Method for treating complex waste

Abstract

The invention relates to a method for treating a mixture M1 comprising at least organic matter, said method comprising: a. a step of hydrothermal treatment of a mixture M1 making it possible to obtain, on the one hand, liquid carbon dioxide CO2liq1 and, on the other hand, a mixture M2 comprising more than 50% by dry weight of mineral matter and organic matter in a proportion of less than 50% by dry weight, relative to the total dry weight of the mixture M2, b. a separation step carried out on at least one fraction of the mixture M2 making it possible to obtain, on the one hand, a stream M3 enriched with mineral material and, on the other hand, a stream M4 comprising organic matter and carbon dioxide, said separation step being carried out in the presence of supercritical carbon dioxide.

Description

Complex waste treatment process Technical field of the invention

[0001] The invention relates to the field of treatment of complex waste, comprising organic matter and inorganic matter, such as aqueous waste, sludge and sewage sludge. State of the art

[0002] In a context of climate change and scarcity of resources, the search for treatment processes that make it possible to best recover the energy from the various waste products produced by human activity is in full development.

[0003] Biomass and waste containing organic matter can be recovered for energy by decomposing the organic fraction to produce biogas, a fuel with high energy value, which is mainly composed of methane (50 – 60%) and CO2 (40 – 50%).

[0004] This energy conversion of the organic fraction of waste is carried out by biochemical technologies, in particular anaerobic digestion, or by thermochemical technologies such as thermal processes (combustion, pyrolysis, etc.) or hydrothermal processes (hydrothermal liquefaction / gasification, etc.).

[0005] These processes do not always provide optimum performance.

[0006] Pretreatments have been proposed to improve the processes.

[0007] The most widely applied pretreatments can be classified into three general categories:

[0008] - thermal methods (example: thermal hydrolysis),

[0009] - physical or mechanical methods (e.g. ultrasonication, high pressure homogenization, etc.),

[0010] - and chemical techniques (alkaline or acid pretreatment, oxidation by ozonation, etc.).

[0011] The object of the present invention proposes to facilitate the conversion and improve the production yield of biogas, thanks to a method of treating biomass and complex waste making it possible to optimize both the treatment itself and energy expenditure.

[0012] The invention relates to a method for treating a mixture M1 comprising at least organic matter, said method comprising:

[0013] a. a step of hydrothermal treatment of a mixture M1 making it possible to obtain, on the one hand, liquid carbon dioxide CO2liq1 and, on the other hand, a mixture M2 comprising more than 50% by dry weight of mineral matter and organic matter in a proportion of less than 50% by dry weight, relative to the total dry weight of the mixture M2,

[0014] b. a separation step implemented on at least a fraction of the mixture M2 making it possible to obtain on the one hand a flow M3 enriched in mineral matter and on the other hand a flow M4 comprising organic matter and carbon dioxide, said separation step being implemented in the presence of supercritical carbon dioxide.

[0015] According to one embodiment, the treatment method according to the invention comprises one or more of the following characteristics: - the method further comprises a step of pressurizing and / or heating liquid carbon dioxide in order to obtain supercritical carbon dioxide before its introduction during the separation step b); and / or - the method further comprises a separation step c) carried out on at least a fraction of the stream M4 in order to obtain on the one hand carbon dioxide and on the other hand a stream M5 of organic matter, said method optionally further comprising a digestion step carried out on at least a fraction of the stream M5 after possible cooling;and / or- the method further comprises a step of storing liquid carbon dioxide in a storage device, said storage device being supplied with at least a fraction of the liquid carbon dioxide from the hydrotreatment step a) CO2liq1 and where appropriate with at least a fraction of the carbon dioxide from the separation step c) of the stream M4; and / or- the treatment step a) comprises:;

[0016] • a hydrothermal treatment step of the mixture M1 making it possible to obtain a gas flow FG, an aqueous flow FL and the mixture M2,

[0017] • a liquefaction step implemented on all or part of the gas flow FG, preferably on the entire gas flow FG, making it possible to obtain a flow of liquid carbon dioxide CO2liq1 of which at least a fraction will be implemented during step b).

[0018] According to one embodiment, the hydrothermal treatment step a) comprises hydrothermal gasification, said hydrothermal gasification preferably being carried out at a temperature ranging from 350°C to 700°C, preferably from 400°C to 600°C, more preferably from 450°C to 550°C, and / or at a pressure ranging from 200 to 450 bars, preferably from 250 to 300 bars.

[0019] According to one embodiment, the hydrothermal treatment step a) comprises:- hydrothermal gasification carried out on at least a fraction of the mixture flow M1, making it possible to obtain a flow M6 comprising a mixture of gas and liquid and the flow M2,- a step of cooling and expansion of at least a fraction of the flow M6 to a temperature ranging from 30 to 150°C, preferably from 50 to 100°C and to a pressure ranging from 1 bar to 100 bars, making it possible to obtain on the one hand a gas flow M8 and on the other hand a liquid flow M7,- a step of separation of at least a fraction of the gas flow M8 making it possible to obtain on the one hand a flow enriched in carbon dioxide M9 and on the other hand a flow depleted in carbon dioxide 71,- a step of liquefaction of at least a fraction of the flow M9 making it possible to obtain a flow of liquid carbon dioxide on the one hand and a gas flow 81 on the other hand,at least a fraction of said liquid carbon dioxide stream preferably being introduced into a storage device 3.,

[0020] According to one embodiment, the hydrothermal treatment step a) comprises:- hydrothermal gasification carried out on at least a fraction of the mixture flow M1, making it possible to obtain a flow M6 comprising a mixture of gas and liquid and the flow M2,- a step of cooling at least a fraction of the flow M6 to a temperature ranging from 0 to 90°C, preferably from 10 to 70°C, preferably from 25 to 50°C, making it possible to obtain on the one hand a gas flow M10 and on the other hand a liquid flow M11, the liquid flow M11 being at a pressure ranging from 150 to 350 bars,- a step of expanding at least a fraction of the liquid flow M11 to a pressure ranging from 35 to 100 bars making it possible to obtain on the one hand a flow enriched in liquid carbon dioxide CO2liq1 and on the other hand a liquid flow M12 depleted in carbon dioxide carbon, at least a fraction of said liquid carbon dioxide stream CO2liq1 preferably being introduced into a storage device 3,preferably said method further comprises:- a separation step implemented on at least a fraction of the gas flow M10, making it possible to obtain on the one hand a flow enriched in carbon dioxide M13 and on the other hand a flow depleted in carbon dioxide M14,- an expansion step implemented on at least a fraction of the flow M13 up to a pressure ranging from 35 to 100 bars, making it possible to obtain on the one hand a flow enriched in liquid carbon dioxide CO2liq1' and on the other hand a liquid flow M15 depleted in liquid carbon dioxide, at least a fraction of said flow of liquid carbon dioxide CO2liq1' preferably being introduced into a storage device.,

[0021] According to one embodiment, the hydrothermal treatment step a) comprises a wet oxidation, preferably carried out at a temperature ranging from 250°C to 400°C, preferably from 300°C to 350°C, and / or at a pressure ranging from 40 bars to 200 bars, preferably from 60 bars to 100 bars, preferably the wet oxidation comprises:- a step of wet oxidation of the mixture M1 making it possible to obtain a liquid stream M21 and a gas stream M22,- a step of liquefaction of at least a fraction of the gas stream M22, preferably the entire gas stream M22, making it possible to obtain a liquid carbon dioxide stream CO2liq1,- a step of cooling at least a fraction of the liquid stream M21, preferably the entire liquid stream M21,- a step of filtration of the stream M21 in order to obtain an aqueous stream and the stream M2.

