Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M175/00—Working-up used lubricants to recover useful products ; Cleaning
  • C10M175/0016—Working-up used lubricants to recover useful products ; Cleaning with the use of chemical agents

Definitions

• This invention relates to re-refining of waste lubricating oil.
• Waste lubricating oil includes such material as used crankcase lubricating oil from internal combustion engines of motor vehicles. Such waste oil is often collected and is subjected to re-refining processes to remove contaminants and spent additives from the oil in order to produce a base oil from which new lubricants are manufactured. Prior methods of re-refining typically involved the following steps:
• GB-A-2 022 131 discloses a process for regenerating spent lubricating oils, wherein the spent lubricating oil or its crude raffinate is treated with 0.5 to 10 % by weight of a mixture of 20 to 70 parts by weight of potassium hydroxide and 80 to 30 parts by weight of sodium hydroxide at 200-500°C and worked up by one or more of the stages of acidification, distillation, hydrogenation and filtration with fuller's earth.
• increasing amounts of additives used in lubricating oil formulations have made the aforementioned processes increasingly difficult and expensive to operate.
• New methods have evolved that are aimed at avoiding the production of acid sludge and also the avoidance of the use of activated earth. For example, hydro-treatment is used to avoid treatment with activated earth.
• this invention provides a method for reducing acidity of distillates and for reducing the formation of fouling compounds during distillation by treating water-containing waste lubricating oil containing at least 1% by weight water and dibasic metal additives, said method comprising:
• Suitable basic compounds for use in the method of this invention includes basic compounds such as sodium hydroxide.
• basic compounds such as sodium hydroxide.
• the added compound will not prevent the production of acidity in the distillate or reduce plant fouling.
• the basic compound is added to the waste lubricating oil before distillation and while the oil still has some water content, it is possible to prevent the production of acidity in the vapour space and distillates during subsequent distillation.
• the alkalinity of the reagent used to treat the waste oil is not the important factor in the process but rather, the reagent used must be able to provide an alkali metal to substitute for dibasic metals such as calcium that are present in certain lubricating oil additives.
• Waste lubricating oil that has not been subjected to a heat treatment or a drying process will contain some water. Typically the water content will be at least five percent by weight. It is preferable that the method of this invention be carried out that while the waste lubricating oil subjected to the treatment contains at least one percent by weight of water.
• the alkali metal component of the reagent to be used in the method of this invention may include sodium, potassium, and lithium.
• the hydroxide, or a salt of any acid weaker than sulphonic such as carbonate, borate, and sulphide, may be used.
• the pre-treatment process of this invention is most advantageously carried out if the alkali metal reagent is added to the waste lubricating oil in sufficient quantities such that the alkali metal is present in an amount between 70-200% of the stoichiometric equivalent of the total amount of calcium, magnesium, and zinc present in the waste lubricating oil.
• the latter metals are the most common di-basic metals found in waste lubricating oil but there may be others such as barium.
• the stoichiometric range employed will be 80-150% of the total calcium, magnesium, and zinc. Most preferably, the aforementioned stoichiometric relationship is maintained within the range 95-105%.
• the amount of time it takes to dry waste lubricating oil that is subjected to heat varies depending upon the conditions employed. For example, when such oil is heated at approximately 100°C in laboratory conditions, it will usually take at least ten minutes to dry the oil. Under plant conditions, oil may undergo "flash drying” when plant feed is injected into dried oil maintained at 150°C. It is important that the pre-treatment process of this invention be carried out before the oil is dried in order that the reaction in the pre-treatment may proceed.
• the chemical reaction that takes place in the pre-treatment process of this invention is time and temperature dependant. Therefore, the pre-treatment process of this invention may be more quickly carried out if the temperature is elevated but, it is necessary that the oil not be dried before the reaction is complete.
• the reaction may also be carried out at room temperature and it has been found that typically, such reaction will be complete at approximately three days. At about 60°C, approximately one hour is required for the reaction to be complete. At about 99°C, the reaction will be complete in approximately ten minutes.
