Patent ID: 7368094
Filing Date: 2008-05-06
Classification: B01D

Abstract:
1. A method of treating nitrogen oxides, comprising NO and NO 2 , in an exhaust stream from a lean-burn combustion source, the exhaust stream being at a temperature below 250° C., the method comprising: passing a stream of ambient air through intertwined helical regions of active and passive electric fields produced in a high frequency alternating current powered non-thermal plasma generator to produce a stream containing ozone, wherein the non-thermal plasma generator comprises a tube having a dielectric cylindrical wall defining a reactor space; a linear, high voltage electrode disposed along the axis of the tube; and an outer ground electrode spirally wound around the external surface of the dielectric cylindrical wall in an axially discrete pattern, and wherein the amount of ozone produced in the stream flowing through the annular space formed between the dielectric cylindrical tube and the central high-voltage electrode is proportional to the electrical energy applied to the generator; adding the ozone-containing stream to the exhaust stream to convert at least a portion of the NO content to NO separately adding to the ozone-containing exhaust stream a reductant for NO and NO passing the resulting exhaust stream into contact with a reduction catalyst for nitrogen oxides at a suitable space velocity for conversion of nitrogen oxide in the exhaust stream to nitrogen.