Solvent deasphalting (SDA) is a critical technology in heavy oil refining for separating deasphalted oil (DAO) from residues. However, conventional systems face persistent challenges, including low mass transfer efficiency, operational instability due to frequent clogging, and high costs associated with solvent recovery. This study addresses these limitations through the development of advanced structured packings and distributors, aiming to enhance separation performance, operational flexibility, and economic viability.
Traditional extraction towers equipped with commercial corrugated packings exhibit a surface area of 233.156 m²/m³ but suffer from low flooding capacity, limiting throughput. In contrast, commercial grid packings, with a surface area of approximately 20 m²/m³, fail to achieve satisfactory separation efficiency. Furthermore, branch-pipe distributors commonly used in such systems are prone to clogging when processing low-quality residues, leading to uneven fluid distribution and reduced process reliability.
To overcome these issues, this study introduces a novel structured packing design grounded in mass transfer theory and fluid dynamics principles. The extraction packing was engineered with a specific edge length of 24.4×10³ m/m³—significantly higher than the 6.7×10³ m/m³ of commercial corrugated designs—to enhance droplet breakup and surface renewal. The increased edge length promotes turbulence within the liquid phase, improving interfacial contact and mass transfer coefficients. Hydrophobic materials were incorporated into the packing structure to suppress droplet coalescence, ensuring stable dispersion. Experimental evaluations demonstrated that the optimized packing achieved a 24% higher flooding capacity compared to commercial corrugated packings while maintaining a dispersed-phase holdup of 4.72%, closely matching the 5.75% observed in conventional systems.
Complementing the packing design, a CFD-optimized square-loop distributor was developed to address clogging and distribution inefficiencies. Computational fluid dynamics simulations revealed that the distributor achieved high radial uniformity in fluid dispersion, effectively eliminating localized sedimentation. The square-loop configuration minimizes cross-sectional area occupation, allowing higher throughput while reducing emulsification risks caused by high liquid velocities. By gently introducing supercritical fluid and DAO into the solvent recovery tower, this design mitigates phase mixing and accelerates droplet settling, thereby lowering the required height of coalescing packings.
For phase separation in the solvent recovery tower, coalescing packings with DAO-affinitive materials were developed. These materials selectively capture DAO droplets, promoting coalescence and increasing the average droplet size from 4.86 mm to 7.36 mm. This improvement enhances separation efficiency and reduces solvent carryover, critical for minimizing downstream processing costs.
The efficacy of these innovations was adopted in a full-scale design at the 2-million-ton SDA unit. The optimized extraction tower, with a 5 m diameter and 4.5 m extraction height, achieved an 80.23% DAO yield at a solvent ratio of 3, outperforming conventional technologies that typically yield 65%. The enhanced flooding capacity enabled a 15% increase in throughput. Operational data further indicated that the tower maintained stable performance across varying solvent ratios (2.43–3) and feed rates (120–220 kt/a), underscoring its operational flexibility.
These advancements highlight the transformative potential of high-efficiency internals in solvent deasphalting. By integrating optimized packings and distributors, refineries can achieve higher throughput, reduced operational costs, and improved product quality. Future work will focus on scaling production techniques and exploring advanced materials to further enhance durability and separation performance.