Method for treating composite waste

Abstract

The invention relates to a method for treating a mixture M1 comprising at least an organic material, said method comprising: a) a step of hydrolyzing the mixture M1 to obtain a hydrolyzed mixture M1h, b) a step of pressurizing the mixture M1h to obtain a mixture stream M1p, c) a step of heating the mixture M1p obtained from step b) to obtain a mixture M2, d) a step of solubilizing at least a portion of the mixture M2 obtained in step c), optionally a heating step, and a separation step, to obtain a mixture stream M4 rich in soluble substances and a mixture stream M3 lean in soluble substances, e) a step of cooling and decompressing at least a portion of the mixture stream M4 rich in soluble substances obtained in step d) to obtain a mixture stream M5, f) a step of digesting at least a portion of the mixture stream M5 obtained in step e).

Description

Technical Field

[0001] The present invention relates to the field of treatment of composite waste materials comprising organic and inorganic substances, such as aqueous waste, sewage sludge and purification sludge. Background Art

[0002] Sludge digestion is the process of partial biological degradation of organic matter in a digester, which involves a series of reactions that ultimately form a gas mixture called biogas. Biogas is an energy source that can be used in the form of electricity, heat or as a fuel, for example as a vehicle fuel or by injection into the city gas system.

[0003] The digestion process involves microorganisms, primarily bacteria, which break down or convert the feedstock to produce biogas and wastewater. The process involves a series of reactions involving bacteria, primarily hydrolysis, acidogenesis, acetogenesis, and methanogenesis.

[0004] In the following, the term "biogas" will denote the gas produced by the digestion process. This biogas contains a mixture consisting essentially of methane, carbon dioxide and water. Biogas may optionally contain other gases, such as hydrogen, oxygen, nitrogen or hydrogen sulfide, but they together account for less than 10% of the biogas. Biogas can be burned directly with oxygen and used as fuel. The methane contained in biogas (called biomethane) can also be concentrated to replace natural gas.

[0005] The treatment methods of the prior art are usually not selective enough. The conversion efficiency of most organic substances is low, and the organic substance yield is usually only 30-35%.

[0006] The application of thermal hydrolysis techniques can increase digestion yields by 5% to 15%. These techniques, either batch or continuous, are based on temperatures of 140-170°C and residence times of 30 minutes. This is certainly beneficial for increased yields, but most of the increased yield is used for heating the equipment, as heat recovery usually requires heating the initial product to about 100°C.

[0007] Furthermore, these treatments focus mainly on the organic portion of the material, while neglecting the importance of recovering the phosphorus-rich inorganic portion, for example.

[0008] Therefore, there is a need to propose a treatment method with high yield, good thermal management and improved quality of the treated material to achieve valorization of waste containing organic and inorganic materials. Summary of the invention

[0009] The present invention relates to a method for treating a mixture M1 comprising at least organic matter, the method comprising:

[0010] a) a hydrolysis step of hydrolyzing the mixture M1 at a temperature ranging from 70° C. to 165° C. and a pressure ranging from 1 bar to 8 bar to obtain a hydrolyzed mixture M1h, the ratio of the viscosity of the mixture M1 to the viscosity of the mixture M1h being at least 2,

[0011] b) a pressurization step: pressurizing the mixture M1h to a pressure ranging from 20 to 350 bar to obtain a mixed flow M1p,

[0012] c) a heating step: heating the mixed stream M1p obtained in step b) to a temperature of 250° C. to 450° C. to obtain a mixture M2,

[0013] d) a solubilization step of solubilizing at least a portion of the mixture M2 obtained in step c), optionally a heating step of heating to a temperature of 250° C. to 450° C., and a separation step to obtain a mixture stream M4 rich in soluble substances and a mixture stream M3 poor in soluble substances,

[0014] The step d) is carried out in one or more reactors, with a total hydraulic retention time of less than or equal to 20 minutes,

[0015] e) cooling and decompression step: cooling and decompressing at least a portion of the mixed stream M4 rich in soluble substances obtained in step d) to obtain a mixed stream M5,

[0016] f) Digestion step: digesting at least a portion of the mixed stream M5 obtained in step e).

[0017] According to one embodiment, the method of the present invention further comprises an additional separation step e') to separate at least a portion of the mixed flow M5 obtained in step e) to obtain a gas portion FG and a liquid flow M5', and then subjecting at least a portion, preferably all, of the liquid flow M5' to a digestion step f) in a digester, and preferably the gas portion FG is also introduced into the digester during the digestion step f).

[0018] Preferably, the separation step comprises extracting a mixed stream M4 enriched in soluble matter and extracting a mixed stream M3 depleted in soluble matter, preferably through two independently controlled outlets.

[0019] According to one embodiment, the heating step c) comprises at least two sub-steps, at least one of which is capable of heating the mixture M1p at a rate greater than or equal to 100°C / min, preferably greater than or equal to 200°C / min, more preferably greater than or equal to 400°C / min.

[0020] Preferably, heat is recovered from the mixed stream M4 enriched in soluble substances obtained in step d). Preferably, heat is recovered by heat exchange between the mixed stream M4 enriched in soluble substances obtained in step d) and the mixture M1p, preferably, said heat exchange making it possible to at least partially heat the mixture M1p during the heating step c).

[0021] According to one embodiment, during step e), the mixed stream M4 rich in soluble matter is cooled to 60° C. or below, preferably to 40° C. or below.

[0022] According to one embodiment, the cooling step includes at least two sub-steps. Preferably, the first sub-step is to perform heat exchange between the mixed flow M4 and the mixture M1p to obtain a cooled mixed flow M4', and the second sub-step is to decompress the cooled mixed flow M4' to 2 to 10 bars to generate reduced pressure steam, which can be optionally injected into the mixture M1 upstream of step a) or during step a).

[0023] According to one embodiment, the content of solid matter in the mixture M1 is 5% to 50% by weight, preferably 15% to 25% by weight, relative to the total weight of the mixture M1.

[0024] According to one embodiment, at least one additive is added to at least one mixed stream selected from:

[0025] - a mixed stream M1 upstream of step a),

[0026] - the mixture M1 during step a),

[0027] - a mixed stream M1h upstream of step b),

[0028] - a mixed stream M1p upstream of step c),

[0029] - the mixture M1p during step c),

[0030] - the mixed flow during step d),

[0031] - A mixed stream M3 poor in soluble substances obtained from step d).

[0032] According to one embodiment, the method of the invention further comprises at least one recycling step of at least a portion of the mixed stream M3, said at least one recycling step preferably being chosen from a hydrothermal gasification step and a wet oxidation step.

