WO2014154923A1

WO2014154923A1 - Improved flash column and method for regenerating used mineral oil

Info

Publication number: WO2014154923A1
Application number: PCT/ES2014/070222
Authority: WO
Inventors: Ricardo VILAPLANA PÉREZ
Original assignee: Kay & Rober Ingenieros, S.L.
Priority date: 2013-03-25
Filing date: 2014-03-25
Publication date: 2014-10-02
Also published as: MA38424A1; ES2498719A1; ES2498719B1; MA38424B1

Abstract

The method is divided into six steps: dehydration, pre-treatment, extraction of glycols and other hydrocarbons, extraction of spindle oil, distillation of light and medium lubricating base oil, and distillation of heavy oil. The distillation steps are carried out using the improved flash column (1) of the invention, including a downward cyclone evaporation pre-chamber (10) having a gradually increasing cross-section, and a cyclone separator (14) at the outlet. The novel design of the reflux-free distillation column allows the use of high vacuum conditions, up to 0.5 mbar, and, consequently, the temperatures of the product to be distilled are substantially lower than with current distillation devices. The absence of reflux and of contact elements inside the column allows the used oil to be pre-treated with a sufficient quantity of a basic solution in order to obtain distilled base oils that require no final treatment.

Description

DESCRIPTION

IMPROVED FLASH COLUMN AND PROCEDURE TO REGENERATE OIL

USED MINERAL

Object and Field

The present invention relates to a process and equipment for regenerating used mineral oil, simply, economically and efficiently.

Its field of application is the recovery and regeneration of used mineral oils (industrial and automotive). More specifically, the treatment that allows to remove contaminants from used mineral oil and produce regenerated base oil for the formulation of new lubricants and industrial products.

The present invention also relates in general to the distillation of used lubricating oils, crude oil and hydrocarbon mixtures. More specifically, to the distillation of used oils for recovery as base oil or fuel.

Background of the invention

The new lubricating oils contain approximately 85% base oil and 15% of additives of varied composition, depending on the application to which they are intended.

During its use, the oils undergo two types of alterations, on the one hand the concentration and variation of the additives that accompany it and on the other hand, the process itself, the fuel, the environment, add water, sediments, oxidized products, etc. .

A used motor oil broadly presents the following qualitative composition:

Hydrocarbons of three types or provenances: Light from pollution

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REPLACEMENT SHEET (RULE 26) For gasoline, diesel from those engines that use this fuel and base oil.

Water from combustion or pollution.

· Sediments that will be formed by: Metals of wear of moving parts of motor or lubricated equipment, unburned from fuels and dust.

They also have a variable content of a series of metallic and non-metallic elements that come from the additives that are initially incorporated into the oil and others added artificially or accidentally.

The base oil of used lubricants does not wear out. The chains of paraffinic, naphthenic and aromatic hydrocarbons of which the base oil of the lubricants is composed remain unchanged during the life of the lubricant. The regeneration process removes additives, dirt and contaminants, leaving a lubricating base oil of the same characteristics as those obtained by refining crude oil.

Each year, about 40 million tons of lubricating oils are marketed worldwide. These lubricants, once they reach the end of their useful life, have to be replaced, generating millions of tons of used mineral oils every year.

At present, most of this hazardous waste is energy recovered in boilers and industrial furnaces. An important part of this type of facility does not comply with environmental restrictions in terms of emissions, transferring contaminants from used oil to the environment.

Although the regeneration of used mineral oils is the priority treatment in the European Union, in most developed and developing countries it is not. Therefore, it is basically economic aspects that establish the type of main management of used oil, combustion versus regeneration. Only a small percentage of the used lubricating oil produced is regenerated in the world.

The first data on the regeneration of used oils date from the early 1900s in Europe, where low oil production and high import costs of

REPLACEMENT SHEET (RULE 26) They pushed oil recovery.

During the Second World War the sector experienced a boom due to a shortage of base oil supply. The regeneration processes used until the late 1970s used sulfuric acid and bleaching earth to remove contaminants from used oil, generating large amounts of highly toxic acid residues. The hardening of environmental laws in industrialized countries has led to acid treatment in decline. To solve the aforementioned problems, and by the same dates, various regeneration processes are developed based on one or several fractional distillations. Thus, US 3,173,859 proposes a first initial distillation and a second final distillation separated by an intermediate treatment, while US 3,879,282 describes a process using a conventional flash column distillation preceded by a pretreatment with a strong base, and followed of a final treatment to obtain the desired characteristics of the different products. This last document constitutes the beginning of a development line that leads to the present invention.

At present, the regeneration industry uses different processes that alternate basic operations such as dehydration and distillation with pretreatment and finishing stages.

Pretreatment The common pretreatment in the processes of regeneration of used oils consists in the decantation of water and filtering. Some processes also incorporate the neutralization of the oil with a strong base and / or the extraction of contaminants with liquid propane.

The addition of a strong base to the oil is a simple, economical and effective method to pre-treat the used oil, prior to distillation operations. In most of the processes the base is incorporated into the oil before being subjected to dehydration, thereby diluting the base and proportionally the desired effects of pretreatment. The reaction time of the mixture and the temperature are not adequate in most cases. On the other hand, the processes that currently use pretreatment with

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REPLACEMENT SHEET (RULE 26) alkali, they incorporate insufficient amounts to cause the desired reactions. Of all the contaminants in used oil, oxidative degradation products make up the largest portion. Therefore, the degree of refining of a regenerated base oil is measured based on the percentage of oxygenated compounds present in it. To remove all oxygenated compounds from a used type oil, it is necessary to add an amount 13 times higher than necessary to neutralize the acidic compounds found in the used oil. Although in the patents describing regeneration processes in which the pretreatment with a 50% basic solution is incorporated, the amounts established vary between 0.2% and 10%, the operational reality of the current plants they use Said pretreatment is that they use amounts less than 3%. The reason is that the formation of metal salts, product of the reactions of the alkali with the oil contaminants, produces an increase in viscosity proportional to the amount of base added, which causes additional obstructions and fouling in the internal structures and reflux circuits of the evaporators and distillation columns currently used.

