Airlift Pump Research Articles

Evaluate the performance of the vertically upward gas–liquid two-phase flow in an airlift pump system

This paper conducts experiments on gas–liquid two-phase flow in airlift pumps (ALPs) using air–water as the medium, measuring liquid flow rates over a broad range of flow rates, and investigates the effects of submergence ratio and the two-phase pipe section length on the performance of ALPs. Evaluate the performance of ALPs under specified operating conditions. Experimental results show that liquid flow velocity initially increases with the increase in gas flow velocity and then stabilizes; the highest liquid flow velocity does not necessarily correspond to the highest efficiency. The performance of the ALPs increases with the two-phase pipe section length within a certain range of the two-phase pipe section length. However, once this range is exceeded, the performance of the ALPs is nearly unaffected by the two-phase pipe section length; the minimum gas flow velocity required to pump liquid increases as the submergence ratio decreases. This paper presents ALPs model that is independent of pipe diameter and flow range and validates it against experimental results. The model outcomes align well with the experimental data across all flow ranges. Additionally, the model effectively captures the sensitivity changes related to the two-phase pipe section length and the submergence ratio, and accurately predicts the minimum gas flow velocity required for liquid discharge under various operating conditions.

Frictional pressure drop of the vertically upward gas–liquid two-phase flow in an airlift pump system

Airlift pumps (ALPs) are promising in the oil and chemical industry, owing to their advantages such as a simple structure, convenient operation, wide applicability, high cost-effectiveness, environmental friendliness, safety, and reliability. However, there are few studies on the frictional pressure drop of vertically upward gas–liquid two-phase flow in ALPs. Therefore, this study presents an experimental investigation of the frictional pressure drop in the vertically upward gas–liquid two-phase flow in ALPs. Experiments were conducted in a vertical pipe with a total length of 3.245 m and a two-phase section of 2.8 m; the working pressure of the air compressor was 0.4 MPa, pipe diameter was 0.05 m, submergence ratio ranged from 0.6 to 0.85, and gas superficial velocity ranged from 0 to 4 m/s. A total of 74 sets of experimental data were obtained, and the frictional pressure drop models of 36 classical gas–liquid two-phase flows were evaluated. The results indicated that classical gas–liquid two-phase flow models significantly underestimated the experimental results. By analyzing the experimental data, visualizing the internal flow field, and performing theoretical derivations, a new frictional pressure drop correlation was established for the vertically upward gas–liquid two-phase flow in ALPs. The results demonstrated that the new model could accurately predict the frictional pressure drop of ALPs with mean percentage error, mean absolute percentage error, and root mean square percentage error values of 7.8%, 12.18%, and 25.86%, respectively.

Experimental Investigation on the Effect of Nozzle Design on Airlift Pump Performance

Experimental Investigation on the Effect of Nozzle Design on Airlift Pump Performance

Experimental Investigation of Film Thickness in Wastewater Airlift Pumps by an Image Processing Method

The airlift pump is a key part of wastewater treatment and is employed as an innovative and feasible collection tool. However, as one of the key factors in the lifting capability of airlift pumps, film thickness in the gas–liquid two-phase flow operating in pumps is still an unknown topic because it is difficult to measure. This paper proposes a visualization method for measuring film thickness and investigates the film thickness when operating under gas flow with a high rate in airlift pumps using experiments. Firstly, a simulation experiment platform was built, and the images of the film structure were acquired by a high-speed camera. Then, image-processing technology and an image distortion correction were proposed to extract the gas–liquid interface for studying the thickness of the film. The experimental results demonstrated that a large film thickness ranging from 0.15 D to 0.24 D was found in airlift pumps and that its film thickness kept a constant value, even under a high gas superficial velocity, maintaining a large output liquid flow from airlift pumps. As wastewater was carried by wastewater treatment, a larger film thickness of the annular film will benefit the high lifting rate of wastewater. The works in this paper offer valuable insights for the higher performance of working airlift pumps and wastewater treatment efficiency.

Detailed 3D URANS analysis of two-phase flow in an airlift pump

An airlift pump is a vertical tube that utilizes the buoyant effects of a gas to lift a liquid. Unlike a standard mechanical pump, the liquid flow rate through the airlift pump is not directly controlled; rather, it depends on the supplied gas flow rate, the tube length and diameter, and the relative height of the liquid supply free surface (submergence ratio). The present study uses the commercial CFD code ANSYS CFX to model the isothermal, 3D, transient flow in an airlift pump using water and air. The model applies pressure boundary conditions at both ends of the tube and specifies the mass flow rate of air through multiple openings in the side of the tube. The bottom of the tube is an inlet of water only and the outlet is a two-phase flow opening. A time-dependent, homogeneous, VOF two-phase RANS CFD modelling approach is used with the air treated as an ideal gas. This work found that a complete 3D domain was necessary for consistent prediction of the airlift performance and physically realistic two-phase flow structures. Statistical analysis of the two-phase flow structures was applied to characterize airlift pump instability and better understand the physics of the airlift pump.

