Method for treating complex waste

Abstract

The invention relates to a method for treating a mixture (M1), said method comprising: a) a pressurizing step of pressurizing the mixture (M1) to obtain a mixture (M1p), b) a heating step of heating the mixture (M1p) to obtain a mixture (M2), c) a separation step of separating the mixture (M2) to obtain a stream (M3) rich in inorganic substances and a stream (M4) lean in inorganic substances, d) a hydrothermal gasification step of subjecting at least part of the convection (M4) to hydrothermal gasification to obtain a mixture (M5) comprising gas and a liquid effluent, e) a cooling and separation step of cooling and separating the mixture (M5) in order to obtain a gas (M6) on the one hand and a liquid effluent (M7) on the other hand, the method further comprises at least one step of injecting at least one oxidizing agent into at least one stream selected from-at least part of the stream (M3) such that a stream (M3 ') can be obtained,-at least part of the stream (M4) such that a stream (M4') can be obtained, and-at least part of the liquid effluent (M7) such that a stream (M7 ') can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of treatment of complex wastes comprising organic and inorganic matter, such as aqueous wastes, digestion products of biological resources (biomass) and sewage sludge. Background Art

[0002] The processing of complex wastes requires high temperatures and therefore high energy costs.

[0003] Hydrothermal gasification is a process that generally aims to subject biomass to high temperatures and pressures. It therefore requires high energy consumption, in particular heat consumption.

[0004] In order to reduce the energy consumption of the process, there are systems for heat recovery of the heat from the output products of the reaction to preheat the input. However, these heat recovery systems face several problems:

[0005] Cost issues: The high quality steel surfaces required for these heat recovery systems result in very high costs.

[0006] ·Blocking problem: The exchanger is often blocked.

[0007] Thermal inhomogeneity issues: poor heat conduction of biomass leads to temperature dispersion within the waste.

[0008] • The “pinching” problem: these heat recovery systems cannot recover all the heat of the output product, since the temperature difference between the input product temperature and the output product temperature must be high enough to avoid an “infinite” exchanger.

[0009] • Furthermore, this clamping problem also occurs at supercritical temperature levels, because for these temperatures a slight increase in temperature results in a large difference in energy, so both the hot and cold product will have a region where the two products will be at close temperatures.

[0010] Furthermore, usually in order to heat up the residual temperature caused by clamping (when the temperatures of the two streams are too close, there is no good heat exchange), the generated gases are used to combust them and then recover the combustion heat.

[0011] The present invention proposes a method for treating complex wastes which better manages energy consumption, in particular heat consumption, throughout the process while maintaining a high waste reuse rate. Summary of the invention

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

[0013] a) a pressurization step: pressurizing the mixture M1 to a pressure of 150 to 350 bar to obtain a mixture M1p,

[0014] b) a heating step: heating the mixture M1p to a temperature of 200° C. to 500° C. to obtain a mixture M2,

[0015] c) separation step: separation of the mixture M2 to obtain a stream M3 rich in inorganic substances and a stream M4 poor in inorganic substances,

[0016] d) a hydrothermal gasification step of hydrothermally gasifying at least a portion of the stream M4 lean in inorganic matter to obtain a mixture M5 comprising a gaseous and liquid effluent,

[0017] e) a cooling and separation step: cooling and separation of the mixture M5 in order to obtain, on the one hand, a gas M6 and, on the other hand, a liquid effluent M7,

[0018] The method further comprises at least one injecting step of injecting at least one oxidant into at least one stream selected from:

[0019] at least a portion of the stream M3 rich in inorganic substances, preferably the entire stream M3, making it possible to obtain a stream M3',

[0020] at least a portion of the stream M4 depleted in inorganic matter, preferably the entire stream M4, making it possible to obtain a stream M4', and

[0021] - at least a portion of the liquid effluent M7, preferably the entire liquid effluent M7, making it possible to obtain a stream M7'.

[0022] According to one embodiment, the method of the invention further comprises at least one heat recovery step f): recovering heat present in at least one oxidation stream chosen from M3' or M7'.

[0023] According to one embodiment, the method of the present invention further comprises upstream of step a):

[0024] - a hydrolysis step of hydrolyzing the mixture M1 at a temperature ranging from 70°C to 165°C and a pressure ranging from 2 bar to 8 bar to obtain a mixture M1h, and / or

[0025] - Mechanical grinding step: The mixture M1 or M1h is subjected to mechanical grinding.

[0026] According to one embodiment, the method of the present invention further comprises at least one additional oxidant injection, wherein:

[0027] - in the mixture M1, and / or

[0028] - optionally in a mixture M1h, and / or

[0029] - optionally during the hydrolysis step in the mixture M1, and / or

[0030] - carried out upstream of step b) in the mixture M1p, and / or

[0031] - in the mixture M1p during step b), and / or

[0032] - is carried out upstream of step c) in the mixture M2.

[0033] According to one embodiment of the process according to the invention, the mixture M1 comprises 5 to 50% by weight of solid matter, preferably 15 to 25% by weight of solid matter, relative to the total weight of the mixture M1.

[0034] According to one embodiment of the process of the invention, the mixture M1 comprising at least organic matter also comprises phosphorus, and the stream M3 rich in inorganic matter produced in step c) therefore also comprises phosphorus, which is recovered with a yield of at least 70%.

[0035] According to one embodiment of the method of the present invention, the oxidant is selected from liquid oxygen, hydrogen peroxide, air, and permanganate, such as potassium permanganate.

[0036] According to one embodiment of the method according to the invention, the oxidizing agent is added in a stoichiometric ratio of 5% to 200% relative to the organic substance.

[0037] According to one embodiment, the method of the present invention comprises:

[0038] - a heat exchange between mixture M5 and mixture M1p, making it possible, on the one hand, to cool mixture M5 during step e) and, on the other hand, to heat mixture M1p,

[0039] - a step of injecting at least one oxidizing agent into the liquid effluent M7 in order to obtain an oxidized stream M7',

[0040] - a heat exchange between the oxidation stream M7' and the mixture M1, M1h or M1p, making it possible on the one hand to cool the oxidation stream M7' and on the other hand to heat the mixture M1, M1h or M1p, preferably M1p, during step b).

[0041] According to one embodiment, the method of the invention further comprises a digestion step: digesting at least a portion of the stream M7 or the stream M7" obtained by cooling the stream M7', preferably digesting at least a portion of the stream M7" obtained by cooling the stream M7'.

[0042] Preferably, the digestion step is anaerobic digestion.

[0043] Another subject of the present invention is a device for implementing the treatment method according to the invention, comprising:

[0044] a pressure pump fed by the mixture M1 or optionally by a hydrolyzed mixture, and comprising an outlet for the mixture M1p, wherein the hydrolyzed mixture has optionally been subjected to grinding,

[0045] - a heating device comprising an inlet capable of introducing at least a portion of the mixture M1p downstream of the pump,

[0046] a separation device fed by at least a portion of the heated mixture coming from the heating device and comprising an outlet for a stream M3 rich in inorganic matter and an outlet for a stream M4 lean in inorganic matter,

[0047] a hydrothermal gasification reactor fed by at least part of the stream M4 coming from the separation device and comprising an outlet for a mixture M5 comprising gas and liquid effluent,

[0048] a separation device located downstream of the gasification reactor, fed by at least a portion of the precooled mixture M5 and comprising at least one outlet for the gaseous effluent M6 and at least one outlet for the liquid effluent M7,

[0049] - at least one oxidant injection device located:

[0050] in a pipeline of a stream M3 rich in inorganic substances or in an oxidation reactor fed by the stream M3,

[0051] in the pipeline of stream M4, and / or

[0052] In the pipeline of flow M7.

