Gas-Liquid Cylindrical Cyclone Research Articles

Multi-objective optimization of a novel gas-liquid cylindrical cyclone based on response surface methodology

Currently, most major oilfields in China have reached a stage of high water content, where the extracted fluid is often accompanied by significant volumes of associated gas. This situation increases extraction costs and elevates safety risks. To address these challenges, this paper presents an innovative redesign of the traditional gas-liquid cylindrical cyclone (GLCC) by applying composite mechanics to improve the inner cone structure. The new design is tailored for conditions with high gas content and flow rates. Using response surface optimization, the optimal structural parameters for the separator were identified: an inlet area of 881 mm2, a column diameter of 110 mm, and an inner cone height of 189 mm. Furthermore, the study integrates numerical simulation with experimental research to compare and analyze the flow characteristics and separation performance of the GLCC before and after optimization. The results demonstrate that the optimized GLCC achieves a separation efficiency of 93.2 %, an improvement of 21.2 percentage points over the initial design, with a maximum pressure loss of 0.0621 MPa. The experimental findings and numerical simulations show strong agreement, confirming the efficacy of the new design.

Two-Stage Separate Flow Measurement System Based on Compact Gas–Liquid Cylindrical Cyclone and Electrical Resistance Tomography

Two-Stage Separate Flow Measurement System Based on Compact Gas–Liquid Cylindrical Cyclone and Electrical Resistance Tomography

Selecting the inlet configuration for gas-liquid cylindrical cyclone separator

Gas-Liquid Cylindrical Cyclone Separator (short for GLCC) is a compact separator that has been widely used in petroleum production. The inlet configuration has significant impact of the GLCC capacity separation. By utilization of both FEM simulation and practical experiments, three inlet configurations and twelve inclined angles are investigated to find the steadily operating inlet configuration for industrial applications. In this study, the flow pattern and kinematic behaviour of each configuration are thoroughly analysed. Besides, the distribution of three velocity components of the body flow in GLCC is compared with one of the practical experiments. The result shows that the current inclined-inlet angle of 27° is not the steadily operating angle for industrial applications. In steady, it is a range of inclined inlet angle from 0° to 35° for three inlet configurations. The dual-inlet configuration indicates better properties for separating efficiency.

Gas liquid cylindrical cyclone flow regime identification using machine learning combined with experimental mechanism explanation

The flow regimes of GLCC with horizon inlet and a vertical pipe are investigated in experiments, and the velocities and pressure drops data labeled by the corresponding flow regimes are collected. Combined with the flow regimes data of other GLCC positions from other literatures in existence, the gas and liquid superficial velocities and pressure drops are used as the input of the machine learning algorithms respectively which are applied to identify the flow regimes. The choosing of input data types takes the availability of data for practical industry fields into consideration, and the twelve machine learning algorithms are chosen from the classical and popular algorithms in the area of classification, including the typical ensemble models, SVM, KNN, Bayesian Model and MLP. The results of flow regimes identification show that gas and liquid superficial velocities are the ideal type of input data for the flow regimes identification by machine learning. Most of the ensemble models can identify the flow regimes of GLCC by gas and liquid velocities with the accuracy of 0.99 and more. For the pressure drops as the input of each algorithm, it is not the suitable as gas and liquid velocities, and only XGBoost and Bagging Tree can identify the GLCC flow regimes accurately. The success and confusion of each algorithm are analyzed and explained based on the experimental phenomena of flow regimes evolution processes, the flow regimes map, and the principles of algorithms. The applicability and feasibility of each algorithm according to different types of data for GLCC flow regimes identification are proposed.

Experimental and numerical study on the performance of a new dual-inlet gas–liquid cylindrical cyclone (GLCC) based on flow pattern conditioning

Gas-Liquid Cylindrical Cyclone (GLCC) is a compact and efficient separation device used in oil and gas separation field. A new dual-inlet GLCC which can change the flow area ratio was designed and examined. The liquid separation efficiencies under five flow area ratios were experimentally measured. The liquid film velocity distribution was measured by MATLAB PIVlab. The finite volume method (FVM) was used to discretize the control equations. The liquid film thickness, gas–liquid flow distribution ratio and liquid flow streamline were obtained. The simulated liquid film velocities were seen to be consistent with experimental observations. Experimental and simulation results showed that by changing the flow area ratio of the upper and lower inlet pipes, the flow distribution in the upper and lower inlet pipes changed, liquid entering the upper GLCC cylinder reduced, the liquid film tangential velocity near the lower inlet increased and the change of liquid film axial velocity tended to be stable. The new type of GLCC expanded the safe operational separation envelop (envelop of the no LCO).

