Mineral oils: processes and products – Refining – Purifying used oil
Patent
1990-02-20
1992-08-25
Myers, Helane
Mineral oils: processes and products
Refining
Purifying used oil
208179, 208181, 208186, 208187, 2082625, 208180, C10G 2920, C10G 2922
Patent
active
051416280
DESCRIPTION:
BRIEF SUMMARY
The invention is directed to a method of cleaning and reclaiming used oils, especially used engine and lube oils, by filtering, heat treatment and stripping of the light ends comprising solvents and water.
Used oils are especially mineral oils. The service value of motor oils and especially lube oils is considerably affected by oxidation products, contaminants and other impurities which accumulate during use. Such products can no longer fully satisfy the requirements and must be exchanged. They are known as used oils and are collected and reprocessed for reasons of environmental protection, conservation of resources and also under economic aspects. Used oils are predominantly composed of a base stock on the basis of mineral oil or synthetic oil, but they comprise considerable amounts of foreign materials such as water, solvents, motor fuel, asphalt-like materials, acids, resins, ashes and additives such as antioxidants, anticorrosives, wetting agents, dispersants, antifoam agents and viscosity index improvers. The additives may contain halogen, sulphur and nitrogen compounds as well as numerous other and partly toxic components.
Used oils are initially cleaned mechanically by separating undissolved contaminants and impurities by means of sedimentation, filtering or centrifuging. The separation can be considerably accelerated when the used oil is heated to a temperature of 50.degree. to 100.degree. C.
Conventional reclaiming of used oils is effected in a multi-stage process as described in Ullmanns Encyklopadie der technischen Chemie, 4th edition, vol. 20, p. 498. Following the rough removal of water and solid impurities, light ends and residual water are removed by atmospheric distillation at a temperature of about 250.degree. C., whereafter oxidation products and additives are removed by sulphuric acid refining with subsequent calcium neutralization, and the refinery residue is removed by decanting or filtering, respectively. The breakdown into one to two light-viscosity or medium-viscosity distillate and residue fractions occurs by vacuum distillation at a pressure of 80 to 100 mbar, and finally the fractions are fined and stabilized by clay treatment.
According to the PROP process of Phillips Petroleum Co. as described in Hydrocarbon Processing, September 1979, pp. 148 et seq., used oil after pretreatment with an aqueous solution of diammonium phosphate is subjected to refining hydrogenation over nickel-molybdenum catalysts. Although it is said that in this process polychlorinated biphenyls are also decomposed at least partially, chlorinated solvents and wash solvents, metal machining oils and other machining oils having no clearly identified composition, as well as insulating and transformer oils should not be contained in the feedstock for this reclaiming process. Suitable feedstock for this process therefore are substantially used motor oils.
According to the KTI process of Kinetics Technology International, the used oil is freed by sedimentation from water and contaminants and is then freed by atmospheric distillation from residual water and light ends. Thereupon the gas oil fraction is removed in a separate step. In the subsequent vacuum distillation, the lube oil components are fractionated, condensed and any dirt, additives and part of the oxidation products are extracted as bottoms. The distillates are hydrofined and stripped. Since acid refining is not provided also in this process, additives or foreign components must be either removable by distillation or capable of conversion by hydrogenation. Ingredients must not affect the activity of the hydrogenation catalyst so that cutting oils, for instance, which contain halogenated hydrocarbons likewise cannot be processed by this method, see Ullmanns Encyklopaie der technischen Chemie, 4the edition, vol. 20, p. 500.
In the Recyclon processes, the oxidation products and additives are likewise not removed by means of sulphuric acid but are removed by treatment with dispersed sodium, whereby they either polymerize or are transformed to sodium salts ha
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Martin Erich-Klaus
Onabajo Adekunle
Myers Helane
RWE-Entsorgung Aktiengesellschaft
Whaley Thomas H.
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