Distributed Regime and Swirler Effects on Methane and Coke Oven Gas Combustion Characteristics

The present study deals with combustion characteristics of methane and coke oven gas for various swirl numbers in a highly internal recirculative combustor under colorless distributed combustion conditions. In order to achieve that, the fuels have been consumed numerically in the combustor at various oxygen concentrations by using a N2 diluent to reduce oxygen concentration in the air. During the modelings, swirl number has been changed from s=0 to s=1 in an interval of 0.2. In this way, swirler effects on its combustion characteristics have been studied. In order to perform all modelings, the k-ε realizable turbulence model, the PDF/Mixture Fraction combustion model, and P-1 radiation model have been used. The results showed that decrease in oxygen concentration caused a more uniform temperature field in the combustor along with ultra-low NOx emissions. When the oxygen rate was reduced from 21% to 15%, a 9% decrease in the highest temperature reached in the combustion chamber was observed. In addition, a 99% decrease in nitrogen oxide formation was observed. This has been achieved with internal and external (colorless distributed regime) entrainments. In addition to these, it is concluded that the swirler has affected that combustion took place faster mostly because of better air-fuel mixture in the combustor. It has been observed that the air and fuel mixture occurs faster in the swirler effect, which has effects on the flow characteristics in the combustion chamber and has positive effects on recirculation, which can help to obtain conditions close to distributed combustion conditions in general. For 21% oxygen ratio, nitrogen oxide formation could be reduced by approximately 50% by increasing the swirl number from 0 to 1.