Flow Of Gas-liquid Mixture Research Articles

METHOD OF GAS PRESSURE OPTIMIZATION IN PRODUCING WELL ANNULUS

The process of oil production using sucker rod-pumping installations, especially with high gas content of formation fluid, is accompanied by accumulation of oil gas in the annulus of wells. The growth of the annular gas pressure causes an increase in the back pressure on the reservoir and a number of other negative consequences, to exclude which various technologies are used to pump out gas from the annular space of production wells. The article considers the problem of optimizing the gas pressure in the annulus by pumping gas with a compressor at a constant speed. The design of the suspended plunger compressor driven by the balance of the pumping unit and the method for calculating the technological parameters of the compressor based on the balance of the compressor supply and the volumetric flow rate of the separated gas into the annulus are proposed. A two-stage algorithm for calculating the parameters of the optimal technological mode of well operation has been developed. As an optimization criterion, joint fulfillment of the following conditions was proposed: ensuring the permissible volume fraction of gas at the inlet, minimum pump immersion under the dynamic level, and maximizing the flow rate of the well. To assess the effectiveness of the proposed well operation technology and to calculate the increase in well flow rate during compressor operation, a mathematical model of a multiphase stationary gas-liquid mixture flow in a wellbore operated by a pumping pump unit, taking into account the equilibrium processes of separation and dissolution of oil gas, the effects of oil and gas phase slip, is proposed. The calculation results confirm that the use of compressors for pumping gas from the annulus allows one to obtain a significant increase in the flow rate of liquid and oil, which depends on the parameters and properties of the pumped product, the operational characteristics of the formation and barothermal conditions.

Digital Light Processing 3-Dimensional Printer to Manufacture Electrolyzer Bipolar Plate

Bipolar plate is one of the largest and most important components in Polymer Electrolyte Membrane Electrolyzer and Fuel Cell that functions as a cell separator, electrical and heat conductor, reactant feed distributor, for the flow of gas-liquid mixture and supporting components for the Membrane Electrode Assembly. In general, injection, compression moulding or Computer Numerical Control-machines are commonly used to produce bipolar plate. These methods, however, cannot be used to produce complex 3-dimensional shapes, such as vertically inverted cone shape or creating a channel inside the plate. By using a 3-dimensional printing machine with laser-based stereolithography or digital light processing, complex design problems and problems in making channels in the plate can be solved easily. In this study, polymer-based bipolar plate was developed using 3-dimensional printing technology which was made conductive by introducing nickel and gold layers through spray coating and electrocoating processes. The nickel layer was optimized by controlling the applied voltage during electrocoating. Since low voltage formed very thin layer whereas high voltage caused “burning” of the sample, applied voltage of 5V was found to be the optimum condition. Employment of gold layer increases the conductivity from 300 S cm−1 to 400 S cm−1 which enabled the corrosion current density to drop to 0.470 uA cm−2, meeting the standard set by US Department of Energy. The porosity test also proved that the bipolar plate was impermeable to hydrogen gas. Therefore, this manufacturing method has great potential to be used for the production of sophisticated electrolyzer cell or fuel cell in the future.

Verification of methods for calculating the gas volume fraction in the vertical descending flow of two-phase gas-liquid mixtures

The paper presents the results of research on the vertical falling flow and their analysis. Methods for calculating the gas volume fraction, which are characterized by high accuracy, and are often proposed in the literature. Their accuracy was presented, as well as the methods with the highest computational usefulness when designing devices in which two-phase gas - liquid flow is used.

Investigation on inner flow field characteristics of groove textures in fully lubricated thrust bearings

PurposeThe purpose of this study is to investigate the inner flow field characteristics of groove textures in thrust bearings. Cavitation and vortex are studied simultaneously to enrich the theories of surface texture.Design/methodology/approachNavier–Stokes equations are solved using computational fluid dynamics. The MIXTURE model is adopted to study the gas–liquid mixture flow under the cavitation condition.FindingsRe number, the depth ratio as well as the area ratio of the groove texture and the bottom shape are all influencing factors of the inner flow field characteristics. When cavitation region and vortex region occupy the bottom of the groove texture, these do not overlap because of the pressure gradient. The positive pressure gradient in the non-cavitation region introduces nonlinearity into the velocity profiles, which affects the load-carrying capacity and friction.Originality/valueCavitation and vortex are studied simultaneously only in this study. The characteristics of the textured thrust bearing can be analyzed and explained with the combined effect of cavitation and vortex.

