FR3085283A1 - PROCESS FOR DESORPTION OF A SOLID ADSORBENT AND ASSOCIATED DEVICE - Google Patents

Abstract

The invention is a method for desorbing a solid adsorbent medium capable of adsorbing organic compounds from an aqueous effluent, said method comprising the following steps: - a step of providing an adsorbent medium resulting from a method of adsorption at an adsorption temperature; - a step of supplying a desorption liquid; a step of bringing the desorption liquid into contact with the solid adsorbent medium, comprising a step of regulating a desorption temperature between a first temperature greater than or equal to the adsorption temperature and a second temperature below a temperature d boiling of said desorption liquid. The invention also relates to a device for desorbing a solid adsorbent medium. The invention also relates to a device for treating aqueous effluents containing organic compounds as well as a treatment method comprising such a desorption method. Finally, the invention relates to the use of a liquid at a desorption temperature above the adsorption temperature and below its boiling temperature.

Description

PROCESS FOR DESORPTION OF A SOLID ADSORBENT AND ASSOCIATED DEVICE

TECHNICAL FIELD OF THE INVENTION The invention lies in the field of the treatment of aqueous effluents, in particular from the exploration or production of oil and gas. Said aqueous effluents are contaminated with hydrocarbons and other organic materials. These contaminants can be in free form and / or emulsified in suspension and / or in dissolved form.

The removal of these contaminants is a process which generally comprises an adsorption step on an adsorbent medium, which must be regularly desorbed (or regenerated), in particular when it is saturated with contaminants.

The invention relates more specifically to a process for desorbing adsorbent media. The invention also relates to a device suitable for implementing the desorption method, as well as a device and a method for treating effluents comprising a first desorption step according to the desorption method.

STATE OF THE ART [0004] The aqueous effluents from oil and gas exploration or production are generally also called "production waters" (EP). More specifically, this is wastewater generated during the exploration and production phases, such as oil and gas wells.

There are several solutions for drilling and extracting hydrocarbons, depending on the depth of drilling to be carried out, according to the densities of the oils to be recovered and the extraction gases used.

Among the hydrocarbons extracted, there are oils soluble in water, typically hydrocarbons with short chains and / or with functions which make them soluble, such as functions of the alcohol or carboxylic acid type. These oils are also toxic and sometimes volatile. When extracting oil offshore, it also extracts a mixture of pore water and injection water. This mixture of water containing hydrocarbons and in particular these soluble oils constitutes the production water.

The production water is thus contaminated with hydrocarbons, more widely with organic matter, in free form in suspension and / or in dissolved form.

The production water must be treated before being discharged into the sea, in accordance with the regulations in force, which is explained in particular because of their high toxicity. Regulations set limits for the discharge of these soluble oils to seawater: for example, the directives of the OSPAR (Oslo-Paris) and the Norwegian Environment Agency are among the most ambitious.

At least three main families of organic compounds naturally present in the produced water have been identified as being able to present a risk for the environment: these are volatile organic compounds Benzene, Ethyl-Benzene, Toluene and Xylene (called BTEX in the remainder of this document), polycyclic aromatic hydrocarbons (referred to as PAHs in the remainder of the document) and phenols.

The most typical organic pollutants are listed in Table 1 below.

However, these are potentially not the only ones and the treatment of production water must be able to eliminate other families of compounds and / or other compounds potentially present in production water, for example naphthenic type carboxylic acids. or fatty acids.

We can generally speak of "contaminants", "organic pollutants" or "organic compounds", the terms used being considered synonymous throughout this description, and can be used interchangeably. one in place of the other.

In order to be able to remove the various contaminants in a broad spectrum, the adsorption processes on solid media (liquid / solid extraction) are particularly well suited. Solid adsorbent media are chosen for their ability to adsorb BTEX, PAHs, phenols or other compounds. Several types of media can be combined in order to have the widest possible absorption spectrum.

When a solid adsorbent is no longer able to adsorb enough organic compounds, a desorption step must be carried out.

A desorption fluid is generally used in the form of a gas or a liquid having the capacity to recover all or almost all of the organic compounds adsorbed on the surface of the solid adsorbent. This allows on the one hand to desaturate the adsorbent medium for reuse, and on the other hand to recover the adsorbed organic compounds, which can be advantageously revalued.

The desorption step is therefore very important in the process for the treatment of production water from oil and / or gas exploration.

The choice of desorption fluid or fluids and desorption method (s) is therefore essential to optimize the treatment process.

During desorption, several phenomena can be implemented: liquid / liquid extraction and / or vaporization of contaminants are the main ones. In addition to these two phenomena, peripheral stripping phenomena (stripping in English), or gas entrainment can take place. The vaporization phenomenon is a function of the temperature and the pressure of the desorption fluid while the liquid / liquid extraction is also a function of the chemical properties of the desorption fluid and of the contaminants to be desorbed, the aim being to break down the molecular interactions characteristics of the adsorption phenomenon and entraining the contaminants in the desorption fluid by vaporization or liquid / liquid extraction.

In addition, the desorption fluid itself must be able to be desorbed (regenerated). The desorption (regeneration) of the desorption fluid is done by separating the contaminants from the desorption fluid. The choice of desorption fluid must therefore take into consideration its capacity to be desorbed itself (regenerated).

Finally, in particular to be authorized on petroleum sites, the desorption fluid must not be toxic or dangerous.

Patent applications FR3004242, FR3004243 and FR3004244 relate to industrial water treatment methods, generally having a temperature above 55 ° C, containing organic pollutants in the form of suspended or insoluble matter and / or materials soluble. The disclosed methods include a microfiltration or ultrafiltration step on membranes leading to a filtrate and to a concentrate, a step of adsorption of the suspended matter contained in the filtrate, said adsorption step being carried out on at least an adsorbent resin chosen from the group consisting of cross-linked non-ionized polymer resins and microporous carbon resins.

