Airlift pumps are used in many industries. In these pumps, the performance is strongly affected by the geometrical design conditions. In this study, the performance of an airlift pump is experimentally evaluated for both circular and annulus pump risers. An airlift pump operating under air-water two-phase flow conditions was tested using a dual pump injector and for a constant submergence ratio. Capacitance sensors are used to measure the instantaneous void fraction through the pump riser, while high-speed images are analyzed to identify the interfacial structures of the air-water two-phase flow patterns through the pump risers. The results show that the water flow rate and efficiency of the pump for both risers are strongly dependent on the flow-pattern. In the annulus riser, higher liquid flow rates and pump efficiency are achieved at low gas flow rates, where slug pattern exists, while for the circular riser, the pump performs better at higher gas flow rates. Also, void fraction was found to be higher in the annulus riser for the entire range of gas flow rate due to the smaller cross-sectional area and the faster gas phase velocity through this area. Moreover, in the annulus riser, the Taylor bubble exhibited rotational motion around the pipe axis while moving upward. The length of Taylor bubbles in the pump riser was found to be longer and move with higher velocity and frequency in the case of the annulus riser, which is contributing to the better pump performance at low air flow rates.
One of the most important criteria in determining the performance of airlift pumps is to determine the two-phase flow characteristics in the pump riser. These include the determining the average void fraction and both the slug velocity and frequency of the two-phase flow in the vertical pipe. In the current work, three image processing methods were examined to describe the two-phase hydrodynamic parameters as they relate to the pump performance. Experiments were carried out using Xanthan Gum-water solutions with varying XG concentrations between 0.05-0.25 wt% in a pump riser of 31.75 mm in diameter. High-speed camera with 3000 f/s capabilities was used to obtain the flow visualisation images for the two-phase flow distribution downstream of the pump injector. The preliminary results suggested that the image processing technique using background subtraction algorithm can be an effective approach in evaluating the flow structure and consequently can be used to determine void fraction and slug characteristics.
Experiments are performed in a recirculating two-phase flow loop using an airlift pump with an axial air injector and at different non-Newtonian rheological behaviours. This was achieved using three mixtures of Xanthan Gum (XG) and water of 0.05 %, 0.15 %, and 0.25 % by weight concentrations. Both air and liquid flow rates are recorded for the desire pump operating conditions. The pump performance found to be directly correlated with the concentrations of XG. The pump flow rates decreased as the XG concentration increased due to the decrease of slug velocity which is responsible for high lifting effect. The recorded slug velocity was found to change between 1.81 cm/s, 1.75 cm/s, and 1.7 cm/s for XG concentrations of 0.05 %, 0.15 %, and 0.25 % respectively. Also, with the increase of XG concentration, the slug length found to increase due to the formation of large slugs without many trailing small bubbles as seen in the lower concentrations' cases. As the viscosity increased for different XG concentrations, the calculated efficiency of the airlift pump found to decrease as well. This is attributed to the fact that as the liquid became more viscous, higher energy of the air is required to overcome the shear stresses acting on the liquid phase to provide lifting.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.