Engineering practice and economic analysis of ozone oxidation wet denitrification technology

SO₂ and NO emitted from coal-fired power plants have caused serious air pollution in China. In this study, a test system for NO oxidation using O₃ is established. The basic characteristics of NO oxidation and products forms are studied. A separate test system for the combined removal of SO₂ and NO_x is also established, and the absorption characteristics of NO_x are studied. The characteristics of NO oxidation and NO_x absorption were verified in a 35 t·h^-1 industrial boiler wet combined desulfurization and denitrification project. The operating economy of ozone oxidation wet denitrification technology is analyzed. The results show that O₃ has a high rate and strong selectivity for NO oxidation. When O₃ is insufficient, the primary oxidation product is NO₂. When O₃ is present in excess, NO₂ continues to get oxidized to N₂O₅ or NO₃. The removal efficiency of NO₂ in alkaline absorption system is low (only about 15%). NO_x removal efficiency can be improved by oxidizing NO_x to N₂O₅ or NO₃ by increasing ozone ratio. When the molar ratio of O₃/NO is 1.77, the NO_x removal efficiency reaches 90.3%, while the operating cost of removing NO_x per kilogram is 6.06 USD (NO₂).