矿物质对高碱煤显微组分热解特性的影响
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摘要
利用固定床热解炉和热重分析仪研究了沙尔湖煤显微组分的热解特性和产物产率,考察了酸洗处理对热解产物和动力学参数的影响。结果表明:经浮沉实验发现镜质组富集于S2(密度为1.4～1.5g/cm3浮选煤样)中,惰质组富集于S3(密度为>1.5g/cm3浮选煤样)中,其中S3所含硅铝酸盐类矿物显著高于S2。且碱及碱土金属(alkali and alkaline earth metals, AAEM)多以可溶性形式存在,经酸洗处理后剩余矿物质主要为石英、高岭土及硅酸盐类。在选用不同煤样进行热解特性分析发现,碱及碱土金属的存在会抑制热解主反应阶段的挥发分释放,而在二次脱气阶段,AAEM矿物质则会提高挥发分的释放速率。且在热解实验中发现,AAEM在热解中会充当煤大分子结构的交联点,降低热解焦油产率。对比不同显微组分发现,惰质组热稳定性更强,镜质组中烷烃侧链较多,芳香度较小,更易受热断裂。采用Doyle积分法确定了沙尔湖煤热解反应的动力学参数。
The fixed bed furnace and thermogravimetric analyzer were used to investigate the pyrolysis characteristics and products distribution of maceral in Shaerhu coal. Furthermore, the influence of acid washing treatment on pyrolysis products and kinetics of Shaerhu coal was also discussed. The vitrinite was enriched in S2(the densities ranging from 1.4—1.5 g/cm3) and the inertinite was enriched in S3(the densities ranging from >1.5 g/cm3) with the floatation experiments. The content of silicate minerals in S3 was more than that in S2. And AAEM(alkali and alkaline earth metals) was existed in soluble form. The results showed that the acid washing of coal could remove most of the minerals, and the residual minerals were mainly quartz, kaolinite and silicate. The release rate of volatiles during the pyrolysis stage was inhibited, while during the secondary degassing stage it was raised in the presence of alkali and alkaline earth metals(AAEM). The release rate of volatiles during the main pyrolysis stage and final weight loss reduced. In this case, the decreasing yield of tar lied in the fact that AAEM was regarded as the crosslinking point for coal macromolecules in pyrolysis. Compared with different macerals, the thermal stability of inertinite group was stronger. The vitrinite group had more alkane side chains, less aromaticity and more susceptible to thermal fracture. The kinetic parameters of coal pyrolysis were obtained by the processing method with Doyle integration.
The fixed bed furnace and thermogravimetric analyzer were used to investigate the pyrolysis characteristics and products distribution of maceral in Shaerhu coal. Furthermore, the influence of acid washing treatment on pyrolysis products and kinetics of Shaerhu coal was also discussed. The vitrinite was enriched in S2(the densities ranging from 1.4—1.5 g/cm3) and the inertinite was enriched in S3(the densities ranging from >1.5 g/cm3) with the floatation experiments. The content of silicate minerals in S3 was more than that in S2. And AAEM(alkali and alkaline earth metals) was existed in soluble form. The results showed that the acid washing of coal could remove most of the minerals, and the residual minerals were mainly quartz, kaolinite and silicate. The release rate of volatiles during the pyrolysis stage was inhibited, while during the secondary degassing stage it was raised in the presence of alkali and alkaline earth metals(AAEM). The release rate of volatiles during the main pyrolysis stage and final weight loss reduced. In this case, the decreasing yield of tar lied in the fact that AAEM was regarded as the crosslinking point for coal macromolecules in pyrolysis. Compared with different macerals, the thermal stability of inertinite group was stronger. The vitrinite group had more alkane side chains, less aromaticity and more susceptible to thermal fracture. The kinetic parameters of coal pyrolysis were obtained by the processing method with Doyle integration.
引文
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[15]梁虎珍,曾凡桂,李美芬,等.镧系收缩效应对稀土-煤相互作用的影响及煤中有机态稀土的赋存形式研究[J].燃料化学学报, 2013,41(9):1030-1040.LIANG Huzhen, ZENG Fangui, LI Meifen, et al. Influence of lanthanide contraction effect on the interaction of REE and coal and the occurrence forms of organic rare earth element in coals[J]. Journal of Fuel Chemistry and Technology, 2013, 41(9):1030-1040.
