基于炉膛水冷壁H_(2)S气氛场实时测量的锅炉运行监测与优化研究

Research on boiler operation monitoring and optimization based on real-time measurement of furnace water-cooled wall H_(2)S atmosphere field

为揭示锅炉水冷壁H_(2)S在不同负荷时的浓度分布、H_(2)S与炉膛组分CO和SO_(2)的关系、结焦区域H_(2)S分布情况以及运行调整对H_(2)S和NO_(x)的影响情况,指导锅炉运行,在某300 MW等级电站锅炉上安装了水冷壁气氛在线监测装置,系统研究了炉内近壁面H_(2)S、CO等还原性组分的生成规律及运行调整对炉内氛围的影响。结果表明:(1)在高负荷时炉内H_(2)S、CO整体浓度较高,并且负荷越高,腐蚀倾向越严重。(2)负荷在由高向低下降的过程中,存在一临界负荷(40%BMCR),当降至此临界负荷时,壁面气氛由还原性气氛开始转化为氧化性气氛。该炉易发生高温腐蚀的负荷范围为60%~100%。(3)总体上壁面H_(2)S与CO表现出正相关性,而H_(2)S与SO_(2)呈负相关性,但同时壁面各组分间又呈现出一定的独立性。(4)结焦区域H_(2)S平均浓度比非结焦区域高出537×10^(-6)(体积分数,下同),这与结焦区域水冷壁相较于非结焦区域水冷壁腐蚀更严重的现象一致。(5)关闭燃尽风投运层数、增加运行氧量,可以显著降低H_(2)S浓度,最高降幅可达91.4%,但H_(2)S浓度降低会引起NO_(x)增加,关一层燃尽风,NO_(x)平均上涨109 mg/m^(3)。建议在实际运行中,需要平衡好这对矛盾。

In order to reveal the concentration distribution of H_(2)S in the boiler water wall at different loads,the change of the atmosphere when the load changes,the relationship between H_(2)S and the furnace components CO and SO_(2),the distribution of H_(2)S in the coking area and the influence of operation adjustment on H_(2)S and SNO_(x),and to guide the operation of the boiler,an on-line monitoring device for the water wall atmosphere was installed on a 300 MW level power plant boiler.The formation law of reducing components such as H_(2)S and CO near the furnace wall and the influence of operation adjustment on the atmosphere in the furnace were systematically studied.The results show that:(1)The overall concentration of H_(2)S and CO in the furnace is higher at high load,and the higher the load,the more serious the corrosion tendency.(2)When the load decreases from high to low,there is a critical load(40%BMCR).When the load decreases to this critical load,the wall atmosphere begins to change from reducing atmosphere to oxidizing atmosphere.The furnace is prone to high temperature corrosion load range of 60%~100%.(3)On the whole,H_(2)S and CO on the wall showed a positive correlation,while H_(2)S and SO_(2)showed a negative correlation,but at the same time showed a certain degree of independence.(4)The average concentration of H_(2)S in coking area is 537×10^(-6) higher than that in non-coking area,which is consistent with the phenomenon that the corrosion of water wall in coking area is more serious than that in non-coking area.(5)Turning off the number of over-fire air layers and increasing the operating oxygen can significantly reduce the concentration of H_(2)S,with a maximum decrease of 91.4%.However,the decrease of H_(2)S concentration will cause the increase of SNO_(x).Turning off one layer of over-fire air can increase SNO_(x) by an average of 109 mg/m^(3).It is suggested that this contradiction needs to be balanced in actual operation.