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Solvent Deasphalting

on . Posted in Refinery Engineering

Solvent deasphalting, abbreviated as SDA, is a refining process used to separate heavier components (asphaltenes) from crude oil, vacuum residue, or other heavy oil fractions.  The purpose of SDA is to produce deasphalted oil (DAO), a lighter fraction that can be further processed or used to produce lubricants, while also isolating asphaltenes that can either be used as fuel or disposed of.

Key Points about  Solvent Deasphalting

Mixing with Solvent  -  The heavy oil feed is mixed with a light paraffinic solvent, such as propane, butane, or pentane.  These solvents have a low affinity for asphaltenes, allowing separation based on solubility.
Precipitation of Asphaltenes:  -  The solvent causes asphaltenes to precipitate out of the oil mixture due to their higher molecular weight and polarity, forming a solid or semi-solid phase that can be separated.
Separation  -  The mixture is sent to a separator, where the precipitated asphaltenes are removed from the lighter, deasphalted oil.  This is often done using settling, centrifugation, or filtration.
Solvent Recovery  -  The solvent used in the process is separated from the DAO and asphaltene streams and then recycled back into the system for reuse.

Advantages of Solvent Deasphalting

Improves Feed Quality  -  Produces a deasphalted oil that is lower in sulfur, metals, and heavy components, making it suitable for further refining.
Increases Refinery Flexibility  -  Refineries can use SDA to manage heavy crudes and increase the production of higher-value products.
Environmental Benefits  -  SDA can reduce waste by turning asphaltenes into fuel or other products, rather than requiring disposal.

Applications of SDA

Lubricant Production  -  Deasphalted oil can be used to produce high-quality lubricants.
Fuel Oil and Bitumen  -  Asphaltenes are often used as a source of fuel or as a raw material for bitumen production in paving and roofing.
Upgrading Feedstock  -  DAO is often used as feedstock for further upgrading in Fluid Catalytic Cracking (FCC) or Hydrocracking units.

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