Flexible device and method for upgrading biomass and waste by hydrothermal roasting and carbonization

Abstract

The invention relates to a system and a method for the flexible thermoconversion of biomass by torrefaction or hydrothermal carbonization of all types of biomass, depending on the biomass moisture content. The present invention relates to the technical field of thermoconversion of biomass and waste to produce energy and / or materials. The invention will find particular application in the valorization of sewage sludge, manure, and driftwood waste, the moisture content of which can vary considerably.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of thermoconversion of biomass and waste to produce energy and / or materials. The invention will find particular application in the recovery of sewage sludge, manure, and driftwood waste, the moisture content of which can vary considerably. STATE OF THE ART

[0002] Among the "mild" thermochemical conversion methods used in biomass pretreatment or as a direct conversion method, torrefaction and hydrothermal carbonization (HTC) are used to treat dry and wet inputs, respectively. Outside the recommended moisture content range for the input in question, either of these processes can be applied interchangeably, but at a significant energy cost.

[0003] The market is segmented between the treatment route for dry biomass by torrefaction and the treatment route for wet biomass by HTC.

[0004] Roasting and hydrothermal carbonization (HTC) are two ways of converting raw biomass into a "biochar" (sometimes called "biocoal" or "biochar" for roasting and "hydrochar" for hydrothermal carbonization) some of whose properties are close to those of mineral coal.

[0005] Dry torrefaction (or roasting) is a slow and gentle pyrolysis or carbonization process carried out under an inert gas at atmospheric pressure, at temperatures ranging from 200 to 300°C and residence times on the order of an hour. The degradation of the main macromolecular components of the biomass (primarily hemicellulose and cellulose) results in a loss of solid mass in the form of dry gases (H2, CO2, CO, CH4, etc.) and condensable gases (water vapor, phenols, acids). The residual solid exhibits an increased carbon content compared to the raw biomass, decreased hydrogen / carbon and oxygen / carbon ratios, increased grindability and hydrophobicity, improved sorption properties, etc., which enhances its potential for energy and material applications. These performance characteristics can only be achieved with dry biomass (moisture content < 20 to 25% by weight).Furthermore, the water vapor generated by the process degrades the roasting performance, so it is essential to pre-dry the wetter biomass before roasting.

[0006] The hot carbonization (HTC) process has attracted increasing interest in recent years. It involves the underwater carbonization of biomass under subcritical conditions, at temperatures ranging from 180 to 260°C, residence times from a few minutes to several hours, and pressures from 15 to 50 bar (1500 to 5000 kPa). Pressure is the variable used to maintain the water in liquid form at the target temperatures. The specific properties of water under these conditions promote the chemical reactions that degrade the components of the biomass. The main product of the reaction is a solid (hydrochar) with properties essentially equivalent to those of torrefaction biochar, and therefore significantly improved compared to those of the initial biomass for the aforementioned applications.

[0007] The economic advantages of the two processes can be segmented as follows: roasting for inputs with 20-25% moisture content and below, and high humidity (HT) for inputs with 65-70% moisture content and above. For intermediate moisture levels, a choice must be made between the two processes based on various factors related to the cost of the resource, the economic context, regulations, etc.

[0008] At the same time, a growing number of industrial companies and local authorities are seeking to valorize biomass residues or waste from various sources, with highly variable and difficult-to-control moisture levels. These constraints are creating an increased need for flexible thermochemical conversion processes that can adapt to all types of inputs, regardless of their moisture content. SUMMARY

[0009] To achieve this objective, according to one embodiment, a flexible biomass thermoconversion system by torrefaction or hydrothermal carbonization is envisaged, comprising a tank intended to be closed and to receive biomass and a gas ceiling, a nitrogen distribution module in the tank, a heating module intended to heat the biomass contained in the tank, a pressure control module at least in the tank.

[0010] According to one aspect, the nitrogen distribution module includes a distribution plate comprising a distribution chamber equipped with nitrogen distribution openings.

[0011] Advantageously, the system includes a control unit configured to adapt the operation of the system according to the percentage of moisture of the biomass to be treated, taking alternatively a first mode of thermoconversion by torrefaction when the percentage of moisture of the biomass to be treated is less than a first predefined threshold or a second mode of thermoconversion by hydrothermal carbonization when the percentage of moisture of the biomass to be treated is greater than a second predefined threshold.

[0012] This system is therefore suitable for processing biomass by thermoconversion regardless of its moisture content. The system allows for either thermoconversion by torrefaction or thermoconversion by hydrothermal carbonization using a single device.

