Hydrothermal carbonization process

Abstract

The invention relates to a hydrothermal carbonization process of a biomass comprising organic matter, said process comprising: - injecting said biomass, a heat carrier fluid and a reagent into a reactor (1); - making circulate a mixture constituted of said biomass, said heat carrier fluid and said reagent under specific pressure and temperature conditions allowing the conversion of organic matter by hydrothermal carbonization. The invention comprises: 1) determining the emitted gas yield T e during the hydrothermal carbonization reaction, 2) comparing the determined emitted gas yield T e with a predetermined set gas yield T c , and 3) adjusting at least one of the reaction operating parameters selected from the temperature within said reactor (1), the amount of reagent injected, and the residence time in said reactor (1), to adjust the emitted gas yield T e so that the value of this emitted gas yield T e tends to be equal to the value of the set gas yield T c . The invention is applicable to the treatment of a biomass comprising organic matter.

Description

TECHNICAL FIELD

[0001] The present invention relates to a thermal conditioning process using the thermo-chemical reaction of hydrothermal carbonization. BACKGROUND

[0002] Hydrothermal carbonization is a well-known reaction, abbreviated as HTC (for HydroThermal Carbonization in English), which is a natural reaction occurring at high temperature and high pressure in the depths of the Earth. It is based on the production of coal and natural gas from biomass. Hydrothermal carbonization, also noted HTC, has been transposed to an industrial environment by thermal conditioning for a substantial improvement of the dewatering of biomass, such as sludge from wastewater treatment plants or organic waste, to transform it into high added-value products.

[0003] The thermal conditioning, the heart of the process, is carried out at high temperature, between 175°C and 260°C, and generally in an autoclave at high pressure, usually between 9 and 50 bars, i.e. approximately 1 and 5 MPa, for a duration generally between 5 minutes and 12 hours. Depending on the dewatering equipment located downstream of the thermal conditioning, the temperature and the pressure applied by the HTC reaction, the biomass is easily dewatered by mechanical dewatering and transformed into biochar. The slightly exothermic reaction is accelerated by the addition of a catalyst, for example due to the presence of: an acid (such as citric acid or sulfuric acid or acetic acid), or a base (such as caustic soda).

[0004] Overall, the HTC reaction can be represented in the following form:

[0005] C n H m O p → C x H y O z + a H2O + b CO2,

[0006] This thermo-chemical reaction changes the macromolecular and molecular arrangement, the result of which is to make the material more hydrophobic, in particular concentrating carbon atoms, and thus the intrinsic calorific value. The significant increase in the hydrophobicity of the organic matter makes it easier to dewater in a subsequent step, such as mechanical pressing or centrifugation.

[0007] This process is particularly used to dewater sludge from wastewater treatment plants to a very high dry matter level. Indeed, when the thermal conditioning step is combined with a later dewatering step, it is possible to reach, for example, a dry matter content level of about 70%. This is why the combination of hydrothermal carbonization with a later dewatering step is called "superdewatering".

[0008] Before superdewatering of wastewater sludge, this high dryness could only be achieved by drying methods, mainly thermal drying methods, which are very energy-intensive, despite improvements in these processes.

[0009] On the contrary, depending on the content and the nature of the organic matter present in the sludge, mechanical dewatering alone by low energy consumption, pressure application, cannot exceed 35% to 40% without coupling with the hydrothermal carbonization reaction.

[0010] The dewatering quality controlled by the thermal regulation of the hydrothermal carbonization reaction is closely linked at this level to the operating conditions applied, in other words to the good implementation of the minimum progress of the HTC reaction. The kinetics of this HTC reaction depend on the residence time of the products in the reactor, the temperature and pressure levels, as well as the amount of reagents produced, but also on the nature of the biomass introduced into the reactor. These factors also depend on the quality and the properties of the biochar obtained, in particular after the subsequent post-dewatering step.

[0011] However, when setting the regulation of the HTC step, the result of the dewatering, and in particular the dryness of the "super-dewatered" sludge, is only perceived after several hours of passage of the sludge through the HTC reactor.

[0012] Thus, it is only possible to judge a posteriori whether the effectiveness of the HTC reaction is sufficient, that is to say after the subsequent post-dewatering step (for example on the so-called carbonized product by mechanical pressing, it is then called filter cake).

