咪唑类离子液体处理煤热失重以及传热特性
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摘要
离子液体作为新型阻化剂,溶解破坏煤中的活性结构从而抑制煤氧化反应进程,达到阻化煤自燃的效果。为了考察咪唑类离子液体对煤热失重以及热传递特性的影响,采集淮南矿区丁集1/3焦煤作为实验煤样,选取[EMIM][BF4],[BMIM][BF4],[BMIM][NO3]和[BMIM][I]对焦煤处理,并将未处理煤样作为对照组,开展热重-差热同步热分析实验和激光导热实验,得出咪唑类离子液体处理煤的热失重和热物性参数。结果表明:离子液体对煤的氧化热失重过程有明显的减弱作用,且不同离子液体的作用效果不同,效果最好的为[BMIM][BF4]。此外,差热结果显示离子液体处理煤的放热量均低于离子液体未处理煤,其中[BMIM][BF4]处理煤相比较于原煤,波峰温度提高28℃。煤样的热物性参数呈现出阶段性变化。30～210℃,随着温度的增加,煤样的热扩散系数逐渐降低,比热容和导热系数逐渐增大; 210℃之后,煤样的热扩散系数逐渐上升,比热容趋于平稳,导热系数快速上升。在同一温度下,离子液体处理煤的热扩散系数以及导热系数均低于原煤,离子液体处理煤的比热容均高于原煤,其中[BMIM][BF4]处理煤的热扩散系数最小,比热容最大,导热系数最小。此外,[BMIM][BF4]处理煤热物性参数变化率最低,对温度的敏感性明显减弱,对煤热量传递抑制作用明显。结果可为煤火的防治提供一定的理论基础和现实依据。
Ionic liquids( ILs) is a new type inhibitor,which can dissolve and destroy the active functional structures in coal to inhibit coal oxidation process and achieve the inhibitor effect of coal spontaneous combustion.To investigate the effect of imidazolium-based ILs on the weigh loss and heat transfer of coal,1/3 coking coal of Dingji in Huainan Mining Area was collected as experimental coal,which was treated by ILs for[EMIM][BF4],[BMIM][BF4],[BMIM][NO3],and[BMIM][I],with IL-untreated( IL-untc) coal acting as the control group,synchronous thermal analyzer( TG-DSC) and Laser pyrometer experiment were employed to obtain weight loss and thermophysical parameters of imidazolium-based ionic liquids treatment coal.The results showed that ILs on coal spontaneous combustion process had a significantly reduced mass loss,the best effect was[BMIM][BF4].Moreover,the results of differential thermal analysis showed that the heat release of ILs-treated coal samples were lower than IL-untc coal,of which the peak temperature of the[BMIM][BF4]treated coal sample increased 28 ℃.Thermophysical parameters for all coal samples presented a phased variation.With the elevation of temperature between 30 to 210 ℃,thermal diffusivity gradually decreased,specific heat capacity and thermal conductivity increased.However,when the temperature was beyond 210 ℃,thermal diffusivity increased,the increasing tendency of specific heat capacity was weak and thermal conductivity rapidly increased.In a same temperature,the thermal diffusivity and thermal conductivity of IL-treated coal were lower than that of raw coal,and the specific heat capacity is higher than that of raw coal.The smallest thermal diffusivity and thermal conductivity,and the biggest specific heat capacity were found for[BMIM][BF4]treated coal.Furthermore,the sensitivity of[BMIM][BF4]treated coal on temperature obviously weakened,which indicated that the inhabiting effect of[BMIM][BF4]on heat transfer was stronger.These results provide a theoretical basis and realistic guidance for the prevention of coal fire.
