Experimental Study On NO_x Removal Using Pulsed Corona Discharge With Knife-Edge-to-Plate Electrode

Removal of nitrogen oxides using pulsed corona discharge plasma technology has been one of the dry methods for flue gas denitrification since 1980s. Compared to other conventional techniques, this method has many merits, such as high removal efficiency, simple process, no secondary pollution, and so on. Therefore, many investigations have been focused on this field. However, this technology is only carried out in laboratories at present and still not acceptable for commercial use. There are a lot of factors that affect the removal of NO_X, but the matching between the electrode configuration of discharge reactor and high-voltage power supply plays an important part in the effective elelctric energy input and NO_X removal characteristics, so the matching between them is very important.In this study, a new type of knife-edge-to-plate electrode structure reactor is introduced. Firstly, the electrode configuration is carried out to examine its effect on the pulsed corona discharge characteristic, the effect of these factors like discharge electrode spacing, electrode shape, discharge electrode to plate spacing, pulse voltage, pulse repetition rate on the energy input is analyzed. On the basis of above experiments, combining the positive-pulsed high voltage, the effect of pulse peak voltage, pulse repetition rate, gas flow rate and initial NO_X concentration on the NO, NO₂ removal characteristics is also discussed. The main experimental results are summarized as follows:1. Electrode shape has a large effect on the discharge power input. Under the same condition, knife-edge-to-plate electrode structure has the better stabilization of discharge streamers, so its input power is higher;2. Reactor input power increases with increasing the pulse voltage, pulse repetition rate, at the same time, NO_X removal efficiency is enhanced;3. When wire-to-plate spacing is increased, both discharge voltage and pulse peak voltage are increased, which results in the reduction of the single pulse energy input and the discharge power. Under our experimental conditions, the optimal discharge electrode spacing is 40mm;4. Residence time of NO_X in the reactor decreases with increasing the mixed gas flow rate, which leads to the decrease of NO_X removal efficiency. When initial NO_X concentration increases, higher discharge voltage is required for obtaining the same removal efficiency;...