温度对4种典型生物质成型特性的影响

以玉米秸秆、桉木屑、竹屑、硬杂木屑4种典型生物质为原料进行成型实验，研究了温度对其成型特性的影响。在差示扫描量热仪上测定了4种原料的热转变特征温度，显示玻璃态转变特征温度T_g在80~100℃之间。40℃时松弛密度（D_RS）和径向最大抗压力（M_RS）较低，成型比能耗（E_SC）较高；70~100℃时松弛密度和径向最大抗压力增大，成型比能耗降低；100~160℃时松弛密度增加，径向最大抗压力无一致性变化规律，比能耗增大；100℃左右接近4种原料玻璃态转化的终止温度，存在比能耗最低点，说明粒子达到最大软化程度，易于发生形变；原料木质素含量越高成型后颗粒的径向最大抗压力越大，成型时的比能耗越高。成型颗粒内部横断面的微观形貌测试结果显示低于原料玻璃态转变温度时，粒子间存在较大缝隙，结合不紧密；高于原料玻璃态转变温度时，粒子间缝隙较少，结合紧密。

Effects of Temperature on Pelletization of Four Typical Types of Biomass

Four typical types of biomasses, corn stover, eucalyptus sawdust, bamboo sawdust and hardwood sawdust, were used as raw materials to analyze the effects of temperature and material chemical composition on the properties of pellets by conducting single pellet making experiments. The characteristic thermal transition temperatures of the four raw materials were measured using a differential scanning calorimetry and found the glass transition temperatures(T_g) were in the temperature range of 80-100℃. It was found that the relaxed density(D_RS) and radial maximum stress(M_RS) were lower and the specific energy consumption(E_SC) was higher at 40℃, the relaxed density and radial maximum stress increased and the specific energy consumption decreased in the temperature range of 70-100℃, the relaxed density increased and the radial maximum stress did not present consistent change law and the specific energy consumption increased in the temperature range of 100-160℃. The lowest specific energy consumption located at 100℃ during the characteristic thermal transition temperature range. Besides, the higher the raw material lignin content was, the higher the specific energy consumption and the radial maximum stress were. The micromorphology of the internal cross section of the pellets showed that there were large gaps between the particles at the temperature of lower than the onset of the glass transition temperature and there were few gaps between the particles at the temperature of higher than the endpoint of the glass transition temperature.