基于CCSEM分析的煤中含铁矿物分布对结渣特性的影响研究

CCSEM-based investigation on effect of distribution characteristics of iron-bearing minerals in coal on slagging behaviors

含铁矿物是煤中的主要致渣矿物。为优化电厂燃煤选配方案,利用先进的计算机控制扫描电镜(CCSEM)技术对Fe_(2)O_(3)质量分数相近,但结渣倾向差别较大的2种电厂动力用煤含铁矿物的分布特性进行对比分析。其中A煤燃烧时锅炉出现明显结渣问题,而B煤燃烧时锅炉结渣不明显。结果表明:A煤和B煤中具有相似的含铁矿物种类,但是A煤中分布在黄铁矿中的Fe_(2)O_(3)质量分数比B煤高约12%,分布在内在矿磁黄铁矿和内在铁铝硅酸盐中的Fe_(2)O_(3)质量分数分别比B煤高约8%和5%;A煤中更高的黄铁矿和内在含铁矿物分布比例是导致其结渣倾向强于B煤的主要原因;虽然B煤中CaO质量分数明显高于A煤,但是煤中Ca的共生特性对含铁矿物结渣的协同贡献并不明显。为降低炉膛结渣风险,采用低NO_(x)燃烧技术时,应当控制入炉煤黄铁矿和磁黄铁矿含量。

Iron-bearing minerals are key slag-inducing minerals in coal.To optimize the coal blending scheme,comparison study on distribution characteristics of iron-bearing minerals between coal A and coal B was carried out by a computer–controlled scanning electron microscope(CCSEM).Coal A and coal B have similar Fe_(2)O_(3) mass fraction in the ash,while coal A has much higher ash slagging propensity than coal B.The research results show that,Coal A and coal B have similar iron-bearing minerals species.However,coal A has 12%higher mass fraction of Fe_(2)O_(3) in pyrite than coal B.The mass fraction of Fe_(2)O_(3) in included pyrrhotite and included iron aluminosilicate in coal A is 8%and 5%higher than that in coal B,respectively.Higher mass fraction of pyrite and included ironbearing minerals in coal A than coal B is dominant reason for severe ash slagging of coal A.Though coal B has higher mass fraction of CaO in the ash than coal A,combination of Ca and iron-bearing minerals seems do not worsen iron-bearing mineral slagging problem.In order to reduce the risk of ash slagging,the mass fraction of pyrite and pyrrhotite in coal should be controlled when using de-NO_(x) combustion technology.