Process for separating a pollutant from an effluent gas

Abstract

Method for separating a pollutant from an effluent gas. The invention relates to a plant for treating a polluted effluent gas, comprising: a compressor (101) including: - an inlet; - a compression zone including a compression device and a sealing fluid ensuring the tightness of the path of the polluted effluent gas in the compression zone, the compression device being capable of compressing the polluted effluent gas; and - an outlet; and a separator (103) including: - a gas inlet (201), - a separation device configured to separate the pollutant present in the compressed polluted effluent gas by recovering it in an absorption fluid from the remainder of the compressed polluted effluent gas in order to obtain a treated compressed effluent gas (7), and - a gas outlet (202). Figure for the abstract: Fig. 1

Description

Title of the invention: Process for separating a pollutant from an effluent gas. Technical field

[0001] The invention relates to the field of purification of an effluent gas containing pollutants. Previous technique

[0002] Pyrolysis is a process for decomposing a product useful in many industrial processes. The gases used in pyrolytic processes are generally considered waste after use because the temperature and pressure conditions in the pyrolytic chamber lead to the formation of by-products that remain in the effluent gas, rendering it unsuitable for direct reuse. However, pyrolytic processes do not always consume all of the gas introduced into the pyrolytic chamber, and the effluent gas may contain still-recoverable species in addition to the by-products. It would be desirable to purify the effluent gas of the polluting by-products it contains in order to reuse the recoverable species from the purified effluent gas. Processes for separating recoverable species from pyrolytic process effluent gases have been proposed, for example, in document WO 03 / 047725.However, it remains in the interest of a person skilled in the art to propose improvements to such processes. Description of the invention

[0003] The invention aims specifically at improving existing effluent gas treatment processes and proposes for this purpose an installation for treating polluted effluent gas, comprising at least: - a compressor comprising: - an inlet intended to be supplied by the polluted effluent gas; - a compression zone comprising a compression device and a sealing fluid ensuring the tightness of the path of the polluted effluent gas within the compression zone, the compression device being capable of compressing the polluted effluent gas; and - an outlet designed to be traversed by the compressed polluted effluent gas; and - a separator comprising: - a gas inlet connected to the compressor outlet and intended to be supplied by the compressed polluted effluent gas, - a separation device configured to separate the pollutant present in the compressed polluted effluent gas by recovering it in an absorption liquid of the remaining polluted effluent gas compressed to obtain a treated compressed effluent gas, and - a gas outlet intended to be traversed by the treated compressed effluent gas.

[0004] This installation makes it possible to obtain a particularly efficient separation of the pollutant. In particular, carrying out the separation under pressure improves the recovery of the pollutant in the absorption liquid.

[0005] Furthermore, the use of a compressor containing a sealing fluid ensures that pollutants present in the exhaust gas do not agglomerate within the compressor. Indeed, in a compressor using a sealing fluid, if pollutants condense and form a solid phase, this solid phase is carried out of the compressor by the sealing fluid rather than forming deposits in the compression zone. This results in a longer service life for the compressor.

[0006] For example, the compressor can be chosen from a wet rotor compressor, a wet rotor pump, a liquid ring pump, a lubricated screw compressor, a lubricated piston compressor and a lubricated vane compressor.

[0007] In one embodiment, the compressor has a compression ratio greater than 1 and preferably greater than 2. The compression ratio corresponds to the ratio between the absolute pressure of the polluted effluent gas compressed at the outlet of the compressor and the absolute pressure of the polluted effluent gas at the inlet of the compressor.

[0008] In one embodiment, the separator is an absorption column further comprising: - an absorption liquid inlet intended to be supplied by the absorption liquid; - an absorption liquid outlet intended to be traversed by the absorption liquid loaded with the pollutant; the absorption liquid inlet and outlet being arranged so that the absorption liquid and the polluted compressed effluent gas flow in an absorption zone of the separator in counter-current to each other.

[0009] This embodiment allows for particularly efficient separation via the use of an absorption column and the counter-current circulation of the absorption liquid and the compressed polluted effluent gas.