Numerical simulation on gas–liquid separation characteristics in a GLCC‐horizontal combined separator

AbstractCurrently, computational fluid dynamics has become the primary method for analyzing the fluid flow state inside the machine. Herein, the Ansys Fluent software is used to design a more effective oil‐field device, namely, a gas–liquid cylindrical cyclone (GLCC)‐horizontal combined separator. The characteristics of gas–liquid mixed flow, fluid turbulence intensity, and phase volume fraction distribution are analyzed, and the factors affecting the gas–liquid separation efficiency are evaluated under various working conditions. The results show that low gas–liquid separation efficiencies are obtained at inlet liquid ratios (liquid proportion in fluid) of both 30% and 70% in GLCC. After the fluid enters the separator, the maximum level of turbulence in the collision area increases from 2.458 to 3.033 m2/s2 as the inlet liquid ratio is increased from 30% to 70%, with the generation of oil–water and gas–liquid stratification at the back. Furthermore, the maximum gas holdup in the liquid outlet increases from 7% to 12% to 25% as the liquid ratio is increased from 30% to 50% to 70%. With throttling at a liquid ratio of 70%, the maximum gas holdup is again close to 14%.

Numerical Analysis of Flow Characteristics of Upper Swirling Liquid Film Based on the Eulerian Wall Film Model

The Upper Swirling Liquid Film (USLF) phenomenon that occurs in the upper cylinder of the Gas–Liquid Cylindrical Cyclone (GLCC) separator is the direct cause of the low separation efficiency of the liquid phase. In this study, first, the USLF formation and development were simulated by an improved Eulerian-EWF coupled simulated method. By introducing a profile-defined inlet boundary and considering entrainment droplet size distributions, the Eulerian-EWF method got reasonable results which agreed well with the experimental. Then, the flow characteristics and changing laws of the USLF including film thickness, film axial velocity, and film tangential velocity were analyzed by this method under different gas–liquid flow rates. It suggested that the liquid film thickness often reaches a maximum at the aspect ratio (z-z0)/D=(1.2–3.9) above the tangential inlet, and the film thickness appears to be more sensitive to the gas flow than to the liquid flow. For the film axial velocity, the direction of film velocity on the front and back sides seems to be generally opposite. Finally, typical distributions of the aforementioned USLF variables were presented and corresponded accordingly, and two obvious rules were found. One is that the position where the thickest liquid film is located always corresponds to the position where the axial film velocity turns from positive to negative for the first time. The other is that the tangential film velocity has a strong synchronous relationship with the film thickness. This research might provide somewhat valid information for the future LCO-prevented measurement in GLCC separators.

Evaluation and Improvement of the Performance of a Wellhead Multistage Bundle Gas–Liquid Separator

A wellhead multistage bundle gas–liquid separator combining a gas–liquid cylindrical cyclone (GLCC) with multi-tube bundle components is expected to improve the gas–liquid separation performance. However, there is no unified understanding of the factors influencing the separation performance of the separator. The continuous improvement and applications of the separator are restricted. This paper evaluated the performance of the separator using a numerical simulation method. The results indicate that the separation flow field evolves to be uniform with the increased water cut when the gas–oil ratio and flow rate remain constant. Compared with a 30% water cut, the separation efficiency at a 50% water cut increased by 5.88%. When the gas–oil ratio and water cut remained constant, the swirl effect of the primary separation was enhanced. The separation efficiency increased to more than 70% when the flow rate was 15 m/s. When the flow rate and water cut remained unchanged, the pressure of the separation flow field was reduced. However, when the gas–oil ratio was greater than 160 m3/t, the flow field trace density of the secondary separation bundle was reduced, and the separation efficiency was also lower than 60%. The separation efficiency can be further improved by optimizing the number and diameter of secondary separation bundles.

