Abstract: The invention relates to an improvement in atomizing methods and apparatus useful for combusting liquid fuel, such oil. The atomizing methods and apparatus consistently produce liquid fuel streams having vary narrow spray angles. The liquid fuel streams having very narrow spray angles can be produced even when a low liquid fuel flow rate is employed and even when a liquid fuel stream is atomized outside a liquid fuel passageway. The production of the constant narrow spray angle liquid fuel stream allows the atomizing apparatus to operate for a long period without causing fouling problems even if they are sufficiently recessed from internal openings of refractory ports defined in the furnace wall.

Abstract: A combustion method is provided for carrying out combustion with reduced generation of nitrogen oxides. The combustion method involves partially combusting a fluid fuel stream with a low velocity oxidant and thereafter mixing and combusting the resulting product with a secondary oxidant stream diluted with ambient gas. The velocity of the secondary oxidant stream is either increased to reduce the nitrogen oxides emission level or adjusted to provide the desired secondary oxidant/low velocity oxidant ratio which is useful for further decreasing the formation of nitrogen oxides. Normally, increasing the ratio and/or velocity further decreases the nitrogen oxides emission level. When liquid fuel is employed, it is atomized with atomizing fluid in such a manner to produce a liquid fuel stream having a very narrow spray angle. The production of such a stream allows the burner to be operated without water cooling.