[0013] According to another aspect, the invention relates to a biomass thermoconversion process adapted to the moisture of the biomass to be treated, characterized in that it comprises a preliminary step of determining the percentage of moisture of the biomass to be treated and an operating phase of a thermoconversion system as described above following a first thermoconversion mode by torrefaction or a second thermoconversion mode by hydrothermal carbonization depending on the percentage of moisture of the biomass to be treated previously determined. BRIEF DESCRIPTION OF THE FIGURES

[0014] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which: There figure 1represents a diagram of a thermoconversion system according to an embodiment of the invention for batch processing. figure 2 represents a detail A of a reactor of the thermoconversion system according to the figure 1 which can be used for batch processing. The figure 3 represents a detail A of the figure 1 according to another embodiment of the invention which can be used for continuous processing.

[0015] The drawings are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION

[0016] Before beginning a detailed review of embodiments of the invention, optional features which may be used in combination or alternatively are stated below: According to an example, the first predefined threshold of percentage of moisture of the biomass to be treated is 25% and the second predefined threshold of percentage of moisture of the biomass to be treated is 65%.

[0017] According to one example, the system includes an injection hopper (22) intended to supply the tank (1) with biomass, the hopper (22) and the tank (1) being at equal pressure.

[0018] According to one example, the hopper (22) includes a chamber pressurized at the pressure of the tank (1).

[0019] According to one example, the system includes a mixer (4) to ensure the movement of biomass configured to mix liquid phases and dry granular media, preferably the mixer (4) is chosen from a paddle mixer and a rotary mixer.

[0020] According to one example, the system includes a gas extraction module out of the tank (1) arranged in the upper part of the tank (1) comprising a gas extraction line (7), and preferably a heater for said gas extraction line.

[0021] According to one example, the system includes a thermal energy recovery module (8) for extracted gases comprising a thermal energy recuperator (24) intended to recover the thermal energy from the extracted gases for the benefit of preheating the nitrogen intended to be distributed in the tank (1).

[0022] According to one example, the thermal energy recovery module for extracted gases includes a condenser (9) intended to ensure the condensation of extracted gases arranged upstream of the recuperator (24).

[0023] According to one example, the system includes an extraction opening (23) for the thermoconverted biomass arranged in the lower part of the tank (1), preferably the extraction opening (23) is at equal pressure with the tank (1).

[0024] According to one example, the control unit is configured to control at least one of the following: the pressure control module, the nitrogen distribution module, the gas extraction module, the hopper, the extraction opening, the heating module.

[0025] According to one example, the first thermoconversion mode by torrefaction is activated for a percentage of biomass moisture below a first threshold, advantageously 25%.

[0026] According to one example, the second mode of thermoconversion by hydrothermal carbonization is activated for a percentage of biomass moisture above a second threshold, advantageously 65%.

[0027] According to one example, the process includes a phase of upgrading the percentage of biomass moisture prior to the operating phase if the percentage of biomass moisture determined by the preliminary determination step is between the first threshold, 25%, and the second threshold, 65%.

[0028] According to one example, the phase of upgrading the percentage of biomass moisture includes either increasing the percentage of moisture by adding water to the biomass to reach a percentage of biomass moisture above 65% or decreasing the percentage of moisture by drying the biomass to reach a percentage of biomass moisture of 25%.

[0029] As an example, the first mode of thermoconversion by roasting includes: the filling of the tank (1) with biomass having a percentage of biomass moisture below a first threshold, for example 25%, the mixing of the biomass by a mixer (4), injection of nitrogen by the nitrogen injection module into the tank (1) and pressurization of the tank (1) for example to a pressure of 1.2 bar (120 kPa), heating to a temperature for example between 200°C and 300°C of the biomass by the heating module (5), extraction of gases from the upper part of the tank (1) by the gas extraction module, condensation of the gases extracted from the tank (1) by the condenser (9) of the gas extraction module, extraction of the thermoconverted biomass into biochar.

[0030] According to one example, the process includes the recovery of thermal energy from the extracted gases for the preheating of the nitrogen injected into the tank by the recuperator (24).

[0031] According to one example, the second mode of thermoconversion by hydrothermal carbonization includes filling the tank (1) with biomass having a percentage of biomass moisture above a second threshold for example 65%, nitrogen purging of the tank (1), injection of nitrogen by the nitrogen injection module into the tank (1) and pressurization of the tank (1) to a pressure for example of 15 to 50 bar (1500 to 5000 KPa), mixing of the biomass by a mixer (4), heating to a temperature for example between 180°C and 260°C of the biomass by the heating module (5), extraction of the thermo-converted biomass into hydrobiochar.

