【作者】 王沈兵；

【导师】 骆仲泱； 岑可法；

【作者基本信息】 浙江大学 ， 工程热物理， 2011， 硕士

【摘要】 脉冲电晕放电烟气净化技术是新兴的烟气多种污染物协同脱除手段。脉冲电晕放电污染物脱除过程中,OH自由基的生成特性及其影响因素和NO的空间分布特性及其多种影响因素的研究将为脉冲电晕放电多种污染物协同脱除技术的优化及应用提供技术参考与支持。本文分别利用发射光谱法及激光诱导荧光法对脉冲电晕放电等离子体中OH自由基及NO进行了检测,主要研究如下：为更深入地认识线-板式脉冲电晕放电反应器的性能,以发射光谱为基础检测到了OH(A2∑+→X2П)的光谱,证实了脉冲电晕放电中OH自由基的存在。研究了常压下脉冲电晕放电OH自由基的空间分布特性、线电极形式、线线及线板间距以及氧气含量对OH自由基生成的影响。结果表明：OH自由基数量在线电极X轴方向越来越少,活化区域半径大致为20mm,Y轴方向先变大后变小,活化区域大于30mmm,Z轴方向基本不变；线电极直径在较小范围内变化,OH自由基光谱强度变化较小,直径大于2mm,光谱强度随着直径增大急剧下降。随着线板间距的变大,OH自由基的发射光谱强度随之降低。OH自由基的发射光谱强度随着线线间距的增大而增强。随着氧气含量的增大而明显变少,特别是氧气含量大于10%以上,OH自由基的发射光谱在309nnm处的峰值基本消失。利用发射光谱研究了常压下线板式脉冲电晕放电NO脱除过程的NO(A2∑,0)→NO(X2П,2-6)发射光谱,主要研究了其发射光谱强度的空间分布特性以及NO浓度等因素的影响。NO的发射光谱谱线随着放电峰值电压、脉冲频率的增大而增强。然而频率在较高范围内变化时,NO的谱线强度变化非常小NO的发射光谱强度随着背景气体中NO浓度的降低明显减弱。对于浓度低于200ppm,谱线基本消失。NO发射光谱谱线主要集中在线电极X轴方向10mm半径区域内,Y轴方向10mm半径区域,超过这个区域基本检测不到NO的光谱信号。实验仅定性反映激发态NO的空间分布,要精确研究NO脱除过程的时空分布必须选择新的检测方式。由此可知,激发NO跃迁所需能量比OH自由基要高。以激光诱导荧光技术为基础研究了常压下脉冲电晕放电OH自由基的空间分布特性以及氧气含量对其生成的影响。通过实验数据的分析以及探讨,得出了以下结论：OH自由基距线电极X轴方向上各点相对浓度有变小的趋势,但变化不大,分布区域大于30mm。然而距Y轴方向10mm内,OH自由基的浓度变化趋势为先增大后减小,浓度最大的区域集中在纵向5mm附近,超过此区域OH自由基浓度迅速减少。OH自由基浓度随着氧气浓度的增加,先变大后变小,且当氧气浓度为10%左右的时候OH自由基浓度最大,氧气浓度大于40%时,OH自由基基本消失。由于选择10%左右的氧气含量能够产生最多的OH自由基,所以进行烟气污染物脱除过程的氧气含量可以选择此工况。更多还原

【Abstract】 Pulsed corona discharge is a new technique for multi-pollutants removal in flue gas. In the process of pulsed corona discharge, the OH radical production; the spatial distribution of NO in the electric field and correlative are discussed in detail, and to support the research of the technology for the removal of multi-pollutants by pulsed corona discharge as references. The emission spectroscopy and laser-induced fluorescence techniques have been used to diagnose the OH etc. active species produced by pulsed corona discharge at atmospheric pressure. The main results presented in the dissertation have been summarized as follows:In order to get extensive knowledge of wire-to-plate pulsed corona discharge reactor, emission spectrums of OH(A2Σ+→X2Π) is detected in humid Ar pulsed corona discharge, the existence of OH radical in pulsed corona discharge is verified. The influence of different diameters of wire electrode, different wire-to-plate and wire-to-wire spacings, OH radical generations in different O2 concentration were experimentally investigated under atmospheric pressure based on emission spectrum, the spatial distribution of OH radicals in the electric field is also discussed in detail. The results showed that:OH radicals decrease along the X-axis, the radius of active volume is approximately 20mm; showed a trend of first increase and then decrease along the Y-axis, the activation radius is more than 30mm; in the direction of Z-axis, no essential difference occurs. OH radical has small change as the diameter of wire electrode is shorter than 2mm; with a sharp decline as the diameter continue to increase. OH radical emission intensity decreases as wire-to-plate spacing increasing, increases as wire-to-wire spacing increasing and decreases as O2 concentration increasing.The emission spectrum of NO(A2Σ,0)→NO(X2Π,2-6) produced by pulsed corona discharge in a wire-to-plate electrode configuration has been recorded. The influence of the peak voltages, the discharge frequencies, the NO concentration on the emission intensities are investigated. The spatial distribution of NO in the electric field is also discussed. Experiments’results proved the emission intensity of NO increases as the peak voltages and frequencies of pulsed corona discharge increasing. The emission intensity of NO has small change as the frequencies of pulsed corona discharge changes in higher range. The emission intensity of NO decreased significantly as the NO concentration decreasing, and disappeared as the concentration less than 200ppm. The emission spectrum of NO focused on the 10mm radius of the region along the X-axis and Y-axis, and NO fluorescence signal disappeared over the region. This experiment can only reflect the spatial distribution of excited NO, new detection methods must be selected to accurately know the spatial distribution of NO. It is found that the energy needed to stimulate the NO is higher than the OH radical.To study the spatial distribution of OH radicals and the influence of different O2 concentration on OH radical generation were experimentally investigated under atmospheric pressure based on laser-induced fluorescence. It is found that OH radicals decreasing along the X-axis, the activation radius is approximately 30mm; showed a trend of first increase and then decrease along the Y-axis, the activation radius is 10mm; and OH fluorescence signal disappeared over the region. OH radical concentration showed a trend of first increase and then decrease as oxygen concentration increasing, the largest OH concentration appear when the oxygen concentration is 10%, and OH radicals disappeared when the oxygen concentration greater than 40%. Select about 10% of the oxygen content can produce the most OH radicals, so we can choose the working condition as multi-pollutants removal in flue gas.更多还原