Improvement of NOx removal efficiency using atomization of fine droplets into corona discharge

Non-thermal plasma technique has a great possibility of realization for pollution control but there is a big problem about poor energy efficiency for exhaust gas treatment, especially NOx removal. This poor energy efficiency can be taken into account for the dynamic equilibrium existing between NO and higher nitrogen oxides such as NO2, NO3, etc. in the plasma zone. In order to improve the NOx removal efficiency, we tried to absorb the higher nitrogen oxides into the fine aqueous droplets atomizing into the discharge plasma area. The aqueous fine droplets were produced by electrostatic spray or nebulizer and injected into corona discharge reactor that consisted of stainless wire and cylindrical tube. Improvement of NOx removal efficiency was observed via atomization of aqueous droplets of 200 μm or less in diameter into corona discharge plasma. Especially, remarkable enhancement of NOx removal was achieved with the fine aqueous droplets (10–30 μm) which were produced by the nebulizer. Furthermore NOx removal efficiency was promoted very much by the addition of hydrogen peroxide into fine aqueous droplets.