[16]陈艳巨,周剑林,王永刚,等.水热处理对褐煤含氧官能团和亲水性的影响[J].煤炭转化, 2014, 37(3):27-32.CHEN Yanju, ZHOU Jianlin, WANG Yonggang, et al. Effects of hydrothermal treatment on O-containing functional groups removal and hydrophilic property of Shengli lignite[J]. Coal Conversion, 2014,37(3):27-32.
[17] ORHAN G, IBRAHIM D, AYDIN D, et al. Subtractive-FTIR spectroscopy to characterize organic matter in lignite samples from different depths[J]. Spectrochimica Acta(Part A), 2012, 96:63-69.
[18] XU Xiuqiang, WANG Yonggang, CHEN Zongding, et al. Influence of cooling treatments on char microstructure and reactivity of Shengli brown coal[J]. Journal of Fuel Chemistry and Technology, 2015, 43(1):1-8.
[19] LARSEN J W, PAN C S, SHAWVER S. Effect of demineralization on the macromolecular structure of coals[J]. Energy Fuels, 1989, 3(5):557-561.
[20]张军,袁建伟,徐益谦.矿物质对煤粉热解的影响[J].燃烧科学与技术, 1998(1):66-71.ZHANG Jun, YUAN Jianwei, XU Yiqian. Effects of mineral matter on pyrolysis of pulverized coal[J]. Journal of Combustion Science and Technology, 1998(1):66-71.
[21]谢克昌.煤的结构与反应性[M].北京:科学出版社, 2002.XIE Kechang. Structure and reactivity of coal[M]. Beijing:Science Press, 2002.
[22]邱朋华,赵岩,陈希叶,等.碱及碱土金属对准东煤热解特性及动力学影响分析[J].燃料化学学报, 2014, 42(10):1178-1189.QIU Penghua, ZHAO Yan, CHEN Xiye, et al. Effects of alkali and alkaline earth metallic species on pyrolysis characteristics and kinetics of Zhundong coal[J]. Journal of Fuel Chemistry and Technology, 2014,42(10):1178-1189.
[23] XU Shengqi, ZHOU Zhijie, XIONG Jie, et al. Effects of alkaline metal on coal gasification at pyrolysis and gasification phases[J]. Fuel, 2011,90(5):1723-1730.
[24]许慎启,周志杰,代正华,等.碱金属及灰分对煤焦碳微晶结构及气化反应特性的影响[J].高校化学工程学报, 2010, 24(1):64-70.XU Shenqi, ZHOU Zhijie, DAI Zhenghua, et al. Effects of alkalimetal and ash on crystallite structure of coal char during pyrolysis and on gasification reactivity[J]. Journal of Chemical Engineering of Chinese Universities, 2010, 24(1):64-70.
[25]朱学栋,朱子彬,朱学余,等.煤化程度和升温速率对煤热分解影响的研究[J].煤炭转化, 1999, 22(2):43-47.ZHU Xuedong, ZHU Zibin, ZHU Xueyu, et al. Study on the effect of coal rank and heating rate on the pyrolysis[J]. Coal Conversion, 1999,22(2):43-47.
[26] LI Chunzhu, SATHE C, KERSHAW J R, et al. Fates and roles of alkali and alkaline earth metals during the pyrolysis of a Victorian brown coal[J]. Fuel, 2000, 79(3):427-438.
[27] HIRSCHFELDER J O. Semi-empirical calculations of activation energies[J]. The Journal of Chemical Physics, 1941, 9(8):645-654.
[28]李军,冯杰,李文英.神府东胜煤镜质组和惰质组的热化学反应差异[J].物理化学学报, 2009, 25(7):1311-1319.LI Jun, FENG Jie, LI Wenying. Thermochemical reaction representation of Shenfu Dongshen inertinite and vitrinite[J]. Acta Physico-Chimica Sinica, 2009, 25(7):1311-1319.