Gas state equation and flow mechanism of gas–liquid two-phase flow in airlift pump system

Airlift pumps (ALPs) have a simple structure and significant application potential. However, previous studies on ALPs have generally assumed that the gas density remains constant. In this paper, the gas state equation (GSE) for ALP is established based on the van der Waals formula, which explicitly considers the density of gas. An electrical resistance tomography system is used to collect the gas void fractions at different heights under different gas flow rates, and an empirical formula for the gas void fraction is established. To verify the effectiveness of the proposed model, high-precision pressure sensors and a high-speed camera are used alongside an electrical resistance tomography system to determine the realistic ALP flow parameters. The results of 409 sets of experiments show that: (1) the gas in ALP cannot be regarded as ideal gas, because the ideal GSE cannot distinguish between different gas flow rates; (2) the state change of gas in ALP is a quasi-equilibrium process, whereby the GSE of ALP can be obtained from the pressures under several locations; (3) the axial pressures predicted by the proposed GSE for ALP are in good agreement with experimental data; and (4) a single parameter of the GSE uniquely determines the state process. The proposed model and the experimental data provide a new methodology and comprehensive references for studying the working mechanism and efficiency of ALPs.

Performance characteristics of the airlift pump under vertical solid–water–gas flow conditions for conveying centimetric-sized coal particles

In this study, the installation of an airlift pump with inner diameter of 102 mm and length of 5.64 m was utilized to consider the conveying process of non-spherical coal particles with density of 1340 kg/m3 and graining 25–44.5 mm. The test results revealed that the magnitude of increase in the solid transport rate due to the changes in the three tested parameters between compressed air velocity, submergence ratio, and feeding coal possibility was not the same, which are stand in range of 20%, 75%, and 40%, respectively. Hence, creating the optimal airlift pump performance is highly dependent on submergence ratio. More importantly, we measured the solid volume fraction using the method of one-way valves in order to minimize the disadvantages of conventional devices, such as fast speed camera and conductivity ring sensor. The results confirmed that the volume fraction of the solid phase in the transfer process was always less than 12%. To validate present experimental data, the existing empirical correlations together with the theoretical equations related to the multiphase flow was used. The overall agreement between the theory and experimental solid delivery results was particularly good instead of the first stage of conveying process. This drawback can be corrected by omitting the role of friction and shear stress at low air income velocity. It was also found that the model developed by Kalenik failed to predict the performance of our airlift operation in terms of the mass flow rate of the coal particles.

Understanding effects from overburden drilling of piles—a rational approach to reduce the impacts on the surroundings

This paper presents two case studies dealing with undesirable impacts of overburden drilling of casings for end-bearing piles to bedrock. Monitored pore-water pressures and ground settlements are used to document and assess the influence from rotary percussive drilling with “down-the-hole” (DTH) hammers. The studies show that drilling with high-pressure air-driven DTH hammers may cause considerable erosion and soil volume loss adjacent to the drill bit and along the casing, resulting in settlements of the surrounding ground. The risk of soil volume loss increases when the drilling is carried out in erodible soils such as silt and fine sands. The volume loss is found to be caused by a combined air-lift pump effect and a Venturi suction effect. Monitoring pore pressures in the vicinity of the drilling may be used to reduce soil volume loss and prevent damaging settlements. Results from drilling with water-driven DTH hammer showed significantly less ground settlements and influence on pore pressures compared to using an air-driven hammer. The study suggests that the drilling parameters flow rate and penetration rate, and the cross-sectional area of the pile casing can be combined in a non-dimensional methodology to assess the mass balance of drill cuttings when drilling with water flushing. A design framework is suggested to guide overburden drilling in urban settings to reduce potential impact on the surroundings.

