Abstract: Fluidization behavior of three kinds of SiO2 powder with different sizes and influence of acoustic field were investigated in a 56 mm i.d. glass tube fluidized bed. The average diameters of the three kinds of powder were 5~10 nm (sample 1#), 0.5 mm (sample 2#) and 10 mm (sample 3#), respectively. The particles of samples 1# and 2# could form stable agglomerates under high gas velocity, thus the cohesive force of unit mass was decreased and stable fluidization achieved. However, no stable agglomerates were observed during fluidization of 3# particle sample, which was never fluidized stably. Sound wave could improve the fluidization behavior within a given range of sound frequencies (40~60 Hz) for all the three kinds of powder. The sizes of agglomerates decreased and the minimum fluidization velocities reduced with increasing sound pressure level for 1# and 2# particle samples. Whereas 3# particle sample could never be fluidized smoothly even under sound energy action.

Key words: ultrafine particle, acoustic field, fluidization, agglomerate

摘要： 采用内径为56 mm的玻璃管流化床，考察了平均粒径分别为5~10 nm(1#), 0.5 mm(2#)及10 mm(3#)的SiO2超细颗粒在无声场及声场存在下的流化行为. 无声场时，1#和2#颗粒可在较高的气速下形成稳定聚团，单位质量颗粒团间作用力与原生颗粒相比显著下降，因而可实现稳定的聚团流化，3#颗粒因颗粒间粘性力较大，无法实现稳定流化. 40~60 Hz的声场对3种超细颗粒的流化行为均可起到一定的改善作用，在此频率范围外，声场的作用不明显. 提高声压级，可以使1#和2#颗粒团发生一定程度的破碎，聚团尺寸减小，最小流化速度降低. 在实验范围内，添加声场无法使3#颗粒实现稳定流化.

关键词: 超细颗粒, 声场, 流化, 颗粒团