[0033] The invention also relates to a device for implementing the treatment method according to the invention, said device comprising:

[0034] at least one hydrolysis reactor 1, optionally comprising stirring means, which is fed at its inlet by a conveying line of the mixture M1 to be treated and comprises an outlet line for the hydrolysis mixture, said at least one hydrolysis reactor optionally being provided with a grinding device at the front end, or being equipped with a circulation circuit with a grinding device, or being provided with a grinding device at the rear end and upstream of the pump 3,

[0035] a pressure pump 3 which is fed at its inlet with the hydrolysis mixture, optionally ground, and comprises an outlet line for the mixture M1p,

[0036] a heating device 4 comprising an inlet for introducing at least a portion of the mixture M1p downstream of the pump 3 and comprising at least one outlet for the mixture M2,

[0037] a reactor 5 comprising an inlet for introducing at least a portion of the mixture M2 coming from the heating device 4 and comprising at least two outlets, one for the mixture flow M3 and the other for the mixture flow M4,

[0038] The reactor 5 may optionally include a heating device, and

[0039] The reactor 5 comprises a separation device for extracting a mixed flow M3 poor in soluble substances and a mixed flow M4 rich in soluble substances,

[0040] an optional heat exchanger 9 for recovering the heat present in the mixed flow M4 rich in soluble substances at the outlet of the reactor 5,

[0041] a pressure reduction device 10 which is fed with at least a portion of the previously cooled mixed flow M4 rich in soluble substances and comprises an outlet for the mixed flow M5,

[0042] an optional separation device 12 which is fed with at least a portion of the mixed flow M5 and comprises an outlet for the gaseous portion and an outlet for the liquid flow M5',

[0043] A digestion unit 11 supplied with at least part of the mixed stream M5 or, where appropriate, with at least part of the liquid stream M5 ′ and at least part of the gaseous fraction.

[0044] According to one embodiment, the reactor 5 comprises:

[0045] a solubilization reactor 52 comprising an inlet for introducing at least a portion of the mixture M2 coming from the heating device 4 and comprising an outlet line for the mixture M6,

[0046] - optionally a heating device 53 comprising an inlet for introducing at least a portion of the mixture M6 coming from the solubilization reactor 52 and comprising an outlet line for the mixture M6',

[0047] A separation device 51 , fed with at least a portion of the mixture M6 or at least a portion of the mixture M6 ′ (when the heating device 53 is present) and comprising at least two outlets, one for the mixed flow M3 and another for the mixed flow M4 .

[0048] According to one embodiment, the heating device 4 comprises a heat exchanger capable of exchanging heat between the mixed flow M4 rich in soluble substances coming from the reactor 5 and the mixed flow M1p downstream of the booster pump 3, thereby obtaining a cooled mixed flow M4'.

[0049] According to one embodiment, the plant also comprises a heat exchanger 9 arranged downstream of the heating device 4 and capable of recovering the heat present in the mixed flow M4 ′ and transferring it to the mixture M1 for thermal hydrolysis, preferably by generating steam.

[0050] The invention enables improved processing of organic matter in complex matrices. The improved processing allows better utilization of inorganic materials, such as salts, on the one hand, and of organic materials, on the other hand.

[0051] The processing method according to the present invention can achieve low-energy consumption operation without reducing the quality of resource recovery.

[0052] The inventors have observed that increasing the temperature above the hydrolysis temperature can result in the production of compounds that may be difficult to digest, particularly due to the long residence time, which can lead to the reorganization of these short-chain molecules produced by hydrolysis or by free radical damage at high temperatures. Therefore, the present invention improves digestibility by controlling the residence time at these high temperatures, particularly the rate at which the temperature is increased.

[0053] The invention also proposes a solubilization step, which enables water to act as a catalyst for the chemical reaction, making it possible to obtain a more homogeneous mixture in which all materials are in close contact with water. This solubilization step is carried out under controlled temperature and residence time conditions, which improves the quality of the treated material and thus its digestibility.

[0054] BRIEF DESCRIPTION OF THE DRAWINGS

[0055] [ Figure 1 ] is a schematic diagram of the processing method according to the present invention.

[0056] [ Figure 2 ] is a schematic diagram of the processing method according to the present invention.

[0057] [ Figure 3 ] is a schematic diagram of the processing method according to the present invention.

[0058] Detailed Description of the Invention

[0059] The present invention relates to a method for treating a mixture M1 comprising at least organic matter, the method comprising:

[0060] a. a hydrolysis step: hydrolyzing the mixture M1 at a temperature of 70°C to 165°C and a pressure of 1 bar to 8 bar to obtain a hydrolyzed mixture M1h, wherein the ratio of the viscosity of the mixture M1 to the viscosity of the mixture M1h is at least 2, preferably at least 4, more preferably at least 10,

[0061] b. a pressurizing step: pressurizing the mixture M1h to a pressure of 20 to 350 bar, preferably 170 to 210 bar, to obtain a mixed flow M1p,

[0062] c. Heating step: heating the mixed stream M1p obtained in step b) to 250 to 450°C, preferably 250 to 400°C, more preferably 250 to 350°C to obtain a mixed stream M2,

[0063] d. a solubilization step of solubilizing at least a portion (preferably all) of the mixed stream M2 obtained in step c), optionally heating it to a temperature of 250° C. to 450° C., preferably 250° C. to 400° C., more preferably 300° C. to 350° C., and a separation step to obtain a mixed stream M4 rich in soluble substances and a mixed stream M3 poor in soluble substances,

[0064] Said step d) is carried out in one or more reactors, and the total hydraulic retention time is less than or equal to 20 minutes, preferably less than or equal to 10 minutes, more preferably less than or equal to 5 minutes,

[0065] e. Cooling and decompression step: at least a portion, preferably all, of the mixed stream M4 rich in soluble substances obtained in step d) is cooled and decompressed to obtain a mixed stream M5,

[0066] e '. Additional separation step: Optionally, at least a portion (preferably all) of the mixed stream M5 obtained in step e) is separated to obtain a gaseous portion FG and a liquid stream M5 ',

[0067] f. Digestion step: digest at least part, preferably all, of the mixed stream M5 obtained in step e), or where appropriate (ie, when step e' is present) at least part, preferably all, of the liquid stream M5', and digest at least part of the gaseous portion FG.

[0068] Within the meaning of the present invention, the expression "at least a part of a mixture or a mixed stream" has the same meaning as the expression "all or a part of said mixture or mixed stream". When referring to said mixture or a part of said mixed stream, the expression refers to a certain proportion of said mixture or said mixed stream. For example, "every part of a mixture" or "every part of a mixed stream" will have the same composition in the sense of this expression.

[0069] Therefore, within the meaning of the present invention, the expression “step X performed on the entire mixed flow M resulting from step Y” means that steps X and Y are consecutive and that there are neither intermediate steps nor intervals between steps X and Y.

[0070] Within the meaning of the present invention, the expression "where appropriate in step X" introduces a feature that is present when step X is present.

[0071] Within the meaning of the present invention, the expression "where appropriate in the case of a mixture stream X" introduces features which are present when the mixture stream X is present.

[0072] Mixtures containing at least organic matter M1

[0073] The mixture M1 contains at least organic matter. Typically, the mixture M1 also contains inorganic materials. Among the inorganic materials, there may be, for example, salts containing anions, such as phosphates, sulfates, chlorides, carbonates and bicarbonates, and their corresponding cations are, for example, sodium, magnesium, calcium, ammonium and metal ions.

[0074] The mixture M1 can be selected, for example, from primary sludge, mixed sludge or biological sludge from municipal and industrial purification plants.

[0075] According to one embodiment, the solid matter content of the mixture M1 is 5% to 50% by weight, preferably 15% to 25% by weight, relative to the total weight of the mixture M1.

