Simultaneous Removal of SO₂ and NO from Flue Gas Using Multicomposite Active Absorbent

Abstract

A multicomposite active absorbent was prepared using the liquid-phase complex of NaClO2 and NaClO as well as solid-phase slake lime to simultaneous desulfurization and denitrification at a flue gas circulating fluidized bed (CFB). The effects of influencing factors on the removal efficiencies of SO2 and NO were investigated. Removal efficiencies of 96.5% for SO2 and 73.5% for NO were obtained, respectively, under the optimal experimental conditions. The characterization of the spent absorbent was carried out by using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and chemical analysis methods, from which the simultaneous removal mechanism of SO2 and NO based on this absorbent was proposed.

Integrative process of preoxidation and absorption for simultaneous removal of SO2, NO and Hg0

“…(12)) was also contributed to the oxidation reactions [15,23,26,28,35,44]. Moreover, ClO 2 could generate Cl Á and Cl 2 via the reactions of 15 to 17, which had been demonstrated previously [15,28,44].…”

“…For a coal-fired power plant, the actual flue gas consists chiefly of N 2 , CO 2 , O 2 , SO 2 , NO x etc., in which the concentrations of CO 2 and O 2 are generally 10-15% and 5-6%, respectively, and those of SO 2 and NO x will change with coal species and combustion conditions of the boiler [35]. In order to investigate the interactions of the coexistence gases in coal-fired flue gas with SO 2 , NO and Hg 0 , the simultaneous removal experiments with various concentrations of O 2 , CO 2 , NO and SO 2 were carried out.…”

“…Based on the related literature references [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]44], we inferred that the main functional oxidants in the reaction system were ClO 2 À , ClO 2 , Cl 2 , ClÁ and Br 2 . From the electrochemistry, the standard electrode potentials of ClO 2 À /Cl À (1.599 V), ClO 2 /Cl À (1.511 V), Cl 2 /Cl À (1.396 V) and Br 2 /Br À (1.09 V) are higher than those of Hg 2+ /Hg 0 (0.796V), SO 4 2À /H 2 SO 3 (0.172 V), SO 4 2À /SO 2 (0.158V), NO 2 /NO (1.049 V), NO 3 À /NO (0.957 V), NO 2 À /NO (-0.460V) and NO 3 À /NO 2 À (0.835 V), indicating that the oxidation of SO 2 , NO and Hg 0 by vaporized ACO can occur.…”

Simultaneous removal of SO 2 , NO and Hg 0 through an integrative process utilizing a cost-effective complex oxidant

“…The experimental results revealed that the elevated pH ranging from 4.5 to 7.0 was unfavorable for the removal of NO and Hg 0 , which might be a consequence of the followed reasons. On the one hand, it had been known that the acidic environment was preferable for the H 2 O 2 -induced oxidation reaction [18], whereas the increasing pH in the range of 4.5-7.0 would accelerate the decomposition of H 2 O 2 due to the excessive HO 2 − generations (Eq.…”

“…The SO 2 and NO concentrations in actual flue gas always change with various operation conditions [18]. Importantly, they have great influences on the Hg 0 removal [19][20][21][22][23][24], so a series of experiments with different concentrations of NO and SO 2 were carried out.…”