秸秆燃烧中钾逸出的几种模型的对比

为研究生物质燃烧中钾逸出模型的异同,针对现有几种常见的蒸发和动力学模型编写钾逸出速率的计算程序,并结合秸秆灰在同步热分析仪中的实验对各模型进行对比分析。结果表明：1）蒸发模型和张/曹的动力学模型都能较准确地预测秸秆中钾的逸出随温度变化的规律。2）Peters模型的最大值出现时刻向低温处偏离,而Fatehi模型的向高温处偏离。3）蒸发模型在以高升温速率（30和50 ℃/min）升至900 ℃时,与实验吻合最好（相对误差<20%）。该模型物理实质清晰,但由于未考虑钾盐之间的相互作用导致预测值略大于实验值。4）各动力学模型和实验表明,在900~950 ℃内秸秆中钾含量及升温速率的影响大于终温对钾逸出速率的影响。

COMPARISON OF MODELS FOR RELEASE OF POTASSIUM DURING AGRO-STALKS COMBUSTION

In order to compare models for potassium release during biomass combustion, codes of several typical evaporation and kinetic models were written to calculate the release rate of potassium. Calculation results were analyzed in comparison with the thermogravimetric analysis of ashes from agro-stalks. It shows that： （1） Predictions from evaporation model and Zhang/Cao’s kinetic models agree better with potassium release in respect of temperature than the others. （2） The maximum release rate of potassium in Peters’ model occurs at much lower temperature, while that in Fatehi model occurs at much higher temperature than experimental results. （3） A good agreement is obtained between the evaporation model and experiment （relative error <20%）, When temperature increases to 900 ℃ at high heating rate （30/50 ℃/min）. The physical mechanism of the evaporation model is clear, but the simulation is considerably larger than the experiment because of the neglect on interaction of potassium salts. （4） The kinetic models and experiments indicated that the effects of potassium content in straw and heating rate are greater than that of final temperature on the release rate of potassium at 900-950 ℃.