Mass transfer enhancement by corona discharge and mercury capture by in-situ aerosol formation.

摘要

The absorption of SO₂ from the gas mixtures of SO₂/N ₂ into deionized water was measured under corona discharge at 22°C and 1 atm. A model based on film theory was developed to evaluate the effects of mass-transfer enhancement in the liquid phase by chemical dissociations and corona discharge current. It has previously been reported that mass transfer in the gas phase is enhanced by the corona discharge. In this study, it was also found that corona discharge enhances the mass transfer in the liquid phase through liquid-side boundary-layer thinning caused by corona-induced surface vibrations. The liquid boundary layer decreases as the corona power is increased. For our experimental conditions, mass transfer was enhanced by about 5.5 times in the gas phase and about 2.3 times in the liquid phase.; The absorption of SO₂ from the gas mixture of SO₂/air into tap water was measured under pulsed corona discharge at 22°C and 1 atm as a continuation of the previous study. The mass-transfer enhancement in the gas phase showed almost the same trend as that obtained from a gas mixture of SO₂/N₂ and deionized distilled water. Meanwhile, as the corona power increases, the effect of mass-transfer enhancement due to chemical absorption in the liquid phase for the absorption of SO₂ /air into tap water was attenuated in comparison with that for the absorption of SO₂/N₂ into deionized distilled water.; A lab-scale experimental apparatus was used to investigate mercury removal using in-situ generated aerosol particles from a simulated flue gas containing 10–40 ppb of gaseous elemental mercury at 178°C. This operating temperature was chosen to represent the flue gas temperature after the air preheater in a typical power plant. The particles, mostly ammonium sulfates as confirmed by X-ray diffraction, were generated by the gas-phase reaction of SO₃ and NH₃ by maintaining 20–50 ppm SO₃ with NH₃/SO₃ molar ratio of 2. The generated particles were captured by the glass-fiber filter which was also maintained at 178°C. The results showed that as high as 49% of elemental mercury was captured by the particles.