Gas-liquid Mixture Research Articles

Damping properties of a two-phase mixture of transformer oil with gas bubbles

In recent years, gas–liquid media are of interest due to their damping properties, which may be sufficient to prevent the mechanical destruction of the oil-filled equipment in consequence of electrical breakdown. For this purpose, an experimental installation was created, where the classical method of electric explosion of a wire is used to study the damping properties of a gas–liquid mixture. Microbubbles with a diameter of 1 mm and 0.5 mm were generated with a tangential air supply in a narrowing part of the Venturi tube or using a Laskin nozzle, respectively. Studies have shown that when the oil is aerated with 1 mm bubbles, final waves amplitude, decreases almost by 5 times, and when gassing with 0.5 mm bubbles the amplitude, decreases by more than 10 times. The attenuation of the amplitude of the pressure wave by a factor of the Euler number e in pure oil occurs in ≈ 7 ms, the bubbles with a diameter of ≈ 1 mm lead to an attenuation in ≈ 5 ms, and the bubbles with diameter of ≈ 0.5 mm in ≈ 2 ms.

Gas-liquid two-phase flow measurement by combining a Coriolis flowmeter with a flow conditioner and analytical models

Abstract In oil-gas fields, two phase flow measurement of liquid-gas mixture for the whole Gas Void Fraction (GVF) range remains a challenging task. Coriolis flow meter is proven to be one of the most accurate device for single phase flow measurement. However, for two phase flow metering, its accuracy gets altered for liquid continuous phase (respectively gas continuous phase) in case of GVF that exceeds 20% (respectively low GVF that is lower than 80%). This paper presents a new Coriolis-based two phase flow meter (TPFM) that uses an upstream inline flow conditioner which separates liquid (i.e. water in this paper) from gas. Each of the gas dominant phase and liquid dominant phase are carried by two outlets, namely gas and liquid outlets respectively. A Coriolis flow meter and an actuated valve are placed in each outlet to measure and regulate the GVF that passes in each line. A new measurement algorithm based on a multistage artificial neural network (ANN) and which explores the physical model of the Coriolis flow meter is also suggested. This latest combines the pressure-volume-temperature (PVT) and bubble theory models to estimate the amount of gas (respectively liquid) dissolved in the liquid phase (respectively gas phase). Experimental results that were conducted on a multiphase flow loop reveals that for the whole GVF range (i.e. 0 to 100% GVF), the absolute value of the relative error on both the mass flow rate and density does not exceed 2.5%. This suggests that the proposed TPFM can be considered as a new non-hazardous alternative for accurate two phase flow measurement.

ОРТАДАН ТЕПКІШ СОРҒЫЛАРДЫ ЖЕТІЛДІРУ ҮШІН ГАЗ СЕПАРАТОРЛАРЫН ҚОЛДАНУ

In this article, the problem of monitoring the energy consumption of electric centrifugal pumps and the method of application in the fields with the use of gas separators on the basis of reducing the harmful gas impact on electric centrifugal pumps is developed. Methods of optimization of power consumption by borehole pumps are considered. Conducting comparative bench tests of new stages of a centrifugal pump designed for pumping gas-liquid mixtures (GLM), and determining the degree of influence of free gas on the operating parameters in the entire possible working area of the stage when pumping model GLM. It is concluded that the technology of electric centrifugal pumps is used.

Developments Made in the Field of Drilling Fluids by Saint Petersburg Mining University

The article discusses researches performed in the Well Drilling Department of the St. Petersburg Mining University. The directions of development of the department are shown. Special attention in this article is paid to research in the field of developing drilling fluids for drilling wells in various mining and geological conditions. It is shown that the gas-liquid mixtures studied by the department will be effective for under balanced drilling under conditions of abnormally low reservoir pressures when using a binary mixture of sodium lauryl sulfate 0.5% + linear sodium alkyl benzene sulfate 0.5% as a surfactant and polyacrylamide FP complex 107 (0.05%) as a forming and stabilizing additive + carboxymethyl starch BUR-2 (1%). Studies in the field of development of inhibitory fluids have shown that an increase in the concentration of polar compounds in the drilling fluid compared to their concentration in the rock Cp> Cn by 0.25 mol/L makes it possible to increase the stability of the rocks around the wellbore compared to the initial conditions. Studies of lubricating additives showed that introducing 1.5–2.0% of FRW additive reduces the friction coefficient of the metal– metal pair in a clay solution by 70–75% and in an aqueous solution up to 65%. The findings suggest that drilling fluids developed at the Well Drilling Department of the St. Petersburg Mining University have a high potential for their application in oil and gas fields in order to improve the efficiency of drilling and completion of wells. It is also noted that the scientific and technical potential of the department allows for input control of reagents in drilling fluids, as well as the development and research of various compositions not only for drilling and completion of wells, but also for development and repair, which are applicable in real field conditions.10.5829/ije.2020.33.04a.22

