柱状生物质颗粒与钢球颗粒在滚筒中的混合特性

Mixing characteristics in a rotary drum filled with cylindrical biomass and spherical steel particles

采用离散单元法DEM（discrete element method）对圆柱形生物质颗粒和钢球颗粒在滚筒中的混合进行了数值模拟,分析了滚筒转速和颗粒数量比对混合质量的影响。结果表明：在本文设定的工况下,颗粒的混合模式为阶梯模式,并且颗粒在混合时可以分成3个区域,即左面的单层钢球颗粒区、中间的钢球颗粒和生物质颗粒混合区、右面的生物质颗粒堆积区。左右两边的颗粒混合效果较差,中间的颗粒混合效果较好。当滚筒转速相同时,钢球颗粒和生物质颗粒数量比为3000∶200时的颗粒混合效果比钢球颗粒和生物质颗粒数量比为3000∶100时的好,即当钢球颗粒数量远大于生物质颗粒数量时,增加生物质颗粒的数量可以提高混合效果。在钢球颗粒和生物质颗粒数量比相同的情况下,当滚筒转速在5-25r/min的范围内,滚筒转速越高,颗粒的混合质量越好,并且颗粒混合达到稳定的时间就越短。

In this paper,mixing of cylindrical biomass particles and spherical steel particles in the drum was simulated with discrete element method（DEM）. The rotational speed and particles number ratio were changed in order to analyze the effect of rotational speed and particles number ratio to the particles mixing quality. The results showed that the motion mode was slumping in all six conditions. Particles mixing region was divided into three regions：the monolayer steel particles region in the left of the particles region, the mixing region of biomass particles and steel particles in the middle of the particles region and the accumulating region of biomass particles in the right of the particles region. The particles mixing quality in the middle of the particles region was far better than that in the left or in the right of the particles region. The mixing quality when the number ratio of steel particles and biomass particles was 3000∶200 was better than that when the number ratio of steel particles and biomass particles was 3000∶100 with stationary rotational speed,which means when the steel particles were far more than biomass particles. The increase of the number of biomass particles could enhance the mixing quality. When the rotational speed was changed from 5r/min to 25r/min,the higher the rotationalspeed,the better the particles mixing quality and the faster the mixing tended to be stable with stationary particles number ratio.