Enhancement of gas holdup and oxygen transfer was investigated in the riser of a three-phase circulating fluidized bed, with a diameter of 0.102 m (ID) and a height of 3.5 m, by means of liquid swirling flow. Effects of gas (0.01-0.07 m/s) and liquid (0.17-0.44 m/s) velocities, fluidized solid particle size (1.0, 1.7, 2.1, 3.0 mm), solid circulation rate (2-8 kg/(m 2 s)) and swirling liquid ratio (0-0.5) on the gas holdup and volumetric oxygen transfer coefficient in the riser were examined. The gas holdup and oxygen transfer coefficient could be increased up to 25-30% and 20-25% respectively, by means of liquid swirling flow in the riser. The values of gas holdup and volumetric oxygen transfer coefficients were well correlated in terms of dimensionless groups as well as operation variables within these experimental conditions.

Flow properties of gas phase reactants such as size, rising velocity and frequency were investigated in simulated three-phase slurry bubble column reactors. Effects of gas velocity, reactor pressure, liquid viscosity, solid content in the slurry phase and column diameter on the flow properties of a gas reactant were determined. The multiple effects of operating variables on the bubble properties were well visualized by means of contour maps. The effects of operating variables on the flow properties of bubbles changed with changing column diameter of the reactor. The size, rising velocity and frequency of reactant gas bubbles were well correlated in terms of operating variables including column diameter of the reactor.

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