High-power short pulsed corona: investigation of electrical performance, SO/sub 2/ removal and ozone generation

Visual appearance, electrical performance and chemical activity of a 50 MW, 100 kV, 22 ns pulsed corona (PC) was studied in simulated air-SO/sub 2/ gas mixture in a coaxial reactor. Infrared and mass spectrometers and electrochemical sensors were used for gas diagnostics; solid byproducts were identified using X-ray fluorescent spectrometry. Electro-chemical methods of gas diagnostics were not sufficiently reliable in view of the cross-influence of different gases, especially in ozone presence. The removal efficiency of SO/sub 2/ both in dry air-SO/sub 2/ mixture and in humid atmosphere at room temperature and at 70/spl deg/C was studied. The removal efficiency of SO/sub 2/ decreased at lower pollutant concentration and higher frequency, while the pulse energy was kept invariant. Removal efficiency in dry mixture was 25 g/kWh; in humid air, it was several times greater, which is attributed to the influence of OH radicals. In dry SO/sub 2/-air mixture, the removal efficiency was much higher at positive polarity. Traces of many compounds were found and identified in treated gas. Ozone was produced in large concentrations both in dry air and in air-SO/sub 2/ gas mixture with or without water presence. Dependence of its formation rate on the pulsed and average power, and on the polarity of the pulses was studied. The precipitation of a yellowish powder identified as sulfur was observed. It is ascribed to direct breaking of atomic bonds of the SO/sub 2/ molecule by energetic species and confirmed by the experiments with dry N/sub 2/-SO/sub 2/ and Ar-SO/sub 2/ mixtures. This effect was not previously noted in literature. PSpice-based engineering model of corona-generator system is outlined. It was found that preliminary simulation results are in fair agreement with experimental data.