Effects of pressure control on droplet size distribution and flow regimes in gas–liquid cylindrical cyclone

Marine production platforms and subsea production systems desperately need compact and highly efficient gas–liquid separators. The gas–liquid cylindrical cyclone (GLCC), which mainly utilizes gravitational and centrifugal forces to achieve separation, can be an superior choice. Herein, a pressure control scheme is proposed that allows the GLCC to realize fast and stable gas–liquid separation. The droplet size distributions measured by a Malvern RTSizer indicated that increasing the liquid superficial velocity only increased the distribution of small droplets at the inlet. The droplet size distribution of the down sampling at a high dimensionless pressure was larger than that at a low dimensionless pressure, which can be explained by the droplet migration model. As the dimensionless pressure decreased, four flow regimes were experimentally observed: annular flow, churn flow-stratified flow, falling droplets, and pure gas. Electrical resistance tomography measurement results indicated that better convergence of the bubbly filament was achieved at a higher dimensionless pressure.

A statistical method for flow pattern and efficiency prediction using pressure drop in a two-stage gas liquid cylindrical cyclone

An experimental investigation is conducted in a novel gas-liquid separator called Two-stage Gas Liquid Cylindrical Cyclone (TGLCC) with gas-liquid ratio of 25–600, which enables flow pattern observation and separation efficiency/pressure drop measurement. The experimental results show that three inlet flow patterns are observed in the vertical pipe before the TGLCC inlet, which are continuous flow, intermittent flow and annular flow. The presence of vertical pipe before inlet can affect the evolution process of inlet flow patterns, and both intermittent flow and continuous flow have 3 forms of evolution process. Based on the experimental results, a statistical method called box plot is used to characterize the pressure drop fluctuation for different flow pattern evolutions, including the maximum, minimum, percentiles, mean and median. Based on pressure drop data analysis relating to corresponding flow patterns, a statistical method of predicting flow patterns is proposed using 5 criteria obtained from the box plot analysis. For all experimental data, the prediction accuracy is 98%. Then the separation efficiencies of gas riser and drain pipe are analyzed, which is found to be heavily affected by flow pattern evolutions. Therefore, the statistical method is further used to predict the separation efficiency of TGLCC with accuracy of 93.4%.

Numerical Analysis of Flow Behavior in Gas–Liquid Cylindrical Cyclone (GLCC©) Separators With Inlet Design Modifications

Abstract The Gas–Liquid Cylindrical Cyclone (GLCC©) is a simple, compact, and low-cost separator, which provides an economically attractive alternative to conventional gravity-based separators over a wide range of applications. More than 6500 GLCC©’s have been installed in the field to date around the world over the past two decades. The GLCC© inlet section design is a key parameter, which is crucial for its performance and proper operation. The flow behavior in the GLCC© body is highly dependent on the fluid velocities generated at the reduced area nozzle inlet. An earlier study (Kolla et al., 2017, “Structural Integrity Analysis of GLCC© Separator Inlet,” ASME J. Energy Resour. Technol., 140(5), p. 052905) recommended design modifications to the inlet section, based on safety and structural robustness. It is important to ensure that these proposed configuration modifications do not adversely affect the flow behavior at the inlet and the overall performance of the GLCC©. This paper presents a numerical study utilizing specific GLCC© field applications working under three different case studies representing the flow entering the GLCC, separating light oil, steam flooded wells in Minas, Indonesia. Commercially available computational fluid dynamics (CFD) software is utilized to analyze the hydrodynamics of flow with the proposed modifications of the inlet section for GLCC© field applications.

Optimization of static defoaming structure in gas-liquid separator

ABSTRACT The foam generated in the CO2 flooding-produced fluids causes considerable oil and gas treatment problems, especially in the separation process. The foam in the gas-liquid separator is detrimental to the liquid level control and can also reduce the gas-liquid separating efficiency. To accelerate the defoaming process and increase the gas-liquid separating efficiency, different defoaming structures were evaluated and optimized experimentally within a horizontal separator with a gas-liquid cylindrical cyclone (GLCC) at the inlet. When the gas-phase flow is constant at 2 m3/h and the gas-liquid ratios are 0.4, 0.8, 1.2, 1.6, 2.0, and 2.4, the effects of the type, the quantity of defoaming baffles, and the spacing between defoaming baffles were investigated. The defoaming effect of the perforated folded baffle is better than that of the ordinary baffle and multi-cone baffle, reducing up to 11% of the time. With three defoaming baffles, the foam can be broken by sufficient interception and squeeze, and the defoaming effect is much better than a single baffle or two baffles, reducing up to 8% of the time. The relative increase of the defoaming distance is beneficial to the defoaming. Moreover, the defoaming effect of 120 mm spacing is better than 40 mm and 80 mm spacing, reducing up to 9% of the time.

