火电厂脱硝系统分区测量与优化控制应用分析

Application Analysis of Zoning Measurement and Optimization Control of Denitrification System in Thermal Power Plants

漳山电厂SCR (Selective Catalytic Reduction,选择性催化还原)反应器烟道弯头较多、布置曲折、烟道狭长等,致使烟气流场复杂且气流分布不均,NO_(x)单一测点无法准确地反映烟道内NO_(x)的分布,且不能在工况改变的情况下及时对喷氨量进行按需分配,造成局部欠喷或过喷现象,导致一部分NO_(x)没有充分反应,一部分氨气发生逃逸,脱硝效率降低。通过脱硝系统分区测量与优化控制改造,在SCR反应器的入、出口安装烟气NO_(x)网格法测量系统,对NO_(x)进行分区多点测量,准确反映SCR反应器烟道内污染物的分布状况。同时各分区调门按需喷氨,保证了喷氨格栅(AIG)氨氮摩尔比的相对高度均匀,有效降低了NO_(x)的排放量,减少了氨逃逸,降低了液氨成本,确保了SCR下游冷端设备的安全运行,达到了很好的控制效果。

The SCR(Selective Catalytic Reduction)reactor flue of Zhangshan Power Plant has many bends,winding arrangements,and narrow ducts,resulting in a complex flue gas flow field and uneven airflow distribution.A single NO_(x) measurement point cannot accurately reflect the distribution of NO_(x) in the flue gas,and the ammonia injection amount cannot be allocated as needed in a timely manner under changing working conditions,causing local under injection or over injection phenomena,resulting in insufficient reaction of some NO_(x) and escape of some ammonia gas,reducing denitrification efficiency.Through the partition measurement and optimization control transformation of the denitrification system,a flue gas NO_(x) grid measurement system was installed at the inlet and outlet of the SCR reactor to accurately reflect the distribution of pollutants in the SCR reactor flue gas by partitioning and multi-point measurement of NO_(x).At the same time,each partition adjusted the valve to spray ammonia as needed,ensuring a relatively uniform height of ammonia nitrogen molar ratio in AIG,effectively reducing NO_(x) emissions,minimizing ammonia escape,reducing liquid ammonia costs,and ensuring the safe operation of downstream SCR cold end equipment,achieving good control effects.