基于SLMD的生物质热解动力学预测模型

采用单纯形格子混合设计法(SLMD)对纤维素、半纤维素和木质素3种生物质组分进行复配优化设计,并在综合热分析仪上进行了热解试验。分析了3组分混合热解特性,建立了由生物质3组分比例直接计算动力学参数的预测模型,对模型进行了试验验证。结果表明:纤维素热解反应级数较低(1.20),活化能较高(134.50 k J/mol),指前因子较大(3.49×1012s-1),热解较为迅速与剧烈;半纤维素和木质素热解的反应级数较高(1.30、1.32),活化能较低(33.51、19.98 k J/mol),指前因子较小(9.43×103、107 s-1),热解较为缓慢;3组分在混合热解中对动力学参数存在交互影响,纤维素对活化能和指前因子的影响较为显著,而半纤维素与木质素对反应级数的影响较大;动力学参数预测模型精度较高,可有效预测生物质热解动力学参数。

Prediction Model of Biomass Pyrolysis Kinetic Based on SLMD

The mixing scheme of biomass constituents, including cellulose, hemicellulose and lignin, was designed by using simplex-lattice mixture design (SLMD) method. The pyrolysis characteristics of biomass constituents were observed by using a thermo-gravimetric analyzer and the kinetic parameters were calculated. In addition, a prediction model for kinetic parameters was established and the model was verified by test. The results showed that the reaction order n, activation energy E and frequency factor A of cellulose were 1.20, 134.50kJ/mol and 3.49×1012s-1, respectively. Pyrolysis of cellulose was much rapider and more violent than the other two components. The value of n, E.and A for hemicellulose were 1.30, 33.51kJ/mol and 9.43×103s-1 and that for lignin were 1.32, 19.98kJ/mol and 107s-1. Pyrolysis of hemicellulose and lignin were relatively slow. Furthermore, three components in the mixed pyrolysis had interaction effect. Effects on the activation energy and the frequency factor of cellulose were significant while effect on the reaction order of hemicellulose and lignin was remarkable. The kinetic model is precision and it can effectively predict the biomass pyrolysis kinetic parameters.