【作者】 王百荣；

【导师】 张连水；

【作者基本信息】 河北大学 ， 原子与分子物理， 2009， 硕士

【摘要】 SO2作为重要的大气污染气体,主要来自于燃煤锅炉的排放。伴随其排放含量较高的气体是氮气和水蒸气,此外还有CO和CO2,所以研究脉冲放电脱除SO2的动力学过程,必须考虑氮气和水蒸气的影响。除此之外,脉冲放电等离子体特性也直接关系着SO2的脱除效率。本文采用荧光发射光谱方法,研究了脉冲放电的特性参数、水分子的激发解离,以及SO2的激发过程,得到了创新性研究成果。本文首先对掺有痕量Ar的大气压N2气脉冲放电等离子体特性进行了实验研究。依据荧光谱线强度正比于粒子数分布原理,借助于Ar不同激发电子态跃迁荧光强度,采用谱线相对荧光强度比值法和玻尔兹曼曲线斜率法,对脉冲流光放电和介质阻挡放电(DBD)等离子体的电子激发温度、电子密度进行了实验测量。结果表明：由玻尔兹曼斜率法所得脉冲流光放电和DBD放电等离子体的电子激发温度分别为(7474±500)K和(4041±400)K,均高于相对荧光强度比值法所得电子激发温度(6725K±1500K和3887K±1500K)；两种放电等离子体的电子密度分别为15.76175×1015cm-3和10.35165×1015cm-3；两参数的空间分辨测量结果与气体放电理论推测很好的符合。其次对标准大气压下H2O分子脉冲放电等离子体激发解离动力学过程进行了实验研究。得到了H2O的脉冲流光和DBD放电荧光发射谱,将强荧光谱线归属为N2(C3Πu→B3Πg)、OH(A2Σ+→X2Π)、Hα辐射跃迁,最大区别是DBD放电中没有出现Hα辐射；对脉冲流光中N2337.2nm、OH308.4nm、H656.5nm荧光谱线时间分辨测量结果表明,OH*和H*荧光信号分别滞后N2*7.4ns和17.6ns,推断H2O的主要激发解离通道为：H2O与高能电子发生非弹性碰撞激发,解离成激发态OH和基态的H；空间分辨测量表明,在距负电极0.5mm附近活性粒子浓度最高,正好对应流光放电的负辉区。通过分析SO2脉冲流光放电荧光发射光谱,将237.3nm和330nm、370nm、430nm处光谱弥散包络分别归属为SO自由基A3Π→X3Σ和SO2分子B1B1→X1A1、A1A2→X1A1、α3B1→X1A1的荧光辐射跃迁；少量氧气条件下SO2脱除包括氧化和还原两种通道,产物分别是SO3和S原子。其中SO自由基是SO2脱除过程中的重要中间产物,主要是通过高能电子将SO2分子直接离解或激发至高电子激发态后离解生成。更多还原

【Abstract】 As a significant atmosphere pollutant, SO2 mainly come from exhaust of burning coal boiler. Besides CO and CO2, N2 and H2O are also high content gas produced in this process. So the study of kinetics process of removal SO2 by pulsed streamer discharge must take the influence of N2 and H2O into account. Besides, the characteristic of pulsed streamer discharge plasma directly concern the removal efficiency. The methods of the fluorescence emission spectrum are used to study the characteristic parameter of pulsed streamer discharge、the excitated and dissociation process of H2O and the dissociation process of SO2. Through the experiment, we find some innovative production.First, N2 plasma characteristics in pulsed streamer discharge at atmosphere pressure is studied by using trace Ar dispersion fluorescence spectrometry method. According to the elements of fluorescence spectra intensity direct ratio to particle distribution, recuring to the different excited state fluorescence spectra intensity, plasma electron excited temperatures and electron density of pulsed streamer discharge and dielectric barrier discharge are obtained using relative fluorescence intensity ratio method and Boltzmann plot method. This fact shows that the calculated plasma electron excited temperature from Boltzmann plot method are (7474±500)K and (4041±400)K,which are both higher than the electron excited temperature from relative fluorescence intensity ratio method, (6725±1500)K and (3887±1500)K. And the electron density are 15.76175×1015cm-3 and 10.35165×1015cm-3 respectively. The fact also indicate that pulsed streamer discharge plasma and dielectric barrier discharge plasma approximately the state of local thermodynamic equilibrium(LTE).Secondly, we study the excited dissociation kinetics of H2O gas in the pulsed streamer discharge plasma at the atmospheric pressure. The main spectrums detected in the experiment are assigned to C3Πu→B3Πg for N2、A2Σ+→X2Πfor OH radical and n=3→n=2 for H atom respectively. The temporal-resolved measurements at 337.2nm,308.4nm、656.5nm show that the occurrences of OH* and H* are later than that of N2* for 7.4ns and 17.6ns respectively. So dissociation process of H2O can be described as H2O is excited to high vibrational level of first excited state by non-elasticity collision with electron, and then dissociates to OH radical at excited state and H atom at ground state. Furthermore, the results of spatial-resolved measurements show that the densities of active particles reach the maximum at 0.5mm away from negative electrode corresponding to the negative glow region of streamer discharge. In the end, through analyze the pulsed streamer discharge spectrum of SO2,the spectrums of 237.3nm,330nm、370nm and 430nm detected in the experiment are assigned to A3Π→X3Σfor SO radical、B1B1→X1A1, A1A2、α3B1→X1A1 for SO2,respectively. Under comdition of little O2, SO2 could be removed through oxidation reaction and reduction reaction, and final products are SO3,S, respectively. SO radical is the key middle product in the process of SO2 removal. SO radical could be produced through direct dissociation and dissociation via electronic excited states of SO2 by high energy eletrons.更多还原