US Patents 6,398,948 ^and B1, US 7,267,760 and EP N ^and 1,171,554 B1, disclose a method for removing contaminants from used oil, using a phase transfer catalyst to facilitate the transfer of an organic base or inorganic to the oil substrate. In particular, the preferred catalyst in the application of said patent is glycol. It is known that phase transfer catalysts can be used to accelerate the rate of reactions between two chemical species that are initially present in different phases. In the case of the reactions between a basic solution and the oil used, other variables such as the contact time, the homogeneity of the mixture and the temperature thereof are more decisive. If these variables are set correctly, it is not necessary to add a catalyst in the pretreatment of the oil with a basic solution. In any case, the used lubricating oils from which the regeneration plants are supplied, incorporate on average 3% glycols, due on the one hand to the contamination of the oil with the engine coolant and on the other to the components used in the manufacture of synthetic oils (currently the commercialization of synthetic oils accounts for 10% of total lubricant sales). This amount would be more than enough to accelerate, if necessary, the reactions of the basic solution with the oil. Therefore, if a minimum reaction time is established in a reactor with sufficient stirring to homogenize the mixture and the

REPLACEMENT SHEET (RULE 26) suitable temperature to promote the reactions, the addition of a phase transfer catalyst becomes unnecessary and accessory, which on the other hand already incorporates the used oil that is used as raw material for the regeneration plants. Distillation

One of the main problems posed by the regeneration of used lubricating oils concerns their distillation. This is the severe fouling of the equipment, due to the combination of the amount of contaminants carried by the used oil along with the high heating temperatures used. These two variables give rise to reactions of thermal cracking and thermal degradation of the most unstable compounds, which cause the formation of coke inside the equipment. This results in maintenance costs, decreased equipment efficiency and low quality of distillates, which require a final treatment to be marketed.

Current used oil recovery processes use evaporators and / or distillation columns in the distillation stages to separate the base oils from their contaminants. Evaporators

There are numerous processes of regeneration of used oils in which thin film evaporators (TFE) are incorporated in the distillation stages. The film evaporator is basically composed of a cylindrical evaporator body, placed vertically and heated by a heating jacket, and a rotor with fins inside. The product to be treated is introduced above the heating jacket and the rotor fins take it and spread it like a thin film on the heating wall. Due to gravity, the product slides down evaporating at the same time. The produced vapors run the device upstream. These teams have several drawbacks. On the one hand its high acquisition cost. On the other hand, it must be taken into account that the rotor is a moving part composed of a shaft, bearings, bushings and mechanical seals to guarantee the tightness of the equipment in conditions of high vacuum and high temperatures. This translates into costly periodic maintenance operations and a potential source of mechanical problems. Finally, the inevitable fouling of

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REPLACEMENT SHEET (RULE 26) Evaporator and rotor body, forces to stop the process to perform cleaning operations, which most often include the removal of the rotor.

US Patent N ^and 5,814,207, describes a method of regenerating the used oil employing a cyclonic vacuum evaporator distillation steps. Said patent describes the evaporator as "a cyclonic vacuum evaporator comprising a substantially empty evaporation chamber in which the feed is injected tangentially, and in which a fraction of the feed condenses into a mixing condenser communicated with the mixing chamber. evaporation". The aforementioned patent does not present any detailed drawing of the aforementioned evaporator nor does it explain how it avoids dragging and contamination of coke and drops of used oil to the condenser. Additionally, the distillates obtained with this method may contain volatile compounds, unstable sulfur compounds and decomposition products of the additives. Therefore, the implementation of a final treatment is contemplated in the patent itself.

PCT WO 91/17804 describes N ^and a cyclonic vacuum evaporator improved distillation of waste oils. The inside of the evaporator contains a number of concentric cones mounted on each other, which serve to provide a reflux action. In the upper part of the evaporation chamber it incorporates a mixing condenser in which the distillate is condensed.

PCT patent WO 92/15659 describes a method for regenerating used lubricating oil and an apparatus for applying this method. The evaporator described in this patent contains an inner jacket through which the vaporized oil and used oil circulate in a liquid state. The regeneration method described in this patent includes settling tanks for the distillates obtained in order to separate the entrained particles during evaporation. Additionally, the distillates obtained in the distillation stage require an expensive final treatment with hydrogen.

US Patent No. 4140212 ^and describes a cyclonic column distillation for distillation of waste oils. The described column contemplates a series of interior structures to channel the flow of steam and liquid, as well as a lower structure to separate the column into two halves, with a connecting duct of both halves to equalize the pressures.

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REPLACEMENT SHEET (RULE 26) The liquid enters the column by means of a tangential nozzle.

US Patents 6,398,948 ^and B1, US 7,267,760 and EP N ^and 1,171,554 B1 disclose a process using an evaporator to separate oil into three fractions. The aforementioned patents do not present any detail plan of the above evaporator nor explain how to avoid the dragging and contamination, of coke and drops of used oil, to the respective condensers. The only graphic provided in these patents is a very basic process scheme in which the evaporator for the distillation of used oil is represented as a distillation column with three outlets.

The main disadvantages of the evaporators described in US Patent 5,814,207 ^and N, N ^and PCT WO 91/17804, PCT WO 92/15659 and US 4,140,212 N ^and are the soiling of the structures and formation of coke deposits of carbonaceous particles, and coke traps and drops of used oil to the condensers.

For evaporators described in US Patent 5,814,207 and PCT N ^and WO 91/17804 ^and N, presented fouling distillate collection tray and duct obstruction output thereof to the distillate reception tank, and fouling and clogging of the showers of the mixing condenser. Additionally, condensation by mixing condenser inside or outside the evaporator itself continuously contaminates the distillate, passing through it all volatile compounds, oxidation compounds, sulfur unstable compounds and other thermal decomposition compounds of additives In the case of the cyclonic column described in US Patent ^and 4140212, the inlet nozzle of the oil to the column would obstructing coke formation and deposits of carbonaceous residues over hours, reduced viewing performance if of some days. The pressure equalization duct is also a potential source of fouling and obstruction problems.

All these problems lead to frequent stops to clean the equipment. Additionally, the distilled oils obtained in the evaporators described in the previous patents require an expensive final treatment.

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REPLACEMENT SHEET (RULE 26) Distillation columns

The design of the distillation columns that are used in some used oil regeneration processes, comes from the oil refining industry. In most cases they are packed columns, washed with a high flow rate of the reflux liquid to prevent premature fouling of the gasket. The pressure drop in this type of columns is not negligible, so in order to distill the heavier components, it is necessary to heat the oil to a temperature above 350 ^e C. At these temperatures the cracking of the most unstable compounds It is high, producing thermal degradation and coking of them. This results in maintenance stops and more periodic cleaning. As a result of the reflux of the different distillation cuts obtained, and the large contact area offered by the packed columns, it becomes necessary in all processes that incorporate this type of equipment, a final treatment of the distillates in order to comply with the market specifications.

Final treatment

All regeneration processes in operation today require a final treatment. The most commonly used are: hydrogenation (treatment conditions: 370 ^e C / 100 bar), hydrotreatment (treatment conditions 320 ^e C / 60 bar), extraction of contaminants with solvents and finally treatment with bleaching earth.

