Solvent extraction and deasphalting processes - or solvent deasphalting (SDA) as it is commonly known—use hydrocarbons such as propane, butanes, pentanes, or a mixture of these to extract light, paraffinic components from heavy residue streams. Regardless of the level of impurities in the feedstock, these processes effectively produce deasphalted (DAO) or demetallized oil (terms that are used interchangeably). DAO product quality and yield are dependent upon the solvent that is selected for the process; i.e., the quality (metals, sulfur, nitrogen and Conradson carbon levels) of the products—which can be used as lubricating oil base stock or cracker feedstock—decreases with increasing yield and with the use of heavier solvents. Asphalt or pitch from the solvent deasphalter is in the form of a highly-viscous liquid. Previously, this low-value stream was commonly used as a blending component for residual fuel oils. More recently, the conversion of liquid pitch into solid form has been achieved to improve potential end uses of heavy byproducts.
Given the upcoming implementation of the IMO 0.5%-sulfur bunker specification in Jan. 2020, there has been significant focus by global refineries to invest in new technologies that minimize bottoms output, which were typically blended into the bunker pool. SDA technology can be applied in a number of areas in the refinery. Due to its versatility, relatively low capital and operating costs, and low energy requirements, solvent deasphalting can also be integrated in a number of flexible configurations with a range of refinery processing units that will treat the high-quality DAO, intermediate-quality resin, or low-quality pitch: coker, visbreaker, gasifier, resid FCC, resid hydrocracker, etc. Ultimately, refinery liquid yields are improved and production of low-value pitch is significantly reduced or eliminated. Integration opportunities also offer benefits in terms of heat and power consumption and can enhance control of product quality to meet the unique product slate specifications for a particular refiner.
There is also increased interest in applying SDA units upstream to upgrade heavy oil, particularly in Canada. Upgrading heavy oil with solvent deasphalting makes it pipeline and refinery ready while decreasing the use of diluents. Overall, as the worldwide supply of heavy and extra-heavy crude oil increases resulting in an increased quantity of heavy asphaltenes passing through the refinery, plant operators can utilize solvent deasphalting technology as a flexible and robust tool to maintain and/or increase liquid yields and optimize plant economics while processing these discounted heavier feeds.
Additionally, the solvent deasphalting section features the latest trends and technology offerings, including:
- Updated look at the global solvent deasphalting unit including the integration of solvent deasphalting with other bottom-of-the-barrel upgrading units (e.g., visbreaking) in light of the upcoming IMO bunker fuel sulfur mandate;
- SDA-RT process from Amec Foster Wheeler and Honeywell UOP and the integration benefits of this process with delayed coking;
- Update on the licensing of the UOP/Amec Foster Wheeler Solvent Deasphalting technology;
- Case study detailing combinations of H-Oil and Solvahl processes from Axens;
- Residue Solvent Refining Solvent Deasphalting and the LC-MAX processes offered by Chevron Lummus Global;
- Integrated visbreaking and SDA configuration offered by KBR and Shell Global Solutions;
- TWISTED TUBE heat exchanger provided by Koch Heat Transfer Co. and utilized in KBR's ROSE process;
- Update on the licensing, construction, and startup of units utilizing ROSE technology;
- Well Resources SELEX-Asp implemented upstream from hydroprocessing units;
- Update on the commissioned SELEX-Asp units; and
- A discussion of the latest patent applications and research papers regarding solvent deasphalting technology including processes used for upstream upgrading; general processes for downstream operations; deasphalting solvents; hardware; integration of deasphalting with hydroprocessing, thermal/catalytic cracking, and steam pyrolysis; deasphalting processes that yield specialty products; and more.