[0022] The present invention also relates to an installation for implementing a treatment method according to the invention, said installation comprising:- at least one hydrothermal treatment device 1 supplied with at least a fraction of the mixture M1 and comprising at least two outlets, a liquid carbon dioxide outlet line CO2liq1 and a flow outlet line M2,- a separation device 2 downstream of the flow outlet line M2 comprising at least one carbon dioxide inlet and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4.

[0023] The installation according to the invention may further comprise one or more of the following characteristics: - at least one liquid carbon dioxide storage device 3 comprising at least one inlet supplied by the liquid carbon dioxide CO2liq outlet line downstream of the hydrotreatment device 1 and comprising at least one liquid carbon dioxide CO2liq outlet, and / or - at least one pressurizing and / or heating device 4 supplied by a liquid carbon dioxide CO2liq outlet line downstream of the storage device 3 and comprising at least one supercritical carbon dioxide CO2sc outlet line, said supercritical carbon dioxide CO2sc outlet line supplying the separation device 2, - and optionally at least one recirculation loop making it possible to recirculate a fraction of the carbon dioxide recovered downstream of the separation device 2 in the flow line M4,to the separation device 2 and where appropriate to the storage device 3 or pressurizing and / or heating device 4; and / orat least one heat exchanger chosen from:• a heat exchanger 202, 31 for recovering heat from the flow of material treated in the treatment device 201, 30' and transferring it to the mixture flow M1 upstream of the treatment device 201, 30',• a heat exchanger 4, 4' for recovering heat from the flow of material treated in the treatment device 20, 201, 30, 30' and transferring it to the flow of liquid carbon dioxide upstream of the separation device 2,preferably the installation comprises said two heat exchangers.,

[0024] According to one embodiment of the installation according to the invention, the hydrothermal treatment device 1 comprises: - a hydrothermal gasification reactor 20 comprising at least one flow outlet line M6 and one flow outlet line M2, a cooling and expansion device 5 supplied with at least a fraction of the flow M6, where appropriate of the flow M6', and comprising a gas flow outlet M8 and a liquid flow outlet M7, - a separation device 6 supplied with at least a fraction of the flow M8 and comprising a carbon dioxide-enriched flow outlet line M9 and a carbon dioxide-depleted flow outlet line 71, said separation device 6 preferably being a membrane separation device or a solvent extraction device,- a liquefaction device 7 supplied with at least a fraction of the carbon dioxide-enriched flow M9 and comprising a gas flow outlet line 81 and a liquid carbon dioxide flow outlet line, said liquid carbon dioxide flow outlet line preferably supplying a storage device 3.,

[0025] According to one embodiment of the installation according to the invention, the hydrothermal treatment device 1 comprises: - a hydrothermal gasification reactor 20 comprising at least one flow outlet line M6 and one flow outlet line M2, - a cooling device 8 supplied by at least a fraction of the flow M6, where appropriate of the flow M6', and comprising a gas flow outlet M10 and a liquid flow outlet M11, - an expansion device 9 supplied by at least a fraction of the flow M11 and comprising a liquid flow outlet line M12 and a liquid carbon dioxide flow outlet line, said liquid carbon dioxide flow outlet line preferably supplying a storage device 4,said hydrothermal treatment device 1 preferably further comprising:- a separation device 10 supplied by at least a fraction of the flow M10 and comprising a carbon dioxide-enriched flow outlet line M13 and a carbon dioxide-depleted flow outlet line M14,- an expansion device 11 supplied by at least a fraction of the flow M13 and comprising a liquid carbon dioxide flow outlet line and a liquid flow outlet line M15, said liquid carbon dioxide flow outlet line preferably supplying a storage device 3.,

[0026] According to one embodiment of the installation according to the invention, the hydrothermal treatment device 1 comprises: - a wet oxidation device 30 supplied by the mixing flow line M1, and comprising at least one liquid flow outlet F21 and one gas flow outlet M22, - a liquefaction device LQ supplied by at least a fraction of the gas flow M22 and comprising at least one carbon dioxide outlet line CO2liq1, - a cooling and separation device RF supplied by at least a fraction of the liquid flow M21 and comprising at least one flow outlet line M2 and one flow outlet FL, - a separation device 2 downstream of the flow outlet line M2 comprising at least one supercritical carbon dioxide inlet CO2sc and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4,said carbon dioxide outlet line CO2liq1 being optionally connected with the supercritical carbon dioxide inlet line CO2sc, said carbon dioxide outlet line possibly comprising a storage device 3 and / or a heating and / or pressurizing device 4.,

[0027] The invention makes it possible to facilitate the recovery of mineral materials and the recovery of organic materials.

[0028] The invention thus proposes a method for treating biomass and complex waste that makes it possible to optimize the recovery of mineral and organic materials and energy expenditure while using the co-product of these energy conversions, which is CO2. Brief description of the figures

[0029] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0030] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0031] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0032] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0033] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0034] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0035] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0036] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0037] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0038] illustrates an installation for implementing a treatment method according to one embodiment of the invention.

[0039] illustrates an installation for implementing a treatment method according to one embodiment of the invention. Detailed description of the invention

[0040] The invention relates to a method for treating a mixture M1 comprising at least organic matter, said method comprising: a. a step of hydrothermal treatment of a mixture M1 making it possible to obtain, on the one hand, liquid carbon dioxide and, on the other hand, a mixture M2 comprising more than 50% by dry weight of mineral matter and organic matter in a proportion of less than 50% by dry weight, relative to the total dry weight of the mixture M2, b. a separation step carried out on at least a fraction of the mixture M2 making it possible to obtain, on the one hand, a flow M3 enriched in mineral matter and, on the other hand, a flow M4 comprising organic matter and carbon dioxide, said separation step being carried out in the presence of supercritical carbon dioxide.

[0041] For the purposes of the present invention, the expression "at least a fraction of a mixture or stream" has the same meaning as the expression "all or part of said mixture or stream". When referring to a part of said mixture or stream, this expression refers to a certain proportion of said mixture or stream. For example, for the purposes of this expression "each fraction of the mixture" or "each fraction of the stream" will have the same composition.

[0042] As used herein, the term "where appropriate" means "if applicable."

[0043] • M1 Mix

[0044] Mixture M1 is typically a biomass. The biomass can be pasty or liquid, and can be, in particular, sewage treatment plant sludge, food and agri-food waste. Preferably, it is sewage treatment plant sludge.

[0045] According to one embodiment, the mixture M1 comprises from 5 to 50% by weight of solid matter, preferably from 15 to 35% by weight of solid matter, relative to the total weight of the mixture M1.

[0046] According to one embodiment, the process of the invention comprises a grinding step and / or a hydrolysis step of the mixture M1, said hydrolysis step then preferably being carried out at a pressure ranging from 1 to 8 bars and at a temperature ranging from 70 to 165°C, in order to obtain a hydrolyzed mixture M1', at least a fraction of said hydrolyzed mixture M1' then being carried out in step a) of the process of the invention.

[0047] • Hydrothermal treatment step a)

[0048] The hydrothermal treatment step a) makes it possible to obtain at least:- a flow of carbon dioxide in liquid form and- a flow of mixture M2.

[0049] The M2 mixture includes:

[0050] - more than 50% by dry weight of mineral matter, preferably more than 70% by dry weight of mineral matter, or even more than 80% by dry weight of mineral matter, and

[0051] - less than 50% by dry weight of organic matter, preferably less than 30% by dry weight of organic matter, or even less than 20% by dry weight of organic matter,

[0052] relative to the total dry weight of the mixture M2.

