A Non-Wetting Packed Bed Gas Scrubber

Abstract

The operation of a small-scale packed column working under non-wetting condition was investigated to provide insight and design data for the subsequent development of a liquid metal irrigated packed bed gas scrubber. An 8 cm internal diameter Perspex column was used, packed with 9.5 mm polyethylene spheres and 10.0 mm glass spheres coated with paraffin wax. A counter-current air–water system was used. The packings well all essentially hydrophobic promoting a non-wetting water flow condition, simulating liquid metal flow on solid packings. Results on flow visualization, flooding capacity and liquid holdup trends, as well as the particulate removal performance of the non-wetting packed bed scrubber are presented in this paper. The maximum water droplet size on the non-wettable spherical packing surface could be estimated from the static equilibrium of a pendent droplet, governed by surface tension and gravitational force. The flooding capacity and liquid holdup trends of the water-irrigated packed column operating under non-wetting condition were found to be similar to those reported for liquid metal systems despite the pronounced differences in liquid density and surface tension. This suggests that the hydrodynamics of a packed column in non-wetting operation are largely influenced by the liquid–solid contact angle which overrides the dissimilarities in liquid physical properties. Good particulate removal performance was demonstrated by the non-wetting packed bed scrubber.