Evaluation of Flow Characteristics in an Oil-Water Separator Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Terry Potter ◽  
Tathagata Acharya
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Water Volume ◽  
Multiphase Model ◽  
Two Phase ◽  
Water Separator ◽  
Oil Water ◽  
Simulation Results ◽  
Water Cut

Abstract Multiphase separators on production platforms are among the first equipment through which well fluids flow. Based on functionality, multiphase separators can either be two-phase that separate oil from water, or three-phase that separate oil, natural gas, and water. Separator performances are often evaluated using mean residence time (MRT) of the hydrocarbon phase. MRT is defined as the amount of time a given phase stays inside the separator. On field, operators usually measure MRT as the ratio of active volume occupied by each phase to the phase volumetric flowrate. However, this method may involve significant errors as the oil-water interface height is obtained using level controllers and the volume occupied by each phase is calculated assuming the interface can be extrapolated from the weir back to the separator inlet. In this study, authors perform computational fluid dynamics (CFD) on a two-phase horizontal separator to evaluate MRT as a function of varying water volume flowrates (water-cut) in a mixture of water and oil. The authors use residence time distributions (RTD) to obtain MRT at each water-cut — a method that results in significantly more accurate results than the regular method used by operators. The numerical model is developed with commercial software package ANSYS Fluent. The code uses the Eulerian multiphase model along with the k-ε turbulence model. The simulation results show agreement with experiments performed by previous researchers. Additional simulations are performed to assess the effect of various separator internals on separator performance. Simulation results suggest that the model developed in this study can be used to predict performances of two-phase liquid-liquid separators with reasonable accuracy and will be useful towards their design to improve performances under various inlet flow conditions.

scholarly journals A CFD study on hydrocarbon mean residence time in a horizontal oil–water separator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Tathagata Acharya ◽  
Terry Potter
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Flow Characteristics ◽  
Two Phase ◽  
Primary Zone ◽  
Water Separator ◽  
Perforated Baffle ◽  
Oil Water ◽  
Dynamics Analyses ◽  
Throat Section

AbstractThis study presents computational fluid dynamics analyses on oil–water flow characteristics in a horizontal separator. The performance of these vessels are inferred from mean residence time and cumulative residence time distribution of the hydrocarbon phase inside the separator. The authors model a separator used by previous researchers and evaluate mean residence time of the hydrocarbon phase in a two-phase mixture of oil and water. Three different water-cuts of 21%, 32%, and 57% are used. Additional analyses are done to assess how certain geometric features of the separator influence hydrocarbon mean residence time. The results show that the addition of a second perforated baffle plate does not improve the hydrocarbon mean residence time significantly. However, introducing a downward slanting throat section between the primary zone and the gravity separation zone improves the hydrocarbon mean residence time at 21% and 32% water-cuts. The results suggest oil–water separators with a throat section may be more efficient than regular horizontal separators without the throat section at low water-cuts.

Modeling a New Rotational Reciprocating Plate Impeller Using Computational Fluid Dynamics

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Yun Lin ◽  
Jules Thibault ◽  
Zisheng Zhang
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Liquid Velocity ◽  
Fermentation Broth ◽  
Velocity Shear ◽  
Multiphase Model ◽  
Rushton Turbine ◽  
Simulation Results

A new impeller, the rotational reciprocating plate impeller (RRPI), designed to handle highly viscous fermentation broth, was modeled using computational fluid dynamics (CFD) to gain more insight into its performance. A standard Rushton turbine was first simulated using CFD software Fluent(r) for validation purposes. Under experimental conditions, the prediction of the power number obtained from CFD simulation agrees qualitatively with the experimental data. Multiphase simulation was used to better represent the gas-liquid interactions using Eulerian multiphase model. The rotational reciprocating movement of the RRPI was approximated using small time steps, each of which has a different rotation speed. Water and carboxymethyl cellulose (CMC) solutions were used as model fluids to represent the different stages of a typical fermentation with a rheologically-evolving broth. By comparing the simulation results to experimental data, the efficiency of the toothed belt used to drive the Rushton turbine impeller was confirmed to be high as expected, while the efficiency of the three-arm linkage system used to achieve the rotational reciprocation of the RRPI was estimated to be around 80%. The uniformity of mixing with the 3-Rushton impeller and the RRPI was compared to each other by investigating the distribution of liquid velocity, shear rate, and broth viscosity. The simulation results proved that the RRPI eliminated the dead zones that usually form when the Rushton turbines are used in viscous medium.

