【作者】 吴晓东；

【导师】 张芝涛；

【作者基本信息】 大连海事大学 ， 环境科学， 2005， 硕士

【摘要】 随着我国机动车保有量的增加,内燃机尾气对大气造成的污染越来越严重。由于目前普遍使用的催化转化法脱除NOx的效果不理想且会对环境造成二次污染,因此许多学者开始致力于等离子化学法的研究。本文结合国家自然科学基金重点资助项目（项目编号:60031001）以及交通部重点科技项目（项目编号:95-06-02-19）,针对当前等离子体化学法治理内燃机尾气NOx存在的主要问题,提出采用强电离放电手段,实现在分子层次上将O₂和H₂O电离、离解成高浓度强氧化自由基,进而将内燃机尾气中的NOx氧化成HNO₃以达到脱除的目的。 本研究分三个层次进行: 1.利用带有透明电极与可侧向观察的DBD装置对其辐射特性进行了研究。结果表明:DBD的辐射特性受激励电压、激励频率、DBD结构等多种因素影响。采用窄间隙薄电介质层结构DBD在频率为10～20kHz高压电源激励下可以大幅度提高放电空间的电场强度,增加放电功率密度,提高放电装置性能,为在常压条件下实现大空间强电离放电提供了一种有效方法; 2.采用窄间隙薄α—Al₂O₃电介质层,结合高频高压激励电源构建了等离子体源;并解决了等离子体发生系统的谐振问题,大幅度提高了放电间隙电场强度,实现了大气压条件下的强电离放电; 3.对强电离放电脱除模拟内燃机尾气NOx的实验结果表明:NOx脱除率受激励电压、含氧量、含水量、NO原始浓度以及气体流量等多种因素影响。通过改进等离子体源、增设加湿装置以及改善气体混合装置等手段,在气体流量为10L/min,NO原始浓度为800×10^-6（v/v）条件下,NOx脱除率达到82.7%,远远高于传统的等离子化学法脱除NOx的水平。更多还原

【Abstract】 Pollution of diesel-engine exhaust is getting worse with increase of the number of vehicles in our country. Because catalyst method usually used doesn’t remove NOx well and can bring secondary pollution, many scholars begin to study plasma chemistry method. Considering the key problems of current research of reduction of diesel-engine exhaust NOx with plasma chemistry method, it is brought forward that strong ionization discharge method ionizing and decomposing O2 and H2O into high concentration active radicals on a molecular scale, then oxidizing NOx into HNO3, which is based on the key NSFC Project (No.: 60031001) and the key project of ministry of communications. (No.: 95-06-02-19)The paper is divided into three parts:1. The radiation of DBD plasma is studied at atmospheric pressure in its device with a transparent electrode and an observed side section. As a result, the applied voltage, applied frequency and the configuration of DBD can effect on its radicalization. Some methods, including the narrow discharge gap and thinner dielectric layer, high-frequency high-voltage power supply, were used in the micro-gap DBD at atmospheric pressure. These improvements are very helpful in increasing the electrical filed strength and power density in discharge gap of DBD. Thereby, it is a useful means for accomplishing strong ionization discharge at atmosphere pressure.2. Plasma source is designed by using the narrow discharge gap and thinner a-Al2O3 dielectric layer and high-frequency high-voltage power supply. Then resonance of DBD system is resolved. These improvements are very helpful in increasing the electrical filed strength and ionization region in discharge gap of DBD. As a result, strong ionization discharge is accomplished at atmosphere pressure.3. The results of strong ionization discharge remove NOx are shown as following: Influence of removal efficiency of NOx by several factors such as applied voltage, oxygen concentration, H2O concentration, primary concentration of NO, gas flow et al.is discussed. Through improving plasma source and gas mixing device, adding watering device, when gas flow is 10L/min, the primary concentration of NO is 800×10-6(v/v), removal efficiency of NOx is 82.7%, which is much higher than that of traditional plasma chemical method.更多还原