The methods further include a desorption step, also called regeneration in the cited applications, of the adsorbent resin, produced by a desorption means, or regeneration means, chosen from the group consisting of water vapor, a solvent, a base and / or an acid.

In these three patent applications, the adsorption step is carried out using a resin chosen to adsorb the main organic pollutants such as BTEX, PAHs and phenols. Adsorption is carried out on:

- non-ionized and mesoporous crosslinked polymeric resins, having pore diameters of between 5 and 10 nm, and / or

- microporous carbon resins (or mesoporous, since a pore diameter value of 8 nm is indicated).

The resins are in the form of balls, the diameter of which is around one tenth of a millimeter. They are chosen according to the organic pollutant (s) that one wishes to eliminate. The resins are housed in at least one column, generally two, which makes it possible to manage an adsorption phase of the pollutants and a desorption phase of the resins in parallel, the desorption being necessary when the adsorbent resin is saturated with pollutants.

The desorption of the contaminants adsorbed on the resins is carried out using a desorption fluid which is chosen from:

- water vapor (120 - 200 ° C; 120 - 150 ° C);

- a solvent with a low boiling point: base, acid, alcohol;

- a combination of several fluids among these.

The desorption fluid is itself regenerated by applying one of the following methods, depending on the type of fluid:

- condensation of water vapor leading to a recoverable oily phase and an aqueous phase saturated with organic compounds (which must be treated again by adsorption to reuse the water);

- evaporation and condensation of the solvent leading to a condensed solvent phase which can be reused.

Desorption by steam however has several disadvantages.

On the one hand, the specific heat of water is relatively high (4.18 kJ / kg ° K) and the change from the liquid state to the vapor state is costly in energy since it results from the rupture of intermolecular bonds.

On the other hand, a compression of the water vapor is required to reach the vaporization temperature of the contaminants, in order to desorb them:

- 3.7 bar to reach 150 ° C and desorb BTEX;

- 14.5 bar to reach 200 ° C and desorb phenols with less than 3 carbon atoms;

- 22 bar to reach 220 ° C and desorb the Naphthaene;

- 85 bar to reach 300 ° C and desorb phenob and PAH with long chains (more than 3 carbon atoms).

In fact, when the desorption fluid is in the form of gas (in this case, in the form of water vapor), the predominant phenomenon of desorption of the contaminants is the vaporization of said contaminants. The liquid-liquid extraction phenomenon can be active to a lesser extent and only if part of the vapor condenses during desorption.

The desorption of the vapor media is therefore incomplete if the temperature is not sufficient to vaporize and therefore desorb all the contaminants, and in particular the long-chain phenols and PAHs which have a high boiling point as indicated in Table 1 below:

Contaminant groups Representative contaminants Boiling point (° C) BTEX Benzene 80.1 Toluene 110.6 Ethylbenzene 136 Xylene 140 PAH Naphthalenes Naphthalene 218 PAH with 2-3 benzene rings Phenanthrene 340 PAH with 4-6 benzene rings Chrysene Benzo (a) pyrene 448 495 Phenols Alkyl Phenols C0-C3 Phenol p-Cresol 181.7 201.8 Alkyl Phenol C4-C5 Pentylphenol 251 Alkyl Phenol C6-C9 Nonyl-phenol 293

Table 1: examples of the most typical organic pollutants If, on the contrary, a liquid solvent with a low boiling point (base, acid, alcohol) is chosen as the desorption fluid, it will cause health problems and / or due to its volatility and / or toxicity and / or flammability. In addition, it will generally be difficult to regenerate, due to the difficulty in separating contaminants from a low boiling liquid solvent.

It is also known to use propane as the desorption fluid, for example in patent application US2016243527 "Methods for regeneration of an organosilica media". However, desorption with propane is expensive because to desorb the media, it is necessary to liquefy the propane by lowering the temperature and / or compression. In addition, desorption with propane is dangerous because of its explosiveness and flammability.

The invention aims to overcome the aforementioned drawbacks of the prior art.

More particularly, it would be advantageous to provide a method for desorbing an adsorbent medium, as well as a device implementing such a desorption method, which minimizes energy consumption, and the desorption time, while by increasing the desorption yield.

In addition, it would be particularly advantageous to limit, or even avoid, the use of potentially dangerous and / or potentially toxic chemicals in a process for treating an aqueous effluent containing organic compounds.

STATEMENT OF THE INVENTION A first object of the invention making it possible to achieve at least one of the previously mentioned aims is a process for desorption of all or part of a solid adsorbent medium capable of adsorbing organic compounds of a aqueous effluent, said process comprising the following steps:

- a step of supplying a solid adsorbent medium resulting from an adsorption process, at an adsorption temperature;

- a step of supplying a desorption liquid;

a step of bringing the desorption liquid into contact with all or part of the solid adsorbent medium, said step of bringing into contact comprising a step of regulating a desorption temperature between a first temperature greater than or equal to the adsorption temperature and a second temperature below a boiling temperature of said desorption liquid.

Throughout the description, the term "adsorbent media" is defined as being a set of solid adsorbent particles, conditioned or not, and arranged in a container, for example a column of adsorbents or a bed of 'adsorbents.

According to a particular mode, the solid adsorbent medium is a microporous or mesoporous material.

By "microporous material" is meant in the sense of the present invention a porous material, whose average pore size is less than or equal to 2 nm.

By "mesoporous material" is meant in the sense of the present invention a porous material, the average size of the pores is between 2 and 50 nm.

