In this work, Norway spruce stem wood, stump and bark were torrefied in a bench scale tubular reactor at 225, 275 and 300 °C with two residence times (30 and 60 min). Effect of torrefaction on general properties, chemical composition, grindability and microstructure and morphology of biomass samples were studied. An increase in heating value and fixed carbon content of the torrefied biomass was observed for increasing torrefaction temperature and residence time. Chemical compositions of torrefied biomass samples considerably changed with increase of torrefaction severity. For the stem wood and stump, the relative hemicellulose content significantly decreased from respectively 42.3% and 29.8% to less than 1% after torrefaction at 300 °C for 60 min. The hemicellulose content of untreated bark decreased from 27.5% to 0.14% after torrefaction at the same conditions. Additionally, the cellulose content of the torrefied bark drastically decreased already to half the initial value at a torrefaction temperature of 275 °C, with only trace amounts left in the 300 °C torrefied products. The grindability of stem wood and stump were substantially improved after torrefaction treatment. The energy required for grinding stem wood and stump torrefied at 225 °C decreased to respectively 87 and 70 kWh/ton, which are less than 50% of the energy needed for grinding the untreated samples. For raw bark, much less grinding energy is required compared to those for raw stem wood and stump, and torrefaction has minor effects on the grindability of bark. The ground torrefied biomass samples have much smaller particles than those of the untreated ones. SEM analysis results show that particles from ground torrefied samples lose their fibrous structure with decrease of length-to-diameter ratios, compared to untreated biomass samples. It explains the shift in particle size distribution curves towards smaller particles as obtained from the sieving tests.

在这项工作中，将挪威云杉的茎干木材，树桩和树皮在台式规模的管式反应器中于225、275和300°C焙干，停留时间分别为30和60分钟。研究了焙烧对生物质样品的一般性能，化学成分，可磨性以及微观结构和形态的影响。观察到烘焙后的生物质的热值和固定碳含量增加，从而提高了烘焙温度和停留时间。烘焙生物质样品的化学成分会随着烘焙强度的增加而发生很大变化。对于茎木和树桩，在300°C烘烤60分钟后，相对半纤维素含量分别从42.3％和29.8％显着降低至不足1％。未经处理的树皮的半纤维素含量从27.5％降至0。在相同条件下烘焙后为14％。此外，在275°C的烘烤温度下，烘烤过的树皮中的纤维素含量已经急剧下降至初始值的一半，而在300°C的烘烤过的产品中仅残留了少量的纤维素。经过烘烤处理后，茎木和树桩的可磨性得到了显着改善。在225°C下研磨茎木和残端的树桩所需的能量分别降低至87和70 kWh /吨，不到研磨未处理样品所需能量的50％。与未加工的茎木和树桩相比，未加工的树皮所需的磨削能量要少得多，而焙干对树皮的可磨性影响较小。磨碎的生物质样品的颗粒比未处理的样品小得多。SEM分析结果表明，与未经处理的生物质样品相比，磨碎的焙烧样品中的颗粒失去了纤维结构，长径比降低。它解释了从筛分试验获得的粒度分布曲线向较小颗粒的移动。