Method and device for deacidifying a gaseous effluent comprising derivatives of an absorbent solution loaded with acid compounds

Abstract

The invention relates to a device and a method for deacidifying a gaseous effluent (EF) including acid compounds, in which the following steps are carried out: a) the gaseous effluent (EF) is placed in contact with an absorbent solution (SAR); b) the absorbent solution loaded with acid compounds (SA) is separated into a gaseous fraction (FG), a first liquid fraction (FL1) and a second liquid fraction (FL2); c) the absorbent solution (SA) and / or the second liquid fraction (FL2) is heated in at least two heat exchangers (E101A, E101B); d) a first portion of absorbent solution (SA) is diverted upstream of the first heat exchanger (E101A) and a second portion is diverted downstream of the first heat exchanger (E101A); e) the absorbent solution is regenerated so as to release the acid compounds into an outgoing gas stream, the absorbent solution depleted in acid compounds (SR) exiting the regeneration column (C102) and being recycled.

Description

[0001] METHOD AND DEVICE FOR DEACIDIFYING A GAS EFFLUENT COMPRISING DERIVATIONS OF AN ABSORBENT SOLUTION CHARGED WITH ACID COMPOUNDS

[0002] technical field

[0003] The present invention relates to the field of deacidification of a gas by means of an absorbent solution, for example the decarbonation of combustion fumes or the deacidification of natural or industrial gas.

[0004] The areas targeted are essentially low-pressure decarbonization processes (biogas from waste methanization, post-combustion CO2 capture: industrial fumes from waste incinerators, coal or natural gas power plants, blast furnaces, cement plants, glassworks, aluminium production, lime production, or even FCC type refinery gases for "Fluid Catalytic Cracking" meaning catalytic cracking of fluid,

[0005] The invention may also relate to high-pressure deacidification processes of natural gas and syngas.

[0006] Previous technique

[0007] Gas deacidification processes commonly employ aqueous amine solutions to remove acidic compounds from gases, including carbon dioxide (CO2), hydrogen sulfide (H2S), carbon oxysulfide (COS), carbon disulfide (CS2), sulfur dioxide (SO2), and mercaptans (RSH) such as methyl mercaptan (CH3SH), ethyl mercaptan (CH3CH2SH), and propyl mercaptan (CH3CH2CH2SH). The gas is deacidified by contacting it with the absorbent solution, which is then thermally regenerated.

[0008] In the energy sector, for example, the combustion of fossil fuels, which leads to the release of CO2 into the atmosphere, is a major problem, as the increase in atmospheric CO2 is recognized as a contributor to global warming. To reduce this type of emission, one solution is to capture and then store the CO2 emitted by combustion, particularly in coal-fired power plants. A CO2 capture process separates the CO2 from the other components of the flue gases produced by burning fossil fuels, thus allowing the CO2 to be transported in concentrated form to an underground storage facility. In this way, the CO2 is sequestered in the underground reservoir or used for other purposes instead of being released into the atmosphere. A current standard process for capturing CO2 involves scrubbing the combustion gases with a basic absorbent solution, such as an aqueous solution of monoethanolamine.The basic solution flows between two columns. One operates at a low temperature and scrubs the gas by absorbing acidic species such as CO2, but also H2S, SO2, COS, etc. The other operates at a high temperature and regenerates the absorbing solution by releasing the acidic species it contains. The temperature increase in the second column is due to heating the absorbing solution at the bottom of the regenerator using a heating agent, usually steam.

[0009] One drawback of this type of deacidification process lies in its high energy consumption. In a power plant, for example, the installation of a CO2 capture system reduces the plant's energy efficiency: part of the energy produced by the combustion of fossil fuels is consumed by the capture unit and is no longer used for electricity production.

[0010] It is therefore essential to minimize the energy consumption of such processes, in particular the energy consumption related to the regeneration of the absorbent solution.

[0011] Recently, it has been proposed to use absorbent solutions that have the property of forming two liquid phases that can be immiscible depending on the temperature or CO2 concentration. This phenomenon of the solution splitting into two immiscible phases is also called demixing. Patents FR 2,898,284 and EP1,656,983, for example, describe processes using this type of absorbent solution. In these processes, fractional regeneration is performed, consisting of regenerating only a portion of the absorbent solution from a step that separates the solution into two liquid phases upstream of the regeneration column. Thus, such fractional regeneration reduces the energy expenditure associated with regeneration and limits the size of the regeneration section.

[0012] The gas exiting the regeneration column consists primarily of acid gas (carbon dioxide (CO2), hydrogen sulfide (H2S), carbon oxysulfide (COS), carbon disulfide (CS2), sulfur dioxide (SO2), and RSH mercaptans such as methyl mercaptan (CH3SH), ethyl mercaptan (CH3CH2SH), and propyl mercaptan (CH3CH2CH2SH), for example) captured from the gaseous effluent in the absorption column, and water vapor. To store the acid gas, a condenser is generally used to condense the water vapor from the gas exiting the regeneration column into liquid form and to discharge it. However, the condenser generates dissipated heat, which represents an energy loss. Furthermore, the energy expenditure required to regenerate the absorbent solution is a key performance factor in an acid gas purification process by absorption. It is divided into three parts:

[0013] - the "sensible heat" which is the energy expended during the regeneration stage to heat the absorbing solution (this item is mainly related to the circulating flow rate of the absorbing solution, i.e. to the absorption capacity of the absorbing solution);

[0014] - the "Heat of reaction" which is the energy required to break the chemical bonds between the acid gas (CO2 for example) and the absorbing solution during the regeneration step;

[0015] - the "Heat of vaporization" (also called "heat of stripping") which is the energy of vaporization of water expended during the regeneration step of the absorbent solution.

[0016] US patent 9,956,505 B2 and US patent application 2010 / 0242731 A1 are known to address the improvement of energy efficiency and the reduction of energy consumption. However, these documents do not address absorbent solutions with demixing properties. Consequently, regeneration is applied to the entire absorbent solution, resulting in high energy consumption. Furthermore, the processes described in these documents still require improvements to enhance their thermal performance.

[0017] Summary of the invention

[0018] The invention seeks to improve the energy performance of the regeneration of the absorbing solution, in particular with the aim of recovering acidic compounds in industrial processes in order to capture and / or store and / or reuse them.

[0019] To this end, the invention may in particular seek to reduce the thermal consumption related to the regeneration of the absorbing solution and / or the heat dissipated in the condenser.

[0020] The invention relates to a process for deacidifying a gaseous effluent containing acidic compounds, such as hydrogen sulfide or sodium dioxide, in which at least the following steps are carried out: a) the gaseous effluent is contacted with an absorbent solution in an absorption column, so as to obtain a gaseous effluent depleted in acidic compounds and an absorbent solution loaded with acidic compounds, the absorbent solution being capable of forming separable phases when it has absorbed a predetermined quantity of acidic compounds and is heated, b) the absorbent solution loaded with acidic compounds is separated, in a separation means, into a gaseous fraction, a first liquid fraction depleted in acidic compounds and a second liquid fraction enriched in acidic compounds,(c) The absorbent solution loaded with acidic compounds is heated in at least one first heat exchanger, and the absorbent solution loaded with acidic compounds or the second liquid fraction is heated in at least one second heat exchanger, said first and second heat exchangers exchanging heat with an absorbent solution to be recycled; (d) At least one first portion of the absorbent solution loaded with acidic compounds is diverted in a first bypass line upstream of the first heat exchanger and sent to a regeneration column; (e) At least one second portion of the absorbent solution loaded with acidic compounds or the second liquid fraction is diverted in a second bypass line downstream of the first heat exchanger and sent to the regeneration column.(f) the first portion of the acid-laden absorbent solution from the first bypass line, the second portion of the acid-laden absorbent solution from the second bypass line or the second liquid fraction, and the remainder of the second liquid fraction are regenerated in a regeneration column so as to release the acid compounds in an outgoing gas stream, thus forming a regenerated acid-poor absorbent solution exiting the regeneration column; (g) the absorbent solution to be recycled is recycled as the absorbent solution from step (a), the absorbent solution to be recycled comprising at least the acid-poor absorbent solution regenerated in step (f) and preferably the first liquid fraction obtained in step (b).

[0021] Preferably, at least a part, preferably all, of the regenerated acid-poor absorbent solution exiting the regeneration column is taken and passed through a reboiler to generate steam, the steam being injected into the regeneration column to provide heat input.

[0022] Advantageously, the second liquid fraction is heated by a heater just before being injected into the regeneration column.

[0023] According to one configuration of the invention, the gaseous fraction is compressed in a compression means or expanded in an expansion means between the separation means and the regeneration column. Advantageously, the first portion is heated by direct exchange in the regeneration column or by indirect exchange with the gas stream exiting the regeneration column.

[0024] Preferably, the water vapor contained in the gas stream exiting the regeneration column is condensed in a condenser and the condensed water is removed from a separator tank.

[0025] Preferably, at least some of the condensed water removed from the separator tank is reinjected into the upper part of the regeneration column.

[0026] Alternatively or additionally, at least a portion of the condensed water discharged from the separator tank is mixed with the absorbing solution loaded with acidic compounds, between the absorption column and the first heat exchanger.

[0027] According to one configuration of the invention, the separation means is positioned between the first and second heat exchangers or between the second heat exchanger and the regeneration column.

[0028] According to one variant of the invention, the absorbent solution loaded with acidic compounds is heated in an additional heating means, upstream or downstream of the separation means, preferably between the first heat exchanger and the separation means or between the separation means and the second heat exchanger (or between the second heat exchanger and the regeneration column).

[0029] Preferably, the gaseous fraction exiting the separation means is injected into the regeneration column.

[0030] According to one embodiment of the process of the invention, said first portion and said second portion are mixed before entering the regeneration column, and the mixture of the first portion and the second portion is injected at a first altitude located above a second altitude where the second liquid fraction is injected into the regeneration column.

[0031] Advantageously, in the regeneration column, the first portion is injected at an altitude equal to or greater than that at which the second portion is injected, which is itself greater than that at which the second liquid fraction is injected. Preferably, the gaseous fraction is injected between the injection altitude of the first portion and the injection altitude of the second portion. Preferably, the flow in the first bypass line and / or the second bypass line is controlled by manual or automatic flow control means, preferably flow regulating valves.

[0032] According to one variant of the invention, in step c), the absorbent solution rich in acid compounds is heated in said first heat exchanger and in an intermediate heat exchanger and the second liquid fraction is heated in said second heat exchanger, said intermediate heat exchanger exchanging heat with the absorbent solution to be recycled.

[0033] Advantageously, in step e), the second portion of the absorbing solution loaded with acidic compounds is diverted into the second bypass line between the first heat exchanger and the intermediate heat exchanger, and a third portion of the second liquid fraction is diverted into a third bypass line between the separation means and the second heat exchanger, the third portion being sent to the regeneration column.

[0034] According to one variant of the invention, in the regeneration column, the third portion is injected at an altitude located between the injection altitude of the second portion and the injection altitude of the remainder of the second liquid fraction.

[0035] Preferably, fluid circulation in the third bypass line is controlled by manual or automatic flow control systems, preferably flow regulating valves.

