A study was undertaken of the air preheater ash deposit in a 140 MW coal-fired traveling-grate boiler. Several ash samples were collected in the selected regions of the air preheater along with samples of the feed coal. The ash samples were examined using combination of ash X-ray fluorescence (XRF) and X-ray diffraction (XRD) analysis to determine the chemistry and mineralogy. The ash samples were also examined using scanning electron microscopy and energy dispersive spectrum (SEM-EDS) analysis to determine the microstructure and phase constitution. The analysis results showed that the sulfur content of ash deposits varied with the temperature of the gas flue. The higher amounts of sulfur in ash deposits proved to be sulfates. It appeared that sulfuric acid was a driving factor in the formation of the deposition. The sulfates probably acted as cementing agent, giving the deposit its hardness and thickness.

中文翻译：

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燃煤移动炉排锅炉管式空气预热器灰渣形成的研究

对一台140 MW燃煤移动炉排锅炉中的空气预热器灰分沉积物进行了研究。在空气预热器的选定区域中收集了一些灰分样品以及进料煤的样品。使用灰分X射线荧光（XRF）和X射线衍射（XRD）分析的组合检查灰分样品，以确定化学和矿物学。还使用扫描电子显微镜和能量色散谱（SEM-EDS）分析检查了灰分样品，以确定其微观结构和相组成。分析结果表明，灰烬沉积物中的硫含量随烟气温度的变化而变化。灰渣中较高含量的硫被证明是硫酸盐。似乎硫酸是沉积物形成的驱动因素。