Method for treating complex waste

Abstract

The invention relates to a method for treating a mixture M1, said method comprising: a) a hydrolysis step of hydrolyzing the mixture M1 to obtain a hydrolyzed mixture M1h, b) pressurizing at least a portion of the hydrolyzed mixture M1h, c) a heating step of heating the mixture M1h to obtain a mixture M2, d) a first separation step of separating at least a portion of the mixture M2 to obtain a first stream M3 rich in inorganic substances and a first stream M4 lean in inorganic substances, e) a heating step of at least a portion of the first stream M4 lean in inorganic substances; f) a second separation step of separating at least a portion of the first stream M4 depleted of inorganic material to obtain a second stream M5 rich in inorganic material and a second stream M6 depleted of inorganic material, g) a hydrothermal gasification step of subjecting at least a portion of the second stream M6 depleted of inorganic material to hydrothermal gasification to obtain at least a stream M8 comprising gas and a liquid effluent.

Description

Technical Field

[0001] The invention relates to the field of treatment of complex wastes comprising organic and inorganic matter, such as wet biomass and biological waste, in particular industrial, food or agro-food waste, and also sewage sludge and sludge from purification plants. Background Art

[0002] Prior art methods attempt to process heterogeneous materials, ie materials containing both organic and inorganic matter, using a hydrothermal gasification type of process.

[0003] These hydrothermal gasification processes face many challenges, in particular when the waste of biological origin (e.g. wet biomass) is heterogeneous and / or when it has a high degree of dryness and / or when it has a low thermal conductivity. In fact, this type of process uses heat exchangers and due to the composition of this biomass, blockage phenomena of the exchangers may occur.

[0004] In the prior art of hydrothermal gasification, the efficient recovery of inorganic substances present in or resulting from the decomposition of heterogeneous biomass of this type remains a techno-economic challenge, since the separation is not selective enough to separately recover the various inorganic components (salts, oxides, metals, etc.). Therefore, the possible reuse of this inorganic part would require many post-processing steps and would become low-yielding and economically unprofitable.

[0005] Finally, prior art methods may generate significant heat consumption and may result in high construction costs.

[0006] In fact, when the biomass is inhomogeneous, has a high dryness and a low thermal conductivity, this leads to very large temperature gradients within the biomass matrix at the heat exchanger, resulting in undesirable reactions (e.g., tar formation). In addition, the low thermal conductivity leads to a significant increase in the surface area of ​​the exchanger, resulting in very high costs.

[0007] Therefore, there is a need to propose a treatment method with high yield and improved selectivity for recycling waste containing organic and inorganic substances.

[0008] The invention enables hydrothermal gasification, optimizing all its advantages: conversion of complex mixtures containing organic and non-organic solid substances into reusable gaseous, liquid and solid products. This is achieved thanks to the interconnection of several treatment and selective recovery steps, while minimizing cost constraints thanks to the perfect homogenization of the input biomass and, in particular, due to the drastic reduction of viscosity. Summary of the invention

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

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

[0011] b) pressurizing at least a portion of the hydrolyzed mixture M1h,

[0012] c) a heating step of heating the mixture M1h resulting from step b) to obtain a mixture M2,

[0013] d) a first separation step of separating at least a portion of the mixture M2 resulting from step c) in order to obtain a first stream M3 enriched in inorganic substances and a first stream M4 depleted in inorganic substances,

[0014] e) a heating step carried out on at least a portion of the first flow M4 depleted in inorganic matter,

[0015] f) a second separation step of separating at least part of the first stream M4 depleted in inorganic matter resulting from step e) to obtain a second stream M5 enriched in inorganic matter and a second stream M6 depleted in inorganic matter,

[0016] g) A hydrothermal gasification step of subjecting at least a portion of the second flow M6 lean in inorganic matter to a hydrothermal gasification to obtain at least a flow M8 comprising a gaseous and liquid effluent.

[0017] According to one embodiment of the process of the invention, the pressurizing step b) can raise the pressure of the hydrolyzed mixture M1h to a pressure of 150 to 300 bar and / or the heating step c) can heat the mixture M1h resulting from step b) to a temperature of 200° C. to 350° C.

[0018] According to one embodiment of the method of the invention, the heating step e) makes it possible to heat all or part of the first flow M4 lean in inorganic matter to a temperature ranging from 300°C to less than 600°C.

[0019] According to one embodiment of the process of the invention, the pressurization step b) brings the hydrolyzed mixture M1h to a pressure of 150 to 220 bar, the process further comprising pressurizing the first flow M4 of inorganic-poor matter resulting from step d), the pressurization being carried out upstream of the heating in step e).

[0020] Preferably, the first stream M4 lean in inorganic matter resulting from step d) is brought to a pressure greater than or equal to 225 bar to obtain a stream M4' and the heating step e) is capable of heating the stream M4' to a temperature ranging from 400°C to less than 600°C.

[0021] According to one embodiment of the method of the invention, the gasification step comprises a separation step making it possible to obtain a stream M8 and a stream M7 rich in inorganic substances.

[0022] According to one embodiment, the process of the invention further comprises at least one recovery step of recovering at least a portion of the inorganic substance in salt form, said recovery step being carried out on at least a portion of a stream selected from:

[0023] - first-rate M3 rich in inorganic substances, and

[0024] - a second stream M5 rich in inorganic substances,

[0025] - Stream M7 rich in inorganic substances.

[0026] According to one embodiment of the process according to the invention, the mixture M1 comprises 5 to 50 wt. % solid matter, preferably 15 to 25 wt. % solid matter, relative to the total weight of the mixture M1.

