【作者】 薛方明；

【导师】 赵毅；

【作者基本信息】 华北电力大学 ， 能源环境工程， 2014， 博士

【摘要】 燃煤产生的二氧化硫、一氧化氮和元素态汞均会对生态环境和人体造成巨大危害。截止目前,针对二氧化硫、一氧化氮和元素态汞等单一污染物,国际国内专家已经先后研发出一系列相应的成熟控制技术,例如石灰石-石膏法脱硫,选择性催化还原(SCR)和选择性非催化还原(SNCR)脱硝以及活性炭脱汞。这种分级治理方式普遍存在占地面积大、设备投资和运行费用高,系统稳定性差等问题。因此,研发具有设备投资费用少、运行成本低和无二次污染的烟气同时脱硫脱硝脱汞新工艺成为了国内外燃煤烟气污染物控制研究的热点。本课题在“863”课题,燃煤烟气循环流化床脱硫脱汞一体化及多污染物协同净化技术研究与示范资助下,在详细调研前人研究的基础上,对可实现二氧化硫、一氧化氮和元素态汞同时氧化和脱除的吸收溶液进行了大量筛选,并合成了二过碘酸合铜(diperiodatocuprate(Ⅲ), DPC)和二过碘酸合镍(diperiodatonicke late(Ⅳ), DPN)。通过实验确定了二者在喷射鼓泡反应体系中的最佳实验条件,在最佳条件下,利用DPC溶液可实现同时脱除90%的Hg0,98%的SO2和56.8%的NO；利用DPN溶液可实现同时脱除86.2%的Hg0,98%的SO2和56.2%的NO。为了降低吸收剂成本和二次环境污染,在预氧化体系实验平台上,以H2O2+添加剂N+添加剂F (HNF)为吸收溶液,开展了同时氧化脱除S02、NO和Hg0的最佳实验,在最佳条件下,SO2, NO和Hg0的脱除效率分别达到99%,81.5%和91.2%。通过上述实验研究,提出了三种同时脱硫脱硝和脱汞的新方法。通过对反应过程的热力学计算和反应产物的离子色谱(IC)、冷原子荧光和X-射线衍射(XRD)检测,揭示了脱除反应机理,其中DPC体系实验产物检测结果显示SO2的脱除产物为SO42-、NO的脱除产物为NO3-, Hg0被氧化为Hg2+。根据前人研究结果和最佳反应条件下溶液的pH值对DPC存在形态进行了研究,确定DPC溶液主要的氧化形态为[Cu(OH)2(H3IO6)2]3和[Cu(OH)2(H3IO6)]-。DPN体系实验产物的检测结果与DPC相同,且采用相似方法确定DPN溶液主要的氧化形态为[Ni(OH)2(H3IO6)2]2-和[Ni(OH)2(H3IO6)(H2IO6)]3-。预氧化体系实验产物检测结果显示在管道中NO被氧化为NO2；管壁内残渣中检测到亚硫酸盐、硫酸盐、亚硝酸盐和硝酸盐；后续吸收溶液中SO2的脱除产物为SO42-,而NO的脱除产物为NO3-, Hg0被氧化为Hg2+。热力学分析结果证实了反应发生的可能性和反应程度,同时显示在气相产物中可能存在少量的SO3、NO3、N2O5和N203。基于上述体系的同时脱硫脱硝脱汞宏观反应动力学实验研究,计算出DPC体系同时脱硫脱硝脱汞反应中SO2、NO和Hg0的分级数分别为1.32、2.08和1.58,反应的平均表观活化能分别为9.89kJ/mol、17.05kJ/mol和28.02kJ/mol。DPN体系同时脱硫脱硝脱汞反应中SO2、NO和Hg0的分级数分别为1.36、2.12和1.63,反应的平均表观活化能分别为12.54kJ/mol、21.27kJ/mol和33.03kJ/mol。预氧化体系同时脱硫脱硝脱汞反应中SO2、NO和Hg0的分级数分别为1.03、1.10和0.83,反应的平均表观活化能分别为6.84J/mol、19.15kJ/mol和11.85kJ/mol。更多还原