[0053] According to one embodiment, the device of the present invention further comprises:

[0054] one or more hydrolysis reactors, optionally comprising stirring means and fed at the inlet by a supply line for the mixture M1 to be treated and comprising an outlet line for the hydrolyzed mixture M1h, and

[0055] - optionally a mechanical grinding device fed by the outlet line for the hydrolyzed mixture M1h and comprising an outlet line for the hydrolyzed and ground mixture,

[0056] - Optionally at least one device for exchanging heat between at least one of the streams M3 and / or M7 and at least one stream chosen from M1 , M1h, M1p or M2 downstream of the injection device.

[0057] According to one embodiment, the device of the present invention comprises:

[0058] - at least one means for injecting an oxidizing agent into the line of the stream M7 in order to obtain the oxidized stream M7', and

[0059] - heat exchange means for recovering heat from the mixture M5 and transferring it to the mixture M1p, and

[0060] - heat exchange means for recovering heat from the stream M7' and transferring it to the mixture M1, M1h or M1p,

[0061] Therein, one of the two heat exchange devices can be the same as the heating device.

[0062] The invention enables improved processing of organic matter in complex matrices. The improved processing allows better recycling of inorganic matter, such as salts, on the one hand, and of organic matter, on the other hand.

[0063] By means of the method according to the invention, on the one hand, a part of the organic matter is burned directly in the system to generate the required temperature in situ, thus consuming less carbon than in an external combustion system to obtain the same result, and on the other hand, this combustion will be finely controlled to control the temperature. Finally, this internal combustion will be combined with heat recovery while limiting costs due to the increase in viscosity and due to the movement of the clamping.

[0064] Furthermore, the hydrothermal conditions added to the oxidant enable this internal combustion reaction to occur.

[0065] Finally, in the hydrothermal gasification process, a separation step of the inorganic substances is carried out using supercritical conditions, which render the inorganic substances insoluble and thus recover them in a separate manner. However, the recovery of pure inorganic substances is technically complex. It is appropriate to discharge a large amount of water together with this inorganic substance, which is always associated with the unreacted organic substances.

[0066] By means of the process according to the invention, the injection of an oxidizing agent into the organic substance in various steps of the process makes it possible to release heat and obtain an inorganic residue which is purified from the organic substance and is therefore more reusable.

[0067] The configuration of the method proposed in the present invention makes it possible to integrate in an inventive way all the problems of the prior art identified by the inventors.

[0068] BRIEF DESCRIPTION OF THE DRAWINGS

[0069] [ Figure 1 ] is a schematic diagram of the processing method according to the present invention.

[0070] [ Figure 2 ] is a schematic diagram of the processing method according to the present invention.

[0071] [ Figure 3 ] is a schematic diagram of the processing method according to the present invention.

[0072] [ Figure 4 ] is a schematic diagram of the processing method according to the present invention.

[0073] [ Figure 5 ] is a schematic diagram of the processing method according to the present invention.

[0074] [ Figure 6 ] is a schematic diagram of the processing method according to the present invention.

[0075] [ Figure 7 ] is a schematic diagram of the processing method according to the present invention. DETAILED DESCRIPTION

[0076] The present invention relates to a method for treating a mixture M1 comprising at least organic matter, said method comprising:

[0077] a. a pressurizing step: pressurizing the mixture M1 to a pressure of 150 to 350 bar, preferably 200 to 250 bar, to obtain a mixture M1p,

[0078] b. a heating step of heating the mixture M1p to a temperature of 200°C to 500°C, preferably 250°C to 350°C, to obtain a mixture M2,

[0079] c. separation step: separation step b) to obtain a mixture M2 rich in inorganic substances and a stream M3 depleted in inorganic substances M4,

[0080] d. hydrothermal gasification step: hydrothermal gasification of at least a portion of the inorganic substance-poor stream M4, preferably hydrothermal gasification of the entire stream M4, to obtain a mixture M5 comprising a gas and liquid effluent,

[0081] e. Cooling and separation step: The mixture M5 is cooled and separated to obtain a gas M6 on the one hand and a liquid effluent M7 on the other hand,

[0082] The method further comprises at least one step of injecting at least one oxidant into at least one stream selected from the group consisting of:

[0083] at least a part of the stream M3 rich in inorganic substances, preferably the entirety of the stream M3,

[0084] at least a portion of the stream M4 depleted in inorganic matter, preferably the entirety of the stream M4,

[0085] - at least a part of the liquid effluent M7, preferably the entirety of the liquid effluent M7.

[0086] Typically, the addition of an oxidant to a stream is capable of producing an exothermic oxidation reaction in the stream, thereby producing an oxidized stream.

[0087] Therefore, according to one embodiment, the method according to the invention also comprises at least one recovery step f): recovery of the heat present in at least one oxidation stream (stream obtained after injection of an oxidizing agent) chosen from streams M3' or M7'.

[0088] According to a preferred embodiment, the method comprises at least one step of injecting an oxidizing agent into at least a portion of the stream M3 rich in inorganic substances, preferably into the whole of the stream M3, so as to obtain an oxidized stream M3'. Preferably, according to this embodiment, the method also comprises at least one step of recovering the heat released during the oxidation of the stream M3, so as to at least partially heat the mixture M1 upstream of the heating step b). Thus, it can be a mixture M1, M1h or M1p.

[0089] According to a preferred embodiment, the method comprises at least one step of injecting an oxidizing agent into at least a portion of the stream M7, preferably into the entire stream M7, so as to obtain an oxidized stream M7'. Preferably, according to this embodiment, the method also comprises at least one step of recovering the heat released during the oxidation of the stream M7', so as to at least partially heat the mixture M1 upstream of the heating step b). Thus, it can be a mixture M1, M1h or M1p.

[0090] Within the meaning of the present invention, the expression "at least a part of a mixture or a stream" has the same meaning as the expression "all or part of said mixture or stream". When it is a part of said mixture or said stream, the expression refers to a certain proportion of said mixture or said stream. For example, "every part of a mixture" or "every part of a stream" will have the same composition in the sense of this expression.

[0091] Therefore, within the meaning of the present invention, the expression "step X carried out on the entirety of the stream M produced in step y" means that steps X and y are continuous and that there is no intermediate separation step between steps X and y, it being understood that there may be a cooling / heating of the stream M between steps X and y, in particular by heat exchange, which heat exchange may optionally involve a stream exchange.

[0092] Mixtures containing at least organic matter M1

[0093] The mixture M1 contains at least organic substances. Typically, the mixture M1 also contains inorganic substances. Among the inorganic substances, salts containing anions such as phosphate, sulfate, chloride, carbonate and bicarbonate can be cited, with sodium, magnesium, calcium, ammonium and metals as counterions.

