Rapid gasification of nascent char in steam atmosphere during the pyrolysis of Na- and Ca-Ion-exchanged brown coals in a drop-tube reactor
Rapid gasification of nascent char in steam atmosphere during the pyrolysis of Na- and Ca-Ion-exchanged brown coals in a drop-tube reactor
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DOI：
10.1021/ef900235e
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发表时间：
2009-07
期刊：
影响因子：
5.3
通讯作者：
O. Mašek;S. Hosokai;K. Norinaga;Chun-Zhu Li;J. Hayashi
中科院分区：
文献类型：
--
作者：
O. Mašek;S. Hosokai;K. Norinaga;Chun-Zhu Li;J. Hayashi
最近几项关于煤的原位水蒸气气化的研究表明，从褐煤的快速热解得到的焦炭有可能进行极快的水蒸气气化。通过将新生成的焦炭暴露于蒸汽中，即在焦油析出之后(温度范围>；600°C)，但在脱挥发之前(<；900°C)，可以实现前所未有的焦炭水蒸气气化速率。在本研究中，我们对离子交换洛伊阳褐煤进行了快速热解实验，即Na/Ca含量为0.001 wt%的H型煤、Na含量为2.8wt%的Na型煤和Ca含量为3.2wt%的钙型煤。这些样品在常压滴管反应器中进行热解，温度为900℃，进口水蒸气浓度为50vol.在不同煤种的碳基上，钠型煤和钙型煤的热解残炭率分别为12%和33%，仅占煤的18%和53%。
Several recent studies on in situ steam gasification of coal suggest a possibility of extremely fast steam gasification of char from rapid pyrolysis of pulverized brown coal. The unprecedented rate of char steam gasification can be achieved by exposing nascent char, that is, after tar evolution (temperature range >600 °C), but before devolatilization (<900 °C), to steam in the presence of Na and/or Ca dispersed in/on the char. In this study, we conducted rapid pyrolysis experiments using ion-exchanged Loy Yang brown coal samples, that is, H-form coal with Na/Ca contents <0.001 wt %, Na-form coal with Na content = 2.8 wt % and Ca-form coal with Ca content = 3.2 wt %. These samples were pyrolyzed in an atmospheric drop-tube reactor at a temperature of 900 °C, inlet steam concentration of 50 vol. %, and a particle residence times of 2.8 s. The char yields from the pyrolysis of Na-form and Ca-form coals were as low as 12 and 33% on the respective coal carbon bases, and accounted for only 18 and 53% of the cha...