Ionic liquids( ILs) is a new type inhibitor,which can dissolve and destroy the active functional structures in coal to inhibit coal oxidation process and achieve the inhibitor effect of coal spontaneous combustion.To investigate the effect of imidazolium-based ILs on the weigh loss and heat transfer of coal,1/3 coking coal of Dingji in Huainan Mining Area was collected as experimental coal,which was treated by ILs for[EMIM][BF4],[BMIM][BF4],[BMIM][NO3],and[BMIM][I],with IL-untreated( IL-untc) coal acting as the control group,synchronous thermal analyzer( TG-DSC) and Laser pyrometer experiment were employed to obtain weight loss and thermophysical parameters of imidazolium-based ionic liquids treatment coal.The results showed that ILs on coal spontaneous combustion process had a significantly reduced mass loss,the best effect was[BMIM][BF4].Moreover,the results of differential thermal analysis showed that the heat release of ILs-treated coal samples were lower than IL-untc coal,of which the peak temperature of the[BMIM][BF4]treated coal sample increased 28 ℃.Thermophysical parameters for all coal samples presented a phased variation.With the elevation of temperature between 30 to 210 ℃,thermal diffusivity gradually decreased,specific heat capacity and thermal conductivity increased.However,when the temperature was beyond 210 ℃,thermal diffusivity increased,the increasing tendency of specific heat capacity was weak and thermal conductivity rapidly increased.In a same temperature,the thermal diffusivity and thermal conductivity of IL-treated coal were lower than that of raw coal,and the specific heat capacity is higher than that of raw coal.The smallest thermal diffusivity and thermal conductivity,and the biggest specific heat capacity were found for[BMIM][BF4]treated coal.Furthermore,the sensitivity of[BMIM][BF4]treated coal on temperature obviously weakened,which indicated that the inhabiting effect of[BMIM][BF4]on heat transfer was stronger.These results provide a theoretical basis and realistic guidance for the prevention of coal fire.
引文
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[15]王兰云,蒋曙光,吴征艳,等.离子液体抑制煤炭自燃的新设想[J].煤矿安全,2009,40(8):89-92.WANG Lanyun,JIANG Shuguang,WU Zhengyan,et al.A new idea of inhibition on coal spontaneous combustion by ionic liquid[J].Safety in Coal Mines,2009,40(8):90-92.
[16] WANG L,XU Y,JIANG S,et al.Imidazolium based ionic liquids affecting functional groups and oxidation properties of bituminous coal[J].Safety Science,2012,50(7):1528-1534.
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[21] COWAN R D. Proposed method of measuring thermal diffusivity at high temperatures[J]. Journal of Applied Physics,1961,32(7):1363-1370.
[22] COWAN R D. Pulse method of measuring thermal diffusivity at high temperatures[J]. Journal of Applied Physics,1963,34(4):926-927.
[23]王威.利用热重分析研究煤的氧化反应过程及特征温度[D].西安:西安科技大学,2005.WANG Wei. Application of Research of the Thermogravimetric Analysis in the Oxidation procession of Coal[D].Xi’an:Xi’an University of Science and Technology,2005.
[24] XIAO Y,LH F,HUANG A C,et al.A new numerical method to predict the growth temperature of spontaneous combustion of 1/3 coking coal[J]. Applied Thermal Engineering,2018,131(25):221-229.
[25] BENFELL K E,BEAMISH B B,RODGERS K A.Thermogravimetric analytical procedures for characterizing New Zealand and Eastern Australian coals[J]. Thermochimica Acta,1996,286(1):67-74.
[26] KIZGUT S,YILMAZ S. Characterization and non-isothermal decomposition kinetics of some Turkish bituminous coals by thermal analysis[J].Fuel Processing Technology,2004,85(2):103-111.
[27]王凯.陕北侏罗纪煤氧化自燃特性实验研究[D].西安:西安科技大学,2013.WANG Kai. Study on the oxidation and spontaneous combustion characteristics of Jurassic coal in northern Shaanxi[D].Xi’an:Xi’an University of Science and Technology,2013.
[28]苏怀兴.褐煤中水分存在形式的实验研究[D].鞍山:辽宁科技大学,2014.SU Huaixing.An experimental study on the existing form of water in lignite[D]. Anshan:Liaoning University of Science and Technology,2014.
[29] 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.
[30] MOSTAFA M,AFIFY N,GABER A,et al.Investigation of thermal properties of some basalt samples in Egypt[J]. Journal of Thermal Analysis and Calorimetry,2004,75(1):179-188.
[31] ABDULAGATOV I M,ABDULAGATOVA Z Z,KALLAEV S N,et al.Thermal-diffusivity and heat-capacity measurements of sandstone at high temperatures using laser flash and DSC methods[J]. International Journal of Thermophysics,2015,36(4):658-691.
