Effective Removal of Nitrogen Oxides from Smokestack Emissions at Coke Plant

Abstract

The formation of nitrogen oxides (NO_x) in the smokestack gases of coke plants is investigated; oxides of thermal, fuel, and prompt types are present. Thermal nitrogen oxides are studied on the assumption that nitric oxide predominates. Proportions of different types of nitrogen oxides for use in calculating the total emissions are recommended. Profound removal of nitrogen oxides from the flue gases is proposed, on the basis of selective noncatalytic and catalytic reduction of nitrogen oxides by ammonia. Calculations show that, in noncatalytic reduction, it is expedient to introduce ammonia in the descending regeneration line for furnaces of PK type at a distance of 73 cm from the top of the regenerator, within the 900°C temperature band. Complete consumption of the ammonia surge in a second stage of selective catalytic reduction is recommended. The modules with applied catalyst should be placed in the coke battery flue. Calculations indicate that this method ensures 95% removal of nitrogen oxides, with complete elimination of ammonia from the emissions.