[Flocculation characteristics and mechanism of a conical fluidized-bed reactor]

Controlling parameters, flocculation efficiencies and flocs characteristics in a conical fluidized bed were studied, and the flocculation mechanism of this reactor was discussed. The results showed that the changes of the properties of packed particles, bed height and liquid superficial velocity would cause the changes of velocity gradient (G) and reaction time (T). The removal fraction (RF) of kaolin clay suspension increased with increasing of the value of GT, when the sediment time was 20 min. The RF was greatly affected by T, when G was within 169.2-189.7 s(-1). However, when G was less than 169 s(-1), it was so low that limited the collision among particles, which flattened increase of RF by increasing the T. It is the vortex caused by random movement of particles and vertically gradually decreased liquid superficial velocity in the conical fluidized bed that makes it applicable on flocculation. The flocs formed in the conical fluidized bed, were slightly larger in size and smaller in density than those in the mechanical mixing device, when close G and T were applied in two reactors. Better flocculation and sediment performance could be expected when the reactor and the reaction condition was improved.