EP0690903B2 - Process and plant for the regeneration of lubricating oils - Google Patents

Abstract

Process and plant for the regeneration of spent oils comprising: a tank (2) for the storage of spent oils; preheating means (3) for the preheating of spent oils; means (4) for the storage of a strong base; means (5) for mixing the strong base in a predetermined proportion with the spent oils; waste elimination means (10, 14).

Description

The invention relates to a method and an installation for regenerating used lubricating oils.

Lubricating oils generally undergo modifications and alterations during their use, which implies their more or less frequent renewal.

The elimination or regeneration of these used oils has so far been a major source of pollution.

After use, these oils generally contain solid residues, additives, combustion residues, etc ....

Various recovery methods have been developed so far. Degraded oils are first recovered and these oils of various origins are sometimes mixed with more or less foreign products likely disrupt regeneration processes.

Up to now, the most used processes include a step of treating used and recovered oils with sulfuric acid then their neutralization with lime and sodium carbonate and finally bleaching with activated earth and filtration.

We know in particular the installation and the method described in document GB-A-243,666. This installation includes two tanks, allowing two treatments, one with soda and the other with the ground, and two centrifuges, ensuring the separation, one of water and the other of used earth, of the oil to be treated.

This type of process allows the recovery of part of the used oils, but generates non-reusable waste highly polluting.

The recovery rate of industrial installations implementing these processes does not exceed 85% and their cost of implementation is high.

We also know other recovery processes based on hydrofinishing the oil after heat treatment and its vacuum distillation. The hydrogenation of the oil is produced by hydrodesulfurization catalysts and hydrodenitrogenation

During the implementation of these processes, the catalysts are gradually exhausted and finally give birth of highly polluting non-reusable products.

Furthermore, these methods are even more expensive.

We still know the process described in document GB-A-2,022,131. In this process of regenerating oils used a first phase of dehydration and elimination of chlorinated hydrocarbons is carried out in the meantime between 100 ° and 200 °. Then an alkaline treatment is carried out in a closed system at at least 200 ° C with a mixture of soda and potash. Thermal vacuum distillation reaching a temperature of 480 ° C then takes place.

The objective of the present invention is therefore the development of a process for the regeneration of lubricating oils little or non-polluting used and whose implementation can be done in good economic conditions.

It is also an object of the present invention to provide a process for regenerating used oils allowing a high oil recovery rate.

To this end, the invention relates to a process for regenerating used lubricating oils comprising a step strong base treatment.

According to the invention, the method comprises the steps of successive object processing of claim 1.

• La colonne de distillation sous vide coopère avec un évaporateur d'épuisement de fond de colonne.

In a preferred embodiment, the invention comprises the following characteristic:

• The vacuum distillation column cooperates with a column bottom exhaustion evaporator.

The invention also relates to an installation for regenerating used oils allowing the implementation of the process mentioned above.

This installation is the subject of claim 3.

Preferably the vacuum distillation unit is associated with a column bottom exhaustion evaporator.

An embodiment of the invention will be described in more detail with reference to the single Figure which is a representation schematic of the installation for regenerating used oils according to the invention.

The used oils collected can have various origins, it can be for example engine oil, oil gears or hydraulic oil, turbine oil, etc.

When these oils arrive at the regeneration unit, their suitability for processing is checked.

Indeed, the regeneration process of the invention essentially aims at the elimination of light components, such like gasoline, diesel and water, but cannot remove components as heavy as the oils themselves but having different physical properties. It could be, for example, fuel whose elimination or treatment could only be obtained by a complete refining process.

Excessive chlorine content in mixtures may cause premature wear of the installation.

Collected oils therefore containing too high a percentage of fuel, fatty acid or chlorine should be eliminated. In order to assess the concentrations of these various compounds, tests well known in them are practiced. same in use in the field.

Among these may be mentioned the "Chlor Test" which makes it possible to detect the presence of chlorides. A hardened copper wire in used oil is presented to the flame. A greenish flame indicates the presence of chlorides.

The "Drop Test" detects the presence of fuel. A drop of oil is deposited on a chromatographic paper. A concentric spot with a yellowish halo indicates the presence of fuel.

The "Fat Test" detects the presence of fatty acids in oils. 2 ml of used oil is heated in presence of a soda tablet: when the oil freezes, after cooling, this means that fatty acids are present.

The waste oils collected 1 having successfully undergone these various tests are combined in a tank 2.

They are then mixed either inside the tank itself, or during their extraction by conventional means not shown in the Figure.

Preheating means 3 bring the oils taken from the tank 2 to a temperature between 140 and 160 ° C.

A base stored elsewhere in a tank 4 is supplied and mixed by means 5 with the used oils. preheated.

A quantity of pure base of between 1 and 3% by mass is added to the used oils.

This rate can advantageously be specified as a function of the quality of the used oils.

Used oils, brought to a high temperature, added with a strong base, feed an extraction unit 6 water and light hydrocarbons by flash (flash). In such a unit, evaporation of water is produced by the sudden expansion of the mixture in a balloon.

Water and light hydrocarbons are extracted and the remaining mixture is directed to a unit 8 for extracting diesel (stripping). This elimination is carried out by distillation in a column.

