Document Type : Full article

Authors

1 Department of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114, Iran

2 Iran University of Science and Technology

Abstract

In this work, the demulsification of water-in-crude oil emulsions by dielectrophoresis via applying a non-uniform electric field in a lab-scale cylindrical cell was studied. The stability of emulsions was assessed through monitoring the size distribution of water droplets at 0, 3, 6, and 24 hours after the preparation of emulsion. The effect of operating parameters including the temperature, demulsifier concentration, water salinity, and time on the demulsification of water was investigated. Sodium dodecyl sulfate and sodium chloride were used as demulsifier and salt respectively. The experiments were designed by the response surface methodology (RSM) based on the central composite design (CCD). The operating parameters including the voltage, temperature, demulsifier concentration, salinity of water, and separation time were optimized. The contours and 3-D response surfaces of the water separation were acquired. A quadratic polynomial model, which was statistically highly significant (R2=0.9950, n=32), was provided by the RSM to predict the amount of the separated water. Comparison among the experimental and RSM-optimized values indicates a good agreement. The optimum amount of the water separation was obtained at the voltage of 15 kV, temperature of 60 °C, demulsifier concentration of 123 ppm, salinity of water of 12260 ppm, and separation time of 12.4 minutes. Under such conditions, the separation of water reached 98 %. The results obviously show that the electric field can be used as an appropriate means for the breakage of W/O emulsions.

