燃用准东煤电站锅炉灰沉积形成过程中的矿物演变与热力学模拟

选取某350 MW电站锅炉燃烧准东混煤,得到锅炉换热面灰沉积样品,主要借助XRD等手段分析了各处灰沉积物矿物形成过程,并通过Factsage 5.2从热力学平衡角度给出理论支持。结果表明,高温区域换热面灰沉积形成主要由于钠长石、钙长石等矿物在高温下经复杂变化形成低温共熔物,黏附烟气中固体颗粒而形成坚硬块状沉积物;低温区域换热面主要由于烟气中硫的沉积而发生酸性腐蚀,沉积物主要晶相为硫酸钙;省煤器换热面主要由于烟气携带的非晶态物形成松散型积灰。Factsage计算结果与实际灰样组成大致吻合,能够帮助分析灰沉积物中矿物质的转化规律。

Mineral conversion and thermodynamic simulation of ash deposition during Zhundong coal combustion in boiler of thermal power plant

Zhundong coal blending was combusted in a 350 MW boiler. Ash deposits samples at different heat transfer surface (HTS) were collected to investigate mineral conversion of each sample. Thermodynamic equilibrium calculation was carried out to give theoretical support by virtue of Factsage 5.2. Different mechanism of each HTS was concluded as follows. At high temperature HTS, albite, anorthite and other phases help eutectics precipitate take shape, which adheres to fly ash particles and forms indurate bulk ash deposits. At low temperature HTS, sulphur-containing species are condensed from flue gas to form deposits with evidence that the main crystalline phase is anhydrite. At economizer HTS, The deposits consisted of amorphous phases carried by flue gas are loosely bonded. Calculated results by Factsage basically agreed with the phase composition of actual samples and are of assistance to mineral conversion analyses.