Numerical Study of Transient Flow and the Influence of Height and Viscosity in a Cyclonic Chamber in a Distribution System

2017 ◽  
Author(s):  
Carolina C. Rodrigues ◽  
Henrique K. Eidt ◽  
Rafael Dunaiski ◽  
César Y. Ofuchi ◽  
Flávio Neves ◽  
...  
Keyword(s):  
Distribution System ◽  
Transient Flow ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Petroleum Industry ◽  
Wire Mesh ◽  
Intermittent Flow ◽  
Transient Effects ◽  
Centrifugal Pumps ◽  
The Stability

In the petroleum industry, during the production and transportation of oil, multiphase flow occurs, due to the usual mixture of the crude oil, water and gas. This type of flow can be simplified, for study purposes, as a two-phase one, in which the gas is one phase, and a mixture of oil and water is the other. Separation of gaseous and liquid phases at the wellhead level is done by a separator and has innumerous advantages, including avoiding or at least reducing typical problems of multiphase flows such as intermittent flow, severe slugging and hydrates deposition. Another advantage is to increase the efficiency of the submersible centrifugal pumps or other artificial lift process used. A recurrent problem found in exploration and production of oil and gas is the range of the fluid viscosities encountered during exploration and extraction of petroleum, which can greatly vary with the temperature or the composition of the oil being extracted. Thus, it is necessary to understand how this parameter affects the performance of the equipment used. In addition, installation and maintenance of separators are hampered by the large size of this type of equipment. Therefore, a prior distribution system is here proposed, aiming to distribute the flow in more than one branch, in order to decrease the general size of the separation equipment needed, while maintaining the flow rate and separation efficiency. This distribution system has a cyclonic chamber, in which the flow enters through two nozzles tangentially oriented with the wall of the chamber, which performs a pre-separation due to the centrifugal field, and divides the flow into four outlets. This work presents a numerical study on the height influence of the cyclonic chamber in a distribution system. The transient beginning of the flow is analyzed, with the stability of the film being study. This work is focused on the behavior of the liquid phase in this proposed distribution system, so that only single-phase liquid flow at the inlet of the distribution system is considered. A validation was done through comparison with experimental data obtained in a test rig, in which was used one wire mesh sensor with 12 wires in order to evaluate the thickness of the liquid film over time. In addition, different heights and viscosities are studied in order to evaluate their influence on the flow. The parameters investigated are the film thickness, velocity and turbulence kinetic energy fields and flow rates at the outlets, focusing on the stability of the film and the transient effects associated with the beginning of the flow. In order to perform this study, the commercial software ANSYS-CFX 15.0 was used, with a hybrid mesh, for four different heights and two inlet velocities.

CRITICAL REVIEW OF EMULSION STABILITY AND CHARACTERIZATION TECHNIQUES IN OIL PROCESSING

2021 ◽  
pp. 1-36
Author(s):  
Vahideh Angardi ◽  
Ali Ettehadi ◽  
Özgün Yücel
Keyword(s):  
Separation Efficiency ◽  
Petroleum Industry ◽  
Cost Effective ◽  
Downstream Processing ◽  
Physical Factors ◽  
Comprehensive Review ◽  
Factors Affecting ◽  
Mathematical Explanations ◽  
The Stability ◽  
The Right

Abstract Effective separation of water and oil dispersions is considered a critical step in the determination of technical and economic success in the petroleum industry over the years. Moreover, a deeper understanding of the emulsification process and different affected parameters is essential for cost-effective oil production, transportation, and downstream processing. Numerous studies conducted on the concept of dispersion characterization indicate the importance of this concept, which deserves attention by the scientific community. Therefore, a comprehensive review study with critical analysis on significant concepts will help readers follow them easily. This study is a comprehensive review of the concept of dispersion characterization and conducted studies recently published. The main purposes of this review are to 1) Highlight flaws, 2) Outline gaps and weaknesses, 3) Address conflicts, 4) Prevent duplication of effort, 5) List factors affecting dispersion. It was found that the separation efficiency and stability of dispersions are affected by different chemical and physical factors. Factors affecting the stability of the emulsions have been studied in detail and will help to look for the right action to ensure stable emulsions. In addition, methods of ensuring stability, especially coalescence are highlighted, and coalescence mathematical explanations of phenomena are presented.

scholarly journals Numerical Study of the Winter–Kennedy Flow Measurement Method in Transient Flows

