[BMIM][BF_4]对不同变质程度煤自燃热行为的影响研究
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摘要
离子液体作为新型阻化剂可溶解破坏煤中活性基团,抑制煤氧化反应进程,从根本上达到阻化煤自燃的目的。但不同变质程度煤样微观结构不同,而且离子液体成本较高,因此,难以在煤自燃领域现场实施应用。基于此,考察了离子液体对不同变质程度煤自燃热行为特征的影响,且从经济性和实用性方面考虑,选用低浓度(质量分数为5%) 1-丁基-3-甲基咪唑四氟硼酸盐([BMIM][BF4])对褐煤、长焰煤、气煤以及1/3焦煤进行热重-差热联用(TG-DSC)实验和热物性参数测试实验,得出离子液体处理不同变质程度煤的特征温度、热效应及热物性参数变化规律。结果表明:离子液体延后了煤失重过程中的特征温度,提高了煤自燃过程中的初始放热温度和最大热释放速率温度,对最大放热速率以及放热量都有着明显的抑制效应,且抑制作用随着煤变质程度的升高而减弱,说明离子液体对于低阶煤效果较好;与原煤样相比,离子液体处理煤样的热扩散系数和导热系数较低,比热容则较高,说明离子液体降低了煤体之间热量传递的速度,增加了煤体温度上升所需的热量,弱化了煤体因温差传递热量的能力,对煤样的传热性能起到了抑制作用,并且煤的变质程度越低,抑制效果越明显。结果可为离子液体抑制煤自燃领域的推广及现场应用提供借鉴。
Ionic liquid(IL) is a new type inhibitor,which can inhibit the active functional groups in the molecular structure in coal,and inhibit coal oxidation process.However,different metamorphic coal samples have different microstructures.Moreover,IL has high cost,which is difficult to implement in the field of coal spontaneous combus-tion(CSC).To investigate the effects of IL on the thermal properties of CSC with different metamorphic levels,consid-eringeconomics and practicality,low concentration(5 mass%) 1-butyl-3-methylazole tetrafluoroborate([BMIM][BF4])is used to treat coal samples.Using simultaneous thermal analysis(STA) and laser flash apparatus(LFA),the oxidation and exothermic behaviors of four types of coal were analyzed. The characteristic temperature,thermal effects and thermophysical parameters of coal with different metamorphic levels of IL treatment were obtained. The results show that the [BMIM][BF4]delayed the characteristic temperature of coal mass loss,increased the initial/maximum heat release temperature,and reduced the maximum heat release rate/thermal release during CSC.Moreover,the inhibition effect decreases as the levels of coal metamorphism increases.Compared with the raw coal sample,the thermal diffusion coefficient and thermal conductivity of the treated coal sample are lower,and the specific heat capacity is higher.Namely,the [BMIM][BF4]reduces the rate of heat transfer between coal bodies and weakens the ability to transfer heat due to temperature difference,increases the heat required to raise the temperature of the coal bodies.In addition,the lower the levels of coal metamorphism,the more significant the inhibiting impact on CSC.The study results provide a theoretical basis for the promotion and application of IL inhibit at CSC field.
Ionic liquid(IL) is a new type inhibitor,which can inhibit the active functional groups in the molecular structure in coal,and inhibit coal oxidation process.However,different metamorphic coal samples have different microstructures.Moreover,IL has high cost,which is difficult to implement in the field of coal spontaneous combus-tion(CSC).To investigate the effects of IL on the thermal properties of CSC with different metamorphic levels,consid-eringeconomics and practicality,low concentration(5 mass%) 1-butyl-3-methylazole tetrafluoroborate([BMIM][BF4])is used to treat coal samples.Using simultaneous thermal analysis(STA) and laser flash apparatus(LFA),the oxidation and exothermic behaviors of four types of coal were analyzed. The characteristic temperature,thermal effects and thermophysical parameters of coal with different metamorphic levels of IL treatment were obtained. The results show that the [BMIM][BF4]delayed the characteristic temperature of coal mass loss,increased the initial/maximum heat release temperature,and reduced the maximum heat release rate/thermal release during CSC.Moreover,the inhibition effect decreases as the levels of coal metamorphism increases.Compared with the raw coal sample,the thermal diffusion coefficient and thermal conductivity of the treated coal sample are lower,and the specific heat capacity is higher.Namely,the [BMIM][BF4]reduces the rate of heat transfer between coal bodies and weakens the ability to transfer heat due to temperature difference,increases the heat required to raise the temperature of the coal bodies.In addition,the lower the levels of coal metamorphism,the more significant the inhibiting impact on CSC.The study results provide a theoretical basis for the promotion and application of IL inhibit at CSC field.
