Activation and mechanism of O<sub>2</sub> on chars from lignite steam gasification

SHEN Tian; WANG Yong-gang; LIN Xiong-chao; ZHANG Hai-yong; XU De-ping

Volume 46 Issue 11

Nov. 2018

Turn off MathJax

Article Contents

Article Navigation > Journal of Fuel Chemistry and Technology > 2018 > 46(11): 1288-1297

SHEN Tian, WANG Yong-gang, LIN Xiong-chao, ZHANG Hai-yong, XU De-ping. Activation and mechanism of O2 on chars from lignite steam gasification[J]. Journal of Fuel Chemistry and Technology, 2018, 46(11): 1288-1297.

Citation:

SHEN Tian, WANG Yong-gang, LIN Xiong-chao, ZHANG Hai-yong, XU De-ping. Activation and mechanism of O₂ on chars from lignite steam gasification[J]. Journal of Fuel Chemistry and Technology, 2018, 46(11): 1288-1297.

Citation:

PDF( 1221 KB)

Activation and mechanism of O₂ on chars from lignite steam gasification

China University of Mining and Technology(Beijing), Beijing 100083, China

Funds:

the National Key Technology Research 2012BAA04B02

More Information

Corresponding author: WANG Yong-gang, E-mail:wyg1960@126.com
Received Date: 2018-06-25
Rev Recd Date: 2018-08-25

Available Online: 2021-01-23

Publish Date: 2018-11-10

Abstract

Abstract

The char samples were prepared from pyrolysis/gasification of Shengli lignite in N₂/O₂/H₂O/H₂O+O₂ atmosphere using a one-stage novel fluidized-bed/fixed-bed quartz reactor, and characterized by BET, Raman, FT-IR, microwave digestion ICP-AES, and TGA techniques. Effects of oxygen addition on gasification reaction and the char structure and reactivity were studied to investigate the activation and mechanism of O₂ on the char. The results indicate that oxygen addition could change the char structure and improve the char reactivity, thus promoting gasification conversion and yield of H₂ and CO₂. The activation of O₂ on the char mainly includes two aspects. First, with the decomposition of aromatic nucleus by oxygen, the large π bond of aromatic rings is destroyed, and the new functional groups are generated, which could promote the reaction (C+H₂O→H₂+CO). Second, with the gasification going on, the large (≥ 6 rings) aromatic structure is depolymerized into small (3-5 rings) one, and oxygen atoms enter the aromatic nucleus, forming the defect position C-O-C. As a result, the defect degree of char microcrystalline structure increases, the polymerization degree of char microcrystalline structure decreases, and the reactivity and surface adsorption of char is improved, which could promote the reaction (CO+H₂O→H₂+CO₂).
- lignite gasification,
- char structure,
- char reactivity,
- Raman spectrum,
- fluidized-bed/fixed-bed

FullText(HTML)

References(18)