[0027] According to one embodiment of the process of the invention, the first stream M3 rich in inorganic matter resulting from step d) contains silicon dioxide in a proportion preferably ranging from 10% to 30% by weight relative to the total dry weight of the first stream M3 rich in inorganic matter.

[0028] According to one embodiment of the process of the invention, the second stream M5 rich in inorganic matter resulting from step f) contains phosphorus in a proportion preferably ranging from 1% to 20% by weight relative to the total dry weight of the stream M5 rich in inorganic matter.

[0029] According to one embodiment of the process according to the invention, at least one additive is added, preferably to at least a portion of a stream selected from:

[0030] - a flow of mixture M1 upstream of step a),

[0031] - a flow of mixture M1h upstream of step c),

[0032] - a flow of the mixture M2 resulting from step c),

[0033] -First-rate M3 rich in inorganic substances,

[0034] - a second stream M5 rich in inorganic substances,

[0035] - Stream M7 rich in inorganic substances.

[0036] Preferably, at least one first additive is added to the first stream M3 rich in inorganic matter resulting from step d) and at least one second additive is added to the second stream M5 rich in inorganic matter resulting from step f), the first additive preferably being different from the second additive.

[0037] According to one embodiment of the invention, the method further comprises a recovery step of the heat present in the stream M8 resulting from the hydrothermal gasification, the recovered heat preferably being used to at least partially heat the mixture M1h during the heating step c).

[0038] According to one embodiment of the invention, the method further comprises at least one digestion step carried out on at least a portion of the liquid effluent M10 obtained by cooling and then expanding at least a portion of the stream M8 resulting from step g).

[0039] The invention also relates to a device for implementing the treatment method according to the invention, comprising:

[0040] one or more hydrolysis reactors, optionally comprising stirring means and fed at the inlet by a line for supplying the mixture M1 to be treated and comprising an outlet line for the hydrolyzed mixture,

[0041] - optionally a mechanical grinding device fed by and comprising an outlet line for the hydrolyzed mixture,

[0042] a pressure pump which is fed at the inlet with the optionally ground hydrolyzed mixture,

[0043] - a heating device comprising an inlet capable of introducing at least a portion of the pressurized mixture downstream of the pump,

[0044] a first 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,

[0045] - optionally a pressurizing pump fed by at least part of the stream M4 lean in inorganic matter making it possible to obtain a stream M4',

[0046] a heating device fed by the flow M4 of inorganic-poor matter coming from the separation device or, when a booster pump is present, by the flow M4' of inorganic-poor matter coming from the booster pump,

[0047] a second separation device fed by at least a portion of the heated mixture coming from the heating device and comprising an outlet for a stream M5 rich in inorganic matter and an outlet for a stream M6 lean in inorganic matter,

[0048] A hydrothermal gasification reactor fed by at least part of the stream M6 lean in inorganic matter.

[0049] The invention enables improved treatment of organic matter in complex wet matrices, such as wet biomass and biowaste, in particular industrial, food or agri-food biowaste, and sewage sludge and sludge from purification plants.

[0050] Improvements in this treatment allow better recycling of inorganic substances, such as salts and metals, on the one hand, and of organic substances, on the other hand.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] [ Figure 1 ] is a schematic diagram of the processing method according to the present invention.

[0053] [ Figure 2 ] is a schematic diagram of the processing method according to the present invention.

[0054] [ Figure 3 ] is a schematic diagram of the processing method according to the present invention.

[0055] [ Figure 4 ] is a schematic diagram of the processing method according to the present invention. DETAILED DESCRIPTION

[0056] The present invention relates to a method for treating a mixture M1 comprising at least organic matter, said method comprising:

[0057] a. a hydrolysis step: hydrolyzing the mixture M1 at a temperature of 70°C to 165°C and a pressure of 2 to 8 bar to obtain a hydrolyzed mixture M1h,

[0058] b. pressurizing at least a portion of the hydrolysis mixture M1h, preferably the entire hydrolysis mixture M1h,

[0059] c. a heating step of heating the mixture M1h obtained from step b) to obtain a mixture M2,

[0060] d. a first separation step of separating at least a portion of the mixture M2 obtained from step c), preferably the entire mixture M2, to obtain a first stream M3 rich in inorganic substances and a first stream M4 poor in inorganic substances,

[0061] e. a heating step of heating at least a portion of the first flow M4 of the inorganic substance depletion, preferably the entire first flow M4 of the inorganic substance depletion,

[0062] f. a second separation step: separating at least a portion of the first stream M4 obtained from step e) of the inorganic substance-poor stream, preferably all of the first stream M4, to obtain a second stream M5 rich in inorganic substances and a second stream M6 poor in inorganic substances,

[0063] g. Hydrothermal gasification step: hydrothermally gasify at least a portion of the second flow M6 lean in inorganic matter, preferably the entire second flow M6 lean in inorganic matter, to obtain gaseous and liquid effluents.

[0064] 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.

[0065] 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.

[0066] Mixtures containing at least organic matter M1

[0067] 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.

[0068] The mixture M1 can be selected, for example, from primary sludge, mixed sludge or biological sludge from municipal and industrial purification plants.

[0069] 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.

[0070] Hydrolysis step a)

[0071] The process according to the invention comprises a step of hydrolyzing the mixture M1.

[0072] The hydrolysis step is carried out at a temperature ranging from 70 to 165° C. and a pressure ranging from 2 to 8 bar. These conditions make it possible to avoid evaporation of the medium.

[0073] According to one embodiment, the temperature during the hydrolysis step a) ranges from 100 to 165°C, or even from 140 to 165°C.

[0074] The hydrolysis step makes it possible to reduce the viscosity of the mixture. Thus, step a) makes it possible to obtain a mixture M1h, also called hydrolyzate.

[0075] 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.

[0076] 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.

