Patent ID: 7959892

Claim:
A method for treating a regenerator flue gas stream comprising (A) providing from a catalyst regenerator a regenerator flue gas stream that contains carbon monoxide in a concentration less than 10,000 ppm and contains NOx in an amount up to 1,000 ppm; (B) feeding fuel comprising natural gas at a rate of 2 to 14 scfh into a chamber through a first orifice whose diameter is 0.3 to 1.0 mm, feeding oxygen at a rate of 16 to 72 scfh into said chamber, mixing said fuel and said oxygen in said chamber and combusting a portion of the oxygen in the mixture with said fuel in said chamber to form a hot oxidant stream that contains oxygen emerging from said chamber through a second orifice whose diameter is 1.5 to 2.65 mm and whose distance from said first orifice is 1.0 to 3.5 in, wherein the rate at which said fuel is fed into said chamber, the rate at which said oxygen is fed into said chamber, the diameters of said first and second orifices, and the distance between said first and second orifices, provide that the residence time of said combustion in said chamber is long enough that said hot oxidant stream has a temperature higher than the temperature of said regenerator flue gas and provide that said residence time is short enough that said hot oxidant stream contains products of said combustion including radicals selected from the group consisting of radicals corresponding to the formulas O, H, OH, C 2 H, CH 2 , C j H 2j+1 or C j H 2j−1 wherein j is 1-4, and mixtures of two or more of such radicals; (C) feeding the hot oxidant stream into the regenerator flue gas stream to raise the temperature of the regenerator flue gas to a temperature higher than 1100 F that is higher than the temperature of the flue gas stream to which the hot oxidant stream is added, wherein the hot oxidant stream is added at a rate sufficient to convert carbon monoxide in the regenerator flue gas to carbon dioxide.