PROCESS FOR CONTROLLING NITROGEN OXIDES IN EXHAUST GASES AND APPARATUS THEREFOR

摘要

+ In a process and an apparatus for controlling oxides of nitrogen in exhaust gases from combustion equipment by decomposing the oxides, in the presence of oxygen, with ammonia blown into t? equipment and associated ducting at temperatures within the range from 700.degree. to 1300.degree.C, a catalyst assembly is arranged, with the catalytic surfaces of the component units substantially in parallel to the direction of exhaust gas flow, in a region where the temperature of the gas after the decomposing treatment is between 300.degree. and 500.degree.C, and the gas after the decomposing treatment is caused to pass through the catalyst assembly to decompose residual nitrogen oxides and ammonia in the gas to innocuous substances. An additional supply of ammonia, in an amount from 0.5 to 1.5 times equivalent (in molar ratio) to the amount of nitrogen oxides in moles in the gas is introduced into the space immediately upstream of the catalyst assembly, thereby to accelerate the decomposition of the oxides in the gas to make it harmless.