Application: Bechtel’s Dewaxing process is used to remove waxy components from lubrication base-oil streams to simultaneously meet desired low-temperature properties for dewaxed oils and produce slack wax as a byproduct.
Description: Waxy feedstock (raffinate, distillate or deasphalted oil) is mixed with a binary-solvent system and chilled in a very closely controlled manner in scraped-surface double-pipe exchangers (1) and refrigerated chillers (2) to form a wax/oil/solvent slurry.
The slurry is filtered through the primary filter stage (3) and dewaxed oil mixture is routed to the dewaxed oil recovery section (5) to separate solvent from oil. Prior to solvent recovery, the primary filtrate is used to cool the feed/solvent mixture (1). Wax from the primary stage is slurried with cold solvent and filtered again in the repulp filter (4) to reduce the oil content to approximately 10%.
The repulp filtrate is reused as dilution solvent in the feed chilling train. The wax mixture is routed to a solvent-recovery section (6) to remove solvent from the product streams (hard wax and soft wax). The recovered solvent is collected, dried (7) and recycled back to the chilling and filtration sections.
Licensor: Bechtel Corp.