Oxy-CFB燃烧高钠煤时受热面积灰机理研究

准东煤储量丰富、开采成本低、反应活性好，近年来日益受到关注。然而其钠含量高，在燃烧过程中极易造成受热面积灰和腐蚀，影响设备运行安全和效率。循环流化床富氧燃烧（Oxy-CFB）技术结合循环流化床燃烧和富氧燃烧的优势，是一种极具前景的CO2减排技术。项目将基于管式炉试验和三元相图理论研究高钠煤在Oxy-CFB燃烧气氛下的钠迁移转化规律。搭建Oxy-CFB热态试验台，结合积灰过程的可视化技术，研究高钠煤Oxy-CFB燃烧时受热面灰沉积机理，研究添加剂对减轻积灰的影响规律和机制。基于Euler-Lagrange模型，建立经详细实验数据验证的受热面飞灰沉积过程数学模型。运用密度泛函理论探究飞灰中矿物质的反应活性、钠对矿物质间相变的作用规律，揭示影响灰熔融特性的微观机理。期望通过本项目的工作促进高钠煤热转化利用的理论研究，并深入揭示Oxy-CFB燃烧条件下高钠煤中钠的迁移转化规律和受热面积灰机理。

In recent years, the Zhundong coal has attracted great attention due to its unique advantages such as abundant storage, low mining cost and excellent reactivity. However, the high sodium existed in the Zhundong coal may easily cause the ash deposition and corrosion of the heat transfer surface during the combustion process and has negative effects on the equipment operation and efficiency. The oxy-fuel circulating fluidized bed (Oxy-CFB) combustion technology, which combines the advantages of the CFB combustion technology and the oxy-fuel combustion technology, exhibits great potential to reduce the CO2 emission. Based on the tube furnace test and ternary phase diagram theory, this project conducts the research of the sodium migration patterns under the Oxy-CFB combustion atmosphere. Combined with the visualization technology of the ash deposition, an Oxy-CFB hot test facility is established to study the ash deposit mechanism of the heat transfer surface and effects of additives on the ash reduction during the high-sodium coal combustion process. Besides, the Euler-Lagrange approach is adopted to build a comprehensive and experimentally-validated mathematical model for the ash deposition of the heat transfer surface. The density functional theory is used to explore the reactivity of the mineral substance in the ash, the influence of sodium on the phase change rules of different mineral substances, and the micromechanism of the ash fusion characteristics. This project is expected to improve the theoretical research on the thermal conversion of the high-sodium coal and reveal the sodium migration patterns and ash deposition of the heat transfer surface under the Oxy-CFB combustion atmosphere.