慢速热解对生物质粉体物性的影响

慢速热解方法可以有效地脱除生物质中的氧元素,提高生物质的能量密度,从而提高生物质气流床气化合成气的热值;并可以有效地改善生物质的物性,实现稳定连续的输送。使用直剪仪对不同粒径的生物质和不同热解温度的半焦进行物性分析,结果表明:热解后,半焦的休止角、内摩擦角和开放屈服强度都明显降低;堆积密度比原料的堆积密度大;从电镜图片分析得出表面结构的变化是物性发生变化的根本原因;400℃半焦的休止角为38.8°,堆积密度为269.4 kg/m3,开发屈服强度为26.8 kPa,并结合半焦气化合成气的热值得出400℃半焦作为气化原料比较合理。

Influence of slow pyrolysis on physical properties of biomass powders

Slow pyrolysis removes effectively oxygen from biomass and improves the energy density of biomass.So it increases the heat value of biosyngas in biomass entrained-flow gasification.Meantime,it changes the physical properties of biomass powders.The physical properties of different particlesized biomass and different pyrolysis temperature of semi-coke were analyzed by using direct shear cell.The results show that the angle of repose,the angle of internal friction and unconfined yield strength of semi-coke decrease obviously;the bulk density of semi-coke is bigger than that of biomass;the essential reason of these variations is the change of surface structure from SEM;the angle of repose,the bulk density and unconfined yield strength of semi-coke is 38.8°,269.4 kg/m3 and 26.8 kPa,respectively.The semi-coke at 400 ℃ is reasonable for biomass entrained-flow gasification as raw material.