生物质热反应机理与活化能确定方法Ⅰ.干燥段研究

Thermal reaction mechanism of biomass and determination of activation energy Ⅰ.drying section

干燥段是生物质热解的第一个过程。采用热分析仪研究了杉木木屑干燥段质量和热量的变化,推导了非等温干燥动力学模型,探讨了热质传输机理。结果表明,随着温度的升高,木屑含湿量迅速下降,80℃左右出现一个明显的失重峰;非等温干燥动力学Page模型能很好地模拟木屑干燥过程,木屑干燥活化能为12.6 kJ/mol;水分传输与热量传递有紧密的耦合关系,干燥吸收的热量主要用于水分的扩散蒸发;木屑干燥需热量为426 kJ/kg,模拟值与实验值吻合较好。

The first step of biomass pyrolysis corresponds to water evaporation.Thermal analysis instrument was used to determine the mass and heat change of fir wood during drying process.Non-isothermal drying kinetics model was derived to explore the mechanism of heat and mass transfer.The results show that moisture content decreases rapidly and weight loss peak appears at 80 ℃.Page model for non-isothermal drying kinetics can well simulate wood drying process and the drying activation energy is 12.6 kJ/mol.Water and heat transfer have close relationship and the dry heat is mainly used for water evaporation.The value of heat requirement is 426 kJ/kg and the simulated results show good agreement with experimental values.