[32]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.
[33] MALONEY D J,SAMPATH R,ZONDLO J W. Heat capacity and thermal conductivity considerations for coal particles during the early stages of rapid heating[J]. Combustion and Flame,1999,116(1):94-104.
[34]鲁军辉.煤田火区煤岩体热物性参数及热破坏特性研究[D].西安:西安科技大学,2016.LU Junhui.Research on Thermal physical parameters and destruction characteristics of coal and rock of coalfield fire area[D].Xi’an:Xi’an University of Science and Technology,2016.
[35]耿胜楚,范天博,刘云义.离子液体[BMIm]BF4在神华煤溶胀预处理中的应用[J].煤炭转化,2010,33(2):35-38.GENG Shengchu,FAN Tianbo,LIU Yunyi.Application of ionic liquid[BMIm]BF4 in swelling pretreatment of ShenHua coal[J].2010,33(2):35-38.
[2] MARK Christopher.Coal bursts in the deep longwall mines of the United States[J].International Journal of Coal Science&Technology,2016,3(1):1-9.
[3] DENG Jun,XIAO Yang,LI Qingwei,et al.Experimental studies of spontaneous combustion and anaerobic cooling of coal[J]. Fuel,2015,157(1):261-269.
[4] MAO Zhanli,ZHU Hongya,ZHAO Xuejuan,et al.Experimental study on characteristic parameters of coal spontaneous combustion[J].Procedia Engineering,2013,62:1081-1086.
[5]金永飞,郭军,文虎,等.煤自燃高温贫氧氧化燃烧特性参数的实验研究[J].煤炭学报,2015,40(3):596-602.JIN Yongfei,GUO Jun,WEN Hu,et al. Experimental study on the high temperature lean oxygen oxidation combustion characteristic parameters of coal spontaneous combustion[J]. Journal of China Coal Society,2015,40(3):576-602.
[6] DENG Jun,MA Xiaofeng,ZHANG Yutao,et al. Effects of pyrite on the spontaneous combustion of coal[J]. International Journal of Coal Science&Technology,2015,2(4):306-311.
[7] 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(10):101-111.
[8] MOTTAGHY D,VOSTEEN H D,SCHELLSCHMIDT R. Temperature dependence of the relationship of thermal diffusivity versus thermal conductivity for crystalline rocks[J].International Journal of Earth Sciences,2008,97(2):435-442.
[9] GOSSET D,GUILLOIS O,PAPOULAR R. Thermal diffusivity of compacted coal powders[J].Carbon,1996,34(3):369-373.
[10] WEN H,LU J,XIAO Y,et al. Temperature dependence of thermal conductivity,diffusion and specific heat capacity for coal and rocks from coalfield[J].Thermochimica Acta,2015,619(10):41-47.
[11] DENG J,LI Q W,XIAO Y,et al.Experimental study on the thermal properties of coal during pyrolysis,oxidation,and re-oxidation[J].Applied Thermal Engineering,2017,110(5):1137-1152.
[12] BRANDT A,GRASVIK J,HALLETT J P,et al.Deconstruction of lignocellulosic biomass with ionic liquids[J]. Green Chemistry,2013,15(3):550-583.
[13] ROGERS R D,SEDDON K R.Ionic liquids-solvents of the future?[J].Science,2003,302(5646):792-793.
[14] ANDERSON J L,DING J,WELTON T,et al.Characterizing ionic liquids on the basis of multiple solvation interactions[J]. Journal of the American Chemical Society,2002,124(47):14247-14254.
[15]王兰云,蒋曙光,吴征艳,等.离子液体抑制煤炭自燃的新设想[J].煤矿安全,2009,40(8):89-92.WANG Lanyun,JIANG Shuguang,WU Zhengyan,et al.A new idea of inhibition on coal spontaneous combustion by ionic liquid[J].Safety in Coal Mines,2009,40(8):90-92.
[16] WANG L,XU Y,JIANG S,et al.Imidazolium based ionic liquids affecting functional groups and oxidation properties of bituminous coal[J].Safety Science,2012,50(7):1528-1534.