The microporous or mesoporous material is typically chosen from a crosslinked polymeric material, preferably non-ionized, an organo-silica, an activated carbon, a carbonated resin.

An example of crosslinked polymeric material is a crosslinked polystyrene material or a styrene-divinylbenzene copolymer.

The term "organo-silica" denotes a compound containing silicon, oxygen and hydrocarbon substituents. Thus, typically, an organo-silica is represented by the formula RO-Si-OR, where R is a hydrocarbon substituent, the hydrocarbon chain of which can include substituents comprising heteroatoms, and / or whose carbon atom is replaced by a heteroatom, in particular. Thus, the hydrocarbon substituents can include heteroatoms such as nitrogen, sulfur, phosphorus, oxygen or a halogen. Within the meaning of the present invention, a hydrocarbon substituent means in particular a saturated, linear or branched alkyl or alkylene chain, comprising from 1 to 12 carbon atoms, preferably from 1 to 6 carbon atoms, and of which one carbon atom may be replaced by -O-, -S- or -N (alkyl Ci-C ₆₎ -. A hydrocarbon substituent can also comprise an aromatic ring of benzene or heteroaromatic type, in particular a pyridinyl or thiophenyl ring. An example of an organosilica is in particular the OSORB resin sold by PRO SEP.

Carbon resins are well known to those skilled in the art. A carbonaceous resin may for example be the resin known under the trade name Lewatit®AF5.

According to one embodiment, the solid adsorbent medium is a non-ionized material.

Throughout the description, the adsorption temperature is defined as being the temperature of the adsorbent medium and / or of the aqueous effluent in contact with said adsorption medium during an adsorption process. Throughout the description, the desorption temperature is defined as being the temperature of the desorption liquid when brought into contact with the adsorbent medium.

Those skilled in the art understand that the temperatures are defined relative to the operating pressure conditions.

The step of regulating the desorption temperature has the effect of keeping the desorption temperature lower than the boiling temperature of the desorption liquid, and preferably greater than or equal to the adsorption temperature (at + / - 10 ° C, or even at + / 5 ° C), and this, at least during the contacting of said desorption fluid with all or part of the adsorbent medium.

The step of regulating the desorption temperature may include determining the temperature of the desorption liquid.

In one embodiment, the determination of the temperature of the desorption liquid comprises at least one measurement of the temperature of said desorption fluid, for example at a pipe carrying said desorption liquid. The temperature can be measured for example using a thermocouple arranged in a pipe at the inlet of the adsorbent medium and / or at the outlet of said adsorbent medium.

In another embodiment, the determination of the temperature of the desorption liquid comprises at least one measurement of the temperature in contact with the container of the adsorbent medium, for example in contact with a column of media. The temperature can be measured for example using a thermocouple placed in contact with the container of the adsorbent medium, or even using an infrared thermometer.

In one embodiment, if the method identifies that the desorption temperature is greater than or equal to the boiling temperature of the desorption liquid, a cooling step can be triggered. The cooling can be done by recirculating at least a portion of the desorption liquid, for example in a condenser, or by an air sweep, the whole for a period of time is predetermined, or sufficient for the measured desorption temperature to return below the boiling point of the desorption liquid.

In one embodiment, if the method identifies that the desorption temperature is less than or equal to the adsorption temperature, a heating step can be triggered. The desorption liquid can be heated directly, for example by recirculation of at least part of the desorption liquid in a pipe and using a heat exchanger, or by recirculation of at least part of the desorption liquid in a tank and using a heating resistor, or indirectly by heating the adsorbent medium.

The method may include a step of determining the adsorption temperature.

The step of determining the adsorption temperature can comprise recovering said adsorption temperature in a database, in information transmitted with the adsorbent medium supplied by a supplier, or even a measurement of temperature during an adsorption phase when the desorption process is included in an aqueous effluent treatment process including an adsorption step followed by a desorption process according to the invention as described below.

Throughout this description, the terms "desorption" and "regeneration" mean the same thing, and either of the terms may be used interchangeably.

Desorption is defined as the reverse phenomenon of adsorption, whereby the adsorbed molecules detach from the adsorbent medium or are extracted from the desorption fluid. This allows on the one hand to reuse the adsorbent medium, and on the other hand to recover the adsorbed organic compounds, which can be advantageously upgraded. This also allows reuse of the desorption fluid.

In addition, the terms "upstream" and "downstream" are defined relative to the direction of flow of the aqueous effluent in the process.

Within the meaning of the present invention, an organic pollutant is understood to mean a compound comprising at least one C-H bond (carbon-hydrogen).

In the present invention, organic pollutants include or consist essentially of volatile organic compounds of the BTEX family, polycyclic aromatic hydrocarbons (PAH), phenols, naphthenic carboxylic acids and fatty acids.

Examples of BTEX are benzene, toluene, ethylbenzene and xylene.

Examples of PAHs are compounds comprising 2 to 6 joined aromatic rings, optionally substituted with 1 to 4 C1-C4 alkyl chains. In particular it can be:

- a naphthalene, optionally substituted with 1 to 4 C1-C4 alkyl chains,

- a phenanthrene, optionally substituted with 1 to 4 C1-C4 alkyl chains,

- a benzo (a) pyrene,

- a chrysene, optionally substituted with 1 to 4 C ₁ -C ₄ alkyl chains.

Examples of phenols are compounds of formula R-PhOH, where Ph represents a benzene ring, R represents a hydrogen atom or a C1-C10 alkyl chain, in particular a C1-C9 alkyl chain. For example, R represents H, CH ₃ , CH ₃ (CH ₂ ) ₄ or CH ₃ (CH ₂ ) 8 · The substituents R and OH can take any possible relative positions. Thus, the substituent R can be found in ortho, in meta or in para with respect to the substituent OH. Examples of phenols according to the invention are: phenol, cresol (in particular p-cresol), pentylphenol and nonylphenol.

