终端过滤与重力沉降相似性研究

STUDY ON COMPARABILITY OF DEAD-END FILTRATION AND GRAVITY SEDIMENTATION

通过静态重力沉降实验、静态终端过滤实验及搅拌终端过滤实验,对比研究了终端过滤与重力沉降过程的规律,从固液两相的运动特征、各分界面的变化曲线分析了二者的相似性。实验结果表明,在沉积层和滤饼上方,液相相对于固体颗粒的运动方向相同,且始终向上,使得两过程中固体颗粒的受力情况相似。在沉积层和滤饼内,由于液相运动方向不同,使得颗粒受到的剪切力方向正相反。重力沉降与静态终端过滤的沉降曲线均符合H=He+(H0-He)e-t/t1的形式。在过滤压差Δp≠0的静态终端过滤中,固体颗粒的沉降过程可以看作是颗粒在加速度为Cg(C>0)条件下的"重力"沉降。由此,为建立终端过滤与重力沉降统一性模型奠定了实验基础。

According to the movement rules of the two phases of solid particles and liquid,the air-clear and clear-suspension interface in the characteristic of dead-end filtration and gravity sedimentation process,their comparability and related rules were studied for founding a mathematic equation to describe the two different processes.The experimentation includes gravity sedimentation,dead-end filtration with sedimentation and dead-end filtration without sedimentation.In the two processes,the relati ve movement between liquid and solid particles is always in the same direction above the sediment and cake.And the forces of solid particles suffered are similar.But in the sediment and cake,the liquid moves in different direction.So the shear stresses of particles suffered are in an opposite direction.The curves of clear-suspension interface height vs time in both processes accord with the same function:H=H_e+(H_0-H_e)e^-t/t_1.In dead-end filtration with sedimentation,the settling process of particles can be regarded as 'gravity'settling,where the acceleration equals Cg(C>0).