准东煤掺烧油页岩后矿物质的转化迁移研究

研究准东煤和油页岩混合燃料在100 MW锅炉燃烧过程中的矿物质演变规律,解决火力发电厂大比例和大规模掺烧准东煤引起的沾污和结渣问题。对现场试验收集的入炉煤、飞灰和炉渣样品进行化学分步萃取、XRD、灰成分等分析。结果表明,在100 MW机组锅炉燃用准东煤掺混15%油页岩的混合燃料,油页岩灰分中镶嵌或者包裹的可燃物燃烧后,炉渣将形成多孔和酥松形态,从炉渣的结构方面缓解准东煤引起的炉膛结渣问题。掺混15%油页岩后,燃烧过程中碱金属和碱土金属基本不挥发,炉渣中Na_2O、MgO、CaO和SO_3的含量较准东煤分别降低了2.07%、3.42%、15.08%和10.5%;飞灰中Na_2O、MgO、CaO和SO_3的含量也较准东煤明显下降。同时炉渣和飞灰中的钠主要为钠长石,钾在掺烧前后都以KAl_2(Si_3Al)O_(10)(OH)_2存在。在炉膛中碱土金属的碳酸盐和硫酸盐分解后,大部分转化为钙黄长石。油页岩通过降低碱金属和碱土金属含量及改变其存在形态,解决了准东煤引起的炉膛结渣和受热面沾污的问题。

Mineral transformation of Zhundong coal and oil shale during combustion process

The problem of fouling and slagging could be solved by blended 15% oil shale in the combustion of Zhundong coal. The XRD and ash composition were used to study the ash slagging and mineral conversion of Zhundong coal by blending oil shale. The results show that there are large number of porous in slag. The contents of Na2O, MgO, CaO and SO3 in the slag reduce 2.07%, 3.42%, 15.08% and 10.5% than Zhundong coal, respectively, the alkali and alkaline earth metals were not volatilized during combustion with 15% oil shale. The contents of Na2O, MgO, CaO and SO3 in fly ash were also significantly decreased. The soudium in the slag and fly ash is mainly in the form of albite. The potassium is present in KAl2(Si3Al)O10(OH)2. Most of the alkaline earth metal react into aluminosilicates. A small amount of fine-grained alkaline earth metal oxides are bring into fly ash by flue gas. In addition, oil shale can effectively alleviate slagging problem through reducing the content of alkali and alkaline earth metals and transforming its form.