Steam Stripping of Bromine from Sea Brine: Mass-Transfer Analysis of Randomly Packed Columns

Abstract

Mass transfer data have been collected on stripping of bromine from aqueous solution at different flow rates of liquid and steam using Rasching and Pall Ring packings randomly packed in glass columns (6.25 to 90 cm diameter) and tower constructed by using granite slabs having square cross-section (25 cm × 25 cm). In the present study, the model proposed by Wagner et al. [1] for distillation considering gas phase resistance as the controlling resistance is modified wherein liquid phase resistance is considered as the controlling resistance for mass-transfer. The modified model and model proposed by Castillo et al. [2] for stripping of volatile organic compounds (VOCs) from water have been successfully applied to the experimental data on debromination of sea brine. Average deviation between observed and calculated value of height of transfer unit based on the modified model of Wagner et al. [1] is 20.9 and 10.7% for bromide-bromate solution and bittern, respectively. The average deviation between observed and calculated overall volumetric liquid phase mass transfer coefficient is 16.62, 15.13 and 84.19% for debromination of bittern using pilot plant data, commercial bromine plants, and sodium bromide-bromate solution, respectively, based on correlations given by Wagner et al. [1]. Similar results based on Castillo et al. [2] model are 34.43, 49.69 and 26.80%, respectively. Volumetric liquid phase mass transfer coefficient for stripping of VOCs from water is in the range of 0.001-0.008 (1/s) whereas in the present study it varies from 0.001 to 0.017 (1/s). In other words, steam stripping of bromine from aqueous systems appears comparatively easier than stripping of VOCs from water.