Particle size distribution in a granular bed filter

Abstract

The effects of the filtering granule particle size and filtration superficial velocity on the dust particle size distribution in different layers of a granular bed system are discussed herein. A multilayer drawer granular bed filtration system was designed for these experiments based on filtering fly ash from a power plant. After a 1-h experiment, 47.8% of dust particles smaller than 2.5μm, 63.7% of dust particles smaller than 10μm, and 39.1% of dust particles larger than 10μm were captured by the granular bed (corresponding to initial volume fractions of 6%, 19.3%, and 80.7%, respectively). Large dust particles were more easily trapped by the granular bed than small dust particles. Increasing the size of the filter granules and increasing the superficial velocity of the inlet flue gas were both effective ways to enhance the dust-holding capacity of the granular media throughout the granular bed.