Flue Gas Desulfurization By Corona Discharge With Aqueous Catalytic

S02 emitted from various sources are the major cause of acid rain and photochemical smog. There is a vital interest in controlling these emissions in the near term for acid rain and in the long term for greenhouse effect. In addition, control of these emissions has now become an international issue, because of the adoption of increansingly more stringent emission standards. Among the novel technoligies for SO2 control, nonthermal plasma (NTP)-based proscesses are gaining an increaseingly important role. NTPs are conveniently produced by corona discharges in a gas at room temperature and pressure. Corona discharge is energy efficient because a large amount of energy goes into the production of energetic electrons rather than into gas heating, and the performance is good due to the large ionization region, which is used to remove sulfur dioxide in gas. In this paper, the corona discharge combined with aqueous catalytic technique is studied. The aim of the thesis was to simulate the interaction process between free radicals and SO2 and the transformation of SO2 under artifical conditions. The SO2 removal mechanisms was also discussed. The main conclusions of the research were as follows:1. Bromphenol blue (BPB) could capture the hydroxyl radical produced by Fenton reaction, changing its color from violet to achromatic. The effect of discharge voltage on generation of·OH radicals in a water film corona discharge system were experimentally investigeted using probe compound method taking BPB as the probe compoud. The results showed that the discharge voltage has directly influenced on·OH emission, and·OH production increased with discharge voltage increasing. Kinetic studies showed that the data were well described by the pseudo-first-order kinetic model.2. The voltage-current characteristics of corona discharge in a wire-cylinder reactor for flue gas desulfurization (FGD) was investigated. The effects of voltage, water flow rate, Mn2+ and SO2 concentration on the efficiency of FGD were investigated. The reaction process of the FGD by corona discharge combined with Mn(Ⅱ) was discussed primarily. The results showed that the removal efficiency of FGD was increased with increasing of voltage, water flow rate and Mn2+ concentration, and was not influenced remarkably by SO2 concentration. The sulfur dioxide oxidation process can be enhanced by corona discharge with Mn2+aqueous catalytic, and resulted in increaseing the efficiency of desulfurization. It was a very complicated system that included reaction process of the FGD by corona discharge combined with Mn(Ⅱ), which included electro-migration, gas-liquid mass transfer, aqueous catalytic.3. A mass-transfer efficiency model of the process for flue gas desulfurization by corona discharge with liquid film was provided, including gas bulk migration, liquid phase transfer and chemical reaction. The equations of the desulfurization efficiency and rate of flue gas, discharge voltage, reaction enhancement factor and film thickness were established. It was found that the conditions of discharge voltage and enhancement factor increased, desulfurization efficiency could be remarkably increased. The effect of varying film thickness (liquid phase's turbulent motion) was seem to be minimal. The experimental results were in agreement with the model.4. In order to explain the experimental observations, we proposed a simplified SIE chemical kinetic model for discussing flue gas desulfurization by corona discharge with aqueous catalytic. The experimental results showd that the corona discharge increased the mass transfer in the gas phase; SO2 absorption and conversion accords with SIE kinetic model; when the discharge volatge is 15 kV, the energy constant for water, NaOH solution and Mn2+ solution were 0.06318 Nm3·kJ-1,0.21275 Nm3·kJ-1 and 0.1309 Nm3·kJ-1,respectively. With increasing of the discharge voltage, the corona discharge will play a key role in the whole process.