[0053] Typically, the mixture stream M2 will be an aqueous stream comprising at least 30% by weight of water, preferably at least 40% by weight of water, or even at least 50% by weight of water, relative to the total weight of the mixture M2.

[0054] The hydrothermal treatment step may comprise one or more heat exchanges and / or one or more separation steps making it possible to recover at least one stream of carbon dioxide in liquid form and at least one stream of treated material M2.

[0055] According to one embodiment of the invention, the method comprises two heat exchanges: - a heat exchange X2 making it possible to transfer heat from the flow of material treated during treatment step a) to the flow of material M1 upstream of treatment step a), - a heat exchange X1, X1' making it possible to transfer heat from the flow of material treated during treatment step a) to the flow of liquid carbon dioxide upstream of separation step b) and where appropriate (i.e. if the method comprises a storage step) downstream of the storage step.

[0056] According to one embodiment of the invention, the treatment step comprises:- a treatment step making it possible to obtain a gaseous flow FG, an aqueous flow and a flow M2, the flow M2 typically being a brine type flow, the aqueous flow typically comprising a proportion of water greater than the proportion of water in the flow M2,- a liquefaction step implemented on all or part of the gaseous flow FG, preferably on the entire gaseous flow FG, making it possible to obtain a liquid carbon dioxide flow of which at least a fraction will be implemented during step b).

[0057] Hydrothermal treatment can be chosen from hydrothermal gasification (GH) and wet oxidation (WOO).

[0058] •Separation step b)

[0059] The process of the invention comprises a separation step carried out on at least a fraction of the mixture M2 making it possible to obtain: - on the one hand a flow M3 enriched in mineral matter and - on the other hand a flow M4 depleted in mineral matter, the flow M4 comprising organic matter and carbon dioxide.

[0060] This separation step b) is carried out in the presence of supercritical carbon dioxide.

[0061] In fact, the inventors discovered that supercritical carbon dioxide, due to its particular properties, made it possible to separate the mineral matter from the organic matter present in the M2 flow resulting from the hydrothermal treatment.

[0062] Supercritical carbon dioxide is carbon dioxide at a temperature of at least 31.25°C and a pressure of at least 74 bar.

[0063] Supercritical carbon dioxide is a fluid state of carbon dioxide (CO2) obtained when it is maintained above its critical temperature and pressure, respectively 31.25°C and 74 bar. At these pressures and temperatures, the state of CO2 means that it still has a significant density: 0.47 g / cm3.

[0064] Supercritical CO2 has properties that are between those of a gaseous fluid and those of a liquid. Its properties can be adjusted by changing external parameters (temperature and / or pressure).

[0065] Thanks to its viscosity, its density and a high level of diffusion, supercritical CO2 will therefore be able to enter and dissolve in biological matrices and act on the bonds between the organic matter and the water present in the matrix during the stage of separation of the organic matter (and recovery of the mineral matter).

[0066] In particular, supercritical CO2 exhibits a significant quadrupole moment and, related to its microscopic solvent behavior, this molecule can participate in hydrogen bonding interactions and act as both a weak Lewis acid and base during the organic matter separation step.

[0067] Step b) is preferably carried out in a separation device.

[0068] Supercritical carbon dioxide is preferably introduced into a separation device, through an inlet separate from that of the M2 mixture, preferably by continuous injection.

[0069] At the end of the separation step, a stream M3 enriched in mineral matter is obtained and a stream M4 comprising organic matter and carbon dioxide is obtained. The stream M4 will also be called “stream depleted in mineral matter”.

[0070] For the purposes of the present invention, in the context of a separation of a given flow X, the term "a flow enriched in mineral matter" means a flow comprising a mass proportion of mineral matter greater than the mass proportion of mineral matter in the given flow X, these mass proportions being defined in proportion to the dry matter.

[0071] For the purposes of the present invention, in the context of a separation of a given flow X, the term "flow depleted in mineral matter" means a flow comprising a mass proportion of mineral matter lower than the mass proportion of mineral matter in the given flow X, these mass proportions being defined in proportion to the dry matter.

[0072] According to one embodiment, the method further comprises a step of pressurizing and / or heating liquid carbon dioxide in order to obtain supercritical carbon dioxide before its introduction during the separation step b).

[0073] According to one embodiment, the method further comprises a separation step c) carried out on at least a fraction of the stream M4 in order to obtain, on the one hand, gaseous carbon dioxide and, on the other hand, a stream M5 of organic matter, said method optionally further comprising a digestion step carried out on at least a fraction of the stream M5 comprising organic matter. Typically, the stream of organic matter M5 will be cooled before its implementation in the digestion step.

[0074] All or part of said gaseous carbon dioxide from step c), preferably part of the gaseous carbon dioxide from step c), can be liquefied, and optionally put into supercritical form for its implementation during step b) of the invention.

[0075] According to one embodiment, the method further comprises a step of storing liquid carbon dioxide in at least one storage device, said storage device being supplied with at least a fraction of the liquid carbon dioxide from the hydrotreatment step a) and optionally, if applicable, with a fraction of the carbon dioxide from the separation step c) of the stream M5. Said fraction of gaseous carbon dioxide from separation c) can be cooled upstream of the storage device or inside the storage device in order to liquefy the carbon dioxide.

[0076] Preferably, the carbon dioxide is stored in the storage device in liquid form, typically at a temperature ranging from 56°C to 31°C and at a pressure ranging from 5 bar to 73 bar. For example, the carbon dioxide may be stored at -20°C and 20 bar.

[0077] Preferably, when such a storage device is present, at least a fraction, preferably all, of the supercritical carbon dioxide used in step b) comes from the storage device.

[0078] Thus, when the method of the invention comprises a step of pressurizing and / or heating liquid carbon dioxide in order to obtain supercritical carbon dioxide before its introduction during the separation step b), said step is preferably carried out on liquid carbon dioxide downstream of the storage device.

[0079] Depending on the temperature and pressure of the carbon dioxide from treatment step a) or, where appropriate, from the storage device, the carbon dioxide may possibly be heated and / or pressurized in order to bring the carbon dioxide to supercritical conditions, before its use in separation step b).

[0080] Depending on the temperature of the fluid M2, the carbon dioxide can be brought into contact with the fluid M2 in liquid form and brought to supercritical conditions in contact with the fluid M2 for the separation step of step b).

[0081] •Processing step a): hydrothermal gasification (GH)

[0082] According to one embodiment, the treatment step a) is a hydrothermal gasification step, preferably carried out at a temperature ranging from 350°C to 700°C, preferably from 400°C to 600°C, more preferably from 450°C to 550°C, and / or at a pressure ranging from 200 to 450 bars, preferably from 250 to 300 bars.

[0083] Hydrothermal gasification (GH) is a thermal depolymerization process used to convert organic matter present in a humid environment into a mixture comprising only small molecules under high to moderate temperature and pressure.

[0084] During GH, carbon and hydrogen in an organic material are converted thermochemically under near-critical or supercritical conditions. Some of it is converted into low-molar-mass compounds that are soluble in water.

[0085] Another part is converted into gas products such as carbon dioxide (CO2), methane (CH4), dihydrogen (H2), carbon monoxide (CO), light hydrocarbons such as ethane (C2H6) and propane (C3H8).

[0086] During the stay in the hydrothermal gasification reactor at temperatures below 400°C, the organic matter undergoes, among other reactions, a decomposition based on a very rapid homogeneous hydrolysis (a few seconds). In fact, an implementation in quasi-critical or supercritical conditions allows the use of the unique properties of supercritical water as a solvent, which allow solvation conditions and homogeneous reactions, leading to very high reaction kinetic rates. As a result, a much shorter residence time and a much higher heating rate than those of conventional hydrolysis are used, limiting or even avoiding the secondary condensation and polymerization reactions responsible for the formation of bio-oil and biochar.

