Comprehensive knowledge concerning the behavior of phosphorus (P) during combustion is necessary to enable more efficient recovery of P from combustion ashes for agricultural purposes. To this end, parameters that influence the distribution and speciation of P in combustion ashes are important because they may influence which ash fractions are suitable for P recovery. This study aims to determine the fate of P as a result of fuel ash composition and chemical association in the fuel during fluidized bed combustion by a systemic review of previous work. The synthesis was performed by comparing scanning electron microscopy–energy-dispersive X-ray spectroscopy and X-ray diffraction chemical analyses of bed ash, fly ash particles, and deposits from fluidized bed combustion of different blends of P-poor (logging residues or wheat straw) and P-rich (sewage sludge, dried distiller’s grain with solubles, or phosphoric acid) fuels and additives. The blends were produced to have a similar ash composition but with a different P source. The distribution of P among ash fractions indicated that P is mainly found in the coarse ash fractions (bed and cyclone ash), irrespective of fuel ash composition or chemical association in the fuel. The chemical speciation of P in coarse ash fractions differed between biomass blends containing sewage sludge compared to blends with phosphoric acid or dried distiller’s grain with solubles. Phosphates in the ash from the two sewage sludge blends included predominantly Ca with minor inclusion of other cations. In contrast, ashes from the blends with phosphoric acid or dried distiller’s grain with solubles contained phosphates with a significant amount of K, Ca, and Mg. The difference in phosphate speciation could not solely be explained by the combustion conditions and the elemental composition of the ash fractions. These results show that it is necessary to consider the chemical association of P in the fuel to predict the type of phosphates that will form in fluidized bed combustion ashes.

中文翻译：

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生物质和污泥流化床燃烧中磷命运的系统评价

必须有关于燃烧过程中磷（P）行为的全面知识，才能更有效地从农业用煤灰中回收磷。为此，影响P在燃烧灰烬中的分布和形态的参数很重要，因为它们可能会影响适合P回收的灰分。本研究旨在通过系统回顾以前的工作来确定流化床燃烧过程中燃料灰分组成和燃料中化学缔合的结果。合成是通过比较扫描电子显微镜–能量色散X射线光谱学和床灰，粉煤灰颗粒的X射线衍射化学分析进行的，以及贫磷（伐木残渣或麦秸）和富磷（污水污泥，干酒糟含可溶物或磷酸）燃料和添加剂的不同混合物流化床燃烧产生的沉积物。产生的共混物具有相似的灰分组成但具有不同的P源。P在灰分中的分布表明，P主要存在于粗灰分（床和旋风灰）中，与燃料中的灰分组成或化学缔合无关。含污水污泥的生物质混合物与含磷酸的混合物或干酒糟含可溶物的混合物相比，粗灰分中P的化学形态不同。两种污水污泥混合物中的灰分中的磷酸盐主要包含钙，而其他阳离子则较少。相反，与磷酸共混的烟灰或含有可溶物的干酒糟含有的磷酸盐中含有大量的K，Ca和Mg。磷酸盐形态的差异不能仅通过燃烧条件和灰分的元素组成来解释。这些结果表明，有必要考虑燃料中P的化学缔合，以预测将在流化床燃烧灰烬中形成的磷酸盐的类型。