[17] ZHANG W Q,JIANG S G,WANG K,et al.Study on coal spontaneous combustion characteristic structures affected by ionic liquids[J].Procedia Engineering,2011,26:480-485.
[18] CUMMINGS J,TREMAIN P,SHAH K,et al.Modification of lignites via low temperature ionic liquid treatment[J]. Fuel Processing Technology,2017,155:51-58.
[19]肖旸,钟凯琪,解萌玥,等.离子液体抑制煤自燃的程序升温试验研究[J].西安科技大学学报,2017,37(3):396-402.XIAO Yang,ZHONG Kaiqi,XIE Mengyue,et al. Experimental research on ionic liquid inhibitors to inhibit coal spontaneous combustion[J]. Journal of Xi’an University of Science and Technology,2017,37(3):396-402.
[20] PARKER W J,JENKINS R J.Thermal conductivity measurements on bismuth telluride in the presence of a 2MeV electron beam[J].Advanced Energy Conversion,1962,2:87-103.
[21] COWAN R D. Proposed method of measuring thermal diffusivity at high temperatures[J]. Journal of Applied Physics,1961,32(7):1363-1370.
[22] COWAN R D. Pulse method of measuring thermal diffusivity at high temperatures[J]. Journal of Applied Physics,1963,34(4):926-927.
[23]王威.利用热重分析研究煤的氧化反应过程及特征温度[D].西安:西安科技大学,2005.WANG Wei. Application of Research of the Thermogravimetric Analysis in the Oxidation procession of Coal[D].Xi’an:Xi’an University of Science and Technology,2005.
[24] XIAO Y,LH F,HUANG A C,et al.A new numerical method to predict the growth temperature of spontaneous combustion of 1/3 coking coal[J]. Applied Thermal Engineering,2018,131(25):221-229.
[25] BENFELL K E,BEAMISH B B,RODGERS K A.Thermogravimetric analytical procedures for characterizing New Zealand and Eastern Australian coals[J]. Thermochimica Acta,1996,286(1):67-74.
[26] KIZGUT S,YILMAZ S. Characterization and non-isothermal decomposition kinetics of some Turkish bituminous coals by thermal analysis[J].Fuel Processing Technology,2004,85(2):103-111.
[27]王凯.陕北侏罗纪煤氧化自燃特性实验研究[D].西安:西安科技大学,2013.WANG Kai. Study on the oxidation and spontaneous combustion characteristics of Jurassic coal in northern Shaanxi[D].Xi’an:Xi’an University of Science and Technology,2013.
[28]苏怀兴.褐煤中水分存在形式的实验研究[D].鞍山:辽宁科技大学,2014.SU Huaixing.An experimental study on the existing form of water in lignite[D]. Anshan:Liaoning University of Science and Technology,2014.
[29] 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.
[30] MOSTAFA M,AFIFY N,GABER A,et al.Investigation of thermal properties of some basalt samples in Egypt[J]. Journal of Thermal Analysis and Calorimetry,2004,75(1):179-188.
[31] ABDULAGATOV I M,ABDULAGATOVA Z Z,KALLAEV S N,et al.Thermal-diffusivity and heat-capacity measurements of sandstone at high temperatures using laser flash and DSC methods[J]. International Journal of Thermophysics,2015,36(4):658-691.
[32]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.
[33] MALONEY D J,SAMPATH R,ZONDLO J W. Heat capacity and thermal conductivity considerations for coal particles during the early stages of rapid heating[J]. Combustion and Flame,1999,116(1):94-104.
[34]鲁军辉.煤田火区煤岩体热物性参数及热破坏特性研究[D].西安:西安科技大学,2016.LU Junhui.Research on Thermal physical parameters and destruction characteristics of coal and rock of coalfield fire area[D].Xi’an:Xi’an University of Science and Technology,2016.
[35]耿胜楚,范天博,刘云义.离子液体[BMIm]BF4在神华煤溶胀预处理中的应用[J].煤炭转化,2010,33(2):35-38.GENG Shengchu,FAN Tianbo,LIU Yunyi.Application of ionic liquid[BMIm]BF4 in swelling pretreatment of ShenHua coal[J].2010,33(2):35-38.