[0032] According to one example, biomass filling and biomass extraction are continuous.

[0033] For the remainder of this description, 'top' and 'bottom', or their derivatives, refer to the relative positioning of a reactor or system component when it is functionally installed, with 'top' oriented away from the ground and 'bottom' oriented towards the ground. The upper end is at the top and the lower end is at the bottom.

[0034] Vertical refers to anything parallel to the direction of gravity, as indicated by a plumb line, and horizontal refers to anything perpendicular to the vertical. Up and down are vertically opposite.

[0035] Horizontal refers to anything perpendicular to the vertical.

[0036] Transverse is understood to mean a direction perpendicular to a longitudinal direction.

[0037] Upstream and downstream, inlet and outlet, at a given point are taken in reference to the direction of fluid flow.

[0038] A parameter "approximately equal to / greater than / less than" or "of the order of" a given value means that this parameter is equal to / greater than / less than the given value, to within 10% or even 5% of that value.

[0039] For the purposes of this disclosure, "A and / or B" means (A), (B), or (A and B). For the purposes of this disclosure, "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0040] Fluidically connected or in fluidic connection means when a line provides a connection through or in which a fluid flows.

[0041] In this description, the expression "A fluidly connected to B" is synonymous with "A is in fluidic connection with B" and does not necessarily mean that there is no organ between A and B. The expressions "arranged on" or "on" are synonymous with "fluidly connected to".

[0042] Hot, cold, cooled refers to a relative temperature compared to another point in the system.

[0043] The terms "first", "second" and "third", "additional" etc. are used simply as labels, and are not intended to impose numerical requirements on their objects.

[0044] The invention relates to a biomass thermal conversion system. The system comprises a thermal conversion reactor including a tank 1 for receiving the biomass to be treated. The tank includes at least one opening and may include a lid for closing the opening.

[0045] According to the invention, the biomass that can be processed by the system according to the invention has a moisture content between 0 and 100%. In the following description, biomass referred to as dry biomass is biomass with a moisture content of 25% or less, and biomass referred to as wet biomass is biomass with a moisture content of 65% or more. Biomass with a moisture content greater than 25% and less than 65% is defined as intermediate biomass.

[0046] Biomass refers to all organic matter that can be transformed into energy. In the context of the invention, biomass more specifically includes organic waste, sewage sludge, plant waste, decontaminated B wood (low-adjuvanted wood), and agricultural residues.

[0047] Tank 1 according to the invention is intended to be closed. Tank 1 is configured to withstand the operating pressures of the system ranging from approximately 1 bar (atmospheric pressure - 100 kPa) to approximately 100 bar (10,000 kPa).

[0048] Advantageously, tank 1 is intended to receive a volume of biomass less than the volume of tank 1, tank 1 thus comprising a gas ceiling above the biomass.

[0049] The system typically includes a heating module 5 designed to heat the biomass and maintain it at a target temperature. The heating module 5 can vary considerably, such as an induction heater located outside the tank 1 (the tank 1 being thermally conductive), or at least one electric heating element located outside the tank 1 in thermal conduction with the tank 1, or directly inside the tank 1 in contact with the biomass. The heating module 5 thus allows the heating to be adapted according to the moisture content of the biomass being treated, and therefore the thermo-conversion process implemented by the system. The heating module 5 is configured to heat the biomass to a target temperature between 180°C and 300°C.

[0050] The system includes a pressure control module 3, which operates within the system and preferentially within tank 1. This pressure control module adjusts the pressure according to the temperature of the biomass-water mixture to maintain the water in a liquid phase during hydrothermal carbonization operation. During torrefaction operation, the pressure control module 3 ensures the flow of the biomass-nitrogen mixture and its extraction from tank 1. The pressure control module 3 includes, for example, a pressure regulator 10 and a pressure gauge 11. The pressure control module 3 is configured to apply a pressure within the system, and more specifically within tank 1, ranging from atmospheric pressure (1.01325 bar - 101.325 kPa) to 100 bar (10,000 kPa).