Numerical analysis of air–water two-phase upflow in artificial upwelling of deep ocean water by airlift pump

Artificial upwelling by the use of airlift pump is regarded as an effective way in utilizing deep ocean water and actualizing ocean fertilization. This paper focuses on numerical analysis of steady air–water two-phase flow in a vertical pipe of an airlift system based on one-dimensional multi-fluid model. The depth distributions of 6 physical quantities such as volumetric fractions and axial velocities of two phases, air density and pressure are calculated by solving the governing equations or by integrating the vector form of nonhomogeneous ordinary differential equation for two-phase flow interval. Upon successful verification of the present numerical model through a comparison with precedent theoretical and experimental results in case of a vertical pipe with length of 7.86 m, the model is extended to the case of artificial upwelling from water depth of 2000 m. The effects of submerged depth of air–water mixer on the pumped amount of water and the depth distributions of 6 physical quantities are considered.

Flow pattern dependent model for airlift pumps performance: Analytical simulation and experimental verification

Airlift pumps are widely applied in different industries largely for flow recirculation purposes such as in petroleum exploration, deep-sea mining, wastewater and sewage treatment, and chemical processing industries. Their performance is significantly dependent on the two-phase flow patterns within their riser pipe and difficult to be accurately predicted. Most previous studies have developed mathematical models to predict lifted liquid flow rate and pumping efficiency of these pumps assuming one flow pattern in the pump riser. However, several flow patterns such as bubbly, slug, churn, and annular flow patterns can exist in the pump riser. Furthermore, most of the current models are developed and validated for use with small-diameter riser pipes, mainly tested in laboratory settings, while industrial applications usually utilize larger pump sizes. To address these limitations, the present study aims at developing a mechanistic model that is applicable for use across a wide range of airlift pump sizes. To verify the proposed model, a series of experiments was conducted under a wide range of operating and geometrical conditions. An airlift pump with a riser diameter of 3.175 cm (small pump) was tested in the lab for an adjustable submergence ratio (0.5, 0.7, and 0.9) at inlet air flow rates up to 20 kg/hr. High-speed imaging was carried out to visualize flow pattern within the riser pipe and instantaneous void fraction data was collected using a capacitance sensor to identify flow patterns and transitions. Four large airlift pumps, featuring riser pipe diameters of 5.08, 10.16, 15.24, and 20.32 cm—dimensions commonly encountered in industrial settings—were tested on-site at an industrial facility, with inlet air flow rates of up to 100 kg/hr. The model showed ∓20% agreement with experimental results of both small and large size pumps. The proposed model was also used to analytically simulate the impact of riser pipe diameter and length as well as submergence ratio on an airlift pump’s performance.

Monitoring temporal chlorophyll-a using Sentinel-2 imagery in urban retention ponds receiving a biological-chemical treatment

Eutrophic conditions occur when waterbodies accumulate excessive nutrients, which leads to algae growth, depleted dissolved oxygen, and increased turbidity. To improve water quality, a biological-chemical treatment was implemented using floating treatment wetlands (FTWs) and slow-release lanthanum delivered through airlift pumps. FTWs remove nutrients via plant uptake and denitrification while lanthanum binds and precipitates phosphate from the water column. The study sites, Densmore and Wilderness Ridge Ponds, had two FTWs and two lanthanum airlift pumps installed in 2020 and 2021. Our hypothesis was that if the biological-chemical treatment reduced nitrate and phosphate, algae growth would be limited, water clarity would improve, and benthic vegetation would increase. Chlorophyll-a, the photosynthetic pigment found in plants and algae, was analyzed to create a direct correlation to algae content within waterbodies. Chlorophyll-a samples were collected twice a month at strategically selected, georeferenced locations in both ponds between May and October in 2022. Water samples were collected when the European Union's Sentinel-2 multispectral satellite passed over the study sites. To estimate chlorophyll-a concentrations prior to the biological-chemical treatment, a correlation was developed between the collected chlorophyll-a concentrations and Sentinel-2 band algorithms. Sentinel-2 imagery provided a means to analyze how chlorophyll-a fluctuated before and during treatment. We found the novel band algorithm, 3BR1, had the best correlation (R2 = 0.72). Applying this band ratio for Sentinel-2 images from 2019 to 2022, a Tukey's HSD test analyzed monthly differences between years. The FTW and lanthanum treatment reduced chlorophyll-a concentrations in Densmore Pond, but not in Wilderness Ridge Pond. One likely reason was Wilderness Ridge Pond had a complex irrigation system and was continuously replenished with nitrate-rich groundwater. Our results show Sentinel-2 can be used to predict historical chlorophyll-a concentrations by using the novel 3BR1 band algorithm and that FTWs and lanthanum can effectively reduce algal growth.

