THICK AND THIN COMBUSTION BURNER

PROBLEM TO BE SOLVED: To improve the combustion performance of a thick and thin combustion burner even when the combustion amount of the burner is near its lower limit by expanding TDR by changing the ratio of the amount of a thin mixed gas to that of a thick mixed gas in accordance with the change of the combustion amount. SOLUTION: The thick mixed gas in a discharging section 16 is blown out to a gas passage 36 from a plurality of gas blowing-out holes 21-25 and diluted into the thin mixed gas by the air in the passage 36 and the thin mixed gas is supplied to thin burner ports and forms thin flames. The gas blowing-out holes 25, 22 and 24 are respectively faced to the gas blowing holes and 23 and 25 and, when the combustion amount is large, the ratio of the amount of the thin mixed gas to that of the thick mixed gas is decreased by increasing blowout resistances by bringing the blown-out gases into collision with each other and, when the combustion amount is small, the ratio is increased by decreasing the blowout resistances.