ИССЛЕДОВАНИЕ ПРОЦЕССА ТЕПЛООТДАЧИ ПРИ ГИДРИРОВАНИИ РАСТИТЕЛЬНЫХ МАСЕЛ В СТАЦИОНАРНОМ СЛОЕ КАТАЛИЗАТОРА

In this research, we investigated the process of heat transfer from the mixture of cottonseed oil and hydrogen to the reactor wall during a vegetable oil hydrogenation reaction in a fixed-bed catalytic reactor. The dependence of the heat transfer coefficient on the flow rate of the gas-liquid mixture, and consequently, on the mixture feeding regime in the reactor, was established. The elucidation of the heat transfer mechanism during hydrogenation is important for controlling the process concerned. This process is known to occur with a significant thermal effect, which can lead to the overheating of the reactor and undesirable reaction products. The temperature regime determines not only the selectivity and rate of the chemical reaction, but also on the overall performance of the hydrogenation reactor. In this research, the process was studied using cottonseed oil with the addition of 30% hydrogenate and technical hydrogen. Nickel alloy in pellets with a size of 3-5 mm was used as a hydrogenation catalyst. The process was simulated in a reactor, which consisted of a thin-walled heat-insulated copper tube under a continuous heating regime. The temperature of the inner reactor wall was maintained constant at the level of 200 °C. The temperature inside the reactor was monitored using a four-zone thermocouple reader. As a result, dependencies between the heat transfer coefficient and the gas-liquid mixture flow regimes in the reactor have been established. The obtained dependencies provide a better understanding of heat transfer processes occurring in fixed catalyst beds. In order to increase the efficiency of vegetable oil hydrogenation, these dependencies should be taken into account during both the design of hydrogenation reactors and their operation. The calculation of the surface area, where the heat transfer takes place, and the amount of coolant used in the reactor is possible only with the use of these dependencies.

Multiscale modeling of nonequilibrium gas–liquid mixture flows in phase transition regions

ABSTRACTThis paper presents multiscale modeling substantiated with experimental aspects of state, filtration, and motion of the gas–liquid mixtures involving phase transition regions in concentrated volumes applicable to porous media and pipe flows. Based on physics, it is confirmed analytically that actual levels of underpressure in gas–liquids systems are considerably above traditional understanding of saturation pressure at which gas emission from the liquid and its dissolution in the liquid in a form of embryos can occur. It is demonstrated that these processes are not equilibrium processes, and they can also occur on nanoscales and microscales. Thermo-hydrodynamic analyses and experimental investigation of the gas–liquid systems in areas of phase transition presented here have resulted in useful equations governing such flows in filtration in the porous media and in straight pipes.

Fuzzy inference for two-phase gas-liquid flow type evaluation based on raw 3D ECT measurement data

Industrial diagnostic and monitoring systems still require new methods offering new possibilities of non-invasive observation and analysis of the two-phase gas–liquid mixture flows. This paper demonstrates an application of fuzzy methods for the purpose of the two-phase gas-liquid flow type evaluation. It has been demonstrated that the fuzzy inference using raw 3D Electrical Capacitance Tomography (ECT) measurement data and some contextual information such as gas and liquid flow stream in the two-phase mixture flow may be sufficient alternative to the methods commonly used in this field. A series of experiments has been completed using the test flow rig and the results of the recognition (human expert contra fuzzy inference) were compared. Fuzzy logic supported with the non-invasive 3D ECT measurement have proved to be suitable for the identification task applied for the dynamic two-phase flow processes ensuring the accuracy as good as the human expert work. However, the proper preparation of the inference system mechanism guarantees the high quality of the recognition results.

A study on the gas–liquid mixture flow characteristics inside in-line type subsea separator

A study on the gas–liquid mixture flow characteristics inside in-line type subsea separator

Mathematical Simulation of Unsteady-State Gas–Liquid Mixture Flow in a Bed–Well System

Based on theoretical investigations, the influence of various forms of pressure variation at the wellhead with a nonstationary flow of a two-phase fluid in a bed–well system on the character of change in the bottom-hole pressure has been investigated, which makes it possible to determine this pressure from the wellhead operation parameters. The trapezoidal form of the change in pressure is considered as an example. The coupled equations of filtration and the equations describing nonstationary motion of a gas–liquid mixture in a pipeline have been solved jointly. Analytical formulas have been obtained allowing one to determine the bottom-hole pressure from the technological parameters at the wellhead with account for the dynamic connection of the bed–well system at different forms of change in the wellhead pressure. The influence of the wellhead pressure pulsation frequencies on the bottom-hole pressure dynamics has been established.