Computational Fluid Dynamics Modeling of Benjamin and Taylor Bubbles in Two-Phase Flow in Pipes

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
M. Ramdin ◽  
Ruud Henkes
Keyword(s):  
Fluid Dynamics ◽  
Surface Tension ◽  
Computational Fluid Dynamics ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Bubble Velocity ◽  
Multiphase Model ◽  
Dynamics Modeling ◽  
Two Phase ◽  
Eotvos Number

Abstract There is an increasing interest in applying three-dimensional computational fluid dynamics (CFD) for multiphase flow transport in pipelines, e.g., in the oil and gas industry. In this study, the volume of fluid (VOF) multiphase model in a commercial CFD code was used to benchmark the capabilities. Two basic flow structures, namely, the Benjamin bubble and the Taylor bubble, are considered. These two structures are closely related to the slug flow regime, which is a common flow pattern encountered in multiphase transport pipelines. After nondimensionalization, the scaled bubble velocity (Froude number) is only dependent on the Reynolds number and on the Eötvös number, which represent the effect of viscosity and surface tension, respectively. Simulations were made for a range of Reynolds numbers and Eötvös numbers (including the limits of vanishing viscosity and surface tension), and the results were compared with the existing experiments and analytical expressions. Overall, there is very good agreement. An exception is the simulation for the 2D Benjamin bubble at a low Eötvös number (i.e., large surface tension effect) which deviates from the experiments, even at a refined numerical grid.

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

scholarly journals Numerical Simulation and Analysis on Spray Drift Movement of Multirotor Plant Protection Unmanned Aerial Vehicle

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2399 ◽  
Author(s):  
Fengbo Yang ◽  
Xinyu Xue ◽  
Chen Cai ◽  
Zhu Sun ◽  
Qingqing Zhou
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Droplet Size ◽  
Wind Field ◽  
Flow Model ◽  
Two Phase Flow ◽  
Plant Protection ◽  
Three Dimensional ◽  
Phase Flow ◽  
Two Phase

In recent years, multirotor unmanned aerial vehicles (UAVs) have become more and more important in the field of plant protection in China. Multirotor unmanned plant protection UAVs have been widely used in vast plains, hills, mountains, and other regions, and become an integral part of China’s agricultural mechanization and modernization. The easy takeoff and landing performances of UAVs are urgently required for timely and effective spraying, especially in dispersed plots and hilly mountains. However, the unclearness of wind field distribution leads to more serious droplet drift problems. The drift and distribution of droplets, which depend on airflow distribution characteristics of UAVs and the droplet size of the nozzle, are directly related to the control effect of pesticide and crop growth in different growth periods. This paper proposes an approach to research the influence of the downwash and windward airflow on the motion distribution of droplet group for the SLK-5 six-rotor plant protection UAV. At first, based on the Navier-Stokes (N-S) equation and SST k–ε turbulence model, the three-dimensional wind field numerical model is established for a six-rotor plant protection UAV under 3 kg load condition. Droplet discrete phase is added to N-S equation, the momentum and energy equations are also corrected for continuous phase to establish a two-phase flow model, and a three-dimensional two-phase flow model is finally established for the six-rotor plant protection UAV. By comparing with the experiment, this paper verifies the feasibility and accuracy of a computational fluid dynamics (CFD) method in the calculation of wind field and spraying two-phase flow field. Analyses are carried out through the combination of computational fluid dynamics and radial basis neural network, and this paper, finally, discusses the influence of windward airflow and droplet size on the movement of droplet groups.

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