[0094] The mixture M1 can be selected, for example, from primary sludge, mixed sludge or biological sludge from municipal and industrial purification plants.

[0095] According to one embodiment, the mixture M1 comprises from 5% to 50% by weight of solid matter, preferably from 15% to 25% by weight of solid matter, relative to the total weight of the mixture M1.

[0096] Optional hydrolysis step

[0097] According to one embodiment, the method according to the invention comprises a step of hydrolyzing the mixture M1 , carried out upstream of the pressurization step a).

[0098] The hydrolysis step is carried out at a temperature of 70 to 165°C and a pressure of 2 to 8 bar.

[0099] The hydrolysis step enables the viscosity of the mixture to be reduced. The optional hydrolysis step thus enables a mixture M1h to be obtained, also called hydrolyzate.

[0100] The hydrolysis step is capable of degrading the organic matter, in particular it is capable of breaking chemical bonds and depolymerizing the organic matter through the action of water.

[0101] The mixture M1h generally has a viscosity which is at least one-half, preferably at least one-quarter, more preferably at least one-tenth of the viscosity of the mixture M1.

[0102] Thus, 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.

[0103] The viscosity defined in the context of the present invention is the viscosity measured at the same temperature (e.g. 20° C.) by using a rheometer suitable for the viscosity to be measured (cylinder-cylinder, plane-plane) and by measuring the viscosity at the same shear (in s -1 The kinematic viscosity is measured by measuring both viscosities in units of , while generally taking care to eliminate turbulence problems and to obey rheological rules (e.g., the spacing between cylinders depends on the particle size).

[0104] The hydrolysis step carried out on the mixture M1 can be carried out in one or more hydrolysis reactors connected in parallel or in series.

[0105] The hydrolysis step is capable of hydrolyzing the mixture M1, in particular by maintaining a mean hydraulic retention time at a desired temperature and pressure, preferably a temperature ranging from 70°C to 165°C and a pressure ranging from 2 to 8 bar, it being understood that if the hydrolysis step is carried out in a plurality of hydrolysis reactors, the temperature in the different reactors may be the same or different and similarly, the pressure in the different reactors may be the same or different.

[0106] Advantageously, the hydrolysis step will implement an internal energy recovery step, so that the heat consumption of the hydrolysis can be minimized. For example, there may be an energy recycling loop from the hot hydrolyzate to the cold product to be hydrolyzed, for example by generating expansion steam of the hot hydrolyzate and injecting it into the cold product to be hydrolyzed or heat exchange.

[0107] At the outlet of the hydrolysis step, a hydrolysate M1h is obtained which is not necessarily at the temperature and pressure required for the hydrolysis. In fact, before leaving the hydrolysis step, the hydrolysate may optionally undergo a cooling and / or expansion step.

[0108] In particular, for example, if the hydrolysis is carried out at high temperature (eg 100 to 165°C), it may be desirable to cool the hydrolysate, for example to a temperature below 90°C, so that stream M1h has a lower temperature for pressurization in step a) of the process of the invention.

[0109] The extraction of the hydrolysate M1h can be controlled by measuring the viscosity.

[0110] According to one embodiment, additives are added to the mixture M1 to be treated before entering the hydrolysis unit.

[0111] 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.

[0112] Steam can:

[0113] - upstream of the hydrolysis, into the inlet of a mixer of the dynamic mixer type, and / or

[0114] - direct injection into the hydrolysis reactor, preferably tangentially at the bottom to avoid clogging with sludge, and / or

[0115] - Injection into the recirculation loop of hydrolyzed sludge.

[0116] According to one embodiment, during the hydrolysis, the mixture M1 is mixed, for example stirred.

[0117] The hydrolysis reactor may be a batch reactor, optionally with stirring.

[0118] Prior to pressing, the treatment process may optionally include a grinding step, preferably mechanical grinding.

[0119] When a grinding step is present, the step of grinding the mixture M1 can be carried out before, during or after the hydrolysis. In the latter case, the mixture M1h is ground.

[0120] When the process of the invention implements a hydrolysis step combined with a grinding step, then the process of the invention may optionally comprise a step of recycling at least a portion of the ground hydrolysate to the inlet of the hydrolysis step.

[0121] According to one embodiment, the hydrolysis reactor comprises a recirculation loop equipped with grinding means capable of introducing at least a portion of the hydrolysate into said grinding means and returning at least a portion, preferably all, of the hydrolysate thus ground to the inlet of the hydrolysis step.

[0122] 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.

[0123] The particle size "less than X μm" means that 95% of the solid particles are retained in a square mesh sieve of X μm, and the remaining 5% of the particles have a size no greater than 3 times X μm.

[0124] Besides the particle size reduction which enables to minimize downstream blockages, the grinding step also enables to homogenize the mixture M1 and to reduce the viscosity, which will enable to better control the process parameters of the hydrothermal gasification operation.

[0125] As with the hydrolysis step, grinding and particle size reduction also aid in homogenization of the biomass.

[0126] In reactors using high pressures, mechanical stirring is difficult to carry out, and the reduction in viscosity due to the hydrolysis step can also improve the internal turbulence and thus the homogenization in the pressurized reactor.

[0127] Pressurization step a)

[0128] The method according to the invention comprises a step of pressurizing the mixture M1, if appropriate the hydrolyzed mixture M1 (which is now referred to as mixture M1h), at a pressure of 150 to 350 bar, preferably 200 to 250 bar.

[0129] Pressurization is carried out upstream of the heating step b) in order to avoid evaporation of the mixture.

[0130] For the pressurization step, when a hydrolysis reactor is present, a pump may be provided on the pipeline at the outlet of the hydrolysis reactor.

[0131] In another embodiment, a pump provided for this purpose pressurizes the booster pump.

[0132] In the context of the present invention, the expression "if necessary M1h" means that this feature only applies if a hydrolysis step is present, since if no hydrolysis step is carried out, stream M1h does not exist.

[0133] Heating step b)

[0134] The method according to the invention comprises a step of heating the mixture M1 to a temperature ranging from 200 to 500°C, preferably from 250 to 350°C.

[0135] According to one embodiment of carrying out the hydrolysis step, the heating step is preferably carried out downstream of the pressurization step.

[0136] According to one embodiment of carrying out the grinding step, said heating step is preferably carried out downstream of the pressing step.

[0137] At least part of the heating of the mixture M1 (or M1h, if hydrolyzed) can be carried out in a heat exchanger, for example by using heat recovered during step f) of recovering heat from at least one oxidation stream.

[0138] Thus, there may be a heat exchanger (downstream of the booster pump) configured to recover the heat released during the oxidation step after addition of at least one oxidizing agent and to heat the mixture M1 or M1h if a hydrolysis step is present, before the separation step c).

[0139] According to one embodiment, an oxidizing agent is also added to at least one flow selected from the mixture M1, optionally M1h, the mixture M1p and the mixture M2.

[0140] According to one embodiment, the oxidant is selected from oxidation reactants, such as liquefied oxygen, hydrogen peroxide, air, permanganate, such as potassium permanganate.

[0141] Separation step c)

[0142] The method according to the invention comprises a separation step of separating the mixture M2 resulting from step b) so as to obtain a stream M3 rich in inorganic substances and a stream M4 poor in inorganic substances.