[0076] Hydrolysis step a)

[0077] The method according to the invention comprises a hydrolysis step of subjecting the mixture M1 to hydrolysis.

[0078] The hydrolysis step is carried out at a temperature ranging from 70 to 165° C. and a pressure ranging from 1 to 8 bar. These conditions make it possible to avoid evaporation of the medium.

[0079] According to one embodiment, the temperature during the hydrolysis step a) ranges from 100 to 165°C, or even from 140 to 165°C.

[0080] The hydrolysis step makes it possible to reduce the viscosity of the mixture. Step a) thus makes it possible to obtain a hydrolysis mixture M1h, also called hydrolyzate.

[0081] The hydrolysis step makes it possible to degrade the organic substances, in particular it makes it possible to break the chemical bonds and depolymerize the organic substances by the action of water.

[0082] The viscosity of mixture M1h is typically at least 2 times lower, preferably at least 4 times lower, more preferably at least 10 times lower than the viscosity of mixture M1.

[0083] Thus, the ratio of the viscosity of mixture M1 to the viscosity of mixture M1h is at least 2, preferably at least 4, more preferably at least 10.

[0084] The viscosity defined in the context of the present invention is the kinematic viscosity, measured at the same temperature (e.g. 20° C.) by using a rheometer (cylinder-cylinder, plane-plane) suitable for the viscosity to be measured and at the same shear rate (in s -1 Both viscosities are measured in 200 μm / s (in units), taking usual care to eliminate turbulence problems and to obey rheological rules (e.g., adjusting the spacing between cylinders according to particle size).

[0085] The hydrolysis step of the mixture M1 can be carried out in one or more hydrolysis reactors connected in parallel or in series.

[0086] The hydrolysis step achieves hydrolysis of the mixture M1 by maintaining an average hydraulic retention time at a desired temperature and pressure (preferably a temperature of 70 to 165° C. and a pressure of 1 to 8 bar). It should be understood that if the hydrolysis step is carried out in multiple hydrolysis reactors, the temperature in different reactors may be the same or different, and the pressure in different reactors may also be the same or different.

[0087] Advantageously, the hydrolysis step also includes an internal energy recovery step, thereby minimizing the heat consumption of the hydrolysis. For example, an energy recycling loop from the hot hydrolysis product to the cold material to be hydrolyzed can be set, for example by generating reduced pressure steam of the hot hydrolysis product and injecting it into the cold material to be hydrolyzed or heat exchange.

[0088] At the outlet of the hydrolysis step, a hydrolyzate M1h is obtained which is not necessarily at the temperature and pressure required for the hydrolysis. In fact, before the end of the hydrolysis step, the hydrolyzate may undergo a cooling and / or decompression step.

[0089] In particular, for example, if the hydrolysis is carried out at high temperature, for example in the range of 100 to 165°C, it may be desirable to cool the hydrolysate, for example to a temperature below 90°C, so that the mixed stream M1h has a lower temperature during the pressurization of step b) of the process of the invention.

[0090] The extraction of the hydrolysate M1h can be controlled by measuring the viscosity.

[0091] In the context of the treatment process of the invention, the hydrolysis step makes it possible to achieve a dual purpose:

[0092] On the one hand, by reducing the viscosity, the hydrolysis will allow better heat exchange and therefore a more rapid heating of the mixture M1p. Furthermore, the reduction in viscosity will also ensure temperature homogeneity of the mixture M1p during the heating step into M2 and will reduce or even avoid harmful carbonization reactions.

[0093] - On the other hand, by hydrolysis, most of the solid matter of the mixture M1 will come into contact with water, thereby improving the quality of the mixture M1h (more homogeneous), so as to prepare a soluble stream via a more homogeneous solubilization reaction (by maximizing the amount of soluble matter and minimizing the amount of indigestible matter), which will improve the quality of the digestion step. In other words, hydrolysis will make it possible to accelerate the solubilization in step d) and will make the solubilization more homogeneous, and these advantages are more significant, especially when the hydrolysis is combined with the grinding step.

[0094] According to one embodiment, the additive is added to the mixture M1 to be treated upstream of the hydrolysis unit, or to the mixture during the hydrolysis, or to the mixture M1h downstream of the hydrolysis unit.

[0095] According to one embodiment, a controlled amount of steam can be injected into the hydrolysis reactor and diffused through the mixture M1. This control can be performed by measuring the temperature in the hydrolysis reactor. Thus, when the set temperature is reached, the steam injection can be stopped.

[0096] Steam can be injected by:

[0097] - injection at the upstream inlet of the hydrolysis unit, using a mixer of the dynamic mixer type, and / or

[0098] - direct injection into the hydrolysis reactor, preferably in a tangential direction at the bottom of the reactor to avoid clogging with sludge, and / or

[0099] - Injection into the recirculation loop of hydrolyzed sludge.

[0100] According to one embodiment, during the hydrolysis process, the mixture M1 is mixed, for example by stirring.

[0101] The hydrolysis reactor may be a batch reactor, optionally equipped with a stirring device.

[0102] Prior to the pressing step b), the treatment method optionally comprises a grinding step, preferably mechanical grinding.

[0103] When present, the grinding step of the mixture M1 can be carried out before, during or after the hydrolysis. In the last case, the mixture M1h is ground.

[0104] When the hydrolysis step of the method of the present invention is carried out in combination with the grinding step, it may also optionally include a recycling step of recycling at least a portion of the ground hydrolysate to the inlet of the hydrolysis step.

[0105] According to one embodiment, the hydrolysis reactor comprises a recirculation loop equipped with a grinding device, so that at least a part of the hydrolysate can be introduced into the grinding device and at least a part, preferably all, of the ground hydrolysate is returned to the inlet of the hydrolysis step.

[0106] The purpose of this grinding step is to reduce the particle size of the mixture M1, generally so that the particle size of the solid fraction is less than 1000 μm, preferably less than 500 μm, preferably less than 100 μm.

[0107] The particle size "less than X μm" means that 95% of the solid particles are retained by the X μm square sieve, and the remaining 5% of the particles are no larger than 3 times of X μm.

[0108] Besides reducing the particle size to minimize downstream clogging, the grinding step also makes it possible to homogenize the mixture M1 and reduce the viscosity, thus allowing better control of the heating and solubilization steps.

[0109] Similar to the hydrolysis step, grinding and particle size reduction also aids in homogenization of the biomass and its solubilization.

[0110] In high-pressure reactors, mechanical stirring is difficult to achieve, and the reduction in viscosity achieved by the hydrolysis step and / or the grinding step also makes it possible to improve the internal turbulence and thus the homogenization in the high-pressure reactor.

[0111] Pressurization step b)

[0112] The method according to the invention comprises a pressurization step of the mixture M1h to 20 to 350 bar, preferably 50 to 300 bar, preferably 150 to 270 bar, preferably 170 to 220 bar, preferably 170 to 210 bar. A mixed stream M1p is thus obtained.

[0113] In particular, the pressurization brings the mixture M1h to a pressure sufficient to keep the mixture primarily in the liquid phase. More specifically, the pressure in the mixture M4 is typically higher than the saturated vapor pressure of the mixture M4 to keep the water in the liquid phase.

[0114] For the pressurization step, a pump may be provided on the line at the outlet of the hydrolysis reactor.

