Feasibility and economic analysis of diesel oil extraction from oiled-sand by supercritical CO₂ process

To analyze the feasibility and economy of diesel oil extraction by supercritical CO₂ from oiled-sand, the relationship curve between the solubility in supercritical CO₂ and the extraction efficiency was obtained according to the corresponding references and experimental data. Results show that when the solubility is more than 25 g/(100 g), the extraction efficiency can reach 98%. Aspen software was used for simulating the extraction efficiency of the main compounds of C₁₀~C₂₀ in diesel oil, and the operation parameters such as pressure, extraction time and CO₂ flow rate were optimized. It is shown that at the condition of 35℃, 20 MPa, extraction time of 180 min, CO₂ flow rate of 60 kg/h and methanol to CO₂ ratio of 0.3, the extraction efficiency of the C₁₀~C₂₀ compounds can reach 95%. The technical and economic analyses of a 20 t/d supercritical CO₂ extraction system show that the construction investment is 15 million yuan, and 24 000 yuan can be earned per day when the oiled-sand with an oil mass fraction of 21% is treated by this system. So the initial construction investment can be recovered in two years. The supercritical CO₂ extraction process can not only solve the pollution problem of the existing oiled-sand, but also recover the diesel oil effectively, thus alleviating the increasingly tense supply-demand relationship of oil and fuel gas.