Re-Refining Process
The SOR process replicates the original processes that crude oil distillates undergo in a typical virgin base oil refinery, but with special emphasis on purifying the used oil of:
- degradation products of lube oil additives,
- condensed transport fuels (naphtha and diesel) from cold start engine usage,
- complex polycyclic hydrocarbons formed in combustion processes such as polycyclic aromatics/polyaromatic hydrocarbons, and dioxins/furans as well as any minor quality control breaches such as chlorinated solvents (eg TCEs).
The SOR process is one of multistage vacuum separations to ensure maximum recovery of distillates of all standard boiling point ranges into discrete products that maximise product values.
The principle of multiple unit operations has been found to give optimum controllability of each stage to ensure overall process performance is optimised with minimum contamination between stages.
There is also a presentation available about the SOR re-refining process:
- Download powerpoint presentation (Powerpoint viewer required, 650k)
- Adobe Acrobat PDF file (Adobe Acrobat required, 533k)
- Online as a web page (Opens in new window)
The SOR used oil re-refining process is made up of four main stages as follows:
| 1/ | Used Oil Stabilisation -
Used Oil is chemically active due to the presence of water (typically
up to 10%) and the degradation products of the various chemical additives
in lube oils leading to a risk of process corrosion and reactivity
of the various products. . . |
| 2/ |
Multi-stage Flash Distillation -The stabilised
used oil passes through a number of evaporation units involving
both simple flash evaporation and film evaporation to separate the
distillate fractions from the residue. |
| 3/ | Fractionation - Continuous
multistage distillation is a process of whereby the various fractions
of fuel and lube distillates are separated through continuous vaporisation,
stripping and rectification. . . |
| From this part
of the SOR re-refining process, five well-defined product streams
are produced as fuel oils or as distillates for further processing
in the solvent plant. . . |
|
| 4/ | Solvent Treating - The unique
SOR process for achieving virgin base oil quality uses a combination
of solvent extraction and recovery techniques to remove contaminants
that could adversely affect the safety and performance of the product.
The main solvent used is NMP a commonly used solvent in the pharmaceutical
and petrochemical industries. . . |
Particular care is taken to enable maximum phase separation from the solvent and distillate, which under some conditions have very similar densities making economic plant operation and good separation a challenging design task. The solvent recovery and base oil stripping stages are further areas where SOR has through its operating experience determined optimal operations.
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