• This invention is most preferably carried out on a plant scale by carrying out the pre-treatment process in a continuous fashion using a large reactor vessel.
• a vessel may be a tank having a capacity of about 9900 litres. In such a tank a feed rate of approximately 4000 litres per hour will provide a residence time of about 2.5 hours.
• the level of the contents of the reactor vessel may be controlled using methods and devices known in the art for controlling the feed rate to the vessel and the pumping rate of the contents of the vessel to the next stage of process.
• the reactor vessel will preferably have some agitation means such as a motorized paddle.
• the temperature of the aforementioned reactor vessel will be controlled so that it is maintained between 60°C and the boiling point of water (for example, at 82°C).
• Methods and devices for maintaining the temperature of the reactor vessel are well known.
• a circulating pump may be used to circulate the reactor vessel contents through a heat exchanger and the pump may be controlled according to the temperature of the reactor vessel.
• a recirculation loop through a heat exchanger will also serve to keep the contents of the vessel agitated.
• the reaction vessel may be fully vented and is operated at atmospheric pressure.
• the rate of addition to the oil of the alkali metal reagent is continuously adjusted to maintain an ideal stoichiometric relationship.
• the oil treated in the reactor vessel may be analyzed after leaving the reactor vessel by ICP emission spectroscopy for calcium, magnesium, zinc, and sodium content and the amount of reagent added is adjusted so as to maintain the desired stoichiometric relationship.
• Sodium hydroxide is often preferred for its availability and low cost.
• a mixture of sodium hydroxide and sodium sulphide may also be used with the sodium sulphide being provided in the re-refining plant as a byproduct of a hydro-treating step.
• the oil that been subjected to the pre-treatment process of this invention may be distilled and the distillates therefrom may be subjected to other processes such as hydro-treatment.
• example 2 The method of example 2 was repeated except that 1% of calcium hydroxide was added to the oil rather than sodium hydroxide. In this case, the pH of the distillate was ⁇ 1 and the glassware was fouled as in example 1.
• example 1 The method of example 1 was attempted on a plant scale with sodium hydroxide being added to plant feed oil.
• the plant feed oil was flash dried at 150°C before entering a wiped film evaporator.
• low distillate pH and plant fouling occurred.
• oil from the flash dehydration unit was taken from the plant and distilled according to the method in example 1, the resulting pH was 1-2 and the glassware showed blackening.
• the difference in conditions between this example and example 1 was that in this case the oil that was treated with sodium hydroxide was subjected to flash drying (almost instantaneous drying) in the plant whilst the oil in example 1 had been boiled dry over a period exceeding 10 minutes.
• the process of this invention is time and temperature dependant; is ineffective when a basic reagent such as calcium hydroxide is used; and, requires the presence of water to proceed. This indicates that the mechanism of this process is not the neutralisation of sulphuric acid produced in distillation but rather the prevention of a reaction in which the sulphuric acid is formed.
• Detergent additives used in the formulation of motor oils typically contain di-basic metals (e.g. calcium, magnesium,and barium salts of aromatic sulphonic acids of the general formula (using calcium as an example):
• the process of this invention appears to involve an ion exchange reaction in which di-basic metal sulphonates are converted to alkali metal sulphonates.
• the ideal stoichiometric relationship in this invention is determined according to the predominant di-basic metals present in waste oil but not all of such metals are necessarily present in the form of sulphonates.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Forging (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 1992
  • 1992-05-19 CA CA002068905A patent/CA2068905C/en not_active Expired - Lifetime
• 1993
  • 1993-05-05 DE DE0600055T patent/DE600055T1/de active Pending
  • 1993-05-05 DE DE69312649T patent/DE69312649T2/de not_active Expired - Fee Related
  • 1993-05-05 AT AT93911712T patent/ATE156184T1/de active
  • 1993-05-05 EP EP93911712A patent/EP0600055B1/en not_active Expired - Lifetime
  • 1993-05-05 ES ES93911712T patent/ES2107029T3/es not_active Expired - Lifetime
  • 1993-05-05 DK DK93911712.3T patent/DK0600055T3/da active
  • 1993-05-05 JP JP5519726A patent/JP2928639B2/ja not_active Expired - Lifetime
  • 1993-05-05 WO PCT/CA1993/000193 patent/WO1993023506A1/en active IP Right Grant
• 1997
  • 1997-09-02 GR GR970402240T patent/GR3024596T3/el unknown

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