[0010] In one embodiment, the installation includes an introduction device, configured to cool and pressurize the absorption liquid before its entry into the separator.

[0011] In such an embodiment, the separation is further improved, since the compressed polluted effluent gas is hotter than the cooled absorption liquid. Thus, the The pollutant partition coefficient between the effluent gas and the absorption liquid is shifted in favor of pollutant migration towards the absorption liquid. This results in a greater affinity of the pollutant for the absorption liquid and therefore better separation.

[0012] In one embodiment, the introduction device can be broken down into two elements, one allowing the absorption liquid to be pressurized, and the other allowing it to be cooled.

[0013] For example, the introduction device may include a pump for pressurizing the absorption liquid and a heat exchanger configured so that the absorption liquid transfers heat to a colder flow, and thus cools down.

[0014] In one embodiment, the installation further comprises a purifier including:

[0015] - an inlet configured to be supplied by the absorption liquid charged with pollutant; - a purification device configured to separate the pollutant from the pollutant-laden absorption liquid in order to obtain a purified absorption liquid; - an outlet intended to be traversed by the purified absorption liquid.

[0016] The purifier makes it possible to purify the absorption liquid, thus giving it greater efficiency during subsequent use.

[0017] In this way, the pollutants initially present in the effluent gas and which have moved towards the absorption liquid in the separator can be separated from the absorption liquid.

[0018] In one embodiment, the purifier is a desorption column, further comprising: - a gas inlet intended to be supplied by a recovery gas; - a gas outlet intended to be traversed by the recovery gas laden with pollutants; the gas inlet and outlet being arranged so that the polluted absorption liquid and the recovery gas flow in opposite directions within the purification device.

[0019] For example, the recovery gas can be an inert gaseous phase, for example nitrogen. In this embodiment, the pollutant is therefore separated from the polluted effluent gas in the separator and then recovered at the end of the process in an inert gas phase, which allows for simplified reprocessing of the pollutant.

[0020] For example, the reprocessing of the recovery gas containing a pollutant can be by thermal destruction or by condensation, in order to recover the pollutant and restore the recovery gas.

[0021] In another embodiment, the recovery gas may be chosen to have a better affinity for the pollutant than an inert gas, for example, better than nitrogen. In one embodiment, the recovery gas may be natural gas in the case of an organic pollutant such as a hydrocarbon. In this embodiment, the choice of natural gas also increases the calorific value of the gas mixture containing the pollutant, thus facilitating its subsequent thermal destruction.

[0022] In one embodiment the installation further includes a conditioning device configured to heat and expand the absorption liquid loaded with pollutant before its entry into the purifier.

[0023] This embodiment allows for even better purification of the pollutant-laden absorption liquid because by increasing its temperature and decreasing its pressure, the distribution equilibrium of the pollutant between the absorption liquid and the recovery gas is shifted in favor of greater migration towards the recovery gas.

[0024] In one embodiment, the inlet of the purifier is in communication with an absorption liquid outlet of the separator, and an absorption liquid inlet of the separator is in communication with the outlet of the purifier.

[0025] This embodiment allows for continuous recycling of the absorption liquid, as the absorption liquid becomes contaminant-laden in the separator and is then sent to the purifier where it is purified and then sent back to the separator. Continuous recycling in this embodiment allows for the use of a reduced quantity of absorption liquid while ensuring excellent separation, since the absorption liquid used in the separator is always freshly purified, and the separation rate is even better when the absorption liquid used in the separator is less contaminated.

[0026] Of course, it is possible that the introduction and / or conditioning devices described above may be arranged between the outlet of the purifier and the inlet of the separator on the one hand, and the outlet of the separator and the inlet of the purifier on the other. This particular embodiment makes it possible to obtain all the effects described above.

[0027] According to another aspect, the invention relates to a method for separating a pollutant from a polluted effluent gas using an installation as described above, comprising: - the compression of the polluted effluent gas in the compressor in order to obtain the compressed polluted effluent gas; and - the separation of the pollutant in the compressed polluted effluent gas towards an absorption liquid carried out in the separator.

