Microwave-assisted and analytical pyrolysis of coking and non-coking coals: Comparison of tar and char compositions
Microwave-assisted and analytical pyrolysis of coking and non-coking coals: Comparison of tar and char compositions
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DOI：
10.1016/j.jaap.2019.05.003
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发表时间：
2019-09
影响因子：
6
通讯作者：
B. R. Reddy;B. Shravani;Bidyut Das;P. S. Dash;R. Vinu
中科院分区：
文献类型：
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作者：
B. R. Reddy;B. Shravani;Bidyut Das;P. S. Dash;R. Vinu
热解条件和热解机理对煤焦油的质量有很大的影响，并最终决定了煤焦油的进一步利用。本文研究了三种炼焦煤和一种非炼焦高灰印度煤通过微波辅助和常规加热的热解，以及加热速率、煤种和加热机理对产物产率和焦油组成的影响。在自制的微波反应器中进行微波热解实验，并且在与气相色谱-质谱仪（Py-GC/MS）连接的Pyroprobe®中进行分析热解实验。炼焦煤微波热解的焦油产率相似（约7 wt.%），而来自高灰分印度煤（约11wt%）的则稍高。来自微波热解和分析热解的炭产率相似（78 ± 1.5wt.%）。微波热解焦油富含萘衍生物和多环芳烃，选择性大于45%，而分析热解焦油富含单环芳烃（>30%）。其他有机组分的选择性没有显着变化。微波热解焦油中多环芳烃的高选择性是由于局部热点的产生，导致初级热解蒸汽的过度裂解。微波热解焦油的较高热值（HHV）为32-33 MJ kg−1，而分析热解焦油的较高热值（35-36 MJ kg−1），这归因于后者中存在更多的单芳烃。氢气和甲烷是气体馏分中的主要组分。使用不同的技术表征煤焦，并且它们富含碳（约80重量%）。能量含量高（29 MJ kg−1）。
Pyrolysis conditions and mechanism greatly influence the quality of tar and char from coal, which eventually determine their further usage. This work investigates the pyrolysis of three coking coals and a non-coking high ash Indian coal via microwave-assisted and conventional heating, and the influence of heating rate, coal type, and heating mechanism on product yields and tar composition. Microwave pyrolysis experiments were conducted in a home-built microwave reactor, and analytical pyrolysis experiments were conducted in a Pyroprobe®interfaced with gas chromatograph-mass spectrometer (Py-GC/MS). The tar yields from microwave pyrolysis of coking coals were similar (∼7 wt.%), while it was slightly high from high ash Indian coal (∼11 wt.%). Char yields from both microwave and analytical pyrolysis were similar (78 ± 1.5 wt.%). Microwave pyrolysis tars were rich in naphthalene derivatives and polyaromatics with more than 45% selectivity, while analytical pyrolysis tar was rich in monoaromatics (>30%). There was no significant variation in the selectivities of other organic fractions. High selectivity of polyaromatics in microwave pyrolysis tar is due to the generation of localized hotspots, which led to excessive cracking of primary pyrolysis vapors. The higher heating value (HHV) of microwave pyrolysis tar was 32–33 MJ kg−1, while that of analytical pyrolysis tar was higher (35–36 MJ kg−1), which is attributed to the presence of more monoaromatics in the latter. Hydrogen and methane were the major components in the gaseous fraction. Coal chars were characterized using different techniques, and they were rich in carbon (≈80 wt.%) with high energy content (29 MJ kg−1).