准东煤水热提质过程中煤质特性变化对CO_2气化影响

选取准东高钠煤为研究对象,在高压反应釜中进行了不同温度(150-350℃)下的水热提质处理实验,依托电感耦合等离子体质谱(ICP-MS)、氮气等温吸附模型(BET)和X射线衍射(XRD)等技术,分析了煤样的煤质特性变化以及对CO_2气化的综合影响规律。结果表明,水热提质处理后煤样成熟度增加,煤阶上升,钠的脱除效果显著,在300-350℃时脱除率均大于95%。煤焦化学结构致密、有序、稳定;煤样CO_2气化曲线向高温区偏移,气化活性指数呈下降趋势且300-350℃时下降明显。水热提质过程中煤样气化反应活性受到煤阶、碱金属钠含量、物理孔隙结构、化学微晶结构等多个因素的综合影响。

Changes of Zhundong coal properties by hydrothermal upgrading and its impacts on CO2 gasification

The Zhundong high sodium coal was hydrothermally upgraded at 150-350℃ in an autoclave. The inductively coupled plasma mass spectrometer (ICP-MS), nitrogen adsorption isotherm (BET) and X-ray diffraction (XRD) were used to investigate the changes of coal properties and the impacts on the CO₂ gasification characteristics. The results indicate that the coal quality is increased after the hydrothermal upgrading. The removal effect of sodium is obvious, reaching to more than 95% at 300-350℃. The pore structure of the chars changes significantly, the specific surface area and total pore volume increase initially at 150-300℃ and then decrease at 300-350℃. The crystalline structure tends to be aromatic and graphitized, and the chemical structure becomes dense, orderly and stable. Additionally, the gasification reactivity exhibits a decreasing trend, especially for the chars treated at 300-350℃. The CO₂ gasification reactivity during the process of hydrothermal upgrading is comprehensively influenced by different factors containing coal rank, sodium content, physical pore structure and chemical microcrystalline structure.