[0036] Preferably, said absorbing solution comprises one or more reactive compounds, each selected from the group consisting of amines, alkanolamines, amino acids, alkali salts of amino acids, amides, ureas, phosphates, carbonates, and alkali metal borates, and preferably, each selected from the following list: monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxyethanol, N,N-dimethylaminoethoxyethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, N,N-bis-(3-dimethylaminopropyl)-N-isopropanolamine, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N,N-dimethylethanolamine, N-(2-aminoethylethanolamine, 3-amino-1-propanol, 3-ethoxypropylamine, N-methylethanolamine, N-methyldiethanolamine, diisopropanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethyl-1,3-propanediamine, N,N,N-tris(3-dimethylaminopropyl)amine, N,N,N',N",N'-pentamethyldipropylenetriamine, N,N,N',N'-tetramethyliminobispropylamine, N-(3-aminopropyl)morpholine, N-(2-dimethylaminoethyljmorpholine, 3-methoxypropylamine, N-(2-aminoethyl)piperazine, 2,2-dimorpholinodiethyl ether, N,N'-dimethylpiperazine, N,N,N',N',N"-pentamethyldiethylenetriamine, N-(3-aminopropyl)piperazine, ethyl 1-piperazine carboxylate, dipropylenetriamine, N,N-Bis(2,2-diethoxyethyl)methylamine, 3-butyl-2-(1-ethylpentyl)oxazolidine, 3-ethyl-2-methyl-2-(3-methylbutyl)oxazolidine, 1,2,2,6,6- pentamethyl-4-piperidone, 1-(2-methylpropyl)-4-piperidone, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetraethyliminobisethylamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, 1-phenylpiperazine, 1-formylpiperazine, ethyl 1-piperazine carboxylate, N,N'-di-tert-butylethylenediamine,4-Ethyl-2-methyl-2-(3-methylbutyl)oxazolidine, tetraethylenepentamine, triethylenetetramine, N,N-diethyldiethylenetriamine, N1-isopropyldiethylenetriamine, piperazine, N,N-dimethyldipropylenetriamine, diethylenetriamine, N-(2-aminoethyl)-1,3-propanediamine, 2,2'-(ethylenedioxy)diethylamine, 4-hydroxy-N-methylpiperidine, N-(2-aminoethyl)morpholine, 4-amino-2,2,6,6-tetramethylpiperidine, 1,2-diaminocyclohexane, 2-piperidinoethylamine, 2-(2-aminoethyl)-1-methylpyrrolidine, ethylenediamine, N,N-diethylethylenediamine, N-phenylethylenediamine, N-(3-aminopropyl)piperidine, furfurylamine, 2-(aminomethyl)thiophene, 4,9-dioxa-1,12-dodecanediamine, 4,7,10-trioxa-1,13-tridecanediamine, 1,2,4-trimethylpiperazine, 2-amino-2-methylpropanol, N,N'-diethyl-N,N'-dimethylethylenediamine, N,N-diethyl-N',N'-dimethylethylenediamine, 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4-dimethyl-1,4-diazacycloheptane,N-(2-dimethylaminoethyl)-N'-methylpiperazine, N,N,N',N'-tetraethylpropylenediamine, 1-[2-(1-piperidinyl)ethyl)]piperidine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, hexamethylenediamine, 1,2-propanediamine, 2-methyl-1,2-propanediamine, 2-methylpiperazine, N-2,N-2-dimethyl-1,2-propanediamine, N-1,N-1-dimethyl-1,2-propanediamine, 4,4'-ethylenedimorpholine, N,N,N',N'-tetraethyl-N'-methyldipropylenetriamine, 4-(dimethylamino)-1,2 2,6,6-pentamethylpiperidine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 1,5,9-trimethyl-1,5,9-triazacyclododecane, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, N,N'-difurfurylethylenediamine, 1,2-Bis(2-aminoethyl)thioethane, Bis(2-aminoethyl)disulfide, Bis(2-dimethylaminoethyl)sulfide, 2,6-dimethylpiperazine, 1-ethyl-3-piperidinamine, decahydroquinoxaline, 2,3,5,6-tetramethylpiperazine, N,N-dimethyl(2-piperidinyl)methanamine,1-(2-piperidinylmethyl)piperidine, 1-acetyl-2-diethylaminoethane, 1-amino-2-benzylaminoethane, 1-acetyl-3-dimethylaminopropane, 1-dimethylamino-3,3-diphenylpropane, N,N-dimethylbenzylamine, 2-(dimethylaminomethyl)thiophene, N,N,5-trimethylfurfurylamine, N,N-Bis(tetrahydro-2-furanylmethyl)amine, tetrahydroisoquinoline, 2-(ethylsulfanyl)ethanamine, thiomorpholine, 2-[(2-aminoethyl)sulfanyl]ethanol, 2,2-dimethyl-1,3-propanediamine, N1,N3,2-trimethyl-1,3-propanediamine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, N-1,N-1,2-tetramethyl-1,3-propanediamine, 1-methoxy-2-propanamine, 3-thiomorpholinylmethanol, 2-(butylamino)ethanethiol, Bis(2-diethylaminoethyl)ether, 1-dimethylamino-2-ethylmethylaminoethoxyethane, 1,2,3-triaminopropane and N-1-(2-aminopropyl)-1,2-propanediamine, tetrahydro-2-furanylmethylamine, 2,6-dimethylmorpholine,N-methyl(tetrahydro-2-furanyl)methanamine, N,N,N',N'-tetramethyl-1,4-butanediamine, bis(2-(N,N-dimethylamino)propyl)ether, bis(2-(N,N-dimethylamino)ethyl)ether, 1,3-bis(dimethylamino)-2-propanol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethyldiethylenetriamine, 1,2-bis(dimethylaminoethyl)ethane, 1-(2-piperidinylmethyl)piperidine, 1,2,3-triaminopropane, 1,2-propanediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1-Ethyl-3-piperidinamine, 1-Methoxy-2-propanamine, 2-(2-aminoethoxy)ethanol, 2-(aminomethyl)-2-methyl-1,3-propanediamine, 2-(aminomethyl)thiophene, 2,2-Dimethyl-1,3-propanediamine, 2,3,5,6-Tetramethylpiperazine, 2,6-Dimethylmorpholine, 2,6-Dimethylpiperazine, 2-Methyl-1,2-propanediamine, 2-Methylpiperazine, 3-Amino-1-propanol, 3-Ethoxypropylamine, bis(aminoethyl)sulfide, decahydroquinoxaline, dipropylenetriamine, furfurylamine,hexamethylenediamine, N-(2-aminoethyl)ethanolamine, N-(2-aminoethyl)piperidine, N-(3-aminopropyl)piperazine, N-(3-aminopropyl)piperidine, N,N-dimethyl(2-piperidinyl)methanamine, N-1-(2-aminopropyl)-1,2-propanediamine, N-1,N-1,2-tetramethyl-1,3-propanediamine, N-1,N-1-dimethyl-1,2-propanediamine, N-1,N-3,2-trimethyl-1,3-propanediamine, N-2,N-2-dimethyl-1,2-propanediamine, N-butylethanolamine, N-cyclohexyl-1,3-propanediamine, N-ethylethanolamine, N-methyl(tetrahydro-2-furanyl)methanamine, N-propylethanolamine, tetrahydro-2-furanylmethylamine.

[0037] Advantageously, the absorbent solution comprises 10 to 100% by weight, and preferably between 20 and 70% by weight, of reactive compounds.

[0038] Advantageously, the absorbing solution comprises at least one solvation compound selected from the group consisting of water, glycols, polyethylene glycols, polypropylene glycols, ethylene glycol-propylene glycol copolymers, glycol ethers, alcohols, ureas, lactams, N-alkylated pyrrolidones, N-alkylated piperidones, cyclotetramethylenesulfones, N-alkylformamides, N-alkylacetamides, ether ketones, alkyl phosphates and their derivatives.

[0039] Preferably, the absorbing solution comprises water as the solvation compound and includes one or more reactive compounds from the following list: N,N,N',N',N”-pentamethyldiethylenetriamine, N,N,N',N”,N'-pentamethyldipropylenetriamine, N,N-bis(2,2-diethoxyethyl)methylamine, piperazine, 2-amino-2-methylpropanol, N,N-dimethyldipropylenetriamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 4-hydroxy-N-methylpiperidine, tetrahydroisoquinoline, N-methyldiethanolamine, N,N,N',N'-tetramethyl-1,4-butanediamine, bis(2-(N,N-dimethylamino)propyl)ether, bis(2-(N,N-dimethylamino)ethyl)ether, 1,3-bis(dimethylamino)-2-propanol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethyldiethylenetriamine, 1,2-bis(dimethylaminoethyl)ethane.

[0040] According to one variant of the invention, the absorbing solution comprises a main reactive compound and at least one secondary reactive compound, preferably the main reactive compound representing between 5 and 60% by weight of the absorbing solution and each secondary reactive compound representing between 0.5 and 30%, preferably between 0.5 and 15% and even more preferably between 1 and 10%, by weight of the absorbing solution.

[0041] The invention also relates to a device for deacidifying a gaseous effluent containing acidic compounds, such as hydrogen sulfide or carbon dioxide, to implement the process as described according to one of the variants or combinations of variants, comprising:

[0042] - an absorption column to bring the gaseous effluent into contact with an absorbing solution in order to produce a gas depleted in acidic compounds and an absorbing solution loaded with acidic compounds, the absorbing solution being chosen for its property of forming separable phases when it has absorbed a quantity of acidic compounds and is heated;

[0043] - a transport line for the absorbent solution loaded with acidic compounds going from the absorption column to the regeneration column;

[0044] - a conveying line for an absorbent solution to be recycled from the regeneration column to the absorption column;

[0045] - at least one first heat exchanger and one second heat exchanger to exchange heat between the fluids flowing in the transport line and in the delivery line;

[0046] - the transport line comprising a separation means to separate the absorbent solution loaded with acid compounds into a gaseous fraction, into a first liquid fraction of absorbent solution depleted in acid compounds and into a second liquid fraction of absorbent solution enriched in acid compounds;

[0047] - at least one first bypass line in fluidic connection between the transport line upstream of the first heat exchanger and the regeneration column;

[0048] - at least one second bypass line in fluidic connection between the transport line downstream of the first heat exchanger and the regeneration column; - the regeneration column to release the acid compounds contained at least in said second liquid fraction and / or in at least a portion of the absorbent solution loaded with acid compounds and to produce a regenerated absorbent solution forming part of the absorbent solution to be recycled, said regeneration column preferably being equipped with at least one reboiler to form steam by vaporizing part of the regenerated absorbent solution taken from the regeneration column.

[0049] List of figures

[0050] Other features and advantages of the process and / or device according to the invention will become apparent from the following description of non-limiting examples of embodiment, with reference to the figures attached and described below.

[0051] Figure 1 represents a first example of a device and method for deacidifying a gaseous effluent according to the invention.

[0052] Figure 2 represents a second example of a device and method for deacidifying a gaseous effluent according to the invention.

[0053] Figure 3 represents a third example of a device and method for deacidifying a gaseous effluent according to the invention.

[0054] Figure 4 represents a fourth example of a device and method for deacidifying a gaseous effluent according to the invention.

[0055] Figure 5 represents a fifth example of a device and method for deacidifying a gaseous effluent according to the invention.

[0056] Figure 6 represents a sixth example of a device and method for deacidifying a gaseous effluent according to the invention.

[0057] Description of the implementation methods

[0058] The terms "upstream" and "downstream" are understood in the direction of the flow of the fluid at the location in question, the fluid being the gaseous effluent to be deacidified, the gas exiting the regeneration column, the absorbent solution loaded with acidic compounds, the gaseous fraction, the first liquid fraction, the second liquid fraction, the absorbent solution low in acidic compounds, the absorbent solution to be recycled for example.

