【作者】 樊磊；

【导师】 李济吾；

【作者基本信息】 浙江工商大学 ， 环境工程， 2011， 硕士

【摘要】 二氧化硫的污染和危害日益严重,已成为当前世界亟需解决的重要环境问题。低温等离子体技术在常温常压下放电能产生大量的高能电子和自由基,对二氧化硫等具有脱除效率高、反应速度快、无选择性等优点,是当今环保领域的研究热点。为了进一步减少等离子体脱硫的能耗,提高脱除效率,降低净化成本,本文提出将电晕放电等离子体与液相催化相结合脱硫方法。在深入认识自由基与二氧化硫反应及二氧化硫迁移传质的基础上,利用电晕放电等离子体技术与液相催化技术脱除模拟烟气中二氧化硫,并探索其脱除机理。主要研究结论如下：1.利用分光光度法,以BPB为探针捕捉剂,实验研究了在空气为背景气体下,不同电晕放电电压和放电时间下·OH自由基的产生情况。实验表明·OH自由基的产生量随放电电压增大而增大,与放电电压有较明显的关系。对液膜电晕放电产生·OH进行检测分析,并探讨其反应动力学过程。2.建立了线筒式电晕放电反应器,研究了其放电特性,以及电压、水流量、Mn2+浓度和SO2浓度等对电晕放电与Mn(Ⅱ)液相催化协同脱硫效果的影响,并探讨了协同脱硫的反应机理。结果表明,脱硫效率随着放电电压、水流量和Mn2+浓度的增加而增加,SO2浓度的影响不明显。电晕放电与Mn(Ⅱ)液相催化协同能够加强SO2的氧化作用,提高脱硫效率。电晕放电与Mn(Ⅱ)液相催化协同能够将SO2从气相状态转移到液相氧化成硫酸盐类,其间存在着电迁移、气液传质以及液相催化等过程。3.对液膜电晕放电烟气脱硫进行了传质反应过程分析,主要过程为气相主体迁移与液相扩散及化学反应。导出了烟气脱硫率与放电电压、化学反应增强因子以及液膜厚度的关系。发现在提高放电电压和增强因子的条件下,烟气脱硫率可以显著提高,而改变液膜厚度即液相的湍动对脱硫效率影响不大。所得结果与实验结果相符,单位能耗相对较低。4.根据自由基反应过程,推导出电晕放电协同液相催化脱硫的SIE动力学方程,并对实验结果进行曲线拟合。得出电晕放电产生的电场作用能够明显降低二氧化硫的气相传质阻力；二氧化硫的吸收转化符合提出的动力学模型；水溶液、NaOH溶液和Mn2+溶液在15kV放电电压下的能量系数分别为0.06318 Nm3·kJ-1、0.21275 Nm3·kJ-1和0.1309 Nm3·kJ-1。可见在15 kV条件下,NaOH溶液的能量系数是水溶液的3.37倍,是Mn2+溶液的1.63倍。而随着电压的提高,电晕放电在整个过程中将起到主导作用。更多还原

【Abstract】 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.更多还原