[0013] In addition, the quality of the sewage sludge treated by HTC varies over time, in particular the dryness. However, the dry matter rate measured directly upstream of the hydrothermal carbonization reactor does not allow to predict the rate of organic matter involved in the carbonization reaction in this case. The measurement of the volatile matter is generally known more than 24 hours after sampling. Indeed, the sample must be placed in an oven at 105°C for 24 hours to know its dryness. The same sample is then passed through an oven at 550°C for 2 hours to burn the organic part of the dry matter.

[0014] Currently, the solution for monitoring the HTC reaction progress is based on the measurement of the pH at the outlet of the reactor, preferably after the heat exchanger for cooling the sludge, i.e. 2 to 3 hours after the injection of the sludge and the reagents into the HTC reactor. However, this measurement is not sufficient to predict a good final dewatering. The dewatering quality is obtained after the operation of pressing the dewatered material into the form of filter cake, only the analysis of this filter cake allowing to determine the super-dewatering (HTC + post-dewatering) performance and sequence. The time from the entry of the sludge into the reactor to the analysis of the dewatered filter cake can exceed 10 hours. It also depends largely on the storage of the carbonized sludge leaving the reactor. In addition, the storage mixes the carbonized sludge and homogenizes the production over several hours. Thus, the pH measurement is not a sufficiently accurate indicator of the achievable dewatering level.

[0015] If the dewatering performance is found to be insufficient, it is possible to increase, among others, the amount of reagents, the residence time in the reactor or even the heating temperature of the reactor, etc. Conversely, in order to quantify the impact related to one of the three parameters, it is necessary to wait for several final dewatering batches, especially due to the different downstream storage steps.

[0016] In other words, the dewatering performance and thus the dryness of the filter cake of the dewatered substance are therefore the result of adjustments made nearly 24 hours earlier. Therefore, by optimizing the reactor operating parameters to shorten, even eliminate, this delay time, it would constitute a clear improvement in the productivity of the technical industry to thereby obtain real-time control of its performance.

[0017] To try to solve this problem, various techniques have thus been developed.

[0018] Document US-A-10308887 thus demonstrates that, during the hydrothermal carbonization process, the biomass is converted into biochar. The reaction yield depends on the reaction conditions, among which the duration of the carbonization reaction or the length of time during which the slurry composed of water and biomass is retained in the reaction vessel and exposed to the pressure and temperature. These conditions should be chosen to obtain a residue as dry as possible. It has been demonstrated that the variation in the amount of dry residue during the course of the carbonization reaction shows a curve that is largely similar to that of the pH of the treated biomass, which is easier to monitor than the dry residue during the ongoing reaction. However, measuring the pH of the carbonized sludge remains difficult to carry out directly in the reactor, since there is no instrument capable of withstanding the temperature and pressure inside the reactor.

[0019] The analysis of the pH is then most often carried out downstream of the reactor, after relaxation to atmospheric pressure and to a temperature much lower than 100°C. The measurement requires periodic calibration of the pH probe.

[0020] The indicator of the pH of the carbonized sludge is thus an indirect and a posteriori indication of the progress of the reaction in the reactor and in the industrial phase of continuous production of carbonized sludge. As mentioned above, such adjustments cannot predict the effects produced quickly enough.

[0021] A hydrothermal carbonization reaction aiming at obtaining an optimal yield of certain substances, in particular a carbon yield as high as possible, is described in US2015 / 0259209. Different types and qualities of biomass are treated by this process so that the reaction can occur in each individual batch in very different ways. Influencing the process is generally problematic, since the process is carried out in a closed manner. For this reason, a shunt is defined which allows process water to pass through, in which a sensor for determining the total organic carbon relative to the dissolved carbon is placed. Adjustments to the process parameters can then be made manually or by a process controller depending on the measurements of the sensor. Faster control and regulation are thus carried out, but specific equipment must be implemented.

[0022] In DE 102016125286 it is proposed to recover gaseous and liquid compounds degraded by condensation reaction in order to be able to subsequently analyze them and send the results to a manipulation system which allows to adjust the reactor according to these data. Likewise, it is necessary to delay several hours to perform this analysis. Another defect lies in the volume of compounds, not indicated in this patent, but which is inseparable from the degree of reaction.

