Method for treating a liquid carbonaceous feedstock resulting from a hydrothermal liquefaction treatment

Abstract

The invention relates to a method for treating a feedstock resulting from a hydrothermal liquefaction treatment with a view to reducing the content of mineral compounds, the method comprising the following steps: - step a) of diluting the biocrude feedstock with a diluent (8, 12) which comprises an organic liquid phase so as to obtain a diluted biocrude feedstock (9); - step b) of bringing the diluted feedstock (9) obtained in step a) into contact with two separate solvents, which are brought into contact with the feedstock in separate contacting zones (3; 7) and comprise a first solvent (3) which is an aqueous liquid phase having a neutral pH and a second solvent (10) which is an acidic aqueous liquid phase, using counter-current liquid-liquid extraction so as to obtain a raffinate (5) comprising the feedstock depleted in mineral compounds and the diluent and an extract (4) comprising the solvents enriched in mineral compounds; - step c) of separating the raffinate (5) obtained in step b) so as to obtain a biocrude feedstock depleted in mineral compounds (11) and a phase comprising the diluent (8, 12).

Description

[0001] METHOD FOR TREATING A CARBONACEOUS LIQUID FEED FROM A HYDROTHERMAL LIQUEFACTION TREATMENT

[0002] Technical Field

[0003] The present invention relates to the production of recoverable chemical products or biofuels from biomass, in particular lignocellulosic biomass. More specifically, the invention concerns biomass hydrothermal liquefaction processes, also known by the acronym HTL according to their Anglo-Saxon name "HydroThermal Liquefaction", which make it possible to transform biomass into a carbonaceous feedstock known as "biocrude". This feedstock known as "biocrude" must then be treated, in particular by hydroconversion, hydrotreatment, hydrocracking, catalytic cracking, to obtain the desired chemical products with the desired specifications.

[0004] Prior art

[0005] Hydrothermal liquefaction (for more details, please refer to the publication “Continuous Hydrothermal Liquefaction of biomass: a critical review”, D. Castello, TH Pederson, LA Rosendahl, Energies 2018, 11, 3165) is a process for converting a feedstock in the presence of water at a pressure between 100 and 350 bar (between 10 7 Pa and 3.5. 10 7 Pa) and at a temperature between 250 and 450°C. Catalysts can be used for hydrothermal liquefaction: pH modifier, NaOH, KOH, K2CO3, Na2CC>3, etc.

[0006] The products of hydrothermal liquefaction are called "biocrude," consisting mainly of organic molecules, an aqueous phase comprising water-soluble organic compounds (alcohols, acids, ketones, phenols, etc.) and salts, gas, and possibly biochar. Biochar is a solid product rich in carbon, "char" coming from the English word "charcoal." The gas produced is mainly CO2 but can also contain hydrogen, methane, and CO.

[0007] In the hydrothermal liquefaction process, water can be present as a liquid or in a relatively dense supercritical state. Water near the critical point (374°C, 221 bar) has very different properties from water at room temperature. These near-critical properties allow water to play several roles in the conversion process, such as being a reactant, a catalyst, or a source of hydrogen. Near the critical point or in the supercritical state, water has properties that facilitate liquefaction, such as a low dielectric constant that allows solubilization of nonpolar molecules and a sufficiently high ionic product to favor ionic reactions leading to liquid products over free-radical reactions leading to solid or gaseous products.

[0008] The reactions occurring in the hydrothermal liquefaction process are numerous and complex, but include depolymerization reactions including hydrolysis, dehydration, decarboxylation, and repolymerization reactions including condensation.

[0009] The yields and composition of the biocrude depend on the operating conditions, but also on the feedstock treated by hydrothermal liquefaction. For example, for a feedstock consisting of wood, a mass yield of biocrude of around 40-45% and gas yield of 40-45% are obtained by hydrothermal liquefaction.

[0010] The feedstock for hydrothermal liquefaction may be biomass, preferably selected from plants, grasses, trees, wood chips, seeds, fibers, seed coats, aquatic plants, algae, hay and other sources of lignocellulosic materials, such as, for example, those from organic waste, municipal waste, agro-food waste, animal waste, forestry waste, sawmill waste, slaughter residues, agricultural and industrial waste (such as, for example, sugarcane bagasse, waste from oil palm cultivation, sawdust or straw). The feedstock for hydrothermal liquefaction may also come from pulp and paper by-products, whether recycled or not, or from by-products from paper mills, waste such as used plastics, used tires. The feedstock may also be a mixture of at least two of these materials.

[0011] Biocrude obtained by hydrothermal liquefaction is a complex mixture of compounds, consisting mainly of hydrocarbons and oxygenated compounds. In general, the oxygenated compounds are organic acids, ketones, oxygenated aromatic compounds, alcohols, aldehydes, esters, ethers and water. Water generally represents less than 15% by weight of the biocrude. In the case of a lignocellulosic biomass feedstock, the biocrude contains compounds derived from cellulose, hemicellulose and lignin (a structure present in lignocellulosic biomass).

