Measurement of gas holdup profiles in a gas liquid cocurrent bubble column using electrical resistance tomography

Radial variation of the gas holdup and mean holdups were investigated in a 0.160 m i.d. bubble column using electrical resistance tomography with two axial locations (Plane 1 and Plane 2). In all the experiments tap water was used the liquid phase and air was the gas phase. Superficial gas velocity was varied from 0.02 to 0.25 m/s, and superficial liquid velocity varied from 0 to 0.011 m/s. The effect of liquid velocity on the mean holdups and radial gas holdup distribution was discussed. The experimental results showed the liquid velocity slightly influence the mean holdup and radial hold-ups distribution in the operating condition, and the liquid flow can improve the transition gas velocity for the homogeneous regime to heterogeneous regime. Meanwhile the mean gas holdups as a function of gas velocity were derived from using differential pressure method and electrical resistance tomography method. The agreement between results obtained by these two methods is generally very good in the homogeneous regime. But in the transition regime and heterogeneous regime, results with ERT are slightly larger than one with the differential pressure method. According to the experimental results, a correlation for the centreline holdup is obtained.