The characteristics of maceral in Huangling coal and its in-situ pyrolysis
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摘要: 为了揭示煤中不同组分的热解特征和成焦规律,利用离心分离获取黄陵煤的显微组分富集物,研究显微组分的热解特性,利用显微镜热台原位观测热解过程中显微组分的软化熔融特征。结果发现,镜质组和惰质组富集物的纯度分别可达90%和80%以上,壳质组富集物的纯度接近70%。壳质组的初始热解温度在385 ℃左右,其他显微组分的初始热解温度在410 ℃左右,最大热解温度为470−480 ℃,最大失重速率和热解总失重率均以壳质组、镜质组、半镜质组和惰质组的次序降低。显微热台原位热解实验表明,壳质组(含腐泥基质)的软化温度为350−370 ℃;镜质组的软化温度为410−420 ℃,热解过程经历边缘钝化、气孔产生、表面软化、液相生成和冷却固化等阶段;半镜质组仅呈现微小的形态变化,惰质组未发生变化。黄陵煤中的活性组分为镜质组和壳质组,壳质组对共生镜质组的软化具有促进作用。Abstract: In order to reveal the pyrolysis and coking characteristics of different components in coal, the macerals in Huangling coal were enriched by centrifugation, and the pyrolysis characteristics of macerals were studied. The transformation characteristics of macerals during pyrolysis were observed in-situ by heating stage microscope. The purities of vitrinite and inertinite are more than 90% and 80%, respectively, while the purity of liptinite is nearly 70%. The initial pyrolysis temperature of liptinite is about 385 ℃, and those of the other macerals are all about 410 ℃. The maximum pyrolysis temperatures are between 470−480 ℃ for all macerals studied. The maximum weight loss rate and the total weight loss rate decrease in the order of liptinite, vitrinite, semi-vitrinite and inertinite. The softening temperature of the liptinite (including sapropelic groundmass) is 350−370 ℃, while that of vitrinite is about 410−420 ℃ as shown by the in-situ pyrolysis in a heating stage microscope. The pyrolysis process of vitrinite goes through the stages of edge shrinking, pore formation, surface softening, the formation of liquid phase, and solidification. Only slight morphological changes are observed in semi-vitrinite, while no changes are observed in inertinite. The active components in Huangling coal are vitrinite and liptinite, and the liptinite can promote the softening and melting characteristics of the adjacent vitrinite.
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Key words:
- maceral /
- in-situ pyrolysis /
- heating stage microscope /
- component separation /
- Huangling coal
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表 1 实验样品的基本煤质特征
Table 1 Basic characteristics of the coal sample
Proximate analysis/% Ultimate analysis wdaf/% Mad Ad Vdaf FCdaf C H N S $ {\rm{O}}^{*} $ 2.91 7.34 36.13 63.87 84.86 5.26 1.48 0.56 7.84 St,d/% GR.I Plastometric index/mm Audibert-Arnu dilatometer X Y t1/ ℃ t2/ ℃ t3/ ℃ a/% b/% 0.54 60 46 11 339 375 441 0.5 3.33 *by difference. X: final contraction of plastometric layer; Y: maximum thickness of plastometric layer; t1: softening temperature; t2: initial dilation temperature; t3: solidification temperature; a: maximum contraction; b: maximum dilation 表 2 黄陵煤的煤岩分析
Table 2 Petrographic composition of Huangling coal