[0051] According to one aspect of the invention, the system comprises a nitrogen distribution module in the tank 1. In the following description, the term nitrogen is used, but an equivalent inert gas could also be used. The nitrogen distribution module advantageously comprises at least one nitrogen supply line 6 in the tank 1. Advantageously, the nitrogen distribution module comprises a distribution plate 14 arranged in the tank 1. The distribution plate 14 is supplied by the nitrogen supply line. The distribution plate includes a distribution chamber for diffusing nitrogen into the distribution plate 14 and distribution openings 15 for injecting nitrogen into the tank 1 from the distribution chamber of the distribution plate 14.In a preferred embodiment, the distribution plate 14 is arranged in the tank 1 at the level of the gas head, and the distribution openings 15 are preferentially oriented towards the bottom of the tank 1, i.e., towards the biomass when it is present in the tank 1. For example, the distribution plate 14 has an upper face opposite to a lower face. The distribution openings 15 are preferentially located on the lower face of the distribution plate 14. The nitrogen distribution module allows the nitrogen to be distributed homogeneously over the surface of the biomass contained in the tank 1.

[0052] Advantageously, the pressure control module 3 is arranged on the nitrogen supply line 6.

[0053] According to one embodiment, the system, more specifically the nitrogen distribution module, includes a bypass circuit comprising a nitrogen preheating bypass line 17 arranged on, i.e. tapped on, the nitrogen supply line 6, preferably downstream of the pressure control module 3 and a preheated nitrogen return line 18 arranged on, i.e. tapped on, the nitrogen supply line 6 preferably downstream of the bypass line 17. The nitrogen flowing in the nitrogen supply line 6 can then be diverted towards the nitrogen preheating bypass line 17 to be preheated, preferably by a recuperator 24 as described below, and then returns towards the nitrogen supply line 6 by the preheated nitrogen return line 18.

[0054] Advantageously, the system includes a plurality of nitrogen circulation control valves in the different lines of the system and for example a control valve at the inlet of the bypass line 17, a control valve at the outlet of the return line 18 and a control valve on the nitrogen supply line 6.

[0055] According to one embodiment, the system includes a gas extraction module outside of tank 1. The gas extraction module advantageously includes a gas evacuation line 7 arranged in the upper part of tank 1.

[0056] According to one embodiment, the system includes a thermal energy recovery module 8 for the gases extracted from tank 1. The thermal energy recovery module 8 advantageously includes a recuperator 24 corresponding to a heat exchanger arranged at the interface of the gas extraction module, and in particular the gas exhaust line 7, and the nitrogen distribution module, and more particularly the nitrogen bypass line 17. The nitrogen circulating in the nitrogen distribution module, and more specifically in the bypass circuit, is advantageously preheated by the thermal energy recovery module before being injected into tank 1.

[0057] According to the embodiment, the thermal energy recovery module 8 for the gases extracted from tank one includes a condenser 9. The condenser 9 is advantageously arranged upstream of the heat recovery unit 24 on the gas exhaust line 7. The condenser 9 allows, on the one hand, the separation of dry and condensable gases to prevent any risk of blockage and corrosion damage to the lines, and on the other hand, ensures good energy integration of the system through the recovery and reuse of heat from the gases. For example, if nitrogen preheating is not used, the heat from the gases circulating in the exhaust line 7 can be used for the low-temperature drying (-100°C) of biomass with intermediate moisture content (a few tens of percent).

[0058] According to an advantageous possibility, the system includes heating said gas exhaust pipe 7 so as to prevent condensation of the gases from taking place in the pipe, thus eliminating the risk of liquid tar flowing back by gravity into the tank 1. Preferably, the heating of the gas exhaust pipe 7 is for example carried out by a heating cord 16 arranged on the gas exhaust pipe 7 between the tank 1 and the thermal energy recovery module 8, upstream of the condenser 9.

[0059] The system may include a storage tank for the liquefied gases 13 by passing through the condenser 9. Advantageously, the tank is arranged below the condenser 9 so as to ensure gravity storage of the liquefied gases.

[0060] The system may include a dry gas storage tank 12 corresponding to the gases remaining after passing through the condenser 9.

[0061] In one configuration, the system includes a mixer 4 arranged within tank 1. Mixer 4 is advantageously configured to operate on dry biomass with a particle size of a few millimeters or less, as well as on wet biomass. For example, mixer 4 is suitable for mixing liquid phases and dry granular media. Preferably, mixer 4 is selected from a paddle mixer and a rotary mixer, such as those offered by AGITEC. Mixer 4 ensures a homogeneous temperature of the biomass within tank 1.

[0062] According to one aspect of the invention, the system includes a biomass injection hopper 22 for supplying biomass to the tank 1.

