Simultaneous Desulfurization and Denitrification of Flue Gas by •OH Radicals Produced from O2+ and Water Vapor in a Duct

In the present study, simultaneous flue gas desulfurization and denitrification are achieved with center dot OH radicals generated from O-2(+) reacting with water vapor in a duct. The O-2(+) ions are generated by a strong ionization dielectric barrier discharge and then injected into the duct. Compared with conventional gas discharge treatment, the present method does not need a plasma reaction reactor, additional catalysts, reductants, or oxidants. The main recovered products are the liquids H2SO4 and HNO3, which can be used in many processes. Removal rates of 97% for NO and 82% for SO2 are obtained under the following optimal experimental conditions: molar ratio of reactive oxygen species (O-2(+), O-3) to SO2 and NO, S; inlet flue gas temperature, 65 degrees C; reaction time, 0.94 s; and H2O volume fraction, 8%. Production of O-2(+) and the plasma reaction mechanisms are discussed, and the recovered acid is characterized. The experimental results show that the present method performs better for denitrification than for desulfurization. Compared with conventional air discharge flue gas treatments, the present method has lower initial investment and operating costs, and the equipment is more compact.