[0023] Therefore, to date, there is no known system which allows to adjust in real time the HTC reaction in the reactor without significant modifications to the existing equipment. However, in the case of industrial deployment, the need to adjust such a process in real time is great. Therefore, it is precisely to extend and optimize this process that the present invention has been developed. SUMMARY

[0024] The object of the present invention is to remedy the defects of the prior art by proposing a method which allows to monitor the HTC reaction progress and to adjust almost in "real time" said HTC reaction in the reactor.

[0025] The present invention thus relates to a hydrothermal carbonization method of a biomass comprising organic matter, said method comprising:

[0026] - injecting biomass, heat carrier fluid and reagent into a reactor;

[0027] - circulating a mixture consisting of biomass, heat carrier fluid and reagent under specific pressure and temperature conditions allowing the conversion of organic matter by hydrothermal carbonization, characterized in that:

[0028] 1) determining the emission gas yield T e ,

[0029] 2) comparing the determined emission gas yield T e with a predetermined set gas yield T c , and

[0030] 3) adjusting at least one of the reaction manipulation parameters selected from the temperature within the reactor, the amount of reagent injected, and the residence time in the reactor, to adjust the emission gas yield T e so that the value of this emission gas yield T e tends to equal the value of the set gas yield T c .

[0031] In the sense of the present invention, biomass comprises organic matter. This can in particular relate to organic waste and / or sludge, in particular sludge of sewage treatment plants, industrial or municipal wastewater.

[0032] In the following, the biomass entering the step or the HTC reactor will be called "input biomass" ("input sludge"), the biomass output from the HTC step will be called "carbonized biomass". In case the method of the application comprises a subsequent dewatering step, the product of this step will be called "dewatered biomass" or "super-dewatered biomass".

[0033] As mentioned above, the organic matter of the biomass is transformed when it is subjected to the specific pressure and temperature conditions in the HTC reactor. This transformation includes hydrolysis, followed by parallel decarboxylation and dewatering of the organic matter from its own constituents.

[0034] It can be noted that a part of the organic matter of the input biomass "disappears" - dissolved and solid fraction - from the carbonized product measured at the outlet of the reactor, in the following proportions:

[0035] • 35% to 55% of O;

[0036] • 3% to 7% of H;

[0037] • 1% to 5% of C.

[0038] The mass balance shows that 70% to 90% of the O2 that disappeared is consumed by the traditional oxidation-reduction reaction that generates CO2 and H2O from C and H.

[0039] However, it is difficult to determine the exact balance of the C, H and O elements, because a part of the gas formed during the HTC reaction remains dissolved in the liquid fraction, to be released after the wait in the batch storing the carbonized biomass. However, these dissolved gases and gaseous gases are in equilibrium and vary in the same direction. The water vapor formed by the HTC reaction cannot be distinguished from the water vapor coming from the evaporation of the water contained in the input biomass. Thus, a part of the gas produced by the HTC reaction is at the outlet of the reactor - the part that can be measured - while the soluble part is at the carbonized biomass storage tank, and cannot be measured.

[0040] However, the inventors have demonstrated that this part of gas emitted in the reactor is correlated with the degree of progress of the HTC reaction in progress. The inventors have also established a correlation between the emission gas yield and, more specifically, the emission gas flow (which is directly measurable by the non-condensable gas flow measured at the outlet of the reactor, or indirectly by the pressure difference in the pressure measured at the end and at the beginning of the reaction (this pressure difference resulting from the transformation of the matter, and thus from the reaction progress)) and thus between the emission gas flow or the pressure in the reactor and the dewatered biomass dryness rate.

[0041] Based on experimental measurements, the inventors have actually been able to establish a mathematical relationship between the final pressure of the non-condensable gases in the reactor and the dryness in a batchwise process: Ln P = f(Ln(TS / (0,0001-TS)), with f(x) = -0,03226 ＊ x + 10,8734

[0042] wherein:

[0043] - P: represents the final pressure in the hydrothermal carbonization reactor at 75°C (in Pa), which corresponds to the gas production of the HTC reaction; and

[0044] - TS: final filter cake dryness, in g / L.

[0045] Thereby, in a batchwise implemented process, the amount of emitted gases increases with the degree of progress of the reaction causing higher pressures. The pressure variations thereby reveal variations in the progress and / or performance of the reaction, which can be acted upon by adjusting one or more reaction parameters, such as the amount of injected reagents.

