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 is selected from the group consisting of atomized hydrocarbon liquid and pulverulent hydrocarbon solids, 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 as a stream containing at least 35 vol.% O 2 into said fuel by injecting it directly into said fuel in said primary combustion zone as said fuel emerges from said burner, so that the oxygen combusts with said fuel in said fuel-rich zone, wherein said oxygen is fed into said fuel 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, characterised in that, said oxygen is injected directly into said fuel through a lance having a closed end and having at least two nozzles provided along the perimeter of the lance near the closed end of the lance, each of which forms an angle of 30 to 90 degrees with respect to the reverse of the direction of flow of oxygen into the lance. 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 is selected from the group consisting of atomized hydrocarbon liquid and pulverulent hydrocarbon solids, 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 as a stream containing at least 35 vol.% O 2 into said fuel by injecting it directly into said fuel in said primary combustion zone as said fuel emerges from said burner, so that the oxygen combusts with said fuel in said fuel-rich zone, wherein said oxygen is fed into said fuel 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, characterised in that, said oxygen is injected directly into said fuel through a lance having a closed end and having at least two nozzles provided along the perimeter of the lance near the closed end of the lance, each of which forms an angle of 30 to 90 degrees with respect to the reverse of the direction of flow of oxygen into the lance.