[0087] When GH is operated at a temperature above 400°C, free radical decomposition of polymers (involving in particular decarboxylation, deamination by breaking CN bonds, and CC or CO cleavage reactions) is predominant, while endothermic steam reforming is the main reaction pathway to convert small molecules with 1 to 3 carbon atoms into carbon oxides and dihydrogen and nitrogen into ammonia.

[0088] Methane is also produced by methanation of CO and CO2, using dihydrogen.

[0089] Consequently, GH can be considered as a decomposition process transforming the organic residues present in the M1h stream into more easily biodegradable material and into dissolved ammonia in the liquid phase.

[0090] The treatment conditions (in particular temperature, pressure, and to a lesser extent residence time) of the GH can be adjusted to not only produce a gaseous fraction containing CH4, CO, CO2 and H2 (synthesis gas), but also to produce an aqueous effluent, containing mainly on one side easily digestible compounds, in particular carboxylic acids and on the other side ammonia in the form of ammonium salt of the carbonic acids produced.

[0091] Typically, in the context of the present invention, this GH step makes it possible to obtain a flow of mineral material M2 and a flow M6 comprising a mixture containing gas and liquid.

[0092] In the context of the present invention, the flow M2 will be referred to indifferently as the flow of inorganic matter or the flow of mineral matter.

[0093] The mineral material stream M2 will typically include a proportion of mineral material greater than the proportion of mineral material in the stream M1.

[0094] Material stream M6 will typically include a mass proportion of organic matter greater than the mass proportion of organic matter in stream M1.

[0095] Typically also, the M2 mineral matter stream will include a higher proportion of mineral matter than the proportion of mineral matter in the M6 ​​stream.

[0096] Typically also, the M6 ​​material stream will include a higher proportion of organic matter than the proportion of organic matter in the M2 stream.

[0097] Hydrothermal gasification is the name given to the entire treatment chain resulting on the one hand in the production of a gas by the transformation of organic matter and on the other hand in several liquid fractions containing more or less mineral matter.

[0098] Typically, this hydrothermal gasification includes at least the pressurization and heating of the biomass, in particular at temperatures above 350°C and at pressures allowing vaporization of the medium to be avoided.

[0099] According to one embodiment, the hydrothermal gasification is carried out in a gasification reactor:- at a temperature ranging from 400°C to 600°C, preferably from 450°C to 550°C, and / or- at a pressure ranging from 200 to 450 bars, preferably from 250 to 300 bars.

[0100] Hydrothermal gasification can also include separation of the mineral fraction (salts) M2 and can use catalysts.

[0101] Among the mineral matter, we can cite salts including anions such as phosphates, sulfates, chlorides, carbonates and hydrocarbonates with counter ions for example sodium, magnesium, calcium, ammonium and metals.

[0102] Preferably, the (overall) residence time of the M1 stream in step a) of GH typically ranges from 1 min to 20 min, preferably from 2 min to 10 min, more preferably from 3 to 5 min.

[0103] According to one embodiment, the hydrothermal gasification step is carried out in a gasification reactor in the presence of at least one catalyst. Preferably, the catalyst is chosen from metals on activated carbon, for example of the ruthenium, nickel, palladium or platinum type.

[0104] The catalyst may be in the form of a bed of solid particles within the gasification reactor.

[0105] The hydrothermal gasification step will thus generally lead to a mixture comprising inorganic matter (salts) and organic matter.

[0106] In the context of the invention, typically, the GH step comprises a separation step making it possible to obtain on the one hand a flow M2 enriched in inorganic matter and on the other hand a flow MO depleted in inorganic matter. The flow M6 will then generally be a flow of gas dissolved in a liquid effluent.

[0107] For the purposes of the present invention, in the context of a separation of a given flow X, the term "a flow enriched in inorganic matter" means a flow comprising a mass proportion of inorganic matter greater than the mass proportion of inorganic matter in the given flow X, these mass proportions being defined in proportion to the dry matter.

[0108] For the purposes of the present invention, in the context of a separation of a given flow X, the term "flow depleted in inorganic matter" means a flow comprising a mass proportion of inorganic matter lower than the mass proportion of inorganic matter in the given flow X, these mass proportions being defined in proportion to the dry matter.

[0109] According to one embodiment, at the outlet of the hydrothermal gasification, a carbon dioxide stream is obtained by a so-called "high pressure" separation or by a "low pressure" site separation implemented from at least a fraction of the M6 ​​stream from the hydrothermal gasification reactor, where appropriate the M6' or M6'' stream.

[0110] •So-called “low pressure” separation

[0111] According to one embodiment of the method of the invention, the treatment step a) is a hydrothermal gasification step comprising:- hydrothermal gasification carried out on at least a fraction of the mixture stream M1, making it possible to obtain a treated stream M6 comprising a mixture of gas and liquid and the stream M2,- a step of cooling and expanding at least a fraction of the stream M6 to a temperature ranging from 30 to 150°C, preferably from 50 to 100°C, and to a pressure ranging from 1 bar to 100 bars, making it possible to obtain on the one hand a gas stream M8 and on the other hand a liquid stream M7,- a step of separating at least a fraction of the gas stream M8 making it possible to obtain on the one hand a stream enriched in carbon dioxide M9 and on the other hand a stream depleted in carbon dioxide 71,- a step of liquefying at least a fraction of the stream M9, typically up to a temperature ranging from -56°C to 31°C and at a pressure ranging from 5 to 73 bars,allowing to obtain a flow of liquid carbon dioxide CO2liq1 on the one hand (flow enriched in CO2) and a gaseous flow 81 (flow depleted in CO2) on the other hand.,

[0112] According to an embodiment implementing a storage device, at least a fraction of said liquid carbon dioxide flow CO2liq1 is preferably introduced into the storage device.

[0113] Preferably, the liquefaction step comprises a cooling step and / or a compression step. It makes it possible to liquefy carbon dioxide.

[0114] •So-called “high pressure” separation

[0115] According to one embodiment of the method of the invention, the treatment step a) is a hydrothermal gasification step comprising:- hydrothermal gasification carried out on at least a fraction of the mixture stream M1, making it possible to obtain a treated stream M6 comprising a mixture of gas and liquid and the stream M2- a step of cooling at least a fraction of the stream M6 to a temperature ranging from 0 to 90°C, preferably from 10 to 70°C, preferably from 25 to 50°C, making it possible to obtain on the one hand a gas stream M10 and on the other hand a liquid stream M11 (stream comprising dissolved CO2), the liquid stream M11 being at a pressure ranging from 150 to 350 bars,- a step of expanding at least a fraction of the liquid stream M11 to a pressure ranging from 35 bars to 100 bars making it possible to obtain on the one hand a liquid carbon dioxide stream (stream enriched in CO2) CO2liq1 and on the other hand a liquid flow M12 (flow depleted in CO2).

[0116] According to an embodiment implementing a storage device, at least a fraction of said liquid carbon dioxide flow is preferably introduced into the storage device.

[0117] According to this so-called “high pressure” embodiment, carbon dioxide can also preferably be recovered in all or part of the gas flow M10.

[0118] Thus, according to one embodiment, the method further comprises:- a separation step implemented on at least a fraction of the gas flow M10, making it possible to obtain on the one hand a flow enriched in carbon dioxide M13 and on the other hand a flow depleted in carbon dioxide M14,- an expansion step implemented on at least a fraction of the flow M13 up to a pressure ranging from 35 to 100 bars, making it possible to obtain on the one hand a flow of liquid carbon dioxide CO2liq1' and on the other hand a liquid flow M15.

