dilution presents opportunities for developing oxy-fuel combustion using distributed combustion technique. Distributed combustion has been investigated in different configurations and geometries, demonstrating near zero emissions, uniform thermal field and much reduced combustion noise. Key element to achieve distributed combustion is mixture preparation with controlled entrainment of hot reactive species from within the combustor and their subsequent mixing with the fresh reactants to form reduced oxygen concentration-high temperature oxidizer to achieve distributed combustion in the combustor. This necessary entrainment can be beneficial in oxy-fuel combustion as it satisfies the need to utilize CO2 back into the reaction zone for dilution. In this paper, distributed combustion was investigated with focus on oxy-methane combustion. Experiments were performed on a swirl flame combustor with oxygen concentration ranging between 40 and 21% of the oxidizer mixture. Results showed the possibility of achieving distributed combustion using oxy-fuel combustion. This is demonstrated through OH∗ chemiluminescence wherein the reaction zone extended to cover larger portion of the combustor as opposed to that of a traditional swirl flame. Emissions measurements showed the elimination of NO emission with low CO emissions, demonstrating the benefits of incorporating distributed combustion concept using oxy-fuel combustion for carbon capture with the product stream containing mostly CO2.