[0059] In this description, the term "demixing" refers to the phenomenon of separation into two liquid phases of a single-phase liquid absorbent solution. An absorbent solution is one capable of absorbing acidic compounds from a gaseous effluent, such as CO2, H2S, COS, CS2, SO2, and mercaptans, under appropriate operating conditions (temperature, pressure, and physical elements of gas / liquid contact). The adjectives "demixing" are used in reference to the demixing phenomenon. A demixing absorbent solution is thus one capable of forming two separable liquid phases when it contains a predetermined quantity of acidic compounds.

[0060] The invention relates to a process for deacidifying a gaseous effluent containing acidic compounds, such as hydrogen sulfide (H2S) or carbon dioxide (CO2).

[0061] In this process, at least the following steps are carried out: a) the gaseous effluent is contacted with an absorbent solution in an absorption column, so as to obtain a gaseous effluent depleted in acid compounds and an absorbent solution saturated with acid compounds; b) the absorbent solution saturated with acid compounds is separated in a separation medium into a gaseous fraction, a first liquid fraction depleted in acid compounds, and a second liquid fraction enriched in acid compounds. Thus, in the separation medium, a demixing phenomenon of two liquid fractions is generated, and a gaseous fraction is generated resulting partly from the vaporization of water and partly from the desorption of some of the absorbed acid compounds; c) the absorbent solution saturated with acid compounds and / or the second liquid fraction are heated in at least one first heat exchanger and in at least one second heat exchanger.d) at least a first portion of the absorbent solution loaded with acidic compounds is diverted into a first bypass line upstream of the first heat exchanger and sent to the regeneration column; e) at least a second portion of the absorbent solution loaded with acidic compounds or of the second liquid fraction is diverted into a second bypass line downstream of the first heat exchanger and sent to the regeneration column; f) the first portion of the absorbent solution loaded with acidic compounds (from the first bypass line) and the second portion of the absorbent solution loaded with acidic compounds or of the second liquid fraction (from the second bypass line) are regenerated.and the second liquid fraction (or the remainder of the second liquid fraction) in a regeneration column so as to release the acidic compounds into an outgoing gas stream and thus form an acid-poor absorbent solution exiting the regeneration column, g) an absorbent solution to be recycled is recycled as an absorbent solution in step a), the absorbent solution to be recycled comprising at least the acid-poor absorbent solution regenerated in step f) and preferably the first liquid fraction obtained in step b).,

[0062] Step a) of establishing contact

[0063] In an absorption column, a gaseous effluent (for example, a gas from a combustion process / device) containing acidic compounds, such as CO2 or H2S, is brought into contact with an absorbent solution. The purpose of this contact is to enable the absorbent solution to absorb the acidic compounds, thereby reducing or even eliminating the amount of acidic compounds in the gaseous effluent and releasing at least some (preferably most) of them. In other words, the absorbent solution selectively absorbs the acidic compounds from the gaseous effluent within the absorption column. As a result, the gaseous effluent exits the absorption column depleted of acidic compounds, and the absorbent solution exits the column enriched (or loaded) with acidic compounds.

[0064] In addition, the absorbing solution is chosen in this invention for its property of forming separable phases when it has absorbed a certain amount of acidic compounds and is heated: the absorbing solution therefore has acidic compound absorption and demixing properties related to acidic compounds and temperature.

[0065] Acidic compounds can include acid gases, such as carbon dioxide (CO2) or hydrogen sulfide (H2S). The absorbing solution can be chosen based on factors such as the type of acidic compounds to be absorbed and the temperature.

[0066] The invention also relates to an absorbent solution as defined in this description, according to any of the variants or combinations thereof, for the deacidification of a gaseous effluent containing acidic compounds, for example, for the decarbonation of combustion fumes or the deacidification of natural or industrial gas. The absorbent solution may comprise one or more reactive compounds or compounds having a physicochemical affinity for the acidic compounds and optionally one or more solvation compounds. Preferably, an absorbent solution is chosen that includes compounds reactive with the acidic compounds. The compound(s) possibly used for the solvation of the reactive compound(s) may possess functional groups reactive with the acidic compounds to be treated.

[0067] The absorbing solution may comprise a primary reactive compound and at least one secondary reactive compound.

[0068] The term "main reactive compound" refers to the reactive compound in the absorbing solution that has the highest concentration in the absorbing solution, when the absorbing solution includes several reactive compounds: it is therefore the major reactive compound present in the absorbing solution.

[0069] The term "secondary reactive compound" refers to a reactive compound in the absorbing solution that is different from the main reactive compound: it is therefore a reactive compound that is not the major reactive compound in the absorbing solution.

[0070] According to one configuration of the invention, the reactive compound(s) (in particular the main reactive compound and / or at least one secondary reactive compound) may be selected from the group consisting of amines, alkanolamines, amino acids, alkali salts of amino acids, amides, ureas, phosphates, carbonates and borates of alkali metals.

[0071] Reactive compounds (including main and / or secondary) may include, for example and without limitation, amines (primary, secondary, tertiary, cyclic or non-cyclic, aromatic or non-aromatic, saturated or non-saturated), alkanolamines, polyamines, amino acids, alkali salts of amino acids, amides, ureas, phosphates, carbonates or borates of alkali metals.

[0072] Reactive compounds containing an amine function preferably have the following structure: X represents an amine function (NR 6 ) or an oxygen atom (O) or a sulfur atom (S) or a disulfide (SS) or a carbonyl group (C=O) or a carboxyl group (O=CO) or an amide group (O=CNR 6 ) or an aromatic ring with 6 carbon atoms. n and m are integers, n can take all values ​​from 0 to 8, preferably from 0 to 6, and m all values ​​from 1 to 7, preferably from 1 to 5.

[0073] R 5 represents either a hydrogen atom or a hydrocarbon chain, branched or unbranched, saturated or unsaturated, comprising from 1 to 10 carbon atoms, preferably from 1 to 8 carbon atoms.

[0074] R 1 , R 2 , R 3 , R 4 and R 6 represent either a hydrogen atom, or a hydrocarbon chain, branched or unbranched, saturated or unsaturated, comprising from 1 to 10 carbon atoms, preferably from 1 to 8 carbon atoms, or have the following structure: q and p are integers, q can take all values ​​from 0 to 6, preferably from 0 to 4, and p all values ​​from 0 to 7, preferably from 0 to 5.

[0075] Y represents an amine function (NR 10 ) or an oxygen atom (O) or a sulfur atom (S) or a disulfide (SS) or a carbonyl group (C=O) or a carboxyl group (O=CO) or an amide group (O=CNR 10) or an aromatic nucleus with 6 carbon atoms.

[0076] R 7 , R 8 , R 9 and R 10 represent either a hydrogen atom, or a hydrocarbon chain, branched or unbranched, saturated or unsaturated, comprising from 1 to 10 carbon atoms, preferably from 1 to 8 carbon atoms.

[0077] R 1 , R 2 , R 3 , R 4 , R 5 and R 6 , and possibly R 7 , R 8 , R 9 and R 10 can be defined in such a way as to possibly constitute cycles or heterocycles, saturated or not, aromatic or not, by associating them two by two.

[0078] When X is an aromatic ring with 6 carbon atoms, X and at least one of the R groups 1 , R 2 , R 3 , R 4 , R 5 , R 6 and possibly R 7 , R 8 , R 9 and R 10can be defined in such a way as to possibly constitute cycles or heterocycles, saturated or not, aromatic or not, by associating them two by two.

[0079] When Y is an aromatic ring with 6 carbon atoms, Y and at least one of the R groups 1 , R 2 , R 3 , R 4 , R 5 , R 6 and possibly R 7 , R 8 , R 9 and R 10 can be defined in such a way as to possibly constitute cycles or heterocycles, saturated or not, aromatic or not, by associating them two by two.

[0080] By way of example and without limitation, reactive compounds containing an amine group may be chosen from the following list: monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxy)ethanol, N,N-dimethylaminoethoxyethanol, N,N,N'-trimethyl-N'-hydroxyethyl-bisaminoethyl ether, N,N-bis-(3-dimethylaminopropyl)-N-isopropanolamine, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N,N-dimethylethanolamine, N-(2-aminoethyl)ethanolamine, 3-amino-1-propanol, 3-ethoxypropylamine, N-methylethanolamine, N-methyldiethanolamine, diisopropanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethyl-1 ,3-propanediamine, N,N,N-tris(3-dimethylaminopropyl)amine, N,N,N',N",N'-pentamethyldipropylenetriamine, N,N,N',N'-tetramethyliminobispropylamine, N-(3-aminopropyl)morpholine, N-(2-dimethylaminoethyl)morpholine, 3-methoxypropylamine, N-(2-aminoethyl)piperazine, 2,2-Dimorpholinodiethyl ether, N,N'-dimethylpiperazine, N,N,N',N',N”-pentamethyldiethylenetriamine, N-(3-aminopropyl)piperazine, ethyl 1-piperazine carboxylate, dipropylenetriamine, N,N-Bis(2,2-diethoxyethyl)methylamine, 3-butyl-2-(1-ethylpentyl)oxazolidine, 3-ethyl-2-methyl-2-(3-methylbutyl)oxazolidine, 1,2,2,6,6-pentamethyl-4-piperidone, 1-(2-methylpropyl)-4-piperidone, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetraethyliminobisethylamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, 1 ,1,4,7,10,10-hexamethyltriethylenetetramine, 1-phenylpiperazine, 1-formylpiperazine, ethyl 1-piperazinecarboxylate, N,N'-di-tert-butylethylenediamine, 4-ethyl-2-methyl-2-(3-methylbutyl)oxazolidine, tetraethylenepentamine, triethylenetetramine, N,N-diethyldiethylenetriamine, N1-isopropyldiethylenetriamine, piperazine, N,N-dimethyldipropylenetriamine, diethylenetriamine,N-(2-aminoethyl)-1,3-propanediamine, 2,2'-(ethylenedioxy)diethylamine, 4-hydroxy-N-methylpiperidine, N-(2-aminoethyl)morpholine, 4-amino-2,2,6,6-tetramethylpiperidine, 1,2-diaminocyclohexane, 2-piperidinoethylamine, 2-(2-aminoethyl)-1-methylpyrrolidine, ethylenediamine, N,N-diethylethylenediamine, N-phenylethylenediamine, N-(3-aminopropyl)piperidine, furfurylamine, 2-(aminomethyl)thiophene, 4,9-dioxa-1,12-dodecanediamine, 4,7,10-trioxa-1,13-tridecanediamine, 1,2,4-trimethylpiperazine, 2-amino-2-methylpropanol, N,N'-diethyl-N,N'-dimethylethylenediamine, N,N-diethyl-N',N'-dimethylethylenediamine, 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4-dimethyl-1,4-diazacycloheptane, N-(2-dimethylaminoethyl)-N'-methylpiperazine, N,N,N',N'-tetraethylpropylenediamine, 1-[2-(1-piperidinyl)ethyl)]piperidine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, hexamethylenediamine, 1,2-propanediamine, 2-methyl-1,2-propanediamine, 2-methylpiperazine, N-2,N-2-dimethyl-1,2-propanediamine, N-1,N-1-dimethyl-1,2-propanediamine, 4,4'-ethylenedimorpholine, N,N,N',N'-tetraethyl-N”-methyldipropylenetriamine, 4-(dimethylamino)-1,2,2,6,6-pentamethylpiperidine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 1,5,9-trimethyl-1,5,9-triazacyclododecane, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, N,N'- difurfurylethylenediamine, 1,2-Bis(2-aminoethyl)thioethane, Bis(2-aminoethyl)disulfide, Bis(2-dimethylaminoethyl)sulfide, 2,6-dimethylpiperazine, 1-ethyl-3-piperidinamine, decahydroquinoxaline, 2,3,5,6-tetramethylpiperazine, N,N-dimethyl(2-piperidinyl)methanamine, 1-(2-piperidinylmethyl)piperidine, 1-acetyl-2-diethylaminoethane, 1-amino-2-benzylaminoethane, 1-acetyl-3-dimethylaminopropane, 1-dimethylamino-3,3-diphenylpropane, N,N-dimethylbenzylamine,2-(dimethylaminomethyl)thiophene, N,N,5-trimethylfurfurylamine, N,N-Bis(tetrahydro-2-furanylmethyl)amine, tetrahydroisoquinoline, 2-(ethylsulfanyl)ethanamine, thiomorpholine, 2-[(2-aminoethyl)sulfanyl]ethanol, 2,2-dimethyl-1,3-propanediamine, N1,N3,2-trimethyl-1,3-propanediamine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, N1,N1,2,2-tetramethyl-1,3-propanediamine, 1-methoxy-2-propanamine, 3-thiomorpholinylmethanol, 2-(butylamino)ethanethiol, Bis(2-diethylaminoethyl)ether, the 1-dimethylamino-2-ethylmethylaminoethoxyethane, 1,2,3-triaminopropane and N-1-(2-aminopropyl)-1,2-propanediamine, tetrahydro-2-furanylmethylamine, 2,6-dimethylmorpholine, N-methyl(tetrahydro-2-furanyl)methanamine, N,N,N',N'-tetramethyl-1,4-butanediamine, bis(2-(N,N-dimethylamino)propyl)ether, bis(2-(N,N-dimethylamino)ethyl)ether, 1,3-bis(dimethylamino)-2-propanol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethyldiethylenetriamine, 1,2-bis(dimethylaminoethyl)ethane, 1-(2-piperidinylmethyl)piperidine, 1,2,3-triaminopropane, 1,2-propanediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1-ethyl-3-piperidinamine, 1-methoxy-2-propanamine, 2-(2-aminoethoxy)ethanol, 2-(aminomethyl)-2-methyl-1,3-propanediamine, 2-(aminomethyl)thiophene, 2,2-dimethyl-1,3-propanediamine, 2,3,5,6-tetramethylpiperazine, 2,6-dimethylmorpholine, 2,6-dimethylpiperazine, 2-methyl-1,2-propanediamine, 2-methylpiperazine, 3-amino-1-propanol, 3-ethoxypropylamine, bis(aminoethyl)sulfur, decahydroquinoxaline, dipropylenetriamine, furfurylamine, hexamethylenediamine, N-(2-aminoethyl)ethanolamine, N-(2-aminoethyl)piperidine, N-(3-aminopropyl)piperazine, N-(3-aminopropyl)piperidine, N,N-dimethyl(2-piperidinyl)methanamine, N-1-(2-aminopropyl)-1,2-propanediamine, N-1,N-1,22-tetramethyl-1,3-propanediamine, N-1,N-1-dimethyl-1,2-propanediamine, N-1,N-3,2-trimethyl-1,3-propanediamine, N-2,N-2-dimethyl-1,2-propanediamine, N-butylethanolamine, N-cyclohexyl-1,3-propanediamine, N-ethylethanolamine, N-methyl(tetrahydro-2-furanyl)methanamine, N-propylethanolamine, tetrahydro-2-furanylmethylamine.

