PURPOSE: To minimize a generation of NOx in combustion gas, by employing a burner capable of conducting a high temperature reducing combustion with lower content of NOx emission and inhibited generation of thermal NOx, and to obtain a stable burner flame even though the highly-concentrated combustion gas is recirculated into the combustion zone.
CONSTITUTION: Flame protecting gas burner nozzle 1 is located in a path of primary air 10. Flame protecting jet 13 is expelled radially outwardly of the nozzle 1 and is directed towards an annular flame protecting ring 3. A main gas burner nozzle 8 is located in a path of secondary air 11. A fresh air should be employed for both primary and secondary air. Such a construction ensures improved flame-protectability of the primary combustion zone. A main gas burner jet 14, which is emitted from the nozzle 8 towards a front side of flame generated from the nozzle 1, has a radial and spiral flow direction aligned with the rotational direction of a tertiary air 12, enabling a high temperature reducing combustion with lower NOx emission in the primary combustion zone. The tertiary air 12 is compulsively circulated in the form of gas mixture with combustion gas. The respective air flow rates are so adjusted as to increase in the order of primary air, secondary air and tertiary air so that a circulation zone of combustion gas mixed with the tertiary air 12 can be expanded in the vicinity of burner throat 6.
JINBO TADASHI
ORIMOTO MANABU
MASAI TADAHISA