Maceral group composition φ/% $ R^{ \circ }_{{\rm{max}}} $/% Vitrinite Semi-vitrinite Inertinite Liptinite Mineral 52.9 5.4 34.3 7.4 1.0 0.77 $ R^{ \circ }_{{\rm{max}}} $: maximum reflectance of vitrinite 表 3 显微组分富集物的分离密度及纯度
Table 3 Separation density and petrographic composition of the enriched macerals
Sample Separation density /(g·cm−3) Maceral group composition (vol, mineral free, %) Vitrinite Semi-vitrinite Inertinite Liptinite L-R < 1.260 25.7 1.5 4.8 68.0 V-R 1.300−1.320 92.7 1.0 3.2 3.1 SV-R 1.320−1.350 26.8 40.9 29.8 2.5 I-R 1.400−1.450 10.1 8.6 80.9 0.4 表 4 各显微组分富集物的煤质特征
Table 4 Characteristics of the enriched macerals
Sample Proximate analysis w/% Ultimate analysis wdaf/% St,d/% GR.I TRD Mad Ad Vdaf FCd C H N S ${\rm{O} }^{*}$ L-R 2.21 0.94 54.45 45.12 82.92 6.32 1.38 0.30 9.08 0.30 84 1.248 V-R 2.42 0.99 43.78 55.66 84.24 5.46 1.59 0.28 8.43 0.28 86 1.312 SV-R 2.51 2.48 36.02 62.39 85.12 5.02 1.47 0.30 8.09 0.29 18.8 1.324 I-R 2.62 4.26 33.24 63.92 85.98 4.80 1.32 0.37 7.53 0.35 4.6 1.427 *: by difference 表 5 纯显微组分的理论煤质特征
Table 5 Characteristics of the pure macerals
Maceral TRD Vdmmf/% Ultimate analysis wdmmf/% H/C fa C H N S ${\rm{O} }^{*}$ Liptinite 1.201 65.77 81.96 7.22 1.35 0.29 9.18 1.06 0.40 Vitrinite 1.310 43.89 84.78 5.64 1.62 0.32 7.64 0.80 0.64 Semi-Vitrinite 1.322 40.21 85.65 5.48 1.55 0.37 6.95 0.77 0.68 Inertinite 1.454 25.14 88.43 4.46 1.30 0.21 5.60 0.61 0.82 *: by difference 表 6 显微组分富集物的热解失重特征
Table 6 Characteristic parameters of pyrolysis of the enriched macerals
Parameter L-R V-R SV-R I-R ta/ ℃ 385 405 410 410 tb/ ℃ 472 472 478 480 tc/ ℃ 513 530 540 540 Maximum decomposition rate/(%·min−1) 10.80 9.10 5.65 4.32 -
[1] 杨桃, 刘犇, 宋燕, 马兆昆, 宋怀河, 刘占军. 高温煤沥青中间相热转化行为[J]. 新型炭材料,2019,34(6):546−551.YANG Tao, LIU Ben, SONG Yan, MA Zhao-kun, SONG Huai-he, LIU Zhan-jun. Formation and transformation behavior of mesophase from three high softening-point pitches[J]. New Carbon Mater,2019,34(6):546−551. [2] NAMKUNG H, HU X, KIM H, WANG F, YU G. Evaluation of sintering behavior of ash particles from coal and rice straw using optical heating stage microscope at high temperature fouling conditions[J]. Fuel Process Technol,2016,149:195−208. doi: 10.1016/j.fuproc.2016.04.020 [3] XU J, ZHAO F, GUO Q, YU G, LIU X, WANG F. Characterization of the melting behavior of high-temperature and low-temperature ashes[J]. Fuel Process Technol,2015,134:441−448. doi: 10.1016/j.fuproc.2014.12.054 [4] LIU M, BAI J, KONG L, BAI Z, HE C, LI W. The correlation between coal char structure and reactivity at rapid heating condition in TGA and heating stage microscope[J]. Fuel,2020,260:116318. doi: 10.1016/j.fuel.2019.116318 [5] 张林民, 王焦飞, 白永辉, 苏暐光, 宋旭东, 于广锁. 宁东煤灰层/熔渣界面煤焦气化反应特性原位研究[J]. 燃料化学学报,2020,48(2):129−136. doi: 10.3969/j.issn.0253-2409.2020.02.001ZHANG Lin-min, WANG Jiao-fei, BAI Yong-hui, SU Wei-guang, SONG Xu-dong, YU Guang-suo. In-situ study of Ningdong char particles gasification characteristics on the interface of ash layer and slag[J]. J Fuel Chem Technol,2020,48(2):129−136. doi: 10.3969/j.issn.0253-2409.2020.02.001 [6] 张新沙, 宋旭东, 苏暐光, 卫俊涛, 白永辉, 于广锁. 