600MW火电机组脱硝控制系统分析及优化

发布时间：2018-08-18 12:01

【摘要】：近年来,随着我国火力发电装机总量的不断增加,火电厂氮氧化物的排放量也日益增长,特别是燃煤过程中产生的NOx是造成了酸雨、“光化学烟雾”等二次污染的重要物质。因此,控制燃煤电厂的NOx排放已经是一个迫在眉睫的问题。选择性催化还原(SCR)烟气脱硝技术由于具有脱硝效率高、运行稳定可靠等优点,已成为国内外应用最为广泛的烟气脱硝技术之一。本文以某发电厂600MW机组脱硝系统为研究对象,对火力发电厂烟气脱硝控制策略进行优化。基于SCR烟气脱硝的工艺及工作原理,并结合电厂的实际情况,分析了NOx生成机理。在分析原控制方案不足的基础上,采用主元分析法确定了建模的主导变量,基于工程实际,采用多元一次拟合建立了燃烧侧扰动对SCR入口侧NOx浓度影响的数学模型,采用SCR入口侧NOx浓度的动态预估值代替实际测量值的方法,解决了烟气中NOx浓度测量信号滞后的问题。为了在不同工况下脱硝控制系统均能具有满意的控制品质,通过现场试验建立了脱硝系统在不同机组负荷下的动态数学模型,基于试验结果,对脱硝系统的控制参数进行了自适应调整。优化后的SCR脱硝系统已经投入运行一年左右,系统运行良好,取得了可观的经济意义和社会意义,经过优化前后控制效果对比,验证了优化后的SCR脱硝控制系统具有良好的控制品质。
[Abstract]:In recent years, with the continuous increase of the total installed capacity of thermal power plants in China, the emission of nitrogen oxides from thermal power plants is also increasing day by day. Especially, the NOx produced in the coal combustion process is an important substance that causes acid rain, photochemical smog and other secondary pollution. Therefore, it is an urgent problem to control the NOx emission from coal-fired power plants. Selective catalytic reduction of (SCR) flue gas denitrification technology has become one of the most widely used flue gas denitrification technologies at home and abroad due to its high denitrification efficiency and stable operation. In this paper, the control strategy of flue gas denitrification in thermal power plant is optimized by taking the denitrification system of 600MW unit in a power plant as the research object. Based on the technology and working principle of SCR flue gas denitrification, and combined with the actual situation of power plant, the formation mechanism of NOx is analyzed. Based on the analysis of the deficiency of the original control scheme, the principal component analysis method is used to determine the main variable of the model. Based on the engineering practice, the mathematical model of the influence of combustion side disturbance on the NOx concentration at the inlet side of SCR is established by using the multivariate one-step fitting. The dynamic prevaluation of NOx concentration at the inlet side of SCR is used to replace the actual measurement value, which solves the problem of the lag of the measurement signal of NOx concentration in flue gas. In order to have satisfactory control quality of denitrification control system under different working conditions, the dynamic mathematical model of denitrification system under different unit loads was established through field test. The control parameters of denitrification system are adjusted adaptively. The optimized SCR denitrification system has been put into operation for about one year. The system has been running well and has achieved considerable economic and social significance. The optimized SCR denitrification control system has good control quality.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621

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