Study On Application Of SCR Facilitated Non-thermal Plasma Method For De-NO_x In Flue Gas

As the major pollution of coal-fired flue gas, nitrogen oxide (NOx) would pose huge threats to ecological environment and human beings. Non-thermal plasma technology cooperated with catalyst technology used for pollution removal has gained comprehensive attention for its fast reaction rate and non-secondary-pollution. Considering difficulty of denitration at low temperature and overcommit of catalyst, the present work put forward a new method, which combined non-thermal plasma oxidation and selective catalytic reduction for NOx removal at the low temperature.This research forced on studying SCR cooperated with surface discharge induced reactive oxygen species and SCR cooperated with corona discharge for NOx removal. In former, clean air was ionized when going through discharge reactor, and then they flew injected simulated flue.In the process of corona discharge, all the simulated gas flew though the plasma area. The simulated gas went into SCR reactor for NOx removal afterwards. The main contents and results were summarized as follow:(1) After electrical parameters optimization of plasma reactor, this study forced on the study of NO oxidation by active oygen species injection and corona discharge. The experiments demonstrated that O3 was the driver substance of NO oxidation in the injection of reactive oxygen species injection, while both O and OH radicals took part in NO oxidation in corona discharge.(2) In the process of active oxygen species injection, NO oxidation efficiency increased with applied voltage rising. With the condition of 120mm discharge length,15 mL/min air injection and 150℃ simulated gas, NOx oxidation efficiency achieved 50% at 2.7 kV.(3) In the process of corona discharge, NO oxidation efficiency would be significantly improved when H2O was added to the simulated gas. It attributed to OH radical generated from the ionization of H2O, which possesses high oxidation potential.(4) At temperature of 150℃, the efficiency of NOx removal by SCR facilitated non-thermal plasma was 23% higher than single SCR process. This was because NO was oxidized to NO2 firstly, then NO2 was adsorbed on the surface of catalyst and formed NO3-and NO,. On the one hand, NO; reacted with NH3 on the catalyst directly; on the other hand, acceleration of NO3 on V4+-OH re-oxidation enhanced catalyst activity furtherly at low temperature windows. In high-sulfur or high humidity simulated flue gas, NOx removal efficiency of SCR facilitated active oxygen species injection were improved 31.9% and 21.5% than the single SCR severally. In the process of SCR facilitated corona discharge, corona denitration would be conduted once water added, which was 53% higher than SCR solely. When NO2 was added to the simulated gas with high humidity, the NOx removal efficiency by SCR facilitated corona discharge was improved 60% than SCR solely.