【作者】 张健强；

【导师】 邱朋华；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2010， 硕士

【摘要】 燃煤电站锅炉产生的氮氧化物(NOx)是大气的主要污染物之一。随着环保要求的逐渐提高,燃煤电站烟气脱硝迫在眉睫,急需成本低廉、高效的脱硝技术。将再燃与SNCR结合起来的先进再燃技术具有很好的技术、经济优势,有望成为我国控制燃煤电站NOx排放的主流技术。本文首先通过在两段反应式一维燃烧反应器上进行了煤粉再燃、SNCR和煤粉先进再燃脱硝试验,研究再燃区化学当量比(SR)、煤粉再燃比(RFP)、再燃区温度(T1)、NH3/NO摩尔比(NSR)以及停留时间(τ)对煤粉先进再燃脱硝的影响规律,并分析再燃区出口条件对反应体系下游的NOx还原反应的影响。试验结果表明:综合考虑,SR=0.8左右较适合整体先进再燃脱硝;SR=0～0.6范围内时,RFP=25%的先进再燃的脱硝效率最高,SR=0.8～1.2范围内时,RFP=15%的先进再燃的脱硝效率最高;再燃燃料与氮还原剂的投入量存在一个最优配比值,T1=1250℃,T2=900℃条件下,RFP=20%,NSR=1时,先进再燃的脱硝效率最高,RFP=10%,NSR=1.5时,先进再燃的脱硝效率最高;先进再燃的T1最佳值为1100℃;再燃段出口中NO、NH3、CH4、CO、HCN是影响先进再燃脱硝效率的主要气体成分,研究表明,CH4、CO、HCN三种气体均对先进再燃脱硝反应有促进作用,其中,CH4和HCN对先进再燃的影响最大,而CO的影响相对较小。然后本文整合已有的再燃和SNCR反应机理,应用Chemkin软件建立化学动力学模型,模拟煤粉先进再燃同相反应过程,将试验结果与模拟结果进行对比,验证整合机理的正确性与可用性。最后通过对煤粉先进再燃的生成率分析,研究了重要基元反应、重要反应物等对脱硝效率的影响,并通过归一化的生成率系数描述了脱硝反应的进行过程,绘制先进再燃反应脱硝路径,并与已有的再燃反应、SNCR反应脱硝路径进行比较。结果表明:先进再燃脱硝反应是以氨基为主导、再燃燃料起重要作用的还原反应,三种脱硝过程中起作用的物质、重要的中间产物、重要的活性基团等都发生了变化,但NH2是三种过程中共同的重要中间产物,OH是三种反应中共同的重要活性基团。更多还原

【Abstract】 Nitrogen oxide (NOx) from coal-fired boiler is one of the major pollutants in the atmosphere. With the gradual increase of environmental requirements, coal-fired power station flue gas denitration is imminent that low-cost and efficient denitration technology is in urgent need. Advanced reburning technology which is the combination of reburning and SNCR technology has important technical superiority and an economic advantage, and it is expected that China will adopt as a mainstream technology to control the NOx emissions from coal-fired power stations.First, by conducting experiments on pulverized coal reburning in a Two-staged Drop Tube Reactor, SNCR and advanced pulverized coal reburning NO reduction, a study was carried out on the effects of the stoichiometric ratio of reburn zone(SR), reburning fule proportion(RFP), reburning zone temperature(T1),NH3/NO molar ratio(NSR) and the residence time(τ) on advanced pulverized coal reburning. Afterwards, analysis was completed on the effects of reburning zone exit conditions of the reaction system on the downstream NOx reduction reaction.The results showed that: considering as a whole, it is more suitable for advanced reburning NO reduction total when SR=0.8 or so; when SR=0~0.6, the advanced reburning NO reduction efficiency of RFP=25% is the highest; when SR=0.8~1.2, advanced reburning NO reduction efficiency of RFP=15% is the highest. There is an optimal ratio value on reburning fuel and reductant inputs of nitrogen, under the circumstance that T1=1250℃, T2=900℃, when RFP=20%, NSR=1, the efficiency of advanced reburning NO reduction is the highest; when RFP=10%, NSR=1.5, the efficiency of advanced reburning NO reduction is the highest; the best value for T1of advanced reburning is 1100℃; NO, NH3, CH4, CO , HCN of reburning section exports are the main gas component which have effect on advanced reburning NO reduction efficiency. The research showed that, CH4, CO and HCN all help to promote NO reduction in advanced reburning process. Among the three kinds of gases, CH4 and HCN have the greatest impact on advanced reburning while the impact of CO is relatively insignificant.In this paper, the existing reburning and SNCR reaction mechanism are integrated and we employ the Chemkin software to build chemical kinetics model and to simulate the same phase reaction process of advanced pulverized coal reburning. The test results and simulation results were compared to verify the accuracy and availability of integrated mechanism. Finally, the impacts of important elementary reactions and important reactants on NO reduction are studied by rate of production analysis and the NO reduction processes are described by the normalized rate of production. NO reduction paths of advanced reburning reactions are given and compared with the existing NO reduction paths of reburning, SNCR reaction. The results showed that: advanced reburning NO reduction reaction is amidogen-oriented and reburning fuel plays an important role in the reduction reaction. In the three NO reduction reactions, the work substances, the important intermediate products and the important active groups all make some changes, while NH2 is a common important intermediate products, and the OH is an common important active groups in the three processes.更多还原