Method and arrangement for injecting an emulsion into a flame

The invention relates to an arrangement for injection of an emulsion of a first fluid and a second fluid into a flame of a burner (1), wherein the arrangement comprises: - a central gas duct (6) extending along a longitudinal central axis from an upstream end to a downstream end, - an outer gas channel (57) disposed coaxially with said gas duct (6), - a fluid channel (54) disposed coaxially between said gas duct (6) and said outer gas channel (57), forming a downstream contracting annular fluid channel, - said central gas duct (6) and said fluid channel (54) separated by a first frustoconical wall (60) at its downstream end terminating in an annular inner lip (50), - said fluid channel (54) and said outer gas channel (57) separated by a second frustoconical wall (61) at its downstream end terminating in an annular outer lip (53), -said arrangement mounted concentrically surrounding a heat source (5) providing through said gas duct (6) hot gases (32) being directed into the flame (7) of the burner (1), - a mixing device (47) for forming said emulsion of the first fluid and the second fluid and for letting said emulsion out into said contracting annular fluid channel (54) and for injecting said emulsion from said annular fluid channel (54) into said flame (7). According to the invention NOx emissions from the combustion of the main flame are reduced.