[0115] In another embodiment, a pump provided for this purpose is used for pressurization.

[0116] Heating step c)

[0117] The method according to the present invention comprises a heating step of heating the mixture M1h obtained in step b) to a temperature ranging from 250 to 450°C, preferably from 250 to 400°C, more preferably from 300 to 400°C.

[0118] At the end of heating step c) a mixed stream M2 is obtained.

[0119] The heating step can be carried out in a heat exchanger, for example by using the mixed stream M4 rich in soluble substances obtained in step d) of the method as a heating fluid for heat exchange.

[0120] The heating step c) may optionally comprise a plurality of heating sub-steps via one or more heat exchangers.

[0121] Preferably, at least one heating sub-step uses the mixed stream M4 enriched in soluble substances obtained in step d) of the method as a heating fluid for heat exchange.

[0122] Advantageously, when the heating step comprises at least two heating sub-steps, at least one of these sub-steps is performed at a high rate.

[0123] Therefore, according to a preferred embodiment, the heating rate of at least one heating sub-step is greater than or equal to 100°C / min, preferably greater than or equal to 200°C / min, more preferably greater than or equal to 400°C / min.

[0124] Therefore, in order to achieve high heating rates when using a heat exchanger, it is necessary to have as high an average temperature difference ΔT as possible in at least one heating sub-step, typically greater than 50°C, preferably greater than 100°C, more preferably greater than 200°C.

[0125] The average temperature difference ΔT is the average of the temperature differences at all points of the exchanger. The average temperature difference ΔT can be determined by calculating as the logarithmic temperature difference of the inlet temperature and the outlet temperature for each fluid.

[0126] Therefore, the heating step c) can be a combination of the following two methods: on the one hand, heat exchange with the mixed flow M4, but its absolute temperature is limited by the process requirements; on the other hand, heat exchange with another fluid, which can itself obtain heat directly through electricity, hot gas or from an external heat source, or finally, the heat exchanger can be heated by induction heating, resistance heating or microwave heating.

[0127] Therefore, a heat exchanger may be arranged downstream of the booster pump, said heat exchanger being configured to recover the heat generated by the soluble substance-rich mixture stream M4 generated in step d) and to heat the mixture M1p before the solubilization step d).

[0128] According to one embodiment, additives are added to the mixed flow M2 during the heating step of step c), before the solubilization step, and / or after step c).

[0129] According to one embodiment, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air or permanganates (such as potassium permanganate, or from alkaline agents such as KOH, NaOH, KHCO3, K2CO3, CaO, Ca(OH)2, CaCO3, Ca(HCO3)2, Mg(OH)2, MgO.

[0130] If the process comprises a step of adding an additive of the oxidizing agent type, this addition step is preferably carried out in the mixed stream M2 after the heating step c).

[0131] According to an advantageous embodiment, the device for implementing the method comprises at least one heat exchanger whose dimensions are set to enable rapid heating of the mixture M1p, for example a heating rate greater than or equal to 100°C / minute, preferably greater than or equal to 200°C / minute, more preferably greater than or equal to 400°C / minute.

[0132] Viscosity is a key factor in increasing heating rate.

[0133] Therefore, the hydrolysis step a) is advantageously carried out such that the viscosity of the hydrolysis waste (M1p) is matched to the heating rate required in step c).

[0134] If the design (set) temperature is not reached at the outlet of the heating step c), this indicates that the viscosity in the mixture M1h is still too high. The viscosity reduction can also be verified by measuring the viscosity at the outlet of the hydrolysis.

[0135] According to one embodiment, the method comprises continuous measurement of the viscosity in the mixture M1h.

[0136] If the heating rate in step c) is too low, uncontrollable side reactions (char-tar) may occur due to too long a residence time.

[0137] Step d)

[0138] Step d) of the method of the present invention comprises:

[0139] - a solubilization step (d1) of solubilizing at least a portion of the mixture M2 obtained in step c),

[0140] - an optional heating step (d2), heating at a temperature between 250°C and 450°C, and

[0141] - a separation step (d3) to obtain a mixed stream M4 enriched in soluble substances and a mixed stream M3 depleted in soluble substances.

[0142] Step d) of the process is carried out in one or more reactors with a total hydraulic retention time of less than or equal to 20 minutes, preferably less than or equal to 10 minutes, preferably less than or equal to 5 minutes.

[0143] The total hydraulic retention time is the average residence time of the droplets of M2 from the inlet of the mixture M2 (beginning of step d)) to the outlet of the stream M4 rich in soluble substances (end of step d)).

[0144] The reactor capable of carrying out step d) may be a tubular reactor and / or a continuously stirred tank reactor and / or a baffled tank reactor or other types of reactors capable of having a uniform residence time in the reactor, optionally comprising one or more filters.

[0145] Solubilization step d1)

[0146] The method according to the invention comprises a solubilization step d1) of solubilizing at least a portion of the mixture M2 resulting from step c). Preferably, this solubilization step is performed on the entire mixture M2 resulting from step c).

[0147] The solubilization step makes it possible to homogenize the organic substances of the mixture M2 in the hydrothermal medium and to render at least a portion of the organic substances of the mixture M2 soluble.

[0148] Thus, typically, the solubilization step is distinct from the liquefaction step, in which the organic material becomes insoluble in water (forming oil) and can therefore be separated from the water.

[0149] Advantageously, the solubilization step does not involve the formation of oil.

[0150] The solubilization step is used to prepare mixture M6, also referred to as liquid solution M6.

[0151] Therefore, the liquid solution M6 generally contains at least organic matter and inorganic matter.

[0152] According to one embodiment, the solubilization step is carried out in a tubular reactor or in a continuous stirred tank reactor.

[0153] Preferably, the residence time in the solubilization step d1) is less than or equal to 20 minutes, preferably less than or equal to 10 minutes, preferably less than or equal to 5 minutes.

[0154] Optional heating step d2)

[0155] The process according to the invention may optionally comprise during step d) a heating step (d2) by heating all or part of the mixture present during solubilization, prior to separation step d3).

[0156] Preferably, if a heating step d2) is carried out, all of the mixture present during the solubilization is heated before the separation step d3).

[0157] If heating step d2) is carried out, the mixture is heated to a temperature of 250 to 450°C, preferably 250 to 400°C, more preferably 300 to 400°C.

[0158] This step d2) achieves a thermal range that promotes the separation of the soluble and insoluble fractions under gravity by varying the sedimentation constant and the density of the medium.

[0159] The heating step may be performed by direct heating or indirect heating (eg, by heat exchange).

[0160] The heating step may be performed in the solubilization reactor(s), or in one or more reactors downstream of the solubilization reactor(s).

[0161] On leaving the optional heating step d2), the heated mixture is referred to as mixture M6'.

[0162] Separation step d3)

[0163] The method according to the invention comprises a separation step d3) for separating at least part of the mixture obtained after the solubilization step d1) and, where appropriate, after the heating step d2) to obtain a mixed stream M4 enriched in soluble substances and a mixed stream M3 lean in soluble substances.

[0164] Within the meaning of the present invention, the term "mixed stream enriched in soluble substances" refers to a mixed stream which contains a higher weight proportion of soluble substances than the weight proportion of soluble substances in the mixture M2.

