Experimental study and optimization on filtration and fluid flow performance of a granular bed filter

Abstract

An experimental system for a fixed granular bed filter (GBF) used to filter dust particles in industrial flue gas was built. The effects of filtration superficial velocity, bed height, and granules size on filtration and fluid flow performance were investigated. The results demonstrate that the GBF has high filtration efficiency and relatively low pressure drop, e.g. the filtration efficiency can reach 99.45% with a pressure drop of 291 Pa. The increase of filtration superficial velocity leads to the decrease of filtration efficiency but the increase of pressure drop. The filtration superficial velocity lower than 0.6 m/s is recommended to achieve higher filtration efficiency, lower pressure drop and acceptable filtration rate in the studied geometric parameter range (granule size: 3–10 mm, bed height: 30–120 mm). The increase of bed height and the decrease of granules size are beneficial to increase filtration efficiency, but detrimental to reduce the pressure drop. In addition, the effects of granules size on pressure drop are more significant than that on filtration efficiency. Based on the experimental results, the structural optimization was performed for the fixed GBF and an optimized structure with different granules sizes was designed. The validation results indicate that the designed GBF structure has excellent filtration and fluid flow performance compared with the traditional structure with single granules size. Under the investigated filtration superficial velocity region, the average filtration efficiency is enhanced 3.23% and the pressure drop is reduced 49.94%.