[0012] The biocrude obtained by hydrothermal liquefaction has an oxygen, sulfur and nitrogen content that varies greatly depending on the hydrothermal liquefaction load (algae, wood, etc.). For example, biocrude from hydrothermal liquefaction of wood generally consists of 5 to 20% by weight of oxygen, less than 0.5% by weight of sulfur and less than 5% by weight of nitrogen in the dry biocrude (without water).

[0013] Biocrude can contain up to 4% by weight of inorganic (mineral) compounds, mainly metals such as sodium, potassium but also calcium, iron, etc. These mineral compounds can come from the catalysts used for hydrothermal liquefaction, from the hydrothermal liquefaction feedstock itself, and from metals possibly used to grind the hydrothermal liquefaction feedstock. Sodium and potassium can be present in relatively large quantities in biocrude, as the hydrothermal liquefaction process generally uses alkali-based catalysts (NaOH, KOH, K2CO3, Na2CO3...) in significant quantities.

[0014] This content of inorganics, especially metals, generally does not allow the use of biocrude as fuel because the quantity of ash is too high.

[0015] To be transformed into biofuels (gasoline, kerosene, diesel, marine fuel) or into chemical products, the biocrude must be treated, in particular to reduce the heteroatoms and more particularly the oxygen it contains. This treatment may include at least one operation chosen from hydroconversion, hydrotreatment, hydrocracking, or catalytic cracking. However, these operations use catalysts known to those skilled in the art to be sensitive to metal content (in particular alkali or alkaline-earth metals such as Na, K, Ca, etc.). These metals in fact poison the catalysts: they deactivate them at least partially.

[0016] It is therefore necessary to purify the biocrude, that is to say to reduce its content of mineral compounds, particularly metallic ones, so that its subsequent treatments can be carried out successfully.

[0017] Patent applications WO18177877, WO19092173, WO21121662 disclose treatments aimed at purifying biocrudes, and in particular at recovering the metal salts they contain for recycling, with different types of separation devices, using acidic aqueous phases or even washing agents, but the implementation and implementation of these separation / treatment operations appear complex.

[0018] The invention therefore aims to develop a treatment to reduce the content of mineral compounds, particularly metallic ones, in a biocrude type load, a treatment which is preferably simple to implement, and preferably economical in terms of tools and / or utility consumption.

[0019] Summary of the invention

[0020] The invention firstly relates to a method for treating a liquid feed which comprises at least partly carbonaceous products and which is obtained from a hydrothermal liquefaction treatment, called biocrude feed, with a view to reducing the content of mineral compounds, in particular metallic compounds, such that said treatment comprises

[0021] - a step a) of diluting the biocrude load with a diluent which comprises an organic liquid phase which has a viscosity and a density lower than those of the biocrude load, so as to obtain a diluted biocrude load,

[0022] - a step b) of contacting the diluted biocrude feed obtained in step a) with at least two separate solvents which are brought into contact with said feed in separate contacting zones and comprising a first solvent which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5 and a second solvent which is an acidic aqueous liquid phase, having a pH lower than 6.5, with counter-current liquid-liquid extraction, so as to obtain, on the one hand, a raffinate comprising the biocrude feed depleted in mineral compounds and diluent, and, on the other hand, an extract comprising the solvents enriched in mineral compounds,

[0023] - a step c) of separation of the raffinate obtained in step b), so as to obtain, on the one hand, the biocrude feedstock depleted in mineral compounds, and, on the other hand, a phase comprising the diluent.

[0024] Thus, the invention succeeds in significantly reducing the content of mineral compounds in a biocrude type feedstock, the reduction being sufficient to allow subsequent treatment steps of such a feedstock to be carried out without having to modify its conventional operation, in particular by retaining the type of catalyst usually used for these hydroconversion, hydrotreatment, hydrocracking or catalytic cracking type steps.

[0025] And to do this, the invention first uses a dilution with a "light" organic diluent (less dense and less viscous than the biocrude), then a countercurrent liquid / liquid extraction with two different solvents, which are brought into contact with the diluted biocrude in different zones. An embodiment that will be described later consists of using a liquid / liquid extraction column (or several in series and / or in parallel), in particular a gravity-type column, by differentiating the injection points of the different solvents, at different column heights in particular. And it has proven that this combination of dilution + extraction with two different solvents with differentiated contacting is very effective.

[0026] Carrying out an extraction in such a liquid / liquid extraction column requires a sufficient difference in density between the phases present, here between the diluted biocrude on the one hand, and the two solvents on the other (difference often greater than 50 kg / m 3 ), and the greater the difference in density, the easier this implementation is. Furthermore, the viscosity of one or both phases plays an important role in this operation, because the more it increases, the more the transfer of material between phases will be slowed down on the one hand, and the more the capacity of the column is likely to decrease, in terms of possible charge flow rate per unit of column section, on the other hand.