[2] GE Huijun, SHEN Laihong, GU Haiming, et al. Combustion performance and sodium transformation of high-sodium Zhundong coal during chemical looping combustion with hematite as oxygen carrier[J].Fuel, 2015, 159:107-117.
[3] LI Xiao, BAI Zongqing, BAI Jin, et al. Insight into the effects of sodium species with different occurrence modes on the structural features of residues derived from direct liquefaction of Zhundong coal by multiple techniques[J]. Energy Fuel, 2015, 29(11):7142-7149.
[4] ZHOU Bin, ZHOU Hao, WANG Jianyang, et al. Effect of temperature on the sintering behavior of Zhundong coal ash in oxy-fuel combustion atmosphere[J]. Fuel, 2015, 150:526-537.
[5]裴贤丰.低阶煤热转化产品特性影响因素研究及展望[J].洁净煤技术, 2016, 22(1):33-37.PEI Xianfeng. Research and development of thermal conversion characteristics for low rank coal[J]. Clean Coal Technology, 2016, 22(1):33-37.
[6] TIAN Bin, QIAO Yingyun, TIAN Yuanyu, et al. Investigation on the effect of particle size and heating rate on pyrolysis characteristics of a bituminous coal by TG-FTIR[J]. Journal of Analytical and Applied Pyrolysis, 2016, 121:376-386.
[7] XU Xiuqiang, WANG Yonggang, CHEN Zongding, et al. Variations in char structure and reactivity due to the pyrolysis and in-situ gasification using Shengli brown coal[J]. Journal of Analytical and Applied Pyrolysis, 2015, 115:233-241.
[8]赵伟,张晓欠,周安宁,等.神府煤煤岩显微组分的浮选分离及富集物的低温热解产物特性研究[J].燃料化学学报, 2014, 42(5):527-533.ZHAO Wei, ZHANG Xiaoqian, ZHOU Anning, et al. Flotation separation of Shenfu coal macerals and low temperature pyrolysis characteristics of different maceral concentrate[J]. Journal of Fuel Chemistry and Technology, 2014, 42(5):527-533.
[9] ZHAO Yunpeng, HU Haoquan, JIN Lijun, et al. Pyrolysis behavior of vitrinite and inertinite from Chinese Pingshuo coal by TG-MS and in a fixed bed reactor[J]. Fuel Processing Technology, 2011, 92:780-786.
[10] SATHE C, HAYASHI J I, LI Chunzhu, et al. Release of alkali and alkaline earth metallic species during rapid pyrolysis of a Victorian brown coal at elevated pressures[J]. Fuel, 2003, 82(12):1491-1497.
[11] HAYASHI J I, MORI T, AMAMOTO S, et al. Flash pyrolysis of brown coal modified by alcohol-vapor explosion treatment[J]. Energy Fuels,1996, 10(5):1099-1107.
[12]江国栋,魏利平,滕海鹏,等.基于热重法的准东煤等转化率热解动力学模型[J].化工学报, 2017, 68(4):1415-1422.JIANG Guodong, WEI Liping, TENG Haipeng, et al. A kinetic model based on TGA data for pyrolysis of Zhundong coal[J]. CIESC Journal,2017, 68(4):1415-1422.
[13]谢昌亚,王云刚,赵钦新,等.准东煤热解特性及气化活性实验研究[J].中国电机工程学报, 2016, 36(s1):95-102.XIE Changya, WANG Yungang, ZHAO Qinxin, et al. Experimental study on Zhundong coal’s pyrolysis characteristics and gasification activity[J]. Proceedings of the CSEE, 2016, 36(s1):95-102.
[14]朱川,曲思建,张凝凝,等.新疆白石湖富镜质组高碱煤热解特性[J].煤炭学报, 2017, 42(10):2725-2732.ZHU Chuan, QU Sijian, ZHANG Ningning, et al. Pyrolysis characteristics of Xinjiang Baishihu vitrinite-rich coal with high alkali content[J]. Journal of China Coal Society, 2017, 42(10):2725-2732.
