船舶尾气臭氧氧化脱硝实验研究

发布时间：2018-01-16 14:01

本文关键词：船舶尾气臭氧氧化脱硝实验研究　出处：《大连海事大学》2017年硕士论文　论文类型：学位论文

【摘要】：目前,由于船舶尾气中含有大量的硫氧化物(SO_x)、氮氧化物(NO_x)、颗粒物(PM)等多种污染物,造成了日益严重的大气污染问题。国际海事组织制定并通过了MARPOL73/78公约附则VI,对废气中NOx浓度设定了明确的限值要求。为了满足排放标准,人们提出了选择性催化还原(SCR)、废气再循环(EGR)、湿法洗涤氧化、臭氧(O_3)氧化等多种不同的船舶尾气脱硝方法。其中O_3氧化方法具有脱硝效率高、原理简单等特点,具有良好的应用前景。本文初步研究了 O_3自分解特性,进而开展了 O_3氧化脱硝实验研究,最后初步研究了湿法洗涤对O_3氧化脱硝性能的影响及其作用机理。首先,实验研究了 O_3自分解特性。结果表明,烟气温度是影响O_3自分解的主要因素,随着烟气温度的升高,O_3自分解率增加。其中当温度小于100℃时,O_3自分解率缓慢增加,而当温度大于200 ℃时,O_3自分解率明显增加。当烟气温度为100 ℃时,随烟气停留时间的增加,O_3自分解率缓慢增加,不同O_3浓度对应的O_3自分解率的变化趋势基本一致。其次,实验研究了 O_3氧化脱硝性能,并分析了相关反应机理。结果表明,随O_3/NO摩尔比的增加,NO氧化率明显增加。当O_3/NO摩尔比≥1时,NO氧化率为100%。当O_3/NO摩尔比为1时,烟气停留时间对NO氧化率无明显影响。当烟气中有NO和SO_2同时存在时,SO_2对NO氧化率有一定的抑制作用,当O_3/NO摩尔比为1、SO_2浓度为1000 ppm时,NO氧化率只达到90%,而SO_2去除率为4%。最后,研究了湿法洗涤对O_3氧化脱硝性能的影响,分别开展了 NaC1O_2、NaClO、H2O_2协同O_3氧化脱硝实验,综合考虑选取NaClO较为合适。然后分别考察了 O_3浓度、NaClO溶液pH值、有效氯浓度对NO氧化率的影响。当NaClO溶液pH值为7时,增加O_3浓度和NaClO有效氯浓度,可以明显提高NO氧化率。由于NaClO溶液中有效氯成分比例随溶液pH值变化而变化,pH值对NaClO溶液湿法脱硝性能影响较大。当O_3浓度为300 ppm、NaClO有效氯浓度为10 mmol/L时,pH值3、7、11所对应的NO氧化率分别为100%、96%和67%。实验兼顾考虑溶液的酸碱腐蚀问题和脱硝率,建议采用pH值为7的NaClO溶液与O_3协同开展后续研究。
[Abstract]:At present, due to large amounts of sulfur oxides in exhaust gas containing vessel (SO_x), nitrogen oxide (NO_x), particulate matter (PM) and other pollutants, causing air pollution problems have become increasingly serious. The international maritime organization adopted MARPOL73/78 annex VI, NOx concentration in the exhaust gas set clear limits. In order to meet emission standards, people put forward the selective catalytic reduction (SCR), exhaust gas recirculation (EGR), washing wet oxidation, ozone (O_3) denitration method of ship exhaust oxidation different. Oxidation method in which O_3 has high denitration efficiency, simple in principle, it has a good application prospect. This paper makes a preliminary study the O_3 self decomposition characteristics, and then carry out O_3 oxidation denitration experiments, finally studied the wet scrubbing of O_3 oxidation affect denitrification performance and its mechanism. Firstly, the experimental study on the self decomposition of O_3 were investigated. Show that the gas temperature is the main factor affecting the self decomposition of O_3, with the increase of the flue gas temperature, O_3 decomposition rate increased. When the temperature is less than 100 DEG C, O_3 decomposition rate increased slowly, and when the temperature is greater than 200 DEG C, O_3 decomposition rate increased significantly. When the flue gas temperature is 100 degrees centigrade with gas residence time increases, O_3 decomposition rate increased slowly, the change trend of different concentration of O_3 corresponding to the O_3 since the decomposition rate is basically the same. Secondly, experimental study on the oxidation of O_3 DeNOx performance, the reaction mechanism and analysis. The results show that with the increase of O_3/NO molar ratio, NO oxidation rate increased significantly. When the molar ratio of O_3/NO aged 1, NO oxidation rate is 100%. when the O_3/NO molar ratio is 1, the residence time of flue gas on NO oxidation rate was not affected. When there are NO and SO_2 in the flue gas existing at the same time, SO_2 has inhibitory effects on NO oxidation rate when O_3/NO mole ratio was 1, SO_2 The concentration of 1000 ppm, NO oxidation rate only reached 90%, and the removal rate of SO_2 is 4%. finally, studied the effect of wet scrubbing on denitrification performance of O_3 oxidation, respectively by NaC1O_2, NaClO, H2O_2, O_3 CO oxidation denitration experiments, considering the selection of NaClO is chosen. Then the effects of the concentration of O_3, NaClO the pH value of the solution, effects of effective chlorine concentration on the oxidation rate of NO. When the NaClO and the pH value is 7, the increase of O_3 concentration and NaClO concentration of effective chlorine, can significantly improve the NO oxidation rate. Changes due to the effective chlorine NaClO solution composition with solution pH value change, pH value of NaClO solution wet denitration performance greater impact. When the O_3 concentration is 300 ppm, NaClO effective chlorine concentration was 10 mmol/L, NO oxidation pH value 3,7,11 corresponding rates were 100%, 96% and 67%. experiment considering acid-base corrosion problem solution and the rate of denitrification, recommends the use of the pH value of 7 NaClO solution and O_3 Carry out follow-up research in collaboration.

【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U664.9;X736.3

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