Process for treating lignocellulosic biomass

Abstract

The invention relates to a process for treating lignocellulosic biomass, employing at least one reactor (9; 14) for treating said biomass, said reactor (9; 14) being equipped with a feeding device (6; 11) having a biomass inlet and a biomass outlet, said biomass outlet being in fluidic connection with an inlet of the reactor, such that: - a residue (8; 13) is extracted from the biomass as it passes through the feeding device (6; 11) to the reactor (9; 14) via an extraction outlet provided in said device, said residue being a mixture of solid and liquid; - said residue is separated into a solid residue (32; 42) and a liquid residue (31; 41); - at least a portion of the solid residue (32; 42) is reintroduced into the feeding device, or into one of said feeding devices. Figure for the abstract: Fig. 2

Description

Title of the invention: Process for treating lignocellulosic biomass technical field

[0001] The invention relates to a process for treating lignocellulosic biomass to produce so-called second-generation (2G) sugar juices. These sugar juices can be used to produce other products by biochemical means (for example, alcohols such as ethanol, butanol, or other molecules, for example, solvents such as acetone, etc.). This process generally comprises three steps: the preparation of the liquor, the impregnation of the biomass with this liquor, and the pretreatment of the impregnated biomass, for example, by cooking possibly coupled with a steam explosion. Previous technique

[0002] Lignocellulosic biomass represents one of the most abundant renewable resources on Earth. The substrates considered are very varied, including woody substrates such as different types of wood (hardwood and softwood), by-products from agriculture (wheat straw, corn cobs, etc.) or from other agri-food, paper, etc. industries...

[0003] The process for the biochemical transformation of lignocellulosic biomass into 2G sugar juices includes, in particular, a pretreatment step and an enzymatic hydrolysis step using an enzyme cocktail. These processes also most often include an impregnation step prior to pretreatment. The sugar juices resulting from hydrolysis are then processed, for example by fermentation, and the process also includes separation steps and / or a purification step of the final product.

[0004] Lignocellulosic biomass is composed of three main polymers: cellulose (35 to 50% by weight), which is a polysaccharide essentially made up of hexoses; hemicellulose (20 to 30% by weight), which is a polysaccharide essentially made up of pentoses; and lignin (15 to 25% by weight), which is a complex, high molecular weight polymer composed of aromatic alcohols linked by ether bonds. These different molecules are responsible for the intrinsic properties of the plant cell wall and are organized into a complex network.

[0005] Among the three basic polymers that incorporate lignocellulosic biomass, cellulose and hemicellulose are those that allow the production of 2G sugar juices.

[0006] Most often, hemicellulose is mostly broken down into sugar during pretreatment, and cellulose is converted into glucose by enzymatic hydrolysis. However, access to raw cellulose remains difficult for enzymes, hence The need for pretreatment. This pretreatment modifies the physicochemical properties of lignocellulosic biomass to improve the accessibility of cellulose to enzymes and its reactivity to enzymatic hydrolysis.

[0007] Numerous technologies relevant to the invention exist for carrying out this pretreatment, which will hereafter be grouped under the generic term "cooking": acid cooking, alkaline cooking, autohydrolysis cooking, steam explosion, and so-called "organosolv pulping" processes (or organo-solvent treatment in French). This last process involves pretreatment in the presence of one or more organic solvents and generally water. The solvent can be an alcohol (ethanol), an acid such as acetic acid or formic acid, or even acetone. Organosolv pulping processes lead to at least partial solubilization of the lignin and partial solubilization of the hemicelluloses. Two output streams are then produced: the substrate pretreated with residual cellulose, hemicellulose, and lignin, and the solvent phase containing the solubilized lignin and some of the hemicelluloses.There is generally a solvent regeneration step that allows for the extraction of a lignin stream. Some organosolv pulping treatments (particularly those using ethanol) are coupled with the addition of a strong acid (such as H2SO4). It is also possible to consider contacting the biomass with the solvent via an impregnation reactor before the cooking phase, or contacting the biomass with the acid catalyst before performing organosolv pulping.

[0008] Different configurations are reported for example in the document “Production of bioethanol from lignocellulosic materials via the biochemical pathway: A review”, M. Balat, Energy Conversion and Management 52 (2011) 858-875, or in the document “Bioethanol production from agricultural wastes: an overview”, N. Sarkar, S. Kumar Ghosh, S. Bannerjee, K. Aikat, Renewable Energy 37 (2012) 19-27.

