Abstract: A gas turbine combustor comprises a combustion chamber, a premixing chamber in which hydrocarbon fuel and air are premixed, a nozzle with swirler for swirling and injecting the premixed fuel and air into the combustion chamber, to effect premixed combustion, and a fuel nozzle projecting into the combustion chamber and adapted to inject fuel at region wherein the premixed combustion is completed, so as to effect low air-ratio diffusion combustion thereby to produce reducing substance. NOx produced by the premixed combustion is reduced by reducing reaction with the reducing substances, so that the NOx concentration in the combustion gas is reduced. The combustor further includes an after-air ports on a peripheral wall defining the combustion chamber to effect combustion of unburnt substances.

Abstract: A low NOx burning method and apparatus wherein a low air ratio flame burned with an amount of air less than an amount of air in a theoretical air ratio required for burning fuel perfectly is formed, and combustibles discharged from the low air ratio flame are burned at a trailing stream of the low air ratio flame while supplying air. The low air ratio flame is a premixing flame burned by premixing the fuel and air, and combustion of the premixing flames is maintained in the vicinity of the premixing flame. In this way, the generation of the NOx during the burning can be greatly decreased, and the required apparatus can be small-sized.