VOF modeling and experimental validation of ozonation reactive flow under high ozone concentration in three-phase reactors for environment protection

Abstract

In the realm of multiphase reaction engineering, the dynamic behavior of an ozonation bubble column reactor was comprehensively investigated under high ozone concentration (30–90g/Nm3) by means of a volume-of-fluid (VOF) model embedding the transport phenomena and the detoxification parameters. First, the CFD framework was validated in terms of hydrodynamic data to gather novel insights on the bubbly flow in three-phase reactors for environment protection. The numerical computations highlighted that both profiles for the bubble velocity, detachment time and diameter of ozone bubbles handled agreeably well with the experimental data. Second, the evolvement of bubble diameter when increasing the superficial gas/liquid velocity under different surface tension/viscosity conditions was investigated throughout various hydrodynamic flow regimes. According to the VOF simulation results, the detachment of ozone bubbles was more prominent at high interaction regimes when the bubble column was operated under high superficial liquid velocities, which correspondingly controlled the time-averaged bubble diameter. Afterwards, the VOF model was experimentally validated for the ozonation of phenol-like compounds under low and high interaction regimes reinforcing how the bubbly phenomena dictate the overall bubble column reactor performance. A heterogeneous distribution of ozone concentration has been found at the gas–liquid interface enlightening the competition between mass transfer and chemical reaction during the initial reaction time, which was most likely due to the unsteady phase holdup distributions and pollutant removal efficiencies.