Effect of Step Geometry on the Performance of the Airlift Pump

Airlift pumps are devices which are widely used in industrial applications. Parameters such as diameter of the pipe, tapering angle of the upriser pipe, submergence ratio, the gas flow rate, bubble diameter, and inlet gas pressure affect the performance of this type of pumps. In this research, the performances of airlift pumps with a vertical upriser length of 9 1 4 mm and initial diameters of 6 and 8 mm and various heights for steps, range 0 : 2 to 0 : 9 m, in submergence ratio of 0 : 6 are investigated numerically. The results show the improvement in the performance of step airlift pump (SALP) in comparison with ordinary type (OALP). Considering the effect of height of steps and secondary pipe diameter, can be shown that in constant gas flow rate there exist specific height and secondary diameter for step which can optimize the performance of the pump. The numerical results were compared with the existing experimental data, showing a reasonable agreement. The results have indicated that step airlift pump has higher efficiency than the pump with constant pipe diameter.