Provided is a combustor that is made compact and achieves NOx reduction. In the combustor (1) including a pilot nozzle (21) disposed along the central axis of the combustor (1) and performing diffusion combustion, a plurality of main nozzles (22) disposed on the outer peripheral side of the pilot nozzle (21) at intervals in the circumferential direction and performing premixing combustion, a single inner cylinder (2a) surrounding the pilot nozzle (21) and the main nozzles (22), and an outer cylinder approximately coaxially surrounding the outer side of the inner cylinder (2a) to form a compressed air passage (6) between the inner peripheral surface thereof and the outer peripheral surface of the inner cylinder and turning the flow direction of compressed air flowing in the compressed air passage (6) in approximately the opposite direction at the end of the inner cylinder (2a) to introduce the compressed air into the pilot nozzle (21), the compressed air passage (6) is provided with a flow rate controller that makes the flow rate on the combustor (1) inner peripheral side of the passage larger than that on the outer peripheral side. An example as the flow rate controller is a baffle plate 51 provided with holes 55, 56.

A startup burner assembly for a recovery boiler, the startup burner assembly includes a housing having a burner end and a second end distal to the burner end; a main fuel conduit disposed within the housing; and at least one high-pressure air conduit disposed within the burner end of the housing. The high-pressure air conduit includes at least one angled air injection nozzle configured to direct high-pressure air exiting the burner end of the startup burner assembly in a rotational direction.

A furnace-heating combustion apparatus that allows adjustment of a ratio between the amount of primary air and the amount of secondary air. A double-tube elongate burner extends through a rear wall portion of an air box disposed away from a furnace wall. The leading end portion of the burner is disposed inside a tube section such that a secondary air conduit is formed between an outer circumferential face of the leading end portion and an inner circumferential face of the tube section. A primary air conduit is provided at the leading end portion of the burner to introduce the air inside the air box from the rear end portion and cause it to flow toward the leading end portion. A burner supporting means is provided for to allow adjustment of the position of the burner in the longitudinal direction relative to the rear wall of the air box.

A startup burner assembly for a recovery boiler, the startup burner assembly includes a housing having a burner end and a second end distal to the burner end; a main fuel conduit disposed within the housing; and at least one high-pressure air conduit disposed within the burner end of the housing. The high-pressure air conduit includes at least one angled air injection nozzle configured to direct high-pressure air exiting the burner end of the startup burner assembly in a rotational direction.