Patent ID: 8113822
Filing Date: 2012-02-14
Classification: F23J,F23N

Abstract:
1. A combustion method for allowing gas generated on combustion of fuel in a burner to be in contact with an oxidation catalyst, thereby decreasing nitrogen oxides contained in the gas, comprising: a combustion step in which hydrocarbon-containing fuel is burned in a burner, thereby generating gas free of hydrocarbons but containing oxygen, nitrogen oxides and carbon monoxide; an endothermic step of absorbing heat from gas generated in the combustion step by endothermic device; a hazardous-substance decreasing step in which the gas is brought into contact with an oxidation catalyst after the endothermic step, thereby oxidizing carbon monoxide contained in the gas by oxygen and reducing nitrogen oxides by carbon monoxide; and a concentration ratio adjusting step in which a concentration ratio of oxygen, nitrogen oxides and carbon monoxide on the primary side of the oxidation catalyst is adjusted based on concentration ratio characteristics of the burner and the endothermic device by using air-ratio adjusting device of the burner to a predetermined concentration ratio at which the concentration of nitrogen oxides on the secondary side of the oxidation catalyst is decreased to substantially zero or a value lower than a predetermined value and the concentration of carbon monoxide is also decreased to substantially zero or a value lower than a predetermined value, wherein the concentration ratio adjusting step includes a concentration ratio adjusting step in which a concentration ratio K of oxygen, nitrogen oxides and carbon monoxide contained in gas on the primary side of the oxidation catalyst is adjusted based on the concentration ratio characteristics of the burner and the endothermic device by using the air-ratio adjusting device of the burner to any one of the following Adjustment 0, Adjustment 1 and Adjustment 2, where in Adjustment 0, the concentration ratio K is adjusted to a predetermined reference concentration ratio K in Adjustment 1, the concentration ratio K is adjusted to a first predetermined concentration ratio K in Adjustment 2, the concentration ratio K is adjusted to a second predetermined concentration ratio K a formula for determining the concentration ratio K is given as the following formula (1), the concentration ratio K and the predetermined reference concentration ratio KO satisfy the following formula (2), the first predetermined concentration ratio K (in formula (1), [CO], [NOx] and [O 2 ] denote the respective concentrations of carbon monoxide, nitrogen oxides and oxygen. satisfying the condition of [O 2 ]>0).