The first two require a high investment in equipment and have a high operating cost. In addition, in the case of hydrogenation, such severe pressure and temperature conditions break the linear chains of synthetic oils, preventing their recovery.

Solvent extraction treatments also have a non-negligible acquisition cost and also raise operational costs.

Finally, the treatment with land presents two important problems. On the one hand the generation of waste (oily lands) and on the other the decrease of the yield of the process by being retained in the spent lands a percentage by weight of oil between the

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REPLACEMENT SHEET (RULE 26) 50-100% Of course, operational costs are also increased by the purchase of bleaching land and waste management expenses.

With this background, it is compressible that the regeneration industry has not taken off, and has not become a true alternative to the combustion of used oils. Current processes are expensive to acquire and operate.

Consequently, it is an objective of the present invention to have a process whose acquisition cost is similar to that of a treatment plant for used oils for combustion, which does not generate waste, which is versatile and can alternatively regenerate or produce fuels with qualities that meet all market specifications.

It is another objective of the present invention to have a process of regeneration of used oils that is cost effective and does not produce toxic waste.

Description of the invention

To achieve the proposed objectives, the process of the invention has been developed, which separates acidic compounds, metal and organometallic compounds, spent additives, aromatic polynuclear hydrocarbons and separates or replaces hydrocarbons containing heteroatoms (chlorine, boron, phosphorus , sulfur, oxygen and nitrogen), from the used lubricating oil, obtaining odor-free and good-color lubricating base oils, which meet the requirements of the American Petroleum Institute established for the base oils of the Group l +.

This invention also relates to an improved flash column for the distillation of used oils under high vacuum, essentially maintenance free, without interior structures or reflux systems. This column can also be applied in other distillation or evaporation processes such as oil distillation or solvent recovery.

The essential component of the present invention is the use of the improved flash column in the distillation stages of the proposed process.

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REPLACEMENT SHEET (RULE 26) The improved flash column consists of a cylindrical body of varying height depending on the products and flows to be distilled, a torso-shaped bottom klopper welded at the bottom with an outlet pipe for the bottom product, a flange top cover for tasks for inspection and cleaning, a flanged side pipe at the top of the column, for the output of the vapors, a product inlet pipe to the column, connected to a cyclonic pre-chamber of descending evaporation whose section increases progressively according to the liquid travels along it, and tubing for instrumentation.

The product to be distilled enters the column through the cyclonic evaporation chamber, where the product begins to evaporate and the vapor-liquid separation begins, flowing the liquid stream through the lower zone and the vapor stream through the upper zone. The descending cyclonic shape of the prechamber creates a flow of liquid rotating down the wall of the column and a clean flow of steam rotating up. Both streams, vapor and liquid, separate from each other as they form, progressively. With this design, dragging due to instant evaporation is minimized. The absence of nozzles or other flow restriction devices at the column inlet, guarantees the stability of the equipment performance during its continuous operation, and a maintenance-free operation.

At the top of the column and below the steam outlet, a removable impact separator can be installed, if necessary, for particles up to 10 μηι in diameter. To avoid clogging the impact separator, a separator with zig-zag diverter plates with adequate spacing has been designed. In the outlet flange of the column vapors, a cyclone can be installed for the definitive separation of the droplets that could be carried by the steam, which advantageously incorporates a central pipe. This prevents condensed steam from becoming contaminated and a final treatment of distillates is necessary. The liquid collected in the cyclone returns by gravity to the column, below the entrance cyclonic chamber.

To avoid condensation of the vaporized product inside the column, which would lead to a reduction in process performance, it is necessary to maintain an adequate temperature inside the column. For this, a layer of

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REPLACEMENT SHEET (RULE 26) Insulation of rock wool or similar throughout the outer surface of the column and the outer cyclone, which minimizes heat losses. Additionally, an extra volume is available at the bottom of the column, which is kept full of hot product during the operation of the process. The heat itself that gives off the mass of hot product allows to maintain an adequate temperature inside the column avoiding undesirable condensations.

The enhanced flash column, with the exception of the removable impact separator where appropriate, has no interior structures (baffles), no fillers, no plates, no reflux systems. With this design it is possible on the one hand to be able to add all the alkali necessary to cause neutralization reactions without clogging the column, and on the other to obtain a clean and clear distillate, free of contaminants, which does not require a final treatment for its commercialization. The regeneration process object of the present invention consists of six differentiated stages which are: dehydration, chemical pretreatment, extraction of glycols and other hydrocarbons, extraction of spindle oil, distillation of light and medium base oil, and distillation of heavy base oil . The stages are designed to be built in a modular way, thus facilitating assembly at the destination. In the case of the stages of dehydration, glycol extraction, spindle oil extraction, light and medium base oil distillation, and heavy base oil distillation, the module is basically composed of an improved flash column adapted to the specific operation to be performed , vacuum system, heating system and condensation system. Although in the preferred process of this invention the improved flash column is used in all stages requiring vapor-liquid separation, in the stages of dehydration, glycol extraction and spindle extraction another type of column or evaporator could be used if desired. All the columns that incorporate the different stages have the same design. Only its dimensions vary, which are adapted to the working conditions and the products obtained in each of them.

This process can be operated in continuous or batch mode. In case of being operated by

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REPLACEMENT SHEET (RULE 26) Batches would require at least two improved flash column modules and the pretreatment module.

The sequence of the process in continuous mode is as follows: a) Dehydration of used oil.

The decanted and filtered used oil is sent to the dehydration stage by means of a pump. At this stage they are separated from used oil, water, gasoline and solvents. For this, the improved flash column of the invention is used. The oil is aspirated by a pump from the bottom of the column, sends a portion of the oil to the next stage of the process, and the rest is sent to a heat exchanger. The oil is heated in the heat exchanger at a temperature below 200 ^e C, to prevent coking. The preferred temperature range is between 140 and 150 ^e C. The oil leaving the exchanger is mixed with the feed inlet stream through a static mixer. The mixed current passes into the improved flash column. This way of heating the inlet stream by means of a recirculation system, in which the feed flow is mixed with a large amount of hot oil, reduces the tendency to coke of the most unstable compounds of the inlet oil. It also allows working with a high flow rate, which reduces the temperature differential, avoiding the transition and film boiling rates. The speed through the heat exchanger must also be high to avoid premature fouling. The speeds of the oil used inside the heat exchanger must be above 4.5 m / s, especially in the distillation stages. The mixed stream entering the dehydration column contains between 3 and 12% by weight of the feed stream. The vapors produced leave the top of the column and go to a condenser, preferably surface, where they condense. The condensate obtained is sent by gravity, to avoid emulsions, to a coalescing decanter where hydrocarbons are separated from water. The water thus obtained can be recycled, with minimal treatment, for use in the plant's cooling systems. The column works at atmospheric pressure or with a slight vacuum. The incondensables are captured by the extraction and purification system and sent to the plant's boiler for incineration, thus avoiding odor emissions.