宁东煤煤焦-CO2气化反应特性的原位研究[J]. 燃料化学学报,2019,47(4):385−392. doi: 10.1016/S1872-5813(19)30018-0ZHANG Xin-sha, SONG Xu-dong, SU Wei-guang, WEI Jun-tao, BAI Yong-hui, YU Guang-suo. In-situ study on gasification reaction characteristics of Ningdong coal chars with CO2[J]. J Fuel Chem Technol,2019,47(4):385−392. doi: 10.1016/S1872-5813(19)30018-0 [7] 常海洲, 曾凡桂, 李文英, 李美芬, 李军, 谢克昌. 煤及其显微组分热解过程中的半焦收缩动力学[J]. 物理化学学报,2008,24(4):675−680. doi: 10.3866/PKU.WHXB20080422CHANG Hai-zhou, ZENG Fan-gui, LI Wen-ying, LI Mei-fen, LI Jun, XIE Ke-chang. Semicoke contraction kinetics of coal and its macerals in pyrolysis[J]. Acta Phys-chim Sin,2008,24(4):675−680. doi: 10.3866/PKU.WHXB20080422 [8] 张永发, 张慧荣, 田芳, 孙亚玲. 无烟粉煤成型块炭化行为及热解气体生成规律[J]. 煤炭学报,2011,36(4):670−675.ZHANG Yong-fa, ZHANG Hui-rong, TIAN Fang, SUN Ya-ling. The characteristics of anthracite briquette carbonization and the regularity of pyrolysis gas generation during carbonization[J]. J China Coal Soc,2011,36(4):670−675. [9] 姚海. 流化床中煤颗粒热膨胀破碎特性的实验研究与定量评价[D]. 武汉: 华中科技大学, 2006.YAO Hai. experimental study and quantitative estimate on thermal expansion and fragmentation characteristics of coal particle in fluidized bed[D]. Wuhan: Huazhong University of Science & Technology, 2006. [10] 沈寓韬, 张卫华, 鲁锡兰, 田英奇, 张德祥. 不同炼焦煤显微组分特点及其对结焦性能的影响[J]. 煤炭技术,2016,35(10):316−318.SHEN Yu-tao, ZHANG Wei-hua, LU Xi-lan, TIAN Ying-qi, ZHANG De-xiang. Characterization of coking coal maceral and its relationship to coking properties[J]. Coal Technol,2016,35(10):316−318. [11] 罗俊文, 叶道敏, 黄海智, 肖文钊. 西南地区某些煤中镜质体的加热特征[J]. 煤田地质与勘探,1994,22(6):22−25.LUO Jun-wen, YE Dao-min, HUANG Hai-zhi, XIAO Wen-zhao. Heating characteristics of vitrinite in some coals in southwest China[J]. Coal Geol Explor,1994,22(6):22−25. [12] 孙翊博, 王绍清, 舒昆昆, 苏珅, 马薇, 邵瑞. 树皮煤受热物理变化特征研究[J]. 中国煤炭,2017,43(3):93−98. doi: 10.3969/j.issn.1006-530X.2017.03.020SUN Yi-bo, WANG Shao-qing, SHU Kun-kun, SU Shen, MA Wei, SHAO Rui. The changes of physical characteristics of bark coal when heating[J]. China Coal,2017,43(3):93−98. doi: 10.3969/j.issn.1006-530X.2017.03.020 [13] 王越, 丁华, 武琳琳, 张宇宏, 白向飞, 曲思建. 低温热转化过程中煤中典型壳质组的荧光和Micro-FTIR特征[J]. 燃料化学学报,2021,49(5):598−608.WANG Yue, DING Hua, WU Lin-lin, ZHANG Yu-hong, BAI Xiang-fei, QU Si-jian. The fluorescence and Micro-FTIR characteristics of typical liptinite in low temperature thermal conversion[J]. J Fuel Chem Technol,2021,49(5):598−608. [14] 刘涛. 不同变质程度煤的热解特性及其共炭化研究[D]. 合肥: 安徽工业大学, 2013.LIU Tao. Study on the pyrolysis and Co-carbonization performance of different rank of coal[D]. Hefei: Anhui University of Technology, 2013. [15] 康西栋, 胡善亭, 潘治贵, 潘银苗, 王凌志. 华北地区煤的显微组分结焦性热台试验[J]. 