[0119] According to an embodiment implementing a storage device, at least a fraction of said liquid carbon dioxide flow CO2liq1' is preferably introduced into the storage device.

[0120] •Heat exchanges

[0121] According to one embodiment, the treatment step a) is a hydrothermal gasification making it possible to obtain at least one treated stream M6 comprising gas and liquid and the method of the invention comprises a heat exchange X1 between at least a fraction of the treated stream M6 resulting from the hydrothermal gasification step and the liquid carbon dioxide stream upstream of step b) and where appropriate downstream of the storage device and upstream of the separation step b), said heat exchange thus making it possible to at least partially heat the liquid carbon dioxide before its implementation in step b) and making it possible to at least partially cool the stream M6. The stream thus cooled will be called stream M6'.

[0122] According to this embodiment, at least a fraction of the M6' stream can be separated according to a so-called "low pressure" separation or according to a so-called "high pressure" separation as defined in the present invention in order to obtain a stream of liquid carbon dioxide CO2liq (CO2liq1).

[0123] According to one embodiment, the treatment step a) is a hydrothermal gasification comprising a preliminary step of heating the mixture flow M1, said preliminary heating step comprising at least one heat exchange sub-step X2 between the treated flow M6 resulting from the hydrothermal gasification step and the flow M1, said heat exchange X2 thus making it possible to at least partially heat the mixture M1 and to at least partially cool the treated flow M6, in order to obtain a flow M6'.

[0124] According to this embodiment, the method preferably further comprises a heat exchange X1' between the treated stream M6' and the stream of liquid carbon dioxide upstream of step b) and where appropriate downstream of the storage device and upstream of the separation step b), said heat exchange X1' thus making it possible to at least partially heat the liquid carbon dioxide before its implementation in step b) and making it possible to at least partially cool the stream M6' in order to obtain a stream M6''.

[0125] According to this embodiment, at least a fraction of the M6'' stream can be separated according to a so-called "low pressure" separation or according to a so-called "high pressure" separation as defined in the present invention in order to obtain a stream of liquid carbon dioxide CO2liq (CO2liq1 or CO2liq1').

[0126] •Treatment step a): wet oxidation (WVO)

[0127] According to one embodiment, the hydrothermal treatment step a) is a wet oxidation step, preferably carried out at a temperature ranging from 250°C to 400°C, preferably from 300°C to 350°C, and / or at a pressure ranging from 40 bars to 200 bars, preferably from 60 bars to 100 bars.

[0128] This wet oxidation step may optionally include preheating of the material (mixture M1) (i) by heat exchange with the output material (treated material comprising a liquid and gas), (ii) by additional heating of the material or (iii) by injection of oxygen (via air, pure oxygen or any other oxygenated derivative).

[0129] The wet oxidation treatment step may thus comprise:- a step of wet oxidation of the mixture M1 making it possible to obtain a liquid stream M21 and a gas stream M22,- a step of liquefaction of at least a fraction of the gas stream M22, preferably the entire gas stream M22, making it possible to obtain a liquid carbon dioxide stream,- a step of cooling at least a fraction of the liquid stream M21, preferably the entire liquid stream M21, making it possible to obtain the stream M2,- a step of separation, for example by filtration, of the liquid stream M21 in order to separate the liquid from the mineral matter, which will make it possible to obtain an aqueous stream FL and the stream of matter M2, this separation step makes it possible in particular to concentrate the stream of matter M2 into mineral matter before its implementation during step b).

[0130] The M22 gas stream contains mainly CO2 and possibly oxygen.

[0131] Cooling of the M22 gas flow can be implemented by one or more heat exchanges.

[0132] The wet oxidation step may optionally include one or two heat exchanges before a separation to obtain the M21 and M22 streams.

[0133] The separation of the M20 mixture resulting from the wet oxidation treatment can be done under pressure or after expansion of the M20 mixture.

[0134] Thus, it is possible to provide a heat exchange X1 between the flow of material treated by OVH M20 and the flow of liquid carbon dioxide upstream of step b) and where appropriate downstream of the storage device and upstream of the separation step b), this heat exchange X1 making it possible (i) to cool the treated material M20 and (ii) to heat the liquid CO2 upstream of step b) and where appropriate downstream of the storage device and upstream of the separation step b).

[0135] It is also possible to provide a heat exchange X2 between the flow of material treated by OVH M20 and the flow M1 upstream of the OVH, this heat exchange X2 allowing i) the flow of material treated by OVH M20 to be cooled and (ii) the mixture M1 to be heated or preheated upstream of the OVH.

[0136] According to an embodiment implementing an OVH treatment, the method of the invention comprises: - a first heat exchange X2 making it possible to recover heat from the treated material flow M20 (M20 comprising a mixture of gas and liquid) and to transfer it to the material flow M1 upstream of the OVH, a cooled material flow M20' is then obtained, and - a second heat exchange X1' making it possible to recover heat from the cooled material flow M20' (M20' comprising a mixture of gas and liquid) and to transfer it to the liquid carbon dioxide flow upstream of step b) and where appropriate downstream of the storage device and upstream of step b), a cooled material flow M20'' is then obtained.

[0137] According to this embodiment, typically, the material flow M20'' will then be separated to obtain on the one hand a liquid flow M21 and on the other hand a gaseous flow M22.

[0138] The present invention also relates to an installation as such and an installation for implementing the method of the invention.

[0139] The installation according to the invention comprises:- at least one hydrothermal treatment device 1 supplied with at least a fraction of the mixture M1 and comprising at least two outlets, a liquid carbon dioxide CO2liq outlet line and a flow outlet line M2,- a separation device 2 comprising at least one inlet supplied by the flow outlet line M2 and at least one supercritical carbon dioxide inlet and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4.

[0140] According to one embodiment, the installation according to the invention comprises at least one storage device 3 comprising at least one inlet supplied by the liquid carbon dioxide CO2liq outlet line downstream of the treatment device 1 and comprising at least one liquid carbon dioxide CO2liq2 outlet making it possible to supply the separation device 2 or a pressurization and / or heating device 4 located upstream of the separation device 2.

[0141] According to one embodiment, the installation according to the invention further comprises at least one separation device SP comprising at least one inlet supplied by the flow outlet line M4 and comprising at least one gaseous carbon dioxide outlet and one organic matter outlet M5.

[0142] According to an embodiment not shown in the Figures, the installation according to the invention does not include a storage device.

[0143] According to an embodiment not shown in the Figures, the installation according to the invention does not include a separation device SP.

[0144] Illustrates an embodiment of the invention, where the installation comprises: - a mixture supply line M1, - a hydrothermal treatment device 1 supplied with at least a fraction of the mixture M1 and comprising three outlets, a liquid carbon dioxide outlet line CO2liq1, a flow outlet line M2, and an aqueous flow outlet line FL, - a separation device 2 downstream of the flow outlet line M2 comprising at least one supercritical carbon dioxide inlet CO2sc and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4, - a liquid carbon dioxide storage device 3 comprising at least one inlet supplied by the liquid carbon dioxide outlet line CO2liq1 downstream of the hydrotreatment device 1 and comprising at least one liquid carbon dioxide outlet CO2liq2,

[0145] - a pressurizing and / or heating device 4 supplied by a liquid carbon dioxide CO2liq2 outlet line downstream of the storage device 3 and comprising at least one supercritical carbon dioxide CO2sc outlet line, said supercritical carbon dioxide CO2sc outlet line supplying the separation device 2, - a separation device SP downstream of the separation device 2 comprising at least one inlet supplied by the flow outlet line M4 and comprising at least one gaseous carbon dioxide outlet and one organic matter outlet M5, and - a recirculation loop making it possible to recirculate a fraction of the carbon dioxide CO2 recovered downstream of the separation device SP, to the storage device 3.

