Experimental Investigation of Dust Deposit within Ceramic Filter Medium during Filtration-Cleaning Cycles

摘要

The penetration and deposit of particles within the medium is thought to be one reason that the residual pressure drop of the rigid ceramic filter increase with cycle number.In this study,the change in the microstructure of a single layer ceramic filter candle during filtration-cleaning cycle was observed by scanning electron microscope(SEM) and the resistance property of the filter was monitored accordingly.The experimental results show that there exists a serious dust deposit within the filter medium,especially at the surface region.This should be responsible for the decrease of the filter permeability.The deposit law of dust in the filter medium during filtration-cleaning cycle was then studied by measuring the deposit depth,the deposit amount,the particles distribution within the medium,the size distribution of deposited particles,and so on.Particles migration and fine particles penetration were found to be the main reasons,for which dust deposit within the filter medium became aggravated with cycle number.Based on a differential form of Ergun equation,an expression for the pressure drop of a used ceramic filter was developed with a good agreement with experimental results.Then,the effect of dust deposit on the residual pressure drop was studied at the different face velocities and dust sizes.It was found that face velocity and dust size significantly influence dust deposit within filter medium,and then the operation performance of the filter.