[0077] 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).

[0078] 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.

[0079] The hydrolysis step is capable of hydrolyzing the mixture M1, in particular by maintaining an average hydraulic retention time at a desired temperature and pressure (in the process of the invention, a temperature ranging from 70°C to 165°C and a pressure ranging from 2 to 8 bars), 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.

[0080] 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.

[0081] 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.

[0082] 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 b) of the process of the invention.

[0083] The extraction of the hydrolysate M1h can be controlled by measuring the viscosity.

[0084] According to one embodiment, at least one additive is:

[0085] - added to the mixture M1 to be treated before entering the hydrolysis unit, and / or

[0086] - added to the mixture during hydrolysis, and / or

[0087] - Added to mixture M1h downstream of the hydrolysis.

[0088] According to one embodiment, the additive is selected from alkaline reagents such as KOH, NaOH, KHCO3, K2CO3, CaO, Ca(OH)2, CaCO3, Ca(HCO3)2, Mg(OH)2, MgO.

[0089] 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.

[0090] Steam can:

[0091] - upstream of the hydrolysis, into the inlet of a mixer of the dynamic mixer type, and / or

[0092] - direct injection into the hydrolysis reactor, preferably tangentially at the bottom to avoid clogging with sludge, and / or

[0093] - Injection into the recirculation loop of hydrolyzed sludge.

[0094] According to one embodiment, during the hydrolysis, the mixture M1 is mixed, for example stirred.

[0095] The hydrolysis reactor may be a batch reactor, optionally with stirring.

[0096] Prior to pressing b), the treatment process may optionally comprise a grinding step, preferably mechanical grinding.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] As with the hydrolysis step, grinding and particle size reduction also aid in homogenization of the biomass.

[0104] In reactors using high pressure, mechanical stirring is difficult to carry out, and the viscosity reduction achieved due to the hydrolysis step and / or the grinding step can also improve the internal turbulence and thus the homogenization in the pressurized reactor.

[0105] Pressurization step b)

[0106] The process according to the invention comprises a step of pressurizing the mixture M1h to a pressure ranging from 150 to 300 bar, preferably from 170 to 250 bar.

[0107] For the pressurization step, a pump may be provided on the line at the outlet of the hydrolysis reactor.

[0108] In another embodiment, a pump provided for this purpose pressurizes the booster pump.

[0109] Heating step c)

[0110] The process according to the invention comprises a step of heating the mixture M1h obtained from step b) to a temperature ranging from 200 to 400°C, preferably from 240 to 350°C.

[0111] The heating step may be carried out in a heat exchanger, for example by using the stream resulting from step g) of the process as a heating fluid for heat exchange. The stream resulting from step g) of the process typically comprises water and gas.

[0112] Thus, a heat exchanger may be present downstream of the booster pump, said heat exchanger being configured to recover the heat of the stream resulting from step g) and to heat the mixture M1h before the separation step d).

[0113] The heated mixture at the end of step c) is referred to as mixture M2.

[0114] According to one embodiment, at least one additive is added to the flow of the mixture M2, preferably after the heating device of step c) and before the first separation device of step d).

[0115] According to this embodiment, the additive is selected from an oxidizing agent or an alkaline agent. Among the oxidizing agents, for example, liquefied oxygen, hydrogen peroxide, air or permanganates such as potassium permanganate can be cited. Among the alkaline agents, for example, KOH, NaOH, KHCO3, K2CO3, CaO, Ca(OH)2, CaCO3, Ca(HCO3)2, Mg(OH)2, MgO can be cited.

[0116] First separation step d)

[0117] The method according to the invention comprises a first separation step: separation of the mixture M2 resulting from step c) so as to obtain a first stream M3 rich in inorganic substances and a first stream M4 poor in inorganic substances.

[0118] 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.

[0119] 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 .

[0120] 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.

[0121] This first separation step is generally carried out in a separation device comprising a supply line for the mixture M2 resulting from step c) and two outlet lines: (i) a line for extracting a first stream M3 rich in inorganic matter and (ii) a line for extracting a first stream M4 poor in inorganic matter.

[0122] The first separation device may be a hydraulic separation device of the cyclone type or a gravity separation device, usually equipped with a discharge system at the bottom, operating continuously or intermittently.

[0123] According to one embodiment, at least one additive is added to the stream M3 rich in inorganic substances resulting from step d).According to one embodiment, said additive is added to the stream M3 in a recovery reactor situated downstream of the first separation device.

[0124] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air, permanganates such as potassium permanganate, or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline reagents 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 reagents.

[0125] According to one embodiment, the additive is an ammonia solution from the liquid effluent M10 obtained after cooling and expansion of the stream M8 from the hydrothermal gasification (step g of the process of the invention).

[0126] When the formation of struvite is desired, the additive added to stream M3 is preferably a magnesium salt, optionally as a mixture with an ammonia solution.

[0127] According to one embodiment, if the stream M3 comprises at least 50% by dry weight of silica relative to the total dry weight of the first stream M3, preferably the process will comprise a step of adding an additive chosen from oxidizing agents.

[0128] When a reclaimer is used, the residence time can be set so that the target salt can be precipitated by adding the additive.

[0129] According to one embodiment, the mixture M1 comprises silicon dioxide. According to this embodiment, the first stream M3 rich in inorganic matter obtained from step d) comprises silicon dioxide in a proportion preferably ranging from 10% to 70% by dry weight relative to the total dry weight of the first stream M3 rich in inorganic matter.

[0130] Optional pressurization step

[0131] According to one embodiment, the treatment method according to the invention comprises a second pressurization step of applying pressure to the first flow M4 of inorganic matter depleted resulting from step d) upstream of step e). The flow resulting from this optional pressurization step is called flow M4'.