Attenuating severe slug flow at large valve opening for increased oil production without feedback control signal

In the co-current flow of gas-liquid mixtures through pipeline-riser system, severe slugging is frequently encountered and manifests in significant fluctuation of flow and pressure. This can pose serious threat to production facilities. The most common method for its mitigation is by choking which unfortunately could negatively affect production. The objective of this study therefore is to develop a technique that can help stabilise the system and maximise production simultaneously.In this paper, a new general method for multiphase flow system stability analysis was proposed based on a new passive attenuation method – the intermittent absorber. A series of experiments were carried out in a 4″ pipeline-riser system which is 55m long with horizontal pipe inclined at −2° connected to 10.5m high catenary riser followed by 3m horizontal topside section. Air and water were used as experimental fluids. Numerical studies were also conducted on a 4″ pipeline-riser system to proof the concept.The results showed that the intermittent absorber possess potential for stabilising severe slug flow at larger valve opening and lower pressure. For the case studied, up to 9% reduction in the riser base pressure was reported which practically implies increased oil production.

Bubbling behaviors induced by gas-liquid mixture permeating through a porous medium

This paper investigates the bubbling behaviors induced by gas-liquid mixture permeating through porous medium (PM), which was observed in developing immersion lithography system and was found having great differences with traditional bubbling behaviors injected with only gas phase through the PM. An experimental setup was built up to investigate the bubbling characteristics affected by the mixed liquid phase. Both the flow regimes of gas-liquid mixture in micro-channel (upstream of the PM) and the bubbling flow regimes in water tank (downstream of the PM) were recorded synchronously by high-speed camera. The transitions between the flow regimes are governed by gas and liquid Weber numbers. Based on the image analysis, the characteristic parameters of bubbling region, including the diameter of bubbling area on PM surface, gas-phase volume flux, and dispersion angle of bubbles in suspending liquid, were studied under different proportions of gas and liquid flow rate. Corresponding empirical correlations were developed to describe and predict these parameters. Then, the pertinent bubble characteristics in different bubbling flow regimes were systematically investigated. Specifically, the bubble size distribution and the Sauter mean diameter affected by increasing liquid flow rate were studied, and the corresponding analysis was given based on the hydrodynamics of bubble-bubble and bubble-liquid interactions. According to dimensionless analysis, the general prediction equation of Sauter mean diameter under different operating conditions was proposed and confirmed by experimental data. The study of this paper is helpful to improve the collection performance of immersion lithography and aims to reveal the differences between the bubbling behaviors on PM caused by only gas flow and gas-liquid mixture flow, respectively, for the researches of fluid flow.

Mathematical simulation of gas–liquid mixture flow in a reservoir and a wellbore with allowance for the dynamical interactions in the reservoir–well system

Fluid dynamic processes related to mature oil field development are simulated by applying a numerical algorithm based on the gas–liquid mixture flow equations in a reservoir and a wellbore with allowance for the dynamical interaction in the reservoir–well system. Numerical experiments are performed in which well production characteristics are determined from wellhead parameters.

NUMERICAL MODELLING OF HOMOGENEOUS TWO-PHASE GAS-LIQUID FLOW IN A PIPE

A one-dimensional model which represent a system of partial differential equations that describe mathematically the two-phase flow has been considered for the gas-liquid mixture flow in a pipeline. The Implicit Steger -Warming flux vector splitting method is used for the numerical computation on air-water compressible flow problems. The results for pressure wave propagation, celerity or speed of sound and mass flow rate for different values of mass ratio were obtained. It was observed that the propagation of pressure along the pipeline and the mass flow rate there decreases along the pipe and maintained near a steady flow until it reaches the downstream of the pipe signifying the effect of gas build up during the pump control in pipeline.