[0063] The hopper 22 is advantageously at the same pressure as tank 1. This means that the hopper 22 and tank 1 have the same pressure. The hopper 22 is therefore suitable for pressurization to pressures between 1 bar and 100 bar (100 and 10,000 kPa). Advantageously, the pressure control module 3 is configured to control the pressure in the hopper 22. For this purpose, the hopper 22 may include a pressurized chamber, or pressurized airlock, at the same pressure as tank 1. The hopper 22 thus allows the tank 1 to be fed with biomass continuously or intermittently while ensuring that the pressure in tank 1 is not altered during the introduction of biomass. The half-angle of the hopper relative to the vertical is preferably between 10 and 25° to prevent any blockage of dry or wet biomass in the hopper. Preferably, the hopper will be made of stainless steel, in order to limit the roughness of its internal wall (standard 304 or 316L stainless steel).Hopper 22 is advantageously supplied with biomass.

[0064] According to one embodiment, the nitrogen supply line 6 in the tank 1 includes a branch 6a allowing the nitrogen supply to the hopper 22, to ensure its pressure equalization with the tank 1.

[0065] In one embodiment, the system includes an extraction opening 23 for the thermally converted biomass. The extraction opening 23 is advantageously located in the lower part of the tank 1. The extraction opening 23 is preferably at equal pressure with the tank 1 so as to allow the biomass to be extracted without depressurizing the tank 1. Similar to the hopper 22, the extraction opening 23 may include a depressurization chamber. The extraction opening 23 may be controlled by a solenoid valve.

[0066] In one scenario, the system includes a wet biomass feed line 19. Advantageously, the wet biomass feed line 19 terminates at the hopper 22, if one is present. Preferably, the system includes a pump 20 for pressurizing the wet biomass feed line 19.

[0067] In one option, the system includes a dry biomass feed line 21. Advantageously, the dry biomass feed line 21 terminates at the hopper 22, if one is present. Preferably, the system includes a metering screw for feeding biomass into the hopper 21. The metering screw is maintained under slight positive pressure with an inert gas, advantageously nitrogen, facilitating the flow of biomass from the metering screw into the hopper 22.

[0068] According to one embodiment, the tank 1 includes a lid, not shown, allowing the introduction of biomass into the tank 1 or at least an access for maintenance in the presence of a hopper 22 and an extraction opening 23.

[0069] According to one aspect, the invention relates to a process for the thermo conversion of biomass using a system as described above.

[0070] Advantageously, the biomass thermo conversion process according to the invention allows the use of a single system as described above to implement alternatively a first thermoconversion mode by torrefaction and a second thermoconversion mode by hydrothermal carbonization.

[0071] The system according to the invention is thus flexible by allowing complementary modes of operation without modification or use of various systems.

[0072] Flexible means that the system according to the invention is capable of, and configured to, alternately operate according to a thermoconversion mode and a hydrothermal carbonization mode.

[0073] The system according to the invention allows the implementation of the biomass thermo conversion process according to the invention allowing the implementation alternatively of a first thermoconversion mode by torrefaction and a second thermoconversion mode by hydrothermal carbonization.

[0074] The process according to the invention includes an operating phase configured to adapt the operating mode of the system as described above according to a first mode of thermo conversion by torrefaction or according to a second mode of thermo conversion by hydrothermal carbonization according to at least one parameter of the biomass to be treated, in particular the percentage of moisture of the biomass to be treated.

[0075] Depending on the possibility, other parameters of the biomass to be treated can be taken into account such as the nature of the biomass, the cost of the biomass.

[0076] According to one possibility, other parameters of the system and process according to the invention can be taken into account such as the ease of implementation of the process, the operating cost of the process according to the roasting method or according to the hydrothermal carbonization method.

[0077] As an example, it may be advantageous to dry very cheap biomass and process it by torrefaction rather than increasing its moisture content by wetting it and processing it by hydrothermal carbonization, even if it has a high moisture content, because the torrefaction process is, for example, simpler to implement than hydrothermal carbonization.

[0078] Preferably, the biomass thermo-conversion process includes a preliminary step of determining the percentage of moisture in the biomass to be treated.

[0079] The preliminary step of determining the moisture content of the biomass to be treated can be carried out on the same site as the treatment area and the system, or on a different site prior to treatment. This preliminary step of determining the moisture content of the biomass to be treated can be performed by the system itself or by a separate module.

[0080] Traditionally, the determination of the percentage of moisture of the biomass to be treated is carried out on a sample of biomass to be treated by the use of a temperature-controlled oven which will allow the water to be extracted from the biomass and a precision balance which will allow the biomass to be weighed before and after drying in order to determine its moisture content.

[0081] In one scenario, the system includes a control unit configured to adapt the system's operation based on the moisture content of the biomass being processed. The control unit is configured to advantageously control at least one of the following: the pressure control module, the nitrogen distribution module (including nitrogen circulation in the bypass circuit for preheating), the gas extraction module, the hopper, the extraction opening, and the heating module.