[0046] Thereby, in a continuously implemented process, the amount of emitted gases increases with the degree of progress of the reaction at constant pressure and causes greater gas flow. The variations in the flow of emitted gases thereby reveal variations in the progress and / or performance of the reaction, which can be acted upon by adjusting one or more reaction parameters, such as the amount of injected reagents. The temperature within the reactor can also be adjusted by controlling the temperature of the heat carrier fluid and / or by adjusting the input biomass flow to adjust the residence time in the reactor.

[0047] Thereby, the reaction progress indicator is the emitted gas yield, more particularly the yield of so-called non-condensable gases, which is related by chemical reaction to the stoichiometric conditions.

[0048] In the case of a batch HTC process, the emitted gas yield T is determined based on the pressure measurements within the reactor during the batch, more particularly at the end of the batch, and more particularly at the end of the period of carbonization and cooling at the fixed target temperature. e Indeed, the equipment used is completely sealed, the production of reaction gases, and therefore of emitted gases, being revealed by the final pressure in the reactor. The initial amount of product produced is constant, the initial pressure being equal to ambient air. Any overpressure after the reaction thus originates from the gases remaining in the reactor, the saturation pressure of which is much lower than that of water. More particularly, the partial pressure of water at a given temperature is constant and known, knowing the temperature and pressure in the reactor at the end of the batch allows to precisely calculate the overpressure related to the production of non-condensable gases by the HTC reaction. At the end of the batch, the pressure or overpressure of the non-condensable gases present in the reactor thereby gives the emitted gas yield Te Directly related. According to an advantageous embodiment, the pressure in the reactor will be measured at the end of the batch and after cooling to a predetermined temperature (e.g., 75°C or 70°C).

[0049] Advantageously, measuring the exhaust gas flow rate or the pressure in the reactor during the HTC reaction is sufficient to indicate the progress of the carbonization reaction in the reactor. Therefore, for continuous processes, the temperature parameters in the reactor (by changing the temperature of the steam or heat transfer fluid), the amount of reagent injected (in or upstream of the reactor), and / or the residence time of biomass in the reactor, especially by changing the flow rate of the input biomass, can be varied to allow either improved dehydration or optimized reagent consumption. For batch processes, these same reaction parameters can be adjusted for subsequent batches.

[0050] In the case of a continuously implemented HTC process, the emission gas yield T is determined by measuring the flow rate of the non-condensable gas emitted at the reactor outlet (directly at the reactor outlet). e Therefore, more specifically, the emission gas yield T is calculated based on the flow rate of the non-condensable gas emitted at the reactor outlet. e .

[0051] Therefore, the method according to the invention, when implemented continuously, allows for the advantageous real-time adjustment of the reaction temperature and / or the amount of reagent injected and / or the residence time in the reactor, in a manner easily implemented throughout the HTC reaction, by measuring the exhaust gas flow rate at the reactor outlet and comparing it with a set gas flow rate value, the measurement being performed at the reactor outlet rather than inside.

[0052] Measuring the exhaust gas flow rate during the reaction is preferably performed at the reactor outlet. When the HTC step is continuous, the exhaust gas flow rate is preferably measured using a flow meter. Preferably, the measurement of the exhaust gas flow rate at the reactor outlet is performed after the exhaust gas has passed through a gas dehydration or condensation device (e.g., a condenser of the "scrubber" type, in particular). This allows water vapor to condense, and primarily measures the exhaust gas, which is referred to as "non-condensable," thus improving measurement accuracy. A water-absorbing dehydration filter, such as a zeolite filter, can also be used to achieve the same effect, retaining water vapor so that only the non-condensable portion of the exhaust gas passes through.

[0053] When the method according to the invention is implemented in batches, it advantageously allows for the adjustment of the reaction temperature and / or the amount of reagent injected and / or the residence time for subsequent batches by measuring the pressure inside the reactor and comparing it with a set pressure. Thus, in order to achieve the set pressure in subsequent batches, the residence time in the reactor can be adjusted by controlling the reaction time of the batching method, and / or the temperature inside the reactor can be adjusted by cooling the sealed reactor through heat exchange with a heat transfer fluid permeating the walls of the reactor or the coil.

