Oxygen-Enriched Premixed And Fuel Staged Combustion Influence On Nitrogen Oxide

Though the burning of fossil fuels provides source of energy and power, it also products a large number of harmful substances, which severely damage the natural environment and negatively impact on the economy. Natural gas has gradually called widely attention because of its abundant reservation and low carbon releasing. All these make it become one of the fastest-growing energy resources.This study conducts a numerical simulations on diffusion flames, lean premixed flames, partially premixed methane/air counter-flow flames and oxygen-enriched premixed and fuel staged combustion flames by simplifying the physical geometry based on the platform of FLUENT software and then, analyses the effects of the oxygen concentration, the equivalence ratio and fuel classification ratio on flame structure, reaction mechanism and pollutant emissions. The study reveals that, not only can the combustion efficiency be effectively improved, but also the components of pollutants can be changed environment-friendly by adjusting the concentration distribution of fuel/ oxidant spatial modulation through the process of oxygen-enriched premixed and fuel staged combustion.A comparative analysis was done on the following conditions which include equivalence ratio of the overall Φ=0.6,0.7,0.8,0.9,1.0,1.1,1.2, the fuel staged proportion is 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and oxygen concentration =0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95. The optimum condition is Φ=0.9 for the equivalence ratio of the overall and the fuel staged proportion is 0.4. Influence of oxygen concentration on NO formation is the most obvious, the outlet of combustion chamber concentration increases with the increasing of oxygen concentration in. oxygen concentration is 60%, showed a maximum value, then decreases with increasing the concentration of oxygen. The thermal NO emissions accounted for a large proportion, when the oxygen concentration is greater than 40%, the thermal NO of total NO emissions 99%.