EFFECT OF H_2 ADDITION ON SOOT FORMATION IN FUEL-RICH CH_4/AIR TURBULENT DIFFUSION FLAMES

摘要

In this study, the difference of temperature and the component of chemical species on soot formation in CH_4/air fuel-rich diffusion flames were investigated. Furthermore, for decreasing soot formation in fuel-rich diffusion flames, we added H_2 in CH_4, investigated the property of combustion, and compared with methane/air fuel-rich flames. We have paid much attention to the influence of the equivalence ratio of methane(+H_2)/air, the swirl strength of combustion air and the concentration of C_2H_2 on the soot formation. The experimental combustor for CH_4(+H_2)/air combustion was designed, and the soot resulting from the exhaust gas collected with a silica filter and its weight was measured. The microstructure of the soot particles were analyzed with a Scanning Electron Microscopy (SEM). The temperature profiles in the combustor were measured by thermocouples, and the concentrations of the species O_2, CO_2, H_2, CH_4 and C_2H_2 were determined by a TCD (thermal conductivity detector) gas chromatograph (GC) and FID (flame ionization detector) GC. The soot yields diminished with increasing swirl strength and the C_2H_2 concentration. When H_2 was added to the fuel, combustion was promoted and C_2H_2 concentration in the exhaust gas was diminished. But using strong swirl, fuel and air were mixed quickly, the effect of H_2 addition was decreased.