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USED LUBE OIL REREFINING - A SUCCESSFUL INVESTMENT
Used lube oil re-refining presentation »
API DEFINITION FOR BASE OILS
Guidelines on Base Oil Quality Assurance and Base Oil Interchange classify base stocks into six base stock groups according to defined physical and chemical characteristics as follows:
Group I
Base stocks containing less than 90 mass percent saturates and/or greater than 0.03 mass percent sulphur and having a viscosity index greater than or equal to 80 and less than 120.
Group II
Base stocks containing greater than or equal to 90 mass percent saturates and less than or equal to 0.03 mass percent sulphur and having a viscosity idnex greater than or equal to 80 and less than 120.
Group III
Base stocks containing greater than or equal to 90 mass percent saturates and less than or equal to 0.03 mass percent sulphur and having a viscosity index of greater than or equal to 120.
Group IV
Base stocks are polyalphaolefins (PAO)
Group V
All base stocks not included in Groups I, II, III, IV or VI.
Group VI
Base stocks are polyinternalolefins (PIO)
| Property | Test Method |
| Saturates Content | ASTM D 2007 |
| Viscosity Index | ASTM D 2270 |
| Sulphur Content | ASTM D 2622, ASTM D 4294, ASTM D 4927, ASTM D 3120 |
STP RE-REFINING PROCESS
STP Re-refining Process removes all the contaminants from the used lube oil and produce high quality base oil either API Group I by chemical finishing or API Group I+ and Group II by Hydrofinishing.
STP Re-refining process does not release harmful or pollutant wastes to be disposed and is therefore environment friend.
Effluents are process water sent to treatment before disposal and off gas from vacuum ejector sets routed to thermal oxidizer to prevent smelling.
- Continuous plant operation
- High flexibility towards feedstock quality and composition
- High process yield. The lube oil recovery is more than 95% of the lubricant fraction present in the used oil.
- High separation selectivity, removal of contaminants and production of high quality base oils
- Low energy and low utility consumption
- High on-stream efficiency without corrosion, fouling, coking
- Environment safeguarding operation and no use of acid and clays
- Management of all odorous compounds to eliminate malodorous and toxic emissions
- Capital investment and operating cost highly competitive
UNIT OPERATIONS
1. DEHYDRATION
Used oil is preheated to remove water, gasoline, VOC, light contaminants (solvents, glycols, lighter organic). Water is sent to treatment and lights (gasoline) are used as substitution fuel.
2. GASOIL REMOVAL
Dehydrated oil is stripped under vacuum for light gasoil removal and flash point adjustment of lube oil.
3. VACUUM DISTILLATION
Oil from gasoil stripper is sent to vacuum distillation to recover vacuum distillate oil fraction from heavier contaminants.
Vacuum distillation is carried out under high vacuum conditions, high temperature and by thin film evaporator.
Thin film evaporator achieves high selectivity and oil purification from metals, heavy polymers, carbon, dust.
FOCUS ON THIN FILM EVAPORATOR (pdf) »
4. FINISHING AND FINAL FRACTIONATION
Vacuum distillate is further finished to improve product quality.
Finishing is done by Chemical Reactor to produce Base oil API Group I or by Hydrofinishing
to produce Base oil API Group I+ and API Group II.
Hydrofinishing provides deep removal of contaminants such as chlorinated, sulfurous, and oxygenated organic compounds and polyaromatic hydrocarbons.
Mild Hydrofinishing is used to produce Base oil API Group I+.
Severe Hydrofinishing is required to produce Base oils API Group II.
Finished oil is then fractionated to produce light base oil and heavy base oil.
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