引文
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[11] ZHANG Weiqing,JIANG Shuguang,WU Zhengyan,et al.Influence of imidazolium-based ionic liquids on coal oxidation[J]. Fuel,2018,217:529-535.
[12] ZHANG Weiqing,JIANG Shuguang,HARDACRE Christopher,et al.Inhibitory effect of phosphonium-based ionic liquids on coal oxidation[J].Energy&Fuels,2014,28(7):4333-4341.
[13] ZHANG Weiqing,JIANG Shuguang,WANG Kai,et al.An experimental study of the effect of ionic liquids on the low temperature oxidation of coal[J]. International Journal of Mining Science and Technology,2012,22(5):687-691.
[14] XIAO Yang,LHuifei,YI Xin,et al.Treating bituminous coal with ionic liquids to inhibit coal spontaneous combustion[J]. Journal of Thermal Analysis&Calorimetry,2018. https://doi. org/10. 1007/s10973-018-7600-5.
[15] CUI Fusheng,BIN Laiwang,SHU Chimin,et al.Inhibiting effect of imidazolium-based ionic liquids on the spontaneous combustion characteristics of lignite[J].Fuel,2018,217:508-514.
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[17]邓军,陈炜乐,肖旸,等.咪唑类离子液体对煤热物性参数影响的实验研究[J].西安科技大学学报,2018,38(4):523-529.DENG Jun,CHEN Weile,XIAO Yang,et al.Experimental study on influence of imidazolium-based ionic liquids on thermo-physical parameters of coal[J]. Journal of Xi’an University of Science and Technology,2018,38(4):523-529.
[18]张卫清.咪唑类和季膦盐类室温离子液体影响煤氧化特性的基础研究[D].徐州:中国矿业大学,2013.ZHANG Weiqing.Fundamental research on effect of imidazoliumbased and phosphonium-based room temperature ionic liquids on coal oxidation properties[D]. Xuzhou:China University of Mining and Technology,2013.
[19]相建华,曾凡桂,梁虎珍,等.不同变质程度煤的碳结构特征及其演化机制[J].煤炭学报,2016,41(6):1498-1506.XIANG Jianhua,ZENG Fangui,LIANG Huzhen,et al.Carbon structure characteristics and evolution mechanism of different rank coals[J].Journal of China Coal Society,2016,41(6):1498-1506.
[20]李娜,刘全生,甄明,等.不同变质程度煤燃烧反应性及FTIR分析其热解过程结构变化[J].光谱学与光谱分析,2016,36(9):2760-2765.LI Na,LIU Quansheng,ZHEN Ming,et al.Coal combustion reactivity of different metamorphic degree and structure changes of FTIR analysis in pyrolysis process[J].Spectroscopy and Spectral Analysis,2016,36(9):2760-2765.
[21]张嬿妮,邓军,杨华,等.不同变质程度煤微观结构特征的试验研究[J].安全与环境学报,2014,14(4):67-71.ZHANG Yanni,DNEG Jun,YANG Hua,et al. Experimental study of the characteristic features of the microstructure of coal at different coal sorts[J].Journal of Safety and Environmen,2014,14(4):67-71.
[22] PARKER W J,JENKINS R J,BUTLER C P,et al.Flash method of determining thermal diffusivity,heat capacity,and thermal conductivity[J].Journal of Applied Physics,1961,32:1679-1684.
