Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
권호 표지
DOI QR코드

DOI QR Code

Three-Phase Eulerian Computational Fluid Dynamics (CFD) of Air-Water-Oil Separator with Coalescer

유적 합체기가 포함된 공기-물-기름 분리 공정에 대한 3상 Eulerian 전산유체역학

  • Received : 2017.02.22
  • Accepted : 2017.03.13
  • Published : 2017.04.01
Download PDF
⟨ Previous Next ⟩

Abstract

Water is removed from crude oil containing water by using oil separator. This study aims to develop a three-dimensional (3D) Eulerian computational fluid dynamics (CFD) model to predict the separation efficiency of air-water-oil separator. In the incompressible, isothermal and unsteady-state CFD model, air is defined as continuous phase, and water and oil are given as dispersed phase. The momentum equation includes the drag force, lift force and resistance force of porous media. The standard k-${\varepsilon}$ model is used for turbulence flow. The exit pressures of water and oil play an important role in determining the liquid level of the oil separator. The exit pressures were identified to be 6.3 kPa and 5.1 kPa for water and oil, respectively, to keep a liquid level of 25 cm at a normal operating condition. The time evolution of volume fractions of air, water and oil was investigated. The settling velocities of water and oil along the longitudinal separator distance were analyzed, when the oil separator reached a steady-state. The oil separation efficiency obtained from the CFD model was 99.85%, which agreed well with experimental data. The relatively simple CFD model can be used for the modification of oil separator structure and finding optimal operating conditions.

물이 포함된 원유는 oil separator 를 거쳐 물이 제거된다. 본 연구의 목적은 공기-물-기름 3상 혼합물에 대한 3차원 oil separator 의 분리성능을 예측하기 위하여 Eulerian 전산유체역학(CFD: computational fluid dynamics) 모델을 개발하는 것이다. 비압축성, 등온, 비정상상태 CFD 모델식은 공기상을 연속상으로, 물과 기름상을 분산상으로 정의하며, 운동량 보존식은 항력(drag force), 양력(lift force), 다공성매체 저항력을 포함한다. 또한, 난류현상으로 standard k-${\varepsilon}$ 모델이 이용된다. 물과 기름 출구압은 oil separator 의 액위를 결정하는 중요한 인자이며, 정상운전상태 액위 25 cm를 맞추기 위하여 측정압은 각각 6.3 kPa, 5.1 kPa으로 결정되었다. 시간에 따른 공기, 물, 기름의 부피분율의 변화를 조사하였고, 정상상태에 도달하였을 때, 물과 기름상의 침강속도를 oil separator의 종축 길이에 따라 분석하였다. 본 연구에서 제시된 CFD 모델로부터 얻은 oil separator의 기름분리성능은 99.85%이며, 실험값과 거의 일치하였다. 비교적 단순한이 CFD 모델은향후 oil separator의구조를 변경하거나, 최적운전조건을 찾기위하여 유용하게사용될수있을 것이다.