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REPLACEMENT SHEET (RULE 26) The advantage of operating in the dehydration stage at moderate temperatures and atmospheric pressure is: obtaining water practically free of contaminants, which hardly requires a minimum treatment to be reused in the plant, and obtaining a fraction of light, suitable hydrocarbons to be used as fuel in furnaces and industrial boilers. b) Pretreatment with a basic solution.

The dehydrated used oil is sent, through a cooler / heat recuperator, to a process reactor equipped with an agitator, where it is mixed homogeneously with a basic, organic or inorganic solution, in order to achieve neutralization of the Acid compounds of the oil and the rest of the reactions that will help, along with the distillation stages, to remove the contaminants from the used oil. The basic solution is injected, by means of a metering pump, into the connection pipe of the dehydration stage with the reactor, and before a static mixer where a first mixture of the two streams is produced. In the reactor, the currents are still mixed at a temperature between 80 and 90 ^e C. The residence time therein will depend on the degree of contamination present in the used oil. Normally the contact time to cause the desired reactions can be between 30 and 90 minutes. With a proper sizing of the reactor volume a process is achieved in continuous mode. From the bottom of the reactor sucks a pump that sends the oil to the next stage. Due to its low cost and availability, the 50% concentrated sodium hydroxide solution is preferred. Although better results can be obtained with potassium hydroxide or other concentrated basic solutions. The amount of 50% concentrated sodium hydroxide solution added to the used oil will be in the range of 0.2 to 15% by weight over dehydrated used oil, depending on the degree of contamination that the used oil presents and the quality of the distillates We want to get. The more alkali we add to the used oil, the better the results on the distillates. c) Extraction of glycols and other hydrocarbons.

At this stage, glycols, light hydrocarbons, decomposition products of spent additives, and water incorporating the basic solution added in the pretreatment stage are separated from the used oil. For this an improved flash column is used,

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REPLACEMENT SHEET (RULE 26) similar to that used in the dehydration stage, but sized for the working conditions of this stage. The oil is aspirated by a pump from the bottom of the column, sends a portion of the oil to the next stage of the process, and the rest is sent to a heat exchanger. The oil is heated in the heat exchanger at a temperature around 200 ^e C, to prevent coking. Being the preferred temperature range between 190 and 220 ^e C. The oil that leaves the exchanger is mixed with the current that comes from the pretreatment through a static mixer. The mixed current passes into the improved flash column. The mixed stream entering the column contains between 3 and 12% by weight of the feed stream. The vapors produced in the column leave from the top of the column and go to a condenser, preferably surface, where they condense. The condensate obtained is a mixture of glycols, light hydrocarbons, decomposition products of additives and water residues. This mixture has a high calorific value and is used for energy recovery in large ovens. The column works with a vacuum in the range of 400 to 600 mbar. The incondensables are captured by the extraction and purification system, and sent to the boiler of the plant for incineration. This avoids odor emissions.

The advantage of incorporating this stage, before the extraction of spindle, is to obtain a spindle oil free of contaminants and suitable for use in the boilers of the plant without causing damage to burners and fouling in the home. d) Spindle oil extraction. In this stage, the main fuel that will supply the regeneration plant is extracted. For this, the improved flash column is used. The oil is aspirated by a pump from the bottom of the column, sends a portion of the oil to the next stage of the process, and the rest is sent to a heat exchanger. The oil is heated in the heat exchanger at a temperature below 275 ^e C to minimize cracking. Being the preferred temperature range between 250 and 275 ^e C. The oil leaving the exchanger is mixed with the current coming from the previous stage through a static mixer. The mixed current passes into the flash column. The mixed stream entering the column contains between 3 and 12% by weight of the feed stream. The produced vapors leave the top of the column and go to a

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REPLACEMENT SHEET (RULE 26) condenser, preferably surface, where they condense. The condensate obtained is a spindle oil suitable for use in the boilers of the regeneration plant without any treatment. The production of spindle oil covers the thermal needs of the plant, without resorting to external sources of supply. The column works with a vacuum in the range of 20 to 60 mbar. The incondensables are captured by the extraction and purification system, and sent to the boiler of the plant for incineration. This avoids odor emissions. e) Distillation of light and medium lubricant base.

In this stage the light and medium base oils are obtained by vacuum distillation, with average viscosities of 100 and 150 SUS respectively. For this, the improved flash column is used. The recirculation system sucks the oil from the bottom of the column, using a main pump, and sends it to a heat exchanger. A secondary pump, controlled by the column level control system, also aspirates from the bottom of the column and sends a portion of the oil to the next stage of the process. The oil is heated in the heat exchanger at a temperature below 345 ^e C to minimize cracking. Being the preferred temperature range between 290 and 305 ^e C. The oil leaving the exchanger is mixed with the current coming from the spindle extraction stage through a static mixer. The mixed current passes into the improved flash column. The mixed stream entering the column contains between 3 and 12% by weight of the feed stream. The vacuum inside the column is maintained in the range of 0.5 to 5 mbar. As explained above, during the operation of the process, a minimum volume of hot oil is maintained inside the column to maintain its temperature and avoid undesirable condensation. The produced vapors leave through the top of the column and go to a cyclone separator where the droplets of liquid separated are separated. The liquid collected in the cyclone separator, returns by gravity to the column. The vapors, once separated from any remaining liquid, pass through a first surface condenser where the average base oil condenses at a temperature between 230 and 280 ^e C. Using the condenser temperature control system we can obtain the viscosity desired, depending on customer requirements. Although any surface condensation system can be used, the preferred condensation system to minimize head loss is through an exchanger