[0081] The reactive compounds can represent from 10 to 100% by weight of the absorbing solution, preferably from 20 to 70% by weight of the absorbing solution.

[0082] When the absorbing solution comprises a primary reactive compound and at least one secondary reactive compound: the primary reactive compound may represent between 5 and 60% by weight of the absorbing solution; and / or each of the secondary reactive compounds may represent between 0.5 and 30% by weight of the absorbing solution, preferably between 0.5 and 15% by weight of the absorbing solution and even more preferably between 1 and 10% by weight of the absorbing solution.

[0083] Solvation compounds can be any compounds that dissolve in sufficient quantity the reactive compounds or that are miscible with the reactive compounds described above and that cause the formation of two phases, for example liquid-liquid or liquid-solid, when associated with at least one of the reactive compounds having reacted with one or more acidic compounds, for example H2S, or CO2, or SO2, or mercaptans, or COS or CS2.

[0084] In addition, the absorbing solution may include a solvation compound selected from the group consisting of water, glycols, polyethylene glycols, polypropylene glycols, ethylene glycol-propylene glycol copolymers, glycol ethers, alcohols, ureas, lactams, N-alkylated pyrrolidones, N-alkylated piperidones, cyclotetramethylenesulfones, N-alkylformamides, N-alkylacetamides, ether ketones, alkyl phosphates and their derivatives.

[0085] By way of example and without limitation, it may be water, tetraethyleneglycoldimethyl ether, sulfolane, N-methylpyrrolidone, propylene carbonate, dimethylpropyleneurea, N-methylcaprolactam, dimethylformamide, dimethylacetamide, formamide, acetamide, 2-methoxy-2-methyl-3-butanone, 2-methoxy-2-methyl-4-pentanone, or tributylphosphate.Preferably, an absorbent solution comprising water as the solvation compound and containing one or more reactive compounds from the following list may be used: N,N,N',N',N”-pentamethyldiethylenetriamine, N,N,N',N”,N'-pentamethyldipropylenetriamine, N,N-bis(2,2-diethoxyethyl)methylamine, piperazine, 2-amino-2-methylpropanol, N,N-dimethyldipropylenetriamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 4-hydroxy-N-methylpiperidine, tetrahydroisoquinoline, N-methyldiethanolamine, N,N,N',N'-tetramethyl-1,4-butanediamine, bis(2-(N,N-dimethylamino)propyl)ether, bis(2-(N,N-dimethylamino)ethyl)ether, 1,3-bis(dimethylamino)-2-propanol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethyldiethylenetriamine, 1,2-bis(dimethylaminoethyl)ethane.

[0086] The absorbing solution may also contain one or more salts to lower the partial pressure of acid gases at which a second phase forms through the reaction of the acid gases with the reactive compound(s). These salts may be, for example, but not limited to, salts of alkali metals, alkaline earths, metals, or amines. The associated anion may be, for example, but not limited to, a halide, phosphate, sulfate, nitrate, nitrite, phosphite, or the conjugate base of a carboxylic acid. The amine(s) used to make these salts may be one or more of the amines present in the absorbing solution as reactants with the acidic compounds, or as activators, and which are partially neutralized by one or more acids stronger than those present in the treated gaseous effluent.The acids used may include, but are not limited to, phosphoric acid, phosphorous acid, nitrous acid, oxalic acid, acetic acid, formic acid, propanoic acid, butanoic acid, nitric acid, sulfuric acid, or hydrochloric acid. Other types of amines that are completely neutralized by such acids may also be added to the absorbing solution. These salts may also result from the partial degradation of the absorbing solution, for example, following the reaction of reactive compounds with an impurity in the treated gas. Salts may also be obtained by introducing sodium hydroxide or potassium hydroxide to neutralize acids formed in the process unit. Furthermore, the addition of salts may be avoided in cases where the activators, reactive compounds, or any other additives are salts in nature.The salt concentration can be adapted according to the partial pressure and the nature of the acidic compound(s) present in the gaseous charge to be treated, as well as the implementation conditions.

[0087] The absorbent solution may also contain anti-corrosion and / or anti-foaming additives.

[0088] Their nature and concentration are chosen according to the nature of the absorption solvent used, the load to be treated, and the implementation conditions. Their concentration in the absorbent solution typically varies between 0.01% and 5% by weight. These agents can be vanadium oxides (e.g., V₂O₃) or chromates (e.g., K₂Cr₂O₇).

[0089] The composition of the absorbent solution is determined in particular according to the nature of the gaseous effluent to be treated and the conditions of implementation of the deacidification process.

[0090] Naturally, the absorbing solution entering the absorption column contains no acidic compounds or has a very low concentration of acidic compounds (meaning that it arrives with a much lower concentration of acidic compounds than it leaves). Therefore, at the outlet of the absorption column, the absorbing solution, which is charged with acidic compounds, is enriched in acidic compounds (compared to when it entered the absorption column).

[0091] Step b) of phase separation

[0092] During this step, the different phases generated by the absorbent solution loaded with acidic compounds are separated, due to the unmixing nature of the chosen absorbent solution. These different phases include, in particular:

[0093] - a gaseous fraction generated by some of the acidic compounds released (due to temperature) and possibly water vapor;

[0094] - a first liquid fraction depleted in acidic compounds; a second liquid fraction enriched in acidic compounds.

[0095] The terms "depleted" and "enriched" are understood in relation to each other: in other words, the first liquid fraction is less rich in acidic compounds than the second liquid fraction.

[0096] The first liquid fraction is usually an organic phase, while the second liquid fraction is an aqueous phase.

[0097] Thus, in the separation process, a demixing phenomenon is generated between two liquid fractions, which are also separated from a generated gaseous fraction. The separation device in which this separation takes place can be, for example, a decanter. Various decanter technologies can be used: it could be a gravity or electrostatic decanter, for example, but this list is not exhaustive.

[0098] Subsequently, the portion of the solution between the absorption column and the separation unit is referred to as the "acid-laden solution." Downstream of the separation unit, it is referred to as the "gaseous fraction," the "first liquid fraction," or the "second liquid fraction," all of which are fractions of the acid-laden solution.

[0099] Preferably, the separation means can be positioned between the first and second heat exchangers or between the second heat exchanger and the regeneration column.

[0100] When positioned between the first and second heat exchangers, the first heat exchanger heats the absorbent solution loaded with acidic compounds, and the second heat exchanger heats the second liquid fraction.

[0101] When positioned between the second heat exchanger and the regeneration column, both the first and second heat exchangers reheat the absorbent solution loaded with acidic compounds. This configuration further reduces the flow rate of the second liquid fraction to the regeneration column.

[0102] Step c) of reheating

[0103] Step c) consists of heating at least a portion of the solution loaded with acid compounds, before its demixing (the separation of these phases), or of the second liquid fraction, when the demixing has taken place, in at least two heat exchangers which exchange heat with the absorbing solution to be recycled (i.e. the solution which re-enters the absorption column, as will be explained later).

[0104] Thus, the absorbent solution containing acidic compounds can be heated in at least one first heat exchanger and preferably in a second. Therefore, on the transport line (also called the "rich" line) that runs from the absorption column to the regeneration column in the direction of fluid flow in that line, the first heat exchanger is upstream (in the direction of flow in the transport line) of the separation unit. Alternatively, the absorbent solution containing acidic compounds can be heated in at least one first heat exchanger, and the second liquid fraction can be heated in a second heat exchanger. It follows that the second heat exchanger is downstream of the first heat exchanger in the direction of flow of the absorbent solution from the absorption column to the regeneration column.Given the reverse flow direction of the absorbing solution from the regeneration column to the absorption column, the second heat exchanger is upstream of the first heat exchanger in this direction of flow.

[0105] The use of at least two heat exchangers improves the thermal performance of the process. These exchangers promote the demixing phenomenon on the one hand and facilitate the release of acidic compounds in the regeneration column on the other.

[0106] According to one embodiment of the invention, the absorbent solution loaded with acidic compounds can be heated in an additional heating means, upstream or downstream of the separation means. When positioned upstream of the separation means, this additional heating means allows temperature control to promote demixing within the separation means in order to better control the separation (for example, decantation).