[15]梁虎珍,曾凡桂,李美芬,等.镧系收缩效应对稀土-煤相互作用的影响及煤中有机态稀土的赋存形式研究[J].燃料化学学报, 2013,41(9):1030-1040.LIANG Huzhen, ZENG Fangui, LI Meifen, et al. Influence of lanthanide contraction effect on the interaction of REE and coal and the occurrence forms of organic rare earth element in coals[J]. Journal of Fuel Chemistry and Technology, 2013, 41(9):1030-1040.
[16]陈艳巨,周剑林,王永刚,等.水热处理对褐煤含氧官能团和亲水性的影响[J].煤炭转化, 2014, 37(3):27-32.CHEN Yanju, ZHOU Jianlin, WANG Yonggang, et al. Effects of hydrothermal treatment on O-containing functional groups removal and hydrophilic property of Shengli lignite[J]. Coal Conversion, 2014,37(3):27-32.
[17] ORHAN G, IBRAHIM D, AYDIN D, et al. Subtractive-FTIR spectroscopy to characterize organic matter in lignite samples from different depths[J]. Spectrochimica Acta(Part A), 2012, 96:63-69.
[18] XU Xiuqiang, WANG Yonggang, CHEN Zongding, et al. Influence of cooling treatments on char microstructure and reactivity of Shengli brown coal[J]. Journal of Fuel Chemistry and Technology, 2015, 43(1):1-8.
[19] LARSEN J W, PAN C S, SHAWVER S. Effect of demineralization on the macromolecular structure of coals[J]. Energy Fuels, 1989, 3(5):557-561.
[20]张军,袁建伟,徐益谦.矿物质对煤粉热解的影响[J].燃烧科学与技术, 1998(1):66-71.ZHANG Jun, YUAN Jianwei, XU Yiqian. Effects of mineral matter on pyrolysis of pulverized coal[J]. Journal of Combustion Science and Technology, 1998(1):66-71.
[21]谢克昌.煤的结构与反应性[M].北京:科学出版社, 2002.XIE Kechang. Structure and reactivity of coal[M]. Beijing:Science Press, 2002.
[22]邱朋华,赵岩,陈希叶,等.碱及碱土金属对准东煤热解特性及动力学影响分析[J].燃料化学学报, 2014, 42(10):1178-1189.QIU Penghua, ZHAO Yan, CHEN Xiye, et al. Effects of alkali and alkaline earth metallic species on pyrolysis characteristics and kinetics of Zhundong coal[J]. Journal of Fuel Chemistry and Technology, 2014,42(10):1178-1189.
[23] XU Shengqi, ZHOU Zhijie, XIONG Jie, et al. Effects of alkaline metal on coal gasification at pyrolysis and gasification phases[J]. Fuel, 2011,90(5):1723-1730.
[24]许慎启,周志杰,代正华,等.碱金属及灰分对煤焦碳微晶结构及气化反应特性的影响[J].高校化学工程学报, 2010, 24(1):64-70.XU Shenqi, ZHOU Zhijie, DAI Zhenghua, et al. Effects of alkalimetal and ash on crystallite structure of coal char during pyrolysis and on gasification reactivity[J]. Journal of Chemical Engineering of Chinese Universities, 2010, 24(1):64-70.
[25]朱学栋,朱子彬,朱学余,等.煤化程度和升温速率对煤热分解影响的研究[J].煤炭转化, 1999, 22(2):43-47.ZHU Xuedong, ZHU Zibin, ZHU Xueyu, et al. Study on the effect of coal rank and heating rate on the pyrolysis[J]. Coal Conversion, 1999,22(2):43-47.
[26] LI Chunzhu, SATHE C, KERSHAW J R, et al. Fates and roles of alkali and alkaline earth metals during the pyrolysis of a Victorian brown coal[J]. Fuel, 2000, 79(3):427-438.
[27] HIRSCHFELDER J O. Semi-empirical calculations of activation energies[J]. The Journal of Chemical Physics, 1941, 9(8):645-654.
[28]李军,冯杰,李文英.神府东胜煤镜质组和惰质组的热化学反应差异[J].物理化学学报, 2009, 25(7):1311-1319.LI Jun, FENG Jie, LI Wenying. Thermochemical reaction representation of Shenfu Dongshen inertinite and vitrinite[J]. Acta Physico-Chimica Sinica, 2009, 25(7):1311-1319.