Patent ID: 7438005

Claim:
A combustion method that reduces the amount of NOx emitted comprising: providing a combustion device that has a primary combustion zone and a burn out zone; feeding air, and nonaqueous fuel that contains bound nitrogen and comprises pulverized coal, through a burner into said primary combustion zone; and combusting the fuel in a flame in the primary combustion zone that has a fuel-rich zone, while feeding oxygen into said fuel by injecting it directly into said fuel in said primary combustion zone as said fuel emerges from said burner or by adding it to the air that is fed through said burner, so that the oxygen combusts with said fuel in said fuel-rich zone, in an amount of said oxygen which is less than 20% of the stoichiometric amount required for complete combustion of said fuel, and adjusting the amount of air fed through said burner so that the stoichiometric ratio in said primary combustion zone is between 0.6 and 0.99, and adding air into said burn out zone from a source other than said burner in an amount containing sufficient oxygen that the total amount of oxygen fed into said device is at least the stoichiometric amount needed for complete combustion of said fuel, and combusting residual combustibles from said primary combustion zone in said burn out zone.