A naphthenic carboxylic acid is typically a compound of formula R-Ar-COOH, in which Ar represents a naphthenic nucleus and R represents a hydrogen atom or a C1-C10 alkyl chain, in particular a C1-alkyl chain C9. For example R represents H or CH ₃ . A fatty acid is typically a carboxylic acid with a C ₄ -C ₃₆ aliphatic chain, in particular from C ₈ to C ₂₈ . In general, the alkyl chain comprises an even number of carbon. An aliphatic chain is an alkyl or alkene chain.

Within the meaning of the present invention, an alkyl is a saturated, linear or branched monovalent hydrocarbon chain. By way of example of a C ₁ -C ₆ alkyl chain, mention may be made of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl or even hexyl groups.

Within the meaning of the present invention, an alkene is a monovalent unsaturated, linear or branched hydrocarbon chain, comprising as unsaturation only double bonds (no triple bonds). Double bonds can be cis or trans.

The most typical organic pollutants are listed in Table 1.

The method according to the invention uses a fluid which is in the liquid state during desorption, while being at a temperature above the adsorption temperature.

On the one hand, the fact that it is a liquid at a temperature above the adsorption temperature makes it possible to optimize the desorption. This is because heat weakens the adsorption bonds and increases the efficiency of desorption.

On the other hand, the fact that the fluid remains in a liquid state makes it possible to reduce energy consumption. It takes less energy to heat a liquid without changing its state, that is to say without the liquid vaporizing.

In addition, when the desorption fluid remains in liquid form during the desorption process, while being at a temperature capable of vaporizing the contaminants, the desorption is done by a double mechanism of vaporization and liquid-liquid extraction. . This double mechanism increases the regeneration capacity of the media. The liquid-liquid extraction mechanism is paramount.

Energy consumption is all the more optimized since the desorption liquid has a low specific heat, for example lower than that of water.

According to one embodiment, the desorption liquid has a boiling temperature greater than or equal to 80 ° C, which is the temperature necessary to break the adsorption bonds established between the adsorbed molecules and the media. adsorption used.

According to one embodiment, the desorption liquid is water.

According to one embodiment, the desorption liquid comprises an organic solvent, preferably polar, optionally in admixture with water. Typically, the desorption liquid is chosen from alcohols and / or compounds of the glycol family, optionally in admixture with water.

For the purposes of the present invention, the “alcohols” are understood to mean compounds of formula R'-OH, in which R 'represents a saturated, linear or branched hydrocarbon chain, comprising from 3 to 12 carbon atoms, preferably 3 to 4 carbon atoms. Examples of alcohols are in particular propanol and in particular isopropanol, nbutanol and tert-butanol (or t-butanol).

It is preferably a compound of the glycol family such as a Mono Ethylene Glycol (MEG) or / and a Tri Ethylene Glycol (TEG).

Within the meaning of the present invention, a compound of the glycol family is a compound of formula HO- (CHR _an -CHR _bn -O) _n -H, in which:

n is an integer between 1 and 10, in particular between 1 and 4, preferably between 1 and 3,

- R _an and R _bn independently represents a hydrogen atom or a CH ₃ group, provided however that, for each n, if R _an represents CH ₃ , then R _bn represents H, and if R _bn represents CH ₃ , then R _an represents H.

Preferably, R _an and R _bn both represent a hydrogen atom, and n typically represents 1,2 or 3.

The advantage of a polar solvent is that it avoids being adsorbed by the adsorbent medium.

According to a particular embodiment, the desorption liquid comprises Mono Ethylene Glycol (MEG).

According to a particular embodiment, the desorption liquid comprises Tri Ethylene Glycol (TEG).

The Applicant has established that the heated MEG or the heated TEG is a desorption liquid clearly more effective than another liquid, for example a solvent with low boiling point, which is more such an unheated solvent .

The Applicant has discovered that MEG as a heated desorption fluid has a desorption capacity much higher than that of the known compounds.

In addition, it is particularly advantageous to use MEG or TEG as a desorption liquid on a gas field where MEG and / or TEG are generally used to dehydrate a gas, it is therefore a resource generally available, and thus means exist in situ to regenerate said desorption liquid.

Finally, the MEG and the TEG have high boiling temperatures, which makes it possible to heat the desorption liquid, and thus to optimize the desorption without, however, vaporizing said liquid.

According to one embodiment, the desorption liquid is supplied at a temperature below the desired desorption temperature. In this case, said desorption liquid is heated later in the step of supplying said liquid.

According to one embodiment, the desorption liquid is heated prior to the step of bringing it into contact with the adsorbent medium.

According to a particular embodiment, the desorption liquid is heated at the level of a pipe upstream of the adsorbent medium, for example using a heat exchanger. According to another particular embodiment, the desorption liquid is heated at the level of a storage tank for said liquid disposed upstream of the adsorbent medium, for example using a heating resistor.

According to an alternative or complementary embodiment, the desorption liquid is heated during the step of bringing said desorption liquid into contact with the adsorbent medium. According to this embodiment, the method comprises a step of heating the adsorbent medium, so as to bring said adsorbent medium to a temperature which allows the desorption liquid to reach the desired desorption temperature. Thus, the desorption liquid is heated during the step of bringing said desorption liquid into contact with said adsorbent medium.

The heating step of the adsorbent medium can be carried out before the contacting step or during the contacting step, or before and during the contacting step.