[0028] In one embodiment, when the process is implemented in an installation comprising a purifier as described above, the process further includes the purification of the polluted absorption liquid in the purifier.

[0029] This purification further reduces the cost of the process because the absorption liquid is no longer consumed but can be purified, and if necessary reused.

[0030] In one embodiment, the process continuously comprises (i) loading the absorption liquid with pollutant during separation, (ii) purifying the absorption liquid loaded with the pollutant and (iii) introducing the purified absorption liquid through an absorption liquid inlet of the separator.

[0031] This embodiment allows the process to operate continuously, while ensuring that the separation in the separator is always optimal, because the absorption liquid then contains a minimum of pollutant, which therefore promotes the migration of the pollutant from the polluted compressed effluent gas to the absorption liquid.

[0032] In addition, the overall cost of the process is reduced because it is not necessary to renew the absorption liquid as it is used.

[0033] In one embodiment, the polluted effluent gas is chosen from an effluent gas from a chemical vapor deposition process, for example a process using a reagent comprising a hydrocarbon or a mixture of hydrocarbons, in particular a chemical vapor infiltration process, or from a biomass pyrolysis process.

[0034] In one embodiment, the absorption liquid and the cooling liquid have the same composition, that is to say they constitute identical compounds.

[0035] This embodiment is particularly advantageous because it allows the polluted effluent gas and the absorption liquid to come into contact immediately upon entering the compressor. Furthermore, this embodiment simplifies the process setup, as the absorption liquid circuit and the sealing liquid circuit can share components. Brief description of the drawings

[0036] [Fig-1] Fig. 1 is a schematic representation of one embodiment of the invention. Description of the implementation methods

[0037] The invention is now described by means of figures which shall not be considered as limiting the invention. These figures also only describe certain particular embodiments to aid understanding, and these embodiments shall not be interpreted as limiting the invention. Finally, the figures describe several embodiments in combination, without these embodiments necessarily having to be combined to obtain the technical effects.

[0038] The invention is now described by means of [Fig. 1], which schematically represents an installation according to one embodiment of the invention.

[0039] In the embodiment shown, the polluted effluent gas 1 enters a compressor 101. As described above, the compressor comprises a compression device and a sealing fluid (not shown separately in [Fig. 1]) ensuring the sealing of the path of the polluted effluent gas in the compression zone. Such a compressor 101 is known per se. For example, the compressor 101 may be a wet rotor compressor, a wet rotor pump, a liquid ring pump, a lubricated screw compressor, a lubricated piston compressor, or a lubricated vane compressor.

[0040] The compressor 101 allows the compression of the polluted effluent gas to obtain, after passing through the compression zone of the compressor, the compressed polluted effluent gas which is evacuated from the compressor 101 through an outlet.

[0041] For example, the compression ratio obtained in the compressor is greater than or equal to 1, preferably greater than or equal to 2, or even better greater than or equal to 5. For example, the absolute pressure of the compressed polluted effluent gas, reached at the outlet of the compressor, can be greater than or equal to 2.5 bars.

[0042] A reservoir 102 can be connected to the outlet of the compressor 101. The sealing fluid can circulate in a closed loop between the reservoir 102 and the compressor 101. Arrow 2 represents, together, the flow of compressed polluted effluent gas and the flow of the sealing fluid exiting the compressor 101 towards the reservoir 102. The sealing fluid separates from the compressed polluted effluent gas in the reservoir 102. The sealing fluid then returns to the compressor 101 and the compressed polluted effluent gas flows towards the separator 103.

[0043] It may be advantageous, since the compression of the polluted effluent gas 1 generates heat, to cool the sealing liquid 3 leaving the tank 102 before it returns to the compressor 101.

[0044] As shown, the sealing fluid 3 can pass through a heat exchanger 110, where it is cooled by a coolant 5, so that the sealing fluid 4 leaving the exchanger 110 has been cooled and the coolant 6 leaving the exchanger 110 has been heated.

[0045] In some embodiments, the sealing fluid can also play a role in cooling the compressor.

