糠醛渣流化床燃烧过程中床料粘结机理研究

Mechanism of Bed Material Agglomeration During Fluidized Bed Combustion of Furfural Residues

为了研究糠醛渣流化床燃烧过程中床料粘结机理,在小型鼓泡流化床实验装置上,以石英砂作为床料,对糠醛渣在不同温度(750、800、850、900℃)下燃烧过程中床料的粘结现象进行了实验研究并对其机理进行了探讨。实验结果表明:在实验时间范围内(6h),只有900℃工况出现了床料粘结失流现象。通过对实验后的床料和结团分别进行X射线衍射(XRD)和扫描式电子显微镜/射线能谱仪(SEM/EDS)分析表明,不同温度下床料粘结失流特性不同的根本原因在于糠醛渣灰中主要碱金属钾盐存在的形式不同,750℃为KCl,800℃为KCl和K2SO4混合物,800℃以上则为含碱金属钾的复杂硅铝和硅钙化合物,而复杂化合物的熔点在900℃左右。因此,说明含碱金属钾的复杂硅铝和硅钙化合物熔融对糠醛渣流态化燃烧床料粘结失流具有重要作用。实验结果对糠醛渣流化床锅炉燃烧温度的选取具有较重要的参考价值。

Experiments are carried out in a bench-scale bubbling fluidized bed with silica sand at different bed temperature（750,800,850,and 900℃）to study the mechanism of bed material agglomeration during fluidization combustion of furfural residues.The results show that bed agglomeration and defluidization only take place at 900 ℃ during the experiment period（6hours）.XRD and SEM/EDS analyses on bed materials and agglomerate samples discharged from the bed after combustion show that the main reason that makes the fluidized bed have different characteristics of bed agglomeration and defluidization is the different composition of alkali metal potassium salt in furfural residue ash at different bed temperature.The main composition of alkali metal potassium salt is KCl at 750℃,a mixture of KCl and K2SO4 at 800℃,and a complex containing alkali metal potassium silicate compounds with Al and Ca above 800℃.The melting point of the complex is about 900℃.Thus,the melting of this complex compounds plays an important role in agglomeration and defluidization during combustion of furfural residue in fluidized bed.These results have certain reference value for choosing combustion temperature in furfural residue fluidization bed boiler.