MEK De-waxing of Sudanese crude oil (Rawat) to enhance their physical and molecular characterization
Mahjoub A Afandi, Elmugdad AA, M Zaky, Fathi S Soliman
Waxy crude oil creates difficulties during transportation and refining process. This study investigated the feasibility of Methyl Ethyl Ketone (MEK) as selective solvent to de-wax a Sudanese heavy crude oil (Rawat area) with wax content 26.3 wt% and pour point 54°C and determine the possible optimum conditions. Experiments were conducted on four solvent to feed ratios (10: 1, 8: 1, 6: 1 and 4: 1) at de-waxing temperature -10 °C, mixing temperature 40°C and crystallization time 24 hrs. The crystallized wax which forms in the mixture was then vacuum filtered, dried, and weighed. The results indicated that MEK de-waxing performance improved at higher mixing temperatures. This could be explained by the disruption of dispersion forces which exist between the molecules in the crude oil, allowing new intermolecular bonds to form between MEK and oil molecules in greater preference than with the wax molecules. It was also discovered that the use of a higher solvent to oil ratio resulted in a greater wax yield that is attributed to a greater oil solubility, In contrast, it was found that a lower cooling temperature resulted in a greater extraction of wax from the mixture. Finally, the greatest oil yield (19.75 wt%) was achieved at a solvent to oil ratio of 8:01, a mixing temperature of 40°C and a de-waxing temperature of -10°C with pour point - 4.5°C.