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针对我国新疆高碱煤燃烧过程中的强沾污、结渣特性,对某300MW亚临界高碱煤锅炉炉内各受热面的沾污灰样进行了XRF和SEM-EDX分析.结果表明:在800~1 100℃烟气温度区间内,灰样中CaO、MgO和SO3的质量分数较高;当烟气温度降低至600~800℃时,灰样中Na2O、Fe2O3和SO3的质量分数较高,Na2SO4、CaSO4和NaFeSO4等物质是导致高碱煤燃烧过程中高温对流受热面发生严重沾污的主要原因;669~915℃烟气温度区间内的灰样发生初始熔融的温度及其所对应的液相质量分数要高于其他部位的灰样;灰样C颗粒表面附着粒径为2~4μm的富含Na、S的Na2SO4等颗粒,而钠的硫酸盐在高温下具有较高的黏性和较低的熔点,这是导致该温度下发生严重沾污的主要原因之一.
XRF and SEM-EDX analysis of the soiled ash samples of each heating surface in a 300MW subcritical overbased coal-fired boiler for strong soiling and slagging in Xinjiang high alkali coal combustion process showed that The mass fraction of CaO, MgO and SO3 in the ash sample is higher in the temperature range of 800-1 100 ℃. When the flue gas temperature is reduced to 600-800 ℃, the mass fraction of Na2O, Fe2O3 and SO3 in the sample is higher , Na2SO4, CaSO4 and NaFeSO4 are the main reasons causing serious contamination of the high temperature convection heating surface during the combustion of high-alkali coal. The initial melting temperature of the ash sample in the temperature range of 669 ~ 915 ℃ and its corresponding The mass fraction of the liquid phase is higher than that of the other parts of the ash sample; the ash sample C particle surface with particle size of 2 ~ 4μm Na, S Na2SO4 and other particles rich in sodium sulfate at high temperatures with high viscosity And lower melting point, which is one of the major causes of serious contamination at this temperature.