Combustion apparatus and wind box

A combustion apparatus comprising:

• a burner burning a fuel within a furnace in a theoretical air ratio or less;
• a plurality of air ports arranged downstream of the burner and placed along a width direction of the furnace, each of said plurality of air ports being separated into an air injection port injecting additional combustion air into the furnace and an inhibiting gas injection port injecting a nitrogen oxide generation inhibiting gas constituted by at least one gas selected from the group consisting of combustion exhaust gas and a mixed gas of the combustion exhaust gas and air inhibiting a nitrogen oxide from being generated in a mixing region formed by both of a combustion gas generated by burning the fuel by means of said burner and the additional combustion air injected from said air port or near the mixing region, and including a flow rate regulator, wherein said inhibiting gas injection port is provided on an outer peripheral portion of said air injection port, at least a part of said outer peripheral portion being on a burner side of said air injection port, and wherein the flow rate regulators of the plurality of air ports are configured to provide more flow of the nitrogen oxide generation inhibiting gas to an air port close to the furnace center portion than to the air port close to the furnace side wall of the plurality of air ports;
• and
• at least one blower for circulating combustion exhaust gas from an outlet of the furnace to an inlet of the flow path injecting a nitrogen oxide generation inhibiting gas, and for supplying the additional combustion air to the flow path injecting additional combustion air into the furnace.