Effects of Discharge Polarity on the Fine Particle Formation from SO<SUB>2</SUB> by DC Corona Discharges

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  • NAGATO Kenkichi
    Department of Mechanical Engineering, Kochi National College of Technology
  • YOSHIZUMI Hitoshi
    Department of Mechanical Engineering, Kochi National College of Technology
  • NONAKA Yuya
    Department of Mechanical Engineering, Kochi National College of Technology
  • FUKAGAWA Kei
    Department of Mechanical Engineering, Kochi National College of Technology

Bibliographic Information

Other Title
  • 直流コロナ放電によるSO<SUB>2</SUB>からの微粒子生成に対する放電極性の影響
  • 直流コロナ放電によるSO2からの微粒子生成に対する放電極性の影響
  • チョクリュウ コロナ ホウデン ニ ヨル SO2 カラノ ビリュウシ セイセイ ニ タイスル ホウデン キョクセイ ノ エイキョウ

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Abstract

We have measured the effects of discharge polarity on the formation of fine particles from SO2 by DC corona discharges in order to study the role of gaseous ions in the desulfurization process of flue gases by using discharge plasmas. For both positive and negative discharges, the number concentration of the formed particles in SO2/H2O/Air mixtures increased with SO2 (0-1 ppm) and H2O (5 × 102-3 × 103 ppm) concentrations. However, the positive discharges produced a larger amount of particles, and the size of which was larger than those formed by negative discharges. The fraction of charged particles dropped significantly with increasing the number concentration of formed particles in the case of positive discharges, while large fractions of charged particles were observed for negative discharges under all conditions. Mass spectrometric measurements confirmed the formation of H2SO4 by negative discharges through the detection of HSO4- ions in the negative ion mass spectra . On the other hand, no positive ions of H2SO4 were found in the mass spectra of positive ions formed by positive discharges. However, the dominance of H3O+ ions in the spectra suggested that the formation of OH radicals and the subsequent formation of H2SO4 took place also in the case of positive discharges. Because of its high electron affinity, H2SO4 formed by negative discharges is easily ionized to HSO4- ions by the reactions with the surrounding negative ions, which leads to the charged particle formation via ion-induced nucleation. On the contrary, since H2SO4 hardly reacts with positive ions and remains neutral with positive ions, the most of particles are formed via homogenous nucleation by positive discharges.

Journal

  • Earozoru Kenkyu

    Earozoru Kenkyu 23 (2), 101-107, 2008

    Japan Association of Aerosol Science and Technology

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