It is indeed advantageous to heat the adsorbent medium, itself heating the desorption liquid when brought into contact. This improves energy efficiency, and that of desorption.

According to a particular embodiment, the adsorbent medium is heated to a temperature greater than or equal to 80 ° C, preferably between 100 and 190 ° C.

According to a particular embodiment, the adsorbent medium is heated before bringing the desorption liquid into contact with said adsorbent medium.

According to another particular embodiment, the adsorbent medium is heated during the contacting of the desorption liquid with said adsorbent medium.

According to a particular embodiment, the adsorbent medium is heated before bringing the desorption liquid into contact with said adsorbent medium, and during the bringing of the desorption liquid into contact with said adsorbent medium.

According to an advantageous embodiment, the adsorbent medium is heated by injecting water vapor onto said adsorbent medium. The injection of water vapor onto the adsorbent medium has a very significant impact on the desorption capacity of the medium by the desorption liquid. Said desorption liquid is brought into contact with the media after the injection of water vapor.

The injection of water vapor preferably lasts less than or equal to 5 minutes.

Advantageously, the injected water vapor has a temperature between 100 and 140 ° C, preferably between 120 and 140 ° C, for example equal to 120 ° C. This allows most of the major contaminants that are BTEX to be infected.

According to an alternative or complementary embodiment, the adsorbent medium is heated by resistance or by a heating blanket.

According to an alternative or complementary embodiment, the desorption liquid is supplied, during the step of supplying said liquid, at the desired desorption temperature, or at a temperature approaching said desorption temperature.

The above embodiments can be combined with one another. In other words, a desorption liquid supplied at or near the desorption temperature can be reheated later in the supply step of said liquid. Likewise, the desorption liquid can be heated before the step of contacting with the desorption medium, and also heated during the contacting with the desorption medium.

According to one embodiment which can be applied to all of the preceding embodiments, the desorption liquid is at a temperature greater than or equal to 80 ° C., which is the temperature necessary to break the connections of adsorption established between the adsorbed molecules and the adsorption media used, and preferably between 100 and 190 ° C to improve the desorption without consuming too much energy.

A second object of the invention is a method of treating aqueous effluents containing organic compounds, said method of treatment comprising the following steps:

- a step of adsorption of organic compounds from the aqueous effluent on a solid adsorbent medium;

- a first desorption step comprising the desorption process according to the first subject of the invention.

According to one embodiment, the treatment method further comprises:

- a step of determining a saturation level of the solid adsorbent medium, comprising:

• a step of measuring a parameter of the aqueous effluent consecutive to the adsorption step, and • a step of comparing the measured parameter with a predetermined threshold value making it possible to determine whether the level of saturation of the solid adsorbent medium is reached or exceeded;

a step for triggering the first desorption step when the saturation level of the solid adsorbent medium is reached or exceeded.

According to the invention, the term “saturation level of the adsorbent medium” means a saturation level of the adsorbent medium as defined by the operator, which is not necessarily 100% saturation of the adsorbent medium, but which is more generally a partial saturation of said adsorbent medium (the medium can still adsorb but it is less efficient). In other words, the first desorption step is preferably initiated before the adsorbent medium is completely saturated.

According to one embodiment, the measured parameter is the content of Total Organic Carbon (TOC) and / or the content of oils in the effluent (Oil in Water).

In this case, the measurement can be done using online analyzers which can be chosen from:

- an online Total Organic Carbon (TOC) analyzer, and / or

- an online analyzer of the oil content in the effluent (Oil in Water), for example a focused ultrasonic acoustic sensor, a chemical fiber optic sensor, an image analyzer, a turbidity sensor using the diffusion of the light, a photoacoustic sensor, a UV fluorescence sensor including laser induced fluorescence (LIF).

The threshold value used to determine whether the saturation level of the solid adsorbent medium is reached can be calculated starting from a contaminant leakage threshold measured in the treated water. This can correspond to a value between 10 and 100% of the “COT” or “Oil in Water” equivalent of the limit value for treatment or discharge of one or more specific contaminants (typically Phenols and / or BTEX and / or PAH) or the sum of the contaminants.

These leakage rates can take into account the examples of limit values for discharge into the sea offshore as presented in table 2 below:

Unit Example 1 Example 2 Benzene mg / l 1 0.5 Ethylbenzene mg / l 0.005 Toluene mg / l 0.18 Xylene mg / l 0.075-0.2 Total BTEX mg / l 1 Phenols mg / l 0.5 0.5 PAH mg / l 0.0004-0.07

Table 2: Examples of Thresholds for Discharge of Contaminants into the Sea According to one embodiment, the treatment method further comprises a step of reusing all or part of the solid adsorbent medium subsequent to the first desorption step.

According to one embodiment, the treatment method further comprises a step of rinsing the desorbed adsorbent medium, prior to the step of reusing said solid adsorbent medium.

This rinsing step can be preceded by a step of emptying the container of the adsorbent medium after the desorption process, for example emptying a column if the container is a column.

One and / or the other of the two preceding steps makes it possible to remove as many traces of pollutants as possible from the adsorbent medium.

According to one embodiment, the treatment method comprises a second step of desorption of at least part of the desorption liquid, subsequent to the first step of desorption of the adsorbent medium.

This allows to reuse at least part of the desorption liquid and therefore in particular to avoid overconsumption, to generate less waste, and to recover the desorbed organic compounds so as to recover them.

According to one embodiment, the second desorption step is carried out by a process capable of heating the desorption liquid in order to separate it from the contaminating organic compounds.