[0143] Within the meaning of the present invention, the term "stream rich in inorganic substances" means a stream comprising a weight proportion of inorganic substances greater than that in the mixture M2.

[0144] Within the meaning of the present invention, the term “stream depleted in inorganic substances” means a stream comprising a weight proportion of inorganic substances which is less than the weight proportion of inorganic substances in the mixture M2 .

[0145] According to one embodiment, the ratio between the concentration of inorganic substances in the stream M3 rich in inorganic substances and the concentration of inorganic substances in the mixture M2 is at least 2, preferably at least 5.

[0146] This separation step is generally carried out in a separation device comprising a supply line for the mixture M2 resulting from step a) and two output lines: (i) a line for extracting a stream M3 rich in inorganic substances and (ii) a line for extracting a stream M4 poor in inorganic substances.

[0147] The separation device may be a hydraulic separation device of the cyclone type or a gravity separation device, usually equipped with a continuous or intermittently operated discharge system at the bottom.

[0148] According to one embodiment, the mixture M1 contains phosphorus and the inorganic-rich stream M3 produced in step c) contains at least 70% by weight of the total weight of phosphorus present in the mixture M1. In other words, at least 70% by weight of the phosphorus present in the mixture M1 is recovered in the inorganic-rich stream M3 produced in step c).

[0149] According to one embodiment, the mixture M1 contains phosphorus and the stream M3 rich in inorganic matter produced in step c) contains phosphorus in a proportion preferably ranging from 1% to 20% by dry weight relative to the total dry weight of the stream M3 rich in inorganic matter produced in step c).

[0150] Oxidant injection

[0151] The treatment method according to the invention comprises at least one step of injecting at least one oxidizing agent.

[0152] According to one embodiment, the at least one oxidizing agent is especially chosen from liquid oxygen, hydrogen peroxide, air, permanganates, such as potassium permanganate.

[0153] The injection can be done directly in the flow line or in the oxidation reactor, preferably the oxidant is injected directly into the flow line and the oxidation is preferably done directly in-line (without specific means of oxidation reactor type).

[0154] When an oxidation reactor is used, the oxidant may be injected into a flow line upstream of the reactor or into the reactor. According to this embodiment, the residence time in the oxidation reactor may be from 1 to 300 seconds.

[0155] In general, the amount of oxidant can be adjusted depending on the goal of the oxidation. Thus, if the oxidation is for heating, the amount of oxidant can be adjusted depending on the desired temperature. If the oxidation is for breaking down organic matter and producing minerals that do not contain organic matter, then the oxidant is used in excess and there is no need to control the excess amount. If the oxidation is for making organic matter more digestible, the amount of oxidant can be adjusted depending on the digestibility of the effluent, which is measured in terms of the amount of total organic carbon (COT, i.e., total organic carbon) that can be measured downstream of the digestion process.

[0156] Preferably, the oxidizing agent is added to at least one stream selected from the stream M3, the stream M4 and the stream M7 in a stoichiometric proportion of 5% to 200% relative to the organic matter.

[0157] Oxidation allows for better management of energy resources when heat recovery is performed.

[0158] In addition to the above-mentioned oxidant injections, the method according to the invention may also comprise one or more further oxidant injections.

[0159] Therefore, according to one embodiment, the method further comprises at least one injection of an oxidant into at least one stream selected from:

[0160] - a flow of mixture M1, and / or

[0161] - during the optional hydrolysis step of mixture M1, and / or

[0162] - a stream of the mixture M1h downstream of the optional hydrolysis step, and / or

[0163] - a flow of the mixture M1p downstream of the pressurizing step a) and upstream of the heating step b), and / or

[0164] - the mixture M1p during heating step b), and / or

[0165] - a flow of the mixture M2 downstream of the heating step b) and upstream of step c),

[0166] Preferably selected from:

[0167] - a flow of mixture M1, and / or

[0168] - a stream of the mixture M1h downstream of the optional hydrolysis step, and / or,

[0169] a flow of the mixture M1p downstream of the pressurizing step a) and upstream of the heating step b), and / or

[0170] - A flow of mixture M2 downstream of the heating step b) and upstream of step c).

[0171] According to one embodiment, the method comprises injecting an oxidizing agent in at least a portion of the stream M3 rich in inorganic substances, preferably in the entire stream M3.

[0172] Preferably, the oxidizing agent is added to the stream M3 in a stoichiometric proportion ranging from 30% to 200% relative to the organic substance, preferably ranging from 100 to 200% relative to the organic substance.

[0173] The addition of an oxidizing agent makes it possible to oxidize the stream M3 so as to obtain an oxidized stream M3'.

[0174] When this oxidation is carried out on at least a portion of the stream M3 so as to obtain an oxidized stream M3 ′, this oxidation makes it possible in particular to remove the residual organic substances in order to obtain a stream of inorganic substances more easily recyclable.

[0175] Oxidation makes it possible to “burn” the organic matter present together with the minerals in the stream M3 , which then makes it possible to obtain a more “mineral” stream which can then be separated more easily by precipitation / crystallization for example.

[0176] Therefore, according to one embodiment, a step of adding an additive to the oxidation stream M3' and a step of recovering the salt can be provided. For example, the additive can be a magnesium salt and the recovery step can be a struvite precipitation step. The magnesium salt can be selected from MgO, Mg(OH)2, MgCl2.

[0177] According to one embodiment, said oxidant injection step is carried out in at least a portion of the flow M4 lean in inorganic matter.

[0178] The addition of an oxidizing agent makes it possible to oxidize the stream M4 to obtain an oxidized stream M4'.

[0179] Such an oxidant injection makes it possible in particular to heat the stream M4 upstream of the hydrothermal gasification step d), which will allow to have a minimum reliance on external heat sources or heat exchanges and thus to reduce the size of the heat exchangers.

[0180] The proportion of the oxidant can be controlled, for example, by a target temperature after oxidation. Thus, a temperature sensor can be present in-line downstream of the oxidant injection point. Thus, the control unit can adjust the amount of injected oxidant based on the temperature measurement downstream of the oxidant injection point.

[0181] Preferably, the oxidizing agent is added to the stream M4 in a stoichiometric proportion ranging from 5% to 50% relative to the organic substance, preferably ranging from 5% to 20% relative to the organic substance.

[0182] According to one embodiment, said oxidant injection step is performed in at least a portion of the liquid effluent M7.

[0183] This injection of oxidizing agents is particularly capable of destroying undesirable compounds that resist digestion and thus making a portion of indigestible molecules digestible. Organic matter is said to be "resistant to digestion" if it cannot be broken down by bacteria via aerobic biological pathways within a residence time of 20 days.

[0184] Moreover, such an injection will allow increasing the temperature of this stream M7 and thus better heating of the mixture M1 , M1h, M2 during the optional heat recovery step.

[0185] Furthermore, since stream M7 is cooler than stream M5, injecting the oxidant into stream M7 instead of stream M5 avoids too high a temperature increase (and thus reduces stress on the plant) and makes it possible not to burn CH4 produced in the GH.

[0186] Therefore, the hydrothermal gasification step (followed by cooling and separation steps) combined with the step of injecting an oxidant into the downstream liquid stream (stream M7) allows to achieve better thermal and process management of the material to promote possible subsequent digestion.