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REPLACEMENT SHEET (RULE 26) of heat of the type of casing and tube, of a single passage through tubes, installed vertically and by passing the vapors through the interior of the tubes. The condensing medium oil falls by gravity from the condenser to a regulating tank, where a pump sucks it and sends it to a cooler for later storage. Vapors that do not condense are sent, through a cyclone separator, to a second condenser. In the cyclone separator the medium base oil trailers are collected, which fall by gravity to the regulating tank. This maximizes the performance of each distillation cut. The preferred installation of the second condenser is by means of a heat exchanger of the casing and tube type, with a single passage through tubes, installed vertically and by passing the vapors through the interior of the tubes. In this second condenser, it condenses the light base oil at a temperature between 150 and 190 ^e C. Vapors that do not condense in the second condenser are sent, through a cyclone separator, to the rubber collection system, prior to aspiration by the vacuum system. Due to the high heating temperatures of the oil in the distillation stages, cracks of the most unstable compounds of the oil and spent additives are produced. When these compounds condense, they polymerize to form a rubbery material that soils and breaks exchangers and vacuum equipment. To avoid these inconveniences, the process of the present invention works on the one hand with condensation temperatures of the distillation cuts, higher than the condensation temperatures of the cracked compounds, and on the other hand it incorporates a gummy material extraction system , prior to vacuuming of vacuum equipment. This system basically consists of a mixing condenser, a cooler, a recirculation system and a liquid level control system of the recirculation system. The non-condensed vapors in the first and second condenser are passed through a mixing condenser where a stream of spindle oil obtained in the process is recirculated. The recirculation system pump sucks from the bottom of the mixing condenser and sends the current, through a cooler, back to the liquid inlet of the mixing condenser. In this way, the gummy compounds are trapped and diluted in the spindle oil stream. The level control system acts on a regulating valve that draws a current equal to the amount of condensed compounds in the system from the recirculation system. The condensation temperature should be below 50 ^e C, preferably close to 40 ^e C. The current leaving the system, consisting of a mixture of spindle oil and condensed compounds, is sent to the fuel tank to its energy use in boilers.

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REPLACEMENT SHEET (RULE 26) By working this type of improved flash column in the distillation stages, without plates or fillings, higher voids are obtained and consequently the process works with significantly lower oil heating temperatures, of the order of 30 to 40 ^e C less than current processes This avoids on the one hand the cracking of the oil, increasing the performance of the process and on the other hand the fouling of the equipment by coking of the most unstable compounds. Additionally, the absence of refluxes and the liquid collection system, avoid on the one hand the continuous contamination of the clean vapors, and on the other the contamination of the condensates with dragging of the column's recirculation current. In this way, clear, bright and odorless distillates are obtained, which do not require any final treatment.

The versatility of the improved flash column also allows other distillation options such as: obtaining a single distillation cut with a single condenser or installing a rectification column at the outlet of the column vapors. f) Distillation of heavy lubricant base.

In this stage the heavy base oil is obtained by vacuum distillation, with an average viscosity of 300 SUS. For this, an improved flash column is used. The operation is the same as in the previous stage, with the only difference, that in this stage only the installation of a surface condenser is contemplated, since a single distillation cut is obtained. In this stage the recirculation current is heated in the heat exchanger at a temperature between 310 and 320 ^e C. The oil leaving the exchanger is mixed with the current coming from the previous distillation stage through a static mixer . The mixed current passes into the improved flash column. The mixed stream entering the column contains between 3 and 12% by weight of the feed stream. The vacuum inside the column remains in the range of 0.5 to 5 mbar. The vapors, once separated from any other liquid, pass through the surface condenser where it condenses at a temperature between 230 and 280 ^e C. This stage, like the previous one, has a rubber collection system prior to the system of emptiness. The distillation bottoms that leave the recirculation system continuously, are preferably removed therefrom by a pump independent of the recirculation pump, which is controlled by the level control system of the

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REPLACEMENT SHEET (RULE 26) column. Distillation funds are basically composed of heavy metals, salts from the reactions of pollutants with alkali, sediments, carbon particles and traces of heavy oil additives. Studies carried out by The Asphalt Institute and the US Department of Energy on the use of distillation funds (obtained in oil regeneration processes) on paving asphalts, conclude that the addition of funds to asphalts improves susceptibility to temperature and water resistance thereof. This by-product, similar to an asphaltic bitumen, is marketed as an asphalt modifier for the manufacture of asphalt sheets. The properties of this byproduct make it suitable for this use without any risk of leaching.

The characteristic difference of the process of the invention with respect to the prior art is the suppression of the final treatment thanks to the use of the improved flash column throughout the process and, especially, in the final stages of distillation of the bases. The novel design of the distillation column without reflux, allows working with high voids, up to 0.5 mbar, and consequently with heating temperatures of the product to be distilled significantly lower than the current distillation equipment. Because this type of column has no elements inside such as plates, fillings or reflux cones, both its manufacturing cost and its maintenance cost is much lower than the current equipment used in the sector. Additionally, the absence of reflux systems and contact elements inside the column allows the used oil to be pretreated with a basic solution in sufficient quantity to obtain distilled base oils that do not require final treatment.

With regard to the improved flash column itself, object of the invention, we can consider that the closest prior art is the unconventional column described in US 4140212. This column manages to evaporate instantaneously of the order of 90% of product thanks to a cyclonic inlet nozzle aided by various internal structures that, however, are subject to strong fouling. In the column of the invention the abrupt expansion of the inlet nozzle is replaced by a descending cyclonic prechamber whose section increases progressively, maintaining the rate of instantaneous evaporation thanks to a vacuum intensification, which is possible thanks to the minimum loss of load that is in the flash column, since it has no elements inside such as fillings or plates. Conventional distillation columns carry inside packages or plates that

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REPLACEMENT SHEET (RULE 26) they produce a considerable loss of load, having to work with a medium vacuum and, consequently, with higher heating temperatures. The addition of an external cyclone separator without reflux, at the outlet, and the use when necessary of a small impact separator, easily removable for cleaning, allow the suppression of the usual final treatment in the prior art.

The advantages of the process described are considerable. Thus, the process is easily automatable, requiring only one operator in the control room for its operation. Another added advantage of this process is the minimum time it takes to start and stop, which is in both cases below two hours. Additionally, in case of a possible breakdown in any of the stages, the process remains in stand-by mode until its solution. In this mode, the control system closes the inputs and outputs of the stages, blocks the heat input and keeps the recirculation systems running. The versatility of the process also allows, if necessary, to bypass the faulty stage, and continue working with the rest of the stages until the fault is resolved. The process cleaning operation is simple and quick, normally a few hours are required to complete the cleaning of the equipment. This operation consists of filling the used oil circuit, with a water-based cleaning liquid, and recirculating through the recirculation systems of each of the stages, for two or three hours at a temperature around 55 ^e C. Once the time has elapsed, the circuits are emptied by the process pumps themselves.

Brief description of the figures To complement the foregoing description, and in order to help a better understanding of the features of the invention, a detailed description of a preferred embodiment will be made, based on a set of drawings that accompany This descriptive report and where, for guidance and non-limiting purposes, the following has been represented.

Figure 1 shows the flow chart of the used oil regeneration process of the invention.

Figure 2 shows a schematic representation of the dehydration stage of the

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REPLACEMENT SHEET (RULE 26) used oil regeneration process of the invention.

Figure 3 shows a schematic representation of the chemical pretreatment step of the used oil regeneration process of the invention.

Figure 4 shows the extraction of glycols and other hydrocarbons from the used oil regeneration process of the invention.

Figure 5 shows a schematic representation of the spindle oil extraction stage of the used oil regeneration process of the invention.