[0046] In the embodiment shown, the separator 103 is an absorption column which corresponds to a device known per se.

[0047] In the embodiment shown, an absorption liquid 17 is introduced through an absorption liquid inlet in the upper part of the absorption column 103, and the compressed polluted effluent gas enters through a gas inlet 201 of the column 103 located in a lower part thereof which communicates with the reservoir 102.

[0048] In the embodiment shown, the compressed polluted effluent gas passes through the absorption column 103 against the current of the absorption liquid 17 which, by gravity, flows in the column 103 until its gas inlet 201 which defines an absorption liquid outlet opening into the reservoir 102.

[0049] The treated compressed effluent gas 7 can exit through a gas outlet 202 located at the top of the column 103, after the pollutant has migrated to the absorption liquid.

[0050] In one embodiment, the absorption liquid is chosen so that the affinity of the pollutant for the absorption liquid is as high as possible. It is particularly advantageous to choose an absorption liquid that is a solvent for the pollutant. Indeed, the better the affinity of the pollutant for the absorption liquid, the better the separation. It should be noted that the sealing liquid can also be chosen so that it is also a solvent for the pollutant.

[0051] In an embodiment in which the pollutant is a benzene hydrocarbon (BTX) such as benzene, toluene, ethylbenzene, xylene, or a polycyclic aromatic hydrocarbon (PAH). In this embodiment, the absorption liquid may be selected from the following product families: hydrotreated or untreated mineral oils, synthetic oils, esters (vegetable oils), and mixtures of compounds from these families.

[0052] This embodiment is particularly preferred when the effluent gas is derived from a pyrolytic gas used for pyrocarbon deposition, particularly in the context of the densification of composite materials.

[0053] Alternatively, where the pyrolytic gas is derived from biomass processing, the pollutant is generally a compound selected from a benzene hydrocarbon (BTX) such as benzene, toluene, ethylbenzene, xylene, or a polycyclic aromatic hydrocarbon (PAH), or an oxygenated compound such as phenol, cresol, or a compound comprising heteroatoms. The pollutant may also be a mixture of one or more elements from the preceding list. In this embodiment, the absorption liquid may be selected from polar solvents having a good affinity for pollutants.

[0054] In the illustrated embodiment, the tank 102 is constructed so that the sealing fluid and the absorption fluid do not mix. For example, the tank 102 may be provided with a partition 111, allowing the separation of the absorption fluid and the sealing fluid, but allowing the passage of the compressed effluent gas from the compressor 101 to the separator 103, for example above of partition 111. Alternatively, it is also possible to use two separate capacities connected together.

[0055] In one embodiment, the absorption liquid can be chosen with the same composition as the sealing liquid, i.e. they constitute identical compounds.

[0056] Such an embodiment is particularly advantageous, because the migration of the pollutant towards the absorption liquid can begin as soon as the polluted effluent gas 1 comes into contact with the sealing liquid in the compressor 101.

[0057] Moreover, this embodiment makes it possible to avoid the distinction between the sealing liquid and the absorption liquid in the tank 102, and therefore makes it possible to do without the partition 111, and also makes it possible to ensure that vapors of the sealing liquid possibly passed into the gaseous phase and transported by the compressed polluted effluent gas exiting the compressor 101 are then also recovered in the absorption liquid in the separator 103.

[0058] This embodiment, in which the sealing liquid has the same composition as the absorption liquid, therefore allows for even better separation of the pollutant and a simplified process as a whole.

[0059] In the embodiment shown in [Fig. 1], the pollutant-laden absorption liquid can be conveyed from the reservoir 102 to the inlet configured to be supplied by the pollutant-laden absorption liquid from a purifier 107.

[0060] In one embodiment, the purifier 107 is a desorption column which corresponds to a device known per se.

[0061] As described above, in one embodiment the absorption liquid 17 introduced into the separator 103 can be, beforehand, cooled for example by a heat exchanger 104 and pressurized for example by a pump 108 while the pollutant-laden absorption liquid 11 introduced into the purifier 107 can be heated for example by a heat exchanger 104 and expanded for example by a valve 106, for example to atmospheric pressure (1 bar) before its introduction.