References

[1]	王永刚, 孙加亮, 张书.反应气氛对褐煤气化反应性及半焦结构的影响[J].煤炭学报, 2014, 39(8):1765-1771. http://d.old.wanfangdata.com.cn/Periodical/mtxb201408050 WANG Yong-gang, SUN Jia-liang, ZHANG Shu. Impacts of the gas atmosphere on the gasification reactivity and char structure of the brown coal[J]. J China Coal Soc, 2014, 39(8):1765-1771. http://d.old.wanfangdata.com.cn/Periodical/mtxb201408050
[2]	申恬, 王永刚, 程相龙, 林雄超.不同水蒸气浓度下褐煤气化半焦的活化及机理[J].燃料化学学报, 2017, 45(5):513-522. doi: 10.3969/j.issn.0253-2409.2017.05.001 SHEN Tian, WANG Yong-gang, CHENG Xiang-long, LIN Xiong-chao. Activation and mechanism of chars from gasification of lignite at different steam concentration[J]. J Fuel Chem Technol, 2017, 45(5):513-522. doi: 10.3969/j.issn.0253-2409.2017.05.001
[3]	LI T T, ZHANG L, DONG L, LI C-Z. Effects of gasification atmosphere and temperature on char structural evolution during the gasification of Collie sub-bituminous coal[J]. Fuel, 2014, 117(part B):1190-1195. http://www.sciencedirect.com/science/article/pii/S0016236113007680
[4]	TAY H-L, KAJITANI S, ZHANG S, LI C-Z. Effects of gasifying agent on the evolution of char structure during the gasification of Victorian brown coal[J]. Fuel, 2013, 103:22-28. doi: 10.1016/j.fuel.2011.02.044
[5]	TAY H-L, KAJITANI S, ZHANG S, LI C-Z. Inhibiting and other effects of hydrogen during gasification:Further insights from FT-Raman spectroscopy[J]. Fuel, 2014, 116:1-6. doi: 10.1016/j.fuel.2013.07.066
[6]	孙加亮, 陈绪军, 王芳, 林雄超, 王永刚.氧气对胜利褐煤水蒸气气化半焦结构及反应性的影响[J].燃料化学学报, 2015, 43(7):769-778. doi: 10.3969/j.issn.0253-2409.2015.07.001 SUN Jia-liang, CHEN Xu-jun, WANG Fang, LIN Xiong-chao, WANG Yong-gang. Effects of oxygen on the structure and reactivity of char during steam gasification of Shengli brown coal[J]. J Fuel Chem Technol, 2015, 43(7):769-778. doi: 10.3969/j.issn.0253-2409.2015.07.001
[7]	秦中宇, 王永刚, 戴瑾泽, 张雪莹, 林雄超. 10kg/h下行床褐煤低氧气化及半焦反应特性[J].煤炭转化, 2017, 40(4):23-29. doi: 10.3969/j.issn.1004-4248.2017.04.005 QIN Zhong-yu, WANG Yong-gang, DAI Jin-ze, ZHANG Xue-ying, LIN Xiong-chao. Lignite gasification and semi-coke reactivity under low-oxygen volume fraction using a 10kg/h downdraft gasifier[J]. Coal Convers, 2017, 40(4):23-29. doi: 10.3969/j.issn.1004-4248.2017.04.005
[8]	程相龙, 王永刚, 孙加亮, 申恬, 张海永, 许德平.氧化反应对胜利褐煤水蒸气气化反应的促进作用Ⅰ:宏观反应特性研究[J].燃料化学学报, 2017, 45(1):15-20. doi: 10.3969/j.issn.0253-2409.2017.01.003 CHENG Xiang-long, WANG Yong-gang, SUN Jia-liang, SHEN Tian, ZHANG Hai-yong, XU De-ping. Promoting effect of oxidation reaction on steam gasification reaction in Shengli lignite gasification process Ⅰ:Macroscopic reaction characteristic[J]. J Fuel Chem Technol, 2017, 45(1):15-20. doi: 10.3969/j.issn.0253-2409.2017.01.003
[9]	程相龙, 王永刚, 孙加亮, 申恬, 张海永, 许德平.氧化反应对胜利褐煤水蒸气气化反应的促进作用Ⅱ:作用机理研究[J].燃料化学学报, 2017, 45(2):138-146. doi: 10.3969/j.issn.0253-2409.2017.02.002 CHENG Xiang-long, WANG Yong-gang, SUN Jia-liang, SHEN Tian, ZHANG Hai-yong, XU De-ping. Promoting effect of oxidation reaction on steam gasification reaction in Shengli lignite gasification process Ⅱ:Mechanism study[J]. J Fuel Chem Technol, 2017, 45(2):138-146. doi: 10.3969/j.issn.0253-2409.2017.02.002
[10]	LI X, HAYASHI J I, LI C Z. Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part Ⅶ. Raman spectroscopic study on the changes in char structure during the catalytic gasification in air[J]. Fuel, 2006, 85(10/11):1509-1517. http://www.sciencedirect.com/science/article/pii/S0016236106000196
[11]	LI X, LI C Z. Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part Ⅷ. Catalysis and changes in char structure during gasification in steam[J]. Fuel, 2006, 85(10/11):1518-1525.
[12]	ZHANG L X, HUANG J J, FANG Y T, WANG Y. Gasification reactivity and kinetics of typical chinese anthracite chars with steam and CO₂[J]. Energy Fuels, 2006, 20(3):1201-1210. doi: 10.1021/ef050343o
[13]	YE D P, AGNEW J B, ZHANG D K. Gasification of a south australian low-rank coal with carbon dioxide and steam:Kinetics and reactivity studies[J]. Fuel, 1998, 77(11):1209-1219. doi: 10.1016/S0016-2361(98)00014-3
[14]	ZHANG S, HAYASHI J I, LI C Z. Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part Ⅸ. Effects of volatile-char interactions on char-H₂O and char-O₂ reactivities[J]. Fuel, 2011, 90(4):1655-1661. doi: 10.1016/j.fuel.2010.11.008
[15]	TAY H L, KAJITANI S, ZHANG S, LI C Z. Inhibiting and other effects of hydrogen during gasification:Further insights from FT-Raman spectroscopy[J]. Fuel, 2014, 116:1-6. doi: 10.1016/j.fuel.2013.07.066
[16]	翁诗甫.傅里叶变换红外光谱分析[M].北京:化学工业出版社, 2010. WENG Shi-fu. Fourier Transform Infrared Spectroscopy[M]. Beijing:Chemical Industry Press, 2010.
[17]	LI C-Z. Some recent advances in the understanding of the pyrolysis and gasification behaviour of Victorian brown coal[J]. Fuel, 2007, 86(12/13):1664-1683. http://www.sciencedirect.com/science/article/pii/S0016236107000361
[18]	MIN Z, YIMSIRI P, ASADULLAH M, ZHANG S, LI C Z. Catalytic reforming of tar during gasification. Part Ⅱ. Char as a catalyst or as a catalyst support for tar reforming[J]. Fuel, 2011, 90(7):2545-2552. doi: 10.1016/j.fuel.2011.03.027