低变质煤热解气体产物的析出特性
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摘要
通过改变热解终温,分析气体产物成分与固体产物官能团变化关系,探究低变质煤热解过程中气体产物的析出特性。结果表明:气体产物CO在低温区主要是由于羧基、醛或酮类结构中的弱键断裂分解和小部分醚键、含氧杂环发生裂解产生的。CO_2主要是醌、醛或酮类结构和醚键结构发生裂解,以及焦油中含氧杂环或羰基官能团的断裂产生的。CH_4是由弱甲基键的断裂以及甲氧基、侧链甲基和焦油中烷烃类物质的裂解形成,固态产物与氢气发生二次反应也会产生甲烷。H_2是由极少部分游离氢自由基组合以及固态产物结构芳构化和气体分子间的聚合反应或小分子裂解产生。气体产物析出主要分四个阶段:第一阶段,煤表面吸附物质释放以及一些不稳定弱键开始断裂;第二阶段,热解程度增强,各个官能团裂解反应更为剧烈,自由基碎片大量增加;第三阶段主要是焦油发生二次裂解;第四阶段为固态产物芳构化脱氢。
Through changing the final temperature of pyrolysis,the relationship between gas product composition and solid product functional group was analyzed to explore the gas evolution characteristics of low metamorphic coal pyrolysis process.The results show that the gaseous product CO in low temperature region is mainly caused by the weak bond cleavage decomposition in the carboxyl,aldehyde or ketone structure and the cleavage of a small part of the ether bond and the oxygen-containing heterocycle.CO_2 is mainly produced by the cleavage of anthracene,aldehyde or ketone structure and ether bond structure,and the cleavage of an oxygen-containing heterocyclic or carbonyl functional group in tar.CH_4 is formed by the cleavage of a weak methyl bond,the pyrolysis of methoxy,side chain methyl and alkanes in tar,and the secondary reaction of the solid product with hydrogen.H_2 is produced by a combination of few free hydrogen radicals,aromatization of solid product structures,and polymerization of gas molecules or cleavage of small molecule.The gas product precipitation is mainly divided into four main stages.The first stage is the release of adsorbed substances on the coal surface and the cleavage of some unstable weak bonds.The second stage is the enhanced degree of pyrolysis,the cracking reaction of each functional group is more intense,and free radical fragments increase substantially.The third stage is mainly secondary cracking of tar.The fourth stage is aromatization dehydrogenation of solid products.
Through changing the final temperature of pyrolysis,the relationship between gas product composition and solid product functional group was analyzed to explore the gas evolution characteristics of low metamorphic coal pyrolysis process.The results show that the gaseous product CO in low temperature region is mainly caused by the weak bond cleavage decomposition in the carboxyl,aldehyde or ketone structure and the cleavage of a small part of the ether bond and the oxygen-containing heterocycle.CO_2 is mainly produced by the cleavage of anthracene,aldehyde or ketone structure and ether bond structure,and the cleavage of an oxygen-containing heterocyclic or carbonyl functional group in tar.CH_4 is formed by the cleavage of a weak methyl bond,the pyrolysis of methoxy,side chain methyl and alkanes in tar,and the secondary reaction of the solid product with hydrogen.H_2 is produced by a combination of few free hydrogen radicals,aromatization of solid product structures,and polymerization of gas molecules or cleavage of small molecule.The gas product precipitation is mainly divided into four main stages.The first stage is the release of adsorbed substances on the coal surface and the cleavage of some unstable weak bonds.The second stage is the enhanced degree of pyrolysis,the cracking reaction of each functional group is more intense,and free radical fragments increase substantially.The third stage is mainly secondary cracking of tar.The fourth stage is aromatization dehydrogenation of solid products.
引文
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[2]周庆凡,朱又红.从世界能源统计数据看中国能源现状[J].中国能源,2005,11:40-42.ZHOU Qingfan,ZHU Youhong.Considering Energy Situation in China Viewed from World’s Energy Statistics Data[J].Energy of China,2005,11:40-42.
[3]汪应红,郭达志,张海荣,等.我国煤炭资源势的空间分布及其应用[J].自然资源学报,2006,21(2):225-230.WANG Yinghong,GUO Dazhi,ZHANG Hairong,et al.Spatial Distribution and Applications of Coal Resource Potential in China[J].Journal of Natural Resources,2006,21(2):225-230.
[4]尚建选,王立杰,甘建平.陕北低变质煤分质综合利用前景展望[J].煤炭转化,2011,34(1):92-96.SHANG Jianxuan,WANG Lijie,GAN Jianping.Spatial Distribution and Applications of Coal Resource Potential in China[J].Coal Conversion,2011,34(1):92-96.
[5]谢克昌.能源“金三角”发展战略研究[M].北京:化学工业出版社,2016.XIE Kechang.Research on the Development Strategy of Energy“Golden Triangle”[M].Beijing:Chemical Industry Press,2016.
[6]白太宽.煤炭低温热解多联产技术---实现煤炭清洁高效利用的最佳途径[J].煤炭加工综合利用,2014(12):6-10.BAI Taikuan.Coal Low-temperature Pyrolysis Poly-generation Technology-the Best Way to Achieve Clean and Efficient Use of Coal[J].Coal Processing and Comprehensive Utilization,2014(12):6-10.
[7]吴占松,马润田,赵满成.煤炭清洁有效利用技术[M].北京:化学工业出版社,2007.WU Zhansong,MA Runtian,ZHAO Mancheng.Coal Clean and Effective Use Technology[M].Beijing:Chemical Industry Press,2007.
[8]钮志远.典型煤的官能团热解机理、动力学分析及影响因素研究[D].合肥:中国科学技术大学,2016.NIU Zhiyuan.Study on Mechanism,Kinetics of Coal Pyrolysis Based on Functional Groups and Its Impact Factors[D].Hefei:University of Science and Technology of China,2016.
[9]YAN Binhang,CHENG Yi,JIN Yong.Cross-scale Modeling and Simulation of Coal Pyrolysis to Acetylene in Hydrogen Plasma Reactors[J].AIChE Journal,2013,59(6):2119-2133.
[10]ARENILLAS A,RUBIERA F,PIS JJ,et al.Thermal Behaviour During the Pyrolysis of Low Rank Perhydrous Coals[J].Journal of Analytical and Applied Pyrolysis,2003,68/69:371-385.
[11]IGLESIAS M J,JIME’NEZ A,DEL-R’O J C,et al.Molecular Characterisation of Vitrinite in Relation to Natural Hydrogen Enrichment and Depositional Environment[J].Organic Geochemistry,2000,31:1258-1299.
[12]XU Ying,ZHANG Yongfa,WANG Yong,et al.Gas Evolution Characteristic of Lignite During Low-temperature Pyrolysis[J].Journal of Analytical and Applied Pyrolysis,2013(104):626-631.
[13]李庆钊,林柏泉,赵长遂,等.基于傅立叶红外光谱的高温煤焦表面化学结构特性分析[J].中国电机工程学报,2011,31(32):46-52.LI Qingzhao,LIN Baiquan,ZHAO Changsui,et al.Chemical Structure Analysis of Coal Char Surface Based on Fourier-transform Infrared Spectrometer[J].Proceedings of the CSEE,2011,31(32):46-52.
[14]PETERSEN H I,ROSENBERG P,NYTOFT H P.Oxygen Groups in Coals and Alginite-rich Kerogen Revisited[J].International Journal of Coal Geology,2008,74(2):93-113.