[0165] Within the meaning of the present invention, the term "mixed stream poor in soluble substances" refers to a mixed stream containing soluble substances in a lower weight proportion than in the mixture M2.

[0166] The soluble material refers to the material obtained after filtering through a 40 μm filter (not retained by the 40 μm filter) and then drying the initial material.

[0167] According to one embodiment, the ratio between the concentration of soluble substances in the mixture stream M4 enriched in soluble substances and the concentration of soluble substances in the mixture M2 is greater than or equal to 2, preferably greater than or equal to 5.

[0168] The separation step d3) can be carried out in the reactor of step d).

[0169] Thus, according to one embodiment, the separation step d3) can be carried out in the same reactor as the solubilization step d1).

[0170] Alternatively, the separation step d3) can be carried out in a separate separation device comprising a supply line for supplying the mixture M6 from step d1) or, where appropriate, the mixture M6' from step d2) and two outlet lines: (i) an outlet line for extracting a mixed stream M3 poor in soluble substances and (ii) an outlet line for extracting a mixed stream M4 rich in soluble substances.

[0171] The separation device may be a gravity separation device or a hydraulic separation device, such as a cyclone separator, typically equipped in the lower part with a discharge system operating continuously or intermittently or by filtration.

[0172] According to an advantageous embodiment, step d) is carried out in a reactor capable of achieving a differentiation in the residence time between the solid part (rich in insoluble matter) and the liquid part (rich in soluble matter).

[0173] This differentiation of the residence time can be achieved, for example, by providing a filter in the reactor of step d) which allows the passage of liquids but blocks the passage of solids.

[0174] This differentiation of residence time can simultaneously minimize the residence time of the liquid to avoid the formation of recombinant products, while allowing the unsolubilized material to have a longer residence time in the reactor of step d) to further solubilize it.

[0175] According to one embodiment, the reactor of step d) comprises an outlet for discharging a mixed stream M3 lean in soluble matter.

[0176] Thus, the method achieves separation of solubilized material from unsolubilized material by step d).

[0177] Typically, the separation step is achieved by controlling the mass residence time, preferably by controlling the residence time of soluble material.

[0178] Thus, according to an advantageous embodiment, the separation step comprises extracting a mixed stream M4 enriched in soluble matter and subsequently extracting a mixed stream M3 depleted in soluble matter, preferably through two different outlets. In particular, the residence time of the insoluble matter will be controlled.

[0179] The extraction of the mixed stream M3 can be carried out through continuous or discontinuous (eg sequential) outlets, so that the residence time of the insoluble substances is greater than the residence time of the soluble substances.

[0180] The extraction of the mixed stream M4 can be controlled depending on the input of the stream M2.

[0181] For example, if the reactor comprises two outlets, preferably a mixed stream M4 rich in soluble substances is extracted from the outlet of the upper part of the reactor, and a stream M3 poor in soluble substances is extracted from the outlet of the lower part of the reactor.

[0182] Preferably, the outlet at the upper part of the reactor is higher than the inlet, and the outlet at the lower part of the reactor is lower than the inlet.

[0183] According to one embodiment, heat is recovered from the soluble matter-rich mixture stream M4 obtained in step d), and the recovered heat is preferably used to at least partially heat the mixture M1p during step c) and / or at least partially heat the mixture M1 during step a).

[0184] Preferably, this heat recovery is carried out by heat exchange between the mixed stream M4 enriched in soluble substances obtained in step d) and the mixture M1p and / or M1.

[0185] According to one embodiment, at least one additive is added to the mixed stream M3 poor in soluble matter obtained in step d). According to one embodiment, said additive is added to the mixed stream M3 in a recovery reactor located downstream of the outlet of the mixed stream M3.

[0186] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air or permanganates (e.g. potassium permanganate), or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline agents such as KOH, NaOH, KHCO3, K2CO3, CaO, Ca(OH)2, CaCO3, Ca(HCO3)2, Mg(OH)2, MgO. Or from ammonia solutions such as ammonium hydroxide or ammonium chloride, or from mixtures of these agents.

[0187] When a reclaimer is used, the residence time can be set so that precipitation of the target salt can be achieved by adding the additive.

[0188] According to one embodiment, the mixture M1 contains phosphorus and the mixed stream M3 lean in soluble matter from step d) contains at least 70% by weight of the total amount of phosphorus in the mixture M1. In other words, at least 70% of the phosphorus in the mixture M1 is recovered in the mixed stream M3 lean in soluble matter obtained in step d).

[0189] According to one embodiment, this mixture M1 contains phosphorus and the mixed stream M3 poor in soluble matter obtained from step d) also contains phosphorus, preferably in a content ranging from 1% to 20% by dry weight relative to the total dry weight of the mixed stream M3 poor in soluble matter from step d).

[0190] According to one embodiment of the method, at least one first additive is added to the mixture M before step d), and at least one second additive is added to the mixed stream M3 lean in soluble matter obtained in step d), the first additive preferably being different from the second additive.

[0191] Thus, the mixture M upstream of step d) may be:

[0192] - the mixture M1 upstream of step a),

[0193] - the mixture M1 during step a),

[0194] - the mixture M1h upstream of step b),

[0195] - the mixture M1p upstream of step c),

[0196] - the mixture M1p during step c), or

[0197] - A mixture M2 downstream of step c) and upstream of step d).

[0198] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air or permanganates (e.g. potassium permanganate), or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline agents such as KOH, NaOH, KHCO3, K2CO3, CaO, Ca(OH)2, CaCO3, Ca(HCO3)2, Mg(OH)2, MgO. Or from ammonia solutions such as ammonium hydroxide or ammonium chloride, or from mixtures of these agents.

[0199] Cooling and decompression step e)

[0200] The method according to the present invention comprises cooling and depressurizing at least a part, preferably all, of the mixed stream M4 rich in soluble substances obtained in step d) to obtain a cooled and depressurized mixed stream M5.

[0201] The mixed stream M5 is a liquid stream, optionally comprising an insoluble gas fraction.

[0202] According to one embodiment, the mixed stream M4 rich in soluble substances is cooled to a temperature lower than or equal to 60° C., preferably lower than or equal to 40° C., before being depressurized.

[0203] The cooling may be carried out by means of a cooling device selected from a heat exchanger, a flasher or a scrubber, optionally integrated or not integrated into a rankine cycle.

[0204] According to one embodiment, the cooled mixed stream M4 is decompressed in a decompression device to a pressure of 1 to 10 bar. A cooled and decompressed mixed stream M5 is obtained. This decompression step allows the pressure to be reduced before injection into the digester, which is a device generally at a low overpressure (less than 1 relative bar).

[0205] According to this embodiment, the cooled and depressurized mixed stream M5 is fed to a digestion unit.

[0206] After decompression and before digestion, a gaseous portion that may be present and has become insoluble due to the decompression can be separated from the mixed stream M5 and recovered specifically so that at least a portion of it can be fed to a digester, for example through an inlet other than that of the mixed stream M5, or to another device.

[0207] As described during the heating phase, the mixed stream M4 can partially or completely heat the stream M1p during the heating step c) and / or heat the mixed stream M1 during step a).