[0027] Countercurrent columns are interesting because they allow the desired solutes to be extracted much better than in a co-current column or in a stirred tank. Indeed, the number of theoretical stages can reach high values ​​(between 2 and 15 in the vast majority of cases), and with minimized solvent consumption. Using two injection-contact points / two different solvents has surprisingly proven to be very interesting by greatly improving the extraction efficiency.

[0028] Preferably, the first solvent S1 is chosen from pure water, demineralized water, water with soluble organic molecules.

[0029] Preferably, the second solvent S2 is an acidic aqueous solution, having a pH less than 6.5.

[0030] Advantageously, the second solvent S2 is an acidic aqueous solution containing from 10 ppm (in particular 100 ppm), to 20% by weight of at least one strong or weak acid, organic or mineral, in particular chosen from at least one of the following acids: acetic acid, nitric acid, sulfuric acid, hydrochloric acid, citric acid, oxalic acid, lactic acid, formic acid, and possibly soluble organic molecules.

[0031] The second solvent may also be an aqueous solution acidified by injecting carbon dioxide into the aqueous solution (which may already contain at least one acid among those mentioned above). Indeed, the hydrothermal liquefaction step prior to the treatment according to the invention tends to generate carbon dioxide, which can therefore be advantageously used to acidify the solvent in question. In step b) of contacting, the ratio Ri of the flow rate of the first solvent Q si on the flow rate of the diluted biocrude load Q mis preferably between 0.05 and 5, preferably between 0.1 and 3.

[0032] In contacting step b), the ratio R2 of the flow rate of the second solvent CU2 to the flow rate of the diluted biocrude load Q m is preferably between 0.05 and 5, preferably between 0.1 and 3.

[0033] Preferably, contacting step b) comprises dedicated or additional decantation to improve decantation between the two aqueous and organic phases. The decantation device used (e.g., a decanter) may be located after the column or the last liquid-liquid extraction column when there are several, or between two liquid-liquid extraction columns in series that are used in separation step c). The extraction column (or one of those used in step c) may have a short residence time decantation function, which tends to separate the phases in a non-optimal manner, and it is possible that a residual free water fraction (drops) is entrained in the raffinate 25. In this case, a decanter may be placed downstream on the line to better separate the water (and not upstream of the column).If the contact between the two liquid phases is done via two separate columns, then a decanter can be placed between the two columns, or just one at the outlet of the second column (or no decanter).

[0034] The method according to the invention may also comprise:

[0035] - a step d) of recycling at least part of the phase comprising the diluent obtained in step c) as diluent in step a) of dilution.

[0036] This recycling can be partial or total: it can be supplemented by the addition of external diluent if necessary, but it is very interesting, because it allows the consumption of diluent in the process to be drastically reduced.

[0037] Advantageously, the method of the invention can also comprise:

[0038] - a step e) of treatment of the extract obtained in step b) of contacting to reduce its content of mineral compounds,

[0039] - a step f) of recycling at least part of the extract with reduced content of mineral compounds obtained in step e) as a solvent in step b) of contacting.

[0040] Here again, it is therefore possible to recycle at least partially this extract, preferably by purifying it beforehand, to replace all or part of at least one of the (aqueous) solvents used during the liquid / liquid extraction, which also makes it possible to reduce the water consumption of the process of the invention. Step e) can also make it possible to recover these mineral compounds, for example metal salts, with a view to recycling them.

[0041] Preferably, during dilution step a), the diluent has a final boiling point of at most 150°C, preferably at most 100°C.

[0042] Preferably, the diluent used in dilution step a) is chosen from a light cut present in the feedstock or a chemical compound or mixture of chemical compounds, in particular from the family of alcohols, ethers, ketones and hydrocarbons.

[0043] Advantageously, the process can be started with a solvent with a boiling temperature close to that of the cut to be recycled, then the light cut will accumulate in the loop over time, because it is recycled (by distillation), and it will gradually replace the initial solvent.

[0044] Preferably, at the end of dilution step a), the diluted biocrude load has a dynamic viscosity at 20°C of at most 7 cP, preferably at most 4 cP, and a density at 15°C of at most 950 kg / m 3 , preferably not more than 900 kg / m 3 .

[0045] Preferably, during dilution step a), the ratio R of the flow rate Qd of the diluent to the flow rate Qb of the biocrude load is at most 10, and in particular at least 0.1, the ratio R preferably being between 0.5 and 3.

[0046] Preferably, contacting step b) is carried out at a temperature between 15°C and 100°C, while remaining below the boiling point of the diluent, and at a pressure between 0.5 10 5 Pa and 5. 10 5 Pa.

[0047] Preferably, separation step c) is a treatment comprising at least one evaporation, one distillation, one heating followed by one separation.

[0048] The invention also relates to an installation for treating a liquid load comprising products at least partly carbon-based and resulting from a hydrothermal liquefaction treatment, called biocrude load, with a view to reducing the content of mineral compounds, in particular metallic compounds, which implements the method described above.