[0082] The first torrefaction conversion method is implemented, advantageously by the control unit, when the biomass moisture content is, for example, less than or equal to a first moisture threshold, such as 25%. Depending on the scenario, this first moisture threshold, which defines the implementation of the first conversion method, is chosen based on the nature of the biomass and / or its cost and / or the cost of the process.

[0083] The second thermoconversion mode, using hydrothermal carbonization, is implemented, advantageously by the control unit, when the biomass moisture content is, for example, greater than or equal to a second moisture threshold, such as 65%. Depending on the scenario, this second moisture threshold, which defines the implementation of the first conversion mode, is chosen based on the nature of the biomass and / or its cost and / or the cost of the process.

[0084] Preferably, the system alternately implements the first conversion method by roasting and the second method of thermoconversion by hydrothermal carbonization. Preferably, the system does not successively implement the first method followed by the second method, nor the second method followed by the first method, on the same biomass to be processed.

[0085] When the percentage of moisture in the biomass is above a first threshold of percentage of moisture such as for example 25% and below a second threshold of percentage of moisture such as for example 65% then, a phase of upgrading the percentage of moisture in the biomass is carried out.

[0086] According to one possibility, the biomass moisture content adjustment phase involves increasing the biomass moisture content by adding water to the biomass to be treated, reaching a moisture content of at least 65%, or a second moisture content threshold such as, for example, less than 65% and potentially up to 90%. This moisture content adjustment phase is implemented, for example, for an initial biomass moisture content between 40% and 65%.

[0087] According to a second possibility, the biomass moisture content leveling phase involves reducing the biomass moisture content by drying the biomass to be processed to reach a first moisture content threshold, such as 25%. This moisture content leveling phase is implemented, for example, for an initial biomass moisture content between 25% and 40%. Drying can be carried out, for example, using the thermal energy from the extracted gases recovered by the heat recovery unit 24.

[0088] The first method of thermo conversion by roasting is described below.

[0089] This first method of thermo-conversion by roasting can be carried out continuously or in batches, i.e. discontinuously.

[0090] This first method of thermo-conversion by torrefaction involves filling tank 1 with the biomass to be treated. Preferably, the biomass to be treated has a moisture content of 25% or less.

[0091] According to a first embodiment corresponding to batch operation, tank 1 is filled at the beginning of the process either by opening the lid if it is present, or through the hopper 22. Once tank 1 is filled, the lid is replaced or the hopper is closed.

[0092] According to a second embodiment corresponding to continuous operation, the tank 1 is continuously filled during the process, advantageously by the hopper 22.

[0093] The first mode of thermo conversion by roasting includes mixing the biomass by mixer 4. Advantageously, the mixing of the biomass by mixer 4 is carried out throughout the thermo conversion.

[0094] The first mode of thermo conversion by roasting includes the injection of nitrogen by the nitrogen injection module into the system more precisely into tank 1. This nitrogen injection ensures an inert environment in tank 1 and therefore a nitrogen gas ceiling.

[0095] In one scenario, at least tank 1 is pressurized to a pressure slightly above atmospheric pressure, such as 1.2 bar (120 kPa). A slight overpressure is advantageously maintained in tank 1 to compensate for linear and singular pressure losses related to conveying and injection during continuous operation. Advantageously, gas extraction is carried out continuously to maintain a pressure close to the defined pressure throughout the process and avoid overpressure in tank 1.

[0096] The first thermo conversion method by torrefaction involves heating the biomass to be treated in tank 1 to a temperature between 200 °C and 300 °C by the heating module 5.

[0097] The first method of thermal conversion by roasting involves the extraction of gases from the upper part of tank 1 by the gas extraction module. The extracted gases are a mixture of nitrogen and gases produced during thermal conversion. Advantageously, the gases extracted from tank 1 are condensed by the condenser 9 of the gas extraction module.

[0098] The first mode of thermo conversion by roasting includes the recovery of thermal energy from the extracted gases for the preheating of the nitrogen injected into the tank 1.

[0099] Pressurization, mixing, gas extraction and temperature maintenance are advantageously maintained throughout the entire thermo-conversion of biomass.

[0100] The first method of thermo-conversion by torrefaction involves the extraction of biomass converted into biochar. Extraction is carried out after a predefined residence time, for example, between 15 and 120 minutes, corresponding to the time required for the thermo-conversion of the biomass.

[0101] According to a first embodiment corresponding to batch operation, the tank 1 is opened or the extraction opening 23 is opened at the end of the predefined residence time and the biochar is recovered.