The Research and Well Performance Simulation under Conditions of West Siberia

The paper proposes a new method of calculating the pressure at the pump intake, taking into account changes in the density of the gas-liquid mixture in the well depth. An algorithm for performing the pressure calculation is presented. Graphs of pressure distribution in the well depth with different gas content in comparison with the traditional method for calculating pressure are given. The importance of taking into account the physical properties of gas depending on the depth was proved.

Simulation of regenerative pump performing on multiphase mixture

The features of gas-liquid mixtures hydrodynamic modeling during the separation process are described. The paper considers the model of a centrifugal pump, which is a part of mobile objects, such as wheeled and tracked vehicles etc. The simulation is carried out in the STAR-CCM + software. A comparison of the effect of gas separators various designs on the flow during the operation of the pump on a two-phase mixtureis carried out and the most suitable configuration is identified.

The Influence of Determining Factors on the Parameters of Gas-lift Operation of Flooded Gas Wells

The development of gas deposits at the final stage is usually complicated by watering production wells. With the advent of water in the formation product, the gas production rate decreases due to the decrease in the gas-saturated thickness of the reservoirs and the increase in pressure loss during movement of the liquid-gas mixture in the wellbore and flow lines as compared to the movement of gas only. Well operation is gradually becoming unstable, periodic with the subsequent cessation of natural flowing. The methods of operation of flooded wells are characterized. The use of the gas-lift method for the operation of flooded gas wells in depleted gas fields is justified. The effect of tubing diameter, wellhead pressure and water factor on the parameters of gas-lift operation of flooded wells is investigated. The research is carried out using the improved technique proposed by the authors and the PipeSim program for hypothetical (simulated) well conditions. The studies performed are presented in the form of graphical dependences of the production rate of reservoir gas, the minimum required gas production rate for the liquid to be taken from the bottom of the well to the surface, lift gas flow rate and bottomhole pressure on wellhead pressure, diameter of tubing and water factor. The research results indicate a significant coincidence of the values ​​of the calculated parameters of the gas-lift operation of the watered well according to the proposed methods and the PipeSim program. Using the research results, it is possible to select the optimal diameter of the tubing string and evaluate the value of formation gas flow rate and gas-lift flow rates for various values ​​of water factor and wellhead pressure.

Analysis of the application of jet pumps in the field development in Western Siberia

Currently, the use of jet devices in the oil and gas industry is constantly expanding. The reason for this expansion in the oil and gas industry is the presence of a number of advantages. One of the advantages is the compactness of the working section. Other advantages of the jet pump are the simplicity of its de-sign, high reliability and unique technical capabilities when pumping gas-liquid mixtures, the absence of moving mechanical parts, low criticality to the content of mechanical impurities and viscosity of the extracted liquid. The aim of the study is to analyze the use of jet devices during well develop-ment in Western Siberia.

Gas–liquid two‐phase flow characteristics of the jet vortex drainage gas production tool based on computational fluid dynamics

AbstractThis study is aimed at the problems of traditional vortex tools in gas wells, including notable pressure losses and short effective distances. An organic combination of jet vortex drainage and gas production tools was designed and installed without additional power equipment. Based on the liquid film force balance model, gas–liquid two‐phase flow and turbulence models of the jet vortex tool were established with UG and Fluent flow simulation software. The gas–liquid mixture was analyzed before and after the jet vortex tool, and the flow trajectory, pressure loss, liquid volume fraction change, and change rate were examined. According to the simulation results, the comprehensive influence of each structural parameter on the effective working distance was optimized, and optimal structural parameters of the jet vortex tool were obtained. The results indicate that the jet vortex tool reduces the critical liquid‐carrying flow rate and pressure loss and increases the axial and initial velocities of the gas and liquid phases, combined with swirl tool distance model, the effective flow distance is increased correspondingly, and the liquid‐carrying capacity of the gas well is improved.

