Investigation on Removal of NO_x and SO₂ From Flue Gas by Combined Ozone With Absorption and By-Product Treatment

The combination of ozone with washing tower and an absorption products recovery system was utilized for removal of NO_x and SO₂ from flue gas. In our previous studies, more than 90% NO can be oxidized by ozone. In this study, three kinds of absorbents, Na₂SO₃, CaSO₃ and Ca(OH)₂, were evaluated for simultaneous absorption of NO₂ and SO₂ in the wet scrubbing. It was found that NO₂ absorption efficiency was increasing with S(IV). Effect of different concentration of CaSO₃ on NO₂ absorption was investigated. Results show that nearly 70% NO₂ can be absorbed in calcium sulfite slurry. Furthermore, NO₂ absorption efficiency is increasing to 85% in the sulfite with assistant of MnSO₄. In the meantime, the absorption efficiency of SO₂ is always nearly 100%. A new system is built for recycling NO₂ absorption products and purifying the waste water, which has the advantages of low investment and operating cost.