Effect of Bubble Size and Angle of Tapering Upriser Pipe on the Performance of Airlift Pumps

Airlift pumps are devices with the ability to lift liquid phase by injecting the gas phase. Parameters that affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe, and the submergence ratio, which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters such as the gas flow rate, bubble diameter, bubble distribution, and inlet gas pressure. In this research, the performance of an airlift pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe. For this purpose, an airlift pump with a riser length of 914mm and different diameters (6, 8, and 10mm) and seven tapering angles (0 degrees, 0.25 degrees, 0.5 degrees, 1 degrees, 1.5 degrees, 2 degrees, and 3 degrees) is numerically modeled and analyzed. Different submergence ratios are used: 0.4, 0.6, and 0.8. The numerical results are compared with the existing experimental data in the literature and show reasonable agreement. The results indicate that decrease in size of the bubble diameter increases mass flow rate of liquid at constant submergence ratios. The present study reports the improved performance of this pump with decrease in bubble size and increase in angle of tapering upriser pipe. Moreover, the results show that the tapering upriser pipe with 3 degrees tapering angle gives the highest efficiency at nearly all submergence ratios. Further, the highest efficiency of the pump is shown to be at the largest submergence ratio.