飞灰中晶体矿物及非晶体与残碳分布的关系

摘要

In order to study the distribution regularities of fly ash in circulating fluidized bed boilers, the fly ash with different densities at the same particle size was analyzed using X-ray diffraction (XRD), Maud (whole pattern fitting) and scanning electron microscope (SEM). The distribution regularities of crystalline minerals, amorphous glass and residual carbon in fly ash were investigated. The results show that the mass fraction of the residual carbon in fly ash varied with density. For the fly ash with small densities, unburned carbon would form due to the fly ash's short residence time in the circulating fluidized bed, so the residual carbon content was high. On the other hand, the fly ash with large densities showed a low carbon content because of its long residence time in the circulating fluidized bed (reaching full combustion). The residue carbon content reached the maximum in the fly ash with density ranging from 1.85×103 kg/m3 to 2.15×103 kg/m3. The crystal minerals existed uniformly in the fly ash with different densities. The crystalline minerals, amorphous glass and residual carbon showed dependent distribution patterns. The residual carbon coexisted with Si-Al amorphous minerals in the fly ash. The results provide the basis for the utilization of fly ash in circulating fluidized beds.%为了研究循环流化床飞灰中残碳的分布规律,以各个粒径下分成不同密度段的飞灰作为研究对象,采用X射线衍射仪(XRD),全谱拟合(Maud)和扫描电子显微镜(SEM)对其结构进行了分析,得到了飞灰中晶体矿物及非晶玻璃相与残碳分布的规律.结果表明:循环流化床飞灰的残碳质量分数分布随密度呈现一定的规律;小密度飞灰由于在循环流化床中停留时间短形成未燃碳而导致含碳量高,大密度飞灰在床内停留时间长而燃烧充分因此含碳量低,1.86×103～2.15×103 kg/m3密度段内的飞灰残碳质量分数达到峰值;晶体矿物在各个密度段飞灰中均匀存在;飞灰中晶体矿物、非晶玻璃相与残碳并非独立分布,残碳与硅铝类非晶玻璃相共存.该结果可为循环流化床中飞灰的利用提供依据.