Flow characteristics of countercurrent bubble column with perforated draft tube

In order to improve the performance of the bubble column, the countercurrent bubble column with perforated draft tube was considered, and the flow characteristics were experimentally examined. A part of gas and liquid radially flowed through the holes of the draft tube and large bubbles were subdivided into small ones. The gas holdup and volumetric coefficient showed a maximum with respect to the draft tube diameter, and increased with increasing draft tube length. The ratios of the gas holdup and volumetric coefficient of the column with perforated draft tube to those of the column without draft tube increased with increasing liquid downflow velocity and decreasing gas velocity. The countercurrent bubble column with perforated draft tube was found to be effective in increasing the gas holdup and volumetric coefficient for the viscous liquid.