(185d) The Solvent/DAO Separation for the Maximum Solvent Recovery in a SDA Process

Because of conventional oil being-exhausted and its increasing price, the technologies to use unconventional oil and low value crude residues, which have not been fully exploited, are receiving more and more interest. Solvent deasphalting (SDA) is a technology removing asphaltene rich pitch and producing the higher value deasphalted oil from low value crude residues, using paraffinic solvents (C3-C6). The SDA process is promising because it has advantages of the low installation cost and the flexibility to control the quality of pitch and DAO. DAO, produced by the SDA process, is used as a raw material of the base oil. The remaining residue is used as a road packing material or as a solid fuel, and also it can produce heat and hydrogen through gasification. In the SDA process, a great amount of expensive solvent is used. Thus, the solvent should be recovered as much as possible for reuse, causing high energy consumption in the solvent recovery process. In this study, the characteristics in the separation of solvent and DAO were investigated to develop an efficient process maximizing the solvent recovery with low energy. In the conventional SDA process, huge amount of thermal energy is supplied until the solvent is almost completely vaporized. By contrast, the required energy can be reduced into half or less by separating DAO and solvent in a supercritical condition. In specific supercritical conditions, the solubility of DAO in solvent significantly decreases, resulting improved separation performance. Prior to experiments of separation of DAO and solvent, the condition to make DAO and solvent well-mixed was tested. For the mixture of DAO and solvent, the various conditions including supercritical region were investigated to find the optimal condition of separation by changing temperature, pressure, and a type of solvent. For the analysis of experimental data, a gas chromatography system was used to identify DAO components and to estimate DAO purity and solvent recovery. Furthermore, Aspen Plus simulation was used to confirm the experimental data and to optimize the solvent recovery in the SDA process.