[0062] For example, the temperature of the compressed polluted effluent gas at the outlet of compressor 101 or at the inlet of separator 103 is advantageously between 5 and 30°C to ensure good industrial compatibility of the process.

[0063] The specific choice of process parameters will be made according to the physical properties of the chosen absorption liquid, and in particular with regard to its cold density and vapor pressure. Specifically, the temperature in the separator 103 will be chosen so that the viscosity of the absorption liquid is sufficiently low to avoid significant pressure drops.

[0064] Similarly, the temperature in the purifier 107 will be chosen low enough so that the absorption liquid cannot vaporize, and thus significant losses of absorption liquid are avoided.

[0065] Examples of temperatures and pressures in a process of the invention are given for a particular embodiment described in the example part below.

[0066] These characteristics make it possible to improve respectively the migration of the pollutant from the compressed polluted effluent gas to the absorption liquid 17 in the separator 103, and the desorption of the pollutant from the pollutant-laden absorption liquid 11 in the purifier 107.

[0067] In one embodiment, the pollutant-laden absorption liquid 8 can pass through a heat exchanger 104 before being introduced into the purifier 107 in order to be heated.

[0068] The heat exchanger 104 through which the pollutant-laden absorption liquid 8 passes allows a heated absorption liquid 9 to be obtained at the outlet before its introduction into the purifier 107. Heating the absorption liquid 9 before introducing it into the purifier 107 is advantageous because a higher temperature of the absorption liquid in the purifier 107 improves the separation of the pollutant in the purification device.

[0069] Similarly, in one embodiment, the absorption liquid loaded with pollutant 9 can pass, before the inlet of the purifier, through a valve 106 allowing its expansion.

[0070] The valve 106 is intended to relax the heated pollutant-laden absorption liquid 9 before its introduction into the purifier 107. Indeed, a lower pressure of the pollutant-laden absorption liquid in the purifier 107 further improves the separation of the pollutant in the purifier 107.

[0071] It is understood that the heat exchanger 104 and the valve 106 may or may not be present independently of each other and may be arranged in any order. Furthermore, alternatively, if a higher temperature than that achievable by the heat exchanger 104 is desired for the pollutant-laden absorption liquid 9, additional heating means may be provided upstream of the purifier 107. For example, an additional heating means may be provided between the heat exchanger 104 and the valve 106.

[0072] However, in embodiments where the pollutant-laden absorption liquid 8 is under pressure, for example because it has been introduced under pressure into the separator 103, it is preferable that the valve 106 be located after the heat exchanger 104, and where applicable after any additional heating means, since the pressure of the pollutant-laden absorption liquid then overcomes the pressure losses of these components without requiring additional elements. Furthermore, pressurizing the pollutant-laden absorption liquid 8 prevents the occurrence bubbles are released up to valve 106, thus preventing any vaporization of volatile compounds.

[0073] The heat exchanger 104 and the valve 106 can form a conditioning device as described above.

[0074] In the embodiment shown, the purifier 107 is a desorption column.

[0075] The pollutant-laden absorption liquid 11 is introduced into the inlet configured to be fed by the pollutant-laden absorption liquid from the purifier, arranged at the top of the desorption column 107.

[0076] In the embodiment shown, the desorption column 107 is further supplied by a gaseous phase 13.

[0077] In one embodiment, the gaseous phase 13 may be nitrogen or natural gas. The gaseous phase 13 is chosen so that the affinity of the pollutant for said gaseous phase is as high as possible, thereby improving the efficiency of the purifier 107.

[0078] In the embodiment shown, the desorption column 107 is provided with an outlet intended to be traversed by the purified absorption liquid shown at the bottom of the column 107 in [Fig.1], which is traversed by the purified absorption liquid 12.

[0079] The gaseous phase 13 becomes charged with pollutant in the column 107, and the gaseous phase charged with pollutant 14 passes through an outlet intended to be passed through by a gaseous phase represented on the [Fig.1] at the top of the column 107.