[0187] Preferably, the oxidizing agent is added to the stream M7 in a stoichiometric proportion ranging from 5% to 100% relative to the organic matter, preferably ranging from 20% to 90% relative to the organic matter.

[0188] The addition of an oxidizing agent makes it possible to oxidize the stream M7 so as to obtain an oxidized stream M7'.

[0189] When used in mixtures M1 , M1h, M1p or M2, the injection of the oxidant enables heating of the substances with minimal use of heat exchange, thus optimizing energy consumption and the size of the exchanger.

[0190] According to this embodiment (addition of an oxidant in at least one of the streams M1 , M1h, M1p or M2), preferably, the oxidant is chosen in particular from liquid oxygen, hydrogen peroxide, air, permanganates such as potassium permanganate.

[0191] Preferably, the oxidizing agent is added to at least one of the streams M1 or M1h or M1p (before, during or after heating step b)) and M2 in a stoichiometric proportion ranging from 5% to 50% relative to the organic matter, preferably ranging from 5% to 20% relative to the organic matter.

[0192] According to one embodiment, the residence time of the oxidant in the stream under consideration (M1, M1h, M1p, M2, M3, M4 and / or M7) is generally between 1 second and 5 minutes.

[0193] Hydrothermal gasification step d)

[0194] The treatment method according to the invention comprises a step of hydrothermal gasification of the stream M4 lean in inorganic matter in order to obtain a gas and a stream comprising inorganic and organic matter.

[0195] Hydrothermal gasification (GH) is a thermal depolymerization process for converting organic matter present in a moist medium into a mixture containing only small molecules at high to moderate temperatures and pressures.

[0196] In the GH process, carbon and hydrogen of organic substances are converted thermochemically under quasi-critical or supercritical conditions. Part of the conversion is into water-soluble low-molar-mass compounds.

[0197] 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).

[0198] During residence in the hydrothermal gasification reactor at temperatures below 400 ° C, the organic matter undergoes, among other reactions, a decomposition based on hydrolysis, similar to the reactions occurring during liquefaction, but at a much faster rate. In fact, implementation under quasi-critical or supercritical conditions makes it possible to use the unique properties of supercritical water as a solvent, which allows to achieve homogeneous reaction and solvation conditions, leading to very high reaction kinetic rates. Thus, much shorter residence times and much higher heating rates are used compared to conventional hydrolysis, limiting or even avoiding secondary reactions of condensation and polymerization leading to the formation of bio-oil and biochar.

[0199] When GH is carried out at temperatures above 400°C, free radical decomposition of the polymer (particularly involving decarboxylation, deamination via C-N bond cleavage, and CC or CO cracking reactions) dominates, while endothermic steam reforming is the main reaction pathway for converting small molecules containing 1 to 3 carbon atoms into carbon oxides and hydrogen, and nitrogen into ammonia.

[0200] Methane is also produced by methanation of CO and CO2 using hydrogen.

[0201] Therefore, GH can be considered as a decomposition process that transforms the organic residues in stream M4 into more easily biodegradable substances and ammonia dissolved in the liquid phase.

[0202] The treatment conditions of GH (in particular temperature, pressure and, to a lesser extent, residence time) can be adjusted so as to produce not only a gaseous fraction (synthesis gas) containing CH4, CO, CO2 and H2, but also an aqueous effluent which contains, on the one hand, predominantly easily digestible compounds, in particular carboxylic acids, and, on the other hand, predominantly ammonia in the form of ammonium salts of the produced carbonic acid.

[0203] It should be noted that GH is different from hydrothermal liquefaction (HTL), in particular because the conversion and decomposition levels of organic matter in HTL are not as high as in GH, even when GH is used under moderate temperature conditions.

[0204] Under HTL conditions, water still contains HO- and H3O+ ions that initiate the hydrolysis of organic matter.

[0205] The hydrolysis takes place only on the surface of the cellulose compound contained in the organic fraction which dissolves very little in the subcritical medium, giving a rather low decomposition conversion.

[0206] The condensation reaction of the intermediates (mainly including aldol condensation, Friedel-Craft alkylation or acylation) is an important reaction pathway leading to the formation of biocrude oil, which is an oil that can be used as a fuel (also called bio-oil), i.e., the biocrude oil contains organic molecules containing 5 or more carbon atoms (usually 8 to 16 carbon atoms). On the other hand, the liquid products of GH mainly contain compounds that are easily biodegradable.

[0207] GH differs from pyrolysis in that it is carried out in an aqueous medium, with the water being in a supercritical or quasi-critical state.

[0208] GH differs from "conventional" gasification of organic matter in that "conventional" gasification reduces the carbon / hydrogen mass ratio (C / H), which results in products with increased calorific value, including gases consisting primarily of syngas (a mixture of H2 / CO), bio-oils and / or carbonaceous solids (char).

[0209] The presence of an oxidant introduced into one of the streams M1, M1h, M1p, M2, M3, M4, M7 creates an exothermic combustion mechanism, even starting from subcritical conditions, thereby accelerating the decomposition reaction and generating excess heat, which is able to increase the temperature of the medium faster than heating by heat exchange.

[0210] In the treatment method according to the invention, the hydrothermal gasification step is generally carried out in a hydrothermal gasification reactor supplied at an inlet with a stream M4 lean in inorganic matter and comprising an outlet for a mixture M5 comprising a gaseous and liquid effluent, the liquid effluent then generally comprising organic and inorganic matter.

[0211] According to one embodiment, the gasification reactor is a tubular reactor.

[0212] The gasification reactor may optionally include a catalyst. Preferably, the gasification reactor contains no catalyst.

[0213] Preferably, the hydrothermal gasification step is carried out at a temperature below 600°C, preferably at a temperature from 350°C to below 600°C, more preferably from 450 to below 600°C.

[0214] Preferably, the hydrothermal gasification step is carried out at a pressure greater than or equal to 220 bar, preferably greater than or equal to 250 bar.

[0215] Preferably, the (total) residence time of the stream M4 lean in inorganic matter in step e) of GH is generally between 1 minute and 20 minutes, preferably between 2 minutes and 10 minutes, more preferably between 3 and 5 minutes.

[0216] Cooling and separation step e)

[0217] The treatment method according to the invention comprises the steps of cooling and separating at least a portion of the mixture M5 resulting from the hydrothermal gasification of step d) so as to obtain a gaseous effluent M6 and a liquid effluent M7.

[0218] The cooling step enables the mixture M5 to reach a temperature less than or equal to 250°C.

[0219] If the process does not implement the injection of an oxidizing agent into the stream M7, according to a preferred embodiment, the cooling step will allow the mixture M5 to reach a temperature less than or equal to 200°C, preferably less than or equal to 120°C, more preferably between 50 and 120°C.

[0220] If the process implements at least one injection of an oxidizing agent into the stream M7, the cooling step will allow the mixture M5 to reach a temperature ranging from 180°C to 250°C, preferably from 190°C to 230°C, according to a preferred embodiment.

[0221] The cooling device may be selected from a heat exchanger, a flash evaporator, a scrubber, a Rankine cycle.