[0132] According to this embodiment, preferably, the first pressurization step enables the hydrolyzed mixture M1h to be brought to a pressure ranging from 150 to 220 bar and the second pressurization step enables the first stream M4 of inorganic-poor matter obtained from step d) to be brought to a pressure greater than or equal to 225 bar.

[0133] The hydrothermal gasification method of the prior art works at a single working pressure. According to an advantageous embodiment of the present invention, the method of the present invention uses two working pressures. This dual pressure operation provides many advantages.

[0134] On the one hand, only a portion of the device is placed under very high pressure (after the second pressurization, only the "second portion"), thus reducing construction costs as well as installation constraints.

[0135] On the other hand, at the moment of heat exchange, there is a substantial change of energy with a low temperature increment (ΔT) that is not simultaneous. This makes it possible to have a ΔT that is a greater heat exchange intensity in the exchanger and therefore a smaller exchanger.

[0136] The second pressurization enables the heating step e) to be carried out with lower energy consumption.

[0137] Heating step e)

[0138] The method according to the invention comprises a heating step carried out on the first flow M4 lean in inorganic matter, preferably at a temperature greater than or equal to 300°C and less than 600°C.

[0139] When the second pressurization step is carried out, the stream M4' depleted in inorganic matter obtained from the second pressurization step is then subjected to said heating step e).

[0140] When the method comprises a second pressurizing step, then preferably, the heating step e) is capable of heating the first flow M4' lean in inorganic matter to a temperature greater than or equal to 400°C and less than 600°C.

[0141] The heating step e) can be carried out in a heating device selected from electrical heating or indirect heating by hot gases generated by combustion.

[0142] Second separation step f)

[0143] The process according to the invention comprises a second separation step carried out on the first stream M4 depleted in inorganic matter obtained from the heating step e) so as to obtain a second stream M5 enriched in inorganic matter and a second stream M6 depleted in inorganic matter.

[0144] When the second pressurization step is carried out, the first stream M4' depleted in inorganic matter obtained from the heating step e) is then subjected to a second separation step f) to obtain a second stream M5 enriched in inorganic matter and a second stream M6 depleted in inorganic matter.

[0145] According to one embodiment, the ratio of the concentration of inorganic substances in the stream M5 rich in inorganic substances to the concentration of inorganic substances in the stream M4 is at least 2, preferably at least 5.

[0146] This second separation step is generally carried out in a separation device comprising a supply line of the mixture M4 (or M4', if a second pressurization is present) obtained from step e) and two outlet lines: (i) a line for extracting a second stream M5 rich in inorganic substances and (ii) a line for extracting a second stream M6 poor in inorganic substances.

[0147] The second separation device can 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, at least one additive is added to the second stream M5 rich in inorganic substances resulting from step f).According to one embodiment, said additive is added to the stream M5 in a recovery reactor situated downstream of the second separation device.

[0149] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air, permanganates such as potassium permanganate, or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline reagents 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 reagents.

[0150] When a first additive is added to the stream M3 and when a second additive is added to the stream M5, then preferably the first additive is different from the second additive.

[0151] According to one embodiment, the additive is an ammonia solution from the liquid effluent M10 obtained after cooling and expansion of the stream M8 coming from the hydrothermal gasification (step g of the process of the invention).

[0152] When struvite formation is desired, the additive added to stream M5 is preferably a magnesium salt, optionally as a mixture with an ammonia solution.

[0153] When a reclaimer is used, the residence time can be set so that the target salt can be precipitated by adding the additive.

[0154] According to one embodiment, the mixture M1 contains phosphorus and the second stream M5 rich in inorganic matter resulting from step f) 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 stream M5 rich in inorganic matter resulting from step f).

[0155] According to one embodiment, the mixture M1 comprises phosphorus and the second stream M5 rich in inorganic matter resulting from step f) comprises phosphorus in a proportion preferably ranging from 1% to 20% by weight relative to the total dry weight of the stream M5 rich in inorganic matter from step f).

[0156] According to one embodiment, the method according to the invention further comprises at least one recovery step of recovering at least a portion of the inorganic substances in the form of salts, said recovery step being carried out on at least one stream selected from:

[0157] - first-rate M3 rich in inorganic substances, and

[0158] - A second stream M5 rich in inorganic substances.

[0159] The recovery step may optionally include a step of adding at least one additive.

[0160] According to one embodiment of the method, at least one first additive is added to the organic matter stream M1h upstream of step d) and at least one second additive is added to the first inorganic matter-rich stream M3 resulting from step d), the first additive preferably being different from the second additive.

[0161] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air, permanganates such as potassium permanganate, or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline reagents 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 reagents.

[0162] According to one embodiment, the additive is an ammonia solution from the liquid effluent M10 obtained after cooling and expansion of the stream M8 coming from the hydrothermal gasification (step g of the process of the invention).

[0163] According to one embodiment of the method, at least one first additive is added to the organic substance flow M1h upstream of step d), at least one second additive is added to the first inorganic substance-rich flow M3 produced by step d), and at least one third additive is added to the second inorganic substance-rich flow M5 produced by step f), wherein the first additive is preferably different from the second additive and the third additive, and the second additive is preferably different from the third additive.

[0164] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air, permanganates such as potassium permanganate, or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline reagents 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 reagents.

[0165] According to one embodiment, the additive is an ammonia solution from the liquid effluent M10 obtained after cooling and expansion of the stream M8 coming from the hydrothermal gasification (step g of the process of the invention).

[0166] Hydrothermal gasification step g)

[0167] The treatment process according to the invention comprises a hydrothermal gasification step g).

[0168] 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.