[0107] According to a first variant of this implementation, the additional heating means can be positioned directly upstream of the separation means (i.e., there is no other equipment between the additional heating means and the separation means), preferably between the first heat exchanger and the separation means. As a result, the temperature is even better controlled to promote demixing.

[0108] According to a second variant of this implementation, when the additional heating means is positioned downstream of the separation means, it can be positioned:

[0109] - either between the separation means and the second heat exchanger, for example between the separation means and the connection of the transmission line to the second branch line, or between the connection of the transmission line to the second branch line and the second heat exchanger.

[0110] - either between the second heat exchanger and the regeneration column, upstream or downstream of the connection of the transmission line to a branch line, when a branch line is positioned on the portion located between the second heat exchanger and the regeneration column.

[0111] This additional heating can be used to improve temperature control in the second bypass line, the possible third bypass line, in the second heat exchanger or the temperature of the fluid entering the regeneration column (from the transport line and / or bypass lines).

[0112] The choice of location for the additional heating element, particularly for the second variant, may depend on the fluid temperature in the various lines (bypass, transport), the fluid characteristics, and the operating conditions, in order to improve the overall process performance. This choice can therefore be determined based on numerical simulations or experimental tests.

[0113] This additional heating method can be an electric heater or a heat exchanger using, for example, any hot utility (from the site of the process or device) or any other heat source, such as an OSBL thermal integration for "Outside Battery Limits" meaning an energy source outside the process or system.

[0114] Advantageously, the temperature of the additional heating means can be controlled so as to control the temperature of the absorbing solution loaded with acidic compounds in the separation means.

[0115] According to one embodiment of the invention, in step c), the acid-rich absorbent solution can be heated in said first heat exchanger and in an intermediate heat exchanger, and the second liquid fraction is heated in said second heat exchanger, said intermediate heat exchanger exchanging heat with the absorbent solution to be recycled. This further improves the thermal integration of the process. Thus, in this embodiment, the invention uses at least three heat exchangers that exchange heat between the solution to be recycled (from the regeneration column to the absorption column) and the acid-rich absorbent solution (or the second fraction) from the absorption column to the regeneration column.

[0116] Step d) of branching into a first branch line

[0117] Upstream of the first heat exchanger (in the direction of flow of the absorbing solution from the absorption column to the regeneration column, i.e., in the transport line from the absorption column to the regeneration column), at least a first portion of the absorbing solution, rich in acidic compounds, is diverted into a first bypass line. This first bypass line originates upstream of the first heat exchanger (in the direction of fluid flow in the transport line) and terminates at the regeneration column. Since, on the transport line (also called the "rich" line), the first heat exchanger is upstream (in the direction of flow in the transport line) of the separation unit, the first bypass line is upstream of the separation unit on the transport line (in the direction of flow in that line).

[0118] Subsequently, the term "first portion" refers to the portion of fluid from the transport line passing through the first bypass line. The first portion is therefore a portion of the absorbing solution containing acidic compounds.

[0119] This first bypass line, leading into the regeneration column, allows the absorption fluid, loaded with acidic compounds, to be used to cool the gas stream before it exits the regeneration column. Simultaneously, it heats the fluid arriving from this first bypass line—that is, the first section—to facilitate the release of the acidic compounds. By cooling the gas stream as it prepares to exit the regeneration column through this first section, the power required by the condenser can be reduced, thus limiting energy consumption.

[0120] The first bypass line is made possible in particular by the fact that the absorbing solution loaded with acidic compounds heats up less quickly than the regenerated absorbing solution (discharged of acidic compounds) cools down.

[0121] According to one configuration of the invention, the first portion can be heated by direct heat exchange within the regeneration column. This allows for a more economical and thermally efficient operation. This configuration is more thermally efficient than the solution where heat exchange occurs indirectly. Furthermore, this solution eliminates the need for a heat exchanger.

[0122] Alternatively or additionally, the first portion can be heated indirectly with the gas stream exiting the regeneration column. This facilitates the release of the acidic compounds contained in the first portion and cools the gas stream (thus resulting in a more economical and thermally efficient operation). This solution avoids the risk of reabsorbing a fraction of the acidic compounds that were desorbed in the regeneration column.

[0123] Step e) of branching into a second branch line

[0124] Downstream of the first heat exchanger (in the direction of flow of the absorbing solution in the transport line from the absorption column to the regeneration column), at least a second portion, either of the absorbing solution loaded with acidic compounds or of the second liquid fraction, is diverted into a second bypass line. This second bypass line originates downstream of the first heat exchanger (in the direction of flow in the transport line) and terminates at the regeneration column.

[0125] Subsequently, the term "second portion" refers to the portion of fluid from the transport line that passes into the second bypass line. The second portion is therefore either a portion of the absorbing solution laden with acidic compounds or a portion of the second liquid fraction, depending on the location of the second bypass line's origin on the transport line.

[0126] The use of a demixing absorbent solution allows for a greater quantity of vaporized fluid in the second heat exchanger, at the same temperature, compared to a non-demixing absorbent solution. This greater vaporization allows for a higher flow rate in the second bypass line than with a non-demixing absorbent solution such as those used in US patent 9,956,505 B2 or US patent application 2010 / 0,242,731 A1. This higher flow rate improves the cooling of the gas stream in the generation column and thus enhances the energy efficiency of the process.

[0127] This second bypass line leading into the regeneration column allows the fluid from the absorbing solution loaded with acidic compounds to be used to cool the gas stream before it exits the regeneration column and in parallel to heat the fluid arriving from this second bypass line, i.e. the said second portion, in order to facilitate the release of the acidic compounds.

[0128] The second bypass line, like the first, is made possible by the fact that the absorbent solution loaded with acid compounds heats up more slowly than the regenerated absorbent solution (free of acid compounds) cools down. However, this second bypass line is positioned after the first heat exchanger. Consequently, the fluid temperature in this second bypass line is higher than that in the first bypass line (and than that in the transport line from the absorption column to the regeneration column, upstream of the bypass lines). Preferably, the temperature between the two heat exchangers corresponds to the bubble temperature of the absorbent solution loaded with acid compounds, the temperature at which the absorbent solution vaporizes at the operating pressure in the second heat exchanger.This vaporization, which is much more pronounced with a demixing absorbent solution according to the invention, allows a flow rate of the second bypass line much higher than that of the first bypass line and higher than that of the prior art which does not use a demixing absorbent solution.

[0129] Furthermore, it is worth noting that this improvement in the thermal performance of the process with two bypass lines and a demixing absorbent solution is counterintuitive and occurs in a surprising manner. Indeed, as indicated in patent application EP1656983 A1 in particular, demixing absorbent solutions are used to limit the amount of solution sent to the regeneration column and thus limit the amount of solution to be regenerated. The aim is therefore to send only the liquid phase, known as the "second liquid fraction," rich in acidic compounds, to the regeneration column. It is therefore counterintuitive, given this knowledge, to send a portion of the solution loaded with acidic compounds, before demixing, directly to the regeneration column (in the first and / or second lines) to improve thermal performance.Furthermore, this absorbent solution, laden with acidic compounds, is relatively "cold" since it is diverted before passing through the first or second heat exchanger, and it needs to be reheated in the regeneration column to remove the acidic compounds. Indeed, sending an additional quantity of this charged, unmixed, and relatively cold absorbent solution into the regeneration column could lead to a degradation in overall thermal performance, due to the increased volume of solution requiring regeneration.

[0130] The temperature of the second section is higher than that of the first section because the fluid has at least passed through the first heat exchanger where it was heated. This higher temperature can lead to gradual vaporization of the fluid. Consequently, the flow rate in the second bypass line may be higher than the flow rate in the first bypass line.

[0131] Preferably, the flow in the first bypass line and / or in the second bypass line can be controlled by manual or automatic flow control means, preferably flow control valves, so as to allow or not the flow in these lines, depending on the operating situation and the characteristics of the process.

[0132] When the invention includes an intermediate heat exchanger for heating the absorbing solution loaded with acid compounds (the second heat exchanger then serving to heat the second liquid fraction), the second portion of the absorbing solution loaded with acid compounds can be diverted in the second bypass line between the first heat exchanger and the intermediate heat exchanger, and a third portion of the second liquid fraction can be diverted in a third bypass line between the separation means and the second heat exchanger, the third portion being sent to the regeneration column to be regenerated, i.e., freed from its acid compounds.

[0133] Subsequently, the so-called "third portion" refers to the portion of fluid from the transport line passing through the third bypass line. The third portion is therefore a portion of the second liquid fraction.

[0134] In the regeneration column, the third portion can, for example, be injected at an altitude (level or height) located between the injection altitude (level or height) of the second portion and the injection altitude (level or height) of the second liquid fraction. This position allows the third portion to be injected into the regeneration column at a level where the temperature is very close to that of the third portion, thus improving thermal performance.

[0135] Preferably, the flow in the third bypass line can be controlled by manual or automatic flow control systems, preferably flow control valves, so as to allow or not allow flow in this line, depending on the operating situation and the characteristics of the process.

[0136] Step f) of regeneration of the absorbent solution

[0137] In the regeneration column, acidic compounds are released from the various portions and fractions of absorbing solutions that are sent there. Indeed, due to the separation of the different phases and the bypass lines, several portions or fractions of absorbing solution, initially loaded with acidic compounds, leaving the absorption column, are sent to the regeneration column.

[0138] The following is found at the outlet of the regeneration column:

[0139] - a gas stream rich in acidic compounds (and generally also containing water vapor). Acidic gases such as CO2 can then be stored or reused, or converted; for example, H2S can be converted into elemental sulfur or sulfur adsorbed onto solids. The absorbing solution is depleted of acidic compounds (these having been released in the regeneration column).

[0140] This depleted absorbent solution (also called "low in acid compounds") can then be used as an absorbent solution for recycling. This depleted absorbent solution is relatively hot (compared to the enriched absorbent solution) after passing through the regenerator where it has been heated. It is then sent to the absorption column, passing successively through at least the second heat exchanger, possibly the intermediate heat exchanger, and then through at least the first heat exchanger, where it transfers its heat to the acid-rich solution and / or the second liquid fraction, particularly in the second heat exchanger.

[0141] The different fractions / portions of absorbing solution arriving in the regeneration column to release acidic compounds are at least the following:

[0142] - the second liquid fraction (or at least the portion of this liquid fraction that is not sent to the second bypass line or to the third bypass line);

[0143] - the first portion of the absorbing solution loaded with acidic compounds;

[0144] - the second portion which can be either the absorbing solution loaded with acidic compounds (upstream of the separation means in the transport line), or the second liquid fraction (downstream of the separation means in the transport line); optionally the third portion.

[0145] Advantageously, the second liquid fraction can be heated by a heater just before being injected into the regeneration column. The heat supplied by the heater can be of any type: fluid, electrical, etc. Heating the second liquid fraction just before the regeneration column facilitates the release of acidic compounds into the regeneration column.

[0146] Preferably, at least a portion, and preferably all, of the acid-poor absorbent solution exiting the regeneration column can be taken and passed through a reboiler to generate steam. This steam is then injected into the regeneration column to provide heat. The reboiler thus facilitates the heating of the regeneration column while minimizing energy consumption. This results in high-quality and more thorough regeneration than processes without a reboiler, such as those shown in Figures 1 and 2 of US Patent 9,956,505 B2. Extensive regeneration is advantageous for demixing absorbent solutions like those used in the invention.