[0222] According to an advantageous embodiment, the cooling step is carried out by heat exchange, thus making it possible to at least partially heat the mixture M1p during the heating step b). According to this embodiment, the heating step b) and the cooling step d) are carried out in the same heat exchanger. Thus, the mixture M5 transfers heat to heat the mixture M1p.

[0223] According to one embodiment, the method does not comprise injecting an oxidant into flow M7 and, according to this embodiment, preferably, in addition to the heat exchange between mixture M5 and mixture M1p (corresponding to a first cooling step of cooling mixture M5), downstream of the first cooling step and upstream of the separation step of mixture M5 (to obtain flows M6 and M7), the method further comprises a second cooling step in a cooling device (preferably a heat recovery device).

[0224] According to one embodiment, the stream M5 (after cooling) is expanded in an expansion device to a pressure between 0 and 2 bar (relative). This expansion step makes it possible to recover, on the one hand, gases M6 and, on the other hand, liquid effluent M7. According to this embodiment, the liquid effluent resulting from the expansion can be used to feed the digestion unit.

[0225] Heat recoveryf)

[0226] The treatment method according to the invention optionally comprises at least one heat recovery step: recovering the heat released during the oxidation of at least one oxidation stream chosen from M3' or M7', in order to at least partially heat the mixture M1, if necessary M1h or M1p.

[0227] According to one embodiment, the heat recovery step f) is performed using a heat exchanger.

[0228] According to one embodiment, the heat recovery of step f) is carried out by direct heat exchange between the oxidation stream and the mixture M1 or M1h (if a hydrolysis has been carried out) or with the mixture M1p.

[0229] The term ‘direct heat exchange’ is the opposite of the term ‘indirect heat exchange.’ When a heat transfer fluid is used to recover heat from a ‘hot’ stream to transfer it to another ‘cold’ stream, the heat exchange will be termed indirect.

[0230] In contrast, when heat from a "hot" stream is transferred directly to a "cold" stream, without an intermediate heat transfer fluid, the heat exchange is said to be direct.

[0231] According to one embodiment, the heat recovery of step f) is carried out by indirect heat exchange between the oxidation stream M3' or M7' and the mixture M1, if necessary M1h or M1p, by means of a heat transfer circuit in which circulates an intermediate heat transfer fluid, which recovers the heat from the oxidation stream in order to transfer it to the mixture M1, if necessary M1h or M1p.

[0232] If the process is implemented with at least one injection of an oxidizing agent into the stream M7 , preferably, the oxidizing stream M7 ′ is then cooled, preferably by heat exchange with at least one stream used in the process.

[0233] According to one embodiment, before the optional digestion, the heat present in the stream M7 is recovered, the recovered heat preferably being able to at least partially heat the mixture M1, if necessary M1h, M1p, M2 and / or M4, preferably M1, if necessary M1h, M1p.

[0234] Preferably, this heat recovery is carried out by heat exchange between the stream M7 and the mixture M1 , M1h or M1p. Thus, the heat present in the stream M7 can be transferred to at least one stream selected from M1 , M1h, M1p.

[0235] According to one embodiment, an oxidant is added to the stream M7 before this heat exchange. In fact, the oxidation of the stream M7 will allow the stream M7 (called M7' after the oxidation) to be further heated and thus improve the heat exchange between the stream M7' and one of the streams selected from M1, M1h, M1p, M2, preferably M1 or M1h or M1p.

[0236] Preferably, after cooling the stream M7', for example by heat exchange as described above, the method further comprises (downstream of cooling M7') a step of separating the cooled stream M7', which step makes it possible to obtain CO2 on the one hand and stream M7". This separation step makes it possible to reduce the CO2 content present in the cooled stream M7' or even remove CO2. The stream M7", after the CO2 separation, can subsequently be used as input to a digester and undergo digestion.

[0237] According to an advantageous embodiment, the treatment method according to the invention comprises:

[0238] - a heat exchange between the mixture M5 and the mixture M1 or, if appropriate, M1h or M1p, which heat exchange makes it possible on the one hand to cool the mixture M5 (step e)) and on the other hand to heat the mixture M1 or M1h or M1p,

[0239] - a step of injecting at least one oxidizing agent into the liquid effluent M7 in order to obtain an oxidized stream M7',

[0240] - Heat exchange between the oxidation stream M7 ′ and the mixture M1 or, if applicable, M1h, M1p, which heat exchange makes it possible, on the one hand, to cool the stream M7 ′ and, on the other hand, to heat the mixture M1 or M1h or M1p.

[0241] According to an advantageous embodiment, the treatment method according to the invention comprises:

[0242] - a heat exchange between the mixture M5 and the mixture M1p which, on the one hand, makes it possible to cool the mixture M5 (step e)) to a temperature of 180° C. to 250° C. and, on the other hand, to heat the mixture M1p,

[0243] - a step of injecting at least one oxidizing agent into the liquid effluent M7 so as to obtain an oxidized stream M7' having a temperature comprised between 200°C and 350°C,

[0244] - heat exchange between the oxidation stream M7' and the mixture M1 or, if appropriate, M1h or M1p, which heat exchange can, on the one hand, cool the oxidation stream M7' to a temperature of less than or equal to 200° C., preferably less than or equal to 120° C., preferably less than or equal to 60° C., and on the other hand, heat the mixture M1 or M1h or M1p.

[0245] According to an advantageous embodiment, the treatment method according to the invention comprises:

[0246] - a heat exchange between the mixture M5 and the mixture M1 or, if appropriate, M1h or M1p, which heat exchange makes it possible on the one hand to cool the mixture M5 (step e)) and on the other hand to heat the mixture M1 or M1h or M1p,

[0247] - a step of injecting at least one oxidizing agent into the liquid effluent M3 in order to obtain an oxidized stream M3',

[0248] - Heat exchange between the oxidation stream M3 ′ and the mixture M1 , M1h, M1p, which heat exchange makes it possible, on the one hand, to cool the stream M3 ′ and, on the other hand, to heat the mixture M1 or M1h or M1p.

[0249] According to one embodiment, the processing method according to the present invention comprises:

[0250] - a heat exchange between mixture M5 and mixture M1p which makes it possible, on the one hand, to cool mixture M5 (step e)) to a temperature of 180° C. to 250° C. and, on the other hand, to heat mixture M1p,

[0251] - a step of injecting at least one oxidizing agent into the liquid effluent M7 so as to obtain an oxidized stream M7' having a temperature comprised between 200° C. and 350° C.,

[0252] - a step of injecting at least one oxidizing agent into the liquid effluent M3 in order to obtain an oxidized stream M3',

[0253] - heat exchange between the oxidation stream M3' and the mixture M1, M1h, M1p, which heat exchange makes it possible, on the one hand, to cool the stream M3' and, on the other hand, to heat the mixture M1 or M1h or M1p,

[0254] - heat exchange between the oxidation stream M7' and the mixture M1 or, if appropriate, M1h or M1p, which heat exchange can, on the one hand, cool the oxidation stream M7' to a temperature of less than or equal to 200° C., preferably less than or equal to 120° C., preferably less than or equal to 60° C., and, on the other hand, heat the mixture M1 or M1h or M1p.

[0255] The invention also relates to a device for carrying out the method according to the invention.