Experimental and numerical performance study of a downward dual-inlet gas-liquid cylindrical cyclone (GLCC)

The overflow of liquid film in the upper cylinder of gas–liquid cylindrical cyclone (GLCC) is the main reason for poor liquid efficiency. Liquid film formation is directly related to the flow pattern in the inlet pipe and the short-circuit flow at the inlet nozzle. Aiming to improve GLCC performance, a type of dual-inlet GLCC with a downward branch inlet was designed and examined. With a conventional single-inlet GLCC for comparison, experimental study and numerical simulations were conducted on flow patterns of liquid film and separation efficiencies of the dual-inlet GLCC. The results showed that the dual-inlet configuration had a split-flow effect, which guided most of the feed liquid to the lower GLCC cylinder through the lower inlet, hence improving pre-separation and inhibiting the short-circuit flow of the upper inlet. This effect consequently reduced the liquid entering the upper GLCC cylinder and, therefore, expanded the operational envelope.

Measurement of thickness and analysis on flow characteristics of upper swirling liquid film in gas-liquid cylindrical cyclone

The gas-liquid cylindrical cyclone (GLCC) is a device used to separate gas from liquid in offshore or subsea oil and gas production systems. The liquid film swirling along the upper cylinder wall in the GLCC is referred to as “upper swirling liquid film” (USLF). The flow patterns of USLF have a great influence on GLCC’s separation performance. However, the dynamics of the gas-liquid flow in a GLCC, especially the USLF characteristics, have not been well understood. In this study, experiments were conducted to investigate flow characteristics of USLF in a GLCC. The range of gas and liquid Reynolds numbers, Reg and Rel, was 27,869 ≤ Reg ≤ 68,120 and 2,881 ≤ Rel ≤ 14,335 respectively. The USLF’s thickness was measured using button electrodes. The results showed that the liquid film became thinner after leaving the inlet and the circumferential fluctuation of the thickness was not significant. The gas-liquid velocities had significant influences on film thickness, which increased almost linearly as liquid velocity increased, while presented a roughly S-shaped distribution as gas velocity increased. The friction factors of GLCC were determined based on the measured liquid film thickness and pressure drop. Additionally, the USLF’s flow patterns include swirling annular flow and swirling churn flow. Finally, a judgment criterion for flow pattern transition was established under the minimum gas-liquid interfacial stress theory. The model could accurately predict the transition condition. This work may provide a basis for comprehensive understanding of USLF characteristics.

Swirling Flow Regimes and Gas Carry-Under in Gas–Liquid Cylindrical Cyclone Separator in a Separated Outlet Configuration

Abstract Gas carry-under (GCU) and the corresponding gas volume fraction (GVF) in the gas–liquid cylindrical cyclone (GLCC©)2 liquid outlet occurs even within its normal operational envelope (OPEN). Few studies are available on GLCC, GCU, and GVF, which have been carried out in a GLCC operated in a metering loop configuration. This study focuses on GLCC GCU and GVF in swirling flow under separated outlet configuration with active control, which increases the GLCC OPEN significantly. A state-of-the-art test facility is used to acquire extensive GCU and GVF data for both air–water and air–oil flow in a 3″ diameter GLCC. The GLCC is equipped with three sequential trap sections to measure the instantaneous GVF and gas evolution in its lower part below the inlet. Also, gas trap sections are installed in the GLCC liquid outlet leg to measure the overall time-averaged GCU and GVF. The extensive acquired data shed light on the complex flow behavior in the lower part of the GLCC and its effect on the GCU and GVF in the GLCC. Tangential wall jet impingement from the GLCC inlet is the cause of gas entrainment and swirling in the lower GLCC body. The swirling flow mechanisms in the lower part of the GLCC are identified, which affect the GCU and GVF. The liquid viscosity and surface tension also affect the results. The GCU and GVF in the GLCC liquid outlet reduce as the superficial liquid velocities are increased for both air–oil and air–water flows, whereby the superficial gas velocities do not have a significant effect. The GCU and GVF for air–water flow are three orders of magnitude lower as compared to the air–oil flow.

