Session: 11-10-01: Multiphase Flow Applications

Paper Number: 165383

Optimal Design of Inlet Configuration for Improving Separation Efficiency in Free Water Knock Out Vessel 

In recent years, there has been a sharp increase in global demand for energy, whilst fossil fuels are becoming increasingly scarce. In response, countries with energy resources are increasingly weaponizing these assets, thereby rendering energy resources ever more important. As traditional fossil fuels are being depleted, there is a growing interest in unconventional energy resources, which include oil sands, shale gas and coalbed methane. Among these unconventional energy resources, oil sands are of particular interest as their estimated reserves are known to be approximately five times those of conventional petroleum reserves.

The extraction of oil from oil sands necessitates the assurance of fluidity. The high viscosity of oil sands, which are buried hundreds of meters underground, necessitates the injection of high-temperature and high-pressure steam to extract them to the ground. The extracted oil sands typically consist of sand, water, oil, and gas. In the initial processing stage, a desander device is used to remove sand, resulting in a bitumen emulsion composed of water, oil, and gas. Subsequently, the bitumen emulsion undergoes a phase separation process in the FWKO (Free Water Knockout) vessel utilizing density differences.

 The performance of this separation process is contingent upon the bitumen emulsion's residence time within the FWKO vessel. Residence time is defined as the duration for which the bitumen emulsion remains within the FWKO vessel, and the performance of the FWKO vessel is expressed in terms of separation efficiency. Various studies have been conducted to improve the separation efficiency of the FWKO vessel, primarily focusing on increasing residence time.

In this study, the optimization of the inlet configuration was undertaken to maximize FWKO performance. It was found that the incoming bitumen emulsion exhibited differences in turbulent kinetic energy depending on the configuration of the inlet device, which in turn led to variations in residence time and separation efficiency.

The numerical analysis was conducted using Fluent by ANSYS, and the turbulence model was selected as the most widely used k-ε realizable model in multiphase flow separation analysis due to its optimal computational cost and performance. The VOF (Volume of Fluid) model was selected for application in the simulation, given the necessity to consider the density difference of multiphase flow and to track the continuous interface during the gravity separation process. The FWKO pressure vessel model allows for steady-state analysis because the flow stabilizes over time and remains constant despite changes in time. Therefore, the pseudo-transient analysis method was applied.

After selecting the configuration with the optimal separation efficiency among the four different inlet configurations using numerical analysis techniques, a sensitivity analysis and optimization of the inlet location were carried out. The DOE (Design of Experiments) method was employed to establish the correlation between the design variables and the objective function, thereby deriving an efficient design point. The numerical analysis results indicated a variation of approximately 14%, contingent on the inlet shape, with the case exhibiting optimal performance demonstrating a separation efficiency of approximately 92%. The sensitivity analysis and optimization outcomes for the inlet and its that demonstrated the highest efficiency substantiated that the separation efficiency attained approximately 95% or more.

Presenting Author: Kyoung Hoon Chu Sungkyunkwan university

Presenting Author Biography: My name is Kyoung Hoon Chu and I have been now working for Sungkyunkwan University (SKKU) as a research professor since August 2022. For my Ph.D. degree, I studied various technologies for water and wastewater treatments. At University of South Carolina where I spent for my post-doc in the US, I worked on removal of natural organic matters/micropollutants in the surface water by adsorption, catalysis, and membrane filtration.
Currently, I am interested in multiphase flow of emulsion-type bitumen extracted from oil sands. In particular, I am trying to improve the existing phase separation process by improving the separation efficiency of the oil-water separator. Through this conference, I expect to contribute greatly to the oil plant industry by providing potential solutions for optimizing the separation system and improving operational efficiency.

Authors:

Hwan-Gyo Kim Sungkyunkwan university
Youn-Jea Kim +82-10-3032-7448
Kyoung Hoon Chu Sungkyunkwan university