Hydrodynamic and heat transfer investigations conducted in a bubble column with fine powders and a viscous liquid

Abstract

Experimental investigations of gas holdup and heat transfer have been conducted in semi-batch mode in a 0.108 m diameter bubble column, equipped with either one of three single axial heat transfer probes with diameters 19.0, 31.8 or 50.8 mm, or with a bundle of seven 19 mm tubes in an equilateral triangular configuration which has a pitch of 36.5 mm. Therminol® 66, fine red iron oxide powder (1.7 μm) and nitrogen were used as the liquid, solid and gas components respectively. The solid concentration was varied up to 50 wt.%. Nitrogen holdup, and heat transfer coefficient for the heated probe test section to the surrounding two- and three-phase dispersions were measured at ambient temperature and pressure as a function of nitrogen velocity. These experimental data were used to establish the influence of nitrogen velocity, solids concentration and internals configuration on these two properties. In addition, gas holdup data were used to evaluate correlations due to Reilly et al., Smith et al., Roy et al. and O'Dowd et al.; similarly, the heat transfer data were used to evaluate the correlations of Deckwer, Suh and Deckwer, Kim et al., and Pandit and Joshi. A semi-empirical correlation for h w is proposed.