The experimental work was conducted in a plexiglass column of 140 mm ID packed with glass beads of different diameters(1.9

3.6

5.2 and 9.3 mm)by using air and water as the working system after the column was preflooded with high gas and high liquid flow rates to ensure complete wetting of the bed.The data acquisition of liquid holdup and pressure drop hysteresis loops was made possible by installation of pressure transducers and electrical capacitance tomography(ECT).The proportions of film flow

cluster zone and gas zone were obtained by analyzing the experiment data in different operation conditions using the parallel zone model.It was found that the proportion of single gas or cluster zone was much smaller than that of the gasliquid zone when gas and liquid flow rates were high.The proportion of gas zone decreased instead of increasing when gas flow rate increased.But the proportion of gasliquid zone increased.It indicated that there was strong interaction between liquid and gas.In gasliquid zone

gas flow rate was greater than liquid flow rate.Meanwhile

gas flow rate was always close to superficial gas velocity.