Upgrading of Heavy Crudes and Residue for Liquid fuels production

Abstract

Trends have predicted that peak oil production, will be reached around 2020-2030, where the production of oil starts to decline after that, there will be less and less oil to refine, the depletion of light oil and the severe shortage of light products is what compelled us to search for solutions to provide the necessities, observe that the crude that feeds the refineries have become more heavy, so it was necessary to develop oil refining processes to meet the production requirements in quantity and quality. This study aims to search for solutions to the problem of heavy sudanese crude oil and residues to produce light products to fill the shortage, and El Obeid refinery was taken as a case. A detailed simulation of an atmospheric distillation column was performed using Aspen Hysys v.10 software. The model was based on data from the actual plant located in El Obeid refinery in North of Kordofan. Crude oils were described using True Boiling Point (TBP) assays and a Peng-Robinson package was used to predict thermodynamic properties. Three different types of crude oils (Nile Blend, Rawat, Thargath), and 7 blends with different proportions were selected from the previous crude oils. The simulation results agree well with those of the industrial plant in the case of the Nile blend and the validity of the model is confirmed. The conversion ratio to high-value light products in the atmospheric distillation tower of the Nile blend ware 31%vol, Rawat were 39.7%vol, Thargath were 24.22%vol, Mix 1 were 30.51%vol, Mix 2 were 26.62%vol, Mix3were 31.23%vol, Mix 4 were 28.96%vol, Mix 5 were 30.47%vol, Mix 6 were 27.97%vol and Mix 7 were 27.81%vol. It was proposed to add a new unit (atmospheric distillation tower) identical to the first distillation tower to increase the inputs to the second proposal (vacuum distillation tower) to convert the residues of towers into light products, four streams were selected from to feed their residues to the vacuum distillation tower, and the residues were converted to high-value light products. The selected streams were (Nile Blend, mix 1, mix 3 and mix 7) and the percentage of convertion into light products were (52.57%, 57.48% ,62.57% and 66.94%) by volume respectively. These results clearly indicate that blending the Sudanese heavy crudes improves their properties and gives better desired products than Nile blend as in Mix 1, Mix 3 and Mix 7.