【Abstract】 Sulfur dioxide, nitric oxide and elemental mercury produced by burning coal have harm to ecological environment and human body. Up to now, in order to removal sulfur dioxide, nitric oxide and elemental mercury and other pollutants in a single, international and domestic experts have successively developed a series of corresponding maturity control technology, such as limestone-gypsum desulfurization, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) denitrification and activated carbon mercury removal. This is common hierarchical governance covers an area of big, the equipment investment and operation cost is high, the poor stability of the system. Research and development has the advantages of low equipment investment cost, low operation cost and no secondary pollution of new technology of flue gas desulfurization denitration at the same time to take off the mercury has become the hot topics in the study of coal-fired flue gas pollution control at home and abroad.This topic is "863" project, the integration of coal-fired flue gas circulating fluidized bed desulfurization to take off the mercury and more pollutants purification technology research and demonstration to fund together. On the detailed investigation and research, we have screened absorbent of desulfurization, denitration and Hg0removal at the same time, and synthesized diperiodatocuprate(Ⅲ)(DPC) and diperiodatonickelate(Ⅳ)(DPN). The best experimental conditions were determined by the experiment in the bubbling reaction system. Under the optimal condition,90%of Hg0,98%of SO2and56.8%of NO were removed by the DPC at the same time. Using DPN solution could remove86.2%of Hg0,98%of SO2and56.2%of NO. In order to reduce the sorbent cost and secondary pollution of the environment, experiments using absorbent of H2O2, additive N and F (HNF) on simultaneous removal of SO2, NO and Hg0were carried out in the preoxidation experiment platform. Under the best condition, SO2, NO and Hg0removal efficiency reached99%,81.5%and91.2%. Through the experimental research, this paper put forward three kinds of methods to simultaneous desulfurization, denitration and mercury removal.Detection result produced by the thermodynamic calculation of reaction process and reaction product ion chromatography (IC), cold atomic fluorescence and X-ray diffraction (XRD) revealed the removal mechanism. According to detection result, reaction products of SO2, NO and Hg0were SO42-, NO3-and Hg2+. According to the results of previous studies and the optimum reaction conditions the pH of DPC, the main oxidized form of DPC were [Cu(OH)2(H3IO6)2]3-and [Cu(OH)2(H3IO6)]-.The reaction products of DPN system were as same as the DPC reaction products, the main oxidized form of DPN were [Ni(OH)2(H3IO6)2]2-and [Ni(OH)2(H3IO6)(H2IO6)]3-. In the preoxidation experiment platform, NO was oxidized to NO2, sulfite, sulfate, nitrite and nitrate were detected in the pipeline. In the subsequent bubbling device, reaction products of SO2, NO and Hg0were SO42-, NO3-and Hg2+. Thermodynamic analysis results proved the possibility of a reaction and reaction degree, at the same time shows there may be a small amount of SO3^NO3、N2O5and N2O3in the product gas phase.Based on the above system of simultaneous removal of SO2, NO and Hg0macro reaction kinetics experiment research, the reaction order of simultaneous removal of SO2, NO and Hg0with respect to SO2, NO and Hg0were1.32,2.08and1.58, respectively, in DPC system. Apparent active energy of simultaneous removal of SO2, NO and Hg0were9.89kJ/mol,17.05kJ/mol and28.02kJ/mol, respectively, in DPC system. In DPN system, the reaction order of simultaneous removal of SO2, NO and Hg0with respect to SO2, NO and Hg0were1.36,2.12and1.63. Apparent active energy of simultaneous removal of SO2, NO and Hg0in DPN system were12.54kJ/mol,21.27kJ/mol and33.03kJ/mol. In preoxidation experiment platform, the reaction order of simultaneous removal of SO2, NO and Hg0with respect to SO2, NO and Hg0were1.03,1.10and0.83. Apparent active energy of simultaneous removal of SO2, NO and Hg0in preoxidation experiment platform were6.84kJ/mol,19.15kJ/mol and11.85kJ/mol.更多还原