Gas-Liquid Cylindrical Cyclone Separators Research Articles

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.

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.

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

Characterizing dynamics of swirling film in gas–liquid cylindrical cyclone separator using multi-scale entropy analysis

Gas–liquid cylindrical cyclone (GLCC) separator is attractive for subsea gas–water separation due to its simplicity and small footprint. In this study, we designed a multi-channel conductance probe and conducted an experiment of gas–liquid separation in a GLCC separator. Local information of the lower swirling liquid film in the GLCC is collected by the multi-channel conductance probe. To uncover the hydrodynamics of swirl liquid film in the lower part of the GLCC, multi-scale distribution entropy (MSDE) in coupled phase space is employed to analyze the multi-channel conductance signals. The results of the MSDE enable to indicate the spatial dynamics of the swirling film, which can provide beneficial insights for uncovering the generation mechanism of gas bubble in the process of gas carry-under.

The Effect of the Different Inlet's Structures of the Gas-Liquid Cylindrical Cyclone (GLCC) Separator

The inlet’s geometry is always the core factor that directly affects hydrodynamics and separation efficiency of the cyclone separation types. The Gas-Liquid Cylindrical Cyclone (GLCC) separators have been developed in recent years to separate into single phases of multiphase mixtures in the oil and gas industry. It is used to substitute for the traditional separator that is used over 100 years. However, the action of phases in the instrument is very fast, complicated and unsteady which may cause the difficulty to enhance the performance of the separation phases. Besides, the effect of inlet’s structures over its hydrodynamics and performance is not fully understood. The target of this study is to use experimental modeling for two phases flow (gas-water) to evaluate the effect of inlet geometrical modifications in the reduction of liquid carry-over (LCO). Four different inlet configurations are constructed, namely: One circular inlet, two symmetric circular inlets, one square inlet and two symmetric square inlets with the gradually reduced nozzle. From the results presented in this work, we propose the use of two symmetric inlets to enhance the separator efficiency because of their effects.

A Study of Flow Regimes in the Upper Part of a Compact Gas-liquid Separator

In the offshore oil and gas environment, there is usually the challenge with regards to available space offshore platforms for equipment installation; hence, compact separators are more attractive due to their small footprint. Also, in subsea oil and gas production, compact separators are attractive because of their light weight and ease of installation. A good understanding of the flow regimes in the upper part of the separator is essential for a robust design and operation. The performance of gas-liquid compact separator in terms of liquid carryover (LCO) and pressure drop depends on the type of flow regime in the upper part of the separator. However, there is a lack of experimental data on flow regimes in the upper part gas-liquid cyclone separators. In this research, data on flow regimes in the upper part of a 1.5-inch horizontal-inlet gas-liquid cylindrical cyclone separator was acquired using electrical resistance Tomography (ERT), wire mesh sensor (WMS), pressure transducer and visual observation. Based on flow imagining, observations and statistical analysis, the flow regimes were classified as swirling-annular, light-mist, heavy-mist and churn flow. A flow regime map for the separator was proposed based on a modified liquid and gas-Froude number. The work would be a useful guide to process engineers during the preliminary design and sizing of separators with similar geometry configuration.

Influence of inlet angle on flow pattern and performance of gas-liquid cylindrical cyclone separator

ABSTRACTGas-liquid cylindrical cyclone (GLCC) separator is widely used in the petroleum industry with potential field applications. Its performance is strongly influenced by the inlet configuration. The 27° optimal inclined inlet angle has been experimentally observed for GLCC with the same diameter of body and inlet. For other GLCCs, the effect of inlet angle on flow pattern and their performances have not been investigated. The main target of the current study is to deeply understand the changes of flow pattern with respect to different inclined angles and flow conditions. Twelve GLCCs with different inclined angles were numerically investigated by using the Reynold stress turbulence model to predict the flow pattern with GLCC. The distribution of radial, axial, and tangential velocity profiles and their maximum magnitudes with respect to the change of inlet angle were carefully considered in this study.

