Changes of Zhundong coal properties by hydrothermal upgrading and its impacts on CO2 gasification
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摘要: 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CO2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CO2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。Abstract: 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.
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Key words:
- Zhundong coal /
- hydrothermal upgrading /
- coal properties /
- sodium removal /
- CO2 gasification
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表 1 煤样的工业分析、元素分析
Table 1 Proximate and ultimate analysis of samples
Sample Proximate analysis w/% Ultimate analysis wdaf/% Qnet, d
/ (MJ·kg-1)Atomic ratio (daf) Mad Ad Vd FCd C H O* N S H/C O/C Raw 10.95 5.61 31.90 62.49 73.95 3.97 20.90 0.54 0.64 25.52 0.644 0.212 H150 9.02 5.15 31.86 62.99 74.42 3.92 20.77 0.56 0.40 25.59 0.632 0.209 H200 5.56 5.43 31.15 63.42 74.52 3.90 20.62 0.58 0.38 25.60 0.628 0.208 H250 4.82 5.03 29.86 65.11 74.92 3.80 20.38 0.58 0.32 25.76 0.608 0.204 H300 4.24 5.22 28.48 66.31 76.31 3.79 19.02 0.60 0.29 26.28 0.595 0.187 H350 2.41 5.38 25.36 69.26 78.47 3.73 16.98 0.59 0.23 27.08 0.570 0.162 *:by difference 表 2 焦样的XRD参数
Table 2 XRD parameters of coal chars
Sample 2 θ002/(°) 2 θ100/(°) d002/nm Lc/nm La/nm Raw 24.93 43.89 0.357 1.556 1.897 H150 25.04 43.79 0.355 1.557 2.299 H200 25.17 43.95 0.354 1.705 2.376 H250 25.26 43.84 0.352 1.850 2.382 H300 25.34 44.06 0.351 1.905 2.389 H350 25.58 43.44 0.348 2.243 2.411 -
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