The gas oil 9 is then discharged and the remaining mixture is led to a distillation column 10 allowing the fractionation of the mixture into lubricating base oil sections and separation of the residue where all are concentrated the impurities.

Base oils can be separated at different levels depending on the number of cuts desired.

Good results have been obtained by separating, on the one hand, a base oil of 150 Neutral 11 and a base oil from 400 to 500 Neutral 12.

The distillation column 10 is a traditional vacuum column which allows the dissociation and the extraction of the residues, which are directed to an accumulation tank 14.

The residues 15 are then removed and are capable of being used, for example, as tar or bitumen for road construction. They can also be used as fuels.

The vacuum distillation column 10 is preferably associated with a bottom exhaustion evaporator. column 13 to improve its efficiency. Part of the energy required to raise the temperature used oils before the addition of the pure base preferably comes from the energy recovery carried out on the lubricating base oil sections 11, 12 of the column outlet 10.

The used oils are advantageously filtered during their recovery and when they leave the tank. storage 2, so as to eliminate the solid particles which they may contain.

Different pumps not shown ensure the circulation of the mixture and the extracted products through the installation described.

The process and the installation of the invention therefore make it possible, from used oils, to obtain base oils of various reusable qualities, usable residues, water, light hydrocarbons and diesel.

All the products obtained are therefore reusable, which is why this process makes it possible to avoid main pollution risks.

This process provides a minimum recovery rate of 90%. This rate is the mass ratio of quantities of oils recovered by this industrial process, compared to that of oils recovered in the laboratory, in optimum conditions independent of any economic consideration.

However, the preferred embodiment uses the vacuum distillation column associated with an evaporator column bottom exhaustion. It is thus possible to obtain an oil cut recovery rate of excellent lubricant base, lower investment and operating costs compared to other processes known regeneration, to obtain regenerated oils as efficient as new base oils and to eliminate of these almost all metals.

In addition, all the impurities are contained in their residues which, as already indicated, are easily recoverable.

The installation of the invention can be implemented easily under the best conditions of reliability.

The following numerical example illustrates the implementation of the invention.

In a), the result of the vacuum distillation of the used oils in the laboratory was indicated by providing the components and their precise characteristics.

In b), the result of the distillation obtained by a previous process, without the addition of base, is shown. This process must, according to the prior art, be followed by the chemical finishing treatment, by a traditional acid process and to the earth whose disadvantages have been indicated above. The results of this treatment are shown in c).

In d), the regeneration of the oils is shown according to the industrial process claimed.

In these different tables, the products are the components recovered.

Yield represents their yield (Mass ratio of the quantity recovered compared to the initial quantity of oil used to regenerate).

T.A.N. represents their acidity (acid number content).

VIS 40 ° C represents their viscosity at 40 ° C expressed in centistocks.

Color is expressed relative to standard reference colors. Plus the numeric value shown is weak, the better the color and appearance is a qualitative indication.

Ba represents barium, Ca calcium, Pb lead, Zn zinc, P phosphorus, Cr chromium, Fe iron and Si silicon.

Comparison of table c) with table d) highlights the superior quality of the cuts of base oils obtained according to the invention. In particular, the metal contents in the recovered oils are much lower and the yield is more important. In addition, all of the cups are easily reusable.

The engine tests of the oils regenerated according to the invention have shown their equivalence to new oils. They are more efficient than those regenerated by known methods.

The reference signs inserted after the technical characteristics mentioned in the claims, have the sole purpose of facilitating the understanding of the latter, and in no way limit their scope.

Claims (3)

1. A method of regenerating used lubricating oils characterised in that it includes the following successive treatment steps :

   a) homogenisation of the collected oils and removal of them when they do not satisfy one of the following tests:

   test for chlorine with a flame (chlorine test),

   test for the presence of fuel oil by the drop test,

   test for the presence of fatty acid with caustic soda (fat test);

   b) pre-heating in which the oils to be regenerated are brought to a temperature between 140° and 160°C;

   c) addition of sodium hydroxide in aqueous solution at an amount of 1 to 3% of pure base, based on the mass of lubricating oil;

   d) dewatering and extraction of the light hydrocarbons by pressure reduction (flash),

   e) extraction and recovery of gas oil (stripping);

   f) extraction of the impurities by fractional distillation under vacuum providing the separation of the base lubricating oils on the one hand and of a residue that concentrates all the impurities on the other hand.
2. A method of regenerating used lubricating oils according to claim 1, characterised in that the column for the vacuum distillation works with an evaporator that drains the bottom of the column.
3. An installation for the regeneration of used oils comprising:

   a storage reservoir (2) for the used oils,

   means of mixing and homogenising the oils that are initially contained in the storage reservoir (2),

   means (3) of preheating the used oils taken in the storage reservoir (2) to a temperature between 140° and 160°C,

   means (4) of storing pure sodium hydroxide,

   means (5) of mixing sodium hydroxide in a specific proportion between 1 and 3% based on the mass of the used oils,

   a unit (6) for the extraction of the water and the light hydrocarbons by pressure reduction (flash) of the used oils at a high temperature added with pure sodium hydroxide,

   a unit (8) for the extraction of the gas oil (stripping), and

   means (10, 14) of extracting impurities including a vacuum distillation unit (10);

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