流化床混凝装置中多级速度梯度的建立及其对混凝反应的影响

利用不同性质颗粒在流化状态下可实现自然水力分级的特征，在流化床反应器中沿水流方向实现了多级速度梯度的建立。在研究流化床混凝反应器的混凝动力学特征基础上，探讨了以800 μm和1 200 μm树脂颗粒为固相的多级速度梯度流化床（MGF）的速度梯度分布特征、混凝效率和絮体形态特征，并与以1 200 μm树脂颗粒为固相的单级速度梯度流化床（SGF）进行了对比研究。结果表明：与单级速度梯度相比，多级速度梯度可为胶体或微颗粒的高效碰撞和絮体再增长创造更适宜的环境，有助于形成尺寸更大、密度更大的絮体，提高了絮体的可沉降性；MGF在处理人工配置的高岭土悬浊液和分散红染料废水时，混凝效率比SGF分别提高了2%～4%和7%～20%。

Set-Up Method of Multi-Velocity Gradient in a Fluidized Flocculation Bed and Characterization of Its Impact on Flocculation Reaction

Multi-velocity gradients along the up-flow direction was develped in a fluidized bed reactor based on the fact that different heavy solid particles could achieve a hydraulic classification under fluidized condition. Based on the results of the flocculation kinetic characteristics of fluidized bed flocculator, the characteristics of a multi-velocity gradient fluidized bed flocculator (MGF) filled with 800 μm and 1 200 μm resin particles was studied in the gradient distribution characteristics, flocculation efficiency and morphological characteristics of the flocs. The results obtained in the MGF were compared with a single-velocity gradient fluidized bed flocculator (SGF) filled with 1 200 μm resin particles directly. It was found that the environment for collision of colloids or fine particles was more suitable for the MGF, and thus the continuous growing of the clusters could be created. As a result, bigger and denser flocs could be formatted in MGF, and then the sedimentation ability of the flocs improved obviously which also confirmed by the improved flocculation efficiencies. The flocculation efficiency of kaolin suspensions and dispersed red increased 2%-4% and 7%-20% respectively in the MGF compared with the SGF.