床料对生物质流化床燃烧黏结特性的影响

The Influence of Bed Materials on Agglomeration Characteristic During Fluidized-bed Combustion of Bio-fuels

在5 kW鼓泡流化床实验装置上,以循环流化床燃煤灰渣、煤矸石灰渣作为床料,进行了麦秆成型燃料燃烧黏结特性研究。实验表明:900℃工况下,相对于石英砂床料,以上两种床料均能够有效地控制生物质流化床燃烧过程中的黏结现象。结合SEM-EDX分析结果与多相平衡反应计算分析,应用流化床燃煤炉渣、煤矸石灰渣为床料控制麦秆流化床燃烧黏结现象的机理相似。相对于石英砂,两种床料中均含有较高含量的硫元素、较高含量的铝元素,在麦秆燃烧过程中,床料中的铝元素、硫元素会与麦秆灰中高含量的钾元素形成高熔点的物质,有利于减轻麦秆流化床燃烧黏结现象;另外,黏结物中相对高含量的碱土金属元素使得黏结物的熔点提高,有利于控制麦秆流化床燃烧黏结现象。

The agglomeration characteristics during combustion of wheat stalk pellet with two kinds of bed materials including fluidized bed coal slag and coal gangue ash were investigated in a bench scale bubbling fluidized bed. The results indicate that compared with silica sands, both bed materials can prevent the agglomeration phenomenon at 900℃. Combining the data from scanning electron microscopy （SEM） and energy dispersive X-ray（EDX）and the result of phase equilibrium calculations, the control mechanisms of two kinds of bed materials are similar. The higher content of S and Al in fluidized bed coal slag and coal gangue ash can react with K in wheat stalk during fluidized bed combustion, the resultants have higher melting points which are conducive to prevent the agglomeration phenomenon. In addition, the higher content of Mg and Ca in coal gangue ash and fluidized bed coal slag can improve the melting point of the agglomerates.