Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser...Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser for the staged pyrolysis gasification process of pulverized coal.In this study,the non-isothermal pyrolysis behavior and kinetics of coal were examined at different heating rates(30,50,100,300,500,700,and 900℃/min)using thermogravimetry(TG)coupled with Fourier-transform infrared spectroscopy.Analysis of the TG/derivative TG(TG/DTG)curves indicated that coal pyrolysis mainly occurred between 300℃ and 700℃.Higher heating rates led to more volatiles being released from the coal,and a higher temperature was required to achieve rapid pyrolysis.Kinetic analysis showed that both the model-free methods(Friedman,Flynn-Wall-Ozawa,and Kissinger-Akahira-Sunose)and the model-based method(Coats-Redfern)effectively describe the coal pyrolysis process.The change in the Ea values between the two kinetic models was consistent throughout the pyrolysis process,and the most probable mechanism was the F2 model(secondary chemical reaction).In addition,the heating rate did not change the overall reaction order of the pyrolysis process;however,a higher heating rate resulted in a decrease in the Ea value during the initial pyrolysis stage.展开更多
采用热重分析(TGA)和傅里叶红外光谱(FTIR)联用实验技术以及13 C核磁共振(13 C NMR)技术,详细研究了印尼油砂热解产气过程和油砂沥青质的化学结构变化。油砂热解产气的TG-FTIR分析显示,油砂热解过程可以分为水分蒸发段(0~150℃)、低温段...采用热重分析(TGA)和傅里叶红外光谱(FTIR)联用实验技术以及13 C核磁共振(13 C NMR)技术,详细研究了印尼油砂热解产气过程和油砂沥青质的化学结构变化。油砂热解产气的TG-FTIR分析显示,油砂热解过程可以分为水分蒸发段(0~150℃)、低温段(150~550℃)和高温段(550~800℃)3个阶段,油气的析出主要集中在低温段,样品失重量为21%;在低温段所得油气的主要红外吸收峰归属于亚甲基和次甲基的C—H伸缩振动以及甲基的C—H面内弯曲振动。采用13C NMR技术获得了不同终温下沥青质碳结构骨架参数,由此揭示出油砂热解过程中化学结构的变化规律。随着油砂热解温度升高,沥青质中芳香族碳数量略有增加,脂肪族碳数量减少,其中亚甲基碳数量大幅度减小,是产油的主要贡献者,但甲基碳数量变化不明显;脂链平均长度不断减小,从9.2下降到4.0;油潜力碳的比例由0.56下降到0.27;在热解末期即产油能力最低时,惰性碳的比例占到0.6。2种实验结果相互印证且吻合良好。展开更多
基金the financial support from the National Natural Science Foundation of China(Grant No.21576293 and 21576294)。
文摘Coal pyrolysis is a fundamental reaction in the thermal processing and utilization of coal.Investigating the behavior and kinetics of coal pyrolysis is crucial for optimizing,designing,and developing a composite riser for the staged pyrolysis gasification process of pulverized coal.In this study,the non-isothermal pyrolysis behavior and kinetics of coal were examined at different heating rates(30,50,100,300,500,700,and 900℃/min)using thermogravimetry(TG)coupled with Fourier-transform infrared spectroscopy.Analysis of the TG/derivative TG(TG/DTG)curves indicated that coal pyrolysis mainly occurred between 300℃ and 700℃.Higher heating rates led to more volatiles being released from the coal,and a higher temperature was required to achieve rapid pyrolysis.Kinetic analysis showed that both the model-free methods(Friedman,Flynn-Wall-Ozawa,and Kissinger-Akahira-Sunose)and the model-based method(Coats-Redfern)effectively describe the coal pyrolysis process.The change in the Ea values between the two kinetic models was consistent throughout the pyrolysis process,and the most probable mechanism was the F2 model(secondary chemical reaction).In addition,the heating rate did not change the overall reaction order of the pyrolysis process;however,a higher heating rate resulted in a decrease in the Ea value during the initial pyrolysis stage.
文摘采用热重分析(TGA)和傅里叶红外光谱(FTIR)联用实验技术以及13 C核磁共振(13 C NMR)技术,详细研究了印尼油砂热解产气过程和油砂沥青质的化学结构变化。油砂热解产气的TG-FTIR分析显示,油砂热解过程可以分为水分蒸发段(0~150℃)、低温段(150~550℃)和高温段(550~800℃)3个阶段,油气的析出主要集中在低温段,样品失重量为21%;在低温段所得油气的主要红外吸收峰归属于亚甲基和次甲基的C—H伸缩振动以及甲基的C—H面内弯曲振动。采用13C NMR技术获得了不同终温下沥青质碳结构骨架参数,由此揭示出油砂热解过程中化学结构的变化规律。随着油砂热解温度升高,沥青质中芳香族碳数量略有增加,脂肪族碳数量减少,其中亚甲基碳数量大幅度减小,是产油的主要贡献者,但甲基碳数量变化不明显;脂链平均长度不断减小,从9.2下降到4.0;油潜力碳的比例由0.56下降到0.27;在热解末期即产油能力最低时,惰性碳的比例占到0.6。2种实验结果相互印证且吻合良好。