[0146] Said recirculation loop may optionally comprise a cooling and expansion device and / or the storage device 3 may optionally comprise a cooling and expansion device not shown in the figures. This makes it possible to liquefy the gaseous carbon dioxide for storage.

[0147] Preferably, said recirculation loop comprises a bypass, as illustrated in the Figures. Indeed, in the context of the process of the invention, it is preferable to recycle and reuse upstream of the separation step b) only a fraction of the carbon dioxide recovered downstream of the separation step.

[0148] According to one embodiment, the installation according to the invention comprises: - at least one liquid carbon dioxide storage device 3 comprising at least one inlet supplied by the liquid carbon dioxide outlet line CO2liq1 downstream of the hydrotreatment device 1 and comprising at least one liquid carbon dioxide outlet CO2liq2, and - at least one pressurizing and / or heating device 4 supplied by a liquid carbon dioxide outlet line CO2liq2 downstream of the storage device 3 and comprising at least one supercritical carbon dioxide outlet line CO2sc, said supercritical carbon dioxide outlet line CO2sc supplying the separation device 2, and - optionally at least one recirculation loop making it possible to recirculate a fraction of the carbon dioxide recovered downstream of the separation device 2 in the flow line M4,to the pressurizing and / or heating device 4 or, where applicable, to the storage device 3.,

[0149] According to one embodiment, the hydrothermal treatment device 1 comprises a hydrothermal gasification reactor 20 or a wet oxidation device 30.

[0150] The installation according to the invention comprising a hydrothermal gasification reactor 20 can be adapted to implement a so-called low pressure separation.

[0151] According to this embodiment, preferably, the hydrothermal treatment device 1 comprises: - a hydrothermal gasification reactor 20 comprising at least one flow outlet line M6 and one flow outlet line M2, - a cooling and expansion device 5 supplied with at least a fraction of the flow M6, where appropriate of the flow M6', and comprising a gas flow outlet M8 and a liquid flow outlet M7, - a separation device 6 supplied with at least a fraction of the flow M8 and comprising a carbon dioxide-enriched flow outlet line M9 and a carbon dioxide-depleted flow outlet line 71, said separation device 6 preferably being a membrane separation device or a solvent extraction device,- a liquefaction device 7 supplied with at least a fraction of the carbon dioxide-enriched flow M9 and comprising an aqueous flow outlet line 81 and a liquid carbon dioxide flow outlet line, said liquid carbon dioxide flow outlet line preferably supplying a storage device 3.,

[0152] The liquefaction device 7 may be a cooling device and / or a compression device.

[0153] Illustrates an embodiment where the treatment step a) is a hydrothermal gasification step where the carbon dioxide is recovered by a “low pressure” separation. As illustrated in, the treatment device 1 comprises:- a hydrothermal gasification reactor 20 comprising a flow outlet line M6 and a flow outlet line M2,- a cooling and expansion device 5 supplied by the flow line M6 and comprising a gas flow outlet M8 and a liquid flow outlet M7,- a separation device 6 supplied by the flow line M8 and comprising a carbon dioxide-enriched flow outlet line M9 and a carbon dioxide-depleted flow outlet line 71, said separation device 6 preferably being a membrane separation device or a solvent extraction device,- a liquefaction device 7 supplied by the carbon dioxide-enriched flow line M9 and comprising a gas flow outlet line 81 and a liquid carbon dioxide flow outlet line CO2liq1, said liquid carbon dioxide flow outlet line CO2liq1 preferably supplying the storage device 3.,

[0154] Illustrates an embodiment where the method comprises a heat exchange between the flow M6 leaving the hydrothermal gasification reactor and the pressurizing and / or heating device 4, which makes it possible on the one hand to cool the flow M6 (in order to obtain a flow M6') and on the other hand to heat the liquid carbon dioxide CO2liq2 (making it possible to obtain supercritical carbon dioxide CO2sc).

[0155] Thus, according to one embodiment, the hydrothermal treatment device 1 comprises a hydrothermal gasification reactor 20 comprising at least one flow outlet line M6, an installation in which the pressurizing and / or heating device 4 comprises at least one heat exchanger making it possible to recover heat from the flow M6 to transfer it to the liquid carbon dioxide upstream of the separation device 2, said heat exchanger comprising at least one flow outlet line M6' and one supercritical carbon dioxide outlet line.

[0156] The installation according to the invention comprising a hydrothermal gasification reactor 20 can be adapted to implement a so-called high pressure separation.

[0157] According to one embodiment, the hydrothermal treatment device 1 comprises: - a hydrothermal gasification reactor 20 comprising at least one flow outlet line M6 and one flow outlet line M2, - a cooling device 8 supplied by at least a fraction of the flow M6, where appropriate of the flow M6', and comprising a gas flow outlet M10 and a liquid flow outlet M11, - an expansion device 9 supplied by at least a fraction of the flow M11 and comprising a liquid flow outlet line M12 and a liquid carbon dioxide flow outlet line, said liquid carbon dioxide flow outlet line preferably supplying a storage device 3.

[0158] Preferably, according to this embodiment, the treatment device 1 further comprises: - a separation device 10 supplied by at least a fraction of the flow M10 and comprising a carbon dioxide-enriched flow outlet line M13 and a carbon dioxide-depleted flow outlet line M14, - an expansion device 11 supplied by at least a fraction of the flow M13 and comprising a liquid carbon dioxide flow outlet line and a liquid carbon dioxide flow outlet line M15, said liquid carbon dioxide flow outlet line preferably supplying a storage device 3.

[0159] Illustrates an embodiment where the treatment step a) is a hydrothermal gasification step where the carbon dioxide is recovered by a “high pressure” separation. As illustrated in , the treatment device 1 comprises: - a hydrothermal gasification reactor 20 comprising at least one flow outlet line M6 and one flow outlet line M2, - a cooling device 8 supplied by the flow line M6 and comprising a gas flow outlet M10 and a liquid flow outlet M11, - an expansion device 9 supplied by the flow line M11 and comprising a liquid flow outlet line M12 and a liquid carbon dioxide flow outlet line CO2liq1, said liquid carbon dioxide flow outlet line CO2liq1 preferably supplying a storage device 3.

[0160] The differs from the in that the process comprises a heat exchange between the flow M6 leaving the hydrothermal gasification reactor and the liquid carbon dioxide CO2liq2, for example in the pressurizing and / or heating device 4, which makes it possible on the one hand to cool the flow M6 (in order to obtain a flow M6') and on the other hand to heat the liquid carbon dioxide CO2liq2 (making it possible to obtain supercritical carbon dioxide CO2sc), upstream of the separation device 2.

[0161] Differs from the in that the treatment device 1 further comprises:- a separation device 10 supplied by the flow line M10 and comprising a carbon dioxide-enriched flow outlet line M13 and a carbon dioxide-depleted flow outlet line M14,- an expansion device 11 supplied by the flow line M13 and comprising a liquid carbon dioxide flow outlet line CO2liq1' and a liquid flow outlet line M15, said liquid carbon dioxide flow outlet line CO2liq1' preferably supplying a storage device 3.

[0162] Illustrates an embodiment where the storage device 3 comprises an inlet for the CO2liq1 flow and an inlet for the CO2liq1' flow. According to an embodiment not shown, the CO2liq1 and CO2liq1' flow lines can be combined upstream of the storage device 3.

[0163] Illustrates an embodiment of the process with low pressure separation where the process comprises a heat exchange in a heat exchanger 202 supplied by at least a fraction of the flow M6 leaving a gasification reactor 201, making it possible on the one hand to cool the flow M6 (obtaining a flow M6') and on the other hand to at least partially heat the mixture M11 upstream of the gasification reactor 201 (obtaining a flow M1').

