Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science & Technology, Dalian University of Technology, Dalian, 116024, PR China.
Chemosphere. 2022 Feb;289:133009. doi: 10.1016/j.chemosphere.2021.133009. Epub 2021 Nov 19.
The research on preparing high-quality pellets by combining torrefaction and densification of biomass has received widespread attention. This paper investigated the influence of torrefaction temperature on biomass and evaluated the quality of three kinds of pellets (raw pellets, ex-situ torrefied densified pellets and in-situ torrefied densified pellets). When the torrefaction temperature was raised to 300 °C, the energy yield of rice straw (RS) and rice husk (RH) quickly decreased to 71.08% and 77.62%, and the cellulose was decomposed significantly. The results proved that 250 °C was an optimum temperature for RS and RH torrefaction. The densities of RS and RH in-situ torrefied densified pellets were 1236.84 kg/m and 1277.50 kg/m under 150 MPa, respectively. The density, Meyer hardness, hydrophobicity, and mechanical specific energy consumption of the pellet increased with the increase of molding pressure. The in-situ pellets had higher Meyer hardness, hydrophobicity, and lower mechanical specific energy consumption under the same molding pressure than raw pellets and ex-situ torrefied densified pellets. In addition, the bonding mechanism was studied by using scanning electron microscopy and ultraviolet auto-fluorescence. In-situ torrefaction and densification facilitated the formation of self-locking and the migration of lignin between particles. Compared with RH pellets, RS pellets had higher quality due to the higher hemicellulose content, which was necessary for forming stable hydrogen bonds.
将生物质的热解和致密化相结合来制备高质量颗粒的研究受到了广泛关注。本文研究了热解温度对生物质的影响，并评估了三种颗粒（生颗粒、异位热解致密化颗粒和原位热解致密化颗粒）的质量。当热解温度升高到 300°C 时，稻草（RS）和稻壳（RH）的能量产率迅速下降到 71.08%和 77.62%，纤维素明显分解。结果表明，250°C 是 RS 和 RH 热解的最佳温度。在 150MPa 下，RS 和 RH 原位热解致密化颗粒的密度分别为 1236.84kg/m 和 1277.50kg/m。颗粒的密度、Meyer 硬度、疏水性和机械比能耗随成型压力的增加而增加。在相同的成型压力下，原位颗粒的 Meyer 硬度、疏水性较低，机械比能耗较高，优于生颗粒和异位热解致密化颗粒。此外，通过扫描电子显微镜和紫外自动荧光研究了粘结机制。原位热解和致密化促进了自锁定的形成和颗粒间木质素的迁移。与 RH 颗粒相比，RS 颗粒由于含有更多的半纤维素，有利于形成稳定的氢键，因此具有更高的质量。
