Kinetic analysis and thermodynamics properties of air/steam gasification of agricultural waste
Kinetic analysis and thermodynamics properties of air/steam gasification of agricultural waste
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DOI：
10.1016/j.jece.2020.103829
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发表时间：
2020-08
影响因子：
7.7
通讯作者：
Anabel Fernandez;L. Ortiz;Daniela Asensio;R. Rodríguez;G. Mazza
中科院分区：
文献类型：
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作者：
Anabel Fernandez;L. Ortiz;Daniela Asensio;R. Rodríguez;G. Mazza
采用宏观热重分析法研究了木屑（SD）、李子和橄榄核（PP、OP）生物废弃物在3种升温速率（5、10、15 K/min）下的空气/水蒸气气化过程。气化过程分为三个阶段：水分汽化、脱挥发分和半焦气化。采用Flynn-Wall-Ozawa（FWO）、分布活化能模型（DAEM）、Friedman、Starink和Kissinger-Akahira-Sunose（KAS）等5种无模型方法对实验数据进行分析，评价气化动力学参数。FWO方法表现出最好的拟合实验结果。使用Kissinger表达式估计指前因子。焦炭气化步骤的平均表观活化能（E）为218.27（SD）、143.70（PP）和87.89 kJ mol−1（OP）。指前因子分别为6.93 × 1023（SD）、5.10 × 1014（PP）和3.71 × 1009 s-1（OP）。全球CO释放的E值分别为87.34（SD）、67.19（PP）和133.23 kJ mol−1（OP）。此外，用FWO方法计算了热力学参数ΔS、ΔH和ΔG。ΔH为正值，表明在整个转化度范围内气化过程具有整体吸热性，ΔG平均值分别为130.53（SD）、148.17（PP）和132.91 kJ mol−1（OP）。ΔS和ΔG的平均值以及Arrhenius动力学系数表明，反应活性的大小顺序为：SD > OP > PP。结果与以前报道的数据吻合良好。
The air/steam gasification of wood sawdust (SD), plum and olive pits (PP, OP) bio-wastes was studied using macro-thermogravimetric analysis at three heating rates (5, 10, 15 K/min). Three stages were identified during gasification process: water vaporization; de-volatilization and char gasification. The experimental data were analysed by applying five model-free methods: Flynn-Wall-Ozawa (FWO), Distributed Activation Energy Model (DAEM), Friedman, Starink, and Kissinger-Akahira-Sunose (KAS), to evaluate the gasification kinetic parameters. The FWO method exhibited the best fit to the experimental results. The pre-exponential factor was estimated using the Kissinger’s expression. The average apparent activation energy (E) for the char-gasification step was found to be 218.27 (SD), 143.70 (PP) and 87.89 kJ mol−1(OP). The pre-exponential factors were 6.93 1023(SD), 5.10 1014(PP), and 3.71 1009s−1(OP).A kinetic model to predict the CO release during the bio-waste decomposition was also proposed and validated. The E values for global release of CO were 87.34 (SD), 67.19 (PP), and 133.23 kJ mol−1(OP). In addition, the thermodynamic parameters ΔS, ΔH and ΔG were calculated from the FWO method. The positive values of ΔH evidenced the global endothermicity of the gasification process over the whole range of the conversion degree.The average ΔG values were 130.53 (SD), 148.17 (PP) and 132.91 kJ mol−1(OP). The average ΔS and ΔG values, together with the Arrhenius kinetic coefficient showed that the reactivity for gasification decreased in the following order: SD > OP > PP. The results are in good agreement with previously reported data.