[0164] Illustrates an embodiment of the process with high pressure separation where the process comprises a heat exchange in a heat exchanger 202 supplied with at least a fraction of the flow M6 leaving a gasification reactor 201, making it possible on the one hand to cool the flow M6 (obtaining a flow M6') and on the other hand to at least partially heat the mixture M1 upstream of the gasification reactor 201 (obtaining a flow M1').

[0165] Illustrates an embodiment of the method implementing a GH step with low pressure separation and illustrates an embodiment of the method implementing a GH step with high pressure separation.

[0166] According to an embodiment illustrated in the set, the method comprises two heat exchanges: - a first heat exchange in a heat exchanger 202 supplied with at least a fraction of the flow M6 leaving a gasification reactor 201, making it possible on the one hand to cool the flow M6 (obtaining a flow M6') and on the other hand to at least partially heat the mixture M1 upstream of the gasification reactor 201 (obtaining a flow M1'), - a second heat exchange between the flow M6' downstream of the heat exchanger 202 and the liquid carbon dioxide CO2liq2 for example in the pressurizing and / or heating device 4, which makes it possible on the one hand to cool the flow M6' (in order to obtain a flow M6'') and on the other hand to heat the liquid carbon dioxide CO2liq2 (making it possible to obtain supercritical carbon dioxide CO2sc).

[0167] According to one embodiment, the hydrothermal treatment device 1 comprises a wet oxidation device 30, 30'. According to this embodiment, the installation according to the invention may comprise: - a wet oxidation device 30, supplied by the mixing flow line M1, and comprising at least one liquid flow outlet M21 and one gas flow outlet M22, - a liquefaction device LQ supplied by at least a fraction of the gas flow M22 and comprising at least one carbon dioxide outlet line CO2liq1, - a cooling and separation device RF supplied by at least a fraction of the liquid flow M21 and comprising at least one flow outlet line M2 and one aqueous flow outlet FL, said separation device may comprise a filtration device, said separation making it possible to concentrate the flow M2 into mineral matter before its implementation in step b) of the method of the invention,- a separation device 2 downstream of the flow outlet line M2 comprising at least one supercritical carbon dioxide CO2sc inlet and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4, said carbon dioxide outlet line CO2liq1 being optionally connected with the supercritical carbon dioxide CO2sc inlet line, said carbon dioxide outlet line possibly comprising a storage device 3 and / or a heating and / or pressurizing device 4.,

[0168] Thus, according to an embodiment illustrated in the, the installation according to the invention comprises:- a wet oxidation device 30 supplied by a mixture M1, and comprising a liquid flow outlet F21 and a gas flow outlet M22,

[0169] - a liquefaction device LQ supplied by at least a fraction of the gas flow M22 and comprising at least one carbon dioxide outlet line CO2liq1 (and one gas flow outlet line),

[0170] - a cooling and separation device RF supplied by at least one fraction of liquid flow M21 and comprising at least one liquid flow outlet line FL and one flow outlet line M2, the separation device may be for example a filtration device, this separation making it possible to concentrate the flow of material M2 into mineral matter before its implementation during step b),

[0171] - a separation device 2 downstream of the flow outlet line M2 comprising at least one supercritical carbon dioxide CO2sc inlet and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4,

[0172] - a liquid carbon dioxide storage device 3 comprising at least one inlet supplied by the liquid carbon dioxide outlet line CO2liq1 downstream of the hydrotreatment device 1 and comprising at least one liquid carbon dioxide outlet CO2liq2,

[0173] - a pressurizing and / or heating device 4 supplied by a liquid carbon dioxide CO2liq2 outlet line downstream of the storage device 3 and comprising at least one supercritical carbon dioxide CO2sc outlet line, said supercritical carbon dioxide CO2sc outlet line supplying the separation device 2, - a separation device SP downstream of the separation device 2 comprising at least one inlet supplied by the flow outlet line M4 and comprising at least one gaseous carbon dioxide outlet and one organic matter outlet M5, and - a recirculation loop making it possible to recirculate a fraction of the carbon dioxide CO2 recovered downstream of the separation device SP, to the storage device 3.

[0174] Said recirculation loop may optionally comprise a cooling and expansion device and / or the storage device 3 may optionally comprise a cooling and expansion device not shown in the figures. This makes it possible to liquefy the gaseous carbon dioxide for storage.

[0175] According to an embodiment illustrated in the, the method of the invention comprises two heat exchanges. Thus, thediffers from theby the presence of these two heat exchanges:- a first heat exchange implemented in a first heat exchanger 31 making it possible to recover the heat from the flow M20 coming from the wet oxidation device 30' and to transfer it to the mixture M1 upstream of the hydrothermal treatment, a cooled flow M20' is obtained,

[0176] - a second heat exchange implemented in a second heat exchanger 4' making it possible to recover the heat from the flow M20' and transfer it to the carbon dioxide upstream of the separation device 2, the heat exchanger 4' may correspond to the pressurizing and / or heating device 4 or be a part of the pressurizing and / or heating device 4, and by the presence of a separation device SP2 supplied by the flow M20'' and comprising a liquid flow outlet F21 and a gas flow outlet M22.

