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Vaporization behavior of boron from standard coals in the early stage of combustior

机译：燃烧初期标准煤中硼的汽化行为

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摘要

Boron-containing compounds have been listed as one of environmentally hazardous substances in Japan since 2001, and known to condense in coal fly ash particles during coal combustion and coal fly ash for mation in coal-fired electric power stations. So far, the authors have revealed that the speciation of boron-containing compounds in coal fly ash particles is mostly a calcium orthoborate or pyroborate. In this research, the speciation of boron compounds in standard coals and their char generated by laboratory-scale combustion test has been investigated by using a microwave-assisted acid digestion method and a Magic-Angle-Spinning Nuclear Magnetic Resonance (MAS-NMR) in order to reveal the vaporization behavior of boron in standard coals during combustion at relatively low temperature. Three isolated peaks are observed in ~nB MAS-NMR spectra of standard coals, and all of them are attributed to four-oxy gen-coordinated boron atom. Around 50% of boron vaporizes even though heating condition is 200 °C and O_2 = 25%, and the percentage of vaporization reaches higher value than 80% at 400°C and O_2 = 25%. The remaining boron contents in ash components are relatively small, and it suggests that most of boron in standard coals exist with relatively volatile carbon contents, and they volatilize in the very early stage of coal combustion.
机译：自2001年以来，含硼化合物在日本已被列为对环境有害的物质之一，已知在燃烧煤时会在煤粉煤灰颗粒中凝结，并在燃煤发电站进行粉煤灰凝结。到目前为止，作者们已经揭示了粉煤灰颗粒中含硼化合物的形态主要是原硼酸钙或焦硼酸钙。在这项研究中，通过微波辅助酸消解法和魔角旋转核磁共振（MAS-NMR）技术研究了标准煤中硼化合物的形态及其实验室规模燃烧试验产生的焦炭。为了揭示标准煤中硼在较低温度下燃烧时的汽化行为。在标准煤的〜nB MAS-NMR谱图中观察到三个孤立的峰，所有这些峰均归因于四氧配位的硼原子。即使在200°C和O_2 = 25％的加热条件下，约有50％的硼汽化，而在400°C和O_2 = 25％时，汽化的百分比值高于80％。灰分成分中剩余的硼含量相对较小，这表明标准煤中的大多数硼以相对易挥发的碳含量存在，并且在燃煤的早期就挥发。

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  • 来源
    《Fuel》 |2011年第4期|p.1408-1415|共8页
  • 作者

    Shunsuke Kashiwakura; Takafumi Takahashi; Tetsuya Nagasaka;

  • 作者单位

    Graduate School of Environmental Studies, Tohoku University, Sendai, Miyagi 980-8579, Japan;

    Advanced Research Center of Nippon Steel Corporation, 20-1 Shintomi, Futtu, Chiba 293-8511, Japan;

    Graduate School of Environmental Studies, Tohoku University, Sendai, Miyagi 980-8579, Japan;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    coal; boron; volatility; mas-nmr;

    机译：煤;硼;挥发性;质量核磁共振;

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