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1310
Author(s):  
Binaya Baidar ◽  
Jonathan Nicolle ◽  
Bhupendra K. Gandhi ◽  
Michel J. Cervantes
Keyword(s):  
Flow Rate ◽  
Transient Flow ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Cross Sectional ◽  
Transient Flows ◽  
Sectional Plane ◽  
The Stability ◽  
Opening And Closing ◽  
Spiral Casing

This paper explores the possibility of using the Winter–Kennedy (WK) method for transient flow rate measurement in hydraulic turbines. Computational fluid dynamic (CFD) analysis of a numerical model of an axial turbine was carried out for accelerating and decelerating flows. Those were obtained by linearly opening and closing of the guide vanes, respectively, while retaining the inlet pressure constant during the simulations. The behavior of several WK configurations on a cross-sectional plane and along the azimuthal direction of the spiral casing was studied during the transients. The study showed that there are certain WK configurations that are more stable than others. The physical mechanism behind the stability (or instability) of the WK method during transients is presented. Using the steady WK coefficient obtained at the best efficiency point (BEP), the WK method could estimate the transient flow rate with a deviation of about 7.5% and 3.5%, for accelerating and decelerating flow, respectively.

Determining the Norton’s Equivalent Model of Distribution System with Distributed Generation (DG) for Stability Analysis

2019 ◽  
Vol 12 (2) ◽  
pp. 190-198
Author(s):  
Sunny Katyara ◽  
Lukasz Staszewski ◽  
Faheem Akhtar Chachar
Keyword(s):  
Distributed Generation ◽  
Normal Condition ◽  
Distribution System ◽  
Distribution Networks ◽  
Equivalent Model ◽  
Stability Factor ◽  
Matlab Simulation ◽  
The Stability ◽  
Stability Issues

Background: Since the distribution networks are passive until Distributed Generation (DG) is not being installed into them, the stability issues occur in the distribution system after the integration of DG. Methods: In order to assure the simplicity during the calculations, many approximations have been proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle, more efficiently and accurately. This research presents an algorithm for finding the Norton’s equivalent model of distribution system with DG, considering from receiving end. Norton’s model of distribution system can be determined either from its complete configuration or through an algorithm using system’s voltage and current profiles. The algorithm involves the determination of derivative of apparent power against the current (dS/dIL) of the system. Results: This work also verifies the accuracy of proposed algorithm according to the relative variations in the phase angle of system’s impedance. This research also considers the varying states of distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated accordingly. Conclusion: The efficacy of the proposed algorithm is verified through MATLAB simulation results under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability factor was higher than 1 and the value of dS/dIL was away from 0.

scholarly journals Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1233
Author(s):  
Umair Jamil Ur Rahman ◽  
Artur Krzysztof Pozarlik ◽  
Thomas Tourneur ◽  
Axel de Broqueville ◽  
Juray De Wilde ◽  
...  
Keyword(s):  
Spray Drying ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Three Dimensional ◽  
Droplet Size Distribution ◽  
Vortex Chamber ◽  
Temperature Pattern ◽  
Multiphase Model ◽  
Drying Technology

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 µm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 µm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology.

A numerical study on combined baffles quick-separation device

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ehsan Dehdarinejad ◽  
Morteza Bayareh ◽  
Mahmud Ashrafizaadeh
Keyword(s):  
Turbulent Flows ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Turbulence Models ◽  
Complete Separation ◽  
Solid Particles ◽  
Flow Rates ◽  
Separation Device ◽  
Coupling Technique ◽  
Laminar And Turbulent Flows

Abstract The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.

A Numerical Study of the Flow Characteristics and Separation Efficiency of a Hydrocyclone

2018 ◽  
Vol 22 (11) ◽  
pp. 4272-4281 ◽  
Author(s):  
Ik-Tae Im ◽  
Gyu Dong Gwak ◽  
Se Min Kim ◽  
Young Ki Park
Keyword(s):  
Separation Efficiency ◽  
Numerical Study ◽  
Flow Characteristics

A Study of the Lateral Stability of Railroad Vehicles Using a Nonlinear Constrained Multibody Formulation

2001 ◽  
Author(s):  
Davide Valtorta ◽  
Khaled E. Zaazaa ◽  
Ahmed A. Shabana ◽  
Jalil R. Sany
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Theory ◽  
Linear Stability Analysis ◽  
Numerical Study ◽  
Operating Conditions ◽  
Lateral Stability ◽  
Railroad Vehicles ◽  
Contact Formulation ◽  
The Stability

