Solvent Dewaxing
Solvent dewaxing is a process used in oil refineries to remove wax from lubricating oil stocks to improve their flow properties, especially at low temperatures. In this process, waxy feedstocks, such as vacuum distillates, are mixed with solvents to separate out waxy components, which can hinder the oil's performance.
Breakdown of the Solvent Dewaxing Process
Mixing with Solvent - The oil stock is mixed with a solvent, commonly a mixture of methyl ethyl ketone (MEK) and toluene. These solvents are effective at dissolving the oil but not the wax, especially at colder temperatures.
Cooling and Crystallization - The oil-solvent mixture is gradually cooled, causing the waxes to crystallize. Cooling is usually done in stages to control crystal size and growth, optimizing wax separation.
Wax Separation - The mixture is then passed through a filtration or centrifugation process. The solid wax crystals are separated out, leaving behind a dewaxed oil.
Solvent Recovery - The solvents used are then separated from the oil, typically through distillation or evaporation, and are recycled back into the process.
Final Product - The result is a dewaxed lubricating oil with improved flow characteristics suitable for use in various temperature sensitive applications.
Tags: Refinery