Combustion characteristics of a lean premixed LPG–air combustor

Fuel/air mixing effects in a premixer have been examined to investigate the combustion characteristics, such as the emission of NOx and CO, under simulated lean premixed gas turbine combustor conditions at normal and elevated pressures of up to 3.5 bar with air preheat temperature of 450 K. The results obtained have been compared with a diffusion flame type gas turbine combustor for emission characteristics. The results show that the NOx emission is profoundly affected by the mixing between fuel and air in the combustor. NOx emission is lowered by supplying uniform fuel/air gas mixture to the combustor and the NOx emission reduces with decrease in residence time of the hot gases in the combustor. The NOx emission level of the lean premixed combustor is a strong function of equivalence ratio and the dependency is smaller for a traditional diffusion flame combustor under the examined experimental conditions. Furthermore, the recirculation flow, affected by dome angle of combustor, reduces the high temperature reaction zone or hot spot in the combustor, thus reducing the NOx emission levels.