The main purpose of this paper is to determine how the torrefaction influences the pelletabiliry of birch (hardwood) and spruce (softwood). Woods were torrefied at two different temperatures (225 and 275 °C) for 30 min. Energy loss (EL) and weight loss (WL), higher heating value (HHV), moisture uptake, water activity (a_w), and particle size distribution of raw and torrefied woods were determined to characterise the materials before pelleting and to see how torrefaction affects physical properties of wood. The impact of biomass type, temperature, and compacting pressure on pellet strength and compressibility of raw and torrefied wood was investigated using a single pellet press method. Pellets were produced at three different temperatures (60, 120, and 180 °C) and eight different compacting pressures (5, 10, 20, 40, 80, 160, 240, and 300 MPa). Torrefaction at 275 °C significantly increased tile HHV of both types of wood, in contrast to torrefaction at 225 °C. Compressing pressure and pelleting temperature had a significant positive impact on the material compressibility and strength. The strongest pellets were produced from raw spruce (68.62 ± 1.69 N/mm) and birch torrefied at 275 °C (86.34 ± 3.33 N/ mm). Compression strength and density of the pellets were strongly correlated following a power low trend (R~2 > 0.98). Torrefied material required higher force for pellet discharge because of the higher friction generated on the pelet surface—die area.
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机译：本文的主要目的是确定Torrefaction如何影响桦树（硬木）和云杉（软木）的颗粒物。树木在两个不同的温度（225和275°C）下渗出30分钟。测定能量损失（EL）和减肥（WL），更高的加热值（HHV），水分吸收，水活动（A_W）和粒子尺寸分布的原料和雾化树木的粒度分布，以表征在颗粒之前的材料，并看看如何烘焙影响木材的物理性质。采用单颗粒压榨法研究了生物质型，温度和压实对原料和雾化木材的颗粒强度和压缩性的影响。在三个不同的温度（60,120和180℃）和八个不同的压实压力（5,10,20,40,80,160,240和300MPa）中产生颗粒。 275°C的烘焙率显着增加了两种木材的瓷砖HHV，与225℃的烘焙相反。压缩压力和粒料温度对材料可压缩性和强度具有显着的正影响。最强的颗粒由原始云杉（68.62±1.69 n / mm）和275°C（86.34±3.33n / mm）的桦树粥样化。在功率低趋势（R〜2> 0.98）后，颗粒的压缩强度和密度强烈地相关（R〜2> 0.98）。由于在粘塞表面模具区域上产生的摩擦越高，雾化材料需要更高的颗粒放电力。
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