[0009] One of the most effective pretreatments is steam blasting, particularly under acidic conditions, which allows for almost complete hydrolysis of hemicellulose and a significant improvement in the accessibility and reactivity of cellulose to enzymes. This pretreatment may be preceded by other treatment(s).

[0010] All these pretreatments are applied to biomasses which are initially in solid form; the purpose of the pretreatment is to destructure them.

[0011] US patents 8057639 and 8512512 describe a process comprising a first step of hydrolyzing hemicellulose into C5 sugars under mild conditions, thus preserving them from degradation. This step is carried out in a first reactor under a pressure of 1.5 bar (0.15 MPa) or more, by steam injection, at a temperature of 110°C or more, and optionally in the presence of a weak acid. After this step, a washing is performed to extract and recover the sugar juices from The hemicellulose (generally C5 and C6 sugars, the relative proportions of which depend, in particular, on the nature of the biomass) is extracted before the remaining biomass, enriched in cellulose and lignin, is sent to a second stage (second reactor) where the steam explosion takes place. This second reactor operates at a higher pressure than the first reactor, with a high-pressure steam injection that causes a sudden expansion of the biomass (steam explosion).

[0012] Whenever a treatment requires a pressure step (impregnation, pretreatment such as cooking, or other), it is necessary to use means of introducing solid biomass that are compatible with these pressure steps. This is the case, for example, with compression screws, one embodiment of which is described in US patent 4,599,138.

[0013] French patent FR 3 075 203 describes a process involving impregnating biomass with an acidic liquor, followed by cooking and steam explosion of the impregnated biomass, with adjustment of the acidity of the acidic liquor and its recycling. French patent FR 3 075 201 also describes a process for pretreating biomass by acid impregnation followed by steam explosion, further involving washing the reactor feed means and recycling the wash water into the process.

[0014] The invention aims to improve the treatment of lignocellulosic biomass. In particular, it aims to improve the introduction of biomass into a reactor operating one or more of the biomass treatment stages.

[0015] Its purpose is more specifically to improve the steam explosion impregnation and / or cooking stages of biomass as described in the aforementioned prior documents. The invention also aims to make the treatment process, and in particular these two stages, more efficient in terms of energy and / or treatment fluid consumption and / or biomass conversion yield.

[0016] Summary of the invention The invention relates firstly to a process for treating lignocellulosic biomass comprising a dry matter content of no more than 90% by weight, said process comprising the use of at least one biomass treatment reactor, said reactor being equipped with a biomass feeding device having a biomass inlet and a biomass outlet, said biomass outlet being in fluidic connection with an inlet of the reactor. This process is characterized by the fact that - that a residue is extracted from the biomass, during its passage through the feeding device to the reactor, via an extraction outlet provided in said device, said residue, called solid-liquid residue, being a mixture of solid and liquid, - by separating the said solid-liquid residue into a solid residue and a liquid residue, - and that at least part of the solid residue is reintroduced into the same feeding device, or into one of said feeding devices in the case of a plurality of reactors.

[0017] In the context of the invention, "lignocellulosic biomass comprising a dry matter content of X%" means either biomass that naturally comprises a dry matter content of X% (so-called native biomass), or biomass that has this content after one or more operations prior to the process according to the invention. This dry matter content (acronym "DM") refers to the dry matter content measured according to ASTM E1756-08(2015) "Standard Test Method for Determination of Total Solids in Biomass".

[0018] In the context of the invention, "solid-liquid residue" means a liquid containing suspended solids (solid particles). "Solid residue" means a residue comprising at least 20% by weight of solids (in particular at least 30% or 40%, or even at least 50% by weight of solids depending on the separation method envisaged) and having a solid consistency such as mud or acid-impregnated biomass fragments. "Liquid residue" means a residue comprising at least 50% by weight of liquid, in particular at least 80% by weight of liquid, and having the consistency of a liquid devoid or substantially devoid of suspended solid particles.

[0019] The invention, as will be detailed later, can advantageously be applied to any type of reactor used in a biomass conversion process, and more particularly to biomass impregnation reactors (when impregnation is provided, whether by a liquor comprising a chemical compound such as an acid, a base or an oxidizing agent or by a water-based liquor, with autolysis of the biomass naturally releasing an acid, in particular acetic acid) and / or to heat treatment reactors of the cooking or steam explosion type.