[0102] According to a second embodiment corresponding to continuous operation, the extraction of biomass converted into biochar is carried out simultaneously with pressurization, mixing, gas extraction, and temperature maintenance. The extraction opening 23 is opened according to a scheme allowing sufficient residence time for the thermo-conversion of the biomass.

[0103] The second mode of thermo conversion by hydrothermal carbonization is described below.

[0104] This second mode of thermo conversion by hydrothermal carbonization can be carried out continuously or in batches, i.e. discontinuously.

[0105] This second method of thermo-conversion by hydrothermal carbonization involves filling tank 1 with the biomass to be treated. Preferably, the biomass to be treated has a moisture content greater than or equal to 65%.

[0106] According to a first embodiment corresponding to batch operation, the tank 1 is filled at the beginning of the process either by opening the lid if it is present, or through the hopper 22. Once the tank 1 is filled, the lid is replaced or the hopper 22 is closed.

[0107] According to a second embodiment corresponding to continuous operation, the tank 1 is continuously filled during the process, advantageously by the hopper 22.

[0108] The second mode of thermo conversion by hydrothermal carbonization includes mixing of the biomass by mixer 4. Advantageously, the mixing of the biomass by mixer 4 is carried out throughout the thermo conversion.

[0109] The second mode of thermoconversion by hydrothermal carbonization involves injecting nitrogen into tank 1 using the nitrogen injection module. This nitrogen injection ensures an inert environment within tank 1, resulting in a nitrogen gas headspace. Advantageously, this second mode of thermoconversion by hydrothermal carbonization includes, after tank filling, nitrogen purging. Nitrogen purging consists of circulating nitrogen through the tank to ensure the presence of only inert gas.

[0110] In one scenario, at least tank 1 is pressurized to a pressure greater than or equal to 15 bar (1500 kPa), preferably in the range of 100 bar (10000 kPa). Preferably, pressurization is carried out after the flushing step. Several nitrogen flushes are therefore performed before pressurization.

[0111] The second mode of thermo conversion by hydrothermal carbonization includes heating the biomass to be treated in tank 1 to a temperature between 180°C and 260°C by the heating module 5.

[0112] The second thermo-conversion method by hydrothermal carbonization does not include gas extraction from the upper part of tank 1. In this second thermo-conversion method, tank 1 is maintained under pressure without gas extraction. Gas extraction is carried out at the end of the hydrothermal carbonization process.

[0113] Pressurization, mixing, and temperature maintenance are advantageously maintained throughout the entire thermo-conversion of biomass.

[0114] The second mode of thermo conversion by hydrothermal carbonization includes, after a predefined residence time, for example between a few minutes and several hours corresponding to the time required for the thermoconversion of the biomass, the extraction of the biomass converted into hydrochar.

[0115] According to a first embodiment corresponding to batch operation, the tank 1 is opened or the extraction opening 23 is opened at the end of the predefined residence time and the hydrochar is recovered.

[0116] According to a second embodiment corresponding to continuous operation, the extraction of biomass converted into hydrochar is carried out simultaneously with pressurization, mixing, and temperature maintenance. Gas extraction is continuous, and pressure is maintained using pressure regulating valves. The extraction opening 23 is opened according to a scheme that allows sufficient residence time for the thermoconversion of the biomass.

[0117] Advantageously, the second mode of thermo conversion by hydrothermal carbonization according to the invention works under an advantageously dry inert atmosphere, that is to say under an inert gas preferably nitrogen instead of working under an atmosphere of water or water vapor as the prior art.

[0118] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention. LIST OF REFERENCES

[0119] 1. Tank 3. Pressure control module 4. Mixer 5. Heating module 6. Nitrogen supply line 6a. Bypass 7. Extracted gas exhaust line 8. Thermal energy recovery module 9. Condenser 10. Expansion valve 11. Pressure gauge 12. Condensate gas storage tank 13. Dry gas storage tank 14. Distribution plate 15. Distribution opening 16. Heating cable 17. Nitrogen preheating bypass line 18. Preheated nitrogen return line 19. Wet biomass feed line 20. Pump 21. Dry biomass feed line 22. Hopper 23. Extraction module 24. Heat exchanger

Claims

1. Flexible biomass thermoconversion system by torrefaction or hydrothermal carbonization comprising - a tank (1) intended to be closed and to receive biomass and a gas head, - a nitrogen distribution module in the tank (1), - a heating module (5) intended to heat the biomass contained in the tank (1), - a pressure control module (3) at least in the tank (1), characterized in thatthe nitrogen distribution module includes a distribution plate (14) comprising a distribution chamber provided with nitrogen distribution openings (15) and the system includes a control unit configured to adapt the operation of the system according to the percentage of moisture of the biomass to be treated to take alternatively a first mode of thermoconversion by torrefaction when the percentage of moisture of the biomass to be treated is less than a first predefined threshold or a second mode of thermoconversion by hydrothermal carbonization when the percentage of moisture of the biomass to be treated is greater than a second predefined threshold.

