Gas holdup and annulus liquid circulation velocity in a draft tube gas-liquid-solid spouted vessel

In a draft tube gas-liquid-solid spouted vessel, the average gas holdups and annulus liquid circulation velocities were measured over a wide range of operating conditions, and the flow patterns were observed. The hydrodynamic characteristics obtained for the gas-liquid-solid three phase system were also compared with those for the gas-liquid two-phase system. For low gas and liquid flow rates, gas holdups were strongly affected by the solid particles, and the gas holdups in the gas-liquid-solid three -phase system were always higher than those in the gas-liquid two-phase system. Experimental equations were also proposed to express the gas holdups in the whole range of gas and liquid flow rates. Annulus liquid circulation velocities obtained for the low liquid flow rate were greatly reduced by the solid particle beds on the bottom of a column. However, after all solid particles began to circulate in the column, the behaviors of annulus circulation velocities were found to be very similar to those in a draft tube gas-liquid spouted vessel.