Using Chlorine Dioxide to Remove NOx in Low-Temperature Flue Gas

Wet scrubbing is an economical and effective denitration method in low-temperature flue gas. ClO2 is a highly efficient oxidant and is economical. Using ClO2 to remove NO can be expected to become a more ideal method. A detailed study of using ClO2 to remove nitrogen oxides (NOx) in low-temperature flue gas is performed, and meaningful results have been obtained. With the increase of the molar ratio of ClO2:NO, from 0.5 to 1.0, the oxidation efficiency of NO increases linearly, from 55% to 90%. With the increase of moisture concentration, from 0.5% to 9%, the NO oxidation efficiency increases slowly, from 75% to 90%. With the increase of flue gas temperature, NO oxidation efficiency and the denitration efficiency decrease slowly. The presence of SO2 improves the denitration efficiency, from 75% to 80% with 20 ppm SO2. The acidic absorbent is beneficial to denitration, but will also aggravate the escape of HCl, similar to 20 ppm. NOx is converted into nitrate in the sorbent when the supply of ClO2 is sufficient, otherwise nitrite will be produced. The NOx in the outlet gas is almost NO2. Through experimental research, a new idea for denitration by ClO2 is proposed, using acid sorbent to oxidize NO and alkali sorbent to absorb NO2. This study is of great help to the subsequent engineering application.