High-power short-pulsed corona: investigation of electrical performance, SO2 removal, and ozone generation

Visual appearance, electrical performance, and chemical activity of a 50-MW 100-kV 22-ns pulsed corona were studied in simulated air-SO₂ 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. Electrochemical sensors were employed for the measurement of initial concentration, before the discharge commencement. The removal efficiency of SO₂ in dry and humid air-SO₂ mixtures was studied. The removal efficiency of SO₂ decreased at lower pollutant concentration and higher frequency, while the pulse energy was kept invariant. Removal efficiency in dry mixtures was 25 g/kWh; in humid air, it was several times greater, which is attributed to the influence of OH radicals. In dry mixtures, 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 and humid mixtures. Dependence of its formation rate on the pulsed power, and on the voltage polarity was studied. The precipitation of a yellowish powder identified as sulfur was observed. It is ascribed to cleavage of bonds of the SO₂ molecule by energetic species and confirmed by experiments with dry N₂-SO₂ and Ar-SO₂ mixtures.