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采用热重分析技术对中国典型农业生物质废弃物(玉米秆、稻草和棉秆)的热解行为及其动力学规律进行了研究,定量分析了升温速率对生物质热解特性的影响规律,建立了生物质热解的反应动力学模型。结果表明,农业生物质的热解表现出相似的规律,热分解主要集中在200～400?℃。在升温速率为10?℃/min时,玉米秆、稻草和棉秆分别在347.6、315.4和345.2?℃取得最大反应速率8.00、7.35和7.68%/min,当温度达到900?℃时,焦炭产率分别为24.5%、30.8%和20.7%。在低升温速率下,挥发分析出阶段的起始温度与升温速率的对数呈线性关系,最大热解速率随着升温速率的增大呈线性增大趋势。三组分模型可以很好地模拟木质纤维类生物质在不同升温速率下的热解行为。纤维素分解对生物质热解的贡献最大,半纤维素次之,而木质素最小。
The pyrolysis behavior and kinetics of typical agricultural biomass wastes (corn stalks, straw and cotton stalks) in China were studied by using thermogravimetric analysis (TGA), and the influence of heating rate on the pyrolysis characteristics of biomass was quantitatively analyzed. The reaction kinetic model of biomass pyrolysis was established. The results showed that the pyrolysis of agricultural biomass showed a similar pattern, and the thermal decomposition was mainly concentrated in the range of 200-400 ℃. At the heating rate of 10 ℃ / min, the maximal reaction rates of corn stalk, straw and cotton stalk were obtained at 347.6, 315.4 and 345.2 ℃, respectively. The maximum reaction rates were 8.00, 7.35 and 7.68% / min. When the temperature reached 900 ℃, Rates were 24.5%, 30.8% and 20.7% respectively. At the low heating rate, the initial temperature of the volatilization stage is linear with the logarithm of the heating rate, and the maximum pyrolysis rate increases linearly with increasing heating rate. The three-component model can well simulate the pyrolysis behavior of lignocellulosic biomass at different heating rates. Cellulose decomposition contributes the most to biomass pyrolysis, followed by hemicellulose and lignin.