[23]张玉涛,史学强,李亚清,等.锌镁铝层状双氢氧化物对煤自燃的阻化特性[J].煤炭学报,2017,42(11):2892-2899.ZHANG Yutao,SHI Xueqiang,LI Yaqing,et al.Inhibiting effects of Zn/Mg/Al layer double hydroxide on coal spontaneous combustion[J].Journal of China Coal Society,2017,42(11):2892-2899.
[24]王兰云,徐永亮,姬宇鹏,等.含氧取代咪唑类离子液体影响煤结构及其氧化性质的实验研究[J].煤炭学报,2012,37(7):1190-1194.WANG Lanyun,XU Yongliang,JI Yupeng,et al.Effect of ionic liquids with imidazolium based cations substituted by different oxygen-containing groups on coal oxidation[J]. Journal of China Coal Society,2012,37(7):1190-1194.
[25]肖旸,李达江,吕慧菲,等.离子液体处理煤的低温氧化特性[J].煤炭转化,2018,41(6):15-21.XIAO Yang,LI Dajiang,LHuifei,et al. Experimental research on low-temperature oxidation characteristics of ionic liquid treated coal[J].Coal Conversion,2018,41(6):15-21.
[26]张卫清,蒋曙光,吴征艳,等.离子液体处理对煤微观活性结构的影响[J].中南大学学报(自然科学版),2013,44(5):2008-2013.ZHANG Weiqing,JIANG Shuguang,WU Zhengyan,et al. Influence of ionic liquids treatment on micro activity structure of coal[J].Journal of Central South University(Science and Technology),2013,44(5):2008-2013.
[27] DENG Jun,LI Qingwei,XIAO Yang,et al. Predictive models for thermal diffusivity and specific heat capacity of coals in Huainan mining area,China[J]. Thermochimica Acta,2017,656:101-111.
[28] ANNE M Hofmeister.Thermal diffusivity of garnets at high temperature[J].Physics and Chemistry of Minerals,2006,33:45-62.
[29]张卫清,蒋曙光,吴征艳,等.离子液体对煤中氢键反应活性的影响[J].中国矿业大学学报,2013,42(2):200-205.ZHANG Weiqing,JIANG Shuguang,WU Zhengyan,et al. Study of the effect ionic liquids have on hydrogen bonds of coal[J].Journal of China University of Mining and Technology,2013,42(2):200-205.
[30] DANIEL J Maloney,RAMANATHAN Sampath,JOHN W Zondlo.Heat capacity and thermal conductivity considerations for coal particles during the early stages of rapid heating[J]. Combustion and Flame,1999,116:94-104.
[31] HANKE C G,JOHANSSON A,HARPER J B,et al.Why are aromatic compounds more soluble than aliphatic compounds in dimethyimidazolium ionic liquids? Asimulation study[J]. Chemical Physics Letters,2003,374(1):85-90.
[32]赵新,殷冬媛,伍振毅.离子液体的研究现状及发展趋势[J].精细与专用化学品,2013,21(11):24-28.ZHAO Xin,YIN Dongyuan,WU Zhenyi.Research status and development trend of ionic liquids[J]. Fine and Specialty Chemicals,2013,21(11):24-28.
[2]潘乐书,杨永刚.基于量热分析煤低温氧化中活化能研究[J].煤炭工程,2013,45(6):102-105.PAN Leshu,YANG Yonggang.Study on activation energy of low temperature oxidation of coal based on calorimetry[J]. Coal Engineering,2013,45(6):102-105.
[3] XIAO Yang,LI Qingwei,DENG Jun,et al. Experimental study on the corresponding relationship between the index gases and critical temperature for coal spontaneous combustion[J]. Journal of Thermal Analysis and Calorimetry,2017,127:1009-1017.
[4] ZHANG Yutao,LIU Yurui,SHI Xueqiang,et al. Risk evaluation of coal spontaneous combustion on the basis of auto-ignition temperature[J].Fuel,2018,233:68-76.
[5] WEN Hu,LJunhui,XIAO Yang,et al. Temperature dependence of thermal conductivity,diffusion and specific heat capacity for coal and rocks from coalfield[J]. Thermochimica Acta,2015,619:41-47.
