Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Patent
1998-04-20
2000-06-06
Carr, Deborah D.
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
554202, 208180, C11B 312
Patent
active
060720654
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for refining used oils leading to refined oil products which can be re-used as base oils, fuel oils, or in an oil refinery.
According to the present application, the expression <<used oils>> designates an oil or a mixture of oils in variable proportions originating from various origins in particular from industrial applications.
As this is well known, industrial or engine lubricant oils contain various additives used to provide the required specific characteristics for the contemplated applications. These additives are either organic (known as <<ashless additives>>) or organometallic. Apart from their specific feature (e.g. anti-corrosion, anti-wear, anti-oxidant, dispersant . . . ) they are all characterized by an excellent solubility in base oils (hydrocarbons with boiling points above 350.degree. C.) a thermal stability as high as possible and a volatility as low as possible.
The lubricants which are discarded or used oils contain as impurities such additives either intact or under the form of decomposed by-products, as well as sediments (wear particles from moving parts, airborne particles, carbon . . . ) and hydrocarbons which were not present in the original lubricant and which are undesirable. The latter are essentially gasoline and gas--oil fractions, oxidation products (e.g. organic acids) and pyrolysis products. The presence of these various impurities is rendering particularly difficult the refining of used oils.
In general, industrial used oils as above defined exhibit the typical characteristics given in the following Table 1:
TABLE 1 ______________________________________
Chlorine content (mg/kg)
150-2000
Phosphorus content (mg/kg)
300-1300
Silicon content (mg/kg)
8-80
Colour (ASTM D 1500) >8
Odour (sensorial evaluation)
very strong
Water content (wt %) 0.2-1.2
Sediments (wt %) 0.1-0.5
Viscosity at 40.degree. C. (mm.sup.2 /s)
35-140
Total Acid Number (TAN, mg KOH/g)
0.9-4.5
Saponification Number (SN, mg KOH/g)
4-17
______________________________________
In Table 1 above, the phosphorus and silicon contents were determined by plasma, the chlorine contents either by X-Fluorescence (above 50 mg/kg) or coulometry (below 50 mg/kg), the Total Acid Number through the NFT 60112 French standard, the viscosity at 40.degree. C. through the NFT 60110 standard, the color through the ASTMD 1500 standard; the odour was tested by sensorial evaluation of the operator and the Saponification Number was determined by potentiometry.
In order to separate the various contaminants from used oils and especially to improve their colour and odour, several physical and/or chemical separation methods as well as refining processes have been developed in order to reclaim them and use them as base oils, fuel oils or in an oil refinery.
When a base oil application is contemplated the colour must be very low (at least below 4 according to the ASTM D 1500 standard).
When a combustible application is considered, such as in industrial heating systems, they must be odour free and exhibit a low residual acidity (i.e. TAN below 0.2 mg KOH/g) and a low chlorine content, a potential source of atmospheric pollutants.
Last, when they are to be treated in oil refineries (catalytic cracking or hydrogenation) their phosphorus, silicon and chlorine contents must be very low to avoid catalyst poisoning or destruction (i.e. more specifically a phosphorus content of less than 5 mg/kg, a chlorine content below 35 mg/kg) and a silicon content of less than 5 mg/kg).
Among the known physical separation methods for treating used oils, it can be cited vacuum distillation, solvent precipitation with a solvent such as propane or "deasphalting" and ultra filtration. They all show a significant effectiveness to remove sediments and, to a certain extent demetallize or clarify used oils. However such physical methods do not enable to remove all the impurities in the used oils. Thus, for example, distilled fractions still have a
REFERENCES:
patent: 3625881 (1971-12-01), Chambers
patent: 4097369 (1978-06-01), Ebel et al.
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