[0147] Preferably, the water vapor contained in the gas stream exiting the regeneration column can be condensed in a condenser, and the condensed water can be discharged from the condenser. By removing the water from the gas stream, the gas can be stored more easily, and furthermore, the degradation of the equipment used for compressing or storing the gas stream, which could be caused by the presence of liquid water, is avoided. By recycling the water, the water loss from the process can be limited. Indeed, a neutral or slightly negative water balance can be sought to avoid the production of aqueous effluent, which would require additional treatment.

[0148] According to one embodiment of the invention, at least a portion of the condensed water discharged from the condenser can be reinjected into the upper part of the regeneration column. This helps to limit the mechanical entrainment of the absorbent solution in the outgoing gas stream by reducing reflux. Furthermore, the water saturated with acidic compounds improves the scrubbing of the hot gas stream exiting the regeneration column.

[0149] Alternatively or additionally, at least some of the condensate discharged from the condenser can be mixed with the absorbent solution containing acidic compounds in the transport line between the absorption column and the first heat exchanger. This saves on the one hand a pump and increases the flow rate of the first section of the first bypass line.

[0150] According to one embodiment of the invention, the gaseous fraction exiting the separation means can be injected into the regeneration column. This allows the cooling section to be shared, as the gaseous fraction then exits the regeneration column with the outgoing gas stream. Furthermore, this gaseous fraction helps to preheat the fluid arriving from the first bypass line (arriving via an injection into the regeneration column, preferably above the injection point of the gaseous fraction into the regeneration column, in the operating position).

[0151] According to one embodiment of the invention, the first portion and the second portion can be mixed before entering the regeneration column, and the mixture of the first and second portions can be injected at a first altitude (level or height) located above a second altitude (level or height) where the second liquid fraction is injected into the regeneration column. This is because the temperature of the second liquid fraction is higher than the temperatures of the first and second portions. Therefore, it is preferable to inject the second liquid fraction into the regeneration column at an altitude (level or height) lower than the combined injection point of the first and second portions to optimize the thermal performance of the process.

[0152] Alternatively, in the regeneration column, the first portion can be injected at a higher altitude (level or height) than the second portion, which is itself higher than the second liquid fraction. Preferably, the gaseous fraction can be injected between the injection altitude (level or height) of the first portion and the injection altitude (level or height) of the second portion. This is because the temperature of the second liquid fraction is higher than the temperature of the second portion, which is itself higher than the temperature of the first portion. Therefore, it is preferable to inject the second liquid fraction into the regeneration column at a lower altitude (level or height) than the injection of the second portion, which is itself lower than the injection of the first portion, to optimize the thermal performance of the process.Furthermore, injecting the gaseous fraction between the injections of the first and second portions helps to promote heat transfer between the first portion and the gaseous fraction, thus limiting the energy consumption of the condenser.

[0153] Step g) of recycling the absorbent solution

[0154] In this step, the regenerated absorbent solution is recycled from the regeneration column along with the first liquid fraction. Thus, the absorbent solution to be recycled comprises:

[0155] - the absorbent solution exiting the regeneration column (depleted / poor in acidic compounds);

[0156] - and the first liquid fraction obtained in step b).

[0157] The absorbent solution to be recycled, therefore entering the absorption column, preferentially comprises these two streams.

[0158] The connection between the regenerated absorbent solution exiting the regeneration column and the first liquid fraction obtained in step b) is made upstream of the first and second heat exchangers in the conveying line. Thus, the absorbent solution to be recycled (which includes both the regenerated absorbent solution and the first liquid fraction) is used in the second heat exchanger, and then in the first heat exchanger in the conveying line (which runs from the regeneration column to the absorption column), in the direction of fluid flow in that line. Advantageously, the gaseous fraction can be compressed in a compression device (such as a compressor) between the separation device and the regeneration column. Consequently, the heat released by compression can be used to reduce the energy consumption of the process, and in particular that of the reboiler.Alternatively, the gaseous fraction can be expanded in an expansion means (such as a turbine) between the separation means and the regeneration column.

[0159] The process can advantageously be implemented in pressure ranges of the separation means and / or the regeneration column between 1 and 10 bar absolute, preferably from 2 to 6 bar absolute.

[0160] The invention also relates to a device for deacidifying a gaseous effluent containing acidic compounds, such as hydrogen sulfide or carbon dioxide, for implementing the process according to one of the variants or combinations of variants described above, comprising:

[0161] - an absorption column to bring the gaseous effluent into contact with an absorbing solution in order to produce a gas depleted in acidic compounds and an absorbing solution loaded with acidic compounds, the absorbing solution being chosen for its property of forming separable phases when it has absorbed a quantity of acidic compounds and is heated;

[0162] - a transport line for the absorbent solution loaded with acidic compounds going from the absorption column to the regeneration column (in the direction of fluid flow in this line);

[0163] - a conveying line for an absorbent solution to be recycled going from the regeneration column to the absorption column (in the direction of fluid flow in this line);

[0164] - at least one first heat exchanger and one second heat exchanger to exchange heat between the fluids flowing in the transport line and in the delivery line;

[0165] - the transport line comprising a separation means to separate the absorbent solution loaded with acid compounds into a gaseous fraction, into a first liquid fraction of absorbent solution depleted in acid compounds and into a second liquid fraction of absorbent solution enriched in acid compounds;

[0166] - at least one first branch line connected to the transport line upstream of the first heat exchanger in the direction of fluid flow in the transport line and leading to the regeneration column;

[0167] - at least one second branch line to the transport line downstream of the first heat exchanger in the direction of fluid flow in the transport line and leading to the regeneration column;

[0168] - a regeneration column to release the acid compounds contained at least in said second liquid fraction and / or in at least a portion of the absorbent solution loaded with acid compounds and to produce a regenerated absorbent solution constituting the absorbent solution to be recycled, said regeneration column preferably being equipped with at least one reboiler to form steam by vaporizing a portion of the regenerated absorbent solution taken from the regeneration column.

[0169] Figures 1 to 6 show schematic and non-limiting examples of embodiments of the process and device for acidifying a gaseous effluent comprising acidic compounds according to the invention.

[0170] In Figure 1, according to a first schematic and non-limiting embodiment of the process and device for deacidifying a gaseous effluent according to the invention, a gaseous effluent EF comprising acidic compounds, such as CO2 or H2S, for example, is brought into contact with a recyclable absorbent solution SAR in an absorption column C101. This absorbent solution has the property of being demixing depending on the quantity and type of acidic compounds it has absorbed and depending on the temperature. Under the effect of the acidic compounds and the temperature, it has the ability to split into two separable liquid phases by a demixing phenomenon, as well as into a gaseous fraction (releasing some of the acidic compounds it has previously absorbed).

[0171] The acidic compounds of the gaseous effluent EF are absorbed and the gaseous effluent exits deacidified EFS from the absorption column C101.

[0172] The absorbing solution loaded with acidic compounds SA exits the absorption column C101 via a transport line which carries the solution in question to the regeneration column C102 to be regenerated.

[0173] This transport line includes a pump P102 to facilitate fluid circulation, at least one first heat exchanger E101 A and a second heat exchanger E101 B, as well as a separation means, in this case a decanter V101. The transport line also includes an optional heat exchanger E105. The absorbent solution, loaded with acidic compounds, is heated in the first heat exchanger E101 A (using the heat from the regenerated absorbent solution SR exiting the regeneration column C102 and the first liquid fraction FL1). It is optionally heated by heat exchanger E105 to control its outlet temperature. It is then sent to decanter V101 where it is split into three streams:

[0174] - a first gaseous fraction FG which is sent to the regeneration column,

[0175] - a first liquid fraction FL1, depleted in acidic compounds and consisting mainly of an organic phase, which is sent to the conveying line that returns the regenerated absorbing solution SR from the regeneration column C102 to the absorption column C101. The first liquid fraction FL1 is thus mixed with the regenerated solution before this mixture, called

[0176] The "absorbent solution to be recycled" does not reach the absorption column C101. An optional P105 pump can be used to facilitate the circulation of the first liquid fraction.

[0177] - a second liquid fraction FL2 enriched in acidic compounds which is sent, preferably with the pump P104, to the second heat exchanger E101 B where it is heated by indirect heat exchange with the regenerated absorbing solution SR exiting the regeneration column C102.

[0178] The absorbent solution introduced into the regeneration column C102 is freed of these acidic compounds by the heat supplied to the column, for example, by the reboiler E104, which takes at least part, preferably all, of the absorbent solution from the lower part of the regeneration column C102, heats it, and generates steam, which is then introduced into the regeneration column C102. This heat allows the desorption of the acidic compounds. The regenerated absorbent solution SR, i.e., free of acidic compounds, exits the regeneration column C102 and is conveyed by a conveying line from the regeneration column C102 to the absorption column C101.In this conveying line, the absorbing solution passes through the second heat exchanger E101 B to heat the second liquid fraction FL2, is mixed with the first liquid fraction FL1, and then this SAR fluid passes through the first heat exchanger E101 A to heat the absorbing solution loaded with acid compounds SA. Optionally, it can pass through another exchanger E103 to further lower its temperature before entering the absorption column C101.

[0179] The process and device also include a first bypass line D1 to divert a first portion of the absorbent solution loaded with acidic compounds SA, before it passes through the first heat exchanger E101 A. This bypass line D1 is called the "cold bypass". The fluid is then sent directly from here to the regeneration column C102.

[0180] The process and apparatus also include a second bypass line D2 for diverting a second portion of the absorbent solution, in this case from the second liquid fraction FL2 obtained from the absorbent solution loaded with acidic compounds SA, after its separation in the decanter V101 and after passing through the first heat exchanger E101A. This second bypass line D2 is called the "hot bypass." The fluid is then sent directly to the regeneration column C102.

[0181] The gas stream exiting the upper part of the regeneration column C102 is sent to a condenser E102 for cooling, then to a separator V102 where the condensed water exits the separator V102 and is sent, preferably by means of a pump P103, to the top of the regeneration column C102. The acid gas GA, consisting mainly of acidic compounds, exits through another outlet of the separator V102. It can then be conditioned for storage or reuse, for example.In Figure 1, the injection of the first portion, arriving from the first bypass line D1, reaches the upper part of the regeneration column C102, above the injection of the gaseous fraction FG into the regeneration column C102. This second portion, in turn, arrives above the injection of the second portion, arriving from the second bypass line D2. D2, in turn, arrives above the injection of the second liquid fraction (i.e., here, the remainder of the second liquid fraction, since a portion of it is taken from the second portion for the second bypass line D2) arriving from the transport line. The terms "above" and "below" refer, of course, to the operating position of the regeneration column, whose axis is essentially vertical when in use.

[0182] Figure 2 shows a second embodiment of the process and device for deacidifying a gaseous effluent according to the invention. In this figure, the reference numerals identical to those in Figure 1 correspond to the same elements and will not be described in detail again.

[0183] Figure 2 differs from Figure 1 in that:

[0184] - on the one hand, the first portion of the first bypass line D1, passes through a heat exchanger E102A to cool the gas flow exiting the regeneration column;

[0185] - on the other hand, the first portion exiting the heat exchanger E102A is mixed with the second portion, from the second bypass line D2, before this mixture is introduced into the regeneration column.

[0186] Given the mixing of the first portion and the second portion before their injection into the regeneration column C102, the position of this injection is located vertically between the injection position of the gaseous fraction FG and that of the second liquid fraction FL2 (more precisely of the remainder of the second liquid fraction since part of this liquid fraction is taken from the second portion of the second bypass line D2).

[0187] Figure 3 shows a third embodiment of the process and device for deacidifying a gaseous effluent according to the invention. In this figure, reference numerals identical to those in Figures 1 or 2 correspond to the same elements and will not be described in detail again.

