【作者】 董若凌；

【导师】 岑可法； 周俊虎；

【作者基本信息】 浙江大学 ， 工程热物理， 2006， 博士

【摘要】 再燃降低NOx排放技术是一种有效的氮氧化物控制手段，其作用效果与再燃燃料的选取直接相关，水煤浆的再燃应用拓宽了再燃燃料的选择范围，不论在经济性或高效性上均更具优势，本文即围绕这一燃料及其特点展开全面研究，内容涵盖与水煤浆脱硝能力提高相关的燃料特性分析、再燃动力学分析和再燃应用分析，等，籍此获得对水煤浆和再燃技术本身的进一步了解。 煤粉制浆后N物质挥发效应的增强和煤焦反应比表面积的改善是促进水煤浆高效脱硝的主要原因。热解试验揭示，水煤浆焦炭N（Char-N）、NH₃-N比例较煤粉含量低，焦油N（Tar-N）、HCN-N和N₂，etc等诸物质的比例则较之略高，温度、燃料特性、煤浆浓度和受热时间对N物质分配均有影响。BET和DR表面测试证实了煤浆焦比表面积的增大效果和微孔结构增多现象。 热天平用于煤（水煤浆）焦异相再燃作用研究后，所获得的样品随温度失重特性方便了再燃作用历程分析和规律把握，试验揭示：煤焦／NO作用具有分段进行的特性，制浆可以促进煤焦的异相还原优势，煤灰组份是造成反应分段的主要因素。试验动力学数据表明煤焦异相还原NO在低温阶段具有较低的活化能，而在高温阶段有较高的活化能。 水、煤粉和水煤浆的再燃区反应特性研究证明水份不单独具有明显的脱硝效果，水煤浆由于兼具煤粉和水份的作用优势而在再燃过程中表现出较高的脱硝能力。受挥发份析出峰值条件影响，水煤浆再燃效果在过量空气系数0.9时出现强势，适当提高再燃区温度、减少水煤浆浓度和降低燃料粒径颗粒有利促进脱硝效果，不同金属添加剂的脱硝催化效应相异。 0.25MW热态炉应用试验就水煤浆再燃效果进行了系统研究，证实水煤浆再燃技术可以有效降低锅炉排烟NOx浓度，水煤浆再燃应用效果与主燃区过量空气系数、再燃区过量空气系数、再燃燃料百分比、再燃燃料投入位置、再燃燃料输送动量、锅炉负荷等有关，目前应用水煤浆再燃技术后可获得的锅炉最高脱硝率约81％。 数值模拟是减少人工、缩短研究周期、方便预测和检验再燃效果的有效方法，本文所建立的水煤浆再燃模型较准确地反映了实际炉内状况，并提供有效预测、指导功能。 2.11MW燃煤四角炉煤粉再燃试验验证了再燃技术的普遍适用性，并就再燃对炉内燃烧状况的影响作全面分析：再燃技术的应用将一定程度改变炉内温度场，主要烟气成份如NOx、CO、SO₂的排放有不同程度更多还原

【Abstract】 NO_x reduction through reburning was an effective pollution control technology. Its efficiency is relative to the characteristics of reburing fuels. In order to explore the probality of NO_x reduction through coal water slurry （CWS） so as to expand its applied ranges, the information about fuel-N distribution during pyrolysis, reburning knetics and its utility ranges and reburning technology features were generally studied here.Nitrogen volatilization and surface areas increase are reasonable explanations for CWS’ high NO_x reduction efficiency. In the pyrolysis experiment, CWS’ char-N and NH3-N fraction are lower than the coals, while Tar-N, HCN-N, and N₂, etc fractions are greater. Temperature, fuels, CWS concentration and residence time are factors influencing N volatility. BET or DR surface analysis technology confirms the effect of increase of both specific area and microcelluiar structure after CWS making.When thermogravimetry was used to study the heterogeneous reaction of NO reduction, the weigh loss of samples with temperature recorded the Char reaction process detailedly. Through tests, it is found that the reaction between NO and Char has sectioned characteristics, this maybe relative to the mineral substance in the char. Slurrying can make coal char more reactive. The kinetic data show that activation energy of reaction at low temperature often is lower than that at high temperature.Water can not play a role in NO_x reduction alone. Owning the NO_x control advantages of both coal and water, CWS showed stronger NO_x reduction ability. Relative to the condition of volatiles peak value appearance, the NO_x reduction efficiency of CWS became better at the reburning zone excess air ratio of 0.9. With the increase of reburning zone temperature and decrease of fuel particle size, the CWS NO_x reduction efficiency increased. Lower CWS concentration favored reburning zone NO_x control. Different metal additives have different NO_x reduction catalytic effects.0.25 MW down fired furnace was used to study the characteristics of CWS reburning effects, temperature field change and carbon content in the fly ash. Variables examined during these tests were main combustion zone excess air ratio, reburning zone excess air ratio, percent heat input from reburning fuel, location of reburning zone, momentum of reburning fuel and furnace load. The best NO_x reduction efficiency of CWS reburning in this paper is 81%.A numerical method can save both time and manual power, even, convinene the reburning effect test. CWS reburning model built in this paper could simulated the更多还原