EP0690903B1 - 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 a lubricating oil regeneration plant used.

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

Elimination or regeneration of these oils waste is a source of pollution so far important.

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

Different recovery processes have been developed so far. Degraded oils are firstly recovered and these original oils various are sometimes mixed with more or less foreign likely to disrupt regeneration processes.

So far the most used processes include a step for treating used oils and recovered by sulfuric acid then their neutralization with lime and sodium carbonate and finally the activated earth discoloration and the filtration.

We know in particular the installation and the process described in document GB-A-243.666. This installation includes two tanks, allowing two treatments, one to the soda and the other to the earth, and two centrifuges, ensuring the separation, one of the water and the other of the used earth, oil to be treated.

This type of process allows the recovery of a part of the used oil, but generates waste not reusable highly polluting.

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

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

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

Furthermore, these processes are even more expensive.

We still know the process described in document GB-A-2.022.131. In this regeneration process used oils a first phase of dehydration and elimination of chlorinated hydrocarbons is carried out in a temperature range between 100 ° and 200 °. Then an alkaline treatment is carried out in a closed system at least 200 ° C with a mixture of soda and potash. A thermal vacuum distillation reaching a temperature of 480 ° C. is then carried out.

The objective of the present invention is therefore the development of an oil regeneration process used lubricants with little or no pollution and the use of which can be done in good conditions economic.

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

To this end, the invention relates to a method of regeneration of used lubricating oils comprising a strong base treatment step.

According to the invention, the method comprises the steps of successive treatments object 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 of regeneration of used oils allowing the setting in work of the process mentioned above.

This installation is the subject of claim 3.

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

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

The used oils collected may have various origins, it can be for example engine oil, gear oil 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 eliminating light components such as than gasoline, diesel and water, but does not allow to remove components as heavy as the oils themselves but having different physical properties. he could be, for example, fuel whose elimination or treatment could only be obtained by a process of complete refining.

Excessive content of chlorine mixtures could be likely to cause premature wear of the installation.

Oils collected therefore containing a percentage too much fuel, fatty acid or chlorine should be eliminated. In order to assess the concentrations of these different compounds, we practice the tests well known in themselves in use in the field.

Among these we can cite the "Chlor Test" which allows to detect the presence of chlorides. A hardened copper wire in used oil is presented to the flame. A flame greenish indicates the presence of chlorides.

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

The "Fat Test" detects the presence of acids fat 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.

Used oils collected 1 having successfully undergone these different tests are combined in a tank 2.

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

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

A base stored elsewhere in a tank 4 is added and mixed by means 5 with waste oils preheated.

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

This rate can be advantageously specified depending on the quality of used oils.

Waste oils, brought to a high temperature, added with strong base, feed a unit 6 extraction of water and light hydrocarbons by expansion (flash). In such a unit, the 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 diesel 9 is then evacuated and the remaining mixture is leads to a distillation column 10 allowing the fractionation of the mixture into base oil cups lubricants and the separation of the residue where concentrated all the impurities.

Base oils can be separated at different levels according to the number of cuts sought.

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

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

The residues 15 are then removed and are susceptible to be used for example as tar or bitumen for the road construction. They can also be used as fuel.

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

Used oils are advantageously filtered during of their recovery and when they leave the reservoir of storage 2, so as to eliminate solid particles that they can contain.

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

The method and the installation of the invention allow therefore 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, this is the reason why this process makes it possible to avoid main risks of pollution.

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

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

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

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

The following numerical example illustrates the implementation of the invention.

In a), the result of the distillation is indicated under empty used oils in the laboratory by supplying components and their precise characteristics.

In b), we represent the result of the distillation obtained by a previous process, without addition of base. This process must, according to the prior art, be followed by the treatment chemical finishing, by a traditional acid 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 represented according to the industrial process claimed.

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

Yield represents their yield (Mass report 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.

The color is expressed in relation to colors of standard reference. The higher the numerical value indicated 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.

The comparison of table c) with table d) makes bring out the superior quality of the base oil cuts obtained according to the invention. In particular the contents in metals in the recovered oils are very inferior and the yield is more important. Plus all of the cuts is easily reusable.

Engine tests of regenerated oils 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 (4)

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 the rate of 1 to 3 % of pure base, to 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,

   means (3) of preheating the used oils 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 % by mass of the used oils,

   a unit (6) for the extraction of the water and the light hydrocarbons by pressure reduction (flash),

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

   means (10, 14) of extracting impurities including a vacuum distillation unit (10).
4. An installation for the regeneration of used oils according to Claim 3, characterised in that the unit for the vacuum distillation (10) is linked to an evaporator (13) that drains the bottom of the column.

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