[0188] Figure 3 differs from Figure 1 in that the water condensed in condenser E102 is reinjected into the transport line, between absorption column C101 and first heat exchanger E101A.

[0189] Figure 4 shows a fourth embodiment of the process and device for the deacidification of a gaseous effluent according to the invention. In this figure, reference numerals identical to those in Figures 1, 2, or 3 correspond to the same elements and will not be described in detail again.

[0190] Figure 4 differs from figure 1 in the following explicit ways.

[0191] The absorbent solution loaded with acid compounds SA, possibly circulated by pump P102, passes into the first heat exchanger where it is heated by the absorbent solution to be recycled, as in Figure 1. Then, the absorbent solution loaded with acid compounds passes into the second heat exchanger E101 B where it is heated by the absorbent solution to be recycled before entering the decanter V101 (as shown in the figure; optionally, another exchanger E105 can be positioned between the second heat exchanger E101 B and the decanter V101), whereas in Figure 1, the absorbent solution loaded with acid compounds SA first passed through the decanter, split into three streams, and only the second liquid fraction passed through the second heat exchanger.

[0192] Furthermore, the second portion of the second bypass line D2 is drawn from between the first heat exchanger E101 A and the second heat exchanger E101 B and is sent directly to the regeneration column C102 at an altitude between the injection altitude of the gaseous fraction FG and the injection altitude of the second liquid fraction FL2. The injection altitude of the first portion of the first bypass line D1 is located above the injection altitude of the gaseous fraction FG, which is itself above the altitude of the second portion.

[0193] On the conveying line bringing the absorbing solution from the regeneration column C102 to the absorption column C101, the first liquid fraction FL1 is first injected and mixed with the regenerated absorbing solution SR coming out of the regeneration column C102, then this solution, called the "solution to be recycled" SAR, is passed through the second heat exchanger E101 B then through the first heat exchanger E101A and possibly through another exchanger E103 to further cool the solution, before it enters the absorption column C101.

[0194] Figure 5 shows a fifth embodiment of the process and device for deacidifying a gaseous effluent according to the invention. In this figure, reference numerals identical to those in Figures 1, 2, 3, or 4 correspond to the same elements and will not be described in detail again.

[0195] Figure 5 differs from figure 1 in the following explicit ways.

[0196] Firstly, the injection altitude of the gaseous fraction FG is positioned here below the injection altitude of the second portion of the second bypass line D2, itself below the injection altitude of the first portion of the first bypass line D1.

[0197] The absorbent solution loaded with acid compounds SA, possibly circulated by pump P102, passes into the first heat exchanger E101 A where it is heated by the absorbent solution to be recycled, as in Figure 1. Then, the absorbent solution loaded with acid compounds passes into the intermediate heat exchanger E101 C where it is heated by the absorbent solution to be recycled before entering the decanter V101 (as shown in the figure, optionally, another exchanger E105 can be positioned between the intermediate heat exchanger E101 C and the decanter V101).

[0198] Furthermore, the second portion of the second bypass line D2 is taken between the first heat exchanger E101 A and the intermediate heat exchanger E101 C and is sent directly into the regeneration column C102.

[0199] Furthermore, between the separation means, here the decanter V101, and the regeneration column C102, the second liquid fraction FL2 passes through the second heat exchanger E101 B which heats it by indirect heat exchange with the regenerated absorbing solution SR exiting the regeneration column C102.

[0200] The process and device also include a third bypass line D3 which originates between the decanter V101 and the second heat exchanger E101 B to bring a third portion of the second liquid fraction FL2 to the regeneration column C102, at an altitude where the remainder of the second liquid fraction FL2 is injected into the regeneration column C102.

[0201] On the conveying line bringing the absorbing solution from the regeneration column C102 to the absorption column C101, the regenerated absorbing solution SR exiting the regeneration column C102 first passes through the second heat exchanger E101 B, then it is mixed with the first liquid fraction FL1. This solution, called the "recycling solution" SAR, is then passed through the intermediate heat exchanger E101 C, then through the first heat exchanger E101A, and possibly through another exchanger E103 to further cool the solution, before it enters the absorption column C101.

[0202] Figure 6 is a sixth embodiment of the process and device for the deacidification of a gaseous effluent according to the invention. In this figure, reference numerals identical to those in Figures 1, 2, 3, 4, or 5 correspond to the same elements and will not be described in detail again.

[0203] Figure 6 differs from Figure 1 in that the gaseous fraction exiting the decanter V101 is compressed in a compression device K101, which may be a compressor, before entering the regeneration column C102. Conversely, the compression device could potentially be replaced by an expansion device (not shown), such as a turbine. To ensure pressure balance in the different lines, one can:

[0204] - size the P102 and P104 pumps appropriately;

[0205] - and / or regulate the pressures of the V101 decanter and the C102 regeneration column independently.

[0206] Of course, the embodiments of the different figures can be combined with each other, without going out of the scope of the invention.

[0207] Furthermore, although not shown, the various lines, including the first diversion line, the second diversion line, and a possible third diversion line, may include valves to allow or prohibit traffic on these respective lines depending on the operating conditions. These valves may also advantageously allow the flow rate to be controlled at a predetermined rate, depending on the operating conditions.

[0208] Examples

[0209] The following table [Tab1] shows a comparison between the energy penalty (i.e., energy expenditure) in GJ per tonne of CO2, of a prior art solution and embodiments according to the invention, for capturing post-combustion CO2 from industrial flue gases containing 9% CO2 by volume, with the absorbent solution called DMX™, proprietary to IFP Energies nouvelles. The gain represents the reduction of this energy penalty compared to the prior art solution, expressed as a percentage.

[0210] The prior art solution corresponds to that of application EP 1 656 983 A1, which uses a separating absorbent solution with a decanter but does not use bypass lines. [Tab1]

[0211] The table clearly shows that the different embodiments of the invention make it possible to reduce energy expenditure by at least 10% compared to the prior art solution, despite the injection of at least a part of the unmixed and relatively "cold" absorbent solution into the regeneration column.

Claims

Demands 1. A process for deacidifying a gaseous effluent (FE) containing acidic compounds, such as hydrogen sulfide or sodium dioxide, in which at least the following steps are carried out: a) the gaseous effluent (FE) is contacted with an absorbent solution in an absorption column (C101), so as to obtain a gaseous effluent depleted in acid compounds (FE) and an absorbent solution loaded with acid compounds (SA), the absorbent solution being capable of forming separable phases when it has absorbed a predetermined quantity of acid compounds and is heated, b) the absorbent solution loaded with acid compounds (SA) is separated in a separation means (V101) into a gaseous fraction (FG), a first liquid fraction depleted in acid compounds (FL1) and a second liquid fraction enriched in acid compounds (FL2),c) The acid-laden absorbent solution (SA) is heated in at least one first heat exchanger (E101 A), and the acid-laden absorbent solution (SA) or the second liquid fraction (FL2) is heated in at least one second heat exchanger (E101 B), said first and second heat exchangers (E101A, E101 B) exchanging heat with a recyclable absorbent solution (SAR); d) At least one first portion of the acid-laden absorbent solution (SA) is diverted into a first bypass line (D1) upstream of the first heat exchanger (E101 A) and sent to a regeneration column (C102); e) At least one second portion of the acid-laden absorbent solution (SA) or the second liquid fraction (FL2) is diverted into a second bypass line (D2) downstream of the first heat exchanger (E101 A) and sent to the regeneration column (C102),f) the first portion of the acid-laden absorbent solution from the first bypass line (D1), the second portion of the acid-laden absorbent solution from the second bypass line (D2) or the second liquid fraction (FL2), and the remainder of the second liquid fraction (FL2) are regenerated in a regeneration column (C102) so as to release the acid compounds into an outgoing gas stream, thus forming a regenerated acid-poor absorbent solution (SR) exiting the regeneration column (C102), g) the absorbent solution to be recycled (SAR) is recycled as an absorbent solution in step a), the absorbent solution to be recycled comprising at least the solution, regenerated absorbent low in acid compounds (SR) in step f) and preferably the first liquid fraction (FL1) obtained in step b).

2. A method according to claim 1, wherein at least a part, preferably all, of the regenerated acid-poor absorbing solution (SR) exiting the regeneration column (C102) is taken and passed through a reboiler (E104) to generate steam, the steam being injected into the regeneration column (C102) to provide heat input.

3. Method according to claim 1 or 2, wherein the second liquid fraction (FL2) is heated by a heater just before being injected into the regeneration column (C102).

4. A method according to any one of the preceding claims, wherein the gaseous fraction (FG) is compressed in a compression means (K101) or expanded in an expansion means between the separation means (V101) and the regeneration column (0102).

5. A method according to any one of the preceding claims, wherein the first portion is heated by direct exchange in the regeneration column (C102) or by indirect exchange with the gaseous stream exiting the regeneration column (C102).

6. A method according to any one of the preceding claims, wherein the water vapor contained in the gas stream exiting the regeneration column (C102) is condensed in a condenser (E102) and the condensed water is discharged from a separator vessel (V102).

7. Method according to claim 6, wherein at least a portion of the condensed water discharged from the separator tank (V102) is reinjected into the upper part of the regeneration column (C102).

8. Method according to claim 6 or 7, wherein at least a portion of the condensed water discharged from the separator tank (V102) is mixed with the absorbing solution loaded with acid compounds (SA), between the absorption column (C101) and the first heat exchanger (E101 A).

9. Method according to any one of the preceding claims, wherein the separation means (V101) is positioned between the first and second heat exchangers (E101A, E101B) or between the second heat exchanger (E101B) and the regeneration column (C102).

10. A method according to any one of the preceding claims, wherein the absorbent solution loaded with acidic compounds (SA) is heated in an additional heating means (E105), upstream or downstream of the separation means (V101), preferably between the first heat exchanger (E101 A) and the separation means (V101) or between the separation means (V101) and the second heat exchanger. of heat (E101 B) or between the second heat exchanger (E101 B) and the regeneration column (C102).

11. A method according to any one of the preceding claims, wherein the gaseous fraction (FG) exiting the separation means (V101) is injected into the regeneration column (C102).

12. A method according to any one of the preceding claims, wherein said first portion and said second portion are mixed before entering the regeneration column (C102), and the mixture of the first portion and the second portion is injected at a first altitude located above a second altitude where the second liquid fraction (FL2) is injected into the regeneration column (C102).

13. A method according to any one of claims 1 to 11, wherein in the regeneration column (C102), the first portion is injected at an altitude greater than or equal to that at which the second portion is injected, itself greater than that at which the second liquid fraction (FL2) is injected, and preferably, the gaseous fraction (FG) is injected between the injection altitude of the first portion and the injection altitude of the second portion.

14. A method according to any one of the preceding claims, wherein the flow in the first bypass line (D1) and / or in the second bypass line (D2) is controlled by manual or automatic flow control means, preferably flow control valves.

15. A process according to any one of the preceding claims, wherein in step c), the acid-rich absorbent solution (SA) is heated in said first heat exchanger (E101 A) and in an intermediate heat exchanger (E101 C) and the second liquid fraction (FL2) is heated in said second heat exchanger (E101 B), said intermediate heat exchanger (E101 C) exchanging heat with the absorbent solution to be recycled (SAR).

16. A process according to claim 15, wherein, in step e), the second portion of the absorbing solution loaded with acid compounds (SA) is diverted into the second bypass line (D2) between the first heat exchanger (E101A) and the intermediate heat exchanger (E101C) and a third portion of the second liquid fraction (FL2) is diverted into a third bypass line (D3) between the separation means (V101) and the second heat exchanger (E101B), the third portion being sent to the regeneration column (C102).