[0080] In the embodiment shown, the purified absorption liquid 12 passes through a compressor 108 configured to pressurize the purified absorption liquid 15.

[0081] In the embodiment shown, the compressed purified absorption liquid 15 can be cooled by means of a heat exchanger 104 before its introduction into the separator 103.

[0082] In the embodiment shown, the heat exchanger 104 is traversed on the one hand by the cold pollutant-laden absorption liquid 8 which needs to be heated and on the other hand by the hot purified absorption liquid 15 which needs to be cooled, so that at the outlet of the heat exchanger 104, the pollutant-laden absorption liquid 9 comes out hotter and the purified absorption liquid 17 comes out colder.

[0083] In this embodiment, the process is even more economical because part of the thermal energy is supplied by the absorption liquid itself, which reduces the amount of heat to be supplied and therefore the overall cost of the process.

[0084] However, for the process of the invention, it is not necessary for the same heat exchanger 104 to be traversed by the absorption liquid loaded with pollutant 8 and by the purified absorption liquid 15. In one embodiment, the liquid absorbing material loaded with pollutant 8 or the purified absorbing material 15 can be heated or cooled by heating or cooling elements separate from each other.

[0085] The purified absorption liquid 17, having passed through the heat exchanger, is cooled. It can be directly introduced into the inlet of the separator intended to be supplied with the absorption liquid.

[0086] Alternatively, and not shown in [Fig. 1], if an even lower temperature than that achievable with the heat exchanger 104 is desired for the purified absorption liquid 17, additional cooling elements may be provided before the inlet of the separator 103 configured to be supplied with the absorption liquid. For example, one (or more) additional cooling element may be provided between the heat exchanger 104 and the separator 103. The heat exchanger 104, the compressor 108, and any additional cooling element may be present independently of each other and are not necessarily arranged in the order shown in [Fig. 1].

[0087] However, in an embodiment where a heat exchanger 104 and a compressor 108 are present, it is advantageous to arrange the compressor 108 before the heat exchanger 104 so that it is not necessary to add an element to overcome the pressure losses in the purified absorption liquid circuit.

[0088] The compressor 108 and the heat exchanger 104 can form an introduction device as described above. They can be present in embodiments where the absorption liquid 12 does not come from a purifier but, for example, from an absorption liquid reservoir.

[0089] The presence of the purifier 107 is not required to obtain the effect described above, and other embodiments without the presence of a purifier 107 are considered. For example, in an embodiment not shown, the liquid outlet of the separator is not connected to the purifier 107, and the contaminated absorption liquid accumulates at the bottom of the tank 102. When the separation is complete, the absorption liquid can then be purified independently of the separation circuit, or replaced.

[0090] This embodiment is preferred when the amount of pollutant is low. It is then not necessary to purify the absorption liquid too frequently, because it becomes only slightly contaminated, and the separation therefore remains sufficiently efficient throughout the passage of the effluent gas.

[0091] In this embodiment, it is possible to recover the absorption liquid loaded with pollutants once the separation is complete and to purify it, for example in a purifier similar to the one described above.

[0092] In an alternative embodiment not shown, the absorption fluid and the sealing fluid may be identical, and the separator may be a filter impermeable to the sealing fluid, located directly at the compressor outlet. The separator is therefore not necessarily an absorption column.

[0093] In this embodiment, the sealing fluid is in contact with the contaminated effluent gas from the moment the contaminated effluent gas enters the compressor and becomes saturated with pollutants throughout the compression process. The filter located at the compressor outlet ensures that the pollutant that has migrated into the sealing fluid is retained by the filter within the sealing fluid in the compressor.

[0094] In this embodiment, the sealing fluid can also be continuously purified, for example by adapting a purifier to the cooling circuit normally present for the compressor sealing fluid.

[0095] In this embodiment, the sealing fluid may also not be continuously purified but only purified once the separation is complete. This embodiment is particularly preferred when the polluted effluent gas contains a small amount of pollutant, and the sealing fluid is only slightly polluted, even at the end of the separation. Examples

[0096] The embodiment described by way of example is only one possible embodiment and should not be interpreted restrictively. In particular, the numerical values ​​that follow are given only to illustrate a particular embodiment, and the invention is not limited to these values ​​alone.

