De-NOx by bidirectional pulse corona discharge

Summary form only given, as follows. For environmental pollution control, various discharge/plasma reactors have been developed. The unidirectional pulse discharge has been usually used for de-NOx or de-SOx studies but the sufficient decomposition efficiency have not been obtained. In this study, to use high-energy electrons effectively, de-NOx by bidirectional pulse corona discharge was investigated. An experimental device is made of 110-mm diameter, 340-mm high stainless steel cylindrical chamber, in which a wire electrode of 0.5-mm diameter is installed. To make a corona discharge a bidirectional voltage pulse is injected into the wire electrode. The bidirectional pulse was generated using a cable (RG-8U, 52/spl Omega/) discharge. The cable was charged to 20 kV initially and then discharged. The 10 kV pulse from the cable was stepped up to 40 kV by a pulse transformer. The reaction chamber was maintained at atmospheric pressure with an examination gas which is made of 250 ppm NO diluted in N/sub 2/ gas. For comparison, the decomposition efficiencies of NOx were measured using the bidirectional and the unidirectional discharges under the condition that the time integral of absolute applied voltages are the same. For the bidirectional pulse discharge, a cable of 20 m was used, so that the pulse widths were 100 ns for positive and successive negative pulses and for the unidirectional pulse discharge, cables of 10 m and 20 m were used so that the pulse widths were 100 ns and 200 ns, respectively. The repetition rates of discharge were 5 Hz for bidirectional pulse and unidirectional pulse of 200 ns, and 10 Hz for unidirectional pulse of 100 ns. The experimental results will be presented.