燃气机组NO_x监测系统现状及其改进措施

随着燃气机组NO_x浓度排放要求日趋严格,其监测系统运行工况发生变化,原有监测仪表已不适用。通过分析NO_x监测技术及其适应性和烟气预处理技术及其适应性,对燃气机组NOx监测系统现状有了明确的认识。结合HJ 75—2017和HJ 76—2017标准,针对现有监测系统中存在量程大、低浓度测量精度差、未监测NO_2等问题,提出了一系列改进措施,如优先采用化学发光法NO_x测量技术,增加NO_2监测装置,采用低量程高精度CEMS仪表及性能优越的预处理装置,落实防雷设施等,同时着重考虑配置氨逃逸、氧量和湿度等分析仪表,以满足控制和监测要求。研究结果也同样适用于普通火电机组。

Current Situation and Improvement Measures of NOx Monitoring System for Gas Turbine Unit

With the increasingly strict requirements for the concentration of NO_x emission from gas-fired units, the operating condition of the monitoring system has changed such that the original monitoring instruments becomes no longer applicable. By analyzing the NO_x monitoring technology and the flue gas pretreatment technology as well as their adaptabilities, a clear understanding of the current situation of the NO_x monitoring system for gas units is obtained. In compliance with HJ 75-2017 and HJ 76-2017 standard, regarding the issues in existing monitoring system such as large measurement range, poor measurement accuracy for low concentration and lack of NO₂ monitoring functionality a series of improvement measures are put forward, e.g., giving priority to chemiluminescence method in NO_x measuring technology, adding NO₂ monitoring devices, using low range and high precision CEMS instrument and pretreatment device with superior performance, implementation of the lightning protection facilities, etc.. Meanwhile the installation of ammonia escape, oxygen and moisture analysis instrument is taken into account in order to meet the control and monitoring requirements. The results are also applicable to regular thermal power units.