المجلة العلمية اهرام مجلة مستقلة تحت إشراف هاني سلام
Dr. Hassan ELnagar Hassan Ibrahim
Ph.D. in Material Science
The process for extracting crude oils from the oil fields is costly, complex, and presents various difficulties, which depend on the conditions of each field, climate, and oil composition, among others. The paraffin crystals grow as the temperature decreases, creating a crystalline net, which begins to trap the molecules of liquid hydrocarbon until the oil cannot flow. Paraffin deposition is responsible for the reduction in production, in terms of the facility maintenance and removal of deposits already formed, increasing the cost of producing and transporting oil products and mainly, causing some handling problems in regions where the service temperatures are or become seasonally very low
Therefore, during the production, storing, and transportation of paraffin-based crude oil and its products, it is important to maintain the oil at a temperature above its natural pour point. Thus, chemical products are known as flow improvers, crystal modifiers, and pour point reducers need to be used to reduce the apparent viscosity, the flow limit, and the pour point of oils. Paraffin wax deposition from crude oil at low temperature is one of the serious and long-standing problems in the petroleum industry. At low temperatures, the crystals of wax easily form impermeable cakes, which can block filters and eventually lead to engine failure. Many methods have been attempted for the prevention of the crystals mating together. Since adding chemical additives (such as pour point depressants (PPDs), cold flow improvers, paraffin inhibitors, or wax crystal modifiers) is the most convenient and economic ways to ease the flow of ail, it is widely used in the industry
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It has been found that with the addition of the additives, the shape of the wax crystal changes. Many postulated mechanisms have been put forward to explain this phenomenon and to illustrate the PPD product design. Among the mechanism theories, adsorption, co-crystallization, nucleation, and improved wax solubility are widely accepted by researchers
Paraffin crystal in rigid network adhering to pipe
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Modified crystal unable to form network or adhere to each other on pipe surface
At present, the majority of the pour point depressants are macromolecule polymers, such as ethylene-vinyl acetate copolymer (EVA). Although EVA is widely applied as the crude oil flowing modifier agent, it does not well perform for crude oil. To improve the effect of pour point depressant, the polar groups and the branched chains should be introduced into the macromolecule of EVA
Ethylene-vinyl acetate copolymer (EVA) and its derivatives
In addition, used innovative solvent (PONA) that is obtained from the process of hydrotreating and separation of straight-run naphtha to dissolve polymers as pour point depressant of crude oil. This innovative included study conducted on crude oil. When we used a concentration of 2500 ppm of polymer the pour point of crude oil has decreased from +42 to – 6 °C as a result of the innovative solvent (PONA) in the case of crude oil and this represents a new achievement
References
Alnaimat, F., & Ziauddin, M. (2020). Wax deposition and prediction in petroleum pipelines. Journal of Petroleum Science and Engineering, 184, 106385. doi:10.1016/j.petrol.2019.106385
Burger, E., Perkins, T., & Striegler, J. (1981). Studies of wax deposition in the trans Alaska pipeline. Journal of Petroleum Technology, 33(06), 1075-1086. doi:10.2118/8788-pa
Chen, W., Zhao, Z., & Yin, C. (2010). The interaction of waxes with pour point depressants☆. Fuel, 89(5), 1127-1132. doi:10.1016/j.fuel.2009.12.005
Chen, W., Zhao, Z., & Yin, C. (2010). The interaction of waxes with pour point depressants☆. Fuel, 89(5), 1127-1132. doi:10.1016/j.fuel.2009.12.005
Chevallier, V., Petitjean, D., Bouroukba, M., & Dirand, M. (1999). Mixtures of numerous different N-alkaNes: 2. Studies by X-ray diffraction and differential thermal analyses with increasing temperature. Polymer, 40(8), 2129-2137. doi:10.1016/s0032-3861(98)00409-1
Creek, J., Lund, H. J., Brill, J. P., & Volk, M. (1999). Wax deposition in single phase flow. Fluid Phase Equilibria, 158-160, 801-811. doi:10.1016/s0378-3812(99)00106-5
Deka, B., Sharma, R., Mandal, A., & Mahto, V. (2018). Synthesis and evaluation of oleic acid based polymeric additive as pour point depressant to improve flow properties of Indian waxy crude oil. Journal of Petroleum Science and Engineering, 170, 105-111. doi:10.1016/j.petrol.2018.06.053
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