[0208] When a sufficiently high heating rate is required, the mixed flow M4 heats only a part of the mixed flow M1p, the other part of the mixed flow M1p can be heated by another fluid during step c), and in this case, the mixed flow M4 is generally not fully cooled, and the cooled flow is called mixed flow M4'.

[0209] In this case, the residual heat of the mixed stream M4' can be used to heat the mixed stream M1 during the hydrolysis step, for example by decompressing the mixed stream M4' to 2-10 bar, the decompression steam thus being able to heat the mixed stream M1 in this case by direct injection.

[0210] According to this embodiment, the heating step c) is carried out partly in a heat exchanger which makes it possible to partially heat the mixed stream M1p and partially cool the mixed stream M4 obtained in step d).

[0211] According to this embodiment, the partially cooled mixed stream M4' is further cooled by reducing the pressure in a cooling device, thereby generating steam which can subsequently be injected into the hydrolysis reactor of step a).

[0212] If necessary, the cooled mixed stream M4' can be subjected to a second cooling downstream of the first cooling, for example by dilution with water or by heat exchange with a heat sink to reach a temperature less than or equal to 60°C, preferably less than or equal to 40°C.

[0213] Thus, the cooling step may be performed in one or more cooling devices connected in series.

[0214] According to one embodiment, the method of the present invention further comprises a separation step e') of separating at least a portion of the mixed stream M5 obtained in step e) to obtain a gaseous portion FG and a liquid stream M5'. According to this embodiment, the digestion step f) preferably digests at least a portion, preferably all, of the liquid stream M5'.

[0215] Digestion stage f)

[0216] The method according to the invention comprises at least one digestion step, preferably an anaerobic digestion step. Anaerobic digestion after a process for hydrolysis and separation of inorganic materials can, for example, increase the biogas yield relative to standard digestion, since organic polymers of the lignin or cell wall type have been solubilized and broken into shorter chains that are more easily digested, and there is less competition between methanogenic bacteria and inorganic reducing bacteria.

[0217] The digestion step f) is carried out in a digestion unit.

[0218] In step f), the digestion unit feed comprises at least a part of the mixed stream M5 obtained in step e), preferably the whole mixed stream M5, and / or, when step e') is present, the feed also comprises at least a part of the liquid stream M5' obtained in step e'), preferably the whole liquid stream M5'.

[0219] According to the embodiment in which the separation step e') is carried out, preferably, the digestion unit will be fed through at least two inlets, a first inlet for introducing the liquid stream M5' and a second inlet for introducing the gaseous portion FG.

[0220] Anaerobic digestion can be either mesophilic or thermophilic.

[0221] When mesophilic digestion is carried out, the temperature in the digester is 33°C to 37°C and the residence time is 16 to 22 days.

[0222] When thermophilic digestion is carried out, the temperature in the digester is 55°C to 60°C and the residence time is 10 to 12 days.

[0223] Residence time and temperature are two factors that influence the degradation of sludge and thus the optimization of energy production.

[0224] In the present invention, since the mixed stream to be digested is substantially liquid, the digestion process can be of UASB type and the residence time can be reduced.

[0225] At the end of digestion step f), biogas is obtained.

[0226] Such biogas typically comprises a mixture consisting essentially of methane, carbon dioxide and water. Biogas may also optionally contain other gases, such as hydrogen, oxygen, nitrogen or hydrogen sulfide, but the total amount of these other gases is usually less than 10% of the total weight of the biogas.

[0227] Possible M3 stream recycling steps

[0228] The mixed stream M3 poor in soluble matter resulting from step d) typically comprises organic and inorganic matter.

[0229] According to one embodiment, the method further comprises at least one step of recycling at least a portion of the mixed flow M3, said at least one recycling step being preferably chosen from a hydrothermal gasification step and a wet oxidation (OVH) step.

[0230] This additional step will allow the reuse of the organic matter still present in the mixed stream M3, while at the same time the reuse of the insoluble inorganic matter present in the mixed stream M3. Thus, the mixed stream M3, which in the methods of the prior art could be considered as non-recyclable waste, will produce recyclable by-products.

[0231] The process of the invention will therefore allow, on the one hand, excellent solubilization to ensure high-quality digestion and, on the other hand, conversion of the mixed stream M3 into a valuable resource.

[0232] Hydrothermal gasification (GH) is a thermal depolymerization process used to convert organic matter present in a moist medium into a mixture consisting only of small molecules at high to moderate temperatures and pressures.

[0233] In the hydrothermal gasification process, carbon and hydrogen of organic materials are thermochemically converted under quasi-critical or supercritical conditions. Part of the conversion is into water-soluble compounds of low molar mass.

[0234] The other part is converted into gaseous products such as carbon dioxide (CO2), methane (CH4), hydrogen (H2), carbon monoxide (CO), light hydrocarbons such as ethane (C2H6) and propane (C3H8).

[0235] While staying in the hydrothermal gasification reactor, when the temperature is below 400 °C, the organic matter undergoes, among other reactions, decomposition reactions based on hydrolysis, similar to the reactions that occur during liquefaction, but at a much faster rate. In fact, under quasi-critical or supercritical conditions, the unique properties of supercritical water as a solvent can be exploited, satisfying the conditions for solvation and homogeneous reactions, thus achieving very high reaction kinetic rates. Therefore, compared to conventional hydrolysis, hydrothermal gasification has much shorter residence times and much higher heating rates, limiting or even avoiding condensation and polymerization side reactions that lead to the formation of bio-oil and biochar.

[0236] When hydrothermal gasification is carried out at temperatures above 400 °C, free radical decomposition of the polymer dominates, especially reactions involving decarboxylation, deamination via C-N bond cleavage, and CC or CO cracking, while endothermic steam reforming is the main reaction pathway, converting small molecules containing 1 to 3 carbon atoms into carbon oxides and dihydrogens as well as nitrogen into ammonia.

[0237] Methane can also be produced by the methanogenesis reaction of CO and CO2 in the presence of hydrogen.

[0238] Therefore, hydrothermal gasification (GH) can be considered as a decomposition process that converts the organic residues in the mixed stream M3 into more easily biodegradable substances and ammonia dissolved in the liquid phase.

[0239] By adjusting the process conditions of the GH (in particular temperature, pressure and to a lesser extent residence time), it is possible to produce not only a gaseous fraction (synthesis gas) containing CH4, CO, CO2 and H2, but also an aqueous phase effluent which contains, on the one hand, predominantly easily digestible compounds, in particular carboxylic acids, and, on the other hand, ammonia in the form of ammonium salts of the produced carbonic acid.

[0240] It should be noted that GH differs from hydrothermal liquefaction (HTL), especially in terms of conversion and decomposition levels of organic matter, and HTL is less effective than GH even when GH is used under moderate temperature conditions.

[0241] Under HTL conditions, water still contains HO- and H3O+ ions that initiate the hydrolysis of organic matter.

[0242] The hydrolysis occurs only on the surface of the cellulose compounds in the organic part, and the solubility of these cellulose compounds in the subcritical environment is very low, resulting in a relatively low decomposition conversion rate.