[0256] The device according to the invention comprises:

[0257] - optionally one or more hydrolysis reactors 1 , optionally comprising stirring means, which are fed at the inlet by a line for supplying the mixture M1 to be treated and which comprise an outlet line for the hydrolyzed mixture M1h,

[0258] - optionally a mechanical grinding device fed by the outlet line for the hydrolyzed mixture M1h and comprising an outlet line for the hydrolyzed and ground mixture,

[0259] a pressure pump 3 , which is fed by the mixture M1 or optionally by the hydrolyzed mixture (optionally ground) and comprises an outlet for the mixture M1p,

[0260] a heating device 4 comprising an inlet capable of introducing at least a portion of the mixture M1p downstream of the pump 3,

[0261] a separation device 5 fed by at least part of the heated mixture coming from the heating device 4 and comprising an outlet for a stream M3 rich in inorganic matter and an outlet for a stream M4 poor in inorganic matter,

[0262] a hydrothermal gasification reactor 8 fed by at least part of the stream M4 coming from the separation device 5 and comprising an outlet for a mixture M5 comprising gas and liquid effluent,

[0263] a separation device 9 situated downstream of the gasification reactor 8, fed by at least a portion of the precooled mixture M5 and comprising at least one outlet for a gaseous effluent M6 and at least one outlet for a liquid effluent M7,

[0264] - at least one oxidant injection device located:

[0265] in a pipeline of a stream M3 rich in inorganic substances or in an oxidation reactor fed by the stream M3,

[0266] in the pipeline of stream M4, and / or

[0267] In the pipeline of flow M7.

[0268] - Optionally means for exchanging heat between at least one of the streams M3' and / or M7' and at least one stream chosen from M1, M1h, M1p or M2 downstream of the injection means.

[0269] According to one embodiment of the invention, the apparatus comprises at least one hydrolysis reactor 1 upstream of a pressure pump 3 .

[0270] In practice, the plant according to the invention may comprise one or more hydrolysis reactors 1 connected in series or in parallel, fed at the inlet by a supply line for the mixture M1 and an outlet line for the hydrolyzed mixture M1h at a temperature lower than or equal to the hydrolysis temperature. The hydrolysis reactor 1 advantageously comprises heating and pressurizing means and optionally stirring means, and advantageously internal heat recovery means.

[0271] The hydrolysis reactor 1 can optionally be provided with a grinding device upstream thereof, or can be provided with a recirculation loop equipped with a grinding device, or can be provided with a grinding device downstream thereof upstream of the pump 3 .

[0272] The device according to the invention may also comprise, upstream of the separation device 9 , a cooling device 9 ′, which is fed by at least a portion of the mixture M5 .

[0273] According to one embodiment of the device, the heating means 4 is a heat exchanger capable of cooling the mixture M5 upstream of the separation means 9 or, when a cooling means 9 ′ is present, upstream of the cooling means 9 ′.

[0274] The plant according to the invention may optionally comprise a digestion unit fed by at least part of the stream M7" obtained after cooling of the stream M7'.

[0275] According to one embodiment, the device according to the invention comprises at least one device for injecting an oxidant into the line of stream M7 and into the cooling device 9 ′, and the heating device 4 is the same heat exchanger, so that the cooled stream M5 coming from said heat exchanger then feeds the separation device 9 .

[0276] According to one embodiment, the hydrolysis reactor is a heat exchanger capable of recovering heat from at least one of the oxidation flows M3 ′ and / or M7 ′ in order to transfer heat to the mixture M1 during the hydrolysis.

[0277] According to one embodiment, the plant also comprises at least one heat exchanger 10 , distinct from the heating means 4 , capable of recovering heat from at least one of the oxidation flows M3 ′ and / or M7 ′ in order to transfer heat to the mixture M1 p.

[0278] Figures 1 to 7 Each illustrates an embodiment of the method and the device according to the invention without limiting the scope thereof.

[0279] refer to Figure 1 Schematic diagram of the mixture M1, the mixture M1 is pressurized by a pump 3 before being introduced into a heating device 4 to obtain a mixture M2.

[0280] The mixture M2 is introduced into a separation device 5 in order to obtain a stream M3 rich in inorganic substances and a stream M4 poor in inorganic substances.

[0281] The stream M4 coming from the separation device 5 is introduced into a hydrothermal gasification reactor 8 in order to obtain a mixture M5 .

[0282] The mixture M5 can then be introduced into a cooling device 9 ′ and then separated in the separation device 9 in order to obtain a gas stream M6 and a liquid effluent M7 .

[0283] Figure 1 The device in FIG. 1 shows several oxidant injection points and thus also several injection means. It should be noted that the device according to the invention comprises at least one means for injecting an oxidant into at least one of the streams M3, M4 and / or M7 ( Figure 1 solid arrow in the figure).

[0284] The device according to the invention may also comprise at least one device for injecting an oxidant into at least one of the streams M1, M1p or M2 ( Figure 1 ).

[0285] Figure 2 An embodiment of the invention is shown in which the method comprises the injection of an oxidizing agent into the flow M3 and at least one heat recovery step in which heat is recovered from the oxidation flow M3 ′ by means of a heat exchanger 10 located downstream of the pump 3 and upstream of the heating device 4 .

[0286] The oxidation stream M3' can optionally be fed to a precipitation or crystallization reactor, after optionally adding additives, to selectively precipitate the product. For example, magnesium salts can be added to stream M3 to form struvite in a precipitation reactor.

[0287] Of course, in Figure 2 In the embodiment, it is possible to use, in particular Figure 1 In addition to the injection points shown in FIG. 1 , other oxidant injection points are set.

[0288] Figure 3 An embodiment of the invention is shown in which the method comprises the injection of an oxidizing agent into the stream M7 and at least one heat recovery step in which heat is recovered from the oxidizing stream M7' in a heat exchanger 10 downstream of the booster pump 3, thereby making it possible to heat the mixture M1p upstream of the heating device 4. According to this embodiment, the heating device 4 is a heat exchanger capable of cooling the mixture M5 (during step e)) and heating the mixture M1p during step b). According to this embodiment, the cooled mixture M5 is then introduced into the separation device 9. Also according to this embodiment, the cooled stream M7" downstream of the heat exchanger 10 is introduced into the digester 11. This embodiment in Figure 3 Shown in.

[0289] Of course, in Figure 3 In the embodiments, in particular Figure 1 In addition to the injection points shown in FIG. 1 , other oxidant injection points are set.

[0290] Figure 4 and Figure 1 The difference is that a hydrolysis reactor 1 is shown. Thus, according to one embodiment, the device comprises a hydrolysis reactor 1 fed by the mixture M1 and comprising an outlet for the hydrolyzate M1h. According to this embodiment, an oxidant may also be injected into the stream M1h.

[0291] Figure 5 An embodiment of the invention is shown in which the method comprises a preliminary step of hydrolyzing the mixture M1 in an upstream hydrolysis reactor 1 pressurized in a pump 3. Figure 5In the embodiment shown, the method comprises at least one injection of an oxidizing agent into the stream M3 to obtain an oxidized stream M3', and at least one step of recovering heat from the oxidized stream M3' to transfer it to the mixture M1 during the hydrolysis step, in which case the hydrolysis reactor 1 can be a heat exchanger.

