Effect of CO₂ and Water Vapors on NO_x Removal Efficiency under Conditions of DC Corona Discharge in Cylindrical Discharge Reactor

Abstract

Carbon dioxide (CO2) and water vapors effects on NO x removal efficiency was studied in the wire-cylinder discharge reactor utilizing a DC power supply. The content of CO2 in both wet and dry aired initial gases was 0%, 5%, 10%, 15% and 20%, respectively. NO x treatment efficiency strongly depended on a DC positive corona discharge mode, which changed with CO2 concentration regardless the water content. A glow mode of corona discharge, established when the concentration of CO2 in the initial gas was 0% and 5%, exhibited very low removal efficiency (removal rate under 10% and energy yield about 1.1 NO g/kWh). In the cases of 10%-, 15%- and 20%-content-of-CO2 input gas, the glow corona mode was transferred into a streamer for both wet and dry initial gases. Therefore, the removal efficiency dramatically enhanced–the most efficient treatment was achieved when 15% of CO2 was included in the initial gas (5.1 NO g/kWh for wet gas and 4.8 NO g/kWh for dry gas). Water vapors played an important role in NO2 removal via the mutual reaction forming HNO3. Therefore, in the wet-air supplied reactor the highest removal rates of NO x were as high as 48%, while in dry-air supplied reactor only 15%.

Optical emission study of nonthermal plasma confirms reaction mechanisms involving neutral rather than charged species

“…This way, the streamer propagates from the anode to the cathode, while electron drift is in the reverse direction. The streamer tip is called the streamer head ͑ionization region͒, while the streamer tail is called the streamer channel ͑electron drift region͒, 78 as shown in Fig. 7.…”

Effect of Coexisting Gases on NO Removal Using Corona Discharge

“…They were remarkably observed when only CO 2 was added to the base gas. There is a report (8) that the state of electrical discharge was changed greatly in the case of positive corona discharge when both H 2 O and CO 2 were contained in a gas, and many active species were formed and contributed to the NO removal. In the negative corona discharge, chain-like radiant spots appeared on the center electrode.…”

CHARACTERIZATION OF THE CHEMICAL BEHAVIOR OF A DBD WIRE-CYLINDER REACTOR FOR NOx REMOVAL. DETERMINATION OF REACTIONAL PATHWAYS BY ISOTOPIC LABELING

“…The oxidant vector can be O 2 (giving O in the discharge) [12] , CO 2 (giving O and CO) [13,14] and H 2 O (giving OH) [15,16,17] . Those species are present in excess in the mixture (about 100 to 1 NO molecule).…”