Hydrodynamics of the vortex tray

The article presents geometry, dimensions and structural characteristics of tangential swirlers of different design for vortex plates, which are a new type of centrifugal tray. The results of hydraulic tests of the vortex plate with tangential swirlers for an air–water system are given. The research allowed determining the flow regimes of the gas–liquid mixture at the tray and presenting the dependence for determining the critical gas velocity in the channels of the device characterizing the transition from the bubbling flow regime to the annular one. The dependences for calculating the coefficient of hydraulic resistance of the dry tray and the total resistance are determined. The gas content in the rotating liquid layer was studied with determination of the design parameters of the device that affect its value. The values of the angular velocity of the gas–liquid layer are established. The height of the rotating gas–liquid layer is determined and the equation for its calculation is presented. The medium-surface diameter of the gas bubbles in the liquid in the annular flow was 2–3 mm and the interfacial area of the gas–liquid layer was calculated as 600–1,200 m−1.

The sloshing effects on distribution characteristics of gas–liquid mixture in spiral-wound heat exchanger

Spiral-wound heat exchanger (SWHE) is important equipment for industry, and it is suitable for floating production storage off-loading (FPSO). However, two-phase mixture maldistribution always restricts the heat transfer capacity of SWHE in FPSO. Few studies have focused on the maldistribution of SWHE. According to this, an experimental device was fabricated to evaluate the maldistribution of a novel distributor on the sloshing platform. The effects of vapor qualities and mass flow rates were analyzed at the range of 0.106–0.702 and 608.5–1491.6 kg h−1, respectively. The following conclusions are drawn: With the augmentation of vapor quality, the gas–liquid uniformity deteriorates after optimizing under steady and sloshing conditions. Heave condition improves gas and liquid flow uniformity by 2.9–11.0% and 1.7–3.7% separately, and pitch condition improves the gas flow uniformity by 0.5–3.7%, and roll condition lowers the liquid flow uniformity by 2.0–7.2% in the variation of vapor quality. It is also proved that the flow uniformity achieves better performance with the increasing mass flow rate under steady, heave and pitch conditions. Heave condition improves the distribution characteristic by 4.4–8.7% for the gas phase and 2.0–9.5% for the liquid phase, and pitch condition elevates the gas flow uniformity by 3.1–7.7%. Under the roll condition, the distribution performance of the experimental model changes worse after better and obtains the best performance at the mass flow rate of 1183.8 kg/h. At large mass flow rates, gas entering into liquid space under roll condition can bring the structural problem. Increasing the tube diameter and making the upper baffle tilt from shell to center barrel are beneficial to keep the distributor structure safe.

Numerical investigation and performance enhancement of roots pumps operating with gas-liquid mixtures

The suitability of Roots pumps operating with gas-liquid mixture is investigated. The computational fluid dynamics method is employed and validated against experimental results. To highlight flow characteristics of Roots pumps operating with gas-liquid mixtures, the Roots pumps operating with pure gas and liquid are included as the reference case. A pump efficiency of 48% is attained for the gas-liquid mixture at the volume ratio of 4:1, while the efficiency of 59% for gas and 80% for liquid are achieved, respectively. The reduced pre-compression effects and the resulting high-pressure difference between the outlet and the working chamber are found to be reason for low efficiency. To enhance performance, increasing the gap between the rotor and casing is utilized. It is demonstrated that the flow efficiency is increased, while the volumetric efficiency cannot be maintained due to the increased leakage through the gap between two rotors. Alternatively, the configuration with the gradually varied gap near the pump outlet is employed. The pump efficiency is significantly enhanced due to increased pre-compression effects, while the high volumetric efficiency can also be maintained. The work provides the insight into flow characteristics of Roots pump operating with gas-liquid mixture.

Conceptual features for improving the flow part of the multiphase stages of ESP submersible plants for small and medium feeds for extracting stratal liquid with a high free gas content

AnnotationThis article analyzes the operation numerical simulation for serial and multiphase stages of various manufacturers on water and gas-liquid mixtures (GLM). Are identified the local gas separation areas in serial stages, which can lead to the formation of gas plugs and disruption of the pump supply.These factors include: the creation of a finely dispersed flow structure at the entrance of the stage, the preservation along the flow with small free gas bubbles diameters, the sustenance of the value for the allowed free gas content by circulation means of fluid part in the impeller, a defined relationship between the pressure gradient and the GLM flow rate. A mathematical model is selected, hydrodynamic calculations of structural options, optimization are carried out, a conceptual option is selected. Bench tests were carried out, confirming the high parameters of the product when working on GLM.