[0292] Of course, in Figure 5 In the embodiments, it is possible to use, in particular Figure 4 In addition to the injection points shown in FIG. 1 , other oxidant injection points are set.

[0293] Figure 6 and Figure 5 The difference is that the heating device 4 is a heat exchanger capable of cooling the mixture M5 (during step e)) and heating the mixture M1p during step b). Figure 6 In the embodiment shown in FIG. 4 , the cooling step e) and the heating step b) are carried out in the heat exchanger 4. Figure 4 In the embodiment shown in , the device comprises cooling means 9 ′ downstream of the heat exchanger 4 to further cool the mixture M5 upstream of the separation device 9. This embodiment is particularly advantageous when the device does not comprise means for injecting an oxidant into the flow M7 downstream of the separation device 9.

[0294] According to this embodiment, therefore, the cooled mixture M5 is then introduced into the separation device 9 .

[0295] Figure 7 and Figure 6 The difference is that an oxidizing agent is injected into the stream M7 and the oxidizing stream M7 ′ is able to heat the mixture M1 during the hydrolysis step 1 . Also according to this embodiment, the cooled stream M7 ″ downstream of the heat exchanger 10 is introduced into the digester 11 .

[0296] The device according to the invention may of course comprise one or more of the features described in the context of the method according to the invention.

Claims

1. A method for treating a mixture M1 containing at least organic matter, the method comprising: a) a pressurization step: pressurizing the mixture M1 to a pressure of 150 to 350 bar to obtain a mixture M1p, b) a heating step: heating the mixture M1p to a temperature of 200° C. to 500° C. to obtain a mixture M2, c) separation step: separation of the mixture M2 to obtain a stream M3 rich in inorganic substances and a stream M4 poor in inorganic substances, d) a hydrothermal gasification step of hydrothermally gasifying at least a portion of the stream M4 lean in inorganic matter to obtain a mixture M5 comprising a gaseous and liquid effluent, e) a cooling and separation step: cooling and separation of the mixture M5 in order to obtain, on the one hand, a gas M6 and, on the other hand, a liquid effluent M7, The method further comprises at least one injecting step of injecting at least one oxidant into at least one stream selected from: at least a portion of the stream M3 rich in inorganic substances, preferably the entire stream M3, making it possible to obtain a stream M3', at least a portion of the stream M4 depleted in inorganic matter, preferably the entire stream M4, making it possible to obtain a stream M4', and - at least a portion of the liquid effluent M7, preferably the entire liquid effluent M7, making it possible to obtain a stream M7'.

2. The treatment process according to claim 1 further comprising at least one heat recovery step f): recovering heat present in at least one oxidation stream selected from M3' or M7'.

3. The processing method according to claim 1 or 2, further comprising upstream of step a): - a hydrolysis step of hydrolyzing the mixture M1 at a temperature ranging from 70°C to 165°C and a pressure ranging from 2 bar to 8 bar to obtain a mixture M1h, and / or - Mechanical grinding step: The mixture M1 or M1h is subjected to mechanical grinding.

4. A processing method according to claim 2 or 3, wherein: The at least one heat recovery step f) is carried out by means of a heat exchanger between the oxidation stream M3' or M7' and the mixture M1, M1h or M1p.

5. The process according to any one of claims 1 to 4, further comprising at least one additional oxidant injection, wherein: - in the mixture M1, and / or - optionally in a mixture M1h, and / or - optionally during the hydrolysis step in the mixture M1, and / or - carried out upstream of step b) in the mixture M1p, and / or - in the mixture M1p during step b), and / or - is carried out upstream of step c) in the mixture M2.

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

7. The processing method according to any one of claims 1 to 6, wherein: The mixture M1 comprising at least organic matter also comprises phosphorus, and the stream M3 rich in inorganic matter resulting from step c) therefore also comprises phosphorus, which is recovered with a yield of at least 70%.

8. The processing method according to any one of claims 1 to 7, wherein: The oxidant is selected from liquid oxygen, hydrogen peroxide, air, and permanganates, such as potassium permanganate.

9. The processing method according to any one of claims 1 to 8, wherein: The oxidizing agent is added in a stoichiometric ratio of 5% to 200% relative to the organic substance.

10. The processing method according to any one of claims 1 to 9, comprising: - a heat exchange between mixture M5 and mixture M1p, making it possible, on the one hand, to cool mixture M5 during step e) and, on the other hand, to heat mixture M1p, - a step of injecting at least one oxidizing agent into the liquid effluent M7 in order to obtain an oxidized stream M7', - a heat exchange between the oxidation stream M7' and the mixture M1, M1h or M1p, making it possible on the one hand to cool the oxidation stream M7' and on the other hand to heat the mixture M1, M1h or M1p, preferably M1p, during step b).

11. The treatment method according to any one of claims 1 to 10, further comprising a digestion step: digesting at least part of the stream M7 or the stream M7" obtained by cooling the stream M7', preferably digesting at least part of the stream M7" obtained by cooling the stream M7'.

12. The processing method according to claim 11, wherein: The digestion step is anaerobic digestion.

13. A device for implementing the treatment method according to any one of claims 1 to 12, comprising: a pressure pump (3) fed by the mixture M1 or optionally by a hydrolyzed mixture, and comprising an outlet for the mixture M1p, wherein the hydrolyzed mixture has optionally been subjected to grinding, a heating device (4) comprising an inlet capable of introducing at least a portion of the mixture M1p downstream of the pump (3), a separation device (5) fed by at least part of the heated mixture coming from the heating device (4) and comprising an outlet for a stream M3 rich in inorganic substances and an outlet for a stream M4 poor in inorganic substances, a hydrothermal gasification reactor (8) fed by at least part of the stream M4 coming from the separation device (5) and comprising an outlet for a mixture M5 comprising gas and liquid effluent, a separation device (9) located downstream of the gasification reactor (8), fed by at least a portion of the precooled mixture M5 and comprising at least one outlet for the gaseous effluent M6 and at least one outlet for the liquid effluent M7, - at least one oxidant injection device located: in a pipeline of a stream M3 rich in inorganic substances or in an oxidation reactor fed by the stream M3, in the pipeline of stream M4, and / or In the pipeline of flow M7.

14. The apparatus according to claim 13, further comprising: one or more hydrolysis reactors (1) which optionally comprise stirring means and which are fed at the inlet by a supply line for the mixture M1 to be treated and comprise an outlet line for the hydrolyzed mixture M1h, and - optionally a mechanical grinding device fed by the outlet line for the hydrolyzed mixture M1h and comprising an outlet line for the hydrolyzed and ground mixture, - Optionally at least one device (10) for heat exchange between at least one of the streams M3 and / or M7 downstream of the injection device and at least one stream chosen from M1, M1h, M1p or M2.

15. The device according to claim 13 or 14, comprising: - at least one means for injecting an oxidizing agent into the line of the stream M7 in order to obtain the oxidized stream M7', and - heat exchange means for recovering heat from the mixture M5 and transferring it to the mixture M1p, and - heat exchange means for recovering heat from the stream M7' and transferring it to the mixture M1, M1h or M1p, One of the two heat exchange devices can be the same as the heating device (4).

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