温度对玉米秆烘焙及热解的影响

EFFECT OF TEMPERATURE CONDITIONS ON CORNSTALKS TORREFACTION AND PYROLYSIS

为了研究生物质烘焙后冷却速度对其表面形貌及后续热解产生的影响,以不同温度(200、230、260、290℃)对玉米秆进行烘焙,并用快速冷却(TF)与缓慢冷却(TS)两种方式进行降温处理。采用扫描电镜(SEM)观察烘焙前后样品的表面形貌发现,TS样品表面相比同一烘焙温度下TF样品及原样表面更加疏松;将烘焙前后样品放入热重分析仪中进行热解实验得出,随着烘焙温度的升高,样品的最大失重速率总体呈下降趋势;同一烘焙温度下,TS样品与TF样品的最大失重速率相差不大,290℃烘焙温度下TS样品的最大失重速率最慢,为2.94%/℃;在200、230、290℃烘焙温度下TS样品的热解活化能均小于TF样品,260℃时则相反,且其TS样品的活化能最高,达到100.43 kJ/mol。

In order to study the effect of cooling rate on the surface morphology and subsequent pyrolysis,cornstalks were torrefied at different temperatures(200,230,260 and 290 ℃),and were cooled by two methods:fast cooling(TF)and slow cooling(TS).Scanning electron microscopy(SEM)was used to observe the surface morphology of the raw and torrefied samples. It was found that the surface of TS samples was looser than that of TF and raw samples at the same torrefaction temperature. The samples were also put into thermogravimetric analyzer for pyrolysis experiments. The results showed that the maximum weight loss rates of all the torrefied samples decreased with the increasing torrefaction temperature. The maximum weight loss rate of TS samples and TF samples showed little difference at the same torrefaction temperature,and the lowest maximum weight loss rate of TS samples was 2.94%/℃ at 290 ℃. At the same time,the higher the torrefaction temperature,the higher the peak temperature corresponding to the maximum weight loss rate. The pyrolysis activation energy of TS samples at 200,230 and 290 ℃ were lower than that of TF samples at the same temperature,respectively,but it was opposite for TS260 sample,which has the highest activation energy about 100.43 kJ/mol.