[0020] The invention consisted of proposing to extract from biomass before its entry into the reactor a residue which is partly solid and partly liquid, and to make optimal use of it.

[0021] In fact, it was already known to extract / recover a liquid (aqueous) residue / liquid wash water from the means of feeding the reactors in question, to adjust the dry matter content of the biomass, to wash the equipment which allows feeding the reactor with biomass, etc. ... It was then a question of recovering this residue for reuse "as is", as an addition of aqueous liquid in the process, considering that it was simply a liquid, to be recovered in order to reduce the consumption of water and / or chemical product (acid of the impregnation liquor for example) of the process.

[0022] Now this extracted residue, if it could indeed include a high proportion of liquid (water), also included solid matter (if only in the case of washing the feeding equipment with water to avoid fouling it): we are dealing with a liquid loaded with solid particles.

[0023] And it was pointed out by the inventors that, once separated from the rest of the extracted residue, this solid residue (these particles) had a very interesting and valuable composition: Thus, a solid residue, derived from a solid-liquid residue extracted from a feeding device of an impregnation reactor, contains sugar polymers, lignin and has a formulation very close to that of the biomass which entered the feeding device, which can be either native biomass or biomass which has already undergone one or more treatments (mechanical treatment such as grinding, iron removal, or chemical treatment such as adding water to adjust the dry matter content of the biomass before impregnation or other treatment). A solid residue, derived from a solid-liquid residue extracted from a reactor feed device, may have a formulation that differs from the native biomass, particularly if the latter has been previously impregnated with an acidic, basic, or oxidizing liquor and / or has undergone other pretreatments. In the case of impregnation with a liquor, for example, an acidic one, the residue may contain traces of this liquor (for example, it may contain an acid that is part of the liquor formulation). It may also contain less hemicellulose, some of which may have been converted into sugars by the impregnation liquor, and it may also contain less cellulose and lignin. This residue may also contain fewer extractable species (monomeric sugars, ash, etc.) than the biomass, since the impregnation process affects these soluble species.

[0024] The invention then took advantage of these observations to separately valorize this solid residue in order to best improve the performance of the process as a whole, with a whole series of advantages: - By separating the solid-liquid residue, we can recover a liquid residue that is free or substantially free of solid particles, which allows for wider recycling of this liquid (the particles do not disrupt / risk fouling equipment that recirculates wash water, for example). - By recycling the separated solid residue, the yield of the biomass-to-sugar conversion process is increased (through pretreatment generating sugars, particularly C5 sugars, followed by enzymatic hydrolysis generating C6 sugars) or the biomass-to-ethanol conversion process (through pretreatment, enzymatic hydrolysis, and fermentation), since the biomass is reincorporated into the conversion process. or a biomass derivative that would otherwise be lost and that includes sugars / components still capable of being converted into sugars) - The liquid residue freed from solid particles can be used to reduce the water consumption of the process: the solid-liquid residue from the feeding device of a cooking reactor can thus contain up to 80% water by weight, recovering this water is therefore very interesting, the process being water-intensive, and even the solid-liquid residue extracted from the feeding device of the impregnation reactor can include a significant water content, which is at least the water content of the native biomass, a content that varies according to the nature of the biomass but which can reach at least 30% by weight. The liquid residue from the solid-liquid residue extracted in the feed system of a cooking reactor, originating from acid-impregnated biomass, will contain a certain amount of acid and can therefore be used as a supplement to produce impregnation liquor, thus reducing the acid consumption of the process (obviously, the same benefit of reduced chemical consumption applies if the impregnation is carried out with a basic or oxidizing liquor). This liquid residue can also be used to adjust, for example, the pH / amount of oxidizing agent contained in the impregnation liquor and present in residual form in the biomass at various stages of its conversion process, apart from the preparation of the impregnation liquor itself.

[0025] According to the invention, washing of the or at least one of the feeding devices can be achieved by circulating a washing fluid between a washing inlet and a washing outlet of said feeding device, the washing outlet preferably also being the solid-liquid residue extraction outlet.

[0026] In this case, the solid-liquid residue contains a high liquid (water) content, since it includes the water contained in the biomass and the wash water.

