Difference between revisions of "TUGAS BESAR APLIKASI CFD: '''Two-Phase Simulation in Horizontal Flow Gas-Liquid Separator'''"

From ccitonlinewiki
Jump to: navigation, search
(Numerical Geometry)
(Validation)
Line 55: Line 55:
 
=== Validation ===
 
=== Validation ===
  
The simulation will be validated with the previous three-dimensional method by ___, compared to its efficiency and diverter distance from the inlet's system. A simulation, regardless of two-phases and boundary conditions, needs to be solved beforehand to achieve the mathematical solution. The geometry uses the one that has been investigated by ___ but in two-dimensional form. It is scaled down into 1:100 with 100 divisions in each axis (X and Y). Knowing the conditions in every control volume within a certain time is simulated in a transient state simulation. The fluid inside is assumed as incompressible air within subsonic speed around 5 m/s. Because it will cause a turbulent flow on a large scale, the Large Eddy Simulation (LES) method is implemented during the simulation. The height difference between the two outlets and the scaled-down geometry affected the outlets' dimensions' exact number. The pressure assumed is based on basic hydrodynamic pressure theoretical expression. The results were 0 Pa and 15.79 Pa, upper-pressure, and lower-pressure outlets, respectively. Based on the figure below shows the animation from the result of the simulation.
+
The simulation will be validated with the previous three-dimensional method by Bayraktar, et al. (2017), compared to its efficiency and diverter distance from the inlet's system. A simulation, regardless of two-phases and boundary conditions, needs to be solved beforehand to achieve the mathematical solution. The geometry uses the one that has been investigated by Efendioglu et al. (2014). It is scaled down into 1:100 with 100 divisions in each axis (X and Y). Knowing the conditions in every control volume within a certain time is simulated in a transient state simulation. The fluid inside is assumed as incompressible air within subsonic speed around 5 m/s. Because it will cause a turbulent flow on a large scale, the Large Eddy Simulation (LES) method is implemented during the simulation. The height difference between the two outlets and the scaled-down geometry affected the outlets' dimensions' exact number. The pressure assumed is based on basic hydrodynamic pressure theoretical expression. The results were 0 Pa and 15.79 Pa, upper-pressure, and lower-pressure outlets, respectively. Based on the figure below shows the animation from the result of the simulation.
  
 
[[File:Velmag.jpg|550px|thumb|center|'''Figure 3.''' Single-phase Assumption Velocity Magnitude]]
 
[[File:Velmag.jpg|550px|thumb|center|'''Figure 3.''' Single-phase Assumption Velocity Magnitude]]

Revision as of 22:16, 2 January 2021

Introduction

Petroleum reaches the surface as a mixture consisting of gas and fluid substance. To achieve an adequate quality of petroleum, one needs to satisfy the process of a petroleum refinery, which requires deliberation in multiphase separation. A gas-liquid separator was designed to separate two different substances using a diverter inside the system. To acquire efficient separation, one needs to consider the effective diverter near the system's inlet. This consideration requires a perilous investigation, which numerical modeling would be utilized in achieving the low cost and minimum risk investigation upon the system. In petroleum production, there are several types of separators. The separators are used based on the numbers of phases, crude oil properties, and separator conditions. These are vertical, horizontal, and spherical separators, which are widely used in production. Regarding the lowes cost expense in these separators, the horizontal separator has the lowest ones. This separator is considered as a gravity-based facility that was designed to provide sufficient time for droplets separation. The schematic flow direction of this system will be depicted below to ensure the simplicity of the system.

Figure 1. Horizontal Separator Inner Geometry and Flow Direction

Objectives

In this simulation, there will be various assumptions due to the model limitations. First of all, the model that will be simulated applies for a two-phase separator only. The real case in using the system would be in a three-phase consideration. Second, there would be numerous neglections since the simulation only focuses on the two-phase separation. There would be no other additional phase separators, such as coalescer, vortex breaker, or baffle, widely used in the actual system. The simulation will only focus on the inlet velocity and separator distance variation to acquire its effectiveness. For further objectives will be mentioned below:

1. To evaluate the system's effectiveness by comparing the previous simulation with the redesigned 3D simulation.

2. To investigate the most efficient separator within several distances from the inlet and various inlet velocities.

3. To investigate the suitable separator with two different inlet positions based on its effectiveness on both outlets.

Numerical Geometry

The geometry would be the same as the previous study by Efendioglu, A., et al. (2014), and the regulations on oil handling systems. For simplicity in simulation, the geometry would be in two-dimension, and the result's validation will be performed to achieve the similarities from the 3D simulation. The additional internal apparatuses would be neglected and only using the diverter considered in the simulation. This would point out each of the phase separations as perceptible as the post-processor can with acceptable information to a certain condition.

Figure 2. Horizontal Separator 3D Geometry

Methodology

Software

The numerical simulation will be using CFDSOF® (for the pre-processing and the processing step), the first Indonesian CFD software established by PT CCIT Group Indonesia, and ParaView as the post-processor of the simulation. ....