The second desorption step is preferably carried out by one of the following methods, capable of heating the desorption liquid in order to separate it from the contaminating organic compounds, or a combination of these methods:

- a fractional distillation stage: preferred solution if the boiling temperature of the liquid is lower than the boiling temperature of the contaminants;

- an evaporation step followed by a solvent condensation step: one of the solutions advantageously selected if the boiling temperature of the liquid is higher than the boiling temperature of the contaminants;

- a stripping step with steam or gas in a packed column or with trays or in a membrane contactor: one of the solutions advantageously selected if the boiling temperature of the liquid is higher than the boiling temperature of contaminants.

A third object of the invention is a device for desorbing a solid adsorbent medium, said device comprising:

- means for determining an adsorption temperature of an adsorption process from which the solid adsorbent medium is derived;

- means of supplying a desorption liquid;

means for bringing the desorption liquid into contact with all or part of the adsorbent medium; said desorption liquid being at a desorption temperature;

means for regulating the desorption temperature, preferably between a first temperature greater than or equal to the adsorption temperature and a second temperature below a boiling temperature of said desorption liquid.

According to one embodiment, the device comprises means for heating the desorption liquid.

According to one embodiment, the heating means comprise first heating means able to heat the desorption liquid before bringing said liquid into contact with the adsorbent medium. According to a particular embodiment, the first heating means comprise a heat exchanger, or a heating resistor.

According to another embodiment, the heating means comprise second heating means able to heat the adsorbent medium. According to a particular embodiment, the second heating means comprise a resistor and / or a heating blanket capable of heating the adsorbent medium.

According to a particular embodiment, the second heating means comprise means for injecting water vapor onto said adsorbent medium.

According to one embodiment, contacting means comprise at least one adsorbent column capable of containing the adsorbent medium, and preferably at least two adsorbent columns so as to keep at least one column in adsorption when the other is in desorption.

According to one embodiment, the device further comprises means for evacuating the solid adsorbent medium, for example a vacuum pump. Indeed, under vacuum, the desorption phenomenon is improved.

A fourth object of the invention is a device for treating aqueous effluents, comprising:

- adsorption means comprising at least one solid adsorbent medium;

- Means for measuring at least one parameter of the aqueous effluent leaving the adsorption means in the solid adsorbent medium;

- a device for desorbing said solid adsorbent medium according to the third subject of the invention.

The measurement means can be chosen from: an online Total Organic Carbon (TOC) analyzer, an online oil in effluent analyzer, for example: an ultrasonic acoustic analyzer, a chemical fiber optic sensor , an image analyzer, a turbidimeter, a photoacoustic sensor, a UV fluorescence analyzer including laser induced fluorescence.

A fifth object of the invention is the use of a liquid for desorbing a solid adsorbent medium containing organic contaminants resulting from a process for the adsorption of an aqueous effluent at an adsorption temperature, said liquid being at a desorption temperature above the adsorption temperature and below its boiling temperature.

The adsorbent media can be an adsorbent media as described above in connection with the desorption process and the desorption device of the invention.

Furthermore, the liquid is preferably a desorption liquid as described above.

Preferably, the liquid used is an MEG or a TEG.

Preferably, the adsorbent media is typically activated carbon.

DESCRIPTION OF THE FIGURES [0136] Other characteristics and advantages of the invention will become apparent with the aid of the description which follows, given by way of illustration and not limitation, made with reference to the appended figures among which:

- Figure 1 illustrates a desorption process according to the first object of the invention;

- Figure 2 illustrates MEG desorption tests of an adsorbent medium;

- Figure 3 illustrates an embodiment of the effluent treatment method according to the second object of the invention;

- Figure 4 illustrates a variant of the effluent treatment method of the embodiment of Figure 3.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS FIG. 1 illustrates a process for the desorption of a solid adsorbent medium capable of adsorbing organic compounds from an aqueous effluent, said process comprising the following steps:

- a step 10 of supplying the adsorbent medium (referenced "ADS1" in the figures) resulting from an adsorption process at an adsorption temperature;

- a step 20 of supplying a desorption liquid (referenced "LIQ1" in the figures);

a step 30 of bringing the LIQ1 desorption liquid into contact with all or part of the solid adsorbent medium ADS1, said contacting step comprising a step 40 of regulating a desorption temperature between a first temperature greater than or equal to the adsorption temperature and a second temperature below a boiling temperature of said desorption liquid.

At the end of the contacting step, a desorbed adsorbent medium, referenced "ADS2" in the figures, is obtained.

Desorption tests carried out with MEG as desorption liquid will be described, in relation to FIG. 2.

For all of these tests, the effluent to be treated has the same composition given in Table 3 below.

Compounds Concentration (ppm) BTEX Benzene 450 Ethylbenzene 11 Phenols Phenol 46.7 p-cresol 71.1 Penthylphenol 3.2 Nonylphenol 0.1 PAH Naphthalene 32.8 Phenanthrene 3.7 Chrysene ^<1> 0.001 Benzo (a) pyrenne 0.002 Glycols MEG 100 Salts NaCI 20,000

Table 3: composition of the effluent before treatment [0141] FIG. 2 illustrates the results of desorption tests with MonoEthylene Glycol (MEG) of an adsorbent medium, with or without injection of water vapor on said medium. The graph illustrated shows the TOC (Total Organic Carbon) value in the treated effluent as a function of the volume of aqueous effluent treated by passing over the adsorbent medium during 4 adsorption cycles.

Desorption between two adsorption cycles is triggered when the TOC concentration in the treated effluent exceeds the threshold of 55 mg / l. It can be seen that:

- MEG desorption after injection of steam at 120 ° C into the adsorbent medium allows recovery of 88% of the initial adsorption capacity of said medium;

- without steam injection at 120 ° C (and with MEG at room temperature), the initial adsorption capacity of the adsorbent medium is not restored.

