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Simultaneous Removal of SO₂ and NO Using H₂O₂/Urea Activated by Vacuum Ultraviolet Light in a Pilot-Scale Spraying Tower

Xie, Wenxia, Xu, Chengwei, Zhang, Jun, Liu, Yangxian, Xi, Jianfei, Lv, Jianhong, Gu, Zhongzhu
Energy & fuels 2019 v.33 no.2 pp. 1325-1333
flue gas, fuels, hydrogen peroxide, hydroxyl radicals, ion exchange chromatography, irradiation, liquids, nitrates, nitric oxide, photochemistry, spraying, sulfates, sulfur dioxide, ultraviolet radiation, urea
A study on simultaneous removal of SO₂ and NO from flue gas using H₂O₂/urea activated by vacuum ultraviolet (VUV) light was carried out in a pilot-scale photochemical spraying tower. The effects of different operational variables on simultaneous removal efficiencies of SO₂ and NO were investigated. The gaseous and liquid removal products were detected by the flue gas analyzer and ion chromatography (IC), respectively. The removal pathways of SO₂ and NO were analyzed. The application prospect of this new method was also preliminarily discussed. Results show that under most of the process conditions tested, SO₂ can attain complete removal. Removal efficiency of NO is enhanced under increasing the VUV irradiation intensity and H₂O₂ concentration, but it is inhibited by an increase of the flue gas flow and NO concentration. The urea concentration and liquid–gas ratio have a dual influence on NO removal, and its removal efficiency increases first and then decreases. SO₂ concentration has little impact on NO removal. IC results show that SO₄²– and NO₃– are the main removal products in solution. •OH derived from VUV activation of H₂O₂ plays the crucial role in NO removal.