Figure 6 shows a schematic representation of the first part of the light and medium lubricating base distillation stage of the used oil regeneration process of the invention.

Figure 7 shows a schematic representation of the second part of the light and medium lubricating base distillation stage of the used oil regeneration process of the invention. Figure 8 shows a schematic representation of the first part of the heavy lubricant base distillation stage of the used oil regeneration process of the invention.

Figure 9 shows a schematic representation of the second part of the heavy lubricant base distillation stage of the used oil regeneration process of the invention.

Figure 10 shows an elevation view of the improved flash column of the invention. Figure 1 1 shows a horizontal section along the line A A 'of the improved flash column of the invention.

Figure 12 shows a plan view of the improved flash column of the invention.

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REPLACEMENT SHEET (RULE 26) Figure 13 shows a middle vertical section of the improved flash column of the invention and the external centrifugal separator.

Figure 14 shows a plan view of the external centrifugal separator coupled to the improved flash column of the invention.

Detailed description of a preferred embodiment.

In the particular case to be described the process of the invention comprises several steps, as shown in the general flow chart of Figure 1. a) Dehydration, b) Chemical pretreatment, c) Extraction of glycols and other hydrocarbons, d) Extraction of spindle oil, e) Distillation of light and medium base, in an improved flash column (1) according to claims 1 and 2 , at a pressure of 0.5 to 5 mbar and a temperature between 290 and 305 ^< Ό. f) Heavy base distillation, on an improved flash column (1) according to claims 1 and 2, at a pressure of 0.5 to 5 mbar and a temperature between 310 and 320 ° C.

The procedure begins with stage a) dehydration (section 100), as shown in Figure 2, in which the feed oil, once decanted and filtered, enters the process by means of the pump P101, the which injects it to the static mixer M101 through: the heat recovery E201, where it is preheated by absorbing heat from the output current of the EFC101 column, and the flow control system composed of the FT101 flowmeter, a flow controller and the CV101 control valve. In the static mixer M101, the feed current is mixed with the recirculation current of the column EFC101. Oil from the recirculation stream is aspirated

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REPLACEMENT SHEET (RULE 26) by pump P102 from the bottom of column EFC101, and sent back to column EFC101 through, first of heat exchanger E101 A or B, where it is heated to a temperature between 140 and 150 ^e C, and after M101 static mixer. The current thus mixed passes into the column EFC101, which is maintained at atmospheric pressure. Water and light hydrocarbons are separated from oil in column EFC101. The produced vapors leave through the top of the column and go to the E102 condenser where they condense. The condensate obtained is sent by gravity, to avoid emulsions, to a coalescing decanter where light hydrocarbons are separated from water. The water thus obtained can be recycled, with minimal treatment, for use in the plant's cooling systems. The level in column EFC101 is controlled by a level control system, which is composed of a level transmitter, a level controller and a CV101 control valve. The dehydrated oil leaving the CV101 control valve is sent to stage b) of chemical pretreatment (section 200), see figure 3, through an E201 heat recuperator, where it is cooled to a temperature between 80 and 90 ^e C. The cooled oil passes through the static mixer M201 where it is mixed with a 50% KOH solution. The mixed stream finally passes to the process reactor R201. To add the correct amount of potash, between 1% and 15% by weight of the used oil, a control system consisting of an FT201 oil flow meter, a FT202 KOH flowmeter, a frequency converter and a pump is available P202 dosing machine, which aspires from a V201 potash feed tank. In the R201 reactor, the dehydrated oil and the potash are mixed and reacted for one hour. Enough time to achieve a complete mixture and cause the desired reactions. With a proper sizing of the reactor volume a process is achieved in continuous mode. The P201 pump sucks the treated oil from the bottom of the reactor and sends it to the next stage. The R201 reactor has a level control system to prevent overfilling and emptying thereof.

The scheme of step c) of extracting glycols and other hydrocarbons (section 300) is shown in Figure 4. The pretreated oil leaving the reactor R201 is sent, by means of the pump P201 to the static mixer M301 of section 300. In the static mixer M301 the current leaving the reactor is mixed with the recirculation current of the column EFC301. The oil from the recirculation stream, is sucked by the pump P301 from the bottom of the column EFC301, and sent back to the column EFC301 first through the heat exchanger E301 A or B, where it is heated to a temperature

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REPLACEMENT SHEET (RULE 26) between 190 and 220 ^e C, and after the static mixer M301. The current thus mixed passes into the column EFC301, which is maintained with a vacuum between 400 and 600 mbar. The vapors produced in the column leave from the top of the column and go to a condenser where they condense. The condensate obtained is a mixture of glycols, light hydrocarbons, decomposition products of additives and water residues. This mixture has a high calorific value and is used for energy recovery in large ovens. The level in column EFC301 is controlled by a level control system, which is composed of a level transmitter, a level controller and a CV301 control valve. Oil leaving the CV301 control valve is sent to stage d) of spindle extraction (section 400) Figure 5. The operation of the spindle extraction stage is similar to the previous stage. Only the heating temperature and the vacuum in the column change. In this case, the recirculation current of column EFC401 is heated in exchanger E401 A or B at a temperature between 250 and 275 ^e C, and the vacuum in column EFC401 is maintained between 20 to 60 mbar. The vapors produced leave the top of the column and go to a condenser, preferably surface, where they condense. The condensate obtained is a spindle oil suitable for use in the boilers of the plant. Oil leaving the CV401 control valve is sent to the distillation stage of the light and medium base. All evaporation / distillation modules include the installation of two heating exchangers to allow cleaning of one while the other is in operation. To achieve the temperatures desired heating at different stages of the process, a heat transfer medium circuit is used with a maximum temperature between 340 ^and 350 ^and C. In the steps of dehydration, removal of glycols and extraction spindle, it is recommended to work with a temperature of thermal fluid lower than the maximum boiler outlet, through the implementation of a specific recirculation system for each stage. In this way, it is possible to work, for example, with thermal fluid temperatures around 200 ^e C in the dehydration stage, 260 ^e C in the glycol extraction stage and 315 ^e C in the spindle extraction stage. With this system of use of temperatures of progressive thermal fluid the fouling of the exchangers is prevented.

