【作者】 金晶；

【导师】 李瑞阳； 张忠孝；

【作者基本信息】 上海理工大学 ， 热能工程， 2005， 博士

【摘要】 随着全球化石燃料使用量的持续增长，NO_x的排放控制问题已引起世界各国的普遍关注。长期以来，我国的能源结构一直以煤炭为主，因而燃煤是造成我国NOx排放污染的主要原因。在现有的脱氮技术中，燃料分级燃烧是最经济、有效的方法之一。对于众多的燃煤锅炉，采用煤粉分级燃烧不仅具有明显的NO_x还原效果，而且由于再燃燃料种类可与一次燃料相同，无需考虑双重燃料燃烧和输送的问题，因此更加容易实施，运行费用明显降低。 本课题针对超细煤粉分级燃烧NO_x还原过程中的具体问题，借助于热态试验、数值模拟和理论分析的方法展开研究，深入揭示了NO_x的还原机理，获得再燃条件下超细煤粉的燃烧特性以及不同燃烧工况下超细煤粉分级燃烧NO_x还原效果的基础数据，力求在保证良好的燃烧效率的前提下，最大限度地提高NO_x的还原效果。 文中首先根据NO_x的生成与破坏机理探讨了超细煤粉分级燃烧NO_x的均相与异相还原机理，利用敏感性分析建立了简化的超细煤粉分级燃烧NO_x还原化学动力学反应模型，发现了超细煤粉分级燃烧过程中NO_x还原的主要反应机理。 分别利用热重分析仪研究了煤粉在还原性气氛下热解时，挥发分的析出特性；创新性地借助于气相色谱仪与管式加热炉，研究了再燃条件下煤粉热解时碳氢组份的析出特性，首次获得了再燃区中热解温度、燃料特性、煤粉粒度对煤粉热解特性的影响规律，发现了以超细煤粉作为再燃燃料时NO_x还原效果提高的根本原因。 首次在热态煤粉炉的快速热解条件下，研究了再燃条件下超细煤粉的着火特性及燃料的燃尽特性，并通过理论计算进一步分析了煤粉着火及燃尽时间与煤粉粒度、煤种、氧浓度等因素的关系，为合理地分配主燃区、再燃区、燃尽区内的停留时间提供了重要的设计依据。 针对热态煤粉炉内超细煤粉分级燃烧NO_x的还原过程，建立了相应的物理模型及边界条件，并运用多相流动、传热、湍流燃烧、NO_x生成和还原等数学模型以及相应的数值计算方法，对炉内的热态速度场、温度场、主要燃烧产物及燃烧污染物NO_x的浓度场进行了数值模拟，研究了超细煤粉分级燃烧中，运行工况对NO_x还原效果的影响，计算结果对试验研究起到了很好的定性指导作用。 采用热态试验方法，研究了煤粉燃烧NO_x的释放特性以及超细煤粉分级燃烧过程中燃烧工况对NO_x还原效果的影响规律。通过试验研究与模拟计算结果的比更多还原

【Abstract】 With the global continued increase of fossil fuel consumption, the problem of NO_x emission control has caused widespread concern of the world. As most energy needed in China has been coal for a long period, and the energy structure will last in the future, coal burning is the main cause of NO_x emissions, which pollutes the environment heavily in our country. To control NO_x emission, one of the most valid methods is reburning technology, which reduces the NO_x formed in primary burning zone by the deoxidized atmosphere in reburning zone. The technology is a promising method for its lower cost, easier realization and higher NO_x reduction efficiency, due to the reburning fuel being able the same as the primary one.Though investigating the specific problems about NO_x reduction in superfine pulverized coal reburning process by means of thermal tests, simulations and theoretical analyses, the thesis is to reveal the mechanism of NO_x reduction, get the basic data of burning characteristics of superfine pulverized coal in reburning process and the effects of NO_x reduction for superfine pulverized coal reburning under various burning conditions, and farthest improve the reduction efficiency of NO_x with good combustion efficiency.Firstly, based on the formation and reduction mechanism of NO_x, the reduction mechanism of homogenous phrase and heterogeneous phrase is discussed. A simplified chemical dynamic reaction model of NO_x reduction process of superfine pulverized coal reburning is established by means of sensitive analysis, and the main reaction mechanism is found for the process.By using thermogravimetry, the volatile releasing behavior is investigated separately when pulverized coal pyrolyzed in the deoxidized atmosphere. The releasing behavior of CmHn component of pulverized coal pyrolyzed under reburning condition is investigated innovatively by means of gas chromatography and tube heater. The effects of pyrogenation temperature, fuel characteristics and coal particulate size on pyrogenation behavior of pulverized coal in reburning zone are obtained for the first time. The fundamental reasons are found for increase reduction efficiency of NO_x when superfine pulverized coal used as reburning fuel.The ignition and burnout characteristics of superfine pulverized coal reburning are experimentally studied firstly under the condition of rapid pyrogenation in a thermal pulverized coal furnace. And in order to provide design basis for reasonably distributing更多还原