2. System according to the preceding claim wherein the first predefined threshold of percentage moisture of the biomass to be treated is 25% and the second predefined threshold of percentage moisture of the biomass to be treated is 65%.

3. System according to any one of the preceding claims comprising an injection hopper (22) for supplying the tank (1) with biomass, the hopper (22) and the tank (1) being at equal pressure, preferably the hopper (22) comprising a chamber pressurized at the pressure of the tank (1).

4. System according to any one of the preceding claims comprising a gas extraction module out of the tank (1) arranged in the upper part of the tank (1) comprising a gas extraction line (7), and preferably a heater for said gas extraction line.

5. System according to the preceding claim comprising a thermal energy recovery module (8) of the extracted gases including a thermal energy recuperator (24) intended to recover the thermal energy of the extracted gases for the benefit of preheating the nitrogen intended to be distributed in the tank (1), preferably the thermal energy recovery module of the extracted gases includes a condenser (9) intended to ensure the condensation of the extracted gases arranged upstream of the recuperator (24).

6. System according to any one of the preceding claims wherein the control unit is configured to control at least one of the pressure control module, nitrogen distribution module, gas extraction module, hopper, extraction opening, heating module.

7. Biomass thermoconversion process adapted to the moisture content of the biomass to be processed characterized in thatIt includes a preliminary step of determining the percentage of moisture of the biomass to be treated and an operating phase of a thermoconversion system according to any one of the preceding claims following a first mode of thermoconversion by torrefaction or a second mode of thermoconversion by hydrothermal carbonization depending on the percentage of moisture of the biomass to be treated previously determined.

8. A biomass thermoconversion process according to the preceding claim, wherein the first thermoconversion mode by torrefaction is activated for a biomass moisture percentage of less than 25%.

9. A biomass thermoconversion process according to any one of the two preceding claims, wherein the second thermoconversion mode by hydrothermal carbonization is activated for a biomass moisture percentage greater than 65%.

10. A biomass thermoconversion process according to any one of the three preceding claims comprising a phase of upgrading the percentage of biomass moisture prior to the operating phase if the percentage of biomass moisture determined by the preliminary determination step is between 25% and 65%.

11. A biomass thermoconversion process according to the preceding claim, wherein the phase of upgrading the percentage of biomass moisture comprises either increasing the percentage of moisture by adding water to the biomass to achieve a percentage of biomass moisture greater than 65% or decreasing the percentage of moisture by drying the biomass to achieve a percentage of biomass moisture of 25%.

12. A method for the thermoconversion of biomass according to any one of the four preceding claims, wherein the first method of thermoconversion by torrefaction comprises: - filling the tank (1) with biomass having a biomass moisture percentage greater than a first threshold of 25%, - mixing the biomass by a mixer (4), - injecting nitrogen by the nitrogen injection module into the tank (1) and pressurizing the tank (1) to a pressure of 1.2 bar (120 kPa), - heating the biomass to a temperature between 200°C and 300°C by the heating module (5), - extracting the gases from the upper part of the tank (1) by the gas extraction module, - condensing the gases extracted from the tank (1) by the condenser (9) of the gas extraction module, - extracting the thermoconverted biomass into biochar.

13. Method according to the preceding claim comprising a recovery of thermal energy from the extracted gases for preheating the nitrogen injected into the tank by the recuperator (24).

14. A process for the thermoconversion of biomass according to any one of the six preceding claims, wherein the second mode of thermoconversion by hydrothermal carbonization comprises: - filling the tank (1) with biomass having a biomass moisture percentage greater than a second threshold of 65%, - purging the tank (1) with nitrogen, - injecting nitrogen by the nitrogen injection module into the tank (1) and pressurizing the tank (1) to a pressure of 15 to 50 bar (1500 to 5000 kPa), - mixing the biomass by a mixer (4), - heating the biomass to a temperature between 180°C and 260°C by the heating module (5), - extracting the thermoconverted biomass into hydrobiochar.

15. A biomass conversion process according to any one of the two preceding claims, wherein the filling of the biomass and the extraction of the biomass are continuous.

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