Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part II. Effects of chemical form and valence
Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part II. Effects of chemical form and valence
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DOI：
10.1016/s0016-2361(01)00128-4
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发表时间：
2002
期刊：
影响因子：
7.4
通讯作者：
D. Quyn;Hongwei Wu;S. Bhattacharya;Chun-Zhu Li
中科院分区：
文献类型：
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作者：
D. Quyn;Hongwei Wu;S. Bhattacharya;Chun-Zhu Li
通过将NaCl物理浸渍到维多利亚（Loy Yang）褐煤中来制备一组负载NaCl的煤样品。这组褐煤样品在热重分析仪和一种新型的流化床/固定床反应器中热解。后一种反应器具有流化床反应器和固定床反应器的一些特征。反应器配置允许挥发的Na被载气从炭颗粒床中扫除，避免挥发的Na在较低温度下在炭颗粒上再冷凝。同时定量了热解过程中Na和Cl的挥发。结果表明，在200°C左右，有相当比例的Cl可以挥发。从200 °C到500°C，Cl的挥发随温度的升高而急剧增加。在较高的温度和快速的加热速率，氯可以与新生的焦炭被保留在焦炭。Na的挥发遵循与Cl不同的趋势，并随着温度的升高而单调增加。NaCl的加入对褐煤的总挥发分产率和热解过程中Mg、Ca的挥发分的影响可以忽略不计。结果表明，褐煤中NaCl主要以Na和Cl的形式释放，而不是以NaCl分子的形式释放。涉及自由基的反应在钠和氯的挥发中发挥重要作用。
A set of NaCl-loaded coal samples was prepared by physically impregnating NaCl into a Victorian (Loy Yang) brown coal. This set of brown coal samples was pyrolysed in a thermogravimetric analyser and in a novel fluidised-bed/fixed-bed reactor. The latter reactor has some features of both a fluidised-bed reactor and a fixed-bed reactor. The reactor configuration allowed the volatilised Na to be swept away by carrier gas from the bed of char particles, avoiding the re-condensation of the volatilised Na on the char particles at lower temperatures. The volatilisation of Na and of Cl during pyrolysis was quantified simultaneously. The results indicated that a significant proportion of Cl could be volatilised at temperatures around 200°C. The volatilisation of Cl increased drastically with increasing temperature, from 200 to about 500°C. At higher temperatures with a fast heating rate, Cl could interact with the nascent char to be retained in the char. The volatilisation of Na followed a different trend from that of Cl and increased monotonically with increasing temperature. The loading of NaCl into the brown coal had negligible effects on the total volatile yields and on the volatilisation of Mg and Ca during pyrolysis. It is concluded that NaCl in the brown coal was mainly released as Na and Cl separately rather than as NaCl molecules. Reactions involving radicals play important roles in the volatilisation of Na and Cl.