Experimental Study of Square Inlets Effect on the Performances of Gas–Liquid Cylindrical Cyclone Separators (GLCC)

In the gas-oil field, the gas-liquid cylindrical cyclone (GLCC) separator has potentially replaced the traditional separator that is used over the century. It is also interesting for petroleum companies in recent years because of the effect of the oil world price. However, the behavior of phases in the equipment is very rapid, complex, and unsteady, which may cause the difficulty of enhancing the performance of the separation phases. The much research demonstrates that the geometry and the number of the inlet is probably the most important factor that impacts directly to the performance of separation of phases of the device. The main goal of the research paper is to deeply understand the effect of different geometrical configurations of the square inlet on hydrodynamics and performances for two phases flow (air-water). Two different inlet configurations are constructed, namely: One square inlet with the gradually reduced nozzle and two symmetric square inlets with the gradually reduced nozzle. As a result, the separation efficiency of the device will be higher when using two symmetric inlets, and we suggest the application of two symmetric square inlets type that is the same angle of inclination and the area of the nozzle with the unique inlet configuration to improve separation efficiency in GLCC. Such an inlet structure leads to lower swirl intensity decay than one inlet configuration. It also creates a more axis-symmetric flow at the centerline, which would improve the uplift of air bubbles in the performance of GLCC. Besides, this study can be viewed as a padding step to optimizing the operative parameters of GLCC in further study.

Experimental study of circular inlets effect on the performances of Gas-Liquid Cylindrical Cyclone separators (GLCC)

The gas-liquid cylindrical cyclone (GLCC) separators is a fairly new technology for the oil and gas industry. The current GLCC separator, a potential alternative for the conventional one, was studied, developed, and patented by Chevron company and Tulsa University (USA). It is used for replacing the traditional separators that have been used over the last 100 years. In addition, it is significantly attracted to petroleum companies in recent years because of the effect of the oil world price. However, the behavior of phases in the instrument is very rapid, complex, and unsteady, which may cause the difficulty of enhancing the performance of the separation phases. The multiple recent research shows that the inlet geometry is probably the most critical element that influences directly to the performance of separation of phases. Though, so far, most of the studies of GLCC separator were limited with the one inlet model. The main target of the current study is to deeply understand the effect of different geometrical configurations of the circular inlet on performances of GLCC by the experimental method for two phases flow (gas-liquid). Two different inlet configurations are constructed, namely: One circular inlet and two symmetric circular inlets. As a result, we propose the use of two symmetric circular inlets to enhance separator efficiency because of their effects.

Influence of slug flow on flow fields in a gas–liquid cylindrical cyclone separator: A simulation study

A simulation method for slug flow based on the VOF multiphase flow model was implemented in ANSYS® Fluent via a user-defined function (UDF) and applied to the dissipation of liquid slugs in the inlet pipe of a gas–liquid cylindrical cyclone (GLCC) separator while varying the expanding diameter ratio and angle of inclination. The dissipation of liquid slug in inlet pipe is analyzed under different expanding diameter ratios and inclination angles. In the inlet pipe, it is found that increasing expanding diameter ratio and inclination angle can reduce the liquid slug stability and enhancing the effect of gravity, which is beneficial to slug flow dissipation. In the cylinder, increasing the expanding diameter ratio can significantly reduce the liquid carrying depth of the gas phase but result in a slightly increase of the gas content in the liquid phase space. Moreover, increasing the inclination angle results in a decrease in the carrying depth of liquid in the vapor phase, but enhances gas–liquid mixing and increases the gas-carrying depth in the liquid phase. Taking into consideration the dual effects of slug dissipation in the inlet pipe and carrying capacity of gas/liquid spaces in the cylinder, the optimal expanding diameter ratio and inclination angle values can be determined.

Selection of an optimizing inlet angle for the gas-liquid cylindrical cyclone separator on hydrokinetic behavior

Selection of an optimizing inlet angle for the gas-liquid cylindrical cyclone separator on hydrokinetic behavior

Breakup, Coalescence, and Migration Regularity of Bubbles under Gas–Liquid Swirling Flow in Gas–Liquid Cylindrical Cyclone

This study investigates the bubble behavior in the lower part of the gas–liquid cylindrical cyclone experimentally and numerically. Malvern RTsizer and electrical resistance tomography were used to determine bubble size distribution and void fraction distribution, respectively. A discrete phase model was used to simulate the swirling flow field characteristics. The results indicated that as the gas flow rate increased, the small and medium-sized bubbles initially broke up and subsequently coalesced, whereas as the liquid flow rate increased, they only tended to break up. The gas core narrowed as the gas and liquid flow rates increased. The optimal gas–liquid separation performance was achieved when the liquid level was near 0.82 m. The separation mechanism of bubbles was analyzed via experimental observations and the simulated flow field distribution. An effective mechanism model based on bubble migration analysis was developed to predict the critical diameter of bubbles that can be separated.