[0027] According to the invention, at least part of the liquid residue can be reintroduced into the same feeding device, or into one of said feeding devices in the case of a plurality of reactors.

[0028] In one variant, the solid residue from a feeding device of an impregnation reactor can be reintroduced into the inlet of the feeding device, for example jointly with the biomass feed entering the device.

[0029] In another variant, the solid residue from a feeding device of a cooking reactor can be reintroduced into the inlet of the feeding device, for example in conjunction with the biomass load entering the device, which optionally has been impregnated beforehand.

[0030] It is also possible that the solid residue from a feeding device of an impregnation reactor is returned to the feeding device of the reactor of cooking (or vice versa), with less favorable impact, however, on biomass conversion yield than in the two previous variants.

[0031] Advantageously, at least one of the feeding devices creates a pressure increase between the biomass inlet and the biomass outlet of said device, this pressure increase generating a compression of the biomass leading to the extraction of the solid-liquid residue.

[0032] At least one of the feeding devices may be a feed screw, in particular at least partially conical, comprising a casing with a cage having openings that allow the extraction of the solid-liquid residue from the biomass and optionally the circulation of a washing fluid. This compression screw (also called a "plug screw" in Anglo-Saxon terminology) creates a hermetic plug of biomass in the downstream portion of the screw, which compresses the biomass, resulting in a pressure difference between the biomass inlet and outlet of the screw, for example, of at least 0.05 MPa, for example, approximately 0.5 MPa. The compression applied to the biomass can thus lead to the expulsion of some of the liquid contained in the biomass, particularly when the dry matter content of the biomass is less than 80% before it enters the pressurized feeding means.

[0033] According to the invention, the solid-liquid residue can be separated into a solid residue and a liquid residue by at least one separation device chosen from a centrifugation device, a draining or pressing device, a screen.

[0034] The process according to the invention may include a step of impregnating the biomass with an impregnation liquor containing a chemical catalyst, said step being carried out by introducing the biomass into the reactor or one of the reactors by its / their feeding device.

[0035] The process according to the invention may include a step of treating the biomass by steam cooking or explosion, said step being implemented by introducing the biomass into the reactor or one of the reactors by probe feeding device.

[0036] The process according to the invention may include at least one step of treating biomass by enzymatic hydrolysis, said step being subsequent to its cooking or steam explosion, in an enzymatic hydrolysis reactor equipped with its feeding device. The feeding device of this reactor is conventional; it may, for example, be a screw conveyor (generally no biomass compression at this stage).

[0037] The process according to the invention may include at least one step of treating biomass by fermentation, said step being subsequent to or concurrent with the enzymatic hydrolysis step, in a fermentation reactor equipped with its feeding device. The feeding device of this fermentation reactor If conventional, it might, for example, be a screw conveyor (generally without biomass compression at this stage). Note that enzymatic hydrolysis and fermentation can also be carried out in the same reactor.

[0038] The process according to the invention may include at least one biomass treatment step for separating solvents or alcohols, said step being subsequent to the fermentation step and being carried out in a separation reactor equipped with its feeding device. As detailed below, this reactor may be any equipment, including, in particular, at least one distillation column, its feeding device being any conventional device for this type of equipment.

[0039] According to one embodiment of the invention, a residue can be extracted from the biomass during its passage through the feeding device towards the impregnation reactor and / or towards the cooking reactor, by means of an extraction outlet provided in said device, said residue, referred to as solid-liquid residue, being a mixture of solid and liquid, - then said solid-liquid residue is separated into a solid residue and a liquid residue, - and at least a part of the solid residue is reintroduced into the same feeding device (of the impregnation or cooking reactor) or into at least one of the feeding devices of the enzymatic hydrolysis reactor or the fermentation reactor or the separation reactor.

[0040] In this configuration, a solid residue from a pretreatment of biomass (cooking with optional prior impregnation) is therefore reused to introduce it into a reactor downstream of the pretreatment reactor(s), which aim to convert the pretreated biomass (at the outlet of the cooking reactor) into sugars, (we then speak of hydrolysate) and then possibly into a solvent or alcohol of the ethanol type (we then speak of fermentation must from which the alcohol or solvent of interest is separated in a known way).

