超细片状颗粒流态化特性研究

Fluidization behavior of flaky ultra-fine particles

分别以粒径相近的超细球形铝粉、片状铝粉、片状云母粉为原料,采用床层膨胀和床层塌落法对其流态化特性进行了研究。结果表明,3种颗粒在流化床中流化的难易程度不同,其中片状铝粉的起始流化速度为0.087 m/s,平衡压降约为3.6 kPa,最大床层膨胀率为1.36;片状云母粉的起始流化速度为0.079 m/s,平衡压降约为4.2 kPa,最大床层膨胀率为1.60;球形铝粉的起始流化速度为0.063 m/s,平衡压降约为5.8 kPa,最大床层膨胀率为1.71;片状铝粉和片状云母粉的起始流化速度高、床层膨胀率低、平衡压降低、滞气性能差,比球形铝粉更难于流化。另外,对处于流化状态时的片状铝粉床层在不同气速下平衡压降随时间的波动情况进行了考察,并测绘了压降波动曲线,结果表明其压降波动幅度约为5%。

Fluidization behaviors of ultra - fine spherical aluminum, flaky aluminum and flaky mica particles with approximate average diameter were studied through methods of bed expansion and pressure drop as well as bed collapse. The results showed that the incipient fluidization velocity of flaky aluminum, flaky mica and spherical aluminum was 0. 087, 0. 079 and 0. 063 m/s, respectively; their respective maximum bed expansion rate were 1.36,1.60 and 1.71 ; their respective equilibrious pressure drop were 3.6,4.6 and 5.8 kPa. The flaky particles had higher incipient fluidization velocity,lower bed expansion rate and pressure drop,weaker gas - retarded and were more difficult to fluidized than spherical aluminm powder. In addition,the time dependence of fluctuation of bed pressure drop at different gas velocity was investigated for the fluidized flaky aluminum particles, their relationship was illustrated, and approximately 5% pressure drop flucluation could be seen.