Gas-liquid dispersion in a hot-sparged gas-liquid-solid stirred tank

Gas-liquid-solid three-phase stirred tanks/reactors are widely used in many processes, however very few studies have been conducted on the effect of solid particle characteristics on the solid-liquid suspension and gas-liquid dispersion. An experimental system involving a hot-sparged three-phase tank with diameter 0.476 m (T) agitated by a hollow blade dispersing turbine (HEDT) at the top and a wide blade hydrofoil up-pumping impeller (WHU) at the bottom, in which air, deionized water and glass beads are used as gas, liquid and solid phase respectively, has been constructed. The power consumption and gas hold-up of the system were measured with aid of a torque transducer and a calibrated radar probe. The results show that the relative power demand (RPD) in the hot-sparged system is much higher than that in the cold system. The amount of solid has a negligible effect on the power demand in the hot-sparged system and a similar result is obtained for the cold-gassed system. The gas hold-up in the hot-sparged system is up to 50% less than that in the cold system, and the difference between the two systems decreases with increasing amount of solid. The gas holdup increases with increasing amount of solid in the hot-sparged system, although there is no effect on the gas holdup in the cold system. The results obtained are of value in the design of hot-sparged gas-liquid-solid multi-impeller reactors.