However, lignite belongs to viscous particles. The agglomerative
phenomenon of lignite is a serious problem using fluidized
bed dryer. To enhance the fluidization quality of lignite, additional
field assisted fluidized bed was investigated such as magnetic field,
vibration, agitation, and acoustic field. It is well known that the
application of an acoustic field can improve the fluidization quality
of Geldart C particles [6,7] and Geldart A particles [8,9]. The results
of David RE et al. [10,11] showed that high frequency (sound) vibrations
could decrease the minimum fluidization velocity and