基于自发辐射分析的燃煤锅炉内温度及气相钠同时在线监测

Simultaneously on-line measurement of temperature and gaseous sodium in coal-fired furnace based on spontaneous emission analysis

准东煤燃烧过程中释放的碱金属极易导致炉膛受热面沾污、结渣等问题,影响锅炉运行的安全性,开展燃烧过程中碱金属定量测量对优化燃烧有重要意义。基于自发辐射光谱分析(Flame emission spectrometry,FES)技术开展燃煤锅炉内温度和气相钠浓度同时在线监测研究,首先提出了采用火焰光度计检验FES技术测量燃烧火焰中气相钠浓度的试验方法,并开展了气相Na浓度测量的验证试验,在0~12.2 mg/m^(3)测量值与实际值具有较高精度,最后研制了一套燃烧温度/气相钠浓度在线监测系统并应用于大型火电机组煤粉锅炉现场。连续在线监测结果表明:气相Na浓度、火焰温度与机组参数具有正相关性且同步变化,测点区域最高温度和气相Na质量浓度分别为1220℃和2.3 mg/m^(3)。基于在线监测结果能为后续炉内受热面沾污、结渣预报和锅炉燃烧调整提供指导。

The alkali metals released in the combustion process of high alkali fuels such as Zhundong coal and biomass are probable to cause fouling and slagging on heating surface of furnace and affect the operation safety.Therefore,quantitative measurement of alkali metals in combustion process is of great significance for combustion optimization.The simultaneous on-line measurement of temperature and gas phase sodium concentration in coal-fired boilers was carried out based on spontaneous emission spectrum analysis technology.First,an experimental method for measuring gas phase sodium concentration in combustion flame by using flame photometer to test FES(Flame emission spectrometry)technology was proposed,and the verification experiment of measuring gas phase Na concentration was carried out.The measured value and the actual value in the range of 0-12.2 mg/m^(3)have high accuracy.Finally,an on-line measurement system for combustion temperature and gas phase sodium concentration was developed and applied to the site of large-scale thermal power plant pulverized coal boiler.The continuous online monitoring results show that the gas Na concentration and flame temperature have a positive correlation with the unit parameters and change synchronously.The maximum temperature and gas Na concentration in the measuring point area are 1220℃and 2.3 mg/m^(3),respectively.Based on the on-line measurement results,it has guiding significance for the subsequent prediction of fouling and slagging on the heating surface of the furnace and the adjustment of boiler combustion.