Dispersed two-phase flow in a gas–liquid cylindrical cyclone separator

The performance of a gas–liquid cylindrical cyclone separator for the separation of air bubbles from hydraulic fluid has been analyzed numerically using the commercial computational fluid dynamics flow solver CFX. Two-phase flow behavior is modeled based on an Eulerian–Eulerian approach, representing both liquid and dispersed gas phase as interpenetrating media with interphase momentum transfer captured based on existing bubble drag models. Only a single bubble size is considered for the dispersed phase and bubble coalescence is ignored. At the tangential inlet, a homogeneous gas– liquid mixture is assumed with specified mass flow and air/liquid volume fractions. Pressure conditions were imposed at both the upper gas outlet and the lower liquid outlet boundaries. Effect of changes in turbulence model and bubble drag model on analysis predictions was analyzed for selected operating conditions, that is, bubble sizes, air/liquid volume fractions and flow rates. Separation efficiency was high only for larger bubble sizes (100 mm) and high flow rates (250 L/min). For bubble sizes below 35 mm, the cyclone was ineffective. At high flow rates, cyclone performance suffers due to liquid carry over in the form of a swirling liquid wall film carried with the gas (bubble) phase through the top outlet. The Explicit Algebraic Reynolds Stress Turbulence Model together with the Grace Drag Model was found to be effective in exploring changes to the cyclone geometry. Here, improvements in separation efficiency were only achieved with significantly increased tangential velocities as a consequences of a reduced inlet port cross section. Predicted bubble size separation limits as a function of Reynolds number and axial-to-tangential velocity ratios were found to compare favorably with existing literature.

Hydrodynamics and velocity measurements in gas–liquid swirling flows in cylindrical cyclones

The gas–liquid swirl flow in a gas–liquid cylindrical cyclone separator has been characterized first qualitatively by flow visualizations. The emerged findings were then confirmed quantitatively by Laser Doppler Velocimetry measurements. The vortex core presents a very complex hydrodynamics, characterized by an alternation between a laminar and a turbulent state. The laminar regime is associated with velocities pointing in the same direction as the mean flow, while the turbulent state induces velocities in the opposite direction, i.e. a flow reversal. These observations give a first understanding of the origin of the double flow reversal regime that is encountered in swirl flows. It is shown that this flow structure appears for high swirl intensities, and results from a frequent laminarization of the vortex core. Results show that, contrary to the commonly assumed hypothesis, this flow structure is associated with good separation performance of the cyclone. Accordingly, we propose the use of multiple tangential inlets to generate the swirl motion in the cyclone, which is supposed to favor the double flow reversal regime, and thus, improve the separation efficiency.

On the effect of the nozzle design on the performances of gas–liquid cylindrical cyclone separators

This paper constitutes an experimental study of the separation performances of a gas–liquid cylindrical cyclone (GLCC) separator that interests the oil industry. The global hydrodynamics behavior in the GLCC is characterized by flow visualization under various inflow operating conditions. The effect of the inlet nozzle design on the performances of the separator is studied by using three different nozzles, and it proves to be a key parameter. With an insufficient nozzle restriction, low swirl intensity is imparted to the flow. Due to inadequate centrifugal effects, liquid is prematurely carried over by the gas as flooding occurs in the separator upper part. High amounts of gas are also carried under by the liquid stream. On the other hand, with a too severe nozzle convergence, the important drag applied by the gas leads to liquid “short circuiting” the cyclone toward the gas outlet. In addition to the nozzle design, the separator performances are influenced by phenomena such as liquid bridging or the occurrence of the slug flow regime at the cyclone inlet. This paper leads to a better understanding of the links between the hydrodynamics in the GLCC and its operational limits, which is necessary to enable reliable scaling up tools.

Wet Gas Separation in Gas-Liquid Cylindrical Cyclone Separator

A novel gas-liquid cylindrical cyclone (GLCC©, ©The University of Tulsa, 1994), equipped with an annular film extractor (AFE), for wet gas applications has been developed and studied experimentally and theoretically. Detailed experimental investigation of the modified GLCC has been carried out for low and high pressure conditions. The results show expansion of the operational envelope for liquid carry-over and improved performance of the modified GLCC. For low pressures, the modified GLCC can remove all the liquid from the gas stream, resulting in zero liquid carry-over (separation efficiency=100%). For high pressure conditions, the GLCC with a single AFE has separation efficiency >80% for gas velocity ratio, vsg/vann≤3. A mechanistic model and an aspect ratio design model for the modified GLCC have been developed, including the analysis of the AFE. The model predictions agree with the experimental data within ±15% for low pressure and ±25% for high pressure conditions.

Effect of the Inlet Geometry on the Flow in a Cylindrical Cyclone Separator

AbstractThe use of Gas-Liquid Cylindrical Cyclone (GLLC©) separators for gas-liquid separation is a new technology for oil and gas industry. Consequently, it is important to understand the flow behavior in the GLLC© and the effect of different geometrical geometries to enhance separation. The main objective of this study is to address the effect of different inlet geometries on the flow behavior in the GLLC© by measuring velocity components and the sum of the axial and tangential velocity fluctuations inside the GLLC© using a Laser Doppler Velocimeter (LDV). Three different inlet geometries were considered, namely, one inclined inlet, two inclined inlets, and a gradually reduced inlet nozzle. Axial and tangential velocities and turbulent intensities across the GLLC© diameter were measured at 24 different axial locations (318-900mm below the inlet) for each inlet geometry. Flow rates of 0.00454 and 0.00063m3∕s were selected to investigate the effect of flowrate (Reynolds number) on the flow behavior. Color contour maps color contour plots of axial and tangential velocity and the sum of the axial and tangential velocity fluctuations revealed some remarkable details of the flow behavior.