地球科学—中国地质大学学报,1997,22(2):181−184.KANG Xi-dong, HU Shan-ting, PAN Zhi-gui, PAN Yin-miao, WANG Ling-zhi. Heating stage test on the coking properties of macerals of coal[J]. Earth Sci,1997,22(2):181−184. [16] 白向飞, 张宇宏. 中国炼焦商品煤质量现状分析[J]. 煤质技术,2013,28(1):1−3. doi: 10.3969/j.issn.1007-7677.2013.01.001BAI Xiang-fei, ZHANG Yu-hong. Analysis on the quality of Chinese commercial coking coals[J]. Coal Qual Technol,2013,28(1):1−3. doi: 10.3969/j.issn.1007-7677.2013.01.001 [17] 白向飞, 李文华, 陈文敏, 马伟伟. 我国西部弱还原程度煤分布及煤质特征研究[J]. 煤炭学报,2005,30(4):502−506. doi: 10.3321/j.issn:0253-9993.2005.04.022BAI Xiang-fei, LI Wen-hua, CHEN Wen-min, MA Wei-wei. Study on distribution and characteristics of coals with weak reductive degree in west China[J]. J China Coal Soc,2005,30(4):502−506. doi: 10.3321/j.issn:0253-9993.2005.04.022 [18] 白向飞, 李文华, 罗陨飞, 陈洪博. 中国西部弱还原性煤的结构特征初步研究[J]. 煤炭转化,2006,29(4):5−8. doi: 10.3969/j.issn.1004-4248.2006.04.002BAI Xiang-fei, LI Wen-hua, LUO Yun-fei, CHEN Hong-bo. Preliminary study on structural characteristics of coal with weak reductivity in west China[J]. Coal Convers,2006,29(4):5−8. doi: 10.3969/j.issn.1004-4248.2006.04.002 [19] 韩德馨. 中国煤岩学[M]. 徐州: 中国矿业大学出版社, 1996: 196.HAN De-xin. China Coal Petrology[M]. Xuzhou: China University of Mining and Technology Press, 1996: 196. [20] 谢克昌. 煤的结构与反应性[M]. 北京: 科学出版社, 2002: 252−262.XIE Ke-chang. Coal Structure and Its Reactivity[M]. Beijing: Science Press, 2002: 252−262. [21] 罗陨飞. 煤的大分子结构研究-煤中惰质组结构及煤中氧的赋存形态[D]. 北京: 煤炭科学研究总院, 2002.LUO Yun-fei. Study on macromolecular structure of coal-inertinite structure and occurrence of oxygen in coal[D]. Beijing: China Coal Research Institute, 2002. [22] DAI S, BECHTEL A, EBLE C F, FLORES R M, FRENCH D, GRAHAM I T, HOOD M M, HOWER J C, KORASIDIS V A, MOORE T A, PÜTTMANN W, WEI Q, ZHAO L, O'KEEFE J M K. Recognition of peat depositional environments in coal: A review[J]. Int J Coal Geol,2020,219:103383. doi: 10.1016/j.coal.2019.103383 [23] 陈鹏. 中国煤炭性质、分类和利用[M]. 北京: 化学工业出版社, 2007: 33−35.CHEN Peng. Nature, Classification and Utilization of Coal in China[M]. Beijing: Chemical Industry Press, 2007: 33−35. [24] 斯塔赫. 斯塔赫煤岩学教程[M]. 北京: 煤炭工业出版社, 1990: 184−201.STACH E. Stach’s Textbook of Coal Petrology[M]. Beijing: Coal Industry Press, 1990: 184−201. [25] TAYLOR G H, TEICHMÜLLER M, DAVIS A, DIESSEL C F K, LITTKE R, ROBERT P. The Organic Petrology[M]. Berlin: Gebruder Borntraeger, 1998: 35−39. [26] SUAREZ-RUIZ I, CRELLING J C. Applied Coal Petrology: The Role of Petrology in Coal Utilization[M]. Amsterdam: Elsevier Science Ltd, 2008: 44−48. [27] 叶道敏, 肖文钊, 罗俊文, 黄海智. 煤岩学配煤和焦炭强度预测的研究[J]. 煤田地质与勘探,1998,26(S1):5−8.YE Dao-min, XIAO Wen-zhao, LUO Jun-wen, HUANG Hai-zhi. Study on blending and coke strength prediction using coal petrology[J]. Coal Geol Explor,1998,26(S1):5−8. [28] 周师庸, 赵俊国. 炼焦煤性质与高炉焦炭质量[M]. 北京: 冶金工业出版社, 2005: 1−8.ZHOU Shi-yong, ZHAO Jun-guo. Properties of Coking Coal and Coke Quality of Blast Furnace[M]. Beijing: Metallurgical Industry Press, 2005: 36−55.