Claims

Method for treating a mixture M1 comprising at least organic matter, said method comprising:a. a step of hydrothermal treatment of a mixture M1 making it possible to obtain, on the one hand, liquid carbon dioxide CO2liq1 and, on the other hand, a mixture M2 comprising more than 50% by dry weight of mineral matter and organic matter in a proportion of less than 50% by dry weight, relative to the total dry weight of the mixture M2,b. a separation step carried out on at least a fraction of the mixture M2 making it possible to obtain, on the one hand, a flow M3 enriched in mineral matter and, on the other hand, a flow M4 comprising organic matter and carbon dioxide, said separation step being carried out in the presence of supercritical carbon dioxide. A treatment method according to claim 1, further comprising a step of pressurizing and / or heating liquid carbon dioxide to obtain supercritical carbon dioxide before its introduction during separation step b). Treatment method according to claim 1 or 2, further comprising a separation step c) carried out on at least a fraction of the flow M4 in order to obtain on the one hand carbon dioxide and on the other hand a flow M5 of organic matter, said method optionally further comprising a digestion step carried out on at least a fraction of the flow M5 after possible cooling. Treatment method according to any one of claims 1 to 3, further comprising a step of storing liquid carbon dioxide in a storage device, said storage device being supplied with at least a fraction of the liquid carbon dioxide from the hydrotreatment step a) CO2liq1 and where appropriate by at least a fraction of the carbon dioxide from the separation step c) of the flow M4. Treatment method according to any one of claims 1 to 4, in which the treatment step a) comprises:- a hydrothermal treatment step of the mixture M1 making it possible to obtain a gas flow FG, an aqueous flow FL and the mixture M2,- a liquefaction step carried out on all or part of the gas flow FG, preferably on the entire gas flow FG, making it possible to obtain a liquid carbon dioxide flow CO2liq1 of which at least a fraction will be used during step b). Treatment method according to any one of claims 1 to 5, wherein the hydrothermal treatment step a) comprises hydrothermal gasification, said hydrothermal gasification preferably being carried out at a temperature ranging from 350°C to 700°C, preferably from 400°C to 600°C, more preferably from 450°C to 550°C, and / or at a pressure ranging from 200 to 450 bars, preferably from 250 to 300 bars. Treatment method according to claim 6, wherein said hydrothermal gasification step comprises:- hydrothermal gasification carried out on at least a fraction of the mixture flow M1, making it possible to obtain a flow M6 comprising a mixture of gas and liquid and the flow M2,- a step of cooling and expansion of at least a fraction of the flow M6 to a temperature ranging from 30 to 150°C, preferably from 50 to 100°C and to a pressure ranging from 1 bar to 100 bars, making it possible to obtain on the one hand a gas flow M8 and on the other hand a liquid flow M7,- a step of separation of at least a fraction of the gas flow M8 making it possible to obtain on the one hand a flow enriched in carbon dioxide M9 and on the other hand a flow depleted in carbon dioxide 71,- a step of liquefaction of at least a fraction of the flow M9 making it possible to obtain a liquid carbon dioxide flow on the one hand and a gas flow 81 on the other hand,at least a fraction of said liquid carbon dioxide stream preferably being introduced into a storage device 3., Treatment method according to claim 6, wherein said hydrothermal gasification step comprises:- hydrothermal gasification carried out on at least a fraction of the mixture flow M1, making it possible to obtain a flow M6 comprising a mixture of gas and liquid and the flow M2,- a step of cooling at least a fraction of the flow M6 to a temperature ranging from 0 to 90°C, preferably from 10 to 70°C, preferably from 25 to 50°C, making it possible to obtain on the one hand a gas flow M10 and on the other hand a liquid flow M11, the liquid flow M11 being at a pressure ranging from 150 to 350 bars,- a step of expanding at least a fraction of the liquid flow M11 to a pressure ranging from 35 to 100 bars making it possible to obtain on the one hand a flow enriched in liquid carbon dioxide CO2liq1 and on the other hand a liquid flow M12 depleted in carbon dioxide,at least a fraction of said liquid carbon dioxide flow CO2liq1 preferably being introduced into a storage device 3, preferably said method further comprises: - a separation step implemented on at least a fraction of the gas flow M10, making it possible to obtain on the one hand a flow enriched in carbon dioxide M13 and on the other hand a flow depleted in carbon dioxide M14, - an expansion step implemented on at least a fraction of the flow M13 up to a pressure ranging from 35 to 100 bars, making it possible to obtain on the one hand a flow enriched in liquid carbon dioxide CO2liq1' and on the other hand a liquid flow M15 depleted in liquid carbon dioxide, at least a fraction of said liquid carbon dioxide flow CO2liq1' preferably being introduced into a storage device., Treatment method according to any one of claims 1 to 5, wherein the hydrothermal treatment step a) comprises a wet oxidation, preferably carried out at a temperature ranging from 250°C to 400°C, preferably from 300°C to 350°C, and / or at a pressure ranging from 40 bars to 200 bars, preferably from 60 bars to 100 bars, preferably the wet oxidation comprises:- a step of wet oxidation of the mixture M1 making it possible to obtain a liquid stream M21 and a gas stream M22,- a step of liquefaction of at least a fraction of the gas stream M22, preferably the entire gas stream M22, making it possible to obtain a liquid carbon dioxide stream CO2liq1,- a step of cooling at least a fraction of the liquid stream M21, preferably the entire liquid stream M21,- a step of filtration of the stream M21 in order to to obtain an aqueous flow and the M2 flow. Installation for implementing a treatment method according to any one of claims 1 to 9, said installation comprising:- at least one hydrothermal treatment device (1) supplied with at least a fraction of the mixture M1 and comprising at least two outlets, a liquid carbon dioxide outlet line CO2liq1 and a flow outlet line M2,- a separation device (2) downstream of the flow outlet line M2 comprising at least one carbon dioxide inlet and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4. Installation according to claim 10, further comprising:- at least one liquid carbon dioxide storage device (3) comprising at least one inlet supplied by the liquid carbon dioxide CO2liq outlet line downstream of the hydrotreatment device (1) and comprising at least one liquid carbon dioxide CO2liq outlet, and / or- at least one pressurizing and / or heating device (4) supplied by a liquid carbon dioxide CO2liq outlet line downstream of the storage device (3) and comprising at least one supercritical carbon dioxide CO2sc outlet line, said supercritical carbon dioxide CO2sc outlet line supplying the separation device (2),- and optionally at least one recirculation loop making it possible to recirculate a fraction of the carbon dioxide recovered downstream of the separation device (2) in the flow line M4,to the separation device (2) and where appropriate to the storage device (3) or pressurizing and / or heating device (4)., Installation according to claim 10 or 11, comprising at least one heat exchanger chosen from:- a heat exchanger (202, 31) making it possible to recover heat from the flow of material treated in the treatment device (201, 30') and to transfer it to the flow of mixture M1 upstream of the treatment device (201, 30'),- a heat exchanger (4, 4') making it possible to recover heat from the flow of material treated in the treatment device (20, 201, 30, 30') and to transfer it to the flow of liquid carbon dioxide upstream of the separation device (2), preferably the installation comprises said two heat exchangers. Installation according to any one of claims 10 to 12, in which the hydrothermal treatment device (1) comprises:- a hydrothermal gasification reactor (20) comprising at least one flow outlet line M6 and one flow outlet line M2,- a cooling and expansion device (5) supplied with at least a fraction of the flow M6, where appropriate of the flow M6', and comprising a gas flow outlet M8 and a liquid flow outlet M7,- a separation device (6) supplied with at least a fraction of the flow M8 and comprising a carbon dioxide-enriched flow outlet line M9 and a carbon dioxide-depleted flow outlet line 71, said separation device (6) preferably being a membrane separation device or a solvent extraction device,- a liquefaction device (7) supplied with at least a fraction of the carbon dioxide-enriched flow M9 and comprising a gas flow outlet line 81 and a liquid carbon dioxide flow outlet line, said liquid carbon dioxide flow outlet line preferably supplying a storage device (3)., Installation according to any one of claims 10 to 12, in which the hydrotreatment device (1) comprises: - a hydrothermal gasification reactor (20) comprising at least one flow outlet line M6 and one flow outlet line M2, - a cooling device (8) supplied with at least a fraction of the flow M6, where appropriate of the flow M6', and comprising a gas flow outlet M10 and a liquid flow outlet M11, - an expansion device (9) supplied with at least a fraction of the flow M11 and comprising a liquid flow outlet line M12 and a liquid carbon dioxide flow outlet line, said liquid carbon dioxide flow outlet line preferably supplying a storage device (4),said hydrothermal treatment device (1) preferably further comprising:- a separation device (10) supplied with at least a fraction of the flow M10 and comprising a carbon dioxide-enriched flow outlet line M13 and a carbon dioxide-depleted flow outlet line M14,- an expansion device (11) supplied with at least a fraction of the flow M13 and comprising a liquid carbon dioxide flow outlet line and a liquid flow outlet line M15, said liquid carbon dioxide flow outlet line preferably supplying a storage device (3)., Installation according to any one of claims 10 to 12, in which the hydrotreatment device (1) comprises: - a wet oxidation device (30) supplied by the mixing flow line M1, and comprising at least one liquid flow outlet F21 and one gas flow outlet M22, - a liquefaction device LQ supplied by at least a fraction of the gas flow M22 and comprising at least one carbon dioxide outlet line CO2liq1, - a cooling and separation device RF supplied by at least a fraction of the liquid flow M21 and comprising at least one flow outlet line M2 and one flow outlet FL, - a separation device (2) downstream of the flow outlet line M2 comprising at least one supercritical carbon dioxide inlet CO2sc and comprising at least two outlets, a flow outlet line M3 and a flow outlet line M4,said carbon dioxide outlet line CO2liq1 being optionally connected with the supercritical carbon dioxide inlet line CO2sc, said carbon dioxide outlet line possibly comprising a storage device (3) and / or a heating and / or pressurizing device (4).,

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