Local Velocity Measurements and Computational Fluid Dynamics (CFD) Simulations of Swirling Flow in a Cylindrical Cyclone Separator

Local measurements and 3D CFD simulations in gas-liquid cylindrical cyclone separators are scarce. The main objective of this study is to conduct local measurements and 3D CFD simulations to understand the swirling flow behavior in a cylindrical cyclone with one inclined tangential inlet. Axial and tangential velocities and turbulent kinetic energy across the cylinder diameter ID=0.089m were measured at 24 different axial locations (0.32–0.90 m below the inlet) by using a laser Doppler velocimeter (LDV). The liquid flow rate was 16.4m3/h, which corresponds to an average axial velocity of 0.732 m/s and Reynolds number of 66,900. Measurements are used to create color contour plots of axial and tangential velocity and turbulent kinetic energy. Color contour maps revealed details of the flow behavior. Additionally, 3D CFD simulations with different turbulence models are conducted. Simulations results are compared to LDV measurements.

Gas-Liquid Cylindrical Cyclone (GLCC©) Compact Separators For Wet Gas Applications

Gas-Liquid Cylindrical Cyclone (GLCC©1) separators are becoming increasingly popular as attractive alternatives to conventional separators as they are simple, compact, less expensive, have low-weight, and require little maintenance. However, present studies focus on GLCC designs and applications at relatively lower gas velocities (below the minimum velocity for onset of liquid carry-over in the form of annular/mist flow). With appropriate modifications, GLCCs can be used for wet gas (high gas liquid ratio, GLR) applications, characterized by higher gas velocities, to knock out the liquid droplets from the gas core. The objectives of this study are to design a novel GLCC capable of separating liquid from a wet gas stream; conduct experimental investigations to evaluate the GLCC performance improvement in terms of operational envelope for liquid carry-over; and, quantify the liquid extraction from the gas stream. GLCC design considerations/guidelines for wet gas application are also provided based on the experimental studies at low pressures. This investigation extends the capabilities of compact separators for wet gas applications for insitu gas volume fraction (GVF) greater than 95%.

Computational Fluid Dynamics (CFD) Study of Bubble Carry-Under in Gas-Liquid Cylindrical Cyclone Separators

Summary The gas-liquid cylindrical cyclone (GLCC©) separator is an attractive compact separator alternative to the conventional vessel-type separator. Thus, it is important to develop predictive tools for design and to be able to improve the technology of the GLCC. Previous studies on the GLCC have focused on mechanistic models capable of predicting the operational envelope for liquid carryover and on the understanding of the flow field in the GLCC. The main objective of this work was to investigate the behavior of small gas bubbles in the lower part of the GLCC, below the inlet, and the related gas carry-under phenomena. This investigation was performed by flow visualization and by using a commercially available computational fluid dynamics (CFD) code. Simulations of single-phase and two-phase flows were carried out and bubble trajectories were obtained in an axisymmetric geometry that represents the GLCC configuration. Bubble trajectory analysis was used to quantify the effects of the important parameters on bubble carry-under. These include bubble size, ratio of the GLCC length below the inlet to diameter, viscosity, Reynolds number, and inlet tangential velocity.

Performance Improvement of Gas Liquid Cylindrical Cyclone Separators Using Integrated Level and Pressure Control Systems

The performance of gas-liquid cylindrical cyclone (GLCC©) separators for two-phase flow metering loop can be improved by eliminating liquid overflow into the gas leg or gas blow-out through the liquid leg, utilizing suitable integrated control systems. In this study, a new integrated control system has been developed for the GLCC, in which the control is achieved by a liquid control valve in the liquid discharge line and a gas control valve in the gas discharge line. Simulation studies demonstrate that the integrated level and pressure control system is highly desirable for slugging conditions. This strategy will enable the GLCC to operate at constant pressure so as not to restrict well flow and simultaneously prevent liquid carry-over and gas carry-under. Detailed experimental studies have been conducted to evaluate the improvement in the GLCC operational envelope for liquid carry-over with the integrated level and pressure control system. The results demonstrate that the GLCC equipped with integrated control system is capable of controlling the liquid level and GLCC pressure for a wide range of flow conditions. The experimental results also show that the operational envelope for liquid carry-over is improved twofold at higher liquid flow rate region and higher gas flow rate region. GLCC performance is also evaluated by measuring the operational envelope for onset of gas carry-under. [S0195-0738(00)00804-9]