[0049] The invention also relates to an installation for treating a liquid load comprising at least partly carbonaceous products and resulting from a hydrothermal liquefaction treatment, called biocrude load, with a view to reducing the content of mineral compounds, in particular metallic compounds, such that said installation comprises

[0050] - a device a) for diluting the biocrude feed with a diluent which comprises an organic phase which has a viscosity and a density lower than those of the biocrude feed, so as to obtain a diluted biocrude feed - a device b) for contacting the diluted biocrude feed obtained in step a) with at least two separate solvents, including a first solvent which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5 and a second solvent which is an acidic aqueous liquid phase, having a pH lower than 6.5, said device comprising a countercurrent liquid-liquid extraction column, preferably gravity-fed, the first and second solvents having separate inlets and arranged at different heights of the column, so as to obtain, on the one hand, a raffinate comprising the biocrude feed depleted in mineral compounds and diluent, and, on the other hand, an extract comprising the solvents enriched in mineral compounds

[0051] - a device c) for separating the raffinate obtained with the contacting device b), so as to obtain, on the one hand, the biocrude load depleted in mineral compounds, and on the other hand a phase comprising the diluent.

[0052] The installation according to the invention therefore combines a dilution device with a “light” organic diluent (less dense and less viscous than the biocrude), and one (at least) countercurrent liquid / liquid extraction column with two different solvents, at different injection points. Preferably, at least one of the solvents is injected at the top of the column while the other solvent is injected at an intermediate height of the column, and the diluted biocrude is injected in the lower part of the column, in particular at the bottom of the column.

[0053] According to a variant, at least one of the first and second solvents comprises at least two separate inlets arranged at different heights of the column. Thus, one of the solvents may have two different injection points, at different column heights, for example an injection point at the top of the column and (at least) another at an intermediate column height, or two injection points at different intermediate column heights.

[0054] For example, at least one of the inlets for the first solvent may be at the top of the column. It is also possible that one of the inlets for the second solvent may be at the top of the column.

[0055] For example, at least one of the inlets of the second solvent is at an intermediate height of the column, in particular at a height H2 relative to the total height H of the column such that the ratio H2 / H is between 0.2 and 0.8.

[0056] It is also possible that it is rather one of the inlets of the first solvent which is at an intermediate height of the column, in particular at the H2 height in question.

[0057] The total height H is understood to mean the useful height of the column, as is known in the field of liquid-liquid extraction or distillation columns. If the first solvent (or the second solvent) has a second inlet into the column at an intermediate height H3, then this intermediate height H3 is preferably lower than the height H2 of the inlet of the second solvent (or first solvent).

[0058] Advantageously, this height H3 of the second inlet of the first solvent (or of the second solvent) can be such that, H being the total height of the column, the ratio H3 / H is between 0.05 and 0.4.

[0059] The contacting device is preferably a gravity-fed countercurrent liquid / liquid extraction column. It may be a single column or a plurality of columns, connected in series or in parallel. The column(s) may be equipped at the top and / or bottom of the column with settling devices.

[0060] The dilution device may be a tank-type device fed by both the biocrude feed and the diluent. It may also simply be implemented by a plurality of supply lines that converge to a common line(s) where mixing / dilution is carried out dynamically up to the contacting device, using appropriate valves.

[0061] The separation device is, for example, at least one device chosen from: a distillation column, an evaporator, an exchanger followed by a separator flask, in particular a so-called “flash” separator flask.

[0062] The installation according to the invention may also comprise a device for recycling at least part of the phase comprising the diluent obtained with the separation device c) as a diluent for the dilution device a). This recycling device may consist of pipe(s) providing a fluid connection between the two devices a) and c) and controlled in a known manner by valves.

[0063] The invention also relates to a method for treating biomass comprising hydrothermal liquefaction of biomass, then a treatment aimed at reducing the content of mineral compounds in the biocrude obtained, as described above, then, preferably, a conversion treatment of the treated biocrude of the hydroconversion, hydrotreatment, hydrocracking, catalytic cracking type in order to produce biofuels and / or other chemical compounds (called biosourced).

[0064] List of Figures

[0065] Figure 1: This figure very schematically represents an installation implementing the biocrude treatment method according to the invention. Figure 2: This figure very schematically represents a variant of the installation implementing the biocrude treatment method according to the invention shown in Figure 1.

[0066] These figures therefore do not represent all the equipment in the installation, but those which are most useful for understanding the invention. The various devices and others are not necessarily to scale, nor necessarily represented in space as they might be in an industrial site.

[0067] The same references refer to the same devices, to the same flows from one figure to another.

[0068] Description of the embodiments

[0069] The invention aims to treat biocrude-type loads in order to reduce their content of mineral compounds, particularly metallic ones.

[0070] As a reminder, the characteristics of a biocrude-type feedstock of interest to the invention may be as follows: The biocrude obtained by hydrothermal liquefaction is a complex mixture of compounds consisting mainly of hydrocarbons and oxygenated compounds. In general, the oxygenated compounds are organic acids, ketones, oxygenated aromatic compounds, alcohols, aldehydes, esters, ethers and water. Water generally represents less than 15% by weight of the biocrude.

