Experimental study on dynamic release and transformation of sulfur during pyrolysis of Shanxi high-sulfur anthracites based on MFBRA and XPS
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摘要: 利用微型流化床反应分析仪(MFBRA),开展了两种山西高硫无烟煤的热解脱硫实验。通过对含硫气体动态释放的在线快速检测、结合原料煤和热解半焦的形态硫以及含硫组分的X射线光电子能谱(XPS)分析,研究了含硫气体释放特征及相应半焦含硫组分在热解过程中的变化,重点探讨了高硫无烟煤在氢气气氛下各含硫组分的动态释放和相互转化过程及规律。研究结果表明,高硫无烟煤有机硫含量越高,在氢气气氛下的脱硫效率越高;两种高硫无烟煤在氢气气氛下热解硫释放均呈现两个阶段,对应热解脱硫峰值温度分别为530−560 ℃和812−830 ℃。第一阶段由黄铁矿的还原反应引起,第二阶段以有机硫裂解为主;在低温热解条件下高硫无烟煤中无机硫会向有机硫转变,而在较高温度下发生不同形态有机硫之间的迁移。本研究结果将为高硫无烟煤制备低硫煤的技术开发提供方法指导和基础数据。Abstract: Pyrolytic desulfurization of two Shanxi high-sulfur anthracites was investigated experimentally under hydrogen atmospheres using a micro fluidized bed reaction analyzer (MFBRA), the dynamic release behavior of sulfur-containing gas during pyrolysis was characterized by a rapid online gas analyzer, and the transformation between sulfur-containing components in the resultant char was analyzed based on morphological and XPS characterizations. The results show that the dynamic release of sulfur-containing gas features two intensity peaks at 530−560 ℃ and 812−830 ℃, respectively, indicating that the sulfur release proceeds by two subsequent processes: the reduction reaction of pyrite and the organic sulfur decomposition. The migration from inorganic to organic sulfur occurs predominately at lower temperatures, while the transformation between different forms of organic sulfur components is dominant at higher temperatures. Overall, the anthracite coal with a higher organic sulfur content has a higher sulfur removal efficiency in the hydrogen atmosphere. The research results provide the essential data supporting the development of highly efficient pyrolysis desulfurization technology for clean and efficient utilization of high sulfur anthracite coal resources.
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表 1 煤的工业分析和元素分析
Table 1 Proximate and ultimate analyses of raw coal samples
Sample Proximate analysis w/% Ultimate analysis w/% Ad Vdaf FCdaf Cdaf Hdaf Ndaf St,d ST 17.53 9.67 72.80 79.80 3.60 0.92 4.19 LDS 21.79 8.92 69.29 85.61 3.81 1.01 6.30 A:ash;V:volatile;FC:fixed carbon;C:carbon;H:hydrogen;O:oxygen;N:nitrogen; S:sulfur; d: dry basis ;
daf: dry-ash-free;t:total sulfur表 2 煤中形态硫分析
Table 2 Analyzed sulfur forms of raw coal samples
Sample Content w/% St,d Sp,d Ss,d So,d ST 4.19 1.96 0.13 2.10 LDS 6.30 1.67 0.06 4.57 t:total sulfur;p:pyrite sulfur;s: sulfate sulfur;o: organic sulfur; d:dry basis 表 3 XPS分析所得ST煤及其半焦表面的硫形态和总硫
Table 3 Sulfur forms and total sulfur of ST coal and char determined by XPS
Pyrolysis condition w/% sulfidic thiophenic sulfoxide sulfones sulfate total sulfur ST raw coal 0.16 0.8 0.42 − 0.47 1.85 ST-450 ℃-H2 0.29 0.85 0.43 − 0.28 1.85 ST-550 ℃-H2 0.23 1.39 0.45 0.1 0.21 2.38 ST-650 ℃-H2 0.16 0.76 0.26 − 0.26 1.44 ST-750 ℃-H2 0.74 0.14 − 0.28 0.04 1.2 ST-850 ℃-H2 0.15 0.21 0.02 0.15 0.18 0.71 -
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