Simultaneous Absorption of NOx and SO_2 in Oxidant-Enhanced Limestone Slurry

摘要

In this article, a study of simultaneous absorption kinetics of NOx and SO_2 in oxidant-enhanced limestone slurry using sodium chlorite as additives is presented. The laboratory-scale experiments were performed in a double-stirred tank reactor, and the effect of inorganic ions and operating parameters on absorption rates was investigated. The results indicate that NOx absorption rate shows a positive order with respect to NO (0.573), SO_2 (0.278), and NaClO_2 (0.194), whereas SO_2 absorption rate shows a first order with respect to SO_2 and zero order for both NO and NaClO_2 under a typical limestone wet flue gas desulfurization operating condition. Higher pH leads to a decrease of NOx absorption rate but has no significant influence on SO_2 absorption. The SO_2 absorption rate decreases with the increase of temperature, whereas the NOx absorption rate remains nearly constant. S(Ⅳ) in the slurry reduces the NOx absorption rate dramatically and suppresses the SO_2 absorption, whereas the presence of nitrate ions can increase the absorption rate of both SO_2 and NOx. High concentration of Cl~- has a positive effect on the SO_2 absorption, whereas it has a negative effect on NOx absorption rate. Additionally, Mg~(2+) and F~- have no impact on SO_2 and NOx absorption rates.