# Modeling of Demulsification Process of Crude Oil Emulsions from Wastewater of Desalination Plant

Document Type : Research Article

Authors

Department of Chemical, Petroleum and Gas Engineering, Shiraz University of Technology, Shiraz, I.R. IRAN

Abstract

The crude oil contains various contaminants including water, gas and sediments which should be removed in desalination unit. In addition, the wastewater from desalination unit should be refined to remove the oil droplets. In this work, a mathematical model was presented for demulsification process of crude oil emulsions from wastewater of desalination plant. A nonlinear hyperbolic integral differential equation was obtained by population balance method. The population balance integral equation terms were simplified using fixed pivot method and a system of partial differential equation (PDE) were obtained. The partial equations were converted into systems of ordinary differential equations (ODE) using the method of line. The ODEs were solved by the application of MATLAB Software. The profile of volumetric distribution of oil droplets, mean droplet diameter (D4,3), and oil separation rate along the height of the system at different times were reported. The accuracy of the model was examined by comparing with experimental data of water dispersion in oil system obtained from literature. Then, the model was applied to predict the oil in water systems and the effects of viscosity and density crude oil on separation of dispersed phase and mean droplet diameter (D4,3) were investigated. Finally, adjustable coefficients in the equations were estimated. The results showed that, by reducing the density of crude oil the settling velocity increases. Furthermore, the decreasing in crude oil viscosity will lead to increase the frequency collision droplets and oil separation.

Keywords

Main Subjects

#### References

[1] امانی آ.، سلیمانی نظر ع.ر.، مدل‌سازی مونت‌‌کارلو در پیش بینی دینامیکی توزیع اندازه قطره‌های تعلیق آب ـ نفت خام، نشریه شیمی و مهندسی شیمی ایران، (4)37:  235 تا 246 (1397).
[2] Salam K., Alade A., Arinkoola A., Opawale A., Improving the Demulsification Process of Heavy Crude Oil Emulsion through Blending with Diluent, Journal of Petroleum Engineering., 2013: (2013).
[3] Manning F.S., Thompson R.E.,”Dehydration of Crude Oil, in Oilfield Processing Volume2: Crude Oil, PennWell”, Tulsa, PennWell Books, 113-143 (1995).
[4] Pak. A., Mohammadi T., Wastewater Treatment of Desalting Units., Desalination, 222(1-3): 249–254 (2008).
[5] Chanamai, R., Coupland, J. N., McClements, D. j., Effect of Temperature on the Ultrasonic Properties of Oil-in-Water Emulsions, Colloids and Surfaces A: Physicochemical and Engineering Aspects., 139(2): 241-250 (1998).
[6] جلایر م.، پیرزاده م.، مکبری ع.، نصرآبادی م.، فرایند نمک‌زدایی نفت خام و اثر آن بر خوردگی بالاسری برج تقطیر  )مطالعه موردی(، نخستین همایش مهندسی فرایند در صنایع نفت، گاز، پتروشیمی و انرژی، تهران، 1 تا 4 (1392).
[7] کشاورز ح.، اسفندیاری ن.، بررسی روش‌های نمک‌زدایی از نفت خام، سومین همایش ملی نفت و گاز و صنایع وابسته، کرمان، 1 تا 7 (1394).
[6] Alopaeus V., Koskinen J., Keskinen K.I., Utilization of Population Balances in Simulation of Liquid-Liquid Systems in Mixed Tanks. Chemical Engineering Communications, 190: 1468-1484 (2003).
[9] سعادت ج.، پاکیزه م.، مروری بر روش‌های تصفیه پساب‌های روغنی با تأکید بر روش‌های غشایی، فرآیند نو، (54)10: 52 تا 57 (1394).
[7] Khajehesamedini A., Sadatshojaie A., Parvasi P., Rahimpour M.R., M. Naserimojarad M., Experimental and Theoretical Study of Crude Oil Pretreatment using Low-Frequency Ultrasonic Waves, Ultrason.Sonochem., 48: 383-395 (2018).
[8] Mitre J.F., Lage P.L., Souza M.A., Silva E., Barca L.F., Moraes A.O., Coutinho R.C., Fonseca E.F., Droplet Breakage and Coalescence Models for the Flow of Water-in-Oil Emulsions through a Valve-Like Element. Chemical Engineering Research and Design, 92: 2493-2508 (2014).
[9] Zhang L., He G., Ye D., Zhan N., Guo, Yongsheng., Fang, Wenjun., Methacrylated Hyperbranched Polyglycerol as a Novel High-efficient Demulsifier for Oil-in-Water Emulsions, Energy Fuels, 30(11): 9939-9946 (2016).
[10] Sterling M.C., Bonner J.S., Page C.A., Fuller C.B., Ernest A.N.S., Autenrieth R.L., Modeling Crude Oil Droplet – Sediment Aggregation in Nearshore Waters, Environmental Science Technology., 38: 4627-4650 (2004).
[11] Attarakih M.M., Bart H.J., Faqir N.M., Numerical Solution of the Spatially Distributed Population Balance Equation Describing the Hydrodynamics of Interacting Liquid-Liquid Dispersion, Chemical Engineering Science., 59: 2567-2585 (2004).
[12] Jeelani S.A.K., Hartland S., Effect of Dispersion Properties on the Separation of Batch Liquid-Liquid Dispersions, Industrial & Engineering Chemistry Research, 37: 547-565 (1998).
[13] Cunha R.E.P., Fortuny M., Dariva C., Santos A.F., Mathematical Modeling of the Destabilization of Crude Oil Emulsions Using Population Balance Equation, Industrial & Engineering Chemistry Research, 47: 7094-7103 (2008).
[14] Nopens I., Biggs C.A., De Clercq B., Govoreanu R., Wilén B.M., Lant P., Vanrolleghem P.A., Modelling the Activated Sludge Flocculation Process Combining Laser Light Diffraction Particle Sizing and Population Balance Modelling (PBM), Water Science and Technology, 45(6): 41–49 (2002).
[16] Nasiri, H. GH., Mosavian, M. T., Kadkhodaee, R., Demulsification of Gas Oil/Water Emulsion via High-Intensity Ultrasonic Standing Wave, Journal of Dispersion Science and Technology, 34(4): 483-489 (2013).