[0097] The polluted effluent gas 1 upstream of the compressor 101 is at 1 bar and 20°C. The compressed polluted effluent gas leaves the compressor 101 at 3 bar and 20°C.

[0098] The compressor 101 is supplied with a sealing liquid 4 at a temperature of 10°C. The latter leaves the compressor at 20°C, like the compressed polluted effluent gas.

[0099] Before being reintroduced into the compressor 101, the heated sealing fluid 3 is cooled by means of a heat exchanger 110, in which its temperature drops from 20°C to 10°C. Then, the cooled sealing fluid 4 is reintroduced into the compressor 101.

[0100] The compressed polluted effluent gas enters an absorption column 103. There, it is brought into contact with an absorption liquid 17 at 10°C and 3 bar. The treated compressed effluent gas leaves the absorption column at a temperature of 10°C and an absolute pressure of 3 bar.

[0101] The absorbent liquid loaded with pollutant 8 leaves the absorbent column 103 at a temperature of 13°C and 3 bar and then passes into a conditioning device including a heat exchanger 104, an additional heating element and a valve 106.

[0102] In the conditioning device, the absorbent liquid containing the pollutant 8 first passes through the heat exchanger 104, where its temperature is raised from 13°C to 68°C. The absorbent liquid containing the pollutant 8 then passes through the additional heating element, not shown in [Fig. 1], where its temperature increases to 80°C. The absorbent liquid then passes through the valve 106, which it exits at an absolute pressure of 1 bar and a temperature of 80°C.

[0103] The absorbent liquid loaded with pollutant 8 then enters a desorption column 107, where it is brought into contact with a gaseous phase 13. The gaseous phase 13 enters the desorption column 107 at a temperature of 15 °C and an absolute pressure of 1.03 bar. The gaseous phase leaves the column loaded with pollutant 14. The gaseous phase loaded with pollutant 14 exits the desorption column 107 at a temperature of 80 °C.

[0104] The purified absorption liquid 12 leaves the desorption column at a temperature of 75°C and an absolute pressure of 1 bar.

[0105] The purified absorption liquid 12 then enters an introduction device comprising a pump 108, a heat exchanger 104 identical to the heat exchanger 104 of the conditioning device and an additional cooling element.

[0106] The purified absorption liquid 12 first passes through the pump 108 in which its absolute pressure increases from 1 bar to 3 bars.

[0107] The compressed purified absorption liquid 15 then enters the heat exchanger 104 in which its temperature drops from 75°C to 20°C.

[0108] The purified absorption liquid, cooled for the first time, then passes into the additional cooling element, not shown, in which its temperature drops from 20°C to 10°C.

[0109] The purified absorption liquid 17 can then be reintroduced directly into the absorption column 103.

[0110] In a second example, the invention is now described by means of an example illustrating the advantage of carrying out the separation under pressure.

[0111] A gas from a pyrolysis process comprising by mass fraction 63.5% methane, 5.2% hydrogen, 14.5% ethylene, 5.8% acetylene, 4.4% benzene hydrocarbon compounds (BTX: benzene, toluene, xylene) and 6.6% polycyclic aromatic hydrocarbon compounds (naphthalene, ethylbenzene among others) is introduced at different temperatures and pressures into an absorption column, all other things being equal.

[0112] Table 1 lists the residual levels of benzene hydrocarbons and polycyclic aromatic hydrocarbon compounds after separation for the different separations carried out.

[0113] [Tables 1] ...........?..... ..........1............................... 3 bsrs îwttf et jm JW s ppsrs imskîZ trB BÎX 3S 313.49 8434 / 9 >4 <3' sIüZS zv W | 40.34 1130 | 0 «æ 4;48 | oim 333 3088 v 3581 1.48 0.95 83? | - <: 0.21 894 8.8$ 1 ia » 3U> ....." V............ » 130

[0114] The pressure values ​​in Table 1 are expressed in absolute bars.

