Abstract: The non-isothermal gasification behavior of coal char with CO₂ was comparatively studied in the newly developed micro fluidized bed reaction analyzer (MFBRA) and a commercial thermogravimetric analyzer (TGA). The reaction kinetics data were calculated according to the methods of single heating rate and combination heating rate. The experimental data demonstrated that heating rate had obvious influence on coal char gasification. Increasing heating rate evidently increased reaction initiation temperature (T_x≈0), and reaction temperature corresponding to the maximum reaction rate (T_Rmax), but it gradually decreased char conversion at a given temperature and the activation energy estimated by the method of single heating rate. Comparing the results from TGA and MFBRA at the same heating rate clarified that both T_x≈0 and T_Rmax were relatively lower for MFBRA, and the higher the heating rate, the larger the difference between MFBRA and TGA. The measurement using MFBRA led to higher activation energy for char-CO₂ gasification, no matter the adopted estimation method of single heating rate (≥5℃·min^-1) or combination heating rate. The difference in kinetics data tested by TGA and MFBRA at higher heating rate (≥5℃·min^-1) could be much related to better heat transfer and lower diffusion inhibition.

Key words: micro fluidized bed, thermogravimetric analyzer, char, gasification, reaction kinetics, non-isothermal reaction, numerical analysis

摘要： 利用微型流化床反应分析仪(MFBRA)和热重分析仪(TGA)比较煤焦与CO₂的非等温气化反应特性,并利用单一升温速率法和组合升温速率法计算反应动力学数据。结果表明:升温速率对半焦非等温气化过程有重要影响,随着升温速率的增大,起始反应温度和最大反应速率对应的气化温度增加,同一气化温度下的碳转化率降低,而且利用单一升温速率法求取气化反应的活化能逐渐减小。与TGA相比,同一升温速率下,MFBRA中半焦气化反应的起始反应温度和最大反应速率对应的反应温度明显较小,而且升温速率越大差异越显著。无论是单一升温速率法(升温速率≥5℃·min^-1)还是组合升温速率法,TGA测得的动力学数据均明显小于MFBRA测得的动力学数据。高升温速率下(升温速率≥5℃·min^-1)半焦在TGA和MFBRA中非等温气化行为和动力学数据的差异很可能与MFBRA内较好的热量传递和受扩散的抑制作用较小有关。

关键词: 微型流化床, 热重, 半焦, 气化, 反应动力学, 非等温反应, 数值分析