Mineral oils: processes and products – Refining – Purifying used oil
Reexamination Certificate
2001-08-13
2004-03-30
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Refining
Purifying used oil
C208S179000, C208S180000, C208S181000, C208S186000
Reexamination Certificate
active
06712954
ABSTRACT:
The present invention relates to a method for reprocessing waste oils, whereby waste oil is treated by means of distillation and extraction method, base oils obtained according to said method and their use thereof.
These days, disposal of waste products is becoming increasingly more important, in particular the elimination of environmentally noxious substances, such as halogenated hydrocarbons, aromatic compounds and similar. These represent acute and latent risks to human health and to other environmental resources, such as water, soil, air, plants and animals. In order to evaluate the actual risk potentials, it is necessary to examine and appraise material compounds and their concentrations. Such data serve as basis for type and scope of the disposal measures that need to be taken.
Of immense interest is hereby the disposal of products burdened with noxious substances, which occur in larger volume, such as waste oils, for example. Disposing these can be done either by elimination of the loaded products or by utilization of same, whereby utilization is basically to be preferred.
Utilization is generally possible via two routes: the product can be materially utilized, i.e., it can be reprocessed, or it can be utilized energetically as fuel. Certain criteria must be observed in such endeavor, which depend upon the product involved and the respective noxious matter burden.
Waste oils, for example, are subject to the so-called Waste Oil Ordinance (AltöIV) of Oct. 27, 1987, which regulates the reprocessing, registration, identification, collection and disposal of waste oils. Waste oils to be reprocessed are, as a rule, prohibited from exceeding a maximal value of 20 ppm of polychlorinated biphenylene (PCB) and a total halogen content of 0.2%. Exceptions, however, are quite possible, depending upon the chosen reprocessing method. Several methods for reprocessing of waste oils or of used oils are known in the state of the art. U.S. Pat. No. 4,021,333 from the year 1977 describes, for example, a method for reprocessing waste or used oils, which includes the following steps:
A) Distillation of the oil for eliminating a pre-fractionation with a viscosity essentially below that of lubricating oil and a flash point below 121° C., ascertained according to the Tag or Pensky-Martens method;
B) Continued distillation in order to obtain a distillate having, in essence, the viscosity of lubricating oil;
C) Extraction of impurities from the distillate of step B) with an organic, liquid extraction agent, which is essentially non-mixable with the distillate, and
D) Segregation from the distillate of the organic solvent and the impurities dissolved therein.
Named as organic extraction agents, are in particular: ethanol, diacetone-alcohol, ethylene-glycol-mono(low-alkyl)ether, diethylene-glycol, diethylene-glycolmono(low-alkyl)ether, o-chlorophenol, furfural, acetone, formic acid, 4-butyrolacetone, low-alkyl-ester of low mono-and dicarbonic acids, dimethylformamide, 2-pyrrolidone and N-(low-alkyl)2-pyrrolidone, epi-chlorohydrin, dioxane, morpholine, low-akyl- and amino(low-alkyl)morpholine, benzonitrile and di-(low-alkyl)sulfoxide and phosphonate. Preferred extraction agents are ethylenglycol-monomethyl-ether, dimethylformamid or N-methyl-2-pyrrolidone. In addition, in step C), 20 to 50 parts by weight of e on agents are employed for 100 parts of weight of obtained distillate from step B).
Distillation is to be performed without fractionating column or similar equipment. It is possible to remove, in a prior step, bothersome components, by means of a thinning agent, in form or an organic solvent, which step, additionally, may be preceded by heating the waste oil with a watery, highly alkaline solution. This method, however, does not always produce satisfactory results with respect to the quality of the reprocessed oils, which contain as before, light loads of noxious substances after the reprocessing.
The present invention is therefore based on the object of further improving the initially described method so that the obtained base oils have the lowest possible load of noxious matter, such as aromatic compounds and specifically polycyclic aromatic hydrocarbons. In addition, design of method control and potential starter materials should be flexible. At the same time, notwithstanding high quality of the obtainable base oils, good yields should be attained.
According to the invention, the above object is solved by a method for reprocessing of waste oils and production of high grade base oils comprising the following steps:
A) Distillation of the waste oil for removal of low-boiling organic fractions, as well as drying of the waste oil by removal of water
B) Distillation of waste oil obtained according to step A) under vacuum for separation of fuel oil and diesel fractions, with boiling cut of approximately 170 to 385° C., in form of high-grade heating fuels;
C) Non-destructive distillation of the distillation residue from step B) by means of thin-film evaporation in high vacuum for obtaining a lubricating oil fraction with a standard viscosity range, which may be followed, if needed, by a subsequent distillative fractioning step, possibly under vacuum, which can be divided into boiling fractions of different viscosity states;
D) If applicable, non-destructive distillation of the bottom product from step C) for obtaining a lubricating oil fraction of higher viscosity state from the higher boiling range, which, depending upon requirement, can be divided into a subsequent distillative fractionating step, possibly under vacuum; and
E) Extraction of fraction or fractions in the form of lubricating oil fractions or boiling cuts of different viscosity from step C) and, optionally from step D) with N-methyl-2-pyrrolidone (NMP) and/or N-formylmorpholine (NMF) as extracion agent for obtaining extremely high grade base oils, whereby the extraction is undertaken in such manner that undesirable constituents are removed in almost quantitative manner and the contents of polycyclic aromatic hydrocarbons (PAK) and polychlorinated biphenylenes (PCB) respectively, is clearly below 1 mg/kg.
The term “waste oil” in the present invention shall have the meaning of any used semi-liquid or liquid substance, which is comprised in total or in part of mineral oils or synthetic oils, as well as any oil containing residue, including water-oil mixtures or similar. Thus, it is possible to use all waste oils suitable for reprocessing into lubricating oils, in particular used combustion engine and transmission oils, mineral machine oils, turbine oils and hydraulic oils, including their synthetic and semi-synthetic constituents or mineral hydrocarbon basis.
The inventive method for reprocessing said waste oils is described in detail below:
In a first step A), water fractions as well as fractions of low boiling constituents are distilled off, such as fractions of gasoline or solvents. This is preferably done at normal pressure or under light vacuum (up to approximately 600 mbar) at a temperature of approximately 140 to 150° C.
It is possible to facultatively employ in the inventive method, in particularly beneficial manner, a concentrated watery potassium hydroxide solution. Said solution is already employed in this first step in order to avoid, during subsequent distillation steps, additionally burdening generation of the vacuum with water to be separated from the potassium hydroxide solution. The potassium hydroxide solution is preferably highly concentrated, specifically approximately 5 to 50% .
At the same time one obtains, by means of the dehydration process executed in the initial step A), the concentration of the potassium hydroxide as an extremely homogeneously distributed, highly concentrated and therefore highly effective acting reagent for binding acid constituents in the charged waste oil, including extensive demetallization of the charged waste oils. Furthermore, the use of potassium hydroxide solution, which causes formation of specific “soaps”, produces in the subsequently described thin film evaporation in step C), a pa
Bruhnke Detlev
Hindenberg Holger
Mödler Michael
Pöhler Joachim
Fay Sharpe Fagan Minnich & McKee LLP
Griffin Walter D.
Mineralöl-Raffinerie Dollbergen GmbH
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