The effect of pulsating air injection on the development of two-phase flow instabilities in an airlift pump

Airlift Pumps with Annulus Risers: An Experimental Investigation

“…4a and 4b show the lifted liquid flow rate and efficiency for both circular and annulus risers, respectively. Note that the pumping efficiency of the airlift pump has been calculated using the modified version of Nicklin equation that considers the dual injection method [12], as follows:…”

“…Experimental observations revealed the presence of two two-phase flow patterns including slug and churn flow within both risers under the studied test conditions. Flow patterns were identified by both flow visualization and instantaneous void fraction measurements, both at Z/D=30, where two-phase flow within the riser reaches quasi-developed region [12]. The PDF diagrams of the measured void fraction data have been shown in Figs.…”

“…According to the literature, the performance curve of airlift pumps is a function gas flow rate and pressure as well as submergence ratio and riser length and diameter [2], [10], [11]. In fact, lifted ICMFHT 109-2 liquid flow rate increases with increasing injected gas flow rate and reaches a maximum value (slug-churn transition), is followed by a slight decrease and then, remains nearly unchanged (churn and annular regimes) [2], [12], [13]. However, with increasing gas flow rate, the pump efficiency increases first to a maximum point and then, drastically declines [2].…”

“…Larger submergence ratios contribute to a better performance, i.e., increased liquid flow rate, due to the higher static pressure of the liquid column in the riser [2], [3], [11], [13][14][15][16][17]. Also, increasing submergence ratio has been found to reduce the minimum gas flow rate needed to lift the liquid phase [2], [12]. Also, Kassab et al [2] found that increasing riser length (static lift) at constant submergence ratio can lead to slight improvement in the pump performance.…”