Figures 6 and 7 show step e) of distillation of the light and medium lubricant base (section 500). The oil from section 400 is mixed in the static mixer

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REPLACEMENT SHEET (RULE 26) M501, with the recirculation current of column EFC501, which has been previously heated in the exchanger E501 A or B, at a temperature between 290 and 305 ^e C. The mixed current enters column EFC501 where the cuts of vaporize desired distillation. The rest of the oil that does not vaporize falls to the bottom of the column where the recirculation pump P501 aspirates it and recirculates through the exchanger E501 A or B. A portion of the bottoms of the column EFC501 is aspirated by the pump P502 and sent to The next stage. The P502 pump is controlled by the EFC501 column level control system. The vacuum inside the column is maintained in the range of 0.5 to 5 mbar. The produced vapors leave through the top of the column and go to a cyclone separator V501 where the droplets of liquid are separated. The liquid collected in the cyclone separator returns by gravity to the EFC501 column. The vapors, once separated from any remaining liquid, pass through a first surface condenser E502 where the medium base oil condenses at a temperature between 230 and 280 ^e C. The condensing medium oil falls by gravity from the condenser to a reservoir of regulation V502, where the P503 pump sucks it and sends it to the E503 cooler for later storage and commercialization. Vapors that do not condense on exchanger E502 are sent, through a cyclone separator V503, to a second condenser E504. In the cyclone separator the medium base oil trailers are collected, which fall by gravity to the regulation tank V502. In the condenser E504, it condenses the light base oil at a temperature between 150 and 190 ^e C. The condensing light oil falls by gravity from the condenser to the regulation tank V504, where the P504 pump sucks it and sends it to the E505 cooler for later Storage and marketing. Vapors that do not condense on the E504 are sent, through a cyclone separator V505, to the E506 mixing condenser. In the V505 cyclone separator, the light base oil trailers are collected, which fall by gravity to the V504 regulating tank. The non-condensed vapors in the first and second condenser are passed countercurrently, in the E506 condenser, with a stream of spindle oil obtained in the process. The pump of the recirculation system P505, sucks from the bottom of the mixing condenser E506 and sends the current, through the cooler E507, back to the liquid inlet of the mixing condenser. In this way, the gummy compounds are trapped and diluted in the spindle oil stream. The level control system acts on the CV501 regulating valve that draws a current equal to the amount of condensed compounds in the system from the recirculation system. The condensation temperature should be below 50 ^e C, preferably close to 40 ^e C.

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REPLACEMENT SHEET (RULE 26) Current leaving the system, consisting of a mixture of spindle oil and condensed compounds, is sent to the fuel tank for energy use. Figures 8 and 9 show step f) of distillation of the heavy lubricant base (section 600). The oil from section 500 is mixed, in the static mixer M601, with the recirculation current of the column EFC601, which has been previously heated in the exchanger E601 A or B, at a temperature between 310 and 320 ^e C. The mixed stream enters column EFC601 where the desired distillation cuts are vaporized. The rest of the oil that does not vaporize falls to the bottom of the column where the recirculation pump P601 aspirates it and recirculates through the exchanger E601 A or B. A portion of the distillation bottoms of the column EFC601 is aspirated by the pump P602 and sent to the asphalt storage warehouse for later commercialization. The P602 pump is controlled by the EFC601 column level control system. The vacuum inside the column is maintained in the range of 0.5 to 5 mbar. The produced vapors leave through the top of the column and go to a V601 cyclone separator where the droplets of liquid are separated. The liquid collected in the cyclone separator, returns by gravity to the EFC601 column. The vapors, once separated from any other liquid, pass through the E602 surface condenser where the heavy base oil condenses at a temperature between 230 and 280 ^e C. The condensing heavy oil falls by gravity from the condenser to a regulating tank V602, where the P603 pump sucks it and sends it to the E603 cooler for later storage and commercialization. Vapors that do not condense in the E602 exchanger are sent, through a cyclone separator V603, to the E604 mixing condenser. In the V603 cyclone separator heavy base oil trailers are collected, which fall by gravity to the V602 regulating tank. The non-condensed vapors in the E602 condenser are passed countercurrently, in the E604 condenser, with a stream of spindle oil obtained in the process. The pump of the recirculation system P604, sucks from the bottom of the mixing condenser E604 and sends the current, through the cooler E605, back to the liquid inlet of the mixing condenser. In this way, the gummy compounds are trapped and diluted in the spindle oil stream. The level control system acts on the CV601 regulating valve that draws a current equal to the amount of condensed compounds in the system from the recirculation system. The condensation temperature should be below 50 ^e C, preferably close to 40 ^e C.

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REPLACEMENT SHEET (RULE 26) Current leaving the system, consisting of a mixture of spindle oil and condensed compounds, is sent to the fuel tank for energy use. Figures 10 to 12 show the improved flash column 1. The column consists of a vertical cylindrical body 2 with lateral supports 3 for its installation, and a bottom type klopper 4 or similar in the lower part, in which the outlet pipe of the bottoms of the column 5 are located in the center and a tubing for instrumentation 6. The column also has a flanged top cover 7 for inspection and cleaning of the interior impact separator 12. This cover has lugs 8 for easy assembly and disassembly. The product to be distilled enters through the tubing 9, and moves downwards towards the cyclonic evaporation chamber 10. In the chamber, the liquid moves through the bottom, which has a slope towards the bottom of the column to print the liquid a downward cyclonic movement. Steam is formed progressively inside the chamber while separating it from the liquid by the action of gravity and centrifugal force. When the mixture of liquid and incipient steam enters the column through the opening 1 1, the total evaporation of the product to be distilled occurs. The liquid that enters the column moves with a rotating downward movement towards the bottom of it and the steam, formed with the help of the high vacuum inside the column, rises towards the top. The rising vapors pass through the optional removable impact separator 12 for the separation of droplets and particles up to 10 μηι in diameter, and leave the column through the lateral upper tubing 13. In Figure 6 a sectional view of the column where the situation of the optional internal impact separator can be seen. As shown in Figures 13 and 14, the column can be coupled to an external cyclone 14 connected in the outlet pipe of the vapors by means of a flanged connection 15. Vapors leaving the column enter directly into cyclone 14, where the drops that the steam could drag are definitively separated. The dry vapors leave the cyclone towards the condensers through the pipe 16 which, advantageously, can have its flared bottom to reduce the drag, and the collected liquid leaves the cyclone through the lower pipe 17 to return to the column through the pipe 18 The cyclone 14 has a flanged top cover 19 for cleaning and inspection, which has elements for lifting 20 in assembly and disassembly. Cyclone 14 also has brackets 21 for installation. To avoid undesirable condensations and

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REPLACEMENT SHEET (RULE 26) maximizing the distillation performance, the column 1 and the external cyclone 14 have an insulating layer 22 of the rock wool type or the like, coated on the outside with a resistant material, aluminum sheet type or the like, to protect it. The column also has an extra volume 23 at the bottom thereof, to maintain a mass of hot bottom product in sufficient quantity to provide the necessary heat to the column that counteracts the cooling produced by the evaporation of the most volatile compounds, and to feed the recirculation system in the case of applications with used oils and heat sensitive products. Lateral tubing 24 is also available for instrumentation.