[0243] Condensation reactions of intermediates (mainly including Aldol condensation, Friedel-Craft alkylation or acylation) are important reaction pathways leading to the formation of biocrude oil (also called bio-oil), which is an oil that can be used as a fuel, i.e., the biocrude oil contains organic molecules containing 5 or more carbon atoms, typically 8 to 16 carbon atoms. In contrast, the liquid products of GH mainly contain compounds that are easily biodegradable.

[0244] The difference between GH and pyrolysis is that GH is carried out in an aqueous medium, and the water is in a supercritical or quasi-critical state.

[0245] GH differs from "conventional" gasification of organic matter in that "conventional" gasification reduces the carbon / hydrogen mass ratio (C / H), which results in the formation of products with increased calorific value, including gases consisting primarily of syngas (a mixture of H2 / CO), bio-oils and / or carbonaceous solids (coke).

[0246] In the treatment method according to the present invention, the hydrothermal gasification step is generally carried out in a hydrothermal gasification reactor, and the feed at the inlet includes at least a part of the mixed flow M3, which part of the mixed flow M3 can come directly from step d), or can be pressurized and / or preheated and / or added with additives before entering the gasification reactor.

[0247] According to one embodiment, the gasification reactor is a tubular reactor.

[0248] Preferably, the hydrothermal gasification step is carried out at a temperature below 600°C, more preferably from 350°C to below 600°C, more preferably from 450 to below 600°C.

[0249] Preferably, the hydrothermal gasification step is carried out at a pressure greater than or equal to 220 bar, more preferably greater than or equal to 250 bar.

[0250] Preferably, the total residence time of the mixed stream M3 in the GH step is generally from 1 minute to 20 minutes, preferably from 2 minutes to 10 minutes, more preferably from 3 to 5 minutes.

[0251] According to a preferred embodiment, the hydrothermal gasification step is carried out in the presence of a catalyst. Preferably, the catalyst is selected from metals supported on activated carbon, such as ruthenium, nickel, palladium or platinum types. The catalyst can be located in the gasification reactor in the form of a solid particle bed.

[0252] Wet oxidation makes it possible to destroy organic matter while producing heat for heating step c) and acetic acid which can be sent to digestion step f).

[0253] The invention also relates to a device for carrying out the treatment method according to the invention.

[0254] Figures 1 to 3 The device according to the invention is shown without limiting its scope.

[0255] The device according to the invention comprises:

[0256] one or more hydrolysis reactors 1, optionally comprising a stirring device, connected at the inlet to a feed line of the mixture M1 to be treated, including a discharge line of the hydrolyzed mixture M1h, said one or more hydrolysis reactors 1 optionally being equipped with a grinding device at the front end, or with a recycling loop with a grinding device, or with a grinding device at the rear end, before the pump 3,

[0257] a pressure pump 3 connected at the inlet to the hydrolysis mixture M1h (optionally ground),

[0258] a heating device 4 comprising an inlet for introducing at least a portion of the mixture M1p and comprising at least one outlet for the mixture M2,

[0259] a reactor 5 comprising an inlet for introducing at least a portion of the mixture M2 coming from the heating device 4 and comprising at least two outlets, one for the mixed flow M3 and another for the mixed flow M4,

[0260] The reactor 5 may optionally include a heating device, and

[0261] the reactor 5 comprises separation means making it possible to extract a mixed stream M3 poor in soluble substances and a mixed stream M4 rich in soluble substances,

[0262] an optional heat exchanger 9 for recovering heat from the mixed flow M4 rich in soluble substances at the outlet of the reactor 5,

[0263] a pressure reduction device 10 , the inlet of which is supplied with at least a portion of the pre-cooled mixed flow M4 rich in soluble substances and which comprises an outlet for the mixed flow M5 ,

[0264] - an optional separation device 12, the inlet of which is supplied with at least a part of the mixed flow M5, and

[0265] comprising an outlet for the gaseous portion and an outlet for the liquid stream M5',

[0266] A digestion unit 11 , the inlet of which is supplied with at least a portion of the mixed stream M5 or, where appropriate, with at least a portion of the liquid stream M5 ′ and at least a portion of the gaseous portion.

[0267] Preferably, reactor 5 comprises one or more filters.

[0268] according to Figure 2 In one embodiment shown, the reactor 5 comprises:

[0269] a solubilization reactor 52 comprising an inlet for introducing at least a portion of the mixture M2 coming from the heating device 4 and also comprising an outlet line for the mixture M6,

[0270] an optional heating device 53 comprising an inlet for introducing at least a portion of the mixture M6 coming from the solubilization reactor 52 and also comprising an outlet line for the mixture M6',

[0271] A separation device 51 , fed with at least a portion of the mixture M6 or, when the heating device 53 is present, with at least a portion of the mixture M6 ′, and comprising at least two outlets, one for the mixed flow M3 and another for the mixed flow M4 .

[0272] According to one embodiment, the separation device 51 consists of one or more filters.

[0273] According to one embodiment, the heating device 4 is a heat exchanger for exchanging heat between the mixed flow M4 coming from the reactor 5 and the mixed flow M1p downstream of the booster pump 3 (and upstream of the reactor 5).

[0274] According to one embodiment, the heat exchanger 9 is able to recover the heat present in the mixed flow M4 and transfer it to the mixture M1 in the hydrolysis unit 1 or to the mixture M1 upstream of the hydrolysis unit.

[0275] Preferably, the heat exchanger 9 is located downstream of the heating device 4 and is able to recover the heat present in the mixed flow M4 ′.

[0276] Therefore, according to a preferred embodiment of the device, the pipeline of the mixed stream M4 downstream of the reactor 5 comprises, in sequence, a heat exchanger (corresponding to the heating device 4 ), a heat exchanger 9 and a pressure reducing device 10 .

[0277] According to one embodiment of the present invention, the pressure reducing device 10 comprises two outlets:

[0278] - a first outlet for the mixed stream to be fed to the digester 11, and

[0279] - A second outlet for steam, different from the first outlet.

[0280] According to this embodiment, the apparatus further comprises a steam delivery line for supplying steam from the second outlet of the pressure reducing device 10 to the supply line of the mixture M1 and / or to the hydrolysis reactor 1 .

[0281] According to one embodiment, the apparatus further comprises at least one injection device capable of injecting the additive into at least one element selected from:

[0282] - a conveying line for the mixture M1 upstream of the hydrolysis reactor 1,

[0283] - Hydrolysis reactor 1,

[0284] - a line for the mixture M1h downstream of the hydrolysis reactor 1 and the optional grinding device,

[0285] a line for the mixture M2 downstream of the heating device 4 and upstream of the reactor 5,

[0286] A line for the mixed stream M3 at the outlet of the reactor 5 (if necessary the separation device 51 ).

[0287] Figure 3An embodiment of the invention is shown in which the plant comprises a separation device 12 which is fed via a line from the mixed stream M5 of the device 10 and comprises an outlet for the gaseous portion FG and an outlet for the liquid stream M5'. Figure 3 In the embodiment shown, the gaseous portion FG coming from the separation device 12 is injected into the digester 11 through an inlet different from the inlet for the liquid stream M5 ′.

[0288] Therefore, according to one embodiment of the apparatus according to the invention, the digester 11 comprises two inlets:

[0289] a first inlet for introducing at least part of the liquid stream M5' coming from the separation device 12, and

[0290] A second inlet, different from the first inlet, for introducing at least a part of the gas fraction FG coming from the separation device 12 .

