To provide a gas injection port of a simple structure capable of stabilizing the mixing of unburned gas near a furnace wall, achieving an independent furnace central portion carry-over function, oxidatively decomposing a lean unburned gas by stabilizing ignition near an air port nozzle and the like, and performing low NOx combustion.
This gas injection port is provided with a secondary air flow channel 23 for producing contracted flow, obliquely formed toward a center shaft from an upstream side of the air flow to provide the flow of secondary air 3 with a velocity component from an outer peripheral side of AAP 17 toward the center shaft, a guide plate 10 disposed at an outlet portion of the secondary air flow channel 23 to guide the gas flow along a throat portion 1a of a furnace 1, and a swirling unit 8 disposed at the upstream side of the secondary air flow channel 23. As the turbulence around jet is generated in the furnace 1 near the outlet portion of the secondary air flow channel 23, the surrounding combustion gas is easily accompanied therewith, and the swirl jet of the gas formed by the swirling unit 8 has the expansion of jet wider than the contracted flow, the blowing-through of the rising unburned gas can be prevented, and further the guide plate 10 prevents the attachment of ash onto a furnace wall.
KURAMASU KIMIHARU
TANIGUCHI MASAYUKI
Iizuka Muko