[6]肖旸,尹岚,马砺,等.不同预氧化温度下煤样热物性参数的实验研究[J].西安科技大学学报,2018,38(3):383-388.XIAO Yang,YIN Lan,MA Li,et al.Experimental study on coal thermo-physical parameters under the different peroxidation temperature[J].Journal of Xi’an University of Science and Technology,2018,38(3):383-388.
[7] DENG Jun,LI Qingwei,XIAO Yang,et al.Thermal diffusivity of coal and its predictive model in nitrogen and air atmospheres[J].Applied Thermal Engineering,2018,130:1233-1245.
[8] DENG Jun,REN Shuaijing,XIAO Yang,et al. Thermal properties of coals with different metamorphic levels in air atmosphere[J].Applied Thermal Engineering,2018,143:542-549.
[9] WANG Lanyun,XU Yongliang,JIANG Shuguang,et al.Imidazolium based ionic liquids affecting functional groups and oxidation properties of bituminous coal[J]. Safety Science,2012,50(7):1528-1534.
[10] WANG Lanyun,JIANG Shuguang,XU Yonglaing,et al. Effect of imidazolium based ionic liquids on coal exothermic oxidation by thermal analysis experiments[J]. Procedia Engineering,2011,26:647-651.
[11] ZHANG Weiqing,JIANG Shuguang,WU Zhengyan,et al.Influence of imidazolium-based ionic liquids on coal oxidation[J]. Fuel,2018,217:529-535.
[12] ZHANG Weiqing,JIANG Shuguang,HARDACRE Christopher,et al.Inhibitory effect of phosphonium-based ionic liquids on coal oxidation[J].Energy&Fuels,2014,28(7):4333-4341.
[13] ZHANG Weiqing,JIANG Shuguang,WANG Kai,et al.An experimental study of the effect of ionic liquids on the low temperature oxidation of coal[J]. International Journal of Mining Science and Technology,2012,22(5):687-691.
[14] XIAO Yang,LHuifei,YI Xin,et al.Treating bituminous coal with ionic liquids to inhibit coal spontaneous combustion[J]. Journal of Thermal Analysis&Calorimetry,2018. https://doi. org/10. 1007/s10973-018-7600-5.
[15] CUI Fusheng,BIN Laiwang,SHU Chimin,et al.Inhibiting effect of imidazolium-based ionic liquids on the spontaneous combustion characteristics of lignite[J].Fuel,2018,217:508-514.
[16] CUMMINGS Joshua,TREMAIN Priscilla,SHAH Kalpit,et al.Modification of lignites via low temperature ionic liquid treatment[J].Fuel Processing Technology,2017,155:51-58.
[17]邓军,陈炜乐,肖旸,等.咪唑类离子液体对煤热物性参数影响的实验研究[J].西安科技大学学报,2018,38(4):523-529.DENG Jun,CHEN Weile,XIAO Yang,et al.Experimental study on influence of imidazolium-based ionic liquids on thermo-physical parameters of coal[J]. Journal of Xi’an University of Science and Technology,2018,38(4):523-529.
[18]张卫清.咪唑类和季膦盐类室温离子液体影响煤氧化特性的基础研究[D].徐州:中国矿业大学,2013.ZHANG Weiqing.Fundamental research on effect of imidazoliumbased and phosphonium-based room temperature ionic liquids on coal oxidation properties[D]. Xuzhou:China University of Mining and Technology,2013.
[19]相建华,曾凡桂,梁虎珍,等.不同变质程度煤的碳结构特征及其演化机制[J].煤炭学报,2016,41(6):1498-1506.XIANG Jianhua,ZENG Fangui,LIANG Huzhen,et al.Carbon structure characteristics and evolution mechanism of different rank coals[J].Journal of China Coal Society,2016,41(6):1498-1506.