Effect of the up-riser pipe diameter discontinuity on the airlift pump performance

The present study was directed towards studying the performance of the airlift pump with variable cross-section up-riser. The effect of one-step and two-step up-riser enlargement and contraction on the performance of the pump was experimentally investigated. The two-phase flow patterns at the region of cross-section change were also visualized and discussed. The results show that for the one-step enlargement up-riser pipe, the minimum air mass flow rate required to start water flow increases as the up-riser total inside volume increases. At high air flow rates, by contrast, as the up-riser pipe average cross-sectional area increases, the pump water capacity increases. Meanwhile, the two performance curves of one-step and two-step enlargement have similar trends, but the two-step enlargement delivers higher water productivity. The preference of using multiple steps in low-to-medium air flow rate range is remarkable, as eddy losses are lower in the gradually reducing pipe. No flow pattern change appears in the expansion section of the two-step expansion riser, while the one-step expansion riser marks a flow transition from slug to churn flow patterns and from annular to churn flow patterns. A comparison between the water productivity of the one-step contraction and the two-step contraction up-risers displays that the two-step contraction exhibits a higher performance. Moreover, comparisons between enlargement and contraction configurations outline that the enlarged pipe configuration lifts larger amounts of water than the contracted configuration.

Evaluation of airlift pump performance for vertical conveying of coal particles

AbstractOne of the crucial aspects of reducing air consumption when conveying particles with an airlift pump is to know the factors that affect the process of particle motion at an initial velocity of zero. To determine the influence of submergence ratio and physical properties of particles (such as size, shape, and mass) on the onset of vertical particle motion, the airlift pump was taken as the research object, and spherical glass together with irregular shaped coal were used as experimental test particles. The results show that unlike the water-solid environment, the start of particle motion in the water-air mixture does not always occur at a certain value of superficial water velocity and this value also increases with increasing submergence level. Among the parameters considered, the role of submergence ratio is much more effective than the dimensions and the shape of the particle, because by increasing submergence from 0.3 to 0.8, it is possible to reduce air consumption by up to 8 times. Based on this study the corresponding theoretical model derived by Fujimoto et al. is optimized, wherein the overall agreement between the modified theory and present experimental data is particularly good. Contrary to Fujimoto, the minimum superficial water velocity for lifting solids in the air-water mixture is not always smaller than water ambient which indicates on optimum submergence ratio higher than 0.7. Finally, a new criterion was introduced to describe the moment of onset of the particle motion as a function of the superficial fluid velocity ratio for each submergence value.

Characterization of particle removal in an airlift pump with a U-bend

This paper investigates the self-cleansing performance of an airlift pump with a U-bend. For this purpose, an experimental setup is used to assess the effect of air flow on the pump's ability to lift water and remove particles under different submergence ratios and particle concentrations. In addition, a simple yet accurate fluid mechanical model is used to interpret the experiments with individual particles and to predict the critical water velocity required for particle removal from the pipe bend.

Research and Application of Airlift Pump to Operate Aquaponics

This paper presents the results of a study on the use of an airlift pump in aquaponics, a model that has been applied and developed for organic food production. Airlift pumps, which are commonly used in the mining industry for pumping liquids such as water and oil, have recently been adopted for use in aquaponics systems. Airlifts offer several advantages over other types of pumps, including a simple and compact design with no moving parts, making them suitable for hanging systems in shallow water. Airlifts also play a dual role in transporting liquids and saturating dissolved oxygen content in water, which is essential for the organisms in the aquaponics system to thrive. To promote these benefits, it is crucial to choose the correct mode of operation for the aeration pump; otherwise, it may decrease efficiency and increase operating costs. In this study, an airlift pump, which combines an aquaponic pump, aerator, and duct system into one compact unit, was used. The experiment was conducted using a riser pipe of different diameters (D = 24, 30, 36, 48 mm), a height (h + H) of 2000 mm, an air pipe with a diameter of 15 mm, compressed air pressure ranging from 0.5 to 4.0 kg/cm2, gas consumption (V) between 0.1 to 1.0 m3/h, and a pump capacity (Q) of 5-39 L/min. The results show that the greatest lifting height can be achieved with a riser pipe diameter of 30-36 mm. At an airflow rate of 0.8-0.9 m3/h and various compression pressures, the dip coefficient of 0.285 produces a maximum pumping capacity of 25-30 L/min.