Conceptual features of improving the flow-through parts of gas separators of submersible electric pumps systems f for the production of formation fluid in order to improve the separating properties, energy efficiency and reliability

This article analyzes the design of the power part of gas separators of various manufacturers, reveals the causes of backflows, which can lead to hydro-abrasive wear of the elements of the flow-through part, reduction of the separation properties as a result of the gas-liquid mixture flow dispersion, and decrease of pressure gradient in the separation chamber. A mathematical model was selected, hydrodynamic calculations of design options and upgrading were carried out, and animproved flow part of the separator was developed. Bench tests were conducted to confirm the improved parameter of the product.

A cost-effective production of hydrogen peroxide via improved mass transfer of oxygen for electro-Fenton process using the vertical flow reactor

This study has investigated a novel jet-type reactor (vertical flow reactor) in order to improve the oxygen utilization for enhanced production of hydrogen peroxide (H2O2). In vertical flow electro-Fenton (EF) system, the effects of current density, water flow rate, Fe2+ concentration and initial pH were investigated for the removal of tetracycline hydrochloride. The efficient removal of tetracycline hydrochloride could reach 100% within 60 min under the current density of 24 mA cm−2, water flow rate of 10 L h−1 and pH of 3. The vertical flow reactor was relatively stable and reusable for the removal of pollutants. The removal rates of tetracycline hydrochloride and total organic carbon (TOC) were maintained at about 95% and 80%, respectively in a 5-time continuous runs. Moreover, the vertical flow reactor could efficiently remove a wide type of organic pollutants, and the TOC removals of acid magenta, rhodamine B, alizarin yellow R, orange Ⅳ and diclofenacdium were 75.96, 77.90, 61.27, 72.11 and 82.89%, respectively after 3 h of reaction time. Cathodic adsorption, anodization, and H2O2 oxidation played minor roles in the removal of tetracycline hydrochloride, while the OH radicals are the most pivotal oxidizing substance in the system. As compared with the traditional aeration, the vertical flow reactor has a high-speed jet flow state, which makes the liquid-gas mixture homogeneous, and renders it high oxygen absorption rate, cost effectiveness and high power efficiency for the degradation of pollutants.

Synergetic effect of photocatalysis and ozonation for enhanced tetracycline degradation using highly macroporous photocatalytic supports

Photocatalysis and ozonation have limited efficiency for the degradation of persistent pollutants as well as the mineralization of byproducts. In this work, we intensify the degradation processes by using simultaneously both processes in macroporous catalytic supports under mild reaction conditions, for degradation of tetracycline. The total organic carbon removal reached up to 90% after 180 min of photocatalytic ozonation reaction, achieving this record value using mild conditions. A comparison among processes showed the synergetic effect of photocatalysis and ozonation carried out in the macroporous support, which presents a kinetics increase of ≈20% greater than the sum of the separated processes. About 100% of tetracycline degradation was achieved with a high total organic carbon removal. This effect is attributed to synergy with the porous structure, which promote better O3 and O2 species mass transfer, due to the tortuosity and turbulence developed within the structure channels, coupled with a augmented residence time of the reactants. The gas-liquid mixture moves slower inside the porous channels, the apparent relative viscosity of a bubble train can be orders of magnitude larger than the viscosity of the pure liquid within the channels. In this work conditions were estimated as 10 times greater per bubble. The better species distribution, the increased residence time, and e−/h + recombination hindering along an increase of free hydroxyl radicals improved the overall degradation of tetracycline, avoiding the use of free catalysts and allowing the direct reuse of the system.

Ultrafast X-Ray Computed Tomography Imaging for Hydrodynamic Investigations of Gas–Liquid Two-Phase Flow in Centrifugal Pumps

AbstractGas entrainment into centrifugal pumps decreases pump performance and may raise safety issues, e.g., through insufficient cooling. Although there is some phenomenological knowledge in the form of correlations between operating parameters and pump performance, a further understanding via direct observation of the gas–liquid mixture was so far not possible. In this paper, we demonstrate the capability of ultrafast X-ray computed tomography (UFXCT) to disclose gas–liquid two-phase flow dynamics in the impeller region of a centrifugal pump mockup. Experiments were performed for gas injection at impeller speeds between 1300 rpm and 1600 rpm. We analyzed the X-ray image sequences with respect to characteristics of the gas distribution and compared them with time-averaged image data of a real pump obtained earlier with gamma-ray computed tomography (CT).