Abstract The lateral stability of railroad vehicles travelling on tangent tracks is one of the important problems that has been the subject of extensive research since the nineteenth century. Early detailed studies of this problem in the twentieth century are the work of Carter and Rocard on the stability of locomotives. The linear theory for the lateral stability analysis has been extensively used in the past and can give good results under certain operating conditions. In this paper, the results obtained using a linear stability analysis are compared with the results obtained using a general nonlinear multibody methodology. In the linear stability analysis, the sources of the instability are investigated using Liapunov’s linear theory and the eigenvalue analysis for a simple wheelset model on a tangent track. The effects of the stiffness of the primary and secondary suspensions on the stability results are investigated. The results obtained for the simple model using the linear approach are compared with the results obtained using a new nonlinear multibody based constrained wheel/rail contact formulation. This comparative numerical study can be used to validate the use of the constrained wheel/rail contact formulation in the study of lateral stability. Similar studies can be used in the future to define the limitations of the linear theory under general operating conditions.

scholarly journals Mutual inductance instability of the tip vortices behind a wind turbine

2014 ◽  
Vol 755 ◽  
pp. 705-731 ◽  
Author(s):  
Sasan Sarmast ◽  
Reza Dadfar ◽  
Robert F. Mikkelsen ◽  
Philipp Schlatter ◽  
Stefan Ivanell ◽  
...  
Keyword(s):  
Growth Rate ◽  
Wind Turbine ◽  
Numerical Study ◽  
Operating Conditions ◽  
Analytical Relationship ◽  
Dynamic Mode ◽  
Spatial Structures ◽  
Tip Vortices ◽  
Positive Growth ◽  
The Stability

AbstractTwo modal decomposition techniques are employed to analyse the stability of wind turbine wakes. A numerical study on a single wind turbine wake is carried out focusing on the instability onset of the trailing tip vortices shed from the turbine blades. The numerical model is based on large-eddy simulations (LES) of the Navier–Stokes equations using the actuator line (ACL) method to simulate the wake behind the Tjæreborg wind turbine. The wake is perturbed by low-amplitude excitation sources located in the neighbourhood of the tip spirals. The amplification of the waves travelling along the spiral triggers instabilities, leading to breakdown of the wake. Based on the grid configurations and the type of excitations, two basic flow cases, symmetric and asymmetric, are identified. In the symmetric setup, we impose a 120° symmetry condition in the dynamics of the flow and in the asymmetric setup we calculate the full 360° wake. Different cases are subsequently analysed using dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD). The results reveal that the main instability mechanism is dispersive and that the modal growth in the symmetric setup arises only for some specific frequencies and spatial structures, e.g. two dominant groups of modes with positive growth (spatial structures) are identified, while breaking the symmetry reveals that almost all the modes have positive growth rate. In both setups, the most unstable modes have a non-dimensional spatial growth rate close to $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\pi /2$ and they are characterized by an out-of-phase displacement of successive helix turns leading to local vortex pairing. The present results indicate that the asymmetric case is crucial to study, as the stability characteristics of the flow change significantly compared to the symmetric configurations. Based on the constant non-dimensional growth rate of disturbances, we derive a new analytical relationship between the length of the wake up to the turbulent breakdown and the operating conditions of a wind turbine.

Numerical and Experimental Analysis of a Hybrid Wind-Wave Offshore Floating Platform’s Hull

2018 ◽  
Author(s):  
Thiago S. Hallak ◽  
José F. Gaspar ◽  
Mojtaba Kamarlouei ◽  
Miguel Calvário ◽  
Mário J. G. C. Mendes ◽  
...  
Keyword(s):  
Wave Energy ◽  
Experimental Analysis ◽  
Wind Wave ◽  
Numerical Study ◽  
Energy Devices ◽  
Wave Energy Converters ◽  
Wave Basin ◽  
Hybrid Concept ◽  
Point Absorbers ◽  
The Stability

This paper presents a study regarding a novel hybrid concept for both wind and wave energy offshore. The concept resembles a semi-submersible wind platform with a larger number of columns. Wave Energy Devices such as point absorbers are to be displayed around the unit, capturing wave energy while heaving and also enhancing the stability of the platform. In this paper, a first numerical study of the platform’s hull, without Wave Energy Converters, is carried out. Experiments in wave basin regarding the same unit have been conducted and the results are presented and compared to the numerical ones. Both stability and seakeeping performances are assessed and compared.

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