The steam injection takes place for a duration preferably less than or equal to 5 minutes.

Another test (last row of table 4 below) showed that the MEG desorption heated to a temperature of 120 ° C., without injection of water vapor, allows recovery greater than 60% of the capacity d initial adsorption of the adsorbent medium. Table 4 also compares the results with water vapor desorption.

Table 4 groups together the results of the MEG desorptions:

Desorption fluid Restoration of the initial adsorption capacity (%) MEG at room temperature (20-25 ° C) after injection of water vapor (100-120 ° C) 88% MEG at room temperature (20-25 ° C) without prior steam injection 0% MEG heated to a temperature of 120 ° C > 60% Steam at 130 ° C 52%

Table 4: Results of the MEG desorptions [0147] It can be seen that:

- Desorption with heated MEG and MEG after injection of water vapor is more efficient than desorption with water vapor.

- The results of desorption with MEG heated to 120 ° C are better than those with steam, but a little less good than those of desorption with MEG at room temperature after injection of steam at 120-130 ° C. That said, the MEG desorption test heated to 120 ° C was conducted by statically contacting the heated MEG with the media bed, without MEG circulation. In dynamics, or even by increasing the temperature of the MEG to 150 ° C, the percentage of restoring of the initial adsorption capacity can be increased.

Mono-Ethylene Glycol (MEG) is particularly interesting, especially with respect to water. In fact, the energy required to heat the MEG is lower than to heat the liquid water. Indeed, to raise the temperature by one degree of one kg of water it takes 4.18 KJ (specific heat) while to raise the temperature by one degree of one kg of MEG, it takes 2.21 KJ, so half of energy.

Alternatively to MEG, it is possible to use, for example, Tri Ethylene Glycol (TEG).

Other desorption liquids can be used such as:

- Water

- (Iso) Propanol

- N-butanol

- T-butanol

- Other glycols than MEG or TEG, for example glycol ethers, and typically propylene glycol ...

The desorption process can be implemented independently of an effluent treatment process by adsorption. It can for example be implemented on a saturated adsorbent medium provided.

It can alternatively be integrated into a process for the treatment of effluents by adsorption. Thus, Figure 3 illustrates a method of treating an aqueous effluent (referenced "EP" in the figures for "production water") containing organic compounds. The process includes the following steps:

- A step 101 of adsorption of organic compounds comprising a step of bringing the aqueous effluent into contact with a solid adsorbent medium;

a step 102 for determining a saturation level of the solid adsorbent medium (optional step);

- A first step 103 of desorption of all or part of the solid adsorbent medium, comprising the desorption process.

At the end of the adsorption steps, a treated aqueous effluent is obtained, referenced "AND" in the figures.

The treated aqueous effluent can be discharged into the sea if it is produced water (possibly with analyzes to verify if it is compliant for the discharge and / or downstream treatments).

The adsorption step 101 is carried out by liquid / solid extraction on a solid adsorbent medium. The adsorbent medium comprises particles of solid elements chosen for their ability to adsorb compounds, in particular apolar, such as hydrocarbons, and in particular BTEX, PAH and Phenols.

The device implementing the adsorption comprises at least one unit containing solid adsorbents. Preferably, it contains two units, a first unit which can operate in adsorption, while a second unit works in desorption, and vice versa.

[0157] A unit can be a column filled with adsorbents. The flow of effluent to be treated in the columns is either ascending or descending.

The solid adsorbent medium used is formulated to allow the adsorption of organic compounds on its surface and / or within its pores.

The solid adsorbent medium is preferably in the form of microporous or mesoporous beads.

The solid adsorbent medium is preferably made of a non-ionized material.

The media can comprise a solid mesoporous or microporous adsorbent material, such as a polymeric material, an organosilica, a carbon resin or activated carbon. Typically, it is a carbonaceous material with a porous structure in the form of mesoporous beads, for example having diameters varying between 0.25 to 1 mm and a porosity ranging from a few nanometers to a few tens of nanometers (between 2 and 50 nm) (for example mesoporous activated carbon).

By way of example, the adsorbents which can be used are indicated in table 5 below:

Material Crosslinked polystyrene Copolymer of: activated styrenedivinylbenzene Nano organosilica Charcoal Average pore diameter (nm) 5-10 8 6-20 <2 (TBC) Temperature (range) (° C) -20- 120 - 20 - 300 <220 - Bulk density illlMilllllll 600 550 - 650 320 450 - 540 Average particle size (mm) 0.44 - 0.54 0.4 - 0.8 0.25 0.9

Table 5: Examples of Adsorbents Used When the solid adsorbent is no longer able to sufficiently absorb the target organic compounds, a first step 103 of desorption of the solid adsorbent medium is carried out, according to the desorption method described previously.

After step 103, the adsorbent medium resulting from the desorption process, referenced "ADS2" in the figures, can be reused in the adsorption step 101.

The (optional) step 102 of determining a saturation level of the solid adsorbent medium can comprise:

a step of measuring an aqueous effluent parameter subsequent to the adsorption step, and

a step of comparing the measured parameter with a predetermined threshold value making it possible to determine whether the saturation level of the solid adsorbent medium is reached or exceeded.

The first desorption step 103 is started when the saturation level of the solid adsorbent medium is reached, or exceeded (that is to say when the threshold value is reached).

The first desorption step 103 includes, or even consists of, the desorption process.

The measured parameter can be the Total Organic Carbon (TOC) content and / or the content of oils in the effluent (Oil in Water).

FIG. 4 illustrates a variant of the process for treating an aqueous effluent containing organic compounds. It comprises, in addition to the steps illustrated in FIG. 3, a second step 104 of desorption (regeneration) of at least part of the desorption liquid.

