【作者】 范志林；

【导师】 张军；

【作者基本信息】 东南大学 ， 热能工程， 2005， 硕士

【摘要】 NO_x作为最重要的大气污染物之一,以其危害大、治理难引起世界各国的高度重视。再燃烧技术以其经济有效性而成为控制NO_x排放的最有前途的方法之一。用生物质作为再燃燃料还原NO_x具有与天然气还原效果相当的高效性,利用生物质、用生物质气替代化石燃料作为再燃燃料,一方面生物质气作为新型可再生性能源提供能源,在一定程度上可以缓解能源紧张的局势,另一方面生物质气作为再燃燃料对燃煤NO_x的还原效果相当理想,此外燃用生物质气时燃料型NO_x、SO_x大为减低、CO₂零排放等特点使得生物质在环境保护方面更具积极意义。显然,生物质气再燃还原燃煤NO_x的研究是一项十分有前景的研究。本文首先阐述了课题的研究背景及现状,指出生物质气再燃还原燃NO_x将能源与环境问题结合到一起的重大研究意义。然后通过对生物质基本性质分析、生物质热解特性研究、生物质气体成分分析等逐步深入地研究,掌握了生物质气的生成、组成成分及其影响因素。在对生物质气充分把握的基础上对生物质气再燃还原燃煤NO_x进行了大量的实验研究和理论分析。实验在自行设计搭建的小型实验台上进行,以模拟烟气和模拟生物质气作为实验气源,通过测量反应器前后NO的浓度变化来确定生物质气对NO的还原效果。研究表明,在800-1200℃温度范围内,NO脱除率随再燃温度和停留时间的增大而增大,随烟气中初始NO浓度、SO₂浓度和水分的增加而减小,随着平衡比的增加脱除率呈先升后降的趋势,在平衡比为1.15左右脱除率达最大。最后在获得实验数据的基础上建立模型、利用CHEMKIN软件对该过程进行了数值模拟研究。模拟结果与实验结果基本相符,并且所选用5元素、145组分、1006基元反应的机理很好地解释了实验现象,这表明所建模型和所选机理是切实可行的。更多还原

【Abstract】 As one of the most important air pollutants, NO_x has drawn wide attention of the world because of its high hazard and hard treatment. Reburning technology is one of the most promising methods to reduce NO_x emission for its economy and efficiency. As reburning fuels, biomass and natural gas are almost matched in NO_x reduction. Using biomass and reburning with biomass gas instead of fossil fuels can not only remove NO_x efficiently but also ease the energy crisis in a certain extent for its renewability. Further more, for the lower N and S contents in biomass, reburning with biomass gas can greatly decrease the emission of NO_x and SO_x from fuel, and the net emission of CO2 is zero. At the point of this, as a kind of reburning fuel, biomass is of great positive environmental significance. Obviously, this is a quite promising research.In the first chapter, the background and research state were discussed. The important significance of combining the energy crisis and environment pollution was indicated. Then basic property of biomass, pyrolysis character and the composition of biomass gas were studied respectively. In this way, the production process and the components of biomass gas and the influence factors were mastered. Based on the master of biomass gas, a serial of experimental and theoretical researches of NO_x reduction with biomass gas as reburning fuel were carried out. All experiments were carried out on the small-scale test facility self-designed and manufactured. All gases used in experiments were simulated gases. The NO_x reduction efficiency was calculated by measuring the concentration of NO in the inlet and outlet of reactor. The results suggested that in the range of 800-1200℃, the NO_x reduction efficiency increased with the increasing of reburning temperature and residence time. But with the increasing of initial NO concentration, SO₂ concentration and moisture, NO_x reduction decreased. And NO_x reduction efficiency increased firstly and the decreased while the equivalence ratio increasing, and at the point of 1.15 the NO_x reduction efficiency reached the maximum. Lastly, a model was developed on the base of experiments and numerical simulation for the reburning process was carried out utilizing the software CHEMKIN. The results showed that the model could well predict the reburning process.更多还原