[0054] The heat transfer fluid is usually water, especially water in the form of steam.

[0055] The reagent is typically a catalyst that allows the HTC reaction to be initiated and can be self-sustaining after the HTC reaction. Examples of catalysts are, in particular, organic or inorganic acids or bases. Acid catalysts are preferably selected from sulfuric acid and straight-chain or branched C1-C6 carboxylic acids, especially straight-chain or branched C1-C6 mono, di, and di or tricarboxylic acids, such as formic acid, acetic acid, and citric acid.

[0056] Hydrothermal carbonization is well known to those skilled in the art, who will be able to select operating ranges for reaction parameters such as temperature, pressure, and residence time. Preferably, the HTC step is carried out at a high temperature of 150°C to 300°C, preferably 175°C to 260°C, and generally at a pressure of typically 10 bar to 50 bar (i.e., about 1 MPa to 5 MPa), for a duration typically from 5 minutes to 12 hours, preferably 1 hour to 3 hours.

[0057] Advantageously, the hydrothermal carbonization method according to the invention includes implementing additional different steps. In particular, a pre-step is preferably implemented in which the gas flow rate D is selected and set according to the desired dryness of the final product. c Or set the pressure P c The value. For example, by using an established correlation table between gas flow rate (especially CO2) / pressure and dryness.

[0058] Alternatively, when operating equipment used to implement the HTC reaction, testing can be performed to obtain a target dryness fraction (e.g., 65%) by fixing one or more parameters, such as temperature and residence time (among others, flow rate), and in this case, the exhaust gas flow rate is measured, which becomes the set gas flow rate D. c This returns to calibration performed at constant temperature and residence time, with the variable parameter being the amount of reagent. In subsequent operations, if the measured exhaust gas flow rate D... e Deviation from set value D cThe dose of reagent can be adjusted to approach said set value until returning to said set value. Advantageously, the adjustment of the quantity of reagent will be implemented by successive increases and / or decreases, in particular to avoid a loss of control of the reaction.

[0059] The predetermined value of the gas flow "D c " (set gas flow) can be input into the control and handling means of the apparatus for implementing the hydrothermal carbonization process. During the HTC reaction, advantageously after the post-dehydration step, the flow of exhaust gas "D e " at the outlet of the HTC reactor is measured, preferably at regular intervals or continuously, and the value of the measured exhaust gas flow D e is compared to the value of the set gas flow D c (+ / - X%). If the exhaust gas flow D e differs from the set gas flow D c , at least one of the following three parameters will be adjusted:

[0060] • the quantity of reagent injected (in particular the HTC reaction catalyst, preferably an acid catalyst such as citric acid),

[0061] • the temperature T within the reactor, and / or

[0062] • the residence time in the HTC reactor,

[0063] in order to adjust the value of this exhaust gas flow D e so that it is either equal to the value of the set gas flow D c or approaches said value of D c . If the new value D e is not always equal to the value of D c after the measurement of the exhaust gas flow, one of the reaction parameters is changed again, and so on (feedback loop).

[0064] In order, the quantity of reagent injected, the temperature T within the reactor, and finally the residence time are preferably adjusted.

[0065] The adjustment can be implemented manually or automatically.

[0066] The quantity of reagent injected is thus increased and / or decreased according to the measured flow.

[0067] The residence time can be changed by changing the flow rate of the biomass input in the reactor, and / or by changing the flow rate of the biomass in the reactor. Preferably, the residence time will be changed by changing the flow rate of the biomass input.

[0068] The temperature within the reactor can be changed by changing the temperature of the heat carrier fluid and / or of the biomass input. Preferably, the temperature of the heat carrier fluid will be changed.

[0069] According to one particular embodiment, the hydrothermal carbonization method further comprises a step of extracting at least one portion of the mixture contained in the reactor. In the case of a continuous method, this extraction is carried out continuously.

[0070] The subject of the application is also a method for dewatering biomass, comprising:

[0071] - a hydrothermal carbonization method of the biomass of the application, resulting in carbonized sludge; and

[0072] - a mechanical dewatering step of the carbonized sludge, resulting in dewatered sludge.

[0073] The mechanical dewatering step can comprise or consist of a compression step, in particular by piston press or filter press. This step can also comprise or consist of a centrifugation.

