PURPOSE: To realize a great deal of reduction of NOx formation by forming a pair of cooling fins in a bag shape having an opening as secondary air introduction port, providing a secondary air hole on a vertical surface of the cooling fin, and arranging the cooling fin above a secondary air passage between combusiton tubes.
CONSTITUTION: A cooling fin 5 is formed in a bag shape which is opened at the lower end as secondary air introduction port 6, and a secondary air hole 8 is provided on the vertical surface on the both sides. The cooling fin 5 is arranged above a secondary air passage 3 between combustion tubes 1. The secondary air holes 8 of the adjacent cooling fins 5 oppose to the surface of a flame hole 2, whereby scondary air jetted from the secondary air holes 8 collides with combusiton gas dispersedly and burns. Thus, by the lowering of temperature of the flame and the dispersed collision and buring of air and gas by means of the cooling fin 5, generation of NOx can be decreased by a great deal.
SHIMAZU MASAHIKO
OKADA HIDEYUKI
UEDA HIDEO