The second step of desorption of the spent desorption liquid is done by separating the desorption liquid from the contaminating organic compounds (BTEX, Phenols, PAH), said contaminating organic compounds having been recovered by the desorption liquid by desorbing the adsorbent medium. solid.

The second desorption step is carried out by one of the following methods, capable of heating the desorption liquid in order to separate it from the contaminating organic compounds, or a combination of these methods:

- a fractional distillation stage: preferred solution if the boiling temperature of the liquid is lower than the boiling temperature of the contaminants;

- an evaporation step followed by a solvent condensation step: one of the solutions advantageously selected if the boiling temperature of the liquid is higher than the boiling temperature of the contaminants;

- a stripping step with steam or gas in a packed column or with trays or in a membrane contactor: one of the solutions advantageously selected if the boiling temperature of the liquid is higher than the boiling temperature of contaminants.

In all cases, at least part of the desorption liquid recovered after the second desorption step, referenced "LIQ2" in the figures, can be recycled, in particular again as desorption liquid in the first desorption step 103 and the organic compounds can be recovered to be recovered.

Thus, the effluent treatment process makes it possible to recycle and / or recover the various compounds, adsorbent media, desorption fluid and organic compounds. This optimizes energy and material consumption and thereby reduces costs, and limits or even cancels the release of pollutants.

The treatment method is particularly advantageous in the offshore application, although other applications can be envisaged. Thus the water to be treated can be produced water, but also another type of effluent such as refinery effluents.

Claims (17)

1. A method for desorption of all or part of a solid adsorbent medium (ADS1) capable of adsorbing organic compounds from an aqueous effluent, said method comprising the following steps: - a step (10) of supplying an adsorbent medium resulting from an adsorption process at an adsorption temperature; - a step (20) of supplying a desorption liquid (LIQ1); a step (30) of bringing the desorption liquid into contact with all or part of the solid adsorbent medium, said contacting step comprising a step (40) of regulating a desorption temperature between a first temperature greater than or equal at the adsorption temperature and a second temperature below a boiling temperature of said desorption liquid. 2. Method according to claim 1, the desorption liquid (LIQ1) having a boiling temperature greater than or equal to 80 ° C. 3. Method according to one of claims 1 or 2, the desorption liquid (LIQ1) comprising an organic solvent, preferably polar, for example a compound of the glycol family. 4. Method according to claim 3, the desorption liquid (LIQ1) comprising Mono Ethylene Glycol (MEG). 5. Method according to one of claims 3 or 4, the desorption liquid (LIQ1) comprising Tri Ethylene Glycol (TEG). 6. Method according to one of the preceding claims, comprising a step of heating the desorption liquid (LIQ1) before the step (30) of bringing said desorption liquid into contact with all or part of the adsorbent medium. 7. Method according to one of claims 1 to 6, comprising a step of heating the adsorbent medium (ADS1), before and / or during the step (30) of bringing the desorption fluid into contact with said adsorbent medium. 8. The method of claim 7, the step of heating the adsorbent medium (ADS1) comprising injecting water vapor into said adsorbent medium. 9. Process for treating aqueous effluents containing organic compounds, said treatment process comprising the following steps: - an adsorption step (101) of the organic compounds from the aqueous effluent on a solid adsorbent medium; a step of determining (102) a level of saturation of the solid adsorbent medium, the step of determining comprising: • a step of measuring a parameter of the aqueous effluent consecutive to the adsorption step, and • a step of comparing the measured parameter with a predetermined threshold value making it possible to determine whether the level of saturation of the solid adsorbent medium is met or exceeded; a step for triggering a first desorption step (103) when the saturation level of the solid adsorbent medium is reached or exceeded, said first desorption step comprising the desorption process according to one of claims 1 to 8. 10. Treatment process according to claim 9, the measured parameter being the content of Total Organic Carbon (TOC) and / or the content of oils in the effluent. 11. A treatment method according to claim 9, further comprising a second desorption step (104) of the desorption liquid, subsequent to the first desorption step (103) of the adsorbent medium. 12. Device for desorption of a solid adsorbent medium, said device comprising: - means for determining an adsorption temperature of an adsorption process from which the solid adsorbent medium is derived; - means of supplying a desorption liquid; means for bringing the desorption liquid into contact with all or part of the adsorbent medium; said desorption liquid being at a desorption temperature; - means for regulating the temperature of the desorption liquid, preferably between a first temperature greater than or equal to the adsorption temperature and a second temperature below a boiling temperature of said desorption liquid. 13. Device according to claim 12, comprising first heating means capable of heating the desorption liquid before bringing said liquid into contact with the adsorbent medium. 14. Device according to one of claims 12 or 13, comprising second heating means capable of heating the adsorbent medium, preferably means for injecting water vapor onto said adsorbent medium. 15. Device for treating aqueous effluents, comprising: - adsorption means comprising at least one solid adsorbent medium; - Means for measuring at least one parameter of the aqueous effluent leaving the adsorption means in the solid adsorbent medium; - a device for desorbing said solid adsorbent medium according to one of claims 12 to 14. 16. Treatment device according to claim 15, the measurement means being chosen from an online Total Organic Carbon (TOC) analyzer, or an online analyzer of oil in the effluent, for example an ultrasonic acoustic analyzer, a chemical fiber optic sensor, an image analyzer, a turbidimeter, a photoacoustic sensor, a UV fluorescence analyzer including laser induced fluorescence. 17. Use of a liquid for desorbing a solid adsorbent medium containing organic contaminants resulting from a process for the adsorption of an aqueous effluent at an adsorption temperature, said liquid being at a desorption temperature greater than or equal to the adsorption temperature and less than or equal to its boiling point.