[0169] In the GH process, carbon and hydrogen of organic substances are thermochemically converted under quasi-critical or supercritical conditions. Part of the conversion is into water-soluble low-molar-mass compounds.

[0170] 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).

[0171] 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.

[0172] 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.

[0173] Methane is also produced by methanation of CO and CO2 using hydrogen.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] Under HTL conditions, water still contains HO- and H3O+ ions that initiate the hydrolysis of organic matter.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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).

[0182] In the treatment method according to the invention, the hydrothermal gasification step is generally carried out in a hydrothermal gasification reactor supplied at the inlet with a second stream M6 lean in inorganic matter and comprising at least one outlet for a stream M8 comprising gaseous and liquid effluents and optionally at least one second outlet for a stream M7 rich in inorganic matter.

[0183] The inorganic substance-rich stream M7 comprises an inorganic substance content greater than that of stream M6. Preferably, the weight ratio between the inorganic substance content of stream M7 and that of stream M6 is greater than or equal to 2, preferably greater than or equal to 5.

[0184] The separation of the streams M7 and M8 can be carried out by a separation which can take place by gravity sedimentation of the stream M7.

[0185] According to one embodiment, the gasification reactor is a tubular reactor.

[0186] Preferably, the hydrothermal gasification step is carried out at a temperature below 600°C, preferably from 350°C to below 600°C, more preferably from 450°C to below 600°C.

[0187] 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.

[0188] Preferably, the (total) residence time of the stream M6 lean in inorganic substances in step g) of GH is generally between 1 minute and 20 minutes, preferably between 2 minutes and 10 minutes, more preferably between 3 and 5 minutes.

[0189] According to an optional embodiment, the hydrothermal gasification step is carried out in the presence of a catalyst. Preferably, the catalyst is chosen from metals on activated carbon, such as metals of the ruthenium, nickel, palladium or platinum type.

[0190] The catalyst may be in the form of a bed of solid particles within the gasification reactor.

[0191] Since separation steps d) and f) of the process according to the invention enable the removal of so-called "poison" compounds, the catalyst optionally used in the hydrothermal gasification step is not degraded by these harmful compounds which could damage the catalyst, in particular deactivate it.

[0192] In the context of the present invention, the hydrothermal gasification step makes it possible to obtain at least a stream M8 comprising a gas mixture dissolved in a liquid effluent.

[0193] According to one embodiment, the hydrothermal gasification step also makes it possible to obtain a stream M7 rich in inorganic substances. According to this embodiment, preferably, at least one additive is added to the stream M7.

[0194] Preferably, the additive is selected from oxidants such as liquefied oxygen, hydrogen peroxide, air, permanganates such as potassium permanganate, or from magnesium salts such as magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO) or magnesium chloride (MgCl2), or from alkaline reagents 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 reagents.

[0195] According to one embodiment, the method further comprises a step of recovering the inorganic substances, preferably the salts, carried out on at least part of the stream M7 resulting from the hydrothermal gasification step.

[0196] According to one embodiment, before the optional digestion step, the stream M8 resulting from step g) is cooled to a temperature less than or equal to 100° C., preferably less than or equal to 60° C. The cooling step is preferably carried out by heat exchange with a stream upstream of step g), preferably upstream of the first separation step.

[0197] According to one embodiment, the heat present in the stream M8 resulting from step g) is recovered, said recovered heat preferably being able to at least partially heat the mixture M1h during step c).

[0198] Preferably, this heat recovery is carried out by heat exchange between the gas coming from step g) and the mixture M1h.

[0199] Cooling can be performed using a cooling device selected from a heat exchanger, a flash evaporator, a scrubber, and a Rankine cycle.

[0200] According to one embodiment, the stream M8 is expanded in an expansion device to a pressure of 1 to 2 bar. This expansion step makes it possible to recover, on the one hand, the gases produced during step g) (stream M9) and, on the other hand, a liquid effluent (stream M10). According to this embodiment, at least a portion of the liquid effluent M10 produced by the expansion can be used to feed the digestion unit.

[0201] Optional digestion step

[0202] According to one embodiment, the treatment method according to the invention comprises at least one digestion step carried out on at least a portion of the liquid effluent M10 obtained by cooling and expanding the stream M8 resulting from the hydrothermal gasification step g).

[0203] According to one embodiment, the treatment method according to the invention comprises at least one anaerobic digestion step carried out on the pre-expanded liquid effluent resulting from the hydrothermal gasification step g).

[0204] Anaerobic digestion can be either mesophilic or thermophilic.

[0205] 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.

[0206] 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.

[0207] Residence time and temperature are two factors that influence the optimization of good degradation of sludge and thus energy production.

[0208] At the end of the digestion step, biogas is obtained.

[0209] Such biogas usually comprises a mixture consisting essentially of methane, carbon dioxide and water. The biogas may optionally contain other gases, such as hydrogen, oxygen, nitrogen or hydrogen sulfide, but these other gases together account for less than 10% by weight of the total weight of the biogas.