[0291] According to one embodiment of the present invention, the apparatus further comprises at least one recycling device arranged on the outlet pipeline of the mixed flow M3 downstream of the reactor 5, preferably selected from a hydrothermal gasification device or a wet oxidation device, and the recycling device is preferably located downstream of the additive injection pipeline (when present).

[0292] The device according to the invention may of course also comprise one or more of the features described in connection with the method according to the invention.

Claims

1. A method for treating a mixture M1 comprising at least organic matter, the method comprising: a). a hydrolysis step: hydrolyzing the mixture M1 at a temperature of 70°C to 165°C and a pressure of 1 to 8 bar to obtain a hydrolyzed mixture M1h, the ratio of the viscosity of the mixture M1 to the viscosity of the mixture M1h being at least 2, b) Pressurization step: pressurizing the mixture M1h to 20 to 350 bar to obtain a mixed flow M1p, c) Heating step: heating the mixed stream M1p obtained in step b) to a temperature of 250° C. to 450° C. to obtain a mixture M2, d). a solubilization step of solubilizing at least a portion of the mixture M2 obtained in step c), optionally a heating step of heating to a temperature of 250 to 450° C., and a separation step to obtain a mixture stream M4 rich in soluble substances and a mixture stream M3 poor in soluble substances, said step d) being carried out in one or more reactors with a total hydraulic retention time of less than or equal to 20 minutes, e) Cooling and decompression step: cooling and decompressing at least a portion of the mixed stream M4 rich in soluble substances obtained in step d) to obtain a mixed stream M5, f). Digestion step: digest at least a part of the mixed flow M5 obtained in step e).

2. The method according to claim 1 further comprises an additional separation step e') to separate at least a portion of the mixed flow M5 of step e) to obtain a gaseous portion FG and a liquid flow M5', and then subjecting at least a portion, preferably all, of the liquid flow M5' to a digestion step f) in a digester, wherein the gaseous portion FG is also introduced into the digester during the digestion step f).

3. The method according to claim 1 or 2, wherein the separation step comprises extracting a mixed stream M4 enriched in soluble matter and extracting a mixed stream M3 depleted in soluble matter, preferably through two independently controlled outlets.

4. The treatment method according to any one of claims 1 to 3, wherein the heating step c) comprises at least two sub-steps, at least one of the sub-steps being capable of heating the mixture M1p at a rate greater than or equal to 100°C / min, preferably greater than or equal to 200°C / min, more preferably greater than or equal to 400°C / min.

5. The processing method according to any one of claims 1 to 4, wherein: Heat is recovered from the mixed stream M4 enriched in soluble substances obtained in step d).

6. The processing method according to claim 5, wherein: Heat is recovered by heat exchange between the mixed stream M4 enriched in soluble substances obtained in step d) and the mixture M1p, preferably such heat exchange that it is possible to at least partially heat the mixture M1p during the heating step c).

7. The processing method according to any one of claims 1 to 6, wherein: During step e), the mixed stream M4 enriched in soluble substances is cooled to a temperature less than or equal to 60°C, preferably less than or equal to 40°C.

8. The treatment method according to any one of claims 1 to 7, wherein the cooling step comprises at least two sub-steps, preferably, the first sub-step is to obtain a cooled mixed stream M4' by performing heat exchange between the mixed stream M4 and the mixture M1p, and the second sub-step is to decompress the cooled mixed stream M4' to 2 to 10 bar to generate reduced pressure steam, and the reduced pressure steam can be optionally injected into the mixture M1 upstream of step a) or during step a).

9. The processing method according to any one of claims 1 to 8, wherein: The content of solid matter in the mixture M1 is 5% to 50% by weight, preferably 15% to 25% by weight, relative to the total weight of the mixture M1.

10. The treatment process according to any one of claims 1 to 9, wherein at least one additive is added to at least one mixed stream selected from: - a mixed stream M1 upstream of step a), - the mixture M1 during step a), - a mixed stream M1h upstream of step b), - the mixed confluence M1p upstream of step c), - the mixed flow M1p during step c), - the mixed stream during step d), - A mixed stream M3 poor in soluble substances obtained from step d).

11. The treatment process according to any one of claims 1 to 10, further comprising at least one recycling step of at least a portion of the mixed stream M3, the at least one recycling step preferably being chosen from a hydrothermal gasification step and a wet oxidation step.

12. An apparatus for implementing the treatment method according to any one of claims 1 to 11, comprising: at least one hydrolysis reactor (1), optionally comprising stirring means, fed at its inlet by a conveying line for the mixture M1 to be treated and comprising an outlet line for the hydrolysis mixture, said at least one hydrolysis reactor optionally being provided with a grinding device at the front end, or being equipped with a recycling circuit with a grinding device, or being provided with a grinding device at the rear end and upstream of the pump (3), a pressure pump (3) which is fed at its inlet with the hydrolysis mixture, optionally ground, and comprises an outlet line for the mixture M1p, - a heating device (4) comprising an inlet for introducing at least a portion of the mixture M1p downstream of the pump (3) and comprising at least one outlet for the mixture M2, a reactor (5) comprising an inlet for introducing at least a portion of the mixture M2 coming from the heating device (4) and comprising at least two outlets, one for the mixture flow M3 and the other for the mixture flow M4, The reactor (5) optionally comprises a heating device, and The reactor (5) comprises a separation device for extracting a mixed flow M3 poor in soluble substances and a mixed flow M4 rich in soluble substances, - an optional heat exchanger (9) for recovering the heat present in the mixed stream M4 rich in soluble substances at the outlet of the reactor (5), a pressure reducing device (10) supplied with at least part of the previously cooled mixed flow M4 rich in soluble substances and comprising an outlet for the mixed flow M5, an optional separation device (12) which is fed with at least a portion of the mixed stream M5 and comprises an outlet for the gaseous portion and an outlet for the liquid stream M5', A digestion unit (11) supplied with at least part of the mixed stream M5 or, where appropriate, with at least part of the liquid stream M5' and at least part of the gaseous fraction.

13. The device according to claim 12, characterized in that The reactor (5) comprises: a solubilization reactor (52) comprising an inlet for introducing at least a portion of the mixture M2 coming from the heating device (4) and comprising an outlet line for the mixture M6, an optional heating device ( 53 ) comprising an inlet for introducing at least a portion of the mixture M6 coming from the solubilization reactor ( 52 ) and comprising an outlet line for the mixture M6 ′, - A separation device (51) supplied with at least a portion of the mixture M6 or at least a portion of the mixture M6' when a heating device (53) is present and comprising at least two outlets, one for the mixed flow M3 and another for the mixed flow M4.

14. Apparatus according to claim 12 or 13, wherein the heating device (4) comprises a heat exchanger capable of exchanging heat between the mixed flow M4 rich in soluble substances from the reactor (5) and the mixed flow M1p downstream of the booster pump (3), thereby obtaining a cooled mixed flow M4'.

15. The device according to claim 14, characterized in that The plant also comprises a heat exchanger (9) arranged downstream of the heating device (4) and capable of recovering the heat present in the mixed flow M4' and transferring it to the mixture M1 for thermal hydrolysis, preferably by generating steam.

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