Mathematical Model (Verification)

The simulation was solved using the Reynolds averaged Navier-Stokes (RANS), k-ε turbulence model. In order to ease the visualization between phases, the multiphase eulerian method or Eulerian-Eulerian model is being implemented, which attributes separate momentum and continuity equations for each phase. ....

Boundary Conditions and Solver Control

....

Fluid Properties
Fluid Type Density Dynamic Viscosity Mass Flow Rate
Oil .. .. ..
Gas .. .. ..

Simulation Limitations

Regarding the simulation that brought various complexities upon the gas-liquid phase, the effects of gas flashing, foaming, emulsification, and in between phases interactions will be neglected. ....

Results and Discussions

Validation

The simulation will be validated with the previous three-dimensional method by Bayraktar, et al. (2017), compared to its efficiency and diverter distance from the inlet's system. A simulation, regardless of two-phases and boundary conditions, needs to be solved beforehand to achieve the mathematical solution. The geometry uses the one that has been investigated by Efendioglu et al. (2014). It is scaled down into 1:100 with 100 divisions in each axis (X and Y). Knowing the conditions in every control volume within a certain time is simulated in a transient state simulation. The fluid inside is assumed as incompressible air within subsonic speed around 5 m/s. Because it will cause a turbulent flow on a large scale, the Large Eddy Simulation (LES) method is implemented during the simulation. The height difference between the two outlets and the scaled-down geometry affected the outlets' dimensions' exact number. The pressure assumed is based on basic hydrodynamic pressure theoretical expression. The results were 0 Pa and 15.79 Pa, upper-pressure, and lower-pressure outlets, respectively. Based on the figure below shows the animation from the result of the simulation.

Figure 3. Single-phase Assumption Velocity Magnitude
Figure 4. Single-phase Assumption Pressure
Figure 5. Single-phase Assumption Graph from Lower to Upper Outlet

Based on these figures, they have shown that the simulation satisfies the theoretical expressions, although the flow inlet affects the magnitudes between them. The glyph feature from the Paraview post-processor shows the velocity vector that flows to both outlets. In contrast, the pressure magnitude shows that the bottom outlet receives a larger magnitude of the pressure. Because of the low kinematic viscosity and density, the flow reaches the turbulent region, which the LES method is suitable in calculating the eddies that occur. Provided that the grid-independent study has been investigated, the results will likely to gain more accurate results. To sum up, the single-phase simulation has fulfilled the theoretical expression, and using two-phase simulation is now suitable for the next step.

Figure 6. Single-phase Assumption Graph from Inlet until the Wall Near Upper Outlet

The velocity inlet, which was previously assumed to be 6 m/s, resulted in a fluctuating magnitude as the system's air travels. Based on the black line from the graph, the air fluctuates due to the gravity effect that occurs in the system. Figure 5 shows that as the air flows departed from the system, the velocity by far shows slightly constant results. Figure 3 also shows that the air affected by the gravitational force was also affected by the buoyancy force that occurred in the system. It is shown by the vectorial arrows that represent the air direction splits as the effect of two different forces. According to the graph, it sums up that the air travels sensibly, although the accuracy might not be the greatest due to the low numbers of mesh.

Conclusions

References

[1] Yayla, Sedat & Kamal, Karwan & Bayraktar, Seyfettin & Oruç, Mehmet. (2017). TWO PHASE FLOW SEPARATION IN A HORIZONTAL SEPARATOR BY INLET DIVERTER PLATE IN OILFIELD INDUSTRIES.

[2] Eissa, M., 2013. Influence of Flow Characteristics on the Design of Two-Phase Horizontal Separators. Journal of Engineering and Computer Science (JECS), 15(2), pp.50-62.

[3] Adeniyi, O., 2004. Development of Model and Simulation of a Two-Phase, Gas-Liquid Horizontal Separator. Leonardo Journal of Sciences, 3(5), pp.34-45.

[4] Kharoua, N., Khezzar, L. and Saadawi, H., 2013. CFD modelling of a horizontal three-phase separator: a population balance approach. American Journal of Fluid Dynamics, 3(4), pp.101-118.

[5] Wilkinson, D., Waldie, B., Nor, M.M. and Lee, H.Y., 2000. Baffle plate configurations to enhance separation in horizontal primary separators. Chemical Engineering Journal, 77(3), pp.221-226.

[6] Efendioglu, A., Mendez, J. and Turkoglu, H., 2014. The numerical analysis of the flow and separation efficiency of a two-phase horizontal oil-gas separator with an inlet diverter and perforated plates. Advances in Fluid Mechanics, 10, p.133.

[7] Stewart, M. and Arnold, K.E., 2011. Surface production operations, Volume 1: Design of oil handling systems and facilities (Vol. 1). Elsevier.