[0210] According to one embodiment, the processing method according to the present invention comprises:

[0211] 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 to 8 bar to obtain a hydrolyzed mixture M1h,

[0212] b. pressurizing at least a portion of the hydrolyzed mixture M1h, preferably the entire hydrolyzed mixture M1h, so that the hydrolyzed mixture M1h reaches a pressure of 150 to 250 bar,

[0213] c. a heating step of heating the mixture M1h obtained from step b) to obtain a mixture M2 having a temperature ranging from 200 to 350 degrees,

[0214] d. a first separation step of separating the mixture M2 obtained from step c) to obtain a first stream M3 enriched in inorganic substances and a first stream M4 depleted in inorganic substances,

[0215] a second pressurization step of pressurizing the first stream M4 of inorganically depleted material obtained from step d) to obtain a stream M4′,

[0216] e. a heating step of heating at least a portion of the stream M4′, preferably the entire stream M4′, to a temperature of at least 300° C. and less than 600° C.,

[0217] f. a second separation step of separating at least a portion of the stream M4′ obtained in step e) to obtain a second stream M5 enriched in inorganic substances and a second stream M6 depleted in inorganic substances,

[0218] g. hydrothermal gasification of at least a portion of the second flow M6 lean in inorganic matter, preferably of the entire second flow M6 lean in inorganic matter, to obtain at least a hydrothermal gasification step of a flow M8 comprising gaseous and liquid effluents, said gasification step preferably being carried out at a temperature below 600° C.,

[0219] Therein, the hydrothermal gasification step optionally makes it possible to obtain, in addition to the stream M8, a stream M7 rich in inorganic substances, said stream M7 being obtainable by a separation which produces, on the one hand, the stream M7 and, on the other hand, the stream M8.

[0220] According to one embodiment, the processing method according to the present invention comprises:

[0221] 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 to 8 bar to obtain a hydrolyzed mixture M1h,

[0222] b. pressurizing at least a portion of the hydrolyzed mixture M1h, preferably the entire hydrolyzed mixture M1h, so that the hydrolyzed mixture M1h reaches a pressure of 150 to 250 bar,

[0223] c. a heating step of heating the mixture M1h obtained from step b) to obtain a mixture M2 having a temperature ranging from 200 to 350 degrees,

[0224] d. a first separation step of separating the mixture M2 obtained from step c) to obtain a first stream M3 enriched in inorganic substances and a first stream M4 depleted in inorganic substances,

[0225] a second pressurization step of pressurizing the first stream M4 of inorganically depleted material obtained from step d) to obtain a stream M4′,

[0226] e. a heating step of heating at least a portion of the stream M4′, preferably the entire stream M4′, to a temperature of at least 300° C. and less than 600° C.,

[0227] f. a second separation step of separating at least a portion of the stream M4′ obtained in step e) to obtain a second stream M5 enriched in inorganic substances and a second stream M6 depleted in inorganic substances,

[0228] g. subjecting at least a portion of the second stream M6 lean in inorganic matter, preferably the entirety of the second stream M6 lean in inorganic matter, to a hydrothermal gasification step to obtain at least a stream M8 comprising gaseous and liquid effluents, and optionally a stream M7 rich in inorganic matter, said gasification step preferably being carried out at a temperature below 600° C.,

[0229] The method further comprises:

[0230] - a step of adding a first additive to the stream M3, and

[0231] - a step of adding a second additive to the stream M5, and

[0232] - optionally, a step of adding a third additive to stream M7,

[0233] Preferably, the three additives are different.

[0234] The invention also relates to a device for carrying out the treatment method according to the invention.

[0235] The device according to the invention comprises:

[0236] at least one hydrolysis reactor 1 , optionally comprising stirring means, fed at the inlet by a supply line for the mixture M1 to be treated and comprising an outlet line for the hydrolyzed mixture,

[0237] - optionally a mechanical grinding device fed by and comprising an outlet line for the hydrolyzed mixture,

[0238] - a pressure pump 3 fed by the optionally ground hydrolyzed mixture,

[0239] a heating device 4 comprising an inlet capable of introducing at least a portion of the pressurized mixture downstream of the pump 3,

[0240] a first separation device 51 , 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 lean in inorganic matter,

[0241] - optionally a pressurizing pump 61 fed by at least part of the stream M4 lean in inorganic matter making it possible to obtain a stream M4',

[0242] a heating device 6 fed by the flow M4 depleted in inorganic matter coming from the separation device 51 or by the flow M4 ′ depleted in inorganic matter coming from the booster pump 61 (when the booster pump 61 is present),

[0243] a second separation device 71 , fed by at least part of the heated mixture coming from the heating device 6 and comprising an outlet for a stream M5 rich in inorganic matter and an outlet for a stream M6 lean in inorganic matter,

[0244] A hydrothermal gasification reactor 8 fed by at least part of the stream M6 lean in inorganic matter.

[0245] Thus, 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 mixture M1h hydrolyzed at a temperature lower than or equal to the hydrolysis temperature. The hydrolysis reactors 1 advantageously comprise heating and pressurizing means and optionally stirring means, and advantageously internal heat recovery means.

[0246] Optionally, the device may further include one or more elements selected from the following:

[0247] a heat exchanger 9 for recovering the heat present in the stream M8 coming from the hydrothermal gasification reactor 8,

[0248] and / or

[0249] an expansion device 10 fed by the stream M8 resulting from the hydrothermal gasification and comprising an outlet for the liquid effluent, and / or

[0250] A digestion unit 11 , which is fed by at least part of the liquid effluent resulting from the expansion 10 .

[0251] Preferably, if the apparatus comprises a heat exchanger 9 and an expansion device 10 , the expansion device 10 is located downstream of the heat exchanger 9 .

[0252] According to one embodiment of the plant, the heating device 4 is a heat exchanger configured to recover heat from the flow M8 downstream of the gasification reactor.

[0253] The device according to the invention may optionally comprise both heating means 4 of the heat exchanger type configured to recover heat from the flow M8 downstream of the gasification reactor and a (further) heat exchanger 9 capable of further cooling the flow M8.

[0254] The plant may optionally comprise means for recovering inorganic substances, in particular for recovering salts.According to this embodiment, the plant according to the invention preferably comprises at least one additive injection device.

