Pressure characteristics in an airlift pump system

Airlift pumps (ALPs) are pump-based riser systems in which air is applied as a power source. They play an important role in the development of marine resources and the chemical industry. However, research detailing the frictional pressure drop gradient in ALPs is scarce. Therefore, this paper conducts experimental studies on the pressure characteristics within ALPs. The experiment was conducted in a vertical pipeline with a total length of 3.245 m and pipe diameter of 0.05 m. The experimental conditions included an air inlet, with a submergence ratio ranging from 0.6 to 0.815 and a gas superficial velocity ranging from 0 to 4 m/s. It was found that the frictional pressure drop gradient in ALPs exhibits a significant linear relationship with the gas void fraction. Additionally, the total pressure drop gradient has a linear relationship with the distance from the intake to the liquid surface. The frictional pressure drop gradient correlation established through these relationships can effectively predict experimental data for frictional pressure drop gradients under gas superficial velocities ranging from 0.5 to 4 m/s (where larger frictional pressure drop gradients are observed). The mean percentage error was 3.63%, while the mean absolute percentage error and root mean square percentage error were 8.92% and 11.05%, respectively. Finally, by analyzing pressure data from seven positions at different gas superficial velocities, it was discovered that in ALPs, pressure exhibits a significant linear relationship with height. Furthermore, this linear relationship remains remarkably consistent across various gas superficial velocities.