Heat transfer in the process of pyrolysis of garden waste
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摘要: 为了更加准确地控制实际生产中热解物各部分的温度、提高园林废弃物的处理效率及处理质量、更好地利用园林废弃物热解后得到的产物,对园林废弃物热解过程中的热量传递问题进行研究。从测量园林废弃物热解过程中的温度分布及变化入手,了解热解过程中的热量传递特征,并在此基础上通过热力学分析建立热解传热模型,利用ANSYS有限元软件对所建模型进行模拟求解。对比分析模拟结果与试验数据后,根据实际情况对模型相关参数进行优化,最终获得了具有一定应用价值的热解传热模型。在此过程中不仅得到热解过程中反应器内的温度分布,还得知热解温度、物料多少、物料所处位置等因素都对热解过程中的热量传递有明显影响;相同条件下,热解温度越高、热解物料越少,则热量传递越强;同一时间内,温度梯度较大的位置热量传递较强;根据热解过程中反应烧瓶瓶壁上的温度载荷、物料表面的对流换热载荷不是恒定的这一现象,建立了侧壁温度关于木粉高度以及木粉上方流体温度关于时间的函数关系式。Abstract: Temperature has a significant effect on pyrolysis and determines the components of pyrolysis products. The distribution of pyrolysate temperature, however, relies on the heat transfer characteristics during the pyrolysis process. To study the heat transfer characteristics during the pyrolysis process of garden waste, the temperature distribution and variation in garden waste were measured. The software ANSYS was taken to simulate the heat transfer process, and the heat transfer model was established by comparative analysis of the experimental data and the simulation value. The results indicated that the heat transfer ability increased along with ascending pyrolysis temperatures and decreased along with the increase of the amount of garden waste; the heat transfer ability was proportional to temperature gradient. Simultaneously, the relationship between the temperature on flask lateral wall and the height of garden waste powder, and the relationship between the temperature above garden waste powder and time were established based on the phenomenon that the temperature load on the reaction flask wall and the convective heat transfer load on the garden waste powder surface were not constant. This study, to a certain extent, will provide theoretical guidance to garden waste pyrolysis.
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Key words:
- garden waste /
- pyrolysis /
- heat transfer /
- temperature distribution
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