Premixing Combustion of Fuel Sprays by the Cyclone-Jet Combustor and NO_x Reduction

Abstract

As a means for a stable premixed combustion, there is a so-called cyclone combustor, which consists of a cylindrical chamber and fuel nozzles installed tangentially on the side wall. In this combustor an extremely stable flame can be obtained in the swirl flow, formed along the inner wall of the combustor. The authors utilized this combustor as a flame holder, to burn a high velocity jet flowing axially in the central part, and named this combustor a cyclone-jet combustor. In general, it is difficult for the low NO_x combustion to occur in spray combustion. In the present study, experiments on the spray combustion by the cyclone-jet combustor were carried out, and comparing the co-axial fuel spray and fuel gas jet flames. Kerosene and propane were used for fuel. With the air flow rate changed, the effect of the premixing on the NO_x formation was examined. It was shown that the increase of the air flow rate reduces the NO_x emission, and the shape of the spray flames is almost the same as the gas flames. The results suggest that the premixing after the process of the injection of fuel becomes very effective for NO_x reduction in spray combustion.