Simultaneous desulfurization and denitrification with hypochlorite oxidant

doi:10.16085/j.issn.1000-6613.2023-1447

Abstract

Abstract:

Comparative experiments on the simultaneous removal of NO and SO₂ from simulated smelting flue gas were carried out using two hypochlorite salts of NaClO and Ca(ClO)₂, respectively, in a tandem bubbling reactor. The effects of operation parameters such as the oxidizing agent concentration, the number of reactors, the reaction temperature, and the pH of the solution on the removal efficiency were investigated. The results showed that, when the hypochlorite oxidant was used, the removal of SO₂ was always good and the removal efficiency of NO increased with the increase of the oxidant concentration and reactor number. With the increase of reaction temperature and solution pH, the removal of NO by hypochlorite oxidant gradually weakened. Comparison results showed that Ca(ClO)₂ has better desulfurization and denitrification efficiency than NaClO. Under the optimal reaction conditions, the best simultaneous desulfurization and denitrification efficiencies of 95.4% and 88%, respectively, were obtained with a Ca(ClO)₂ concentration of 25mmol/L, three reactors in series, reaction temperature of 25℃, and pH=6. In addition, the reaction mechanism of simultaneous desulfurization and denitrification by hypochlorite absorber was also proposed, in which NO was converted into NO₂^- and NO₃^- by contact reaction with hypochlorite oxidizer, and SO₂ was oxidized into SO₄^2-, and CaSO₄ precipitation would be generated in the case of Ca(ClO)₂, so that NO and SO₂ could be removed in the process.

Key words: sodium hypochlorite, calcium hypochlorite, desulfurization and denitrification, smelting flue gas, bubble column reactor

摘要：

为了实现冶炼烟气的有效脱硫脱硝，采用两种次氯酸盐——NaClO和Ca(ClO)₂在串联式鼓泡反应器中对模拟冶炼烟气进行了同时去除NO和SO₂的对比性实验。考察了两种氧化剂的浓度、反应器个数、反应温度以及溶液的pH等参数对同时去除NO和SO₂效率的影响。结果表明，当使用次氯酸盐氧化剂时，SO₂均稳定在较好的去除范围内，NO的去除效率随着氧化剂浓度的升高和反应器个数的增加而提高，随着反应温度的升高和溶液pH的增大而减小。两种氧化剂的对比实验表明，相较于NaClO来说，Ca(ClO)₂具有更好的脱硫脱硝效率。在最佳反应条件下，即Ca(ClO)₂浓度为25mmol/L、反应器个数为3、反应温度为25℃、溶液pH为6时，有最佳的同时脱硫脱硝效率，分别为95.4%和88%。此外，还提出了次氯酸盐吸收剂同时脱硫脱硝的反应机理，NO与次氯酸盐氧化剂进行接触反应生成NO₂^-和NO₃^-，SO₂则与之反应生成SO₄^2-，在与Ca(ClO)₂反应时会生成部分CaSO₄沉淀，NO和SO₂在此过程中得以去除。

关键词: 次氯酸钠, 次氯酸钙, 脱硫脱硝, 冶炼烟气, 鼓泡反应器

CLC Number:

LI Yi, LIANG Lisi, ZHANG Lixing, QIAO Jiangyu, CUI Zhongyi, CHEN Jin, XU Qiang, ZHAO Chen. Simultaneous desulfurization and denitrification with hypochlorite oxidant[J]. Chemical Industry and Engineering Progress, 2024, 43(9): 5282-5289.

李一, 梁李斯, 张立兴, 乔江鱼, 崔忠宜, 陈进, 徐强, 赵晨. 次氯酸盐氧化剂同时脱硫脱硝一体化[J]. 化工进展, 2024, 43(9): 5282-5289.

Figures/Tables 6

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