Effects of bubbles in the liquid jet on the air-blast atomization

The air-blast atomization with bubbles in the liquid jet was investigated using the high-speed camera and Malvern laser particle size analyzer. The gas was aerated into the liquid jet to form the gas-liquid mixture, which would be atomized by the co-flowing air stream. Results show that droplet size D32 decreases at the beginning and then increases with the volumetric flow rate of the aerating gas. A formula was derived to delineate the nonmonotonic trend of the droplet size. The relative deviations between the predicted results and experimental results are less than ±5%. A contour map describing the dependence of the droplet size on the aerating gas, liquid jet, and co-flowing air stream was obtained, which could provide some guidance for the further investigations and industrial applications.

Physical and numerical study on unsteady shedding behaviors of ventilated partial cavitating flow around an axisymmetric body

The objective is to investigate the unsteady ventilated partial cavitating flow characteristics with focus on the unsteady shedding behaviors via combined experimental and numerical methods. Experimental results are presented for an axisymmetric body in a water tunnel with the flow pattern recorded by a high speed camera. The numerical simulation is performed with a filter-based turbulence model. Good agreement can be obtained between the experimental and numerical results. The ventilated cavity around the axisymmetric body experiences the rapid growth stage, the growth with small pulsation stage and the periodic shedding stage. The typical ventilated cavitating flow patterns at different angles of attack have also been studied to further investigate the effect of the asymmetry on the unsteady shedding behaviors of ventilated partial cavitating flow. With the increase of the angle of attack, the ventilated cavity develops asymmetrically and the non-transparent gas-liquid mixture region is gradually concentrated on the opposing stream surface along with the transparent cavity region increasing on the confronted stream surface.

Effect of Thickness Ratio Coefficient on the Mixture Transportation Characteristics of Helical–Axial Multiphase Pumps

With the decrease of oil and gas resources on land, increased attention has been paid to multiphase oil–gas exploitation and the transportation technology represented by oil–gas multiphase pumps. The helical–axial multiphase pump has become the focus of research on oil and gas mixed transmission technology due to its relatively high operating efficiency and adaptability to a wide range of gas volume fraction changes. In order to investigate the thickness variation in the air foil from the hub to the shroud of the blade on the mixture transportation characteristics of the gas–liquid two-phase flow in a helical–axial pump, the thickness ratio coefficient ξ was introduced, and the hydraulic performance of the single compression unit with different thickness ratio coefficients was investigated. A single compression unit including an impeller, diffuser, inlet section and outlet section of a helical–axial multiphase pump. The hydraulic performance including the hydraulic head and efficiency was investigated by numerical simulation with the Eulerian multiphase model and the shear stress transport (SST) k-w turbulence model. In order to demonstrate the validity of the numerical simulation approach, the hydraulic head and efficiency of the basic model was measured based on a gas–liquid two-phase flow pump performance test bench. The simulation results agreed well with the experimental results; the error between the simulation results and experimental results of different inlet gas volume fractions was within 10% at the design point, which indicated the numerical simulation method can be used in the research. The thickness ratio coefficient ξ, which was taken as a variable, and the aggregation degree λ of the gas were introduced to analyze the gas–liquid mixture transportation characteristics of the pump. The thickness ratio coefficient was selected in a range from 0.8 to 1.8. The results showed that, for the same hub thickness, the head coefficient and efficiency increase, and the aggregation degree of gas decreases with the decreasing of the thickness ratio coefficient. The head coefficient of the modification multiphase pump was 5.8% higher in comparison to the base pump while the efficiency was 3.1% higher than that of the base pump, the aggregation degree of this model was the lowest, which was 30.3%; the optimal model in the research was the model of scheme 1 with ξ = 0.8. The accumulation of gas in the flow passage of the impeller could be delayed to the trailing edge of the blade by adjusting the thickness ratio coefficient, which produced a super-separated airfoil for helical–axial multiphase pumps and effectively ensured reliable operation under high gas volume fraction conditions. The accumulation area of gas was consistent with the area in which the gradient of turbulent kinetic energy was large.