Low NOx emission diffusion flame combustor for gas turbines

x A diffusion flame combustor for a gas turbine comprising a flame tube that delimits a combustion chamber, the flame tube having a fuel injector unit mounted at one end, the other end of the tube being connected to a duct that conveys combustion gases to the turbine. The flame tube is mounted coaxially inside a generally tubular container that communicates with the discharge casing of an air compressor and, together with the tube, defines a space for combustion air. The injector unit comprises an injector head facing generally into the combustion chamber and provided with at least one fuel gas injection nozzle. The nozzle includes an air-gas premixing duct into which fuel gas is introduced. The premixing duct has an inlet section that communicates with the air space and is provided with a radial-fin air swirler generally upstream of a point at which the fuel gas enters the premixing duct. This partial premixing of combustion gas with combustion air reduces NOemissions and production of un-combusted material.