[0071] In the case of a lignocellulosic biomass feedstock, the biocrude contains compounds derived from cellulose, hemicellulose and lignin (structure present in lignocellulosic biomass).

[0072] The biocrude obtained by hydrothermal liquefaction has an oxygen, sulfur and nitrogen content that varies greatly depending on the hydrothermal liquefaction load (algae, wood, etc.). For example, biocrude from hydrothermal liquefaction of wood generally consists of 5 to 20% by weight of oxygen, less than 0.5% by weight of sulfur and less than 5% by weight of nitrogen in the dry biocrude (without water).

[0073] Biocrude can contain up to 4% by weight of inorganics, mainly metals such as sodium, potassium but also calcium, iron, etc. Inorganics can come from the catalysts used for hydrothermal liquefaction, the hydrothermal liquefaction feedstock, and the metals used to grind the hydrothermal liquefaction feedstock. Sodium and potassium can be present in significant quantities in biocrude because the hydrothermal liquefaction process uses alkali-based catalysts (NaOH, KOH, K2CO3, Na2CO3, etc.) in significant quantities.

[0074] Biocrude is generally characterized by a kinematic viscosity at 50°C between 10 and 40,000 cSt, a dynamic viscosity at 50°C between 10 and 40,000 cP, a density at 15°C between 0.9 and 1.2 and a final distillation temperature exceeding 750°C.

[0075] Biocrude has a very wide distillation range, from room temperature to over 750°C. For example, for biocrude from hydrothermal liquefaction of wood, approximately 10% by weight of the biocrude is vaporized in the range 20-180°C, 10% by weight to 45% by weight of the biocrude is vaporized in the range 180-350°C, and 45% by weight to 80% by weight of the biocrude is vaporized above 350°C.

[0076] Figure 1 shows an installation for implementing the invention which will be described below.

[0077] Biocrude 1 from the hydrothermal liquefaction unit has a flow rate Qb. Biocrude 1 is mixed with diluent 8 having a flow rate Qd such that 0.1 < Qd / Qb < 10 and preferably such that 0.5 < Qd / Qb < 3. The flow rates are in mass per unit of time. Diluent 8 is a compound or a mixture of compounds having a dynamic viscosity at 20°C of less than 4 cP and a density at 15°C of between 600 and 850 kg / m 3Dilution is carried out by providing in the biocrude 1 supply line to the extraction column 2 a tapping of a pipe bringing the diluent: the mixing between the biocrude and the diluent is carried out in the common pipe section downstream of the tapping. (“upstream” and “downstream” are understood in this text by taking into account the progression of the biocrude load in the installation).

[0078] Mixture 9, biocrude + diluent, called “diluted biocrude”, here has a dynamic viscosity at 20°C less than or equal to 7 cP, preferably less than or equal to 4 cP and a density at 15°C less than or equal to 950 kg / m 3 , preferably less than or equal to 900 kg / m 3 at atmospheric pressure (and for example at least 600 kg / m 3 at atmospheric pressure). These properties are obtained by choosing an adequate diluent type and diluent flow rate (relative to the biocrude flow rate).

[0079] The diluent 12 may be a light fraction present in the biocrude, accumulated in the recycling loop over time (as seen further with Figure 2), or be a chemical compound (or a mixture of chemical compounds) present or not in the biocrude. The diluent may consist, for example, of compounds from the family of alcohols, ethers, ketones and hydrocarbons. The final boiling point of the diluent 12 is preferably less than or equal to 150°C, and preferably less than or equal to 100°C, and more preferably at least 60°C.

[0080] The diluted biocrude 9 feeds a liquid-liquid extraction column called gravity 2 at its foot with a given mass flow rate Qm. Column 2 extends along a vertical or essentially vertical longitudinal axis.

[0081] Liquid-liquid extraction is carried out according to the invention using two different solvents S1 and S2, injected at different injection points in column 2: (the invention can also be carried out with more than two different solvents):

[0082] Solvent S1 consists of an aqueous solution at neutral pH (6.5 < pH < 7.5), which can be pure water, demineralized water, water with soluble organic molecules. Solvent S2 consists of an acidic aqueous solution containing 10 ppm and 20% by weight of an acid such as acetic acid, nitric acid, sulfuric acid, hydrochloric acid, citric acid, oxalic acid, lactic acid, formic acid or any other acid. Solvent S2 can also contain soluble organic molecules.

[0083] Solvent S1 feeds column 2 via stream 3, at the top of the column. The flow rate Qs1 of stream 3 is chosen such that 0.05 < Qs1 / Qm < 5 and preferably 0.05 < Qs1 / Qm < 3.

[0084] Solvent S2 feeds column 2 via stream 7, in an intermediate position in column 2.

[0085] The flow rate Qs2 of stream 7 is chosen such that 0.05 < Qs2 / Qm < 5 and preferably 0.05 < Qs2 / Qm < 3.

[0086] The flow rates are expressed in mass per unit time. It is also possible to reverse the injection points, and inject solvent S2 through stream 3 and solvent S1 through stream 7.

