COMBUSTION DEVICE

PURPOSE:To provide a combustion device, restraining the generation of thermal NOx and prompt NOx, compact and capable of reducing fun then the generating amount of NOx. CONSTITUTION:This device is constituted of a fan 4, a burner case 5, into which combustion air is sent from the fan 4, burners 6, 6, ..., equipped with a flame port unit 14 ejecting mixture gas produced by premixing gas fuel and combustion air and provided in the burner case 5 in parallel to each other, ventilating passages 7, 7, ..., formed so as to be neighbored to the burners 6, 6, ... respectively, and a fuel supplying device 8, supplying gas fuel to the ventilating passages 7, 7, ... and the burners 6, 6, ... Primary mixture gas, having the air ratio of 1-1.3, is ejected from the flame port unit 14 of the burners 6 while secondary mixture gas, having the air ration of 1.5 or more, is conducted though the ventilating passages 7 so sa to flow out therethrough.