LOW NOx COMBUSTION APPARATUS

A low NOx combustion apparatus, comprising:

• a burner for burning a fuel by combustible air to generate a gas containing nitrogen oxides by combustion;
• an endothermic device for absorbing heat from the gas;
• a catalyst device having a catalyst component for decreasing nitrogen oxides contained in the gas after passing through the endothermic device;
• a first poisoning substance removing device for removing a poisoning substance containing at least sulfur, which is contained in the fuel and adsorbs to the catalyst component or reacts with the catalyst component to form a compound;
• and
• a second poisoning substance removing device provided on a primary side of the catalyst device for removing a poisoning substance containing at least sulfur, which is contained in the gas and adsorbs to the catalyst component or reacts with the catalyst component to form a compound.

A low NOx combustion apparatus, comprising:

• a burner for burning a fuel by combustible air to generate a gas containing oxygen, nitrogen oxides, and carbon monoxide by combustion;
• an endothermic device for absorbing heat from the gas;
• a catalyst device having a catalyst component for oxidizing carbon monoxide contained in the gas after passing through the endothermic device and reducing nitrogen oxides contained in the gas by carbon monoxide;
• a first poisoning substance removing device for removing a poisoning substance containing at least sulfur, which is contained in the fuel and adsorbs to the catalyst component or reacts with the catalyst component to form a compound;
• a second poisoning substance removing device provided on a primary side of the catalyst device for removing a poisoning substance containing at least sulfur, which is contained in the gas and adsorbs to the catalyst component or reacts with the catalyst component to form a compound;
• a sensor for detecting an air ratio of the burner;
• and
• an air-ratio adjusting device for controlling an air ratio of the burner to a set air ratio based on a detected signal of the sensor,
• wherein the burner and the endothermic device are configured so as to adjust a concentration ratio of oxygen, nitrogen oxides, and carbon monoxide in a gas on a primary side of the catalyst device to a predetermined concentration ratio at which a concentration of nitrogen oxides on a secondary side of the catalyst device is decreased to substantially zero or a predetermined value of less, and a concentration of carbon monoxide on the secondary side of the catalyst device is decreased to substantially zero or a predetermined value or less, when the air ratio is adjusted to the set air ratio by the air-ratio adjusting device.