火电厂脱硝系统改造研究

发布时间：2018-12-13 18:48

【摘要】：近年来随着社会经济的快速发展，电力供应快速增加，燃煤量显著增加，火电厂氮氧化物的排放总量快速增加。氮氧化物的排放对于大气环境有着严重的危害性，必须有效地控制燃煤发电过程中氮氧化物的生成量，控制氮氧化物的排放已经成为当前我国环境保护工作的重点。为降低火电机组的NOx排放以满足日益严格的排放标准以及改善空气质量，新老火电机组的烟气脱硝工程显得格外重要。本文研究了火电机组NOx的生成机理以及影响因素，氮氧化物排放的控制及处理方法，并对不同的氮氧化物的处理方法进行了比较，重点研究了选择性催化还原法的原理、脱硝反应过程中所发生的副反应、脱硝系统的的组成、反应器布置方案、脱硝工艺选择的原则、脱硝反应剂的制备以及不同脱硝剂反应的比较，并分析了加装SCR装置对锅炉主机设备的影响以及反应器旁路烟道等有关问题。结合某厂机组实际情况采取先降后脱的路线对该厂#156机组进行了低氮燃烧器和脱硝工程的改造。根据改造前后机组运行状况以及有关电科院的试验结果，通过对低氮燃烧改造、分级配风降低主燃烧区域的温度场水平，有效减少了W型锅炉热力型NOx的生产量，明显地降低了锅炉烟气NOx含量水平。由燃烧器改造前330-335MW负荷下NOx排放浓度平均值为1210mg/m3（标态干基，O2=6%）降到改造后330MW负荷下NOx排放浓度602mg/m3，达到预期的改造目的（低于800mg/m3）。在350MW负荷下，锅炉实测热效率为92.63%，，高于设计值91.82%，在其它工况下，锅炉热效率均高于设计值，表明#6锅炉经济性能良好。改造后各工况下的锅炉热效率均高于改造前的锅炉热效率。改造工程通过采用先降后脱的技术路线，对现有燃烧器进行低氮改造使氮氧化物降低至一定水平后再进行烟气脱硝，最终使NOx的排放浓度达到《火电厂大气污染物排放标准》（GB13223-2011）允许的氮氧化物排放浓度200mg/m3，为同类机组的脱硝系统改造提供宝贵经验。
[Abstract]:In recent years, with the rapid development of social economy, the power supply is increasing rapidly, the amount of coal burning is increasing significantly, and the total amount of NOx emission from thermal power plants is increasing rapidly. The emission of nitrogen oxides is harmful to the atmospheric environment. It is necessary to effectively control the amount of nitrogen oxides produced in the process of coal-fired power generation and control the emission of nitrogen oxides has become the focus of environmental protection in China. In order to reduce the NOx emissions of thermal power units to meet the increasingly stringent emission standards and improve air quality, the flue gas denitrification project of new and old thermal power units is particularly important. In this paper, the formation mechanism and influencing factors of NOx, the control and treatment methods of NOx emission are studied, and the different treatment methods of NOx are compared, and the principle of selective catalytic reduction method is emphatically studied. The side reactions occurred in denitrification process, the composition of denitrification system, the layout of reactor, the principle of denitrification process selection, the preparation of denitrification reagents and the comparison of different denitrification reagents. The influence of SCR installation on boiler mainframe equipment and the related problems of reactor bypass flue were analyzed. The low nitrogen burner and denitrification project of # 156 unit were retrofitted according to the actual situation of the unit. According to the operating condition of the unit before and after the revamping and the test results of the electric institute concerned, by reforming the low nitrogen combustion, the temperature field level of the main combustion area is reduced by the staged air distribution, and the production of the thermal type NOx of the W type boiler is effectively reduced. The NOx content of boiler flue gas is obviously reduced. Before the revamping of the burner, the average concentration of NOx emission under 330-335MW load was reduced to 1210mg/m3 (standard dry base, O _ 2O _ 2 ~ (6%) to 60 ~ 2 mg / m ~ (3) of NOx emission concentration under 330MW load after revamping, which achieved the desired revamping purpose (lower than 800mg/m3). Under 350MW load, the measured thermal efficiency of boiler is 92.63, which is higher than the design value of 91.822.In other conditions, the thermal efficiency of boiler is higher than the design value, which indicates that the economic performance of # 6 boiler is good. The thermal efficiency of boiler is higher than that of boiler before revamping. By adopting the technical route of first reducing and then removing the existing burners, the revamping of the existing burners can reduce the nitrogen oxides to a certain level before flue gas denitrification. Finally, the emission concentration of NOx is up to 200 mg / m ~ 3 of nitrogen oxide emission permitted by GB13223-2011, which provides valuable experience for the revamping of denitrification system of similar units.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：X773;TM621

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