17. A method according to claim 16, wherein, in the regeneration column (C102), the third portion is injected at an altitude located between the injection altitude of the second portion and the injection altitude of the remainder of the second liquid fraction (FL2).

18. A method according to any one of claims 16 or 17, wherein the flow of fluid in the third bypass line (D3) is controlled by manual or automatic flow control systems, preferably flow control valves.

19. A method according to any one of the preceding claims, wherein said absorbing solution comprises one or more reactive compounds, each selected from the group consisting of amines, alkanolamines, amino acids, alkali salts of amino acids, amides, ureas, phosphates, carbonates, and alkali metal borates, and preferably, each selected from the following list: monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxyethanol), N,N-dimethylaminoethoxyethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, N,N-bis-(3-dimethylaminopropyl)-N-isopropanolamine, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N,N-dimethylethanolamine, N-(2-aminoethyl)ethanolamine, 3-amino-1 -propanol, 3-ethoxypropylamine, N-methylethanolamine, N-methyldiethanolamine, diisopropanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethyl-1,3-propanediamine, N,N,N-tris(3-dimethylaminopropyl)amine, N,N,N',N",N'-pentamethyldipropylenetriamine, N,N,N',N'-tetramethyliminobispropylamine, N-(3-aminopropyl)morpholine, N-(2-dimethylaminoethylmorpholine, 3-methoxypropylamine, N-(2-aminoethylpiperazine, 2,2-dimorpholinodiethyl ether, N,N'-dimethylpiperazine, N,N,N',N',N"-pentamethyldiethylenetriamine, N-(3-aminopropyl)piperazine, ethyl 1-piperazinecarboxylate, dipropylenetriamine, N,N-Bis(2,2-diethoxyethylmethylamine, 3-butyl-2-(1-ethylpentyl)oxazolidine, 3-ethyl-2- methyl-2-(3-methylbutyl)oxazolidine, 1,2,2,6,6-pentamethyl-4-piperidone, 1-(2-methylpropyl)-4-piperidone, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetraethyliminobisethylamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, 1-phenylpiperazine, 1-formylpiperazine, ethyl 1-piperazine carboxylate, N,N'-di-tert-butylethylenediamine, 4-ethyl-2-methyl-2-(3-methylbutyl)oxazolidine, tetraethylenepentamine, triethylenetetramine, N,N-diethyldiethylenetriamine, N1-isopropyldiethylenetriamine, piperazine, N,N-dimethyldipropylenetriamine, diethylenetriamine, N-(2-aminoethyl)-1,3-propanediamine, 2,2'-(ethylenedioxy)diethylamine, 4-hydroxy-N-methylpiperidine, N-(2-aminoethylmorpholine, 4-amino-2,2,6,6-tetramethylpiperidine, 1,2-, diaminocyclohexane, 2-piperidinoethylamine, 2-(2-aminoethyl)-1-methylpyrrolidine, ethylenediamine, N,N-diethylethylenediamine, N-phenylethylenediamine, N-(3-aminopropyl)piperidine, furfurylamine, 2-(aminomethyl)thiophene, 4,9-dioxa-1,12-dodecanediamine, 4,7,10-trioxa-1,13-tridecanediamine, 1,2,4-trimethylpiperazine, 2-amino-2-methylpropanol, N,N'-diethyl-N,N'-dimethylethylenediamine, N,N-diethyl-N',N'-dimethylethylenediamine, 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4-dimethyl-1 ,4-diazacycloheptane, N-(2-dimethylaminoethyl)-N'-methylpiperazine, N,N,N',N'-tetraethylpropylenediamine, 1-[2-(1-piperidinyl)ethyl)]piperidine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, hexamethylenediamine, 1,2-propanediamine, 2-methyl-1,2-propanediamine, 2-methylpiperazine, N-2,N-2-dimethyl-1,2-propanediamine, N-1,N-1-dimethyl-1,2-propanediamine, 4,4'-ethylenedimorpholine, N,N,N',N'-tetraethyl-N”-methyldipropylenetriamine, 4-(dimethylamino)-1,2,2,6,6-pentamethylpiperidine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 1,5,9-trimethyl-1,5,9-triazacyclododecane, 1,4,8,1-tetramethyl-1,4,8,1-tetraazacyclotetradecane, N,N'-difurfurylethylenediamine, 1,2-Bis(2-aminoethyl)thioethane, Bis(2-aminoethyl)disulfide, Bis(2-dimethylaminoethyl)sulfide, 2,6-dimethylpiperazine, 1-ethyl-3-piperidinamine, decahydroquinoxaline, 2,3,5,6- tetramethylpiperazine, N,N-dimethyl(2-piperidinyl)methanamine, 1-(2-piperidinylmethyl)piperidine, 1-acetyl-2-diethylaminoethane, 1-amino-2-benzylaminoethane, 1-acetyl-3-dimethylaminopropane, 1-dimethylamino-3,3-diphenylpropane, N,N-dimethylbenzylamine, 2-(dimethylaminomethyl)thiophene, N,N,5-trimethylfurfurylamine, N,N-Bis(tetrahydro-2-furanylmethyl)amine, tetrahydroisoquinoline, 2-(ethylsulfanyl)ethanamine, thiomorpholine,2-[(2-aminoethyl)sulfanyl]ethanol, 2,2-dimethyl-1,3-propanediamine, N1-,N3-,2-trimethyl-1,3-propanediamine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, N1-,N1-,2,2-tetramethyl-1,3-propanediamine, 1-methoxy-2-propanamine, 3-thiomorpholinylmethanol, 2-(butylamino)ethanethiol, Bis(2-diethylaminoethyl)ether, 1-dimethylamino-2-ethylmethylaminoethoxyethane, 1,2,3-triaminopropane and N1-(2-aminopropyl)-1,2-propanediamine, tetrahydro-2-furanylmethylamine, 2,6-Dimethylmorpholine, N-methyl(tetrahydro-2-furanyl)methanamine, N,N,N',N'-tetramethyl-1,4-butanediamine, bis(2-(N,N-dimethylamino)propyl)ether, bis(2-(N,N-dimethylamino)ethyl)ether, 1,3-bis(dimethylamino)-2-propanol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethyldiethylenetriamine, 1,2-bis(dimethylaminoethyl)ethane, 1-(2-piperidinylmethyl)piperidine, 1,2,3-triaminopropane, 1,2-propanediamine, 1,3-, diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1-ethyl-3-piperidinamine, 1-methoxy-2-propanamine, 2-(2-aminoethoxy)ethanol, 2-(aminomethyl)-2-methyl-1,3-propanediamine, 2-(aminomethyl)thiophene, 2,2-dimethyl-1,3-propanediamine, 2,3,5,6-tetramethylpiperazine, 2,6-dimethylmorpholine, 2,6-dimethylpiperazine, 2-methyl-1,2-propanediamine, 2-methylpiperazine, 3-amino-1-propanol, 3-ethoxypropylamine, bis(aminoethyl)sulfide, decahydroquinoxaline, dipropylenetriamine, furfurylamine, hexamethylenediamine, N-(2-aminoethyl)ethanolamine, N-(2-aminoethyl)piperidine, N-(3-aminopropyl)piperazine, N-(3-aminopropyl)piperidine, N,N-dimethyl(2-piperidinyl)methanamine, N-1-(2-aminopropyl)-1,2-propanediamine, N-1,N-1,2,2-tetramethyl-1,3-propanediamine, N-1,N-1-dimethyl-1,2-propanediamine, N-1,N-3,2-trimethyl-1,3-propanediamine, N-2,N-2-dimethyl-1,2-propanediamine,N-butylethanolamine, N-cyclohexyl-1,3-propanediamine, N-ethylethanolamine, N-methyl(tetrahydro-2-furanyl)methanamine, N-propylethanolamine, tetrahydro-2-furanylmethylamine.

20. A method according to the preceding claim, wherein the absorbing solution comprises 10 to 100% by weight, and preferably between 20 and 70% by weight, of reactive compounds.

21. A process according to any one of claims 19 or 20, wherein the absorbent solution comprises at least one solvation compound selected from the group consisting of water, glycols, polyethylene glycols, polypropylene glycols, ethylene glycol-propylene glycol copolymers, glycol ethers, alcohols, ureas, lactams, N-alkylated pyrrolidones, N-alkylated piperidones, cyclotetramethylenesulfones, N-alkylformamides, N-alkylacetamides, ether ketones, alkyl phosphates and their derivatives.

22. A process according to claim 21, wherein the absorbing solution comprises water as a solvation compound and comprises one or more reactive compounds from the following list: N,N,N',N',N”-pentamethyldiethylenetriamine, N,N,N',N”,N'-pentamethyldipropylenetriamine, N,N-bis(2,2-diethoxyethyl)methylamine, piperazine, 2-amino-2-methylpropanol, N,N-dimethyldipropylenetriamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, 4-hydroxy-N-methylpiperidine, tetrahydroisoquinoline, N-methyldiethanolamine, N,N,N',N'-tetramethyl-1,4-butanediamine, bis(2-(N,N-dimethylamino)propyl)ether, bis(2-(N,N-dimethylamino)ethyl)ether, 1,3-bis(dimethylamino)-2-propanol, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethyldiethylenetriamine, 1,2-bis(dimethylaminoethyl)ethane.

23. A method according to any one of claims 19 to 22, wherein the absorbing solution comprises a main reactive compound and at least one secondary reactive compound, preferably the main reactive compound representing between 5 and 60% by weight of the absorbing solution and each secondary reactive compound representing between 0.5 and 30%, preferably between 0.5 and 15% and even more preferably between 1 and 10%, by weight of the absorbing solution.

24. Device for the acidification of a gaseous effluent (FE) containing acidic compounds, such as hydrogen sulfide or carbon dioxide, for implementing the process according to any one of the preceding claims, comprising: - an absorption column (C101) to bring the gaseous effluent (EF) into contact with an absorbing solution in order to produce a gas depleted in acid compounds (EFS) and an absorbing solution loaded with acid compounds (SA), the absorbing solution being chosen for its property of forming separable phases when it has absorbed a quantity of acid compounds and is heated; - a transport line for the absorbing solution loaded with acidic compounds (SA) going from the absorption column (C101) to the regeneration column (C102); - a conveying line for an absorbent solution to be recycled (SAR) from the regeneration column (C102) to the absorption column (C101); - at least one first heat exchanger (E101A) and a second heat exchanger (E101 B) to exchange heat between the fluids flowing in the transport line and in the delivery line; - the transport line comprising a separation means (V101) for separating the absorbing solution loaded with acid compounds (SA) into a gaseous fraction (FG), into a first liquid fraction (FL1) of absorbing solution depleted in acid compounds and into a second liquid fraction (FL2) of absorbing solution enriched in acid compounds; - at least one first branch line (D1) in fluidic connection between the transport line upstream of the first heat exchanger (E101 A) and the regeneration column (C102); - at least one second bypass line (D2) in fluidic connection between the transport line downstream of the first heat exchanger (E101 A) and the regeneration column (C102); - the regeneration column (C102) for releasing the acidic compounds contained at least in said second liquid fraction (FL2) and / or in at least a portion of the acid-laden absorbent solution (SA) and for producing a regenerated absorbent solution (SR) forming part of the absorbent solution to be recycled (SAR), said regeneration column (C102) preferably being equipped of at least one reboiler (E104) to form steam by vaporization of part of the regenerated absorbent solution (SR) taken from the regeneration column (C102).

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