Keywords

[1]      Hajivand, P. and Vaziri, A., “Optimization of demulsifier formulation for separation of water from crude oil emulsion”, Brazilian J. Chem. Eng., 32, 107 (2015).
[2]      Kokal, S., Crude oil emulsions, Petroleum engineering handbook, (2006).
[3]      Smith, H. V. and Arnold, K., Crude oil emulsions (1987 PEH Chapter 19), Petroleum engineering handbook, (1987).
[4]      Rodionova, G., Kelesoglu, S. and Sjöblom, J., “AC field induced destabilization of water-in-oil emulsions based on North Sea acidic crude oil”, Colloids Surfaces A Physicochem Eng. Asp., 448, 60 (2014).
[5]      Kilpatrick, P. and Spiecker, P., Asphaltene emulsions, Marcel Dekker, New York, (2001).
[6]      Ashtari, M., Ashra, S. N. and Bayat, M., “Asphaltene removal from crude oil by means of ceramic membranes”, J. Pet. Sci. Eng., 82-83, 44 (2012).
[7]      Li, Q., Chen, J., Meng, L., Liang, M., Pan, Z. and Wang, K., “Investigation of water separation from water-in-oil emulsion using high frequency pulsed AC electric field by new equipment”, J. Dispers. Sci. Technol., 36, 918 (2015).
[8]      Verruto, V. J., Le, R. K. and Kilpatrick, P. K., “Adsorption and molecular rearrangement of amphoteric species at oil-water interfaces”, J. Phys. Chem. B, 113, 13788 (2009).
[9]      Mohammadi, M., Shahhosseini, S. and Bayat, M., “Direct numerical simulation of water droplet coalescence in the oil”, Int. J. Heat. Fluid Flow, 36, 58 (2012).
[10]  Wu, J., Xu, Y., Dabros, T. and Hamza, H., "Effect of demulsifier properties on destabilization of water-in-oil emulsion”, Energy and Fuels, 17, 1554 (2003).
[11]  Yi, M., Huang, J. and Wang, L., “Research on crude oil demulsification using the combined method of ultrasound and chemical demulsifier”, J. Chem.,2017, (2017).
[12]  Venault, A., Jumao-as-Leyba, A. J., Chou, F. C., Bouyer, D., Lin, I. J., Wei, T. C. and Chang, Y., "Design of near-superhydrophobic/superoleophilic PVDF and PP membranes for the gravity-driven breaking of water-in-oil emulsions”, J. Taiwan Inst. Chem. Eng., 0, 1 (2016).
[13]  Zhang, L., He, L., Ghadiri, M. and Hassanpour, A., “Effect of surfactants on the deformation and break-up of an aqueous drop in oils under high electric field strengths”, J. Pet. Sci. Eng., 125, 38 (2015).
[14]  Muto, A., Matsumoto, T. and Tokumoto, H., “Continuous flow demulsification of a water-in-toluene emulsion by an alternating electric field”, Sep. Purif. Technol.,156, 175 (2015).
[15]  Yang, D., Xu, M., He, L., Luo, X., Lü, Y., Yan, H. and Tian, C., “The influence and optimisation of electrical parameters for enhanced coalescence under pulsed DC electric field in a cylindrical electrostatic coalescer”, Chem. Eng. Sci., 138, 71 (2015).
[16]  Kar, T. and Hascakir, B., "The role of resins, asphaltenes, and water in water-oil emulsion breaking with microwave heating”, Energy and Fuels, 29, 3684 (2015).
[17]  Eow, J. S., Ghadiri, M., Sharif, A. O. and Williams, T. J., “Electrostatic enhancement of coalescence of water droplets in oil: A review of the current understanding”, Chem. Eng. J., 84, 173 (2001).
[18]  Eow, J. S. and Ghadiri, M., “Electrostatic enhancement of coalescence of water droplets in oil: A review of the technology”, Chem. Eng. J., 85, 357 (2002).
[19]  Sun, D., Duan, X., Li, W. and Zhou, D., “Demulsification of water-in-oil emulsion by using porous glass membrane”, J. Memb. Sci., 146, 65 (1998).
[20]  Pethig, R., “Dielectrophoresis: Status of the theory, technology, and applications”, Biomicrofluidics, 4, 022811 (2010).
[21]  Monfared, M. A., Kasiri, N. and Mohammadi, T., “A CFD model for prediction of critical electric potential preventing membrane fouling in oily waste water treatment”, J. Memb. Sci., 539, 320 (2017).
[22]  Pohl, H. A., The motion and precipitation of suspensoids in divergent electric fields”, J. Appl. Phys., 22, 869 (1951).
[23]  Molla, S. H. and Bhattacharjee, S., “Prevention of colloidal membrane fouling employing dielectrophoretic forces on a parallel electrode array”, J. Memb. Sci., 255, 187 (2005).
[24]  Du, F., Hawari, A. and Baune, M., “Dielectrophoretically intensified cross-flow membrane filtration”, J. Memb. Sci., 336, 71 (2009).
[25]  Alinezhad, K., Hosseini, M., Movagarnejad, K. and Salehi, M., “Experimental and modeling approach to study separation of water in crude oil emulsion under non-uniform electrical field”, Korean J. Chem. Eng., 27, 198 (2010).
[26]  Du, F., Ciaciuch, P., Bohlen, S., Wang, Y., Baune, M. and Thöming, J., “Intensification of cross- flow membrane filtration using dielectrophoresis with a novel electrode configuration”, J. Memb. Sci.,448, 256 (2013).
[27]  Xia, L., Lu, S. and Cao, G., “Stability and demulsification of emulsions stabilized by asphaltenes or resins”, J. Colloid Interface Sci.,271, 504 (2004).
[28]  Daniel-David, D., Le Follotec, A., Pezron, I., Dalmazzone, C., Noik, C., Barre, L. and Komunjer, L., “Destabilisation of water-in-crude oil emulsions by silicone copolymer demulsifiers”, Oil Gas Sci. Technol., 63, 165 (2008).
[29]  Chong, J. Y., Machado, M. B., Bhattacharya, S., Ng, S. and Kresta, S. M., “Reduce overdosing effects in chemical demulsifier applications by increasing mixing energy and decreasing injection concentration”, Energy and Fuels, 30, 5183 (2016).
[30]  Xu, Y., Wu, J., Dabros, T. and Hamza, H., “Optimizing the polyethylene oxide and polypropylene oxide contents in diethylenetriamine-based surfactants for destabilization of a water-in-oil emulsion”, Energy and Fuels, 19, 916 (2005).
[31]  Dimitrov, A. N., Yordanov, D. and Petkov, P. S., “Study on the effect of demulsifers on crude oil and petroleum products”, Int. J. Environ. Res., 6, 435 (2012).