【作者】 王剑；

【导师】 吴少华； 高建民；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2014， 硕士

【摘要】 长久以来，我国是世界上煤炭消费量最大，同时也是锅炉生产和使用最多的国家，因此排放了大量的氮氧化物，引发日益严重的环境问题。这其中燃煤工业锅炉排放占了很大比重，由于锅炉改造困难、运行管理水平低和环保法规限制少等原因，工业锅炉的氮氧化物排放问题迟迟未能妥善解决。利用烟气携带煤焦技术能在不大幅度改造锅炉的前提下，实现降低氮氧化物排放同时提高燃烧效率的目的。由于前人有关煤焦-NO反应的研究大多是应用于煤粉锅炉再燃，其研究结果并不一定适用于工业锅炉。为此，本文以工业锅炉氮氧化物控制为背景，开展了大粒径煤焦异相还原NO的实验研究，为强化层燃条件下烟气携带煤焦还原NO技术提供理论上的支撑。本文选用朔州烟煤在水平管式炉惰性气氛条件下制备了9种不同热解条件的大粒径煤焦样品，对原煤及煤焦进行了工业分析，通过压汞仪测量煤焦的孔隙结构，研究了制焦停留时间和热解温度对孔径分布特征的影响，发现低温下停留时间增加有利于增大煤焦比表面积和孔容积，停留时间较短时高温有利于增加煤焦比表面积和孔容积。然后应用X射线衍射仪，分析了热解条件对煤焦微晶结构的影响，结果表明热解温度升高有利于微晶结构向有序化方向发展。并通过压汞仪和扫描电镜联合使用，分析了预氧化对煤焦表面形态的影响，得到预氧化能使煤焦的孔隙变得更发达的结论。在立式固定床反应器上利用程序升温法（250℃~1000℃温度区间），研究了惰性气氛下制焦条件对大粒径煤焦异相还原NO反应的影响规律，发现制焦温度和停留时间增加都不利于煤焦-NO反应的进行。通过在反应气氛中添加氧气，在恒温加热条件下研究了氧气对大粒径煤焦-NO反应的重要作用，结果表明反应初期高氧浓度比低氧或无氧条件更能促进反应的进行，在较高氧浓度条件下改变实验温度对大粒径煤焦-NO反应的影响不大。经预氧化处理后，煤焦还原NO的能力有所提升；一定氧浓度下预氧化时间越长煤焦反应性越好，超过最佳预氧化浓度后，煤焦的反应性有所下降。本文还采用浸渍法使煤焦担载不同金属元素，通过与未担载金属的煤焦对比，得到金属元素的催化活性排序为Fe>Cu>K>Na>Ca>Mg。更多还原

【Abstract】 For a long time, China is the world’s largest consumer of coal and boilers.Therefore, there is a large number of emissions of nitrogen oxides causingincreasingly serious environmental problems. Emissions from coal-fired industrialboilers account for a large proportion. However, due to the reasons of difficultboiler renovation, low operation and management level and lack of restrictiveenvironmental regulations, the problems of NOxemission on industrial boilers arenot properly addressed. The technology of flue gas carrying coal char can achievethe purpose of improving combustion efficiency and reduce nitrogen oxideemissions without substantial transformation on boilers. Since most studies on char-NO reaction is used in pulverized coal boilers’ reburn predecessors, its findings arenot necessarily applicable to industrial boilers. Based on the experimental study onlarge size char-phase reduction of NO, the paper provides support to strengthen thetechnical on data, which is important to reduce nitrogen oxide emissions ofindustrial boilers.The paper chooses Shuozhou bituminous coal for the preparation of differentlarge particle char samples in9kinds of pyrolysis conditions under inert atmosphereof horizontal tube furnace and research char properties by industry analysis.Through measuring the pore structure of coal char by mercury instrument, the paperexplore the influence of residence time and pyrolysis temperature on pore sizedistribution. The results show that increasing the residence time at low temperaturesis conducive to increasing the specific surface area and pore volume of char, shortresidence time char at high temperatures help to increase the surface area and porevolume. Then the application of X-ray diffraction analysis is done to discover theeffects of pyrolysis conditions on char microcrystalline structure. The results showthe pyrolysis temperature is conducive for microcrystalline structure to orderlydirection. And using mercury analyzer and scanning electron microscopy incombination to explore the influence of pre-oxidation of the surface morphology ofchar. It is found that char becomes more developed conclusions by getting pre-oxidation of the pore.The paper studies the influence of pyrolysis conditions to heterogeneousreduction reaction of large size char and NO using temperature-programmed method(250~1000℃) on a vertical fixed bed reactor. By adding oxygen to the reactionatmosphere, the paper studies the effect of concentration of oxygenlarge to char-NOreaction at constant temperature. the initial reaction results show that a high oxygenconcentration is better to promote the reaction than hypoxic or anaerobic conditions,and changing the experimental temperature at higher oxygen concentrations has little effect on large size char-NO reaction. After pre-oxidation treatment, thecapability of char reducing NO is been improved. When the pre-oxidation time islonger, the reactivity is better at a certain oxygen concentration. More than the bestpre-oxidation concentration, reactivity of coal chars decreases. This paper alsomakes the coal loading different metal elements by impregnation method. The resultshow that the order of catalytic activity of metal elements is Fe>Cu>K>Na>Ca>Mgry comparising with the char not supported metal.更多还原