[0074] The dewatered sludge obtained advantageously has a dryness of between 40% and 70%, preferably between 60% and 70%.

[0075] The subject of the application is also a hydrothermal carbonization installation of biomass comprising organic matter, said installation comprising:

[0076] - a reactor, means for inputting biomass into the reactor, means for injecting a heat carrier fluid into the reactor and means for injecting a reagent into the reactor, means for circulating a mixture consisting of biomass, heat carrier fluid and reagent under specific pressure and temperature conditions allowing the conversion of organic matter by a hydrothermal carbonization reaction, means for outputting the gases discharged in the reactor, characterized in that

[0077] - it comprises means for determining the discharge gas yield during hydrothermal carbonization;

[0078] - means for comparing the determined discharge gas yield T e with the value of the set gas yield T c ; and

[0079] - means for controlling and piloting the installation, which allow to adjust at least one of the reaction piloting parameters (temperature within the reactor, quantity of injected reagent, and residence time in the reactor) in order to adjust the discharge gas yield T e , so that the value of the discharge gas yield T e tends to be equal to the value of the set gas yield T c .

[0080] In a hydrothermal carbonization plant adapted to run a continuous process, the means for determining the yield of off-gas comprise means for measuring the flow rate of off-gas at the outlet of the reactor. These measuring means preferably comprise a flow meter installed in the gas output duct.

[0081] Preferably, upstream of the means for measuring the flow rate of off-gas, condensation or dehydration means are provided, such as a condenser of the "scrubber" type in particular. A dehydration filter that absorbs water, such as a zeolite filter, can also be used.

[0082] In a hydrothermal carbonization plant adapted to run a batch process, the means for determining the yield of off-gas comprise means for measuring the pressure in the reactor at the end of the cycle.

[0083] Preferably, in order to regulate the temperature in the reactor, for a batch process, the plant comprises cooling means by indirect contact with the fluid in the reactor.

[0084] Advantageously, the plant comprises, downstream of the HTC reactor, a press comprising at least one biomass inlet, a biomass outlet, the biomass inlet of the press being in fluid communication with the carbonized sludge outlet of the HTC reactor. BRIEF DESCRIPTION OF DRAWINGS

[0085] Other advantages and features of the application will become apparent from a reading of the following detailed description in conjunction with the accompanying drawings, of which:

[0086] - Figure 1 is a schematic view of an embodiment of a biomass continuous hydrothermal carbonization plant according to the application;

[0087] - Figure 2 is a graphical representation showing the variation of the dehydration performance and of the flow rate of reaction gas and of the quantity of reagent for a plant allowing to implement a method implemented continuously;

[0088] - Figure 3 is a graphical representation of the mathematical relationship between the final cake dryness of an HTC reactor implementing a batch carbonization method and the final pressure at 75°C. DETAILED DESCRIPTION

[0089] Figure 1 The plant shown comprises a reactor 1 provided to implement a hydrothermal reaction. The following of the present description will relate to an embodiment with sludge, but other types of biomass such as organic waste can be implemented.

[0090] The hydrothermal reaction comprises the following steps:

[0091] - a step of injection of sludge, in which a sludge is injected into the reactor 1 through a first inlet 11 ;

[0092] - a step of injecting steam as heat carrier fluid, in which steam is injected into the reactor 1 through a second inlet 12, which is preferably different from the first inlet 11 ;

[0093] - a circulation step, in which the mixture consisting of sludge and steam injected into the reactor 1 is made to circulate in the reactor 1,

[0094] - a step of continuously extracting at least a portion of the mixture contained in the reactor 1 through a sludge outlet 14.

[0095] The sludge containing organic matter comes, for example, from a hopper 2 to be directed into a pipe (inlet 11 of the plant) for example by gravity. The sludge reaching the pipe generally has a dry matter weight consistency of 10% to 30%, generally 18% to 24%.

[0096] The internal space of the reactor 1 is also configured to form a degassing volume 13 in an upper portion of the internal space, i.e. a portion having a higher height than the other portions of the internal space. In this degassing volume 13, the mixture is not circulated. This degassing volume 13 is provided to recover non-condensable gases, in particular CO2.

