Effects of pretreatment in steam on the pyrolysis behavior of Loy Yang brown coal
Effects of pretreatment in steam on the pyrolysis behavior of Loy Yang brown coal
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DOI：
10.1021/ef0502406
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发表时间：
2006-01-01
期刊：
影响因子：
5.3
通讯作者：
Li, CZ
中科院分区：
文献类型：
--
作者：
Zeng, C;Favas, G;Li, CZ
维多利亚褐煤的脱水/干燥将是未来褐煤利用过程的一个组成部分，旨在减少温室气体排放。研究了褐煤在水蒸汽存在下的热预处理对其后续热解行为的影响。在加压蒸汽和惰性气氛中对维多利亚（Loy Yang）褐煤进行热预处理。在丝网反应器中考察了这些预处理煤样的热解行为。虽然在高于250摄氏度的温度下在蒸汽中的预处理增加了蒸汽处理的煤的炭产率，但如果还考虑在蒸汽中的预处理期间的重量损失，则其不影响在1000摄氏度s（-1）下的总体热解炭产率。然而，在水蒸气存在下的预处理后，焦油产率显着降低。焦油的紫外荧光光谱显示，从蒸汽处理的煤中释放的大的芳香族系统仅受蒸汽中的预处理的影响，如果处理温度非常高（例如350摄氏度）。在褐煤的蒸汽预处理过程中，NaCl的损失和高压的使用不是观察到的焦油产率变化的主要原因。含氧结构如醚、酯和羧酸盐在水蒸汽存在下的预处理过程中的水解对这些含氧结构在预处理和随后的热解过程中的命运起着重要作用，导致褐煤热解行为的变化。
Dewatering/drying of Victorian brown coal will be an integral part of future brown coal utilization processes aimed at the reduction of greenhouse gas emissions. This study aims to investigate the effects of the thermal pretreatment of brown coal in the presence of steam/water on its subsequent pyrolysis behavior. A Victorian (Loy Yang) brown coal was thermally pretreated in pressurized steam and inert atmospheres. The pyrolysis behavior of these pretreated coal samples was investigated in a wire-mesh reactor. While the pretreatment in steam at temperatures higher than 250 degrees C increased the char yield of the steam-treated coal, it did not affect the overall pyrolysis char yield at 1000 degrees C s(-1) if the weight loss during the pretreatment in steam was also considered. However, the tar yield decreased significantly after the pretreatment in the presence of steam. The UV-fluorescence spectroscopy of tars revealed that the release of large aromatic systems from the steam-treated coal was only affected by the pretreatment in steam if the treatment temperature was very high (e.g. 350 degrees C). The loss of NaCl and the use of high pressure during the pretreatment of brown coal in steam were not the main reasons for the changes, in the observed tar yield. The hydrolysis of O-containing structures such as ethers, esters, and carboxylates during the pretreatment in the presence of steam plays an important role in the fates of these O-containing structures during pretreatment and subsequent pyrolysis, leading to changes in the pyrolysis behavior of the brown coal.