[0087] The total useful height of column 2, H, is between 1.5 m and 50 m high, preferably between 1.8 m and 25 m. The column can be of different types: packed column, perforated tray column, mechanically stirred column, pulsed column or other.

[0088] With H2 the height between the column foot (in its useful part) and the position of the injection point of stream 10, the ratio H2 / H is between 0.2 and 0.8. According to a first variant (therefore optional) of the invention, and as shown in Figure 1, the solvent S1 is injected partly at the top of the column via stream 3, but also partly in the lower position, via stream 6, with flow rate Qs1'.

[0089] With H3 the height between the column foot (in its useful part) and the position of the injection point of current 6, the ratio H3 / H is between 0.05 and 0.4, and H3 remains lower than H2. (injection point 6 is located lower than injection point 10) QsT is chosen such that 0.05 < QsT / Qm < 5, and preferably 0.05 < Qs17Qm < 3.

[0090] Liquid-liquid extraction column 2 has the following characteristics:

[0091] - Operating pressure P between 0.5 bar abs (0.5.105 Pa) and 15 bar abs (15.10 5 Pa), preferably between 0.9 bar abs (0.9.10 5 Pa) and 1.5 bar abs (1.5.10 5 Pa).

[0092] - Operating temperature T between 15°C and 150°C, preferably between 20°C and 60°C

[0093] - F / S between 5 and 80 m / h, preferably between 10 and 40 m / h with:

[0094] S the passage section of column 2, in m 2

[0095] F the total volume traffic in column 2, F being defined as follows

[0096] F = Qm / rhom + (Qs1 + Qs1') / rhos1 + Qs2 / rhos2, expressed in m 3 / h rhom, rhosl and rhos2 being the respective densities of the diluted biocrude 9, the solvent S1 and the solvent S2 under the operating conditions of column 2 (pressure, temperature)

[0097] In column 2, two phases are mixed and brought into contact: an organic phase (diluted biocrude 9) and an aqueous phase (solvent S1 and solvent S2). In column 2, one phase is dispersed in the other, which is the continuous phase.

[0098] The organic phase is called the light phase because its density is lower than the other phase, the aqueous phase. The aqueous phase is called the heavy phase.

[0099] The dispersed phase can be the heavy phase (solvent 3, solvent 7) or the light phase (diluted biocrude 9), but preferably the light phase (diluted biocrude 9). If the dispersed phase is the heavy phase (solvent 3, solvent 7), column 2 is preferably equipped with a decanter at its bottom. The decanter will be at the top of the column if the dispersed phase is the light phase (diluted biocrude 9). A decanter can also be provided at the bottom and top of the column. The column allows a theoretical number of stages to be reached between 2 and 15, and preferably between 2.5 and 7.

[0100] The effluents from column 2 are:

[0101] - A raffinate 5 consisting mainly of biocrude, diluent and compounds present in the solvents (mainly water). The quantity of inorganics present in raffinate 5 is much lower than that in diluted biocrude 9, due to the efficiency of liquid-liquid extraction.

[0102] - An extract 4 consisting mainly of solvents S1 and S2, extracted inorganics, compounds present in the diluted biocrude 9, such as diluent and biocrude.

[0103] The raffinate 5 feeds a separation device 10 based on the boiling temperature, such as a distillation column, an evaporator, an exchanger followed by a flash separator drum. This device makes it possible to separate a “diluent” 8 which is made up of a light constituent or a mixture of light constituents, and a demineralized biocrude 11 having a greatly reduced content of inorganics, in particular metals, compared to the biocrude 1.

[0104] This allows us to reduce at least 70% of the mineral compound content in the biocrude, in particular to achieve a maximum mineral compound content (their sum) of at most 500 ppm, in particular at most 400 or 300 or 200 or 100 ppm, which is remarkable.

[0105] Figure 2 shows a variant of the installation of Figure 1: the difference with the installation of Figure 1 is that at least part of phase 8 comprising the diluent from contacting step b) is recycled as diluent in dilution step a). This allows the diluent consumption of the installation to be greatly reduced.

[0106] According to a third variant of the process according to the invention (possibly combined with at least one of the first and second variants), not shown in the figures, one of the two solvents, in particular solvent S1 or solvent S2 (stream 3 and possibly stream 6 and / or 10) can come from the recycling of extract 4, if extract 4 has previously undergone treatment to reduce its inorganic content (by evaporation for example). It is thus also possible to greatly reduce the water consumption of the process.

[0107] It should be noted that in the recycling of any stream envisaged within the framework of the present invention, the stream may only be partially recycled, and the recycled stream may be supplemented by a stream of similar external composition (for example an addition of water in the recycling of extract 4 as a solvent or an addition of organic phase in the recycling of stream 8 as a diluent).

