基于动力学与分形分析的絮凝控制新指标

Introduction of a new flocculation control factor based on kinetics and fractal dimension concept

摘要:

针对以速度梯度为核心的传统絮凝工艺动力学研究存在的理论与应用上的不足,通过对湍流水体中絮凝体的受力分析,表明在絮凝工艺中特征尺度量级的涡旋起重要作用,其离心惯性效应是絮凝体碰撞凝聚的动力学致因;通过对絮凝工艺的动力学传质过程影响因素的分析,利用数学分析方法,确定了絮凝体密度正比于水流的剪切强度;通过对絮凝体的形态分析,确定了絮凝体强度反比于水体剪切强度.进而提出一个基于动力学与形态学分析的新絮凝控制指标Fr0,完善了传统絮凝控制理论,可望为工程设计提供新方法.

Abstract:

Conventional flocculation kinetics based on velocity gradient law has several theoretical and applicable drawbacks.In this study,force analysis on flocs in turbulent flows was carried out and the results suggest that the vortex within characteristic scale is crucial in flocculation process,and the inertia effect of micro vortex causes the collision and aggregation of flocs.According to analysis of influenced factors on kinetic mass transfer and morphology of flocs,it is verified that the density of flocs is proportional to shear strength,whereas the strength of flocs presents inverse proportional correlation to shear strength.Furthermore,a new flocculation control factor defined as F r0is proposed based on kinetic and fractal morphology analysis.It is the modification of conventional flocculation control theory and provides a reference for practical design.