Departmental Bulletin Paper 逆流保炎燃焼における気体および液体燃料の排気特性に関する研究

廣井, 巧

Emissions in reverse flow flame stabilized (RFFS) combustion were investigated at atmospheric pressure with kerosene to study its applicability for the first stage of a liquid-fueled, staged low emissions gas turbine combustor which is characterized by the reactions of ultra-lean to lean secondary mixtures injected into the burned gas from the lean burn first stage. The fuel was atomized by a pre-filming type twin-fluid atomizer in a co-flowing combustion air flow and the resulting mixture was injected toward the end wall of a tubular RFFS combustor. The droplet size distribution of the sprays by this atomizer were found to depend on the pressure of atomizing air but independent of fuel flow rate or air-liquid mass ratio over the whole range of the fuel and air flow rates in the present study. Therefore, equivalence ratio was able to be varied by adjusting fuel flow rate with maintaining atomization at several fixed levels. The effects of atomization level, air preheating to 373, 473 and 573 K, the positions for mixture injection and gas sampling above the end wall and equivalence ratio on the NOx and CO emissions and combustion efficiency were studied. Global structure of the flames was recorded by direct photography. Similar investigations were conducted with methane by feeding the fuel to the liquid passage of the twin-fluid atomizer to investigate the difference of phases of fuel, gas or liquid. This paper describes comparisons of the emissions characteristics of RFFS combustor with methane and kerosene obtained in the present study and those with homogeneous methane-air mixtures in our previous study. Key Words : RFFS combustion, NOx emissions, a pre-filming type twin-fluid atomizer

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