[0108] Examples

[0109] Comparative example 1 (state of the art)

[0110] A biocrude from hydrothermal liquefaction of lignocellulosic biomass has a dynamic viscosity at 20°C of 142 cP and a density at 15°C of 985 kg / m 3 . The biocrude contains several inorganic compounds, also called mineral compounds, including sodium Na, potassium K and calcium Ca. The sodium concentration is 912 ppm by weight, that of potassium is 640 ppm by weight and that of calcium is 30 ppm by weight.

[0111] The biocrude is diluted with 2-butanone (or methyl ethyl ketone, or MEK) with a MEK / biocrude mass ratio of 1 to reduce the density and viscosity. MEK has a density at 15°C of 805 kg / m 3 and a dynamic viscosity at 20°C of 0.42 cP. MEK has a boiling point of 79.6 °C.

[0112] The diluted biocrude has a dynamic viscosity at 20°C of 1.7 cP and a density at 15°C of 890 kg / m 3 .

[0113] A contact test of the diluted biocrude with acidic water is carried out in a closed 3-liter reactor with a water / diluted biocrude mass ratio equal to 0.5. The acidic water contains 0.1M citric acid. The reactor, equipped with mechanical stirring means (a propeller), is stirred at 500 rpm for 1 hour and then left to stand for 1 day. The reactor is operated at 40°C under 1 atm (10 5 Pa).

[0114] The decanted organic phase is separated and then distilled to separate the diluent from the demineralized biocrude. The analytical results of the demineralized biocrude indicate a sodium content of 33 ppm by weight, a potassium content of 21 ppm and a calcium content of 10 ppm in the demineralized biocrude.

[0115] Example 2 according to the invention

[0116] The same diluted biocrude as in Example 1 is used to feed a Sulzer ECR type stirred countercurrent liquid-liquid extraction column, with an internal diameter of 32 mm and a useful height of 1800 mm.

[0117] The operation is carried out at 40°C under 1 atm (10 5 Pa). The column is stirred at a stirring speed of 90 rpm during the operation.

[0118] The dispersed phase is the light phase (diluted biocrude). The diluted biocrude has a flow rate of 6 kg / h and feeds the column at its bottom. Demineralized water is used as solvent S1, and feeds the column at its top (stream 3) with a flow rate of 0.5 kg / h.

[0119] A 0.1M citric acid solution is used as solvent S2, and feeds the column (stream 10) with a flow rate of 2.5 kg / h, at an injection point located in the middle of column 2 (900 mm height).

[0120] Column 2 has an estimated number of theoretical stages of around 3 under the conditions of use presented.

[0121] The organic phase thus treated and exiting at the top of extraction column 2 is distilled to separate the diluent from the demineralized biocrude. The analysis results of the demineralized biocrude indicate a sodium content of 3 ppm by weight, a potassium content of 1 ppm and a calcium content of 7 ppm in the demineralized biocrude.

[0122] The sodium, potassium and calcium contents obtained with these two examples are compiled in Table 1 below:

[0123] Table 1

[0124] From the comparison of these two examples, we see that with the process of the invention using a particular liquid-liquid extraction with two different aqueous solvents in counter-current is much more effective than a simple contacting in a stirred reactor: with the invention it is possible to dramatically reduce the sodium content of the biocrude from 912 ppm to 3 ppm, that is to say that it is possible to practically eliminate all the sodium. And this is also the case for potassium, and calcium to a lesser extent.

Claims

Claims 1. Method for treating a liquid feed which comprises at least partly carbonaceous products and which comes from a hydrothermal liquefaction treatment, called biocrude feed (1), with a view to reducing the content of mineral compounds, in particular metallic compounds, characterized in that said treatment comprises - a step a) of diluting the biocrude load with a diluent (8,12) which comprises an organic liquid phase which has a viscosity and a density lower than those of the biocrude load, so as to obtain a diluted biocrude load (9), - a step b) of contacting the diluted biocrude feed (9) obtained in step a) of dilution with at least two separate solvents which are brought into contact with said feed in separate contacting zones (3; 7) and comprising a first solvent (3) which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5 and a second solvent (10) which is an acidic aqueous liquid phase, having a pH lower than 6.5, with counter-current liquid-liquid extraction, so as to obtain, on the one hand, a raffinate (5) comprising the biocrude feed depleted in mineral compounds and diluent, and, on the other hand, an extract (4) comprising the solvents enriched in mineral compounds, - a step c) of separation of the raffinate (5) obtained in step b) of contacting, so as to obtain, on the one hand, the biocrude charge depleted in mineral compounds (11), and, on the other hand, a phase comprising the diluent (8,12).

2. Method according to the preceding claim, characterized in that the first solvent (3) is chosen from pure water, demineralized water, water with soluble organic molecules.

3. Method according to one of the preceding claims, characterized in that the second solvent (7) is an acidic aqueous solution having a pH less than 6.5 4. Method according to one of the preceding claims, characterized in that the second solvent (7) is an acidic aqueous solution containing from 10 ppm to 20% by weight of at least one strong or weak acid, organic or mineral, in particular chosen from at least one of the following acids: acetic acid, nitric acid, sulfuric acid, hydrochloric acid, citric acid, oxalic acid, lactic acid, formic acid, and possibly soluble organic molecules.