[0255] Preferably, the apparatus comprises at least one additive injection device for injecting an additive into at least one of the following streams:

[0256] - a flow of the mixture M1 upstream of the hydrolysis unit 1,

[0257] - a flow of the mixture M1h downstream of the hydrolysis device and upstream of the heating device 4,

[0258] - the flow of the mixture M2 downstream of the heating device 4 (upstream of the separation device 51),

[0259] a first stream M3 rich in inorganic substances downstream of the separation device 51,

[0260] a second stream M5 rich in inorganic substances downstream of the second separation device 71,

[0261] - an optional stream M7 rich in inorganic substances coming from the hydrothermal gasification reactor.

[0262] The method and the device according to the invention are capable of treating a mixture comprising organic and inorganic substances in order to reuse the substances with optimum yield and selectivity.

[0263] The nature of the additive is specifically chosen according to the salts that one wishes to recycle, which salts themselves may be determined according to the quality and type of mixture M1 entering the process.

[0264] Figure 1 , Figure 2 , Figure 3 and Figure 4 Each illustrates a device according to the invention without limiting its scope.

[0265] The figures show different injection points for at least one additive, it being understood that the device according to the invention may comprise one or more injection points. Preferably, there are a plurality of injection points, in particular at least one injection point upstream of the first separation device 51 and at least one injection point for injection into the line of stream M3, as well as at least one injection point for injection into the line of stream M5 and at least one injection point for injection into the line of stream M7.

[0266] like Figure 1 As shown, in the context of the present invention, a mixture M1 comprising organic and inorganic matter (for example biomass or sludge type from a purification station), optionally with the addition of additives, is introduced into a hydrolysis reactor 1 comprising an inlet for introducing the mixture M1 and an outlet for the hydrolyzed mixture M1h.

[0267] The hydrolysis reactor 1 can optionally be preceded by a grinding device or can be equipped with a recirculation loop provided with a grinding device or can be followed by a grinding device before the pressure pump 3 .

[0268] In the context of the present invention, the hydrolyzed mixture M1h pressurized by the pressure pump 3 is then introduced into the heating device 4. The heating device 4 is generally capable of bringing the mixture to a temperature of 200 to 400°C, preferably 240 to 350°C (the mixture is then referred to as M2).

[0269] In the context of the present invention, the mixture M2 is then introduced into a separation device 51 to obtain a first stream M3 rich in inorganic matter and a first stream M4 lean in inorganic matter. Upstream of the separation device 51, additives may optionally be added to the stream of the mixture M2 to facilitate the separation.

[0270] exist Figure 1 In the context of the invention shown, the first flow M4 lean in inorganic matter is then introduced into a heating device 6 capable of heating the flow M4 preferably to a temperature greater than or equal to 300°C and less than 600°C.

[0271] exist Figure 1 In the context of the invention shown, the heated mixture leaving the heating device 6 is then introduced into a second separation device 71 making it possible to obtain a second stream M5 rich in inorganic substances and a second stream M6 poor in inorganic substances.

[0272] exist Figure 1 In the context of the invention shown, the second flow M6 of inorganic-poor matter is then introduced into the hydrothermal gasification reactor 8 .

[0273] exist Figure 1 In the context of the invention shown, additives may optionally be added to the first inorganic substance-rich stream M3 and / or to the second inorganic substance-rich stream M5 and / or to the inorganic substance-rich stream M7 leaving the hydrothermal gasification.

[0274] Figure 2 An embodiment of the device and method according to the present invention is shown, which is Figure 1 The embodiment of is different in the second pressurizing step.

[0275] exist Figure 2 In the context of the invention shown, the first flow M4 depleted in inorganic matter leaving the first separation device 51 is subsequently pressurized by means of a pressurizing pump 61 , which makes it possible to obtain a flow M4 ′ which is subsequently introduced into the heating device 6 .

[0276] according to Figure 2 In the embodiment shown in , preferably, the pressure pump 3 is capable of bringing the hydrolyzed mixture M1h to a pressure of 150 to 220 bar, and the pressure device 61 is capable of bringing the flow M4 to a pressure greater than or equal to 225 bar.

[0277] Figure 3 An embodiment of the device and method according to the present invention is shown, which is Figure 2 The embodiment of is distinguished by the presence of recovery reactors 56, 74 and 84.

[0278] according to Figure 3 In one embodiment shown, the apparatus comprises a recovery device 56 downstream of the first separation device 51, the recovery device 56 being fed by the stream M3 optionally mixed with the additive. It should be noted that in the context of the present invention, the addition of the additive can optionally be carried out directly in the recovery device 56 (rather than as Figure 3 shown in stream M3).

[0279] according to Figure 3 In one embodiment shown, the apparatus comprises a recovery device 74 downstream of the second separation device 71, which is fed by the stream M5 optionally mixed with the additive. It should be noted that in the context of the present invention, the addition of the additive can optionally be carried out directly in the recovery device 74 (rather than as Figure 3 shown in stream M5).

[0280] according to Figure 3 In one embodiment shown, the apparatus comprises a recovery device 84 downstream of the hydrothermal gasification reactor, which is fed by a stream M7 optionally mixed with an additive. It should be noted that in the context of the present invention, the addition of the additive can optionally be carried out directly in the recovery device 84 (rather than as Figure 3 shown in stream M7).

[0281] Figure 4 An embodiment of the device and method according to the present invention is shown. Figure 3 The embodiment of differs in the presence of a heat recovery circuit capable of recovering the heat present in the stream M8 consisting of a mixture of gases dissolved in the liquid effluent from the hydrothermal gasification reactor 8 .

[0282] according to Figure 4 In one embodiment shown, the stream M8 coming from the hydrothermal gasification reactor 8 is cooled by heat exchange with the heating device 4 and supplied to the cooling device 9 (preferably by heat recovery).