[0115] Reading Table 1 demonstrates that the separation with an effluent gas under pressure is better than that obtained in the case of an effluent gas of lower pressure.

[0116] Furthermore, Table 1 demonstrates that the separation is better when the effluent gas is cold, and thus confirms the advantage of a cooled absorption liquid.

Claims

Demands

1. Installation for the treatment of a polluted effluent gas, comprising at least: - a compressor (101) comprising: - an inlet intended to be supplied by the polluted effluent gas (1); - a compression zone comprising a compression device and a sealing fluid ensuring the sealing of the path of the polluted effluent gas in the compression zone, the compression device being capable of compressing the polluted effluent gas; and - an outlet intended to be traversed by the compressed polluted effluent gas;and - a separator (103) comprising: - a gas inlet (201) in communication with the compressor outlet and intended to be supplied by the compressed polluted effluent gas, - a separation device configured to separate the pollutant present in the compressed polluted effluent gas by recovering it in an absorption liquid from the rest of the compressed polluted effluent gas in order to obtain a treated compressed effluent gas (7), and - a gas outlet (202) intended to be traversed by the treated compressed effluent gas, the installation further comprising a purifier (107) comprising: - an inlet configured to be supplied by the pollutant-laden absorption liquid (11); - a purification device configured to separate the pollutant from the pollutant-laden absorption liquid in order to obtain a purified absorption liquid;- an outlet intended to be traversed by the purified absorption liquid (12) and in which the inlet of the purifier (107) is in communication with an absorption liquid outlet of the separator, and in which a liquid inlet; The absorption of the separator is in communication with the outlet of the purifier, the installation further comprising a tank (102) in communication with the outlet of the compressor and allowing the passage of the compressed effluent gas from the compressor to the separator, the tank being provided with a partition (111), allowing the separation of the absorption liquid and the sealing liquid, but allowing the passage of the compressed effluent gas from the compressor to the separator, for example above the partition.

2. Installation according to claim 1, wherein the compressor (101) is selected from a wet rotor compressor, a liquid ring pump, a wet rotor pump, a lubricated screw compressor, a lubricated piston compressor and a lubricated vane compressor.

3. An installation according to claim 1 or 2, wherein the separator (103) is an absorption column further comprising: - an absorption liquid inlet for being supplied by the absorption liquid (17); - an absorption liquid outlet for being traversed by the pollutant-laden absorption liquid (8); the absorption liquid inlet and outlet being arranged so that the absorption liquid and the polluted compressed effluent gas flow in an absorption zone of the separator in counter-current to each other.

4. Installation according to any one of claims 1 to 3, comprising an introduction device (104, 108), configured to cool and pressurize the absorption liquid before its entry into the separator (103).

5. Installation according to claim 1 further comprising a conditioning device (104, 106) configured to heat and expand the pollutant-laden absorption liquid before its entry into the purifier.

6. A method for separating a pollutant from a polluted effluent gas (1) employing an installation according to any one of claims 1 to 5, comprising: - the compression in the compressor (101) of the polluted effluent gas in order to obtain the compressed polluted effluent gas; and - the separation of the pollutant in the compressed polluted effluent gas into an absorption liquid carried out in the separator (103).

7. Separation method according to claim 6, employing an installation according to any one of claims 1 to 6 further comprising the purification of the polluted absorption liquid in the purifier (107).

8. A separation method according to claim 7, wherein the method continuously comprises (i) loading the absorbent liquid with pollutant during separation, (ii) purifying the absorbent liquid loaded with the pollutant and (iii) introducing the purified absorbent liquid through an absorbent liquid inlet of the separator.

9. A separation process according to any one of claims 6 to 8, wherein the polluted effluent gas (1) is selected from an effluent gas from a chemical vapor deposition process, for example a process using a reagent comprising a hydrocarbon or a mixture of hydrocarbons, in particular a chemical vapor infiltration process, or from a biomass pyrolysis process.

10. Separation method according to any one of claims 6 to 9, wherein the absorption liquid is cooled by a coolant, and wherein said coolant and absorption liquid have the same composition.

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