5. Method according to one of the preceding claims, characterized in that, in step b) of contacting, the ratio Ri of the flow rate of the first solvent Q si on the flow rate of the diluted biocrude load Q m is between 0.05 and 5, preferably between 0.1 and 3.

6. Method according to one of the preceding claims, characterized in that, in step b) of contacting, the ratio R2 of the flow rate of the second solvent CU2 to the flow rate of the diluted biocrude load (9) Q m is between 0.05 and 5, preferably between 0.1 and 3.

7. Method according to the preceding claim, characterized in that it comprises - a step d) of recycling at least a part (8) of the phase comprising the diluent as diluent in step a) of dilution.

8. Method according to one of the preceding claims, characterized in that it comprises - a step e) of treatment of the extract (4) obtained in step b) of contacting to reduce its content of mineral compounds, - a step f) of recycling at least part of the extract (4) with reduced content of mineral compounds obtained in step e) of treatment / as solvent (3) in step b) of contacting.

9. Method according to one of the preceding claims, characterized in that, during the dilution step a), the diluent (8, 12) has a final boiling temperature of at most 150°C, preferably at most 100°C.

10. Method according to one of the preceding claims, characterized in that, at the end of dilution step a), the diluted biocrude charge (9) has a dynamic viscosity at 20°C of at most 7 cP, preferably at most 4 cP, and a density at 15°C of at most 950 kg / m 3 , preferably not more than 900 kg / m 3 .

11. Method according to one of the preceding claims, characterized in that, during the dilution step a), the ratio R of the flow rate Qd of the diluent (8, 12) to the flow rate Qb of the biocrude load (1) is at most 10, and in particular at least 0.1, the ratio R preferably being between 0.5 and 3.

12. Method according to one of the preceding claims, characterized in that step b) of contacting is carried out at a temperature between 15°C and 100°C and at a pressure between 0.5.10 5 Pa and 5.10 5 Pa.

13. Method according to one of the preceding claims, characterized in that step c) of separation is a treatment comprising at least one evaporation, one distillation, one heating followed by one separation.

14. Method according to one of the preceding claims, characterized in that the diluent (8, 12) used in dilution step a) is chosen from a light cut present in the biocrude load or a chemical compound or mixture of chemical compounds, in particular from the family of alcohols, ethers, ketones and hydrocarbons.

15. Installation for treating a liquid load comprising products which are at least partly carbonaceous and which come from a hydrothermal liquefaction treatment, called biocrude load, with a view to reducing the content of mineral compounds, in particular metallic compounds, characterized in that said installation comprises - a device a) for diluting the biocrude load with a diluent (8) which comprises an organic phase which has a viscosity and a density lower than those of the biocrude load (1), so as to obtain a diluted biocrude load (9) - a device b) for contacting (2) the diluted biocrude feed (9) obtained with the device a) for dilution with at least two separate solvents (3; 7) including a first solvent (3) which is an aqueous liquid phase at neutral pH, in particular between 6.5 and 7.5 and a second solvent (7) which is an acidic aqueous liquid phase, having a pH lower than 6.5, said device comprising a column (2) for counter-current liquid-liquid extraction, preferably gravity-fed, the first and second solvents having separate inlets and arranged at different heights of the column, so as to obtain, on the one hand, a raffinate (5) comprising the biocrude feed depleted in mineral compounds and diluent, and, on the other hand, an extract (4) comprising the solvents enriched in mineral compounds - a device c) for separating (10) the raffinate obtained with the contacting device b), so as to obtain on the one hand the biocrude charge depleted in mineral compounds (11), and, on the other hand, a phase comprising the diluent (8).

16. Installation according to the preceding claim, characterized in that at least one of the first and second solvents (3, 7) comprises at least two separate inlets arranged at different heights of the column (2).

17. Installation according to one of claims 15 or 16, characterized in that at least one of the inlets of the first solvent (3) is at the top of the column (2).

18. Installation according to one of claims 15 to 17, characterized in that at least one of the inlets of the second solvent (7) is at an intermediate height H2 of the column (2), in particular at a height H2 relative to the total height H of the column such that the ratio H2 / H is between 0.2 and 0.

8.

19. Installation according to the preceding claim, characterized in that the first solvent has a second inlet (6) in the column at an intermediate height H3 which is lower than the height H2 of the inlet of the second solvent (7).

20. Installation according to the preceding claim, characterized in that the height H3 of the second inlet (6) of the first solvent is such that, H being the total height of the column, the ratio H3 / H is between 0.05 and 0.

4.

21. Installation according to one of claims 15 to 20, characterized in that the separation device (10) comprises at least one device chosen from a distillation column, an evaporator, an exchanger followed by a separator tank, in particular a so-called “flash” separator tank.

22. Installation according to one of claims 15 to 21, characterized in that it comprises a device for recycling at least part of the phase (8) comprising the diluent obtained with the separation device c) as diluent for the dilution device a).

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