The effect of air injection on the parameters of swirling flow in a Turbine-99 draft tube model

Results of experimental modeling of a swirling flow in a Turbine-99 draft tube prototype are presented. The influence of gas phase injection into the flow has been studied. Experiments were performed on a closed hydrodynamic setup containing a working stage with the Turbine-99 draft tube geometry. It is established that the gas content affects the flow structure. Gas injection leads to a change in the frequency of precession of the vortex core formed in the draft tube cone, which is not related to an increase in the gas-liquid mixture flow rate.

Experimental study of air–oil–water flow in a balancing valve

Abstract This paper reports the results of research into air–oil–water flow through balancing valves. The testing applied commercial Zetkama valves. The tests were performed with the use of 4 balancing valves with the nominal diameters of 15, 25, 32 and 40 mm. The testing enabled the determination of the flow patterns forming in the vicinity of the valve. It was concluded that the examined valves do not significant result in flow pattern disturbances. In addition, a correlation was derived which can be used for determining the value of the local pressure drop for the examined type of valves. The presented correlation could be potentially applied for determining pressure drop during gas–liquid mixture flow in industrial installations and apparatus.

Velocity measurements of the liquid - gas flow using gamma absorption and modified conditional averaging

The paper presents idea and an exemplary application of gamma-absorption in the measurement of gas bubbles transportation in a gas-liquid mixture flow through a horizontal pipeline. In the tests on laboratory installation two 241 Am radioactive sources and probes with NaI(Tl) scintillation crystals have been used. For analysis of electrical signals obtained from detectors the modified conditional averaging of the absolute value of delayed signal (CAAV) is proposed. The proposed method is based on the quotient of classical cross- correlation (CCF) and CAAV. Results of the time delay estimation and gas-phase velocity measurements are compared with one obtained using CCF. The combined uncertainties of the mean velocity of air bubbles evaluation in the presented experiment did not exceed 2.1% (CCF) and 1.7% (CCF/CAAV), which is a satisfactory result in industrial applications.

Metrological evaluation of a 3D electrical capacitance tomography measurement system for two-phase flow fraction determination

The industrial diagnostic and monitoring systems still require new methods offering new possibilities of non-invasive observation and analysis of the two-phase gas–liquid mixture flows. This paper demonstrates a new measurement system dedicated for non-invasive void fraction calculation and flow structure identification in vertical and horizontal pipelines. The study of the metrological validation of the designed three-dimensional capacitance tomography measurement system is discussed here. This research includes the 3D ECT sensor structure optimization process, the metrological evaluation of the image reconstruction accuracy and the developed liquid void fraction calculation method efficiency, in comparison with other common techniques. As a result of the performed analysis the advantages of the designed 3D ECT measurement system for non-invasive real-time dynamic flow process identification were discussed.

Integrated hydrodynamic models of oil field development processes

We consider the problems of designing integrated mathematical models for stratum fluids filtration and gas-liquid mixture flows (i.e., oil, natural gas, and water) in oil- and gas-gathering pipelines. The modeling process lies in finding a generalized solution to an initial boundary problem for a system of equations describing real physical processes in oil and gas strata, shafts, and ground-based gathering pipelines. We suggest and study methods to solve the systems of nonlinear algebraic equations defined by the space-time approximation of the initial boundary problems belonging to the class considered.

Local composition shift of mixed working fluid in gas–liquid flow with phase transition

Abstract Local composition shift is an important characteristic of gas-liquid mixture flow with phase transition. It affects the heat transfer process, stream sonic velocity and the mixture distribution in the thermodynamic cycle. Presently, it is mainly calculated through the empirical models of the void fraction from pure fluid experiments. In this paper, we made efforts to obtain it and its rules basing on conservation equations derivation. The result calculated with propane/i-butane binary mixture was verified by the experiment in the evaporator of a refrigerator. As an extending, it was applied to a ternary mixture with components of methane, propane and butane and more information was presented and analyzed. The calculation approach presented in this paper can be applied any multicomponent mixture, and the rules will be helpful to improve the composition shift theory.

Heat and Flow Characteristics of Two Phase Gas-liquid Mixture Flow Over Tube Bundle Using Electrochemical and DPIV Methods

Abstract In the paper authors present results of an experimental investigations of two phase flow across staggered and in-line tube bundles. Flow visualization and velocity distribution were obtained with the use of DPIV technique. Electrochemical, limiting current method was used to measure values of convective mass transfer and Chilton-Colburn heat-mass transfer analogy was applied to obtain Nusselt number distribution around tube surface.