[20]李娜,刘全生,甄明,等.不同变质程度煤燃烧反应性及FTIR分析其热解过程结构变化[J].光谱学与光谱分析,2016,36(9):2760-2765.LI Na,LIU Quansheng,ZHEN Ming,et al.Coal combustion reactivity of different metamorphic degree and structure changes of FTIR analysis in pyrolysis process[J].Spectroscopy and Spectral Analysis,2016,36(9):2760-2765.
[21]张嬿妮,邓军,杨华,等.不同变质程度煤微观结构特征的试验研究[J].安全与环境学报,2014,14(4):67-71.ZHANG Yanni,DNEG Jun,YANG Hua,et al. Experimental study of the characteristic features of the microstructure of coal at different coal sorts[J].Journal of Safety and Environmen,2014,14(4):67-71.
[22] PARKER W J,JENKINS R J,BUTLER C P,et al.Flash method of determining thermal diffusivity,heat capacity,and thermal conductivity[J].Journal of Applied Physics,1961,32:1679-1684.
[23]张玉涛,史学强,李亚清,等.锌镁铝层状双氢氧化物对煤自燃的阻化特性[J].煤炭学报,2017,42(11):2892-2899.ZHANG Yutao,SHI Xueqiang,LI Yaqing,et al.Inhibiting effects of Zn/Mg/Al layer double hydroxide on coal spontaneous combustion[J].Journal of China Coal Society,2017,42(11):2892-2899.
[24]王兰云,徐永亮,姬宇鹏,等.含氧取代咪唑类离子液体影响煤结构及其氧化性质的实验研究[J].煤炭学报,2012,37(7):1190-1194.WANG Lanyun,XU Yongliang,JI Yupeng,et al.Effect of ionic liquids with imidazolium based cations substituted by different oxygen-containing groups on coal oxidation[J]. Journal of China Coal Society,2012,37(7):1190-1194.
[25]肖旸,李达江,吕慧菲,等.离子液体处理煤的低温氧化特性[J].煤炭转化,2018,41(6):15-21.XIAO Yang,LI Dajiang,LHuifei,et al. Experimental research on low-temperature oxidation characteristics of ionic liquid treated coal[J].Coal Conversion,2018,41(6):15-21.
[26]张卫清,蒋曙光,吴征艳,等.离子液体处理对煤微观活性结构的影响[J].中南大学学报(自然科学版),2013,44(5):2008-2013.ZHANG Weiqing,JIANG Shuguang,WU Zhengyan,et al. Influence of ionic liquids treatment on micro activity structure of coal[J].Journal of Central South University(Science and Technology),2013,44(5):2008-2013.
[27] DENG Jun,LI Qingwei,XIAO Yang,et al. Predictive models for thermal diffusivity and specific heat capacity of coals in Huainan mining area,China[J]. Thermochimica Acta,2017,656:101-111.
[28] ANNE M Hofmeister.Thermal diffusivity of garnets at high temperature[J].Physics and Chemistry of Minerals,2006,33:45-62.
[29]张卫清,蒋曙光,吴征艳,等.离子液体对煤中氢键反应活性的影响[J].中国矿业大学学报,2013,42(2):200-205.ZHANG Weiqing,JIANG Shuguang,WU Zhengyan,et al. Study of the effect ionic liquids have on hydrogen bonds of coal[J].Journal of China University of Mining and Technology,2013,42(2):200-205.
[30] DANIEL J Maloney,RAMANATHAN Sampath,JOHN W Zondlo.Heat capacity and thermal conductivity considerations for coal particles during the early stages of rapid heating[J]. Combustion and Flame,1999,116:94-104.
[31] HANKE C G,JOHANSSON A,HARPER J B,et al.Why are aromatic compounds more soluble than aliphatic compounds in dimethyimidazolium ionic liquids? Asimulation study[J]. Chemical Physics Letters,2003,374(1):85-90.
[32]赵新,殷冬媛,伍振毅.离子液体的研究现状及发展趋势[J].精细与专用化学品,2013,21(11):24-28.ZHAO Xin,YIN Dongyuan,WU Zhenyi.Research status and development trend of ionic liquids[J]. Fine and Specialty Chemicals,2013,21(11):24-28.