Microbubble-Dominated Mass Transfer Intensification in the Process of Ammonia-Based Flue Gas Desulfurization

There is immense potential for the industrial application of microbubble technology in the bubble column to intensify the multiphase flow mass transfer process. In this work, mass transfer characteristics (bubble size distribution, gas holdup, specific interfacial area, and volumetric mass transfer coefficient) were investigated systematically in a microbubble-dominated column. A key process of flue gas desulfurization, ammonium sulfite oxidation, was selected as the gas-liquid contact reaction. Experiments were performed in a laboratory scale (16 L) with four experimental variables including reaction temperature (293.15-333.15 K), ammonium sulfite concentration (0.04-0.31 mol/L), gas superficial velocity (0.0014-0.0142 m/s), and liquid superficial velocity (0.018-0.088 m/s). The bubble size was obtained by a high-speed photographic technique, and the volumetric mass transfer coefficient was measured by a chemical method. According to the experimental data, an empirical correlation for predicting the Sherwood number was proposed with good accuracy. Compared with the traditional bubble column, the microbubble system demonstrated excellent intensification ability of the mass transfer process in heterogeneous reactions. The results of this study can serve as a useful reference for the design and scale-up of industrialized efficient microbubble reactors.