[0283] according to Figure 4 In the embodiment shown, the flow leaving the heat recovery device 9 is then expanded in an expansion device 10 in order to obtain a gas flow M9 and a liquid flow M10 .

[0284] According to one embodiment, the liquid stream M10 feeds the digester 11 .

[0285] 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 hydrolysis step of hydrolyzing the mixture M1 at a temperature of 70 to 165° C. and a pressure of 2 to 8 bar to obtain a hydrolyzed mixture M1h, b. pressurizing at least a portion of the hydrolyzed mixture M1h, c. a heating step of heating the mixture M1h produced by step b) to obtain a mixture M2, d. a first separation step of separating at least a portion of the mixture M2 produced by step c) to obtain a first stream M3 rich in inorganic matter and a first stream M4 poor in inorganic matter, e. a heating step of at least a portion of the first flow M4 depleted in inorganic matter, f. a second separation step of separating at least a portion of the first stream M4 produced by step e) to obtain a second stream M5 rich in inorganic substances and a second stream M6 poor in inorganic substances, g. A hydrothermal gasification step of subjecting at least part of the second stream M6 lean in inorganic matter to a hydrothermal gasification to obtain at least a stream M8 comprising a gaseous and liquid effluent.

2. The processing method according to claim 1, wherein: The pressurizing step b) makes it possible to raise the pressure of the hydrolyzed mixture M1h to a pressure comprised between 150 and 300 bar and / or the heating step c) makes it possible to heat the mixture M1h resulting from step b) to a temperature comprised between 200°C and 350°C.

3. The processing method according to any one of claims 1 to 2, wherein: The heating step e) makes it possible to heat all or part of the first flow M4 lean in inorganic matter to a temperature ranging from 300°C to less than 600°C.

4. The processing method according to any one of claims 1 to 3, wherein: The pressurization step b) brings the hydrolyzed mixture M1h to a pressure of 150 to 220 bar, the method also comprising pressurizing the first stream M4 of inorganic-poor matter resulting from step d), this pressurization being carried out upstream of the heating of step e).

5. The processing method according to claim 4, wherein: The first stream M4 lean in inorganic matter resulting from step d) is brought to a pressure greater than or equal to 225 bar to obtain a stream M4' and the heating step e) is capable of heating the stream M4' to a temperature ranging from 400°C to less than 600°C.

6. The processing method according to any one of claims 1 to 5, wherein: The gasification step comprises a separation step making it possible to obtain a stream M8 and a stream M7 rich in inorganic substances.

7. The treatment process according to any one of claims 1 to 6, further comprising at least one recovery step of recovering at least a portion of the inorganic substances in salt form, said recovery step being carried out on at least a portion of a stream selected from: - first-rate M3 rich in inorganic substances, and - a second stream M5 rich in inorganic substances, - Stream M7 rich in inorganic substances.

8. The processing method according to any one of claims 1 to 7, 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.

9. The processing method according to any one of claims 1 to 8, wherein: The first stream M3 rich in inorganic matter resulting from step d) comprises silicon dioxide in a proportion preferably ranging from 10% to 30% by weight relative to the total dry weight of the first stream M3 rich in inorganic matter.

10. The processing method according to any one of claims 1 to 9, wherein: The second stream M5 rich in inorganic matter resulting from step f) comprises phosphorus in a proportion preferably ranging from 1% to 20% by weight relative to the total dry weight of the stream M5 rich in inorganic matter.

11. The processing method according to any one of claims 1 to 10, wherein: adding at least one additive, preferably to at least a portion of a stream selected from: - a flow of mixture M1 upstream of step a), - a flow of mixture M1h upstream of step c), - a flow of the mixture M2 resulting from step c), -First-rate M3 rich in inorganic substances, - a second stream M5 rich in inorganic substances, - Stream M7 rich in inorganic substances.

12. The processing method according to claim 11, wherein: At least one first additive is added to the first stream M3 rich in inorganic matter resulting from step d) and at least one second additive is added to the second stream M5 rich in inorganic matter resulting from step f), the first additive preferably being different from the second additive.

13. The treatment process according to any one of claims 1 to 12, further comprising a recovery step of the heat present in the stream M8 resulting from the hydrothermal gasification, the recovered heat preferably being used to at least partially heat the mixture M1h during the heating step c).

14. Process according to any one of claims 1 to 13, further comprising at least one digestion step carried out on at least a portion of the liquid effluent M10 obtained by cooling and then expanding at least a portion of the stream M8 resulting from step g).

15. A device for implementing the treatment method according to any one of claims 1 to 14, the device comprising: one or more hydrolysis reactors (1) which optionally comprise stirring means and which are fed at the inlet by a line for supplying the mixture M1 to be treated and comprise an outlet line for the hydrolyzed mixture, - optionally a mechanical grinding device fed by and comprising an outlet line for the hydrolyzed mixture, a pressure pump (3) which is fed at the inlet with the optionally ground hydrolyzed mixture, - a heating device (4) comprising an inlet capable of introducing at least a portion of the pressurized mixture downstream of the pump (3), a first separation device (51) 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, - optionally a pressurizing pump (61) fed by at least part of the stream M4 lean in inorganic matter, making it possible to obtain a stream M4', a heating device ( 6 ) fed by the flow M4 depleted in inorganic matter coming from the separation device ( 51 ) or, when a booster pump ( 61 ) is present, by the flow M4 ′ depleted in inorganic matter coming from the booster pump ( 61 ), a second separation device ( 71 ) fed by at least part of the heated mixture coming from the heating device ( 6 ) and comprising an outlet for a stream M5 rich in inorganic matter and an outlet for a stream M6 lean in inorganic matter, A hydrothermal gasification reactor (8) fed by at least part of the stream M6 lean in inorganic matter.

Images