[0097] The reactor 1 is also provided with a non-condensable outlet connecting the degassing volume 13 to a discharge pipe 15 for a possible subsequent treatment. This non-condensable outlet is operated by a valve 16 to control the pressure in the reactor 1.

[0098] At the degassing volume or pipe 15, for example downstream of the pipe 15, preferably after a condenser 17, a device 2 for measuring the gas flow is installed, for example a flowmeter 18, thus allowing to measure the discharge gas flow D e .

[0099] In implementing the method according to the application, the following steps are followed:

[0100] During a preliminary step, called step 0, the set flow value D c is chosen according to the desired dewatering consistency of the biomass and this predetermined value of the gas flow "D c " (set flow) is entered in the control device of the plant, then the HTC reaction, preferably "hyperdewatering", is implemented as described above.

[0101] During the hydrothermal reaction, the discharge gas flow "D e " is measured, preferably at regular intervals or continuously. The flow measurement of the discharge gas is processed by the control and operating device by which the value of the discharge gas flow D e is compared to the set gas flow D cvalue comparison (+ / - X %). According to the exhaust gas flow D e value and the set gas flow D c value, at least one of the three parameters is adjusted, for example by controlling the input of the heat carrier fluid 12, the temperature T within the reactor 1 and / or, preferably, the amount of reagent injected into the reactor 1 from the reagent container 3 and / or the residence time in the HTC reactor 1.

[0102] The adjustment of at least one of these parameters thus allows the value of the D e to be changed so that it is equal to D c or at least close to D c . This adjustment step is iterated throughout the hydrothermal reaction (feedback loop), the subsequent measurement allowing the exhaust gas flow D e to be controlled to correspond to the set gas flow D c or the operating parameters to be adjusted until the exhaust gas flow D e and the set gas flow D c correspond to one another.

[0103] As can be seen in the foregoing, the stability and quality of the sludge input into the plant allow the link between the dewatering performance and the amount of injected reagent to be seen clearly. The reagent is a catalyst for the HTC reaction, in particular an acid catalyst chosen from citric acid, formic acid, sulfuric acid, acetic acid.

[0104] Figure 2 is a graphic representation showing the variation in dewatering performance and in the exhaust flow of non-condensable gases (denoted NC) from the reactor for a continuous hydrothermal carbonization process, in which the amount of injected reagent is adjustable while the other parameters are fixed, for example a constant reaction time of 2 hours 30 minutes, a constant reaction temperature of 185°C and a single type of sludge to be treated.

[0105] The mathematical relationship between the final cake dryness and the final pressure at 75°C for a 3-liter HTC micro-plant run in batches is shown in Figure 3 .

[0106] The HTC micro-plant is completely sealed, showing the production of reaction gases by the final pressure in the reactor. The test protocol is fixed, the initial amount of product is constant and the initial pressure is equal to the ambient pressure. Any higher pressure after the reaction results from the gases remaining in the reactor, which have a much higher saturation pressure than water.

[0107] The relationship thus obtained can be expressed by the following formula:

[0108] Ln(1 / P) = f(Ln((100-TS) / TS)), with f(x) = -0.3226 ＊x + 1.6631,

[0109] wherein:

[0110] - P represents the final pressure at 75°C in the hydrothermal carbonization reactor (in bar) which corresponds to the production of gas by HTC reaction, and

[0111] - TS represents the final dryness of the total solids % of the filter cake (expressed in %)

[0112] This formula is equivalent to the following one:

[0113] Ln P = f(Ln(TS / (0,0001-TS)), with f(x) = -03226 ＊ x + 10,8734,

[0114] wherein:

[0115] - P: represents the final pressure at 75°C in the hydrothermal carbonization reactor (in Pa) which corresponds to the production of gas by HTC reaction;

[0116] - TS: final filter cake dryness in g / L

[0117] The method according to the application thus allows to adjust in real time at least one functional parameter of the continuous hydrothermal carbonization process, and for the batchwise hydrothermal carbonization process, at least one functional parameter of the different batches. The adjustment method according to the application is thus optimized.

