Simultaneous removal of NOxand SO2using two-stage O3oxidation combined with Ca(OH)2absorption

This paper proposes two-stage O(3)oxidation combined with Ca(OH)(2)for simultaneous removal of NO(x)and SO2(NOx: Nitrogen oxides including NO, NO(2)and N2O5). In two-stage oxidation, NO was first oxidized to NO(2)in an oxidation tube, and NO(2)was further oxidized into N(2)O(5)in the spray tower. NO(x)and SO(2)were simultaneously removed in the spray tower. This method can effectively reduce the extra waste of O(3)caused by the decomposition of N2O5, especially at high temperature. Effects of various factors on denitrification efficiency were investigated. The results showed that the NO(x)removal efficiency decreased and O(3)extra consumption ratio increased with the increase of oxidation temperature or oxidation reaction time. When the O-3/NO molar ratio was 1.8, one-stage O(3)oxidation at 150(o)C extra wasted 33.3% of O-3. With the increase of O(3)concentration at site 2, the NO(x)removal efficiency first increased and then stabilized. Compared with the one-stage O(3)oxidation-absorption, the two-stage oxidation-absorption improved NO(x)removal efficiency from 62.5% to 89%. In addition, the increase of CaSO(3)slurry concentration had little effect on the denitrification efficiency.