Development of an efficient numerical model for two-phase flows in air-lift pumps and its application to deep-sea mining

Air-lift pump system has been selected as a potential application to convey the Rare-Earth mud in deep-sea mining processes due to the superior reliability and schematic simplicity. It is a major focus of current research to study the behavior and mechanism of the two-phase flow. Based on the drift flux model and modified Akawa pressure drop equation, mathematical model controlling the numerical simulation of two-phase flow within air-lift pump system is proposed and constructed. Comparison with experimental data concerning steady and unsteady two-phase flows in vertical pipes shows the high precision of the model. Combing with the robustness test results, it can be found that the present model can accurately predict the maximum flow rate of the two-phase flow at the outlet of the gas lift pump, as well as the average gas and liquid flow rates of the two-phase flow at the outlet in both steady and unsteady states. On this basis, several operation laws of the deep-sea mining airlift pump were studied. The relationship between input and output in the mining process is established and the output of the gas lift pump system is predicted. It is found that changing the position of the injected gas, the time for the two-phase flow in the vertical pipe to reach dynamic equilibrium varies equiprimordially. And changing the maximum amount of gas injected, the time required to reach dynamic equilibrium shows a symmetric relationship with the volume fraction after dynamic equilibrium. A series of laws closely related to the prediction of rare earth mud at the outlet of gas-lift pumps in deep-sea mining are investigated to be proposed for subsequent studies.

Ultrasound measurement of large bubbles rising in angled slug pipe flows

This study details the problem of the ultrasonic detection of large bubbles rising rapidly in an upward gas–liquid two-phase pipe flow and proposes a new method to solve the problem. The proposed method uses two types of information, namely the echo intensity reflected by large bubbles and the Doppler frequency, which have different features in interface detection. The method using the Doppler frequency performs well in the detection of large bubbles regardless of the interface condition, whereas the method using the echo intensity has trouble in detecting an uneven interface. In contrast, the information of the echo intensity guarantees high accuracy of the interface detection even if that of the Doppler frequency has low accuracy for the detection owing to many small bubbles existing in the liquid film. Here, the two methods are combined to overcome their problems, and a validation test confirms that the results of the combined method agree well with the results of image processing. As demonstrations of the proposed method, the slug frequency, velocity, and airflow rate of large bubbles in an air-lift pump are obtained. The results confirm that the proposed method can be adopted for the high velocity of slug flow in various applications.

Slow-Release Lanthanum Effectively Reduces Phosphate in Eutrophic Ponds without Accumulating in Fish

Nutrient runoff is a major water quality issue affecting water resources. Excess nutrients such as nitrate (NO3−) and phosphate (PO43−) entering surface waters promote eutrophication. Recent research showed that floating treatment wetlands combined with slow-release lanthanum composites deployed through airlift pumps can reduce NO3− and PO43− concentrations, minimize algae and weeds, and increase dissolved oxygen concentrations. While water quality improves following this biological and chemical approach, questions remain about the toxicity and potential accumulation of lanthanum in lentic organisms. We addressed this concern by analyzing flesh and liver of fish exposed to the slow-release lanthanum following two years of treatment and compared results to fish harvested from a control, untreated pond. We also conducted an aquarium fish study that used higher lanthanum concentrations than those observed in the field. The field study confirmed that under the concentrations of lanthanum released to treat eutrophic ponds (109 µg L−1), no adverse effects were observed in harvested fish. We also observed no significant differences between lanthanum-exposed and -unexposed fish (α = 0.05) in our controlled tank study. Given the laboratory tank lanthanum concentrations were approximately nine times higher (916 µg L−1) than the observed field concentrations, we conclude the slow-release lanthanum composites used to treat eutrophic ponds are effective in improving water quality and do not lead to significant lanthanum accumulation in fish.

Membrane Bio-Reactor using Airlift Pump to Maximizing of Membrane Recovery

Membrane Bio-Reactor using Airlift Pump to Maximizing of Membrane Recovery

Critical characteristics of an airlift pump for dredging

There are many factors that affect an airlift pump for dredging. In actual applications, if these factors cannot be fully considered, the performance of the airlift pump will be reduced. In view of this, based on the critical model of the water–solid two-phase flow and the gas holding model, a critical model of the gas–water–solid three-phase flow is proposed. The research results show that, compared with the two-phase flow, the critical water flow rate for lifting solids in the three-phase flow is always smaller. Therefore, it is necessary to consider the static chip retention force so that the critical model in the two-phase flow can be modified. It shows that the static chip retention effect is opposite to the “start” of the particle. Not only that, but also discussed are the critical conditions of solid particles or vertical lifting water from a practical point of view. The results show that solid particles will not affect the critical air flow rate of pumping water. However, the size and location of the solid particles affect the critical air flow rate.