Corona discharge oxidation of sulfur dioxide

Abstract

~~Sulfur dioxide (500-3000 ppm) in a flowing humid air mixture was exposed t o a corona discharge in a wire-tocylinder reactor. Sulfuric acid mist was precipitated on the inside wall-electrode, and ozone and the remaining SO2 were monitored at the exit port. Residence times, humidities, oxygen, and SO, concentrations were varied to study the kinetics of the conversion of SO, to acid mist. The reaction was zero order with respect t o SO, in the range tested, and the ratedetermining step appeared to be the formation of atomic oxygen by the electrical discharge. Optimum reaction rates occurred at 70% r.h. and above 15% oxygen concentration. Studies of the precipitated droplets indicated a mean size of 6.36 before deposition.ulfur dioxide mixed with oxygen or air has been oxidized S in the presence of an electrical corona discharge by a number of investigators. Miklos et al. (1966) reported efficiencies on the order of 35 % for direct oxidation of SO, to SOs in a n airstream. Palumbo and Fraas (1971) concluded that a damped or pulsed high-frequency current was more effective than direct current for SOz conversion. In their tests the reactor was placed in a n oven at 130°C, and a conversion efficiency of 96% was obtained with a power expenditure of 9 W over a period of 30 min. In the absence of water vapor, only 67% of the SOs was converted. Reaction products were identified as elemental sulfur and sulfuric acid. The reaction mechanism was not studied. Moyes and Smith (1965) presented comparative results for the thermal-and electrical discharge-activation of mixtures of SO? and Os. They showed that the activation by electrical discharge was more efficient, but had doubts about its industrial application for exothermic reactions for which a suitable catalyst was available.Several questions as to the various reaction mechanisms in such a gas mixture exposed to a corona must be dealt with before launching into pilot scale studies. However, in the case of SO2, such information is useful especially in certain electrical precipitator operations. The generation of sulfuric acid mist in limited quantities, in power plant stack gases, may have the beneficial side effect of combining with and reducing the resistivity of some types of fly ash, thereby increasing the precipitator's efficiency. Overproduction of the mist, however, would initiate corrosion problems and decrease the overall performance of the precipitator in the long term. Reese and Greco (1968) have shown in tests with TVA precipitators that the presence of H2S04 mist seriously lowered the collection efficiency of electrostatic precipitators. Therefore, it is desirable to have a quantitative estimate of the extent to which various operating conditions in a corona discharge contribute to the conversion of SO, t o sulfuric acid mist. This paper treats several of the parameters influencing the SO? oxidation in a corona to include relative humidity, electrical potential, gas concentrations and flow rates; and reaction mechanisms are proposed, based on results of thes...

Absorption of sulphur dioxide by electrosprayed droplets

“…The negligible effects of droplet polarity has already been shown in previous works about experiments with large scale sprays. [11,[24][25][26] This result is consistent with the physical expectations regarding the chargedipole interactions occurring between the charged drop and the polar, uncharged, SO 2 molecule. In a first attempt, we extended Equation (1) to provide a semiempirical equation to describe the ratio Λ se / Λ s can be derived in the following form:…”

“…In addition, the corona generates an ionic wind mostly oriented toward the ground electrode of the corona charger. [16,[24][25][26]30,31] This further increased the depletion rate over the setup walls. The correlation between Λ we /Λ w and the corona current became faint for potentials higher than +10 kV.…”

The Fate of Vanadium in an Urban Air Shed: The Lower Delaware River Valley

“…Further consideration should be given to the part which corona discharge in electrostatic precipitators may play as a catalyst in SO2 to SO3 conversion. 13 Another field worth exploring will come from the increasing use of vanadium oxides as catalysts in the manufacture of such products as sulfuric acid 6 and phthalic anhydride from naphthalene, 11 and the resulting possibility of vanadium pollution by catalyst loss.…”

“…The reconciliation of the two approaches to residence time determination is found in the postulated formation of V2O5 -H 2 SO4 aerosols. Matteson et al 13 observed that H2SO4 aerosols, formed under electrostatic precipitator corona discharge catalysis averaged 6-7 fi. In our case, with a specific gravity of 1.0 and a 500 m fall, the aerosol diameter would be about 13 M to reduce the time of fall to 1 day.…”

Competition of NO and SO2for OH Generated within Electrical Aerosol Analyzers

“…Stelson's demonstration was supported by the results of Matteson et al (1974), who formulated the theory of "Sulfuric acid formation caused by oxidation of SO, in the Corona discharge." According to Matteson et al * Research performed at Atlanta University Center, Inc.…”