Keywords

References

  1. Mohayeji, M., Farsi, M., Rahimpour, M. R. and Shariati, A., "Modeling and Operability Analysis of Water Separation from Crude Oil in an Industrial Gravitational Coalescer," J. Taiwan Inst. Chem. Eng., 60, 76-82(2016). https://doi.org/10.1016/j.jtice.2015.10.025
  2. Li, J. and Gu, Y., "Coalescence of Oil-in-Water Emulsions in Fibrous and Granular Beds," Sep. Purif. Technol., 42(1), 1-13 (2005). https://doi.org/10.1016/j.seppur.2004.05.006
  3. Zolfaghari, R., Fakhru'l-Razi, A., Abdullah, L. C., Elnashaie, S. S. E. H. and Pendashteh, A., "Demulsification Techniques of Water-in-Oil and Oil-in-Water Emulsions in Petroleum Industry," Sep. Purif. Technol., 170, 377-407(2016). https://doi.org/10.1016/j.seppur.2016.06.026
  4. Lu, H., Yang, Q., Xu, X. and Wang, H.-L., "Effect of the Mixed Oleophilic Fibrous Coalescer Geometry and the Operating Conditions on Oily Wastewater Separation," Chem. Eng. Technol., 39(2), 255-262(2016). https://doi.org/10.1002/ceat.201400773
  5. Mino, Y., Kagawa, Y., Matsuyama, H. and Ishigami, T., "Permeation of Oil-in-Water Emulsions through Coalescing Filter: Two-Dimensional Simulation Based on Phase-Field Model," AlChE J., 62(7), 2525-2532(2016). https://doi.org/10.1002/aic.15206
  6. Xie, W., Li, R., Lu, X., Han, P. and Gu, S., "Acoustically Aided Coalescence of Water Droplets and Dehydration of Crude Oil Emulsion," Korean J. Chem. Eng., 32(4), 643-649(2015). https://doi.org/10.1007/s11814-014-0253-6
  7. Kharoua, N., Khezzar, L. and Saadawi, H., "CFD Modelling of a Horizontal Three-Phase Separator: A Population Balance Approach," Amer. J. Fluid Dyn., 3(4), 101-118(2013).
  8. ACS, "Liquid-Liquid Coalescer Design Manual," ACS Industries, Houston(2014).
  9. Bansal, S., von Arnim, V., Stegmaier, T. and Planck, H., "Effect of Fibrous Filter Properties on the Oil-in-Water-Emulsion Separation and Filtration Performance," J. Hazard. Mater., 190(1-3), 45-50(2011). https://doi.org/10.1016/j.jhazmat.2011.01.134
  10. Lu, H., Yang, Q., Liu, S., Xie, L.-S. and Wang, H.-L., "Effect of Fibrous Coalescer Redispersion on W/O Emulsion Separation," Sep. Purif. Technol., 159, 50-56(2016). https://doi.org/10.1016/j.seppur.2015.12.049
  11. Shin, C. and Chase, G. G., "Water-in-Oil Coalescence in Micro-Nanofiber Composite Filters," AlChE J., 50(2), 343-350(2004). https://doi.org/10.1002/aic.10031
  12. Cai, X., Chen, J., Liu, M., Ji, Y. and An, S., "Numerical Studies on Dynamic Characteristics of Oil-Water Separation in Loop Flotation Column Using a Population Balance Model," Sep. Purif. Technol., 176, 134-144(2017). https://doi.org/10.1016/j.seppur.2016.12.002
  13. Lim, Y.-I., "State-of-Arts in Multiscale Simulation for Process Development," Korean Chem. Eng. Res., 51(1), 10-24(2013). https://doi.org/10.9713/kcer.2013.51.1.10
  14. Laleh, A. P., Svrcek, W. Y. and Monnery, W. D., "Design and CFD Studies of Multiphase Separators-a Review," Can. J. Chem. Eng., 90(6), 1547-1561(2012). https://doi.org/10.1002/cjce.20665
  15. Kim, B. J., Kim, S. Y., Roh, C. S. and Lee, Y. H., "A Study on the Flow Characteristics of Oil-Water Separator for Marine Ship CFD," Korean Fluid Mach. Assoc.: J. Fluid Mach., 19(4), 48-53(2016).
  16. Al-Yaari, M. A. and Abu-Sharkh, B. F., "CFD Simulation for Stratified Oil-Water Two-Phase Flow in a Horizontal Pipe," Asian Trans. Eng., 1(5), 68-75(2011).
  17. Kharoua, L., Khezzar, L. and Saadawi, H. N. H., "Application of CFD to Debottleneck Production Separators in a Major Oil Field in the Middle East," SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers, October 8-10, 2012, San Antonio, Texas, USA, pp. SPE-158201(2012).
  18. Kharoua, N., Khezzar, L. and Saadawi, H. N. H., "Using CFD to Model the Performance of Retrofit Production Separators in Abu Dhabi," SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers, October 8-10, 2012, San Antonio, Texas, USA, pp. SPE-161521(2012).
  19. Orciuch, W., Makowski, l., Moskal, A. and Gradon, L., "Evolution of the Droplet Size Distribution During a Two-Phase Flow through a Porous Media: Population Balance Studies," Chem. Eng. Sci., 68(1), 227-235(2012). https://doi.org/10.1016/j.ces.2011.09.034
  20. Tamayol, A. and Bahrami, M., "Transverse Permeability of Fibrous Porous Media," Proceedings of the 3rd International Conference on Porous Media and Its Applications in Science and Engineering (ICPM3), Engineering Conferences International, June 20-25, 2010, Montecatini, Italy, pp. 1-8(2010).
  21. Weber, L. J., Cherian, M. P., Allen, M. E. and Muste, M., Headloss Characteristics for Perforated Plates and Flat Bar Screesns, 1st ed., Iowa Institute of Hydraulic Engineering, The University of Iowa, Iowa(2000).
  22. Tomiyama, A., Tamai, H., Zun, I. and Hosokawa, S., "Transverse Migration of Single Bubbles in Simple Shear Flows," Chem. Eng. Sci., 57(11), 1849-1858(2002). https://doi.org/10.1016/S0009-2509(02)00085-4
  23. Frank, T., Shi, J. and Burns, A. D., "Validation of Eulerian Multiphase Flow Models for Nuclear Safety Applications," Third International Symposium on Two-Phase Flow Modeling and Experimentation, Assembly of World Conferences on Experimental Heat Transfer Fluid Mechanics and Thermodynamics, Sept. 22-24, 2004, Pisa, Italy(2004).
  24. Wang, L., Wang, L.-P., Guo, Z. and Mi, J., "Volume-Averaged Macroscopic Equation for Fluid Flow in Moving Porous Media," Int. J. Heat Mass Transfer, 82, 357-368(2015). https://doi.org/10.1016/j.ijheatmasstransfer.2014.11.056
  25. Vilagines, R. D. and Akhras, A. R., "Three-Phase Flows Simulation for Improving Design of Gravity Separation Vessels," SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers, September 19-22, 2010, Florence, Italy, pp. SPE-134090 (2010).
  26. Xiuli Wang and Economides, M., Advanced Natural Gas Engineering, 1st ed., Gulf Publishing Co., Houston(2009).