Low nox emission diffusion flame combustor for gas turbines

A diffusion flame combustor for gas turbines comprising a fuel injector unit (4) mounted at one end of a flame tube (6) delimits a combustion chamber (6a) and has its other end connected to a duct (11) that conveys the combustion gases to the turbine. The flame tube is coaxially mounted inside a tubular container (2) that communicates with the discharge casing (5) of an air compressor and, together with the tube, defines a space (30) for the combustion air. The injector unit (4) comprises an injector head (9) facing into the combustion chamber (6a) and provided with at least one fuel gas injection nozzle (29), which comprises an air-gas premixing duct (28) into which the fuel gas is introduced, the duct having an inlet section that communicates with the air space (30) and being provided with a radial-fin air swirler (31) arranged upstream of the point at which the fuel gas enters said premixing duct (28). The partial premixing of the combustion gas with the combustion air assists in reducing the NOx emissions and the production of unburnt materials.