Parameter study of filtration characteristics of granular filters for hot gas clean-up.

Granular filters are a promising technology in hot gas clean-up for coal-based power generation systems. Numerical simulations are presented for the filtration characteristics of randomly packed granular filters. The effect of filter height is first investigated to obtain a unit height which can predict filtration characteristics of the entire filter, and it is found that the unit height should be at least 10 times the granule diameter. The filtration performance, including filtration efficiency, pressure drop and deposition uniformity are analyzed, and the effect of gas velocity, particle diameter and granule diameter are then investigated. The results show that the pressure drop increases rapidly with the increase of gas velocity and decrease with granule diameter. Increasing the gas velocity and particle diameter leads to increased filtration efficiency and decreased deposition uniformity. The effect of Stokes number on filtration efficiency and deposition uniformity can be divided into three regimes, and filter height and granule diameter need to be optimized according to Stokes number. A correlation of initial filtration efficiency is obtained for use in filter design and structural optimization. Unlabelled Image • Filtration characteristics of randomly packed granular filters are investigated. • A unit filter height is obtained, which can predict filtration performance of the entire filter. • An index is introduced to evaluate the deposition uniformity along the filter. • Effects of each factor on pressure drop, efficiency and deposition uniformity are studied. • A correlation of efficiency is obtained for use in filter design and structural optimization. [ABSTRACT FROM AUTHOR]