【作者】 魏林生；

【导师】 岑可法； 周俊虎；

【作者基本信息】 浙江大学 ， 工程热物理， 2008， 博士

【摘要】 为了在保证效率、满足日益严格的环保标准的前提下，取得更好的经济性和系统与操作的简化，国际上提出了燃煤污染物联合脱除的思路，期望用较少的设备脱除尽可能多的污染物。最新的商业和工艺发展成就显示了臭氧氧化技术，除了脱除NOx外，还提供了更好的灵活性，能作为一个独立的工艺或者与其他技术结合开发经济的多污染物控制工艺。本文就臭氧氧化结合化学吸收联合脱除烟气多种污染物工艺中臭氧产生能耗大这一关键性问题进行深入研究。对高频高压介质阻挡放电产生臭氧进行实验研究并整理了各种情况下低温等离子体化学反应机理．氧气源时，在臭氧产率相当的情况下，臭氧浓度和产量均为商用产品的2倍左右。对于惰性气体为He的情况，O₂→O₃转化率随O₂的比例增大而增大；对于惰性气体为Ar的情况，空气源时O₂→O₃转化率随O₂的比例增大而增大，氧气源时O₂→O₃转化率随O₂的比例增大而减小。对于惰性气体为Kr的情况，O₂→O₃转化率随O₂的比例增大而减小。对于干空气中添加少量的SF₆有利于臭氧产生，在流量为200l/h、输入电压为250V、SF₆／干空气=2．04×10^-2时，臭氧浓度提高到2．35倍（11．3 g／m³）。为获得高浓度、大产量、性价比低的臭氧发生器开辟一条新途径。对脉冲放电进行实验研究。研究发现正脉冲有利于臭氧产生，因为正脉冲比负脉冲流光传播更长的距离，产生更多的分支和更多的流光通道，因此反应区域更大，从而促使更多的臭氧产生。正脉冲降低接地极附件（电场强度较低）二次电离发生，推迟了击穿的发生。另不同的电压输入方式也造成不同的起火电压．实验中氧气源和干空气源臭氧浓度最高分别为83．6 g／m³和40．9 g／m³，臭氧产率最高分别达到985．03 g／kWh和288．26 g／kWh，臭氧产量最高分别为19．15 g／h和5．33 g／h。研究结果表明：脉冲放电是一种比较有前途的臭氧发生形式。在Buntat研究基础上对量纲分析方法在脉冲等离子体臭氧产生领域进行深入试探和修正。依据∏定理推导出臭氧浓度和主要影响参数之间的关系式（参数包括峰值电压、电晕起始电压，间隙宽度，介电常数、压力、气体流速和放电室长度或脉宽）。该理论可以用来预测臭氧浓度和调查影响脉冲流光放电各参数的重要性。正、负脉冲导致不同的电压起始电压，该理论也可以确定极性对臭氧产生的影响。对各臭氧发生技术进行对比，对比发现我们研究的高频高压放电臭氧发生技术以及脉冲放电臭氧发生技术都能有效的大幅度地提高臭氧浓度和臭氧产率。在利用高频高压放电产生臭氧时，空气源中添加SF₆臭氧发生的能耗占总的发电比例1．68％。而利用第3章的研究成果，在干空气源的情况下单通道和双通道的能耗分别占总发电比例的0．42％和0．64％．臭氧氧化技术在达到同等脱硫率和脱硝率，且脱汞率远大于电子束的同时，高频高压放电干空气源（SF₆）和脉冲放电单通道干空气源的耗电成本比电子束分别节省71．1％和92．7％。更多还原

【Abstract】 Changes in the structure of the electric utility industry are driving additional reductions of multiple pollutants. Control technologies that are capable of simultaneously reducing emissions of multiple pollutants may offer the potential to achieve this at lower cost and reduced footprint when compared to conventional controls. Recent commercialization and process development efforts have revealed that the ozone oxidation process offers additional benefits beyond its ability to simply remove NOx. These benefits result from the variety of ways the process can be installed and operated, and as consequence, ozone oxidation offers a degree of flexibility not available with processes such as SCR. This paper explores the key question for the simultaneous removal of multiple pollutants by combined ozone oxidation and chemical scrubbing: the high energy consumption of ozone.This paper experimental research on high frequency dielectric barrier discharge ozone generation, and collect the chemical reaction mechanism for different conditions. There are twice as many ozone concentration and ozone yield as business ozone generator. The effect of adding different admixtures to the feed gas were key-point investigated. The addition of impurities He to the oxygen feed gas and the dry air feed gas is shown to inhibit ozone generation. The O₂→O₃ global rate coefficient increases with increasing dry air proportion using mixture of dry air with Ar. In contrast, the O₂→O₃ global rate coefficient decrease with increasing O₂ proportion using mixture of oxygen with Ar. Using Kr as admixture, an increase in the O₂→O₃ global rate coefficient for ozone generation has been observed for increasing concentrations of added gaseous impurity into oxygen or dry air. The addition of even a small amount of impurity SF₆ has been shown to increase the energy yield of ozone, the ozone concentration improve by 2.35 times （11.3 g/m3） at 200 l/h, SF₆/dry air=2.04×10^-2. It offers a new way to obtain high concentration, large yield, high performance-price ratio ozonizer.Ozone synthesis by employing a short duration （-400 ns） of pulsed power with a dielectric barrier employing parallel plates was discussed. The positive pulse has been shown to be very effective for pulsed ozone production, as the streamers propagate to longer distances, and hence, the volume of the reaction zone will be larger, leading to more production of O₃ with more streamer channels per length than using the negative pulse, positive-negative pulse and negative-positive pulse. The positive polarity also trends to postpone the development of the breakdown of the gap due to lower secondary ionization emission from the negative electrode, where the electric field is lower. The difference input voltage waves induce difference corona inception voltage, too. The highest ozone concentration, ozone output and ozone production yield are 83.6 g/m³,19.15 g/h, 985.03 g/kWh in oxygen, and 40.9 g/m³,5.33 g/h, 288.26g/kWh in dry air, respectively. The experiment results show that ozone production by pulsed streamer non-thermal discharges is very effective without significantly raising the gas temperature or inducing arc breakdown between the electrodes at room temperature and atmospheric pressure.This paper put forward the application of dimensional analysis to ozone production by pulse streamer discharge, and dealt with the relation between ozone concentration and most prominent parameters. In this study, the influence on the ozone concentration of the pulse repetition frequency, difference of the peak pulse voltage and the corona inception voltage, gap length, relative permittivity, pressure, gas flow rate and reactor length （or pulse width） have been investigated by means of dimensional analysis. Positive and negative voltages are known to lead to different corona inception voltages, and the formula may be an applicable approximation method for the estimation of the effects of polarity on the ozone concentration through inserting the appropriate voltage into formula. The general trend of the concentration of ozone on parameters that are of importance in its design agrees with the experimental results to confirm the validity of the model.According the research results in chapter 2, the power requirement for ozone generation using dry air with admixture SF₆ is projected to be approximately 1.68 percent of the gross power output. According the research achievements in chapter 3, using single channel mode and double channel mode in dry air, the power requirement are 0.42 and 0.64 percent of the gross power output, respectively. The low temperature ozone oxidation technology can achieve the same NOx and SO₂ removal as electron beam technology, and high efficiency removal of HCl, HF, Hg and some other pollutants. Energy consumption by high frequency and high voltage in dry air with admixture SF₆ and pulsed discharge in dry air are 71.1% and 92.7% less.更多还原