Claims

1. A method for hydrothermal carbonization of biomass containing organic matter, the method comprising: - Inject the biomass, heat transfer fluid and reagents into reactor (1); - In the reactor (1), under specific pressure and temperature conditions that allow for the conversion of organic matter by hydrothermal carbonization, a mixture consisting of the biomass, the heat transfer fluid, and the reagent is circulated, characterized in that: 1) Determine the emission gas yield T of the reactor (1) during the hydrothermal carbonization reaction. e , 2) The determined emission gas yield T of the reactor (1) e With the predetermined set gas yield T c Comparison, and 3) Adjust at least one of the following reaction control parameters: the temperature inside the reactor (1), the amount of reagent injected into the reactor (1), and the residence time in the reactor (1), to adjust the emission gas yield T. e So that the emission rate T e The value tends to be equal to the set gas yield T. c The value, During the steps prior to the hydrothermal carbonization reaction or during the HTC process, a predetermined gas flow rate value D is set based on the required dryness of the final product. c .

2. The method according to claim 1, characterized in that, The method is carried out continuously, and the emission gas yield T is determined by measuring the flow rate of the non-condensable gas emitted at the outlet of the reactor (1). e .

3. The method according to claim 2, characterized in that, After the non-condensable gas is discharged into a condensation device or a dehydration device, the flow rate of the non-condensable gas discharged at the outlet of the reactor (1) is measured.

4. The method according to any one of claims 2 to 3, characterized in that... - The temperature inside the reactor (1) is adjusted by controlling the temperature of the heat transfer fluid, and / or - The residence time in the reactor (1) is adjusted by controlling the flow rate of the incoming biomass.

5. The method according to claim 1, characterized in that, The method is carried out in batches, and the emission gas yield is determined by measuring the pressure in the reactor (1) at the end of the carbonization and cooling cycles at a fixed target temperature.

6. The method according to claim 5, characterized in that, The residence time in the reactor (1) is adjusted by controlling the reaction time.

7. The method according to claim 5 or 6, characterized in that, The temperature inside the reactor (1) is regulated by cooling the sealed reactor (1) through the heat exchange fluid passing through the walls of the reactor (1) or the coil.

8. The method according to claim 1 or 2, characterized in that, The amount of reagent injected is adjusted according to the determined emission gas yield, i.e., increased and / or decreased.

9. A method for dewatering biomass, comprising a hydrothermal carbonization method of biomass according to any one of claims 1 to 8 resulting in carbonized sludge, and a mechanical dewatering step of the carbonized sludge.

10. A hydrothermal carbonization device for biomass containing organic matter, comprising: The apparatus comprises a reactor (1), means (11) for feeding the biomass into the reactor (1), means (12) for injecting a heat transfer fluid into the reactor (1), means for injecting a reagent into the reactor (1), and means for circulating a mixture of the biomass, the heat transfer fluid, and the reagent in the reactor (1) under specific pressure and temperature conditions that allow for the conversion of organic matter, characterized in that the apparatus includes means for determining the emission gas yield T of the reactor (1). e The apparatus for determining the emission gas yield T e With the set gas yield T c A device for comparison, and a device for controlling and manipulating the equipment that allows adjustment of at least one of the reaction control parameters within the reactor (1) for adjusting the emission gas yield T. e So that the emission gas yield T e The value tends to be equal to the value of the set gas yield, and the reaction control parameters are the temperature inside the reactor (1), the amount of reagent injected into the reactor (1), and the residence time in the reactor (1).

11. The device according to claim 10, characterized in that, It is suitable for operating a continuous method, the equipment including a gas outlet device for emissions in the reactor (1), and the means for determining the emission gas yield including a means for measuring the emission gas flow rate D. e The device.

12. The device according to claim 11, characterized in that, The method for measuring the emission gas flow rate D e The device is a flow meter at the outlet of the reactor (1).

13. The device according to claim 11, characterized in that, In a continuous method for measuring the emission gas flow rate D e Upstream of the device, there is a condensation or dehydration device.

14. The device according to claim 10, characterized in that, It is suitable for running a batch method, wherein the method for determining the emission gas yield T is used. e The apparatus includes a device for measuring the pressure in the reactor at the end of the cycle.

15. The device according to claim 10, characterized in that, It includes a cooling device that is in indirect contact with a heat transfer fluid in a reactor used in a batch process.

16. The device according to any one of claims 10 to 14, characterized in that, The equipment includes a press downstream of the reactor (1), the press having at least one biomass inlet and a biomass outlet, the biomass inlet of the press being in fluid communication with the carbonized sludge outlet of the reactor (1).

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