The flash column shown in Figures 13 and 14 corresponds to a hypothetical configuration that incorporates all the options of the invention. Table I indicates for the particular procedure described in the preferred embodiment, the configuration and operating conditions of the improved flash column corresponding to the different stages. The configuration indicates elements added on the cyclonic evaporation chamber (10), essential in any case.

TABLE I TEMPERATURE PRESSURE CONFIGURATION STAGE

Dehydration Atmospheric impact separator 140 - 150 ° C

Extraction of glycols Impact separator 400 - 600 mbar 190 - 220 ° C and other hydrocarbons

Spindle oil extraction Impact separator 20 - 60 mbar 250 - 275 ° C

Light base distillation Cyclonic output 0.5 - 5 mbar 290 - 305 ° C and a half

Heavy base distillation Cyclonic output 0.5 - 5 mbar 310 - 320 ° C

The cyclone exit separator (14) is only essential in the distillation stages of

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REPLACEMENT SHEET (RULE 26) bases, since the high vacuum with which it works produces unwanted particle drag and liquid droplets that the impact separator (12) does not eliminate at 100% due to their high speed, and that must be separated to avoid contamination of distillates.

The fundamental part of the procedure is the use of the new improved flash column in the distillation stages of the lubricant bases. In the stages of dehydration, glycol extraction and spindle oil extraction, another column or evaporator design capable of separating two liquid phases by evaporation / distillation could be used. But due to the constructive simplicity and the efficiency of the improved flash column, it is advantageous to use this design at these stages. The versatility of the improved flash column allows, with a single basic design and an additional configuration adapted, to evaporate water, distill solvents, distill spindle oil, distill lubricant bases or even crude oil. You just have to properly dimension the different elements and establish the pressures (vacuum) and working temperatures.

As for the impact separator (12), it is necessary in the stages prior to the stages of distillation of bases, since it avoids in a simple and effective way the trawls that occur therein. It is simpler and cheaper than placing an external cyclone separator at the exit of the column.

A series of variants and alternatives that, while maintaining the essentiality of the invention, allow adapting the embodiment to the design and available means of production will be apparent to the person skilled in the art.

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REPLACEMENT SHEET (RULE 26)

Claims

one . Enhanced flash column (1) for the distillation of used oils, oils and hydrocarbon mixtures, characterized by understanding; a vertical cylindrical body (2), which ends internally in a klopper type toric bottom (4) in which an outlet pipe (5) for the bottom product, an upper cover (7) for inspection tasks and cleaning, a lateral tubing (13), flanged at the top of the column (1), for the output of the vapors, a product inlet pipe (9) to the column (1), attached to a cyclonic prechamber of evaporation (10), descending, whose section increases progressively as the liquid travels along it, arranged at a sufficient distance over the klopper-like toric bottom (4) to configure an extra volume (23), an insulating layer ( 22) that covers the set.

2. Improved flash column (1) for the distillation of used oils, oils and hydrocarbon mixtures, according to claim 1, characterized in that it comprises, connected to the lateral tubing (13), an external cyclone (14), coated with an insulating layer (22), for the separation of the liquid droplets that could be carried by the steam, returning by gravity the liquid collected in the cyclone (14) to the column (1) below the cyclonic evaporation chamber (10) .

3. Improved flash column (1) for the distillation of used oils, oils and hydrocarbon mixtures, according to claim 2, characterized in that the external cyclone (14) incorporates a central tubing (16) for vapor output.

4. Improved flash column (1) for the distillation of used oils, oils and hydrocarbon mixtures, according to claim 1, characterized in that inside the column (1), and between the cyclonic evaporation chamber (10 ) and lateral tubing (13)

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REPLACEMENT SHEET (RULE 26) Output, a removable impact separator (12) is available, with zig-zag diverter plates.

5. Improved flash column (1) for the distillation of used oils, oils and hydrocarbon mixtures, according to the preceding claims, characterized in that the insulating layer (22) is made of rock wool, coated on the outside with sheet metal of aluminum.

6. Procedure to regenerate used mineral oil, characterized by comprising the following stages: a) Dehydration, b) Chemical pretreatment, c) Extraction of glycols and other hydrocarbons, d) Extraction of spindle oil, e) Light and medium base distillation, in an improved flash column (1) according to claims 1 and 2, at a pressure of 0.5 to 5 mbar and a temperature between 290 and

305 ^< Ό. f) Heavy base distillation, on an improved flash column (1) according to claims 1 and 2, at a pressure of 0.5 to 5 mbar and a temperature between 310 and 320 ° C.

7. Method for regenerating used mineral oil according to claim 6, wherein the heating of the feed stream of the improved flash column (1) is carried out by mixing with a recirculation stream, with more flow than the supply current, which is aspirated by a pump at the bottom of the column and heated in a heat exchanger with a high pass speed.

Method for regenerating used mineral oil, according to claim 6, characterized in that step a) of dehydration comprises evaporating water and light oil vapors in an improved flash column (1), in accordance with the

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REPLACEMENT SHEET (RULE 26) claims 1 and 4, at atmospheric pressure and a temperature between 140 and 150 ° C.

9. Process for regenerating used mineral oil, according to claim 6, characterized in that step b) of chemical pretreatment comprises adding an organic or inorganic base to the dehydrated used oil, in a proportion between 1% and 15% in weight of the oil used, and homogeneously mix the oil and the base in a container with stirring system at a temperature between 80 ^e C and 90 ^e C for a time between 30 and 90 minutes.

10. Process for regenerating used mineral oil according to claim 9, characterized in that the base used is a 50% potassium hydroxide solution.

Method for regenerating used mineral oil, according to claim 6, characterized in that step c) of extracting glycols and other hydrocarbons comprises evaporation in an improved flash column (1), according to claims 1 and 4, at a pressure between 400 and 600 mbar and a temperature between 190 and 220 ° C.

12. Method for regenerating used mineral oil, according to claim 6, characterized in that step d) of extraction of spindle oil comprises its evaporation in an improved flash column (1), according to claims 1 and 4, a a pressure between 20 and 60 mbar and at a temperature between 250 and 275 ° C.

13. Method for regenerating used mineral oil, according to claim 6, characterized in that the vapors distilled in steps e) and f) condense into at least one surface condenser.

14. Method for regenerating used mineral oil, according to claim 13, characterized in that the non-condensed vapors in the surface condensers are passed countercurrently in a mixing condenser with a low or medium molecular weight hydrocarbon stream .

15. Process for regenerating used mineral oil according to claim 14, characterized in that the low or medium molecular weight hydrocarbon used is the spindle oil obtained in step d) of the process.

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REPLACEMENT SHEET (RULE 26)