[0041] According to one embodiment, the process according to the invention may comprise the following steps - a) Preparation of an impregnation liquor containing a chemical catalyst for the impregnation of biomass, the catalyst being chosen from an acid catalyst, a basic catalyst and an oxidizing catalyst, and preferably an acid catalyst, in a preparation area, - b) Introduction of biomass into an impregnation reactor using a first feeding device, said first feeding device being washed by circulation of a first washing fluid between a washing inlet and a washing outlet of said device (6), - c) Introduction of the liquor into the impregnation reactor via a first liquor inlet (4) of the reactor, - d) Transfer of the impregnated and then drained biomass from an outlet of the impregnation reactor to an inlet of a pretreatment reactor by cooking by at least a second feeding device, said second feeding device being washed by circulation of a second washing fluid between a washing inlet and a washing outlet of said feeding device, - e) Pretreatment of said biomass in said reactor by steam cooking or explosion, - f) Extraction from biomass of a solid-liquid residue passing through at least one of the two feeding devices, then separation of said / of each of the solid-liquid residues into a solid residue and a liquid residue with reintroduction of at least a part of the solid residue as biomass supplement in at least one of the feeding devices, and reintroduction of at least a part of the liquid residue as washing fluid supplement in at least one of the feeding devices or as supplement for the impregnation liquor in the liquor preparation area or in the impregnation reactor.

[0042] The invention also relates to any installation implementing the process described above.

[0043] The installation according to the invention may thus comprise at least one biomass processing reactor, said reactor being equipped with a biomass feeding device having a biomass inlet and a biomass outlet, said biomass outlet being in fluidic connection with an inlet of the reactor, with extraction from the biomass, as it passes through the feeding device to the reactor, of a residue via an extraction outlet provided in said device, said residue, referred to as solid-liquid residue, being a mixture of solid and liquid, the installation also comprising - at least one device for separating said solid-liquid residue into a solid residue and a liquid residue, in particular selected from a centrifugation device, a draining or pressing device, a screening device, - means for reintroducing at least part of the solid residue into the same feed device, or into one of said feed devices in the case of a plurality of reactors - possibly means to reintroduce at least part of the liquid residue into the installation, in particular into the / one of the feeding devices.

[0044] The means for reintroducing the liquid and / or solid residues are conventional, and may include any suitable hydraulic connection means (pipes, pump-type equipment, filter, valves).

[0045] The invention also relates to the use of the process or installation as described above for the treatment of lignocellulosic biomass, such as wood, straw, agricultural residues, and all dedicated energy crops, including annual or perennial plants such as miscanthus, with a view to producing sugars, biofuels or bio-based molecules. List of figures

[0046] [Fig.1]

[0047] Fig. 1 is a schematic representation of a lignocellulosic biomass conversion plant where the process according to the invention can be applied.

[0048] [Fig.2]

[0049] The [Fig.2] is a block diagram of the process according to a prior art implementing the installation of the [Fig.1].

[0050] [Fig.3]

[0051] Fig. 3 is a block diagram of a part of the process according to the invention, modifying the process according to Fig. 2.

[0052] [Fig.4]

[0053] Fig. 4 is a block diagram illustrating a first variant of the process according to the invention.

[0054] [Fig.5]

[0055] Fig. 5 is a block diagram illustrating a second variant of the method according to the invention.

[0056] [Fig.6]

[0057] Fig. 6 is a block diagram illustrating a third variant of the method according to the invention.

[0058] [Fig.7]

[0059] Fig. 7 is a block diagram illustrating a fourth variant of the method according to the invention.

[0060] [Fig.8]

[0061] Figure 8 is a block diagram illustrating a fifth variant of the method according to the invention.

[0062] [Fig.9]

[0063] [Fig.9] is a schematic representation of a variant according to the invention of the lignocellulosic biomass conversion plant described in [Fig.1].

[0064] Note that the same references concern the same flow, the same device, from one figure to the other. Description of the implementation methods

[0065] Figure 1 represents, in a very schematic way, a non-limiting example of a lignocellulosic biomass conversion plant in which the invention can be applied, a plant which provides for a pretreatment of the biomass including impregnation with an acidic liquor followed by steam cooking / explosion, then enzymatic hydrolysis followed by alcoholic fermentation, to transform the biomass into ethanol.

[0066] The invention applies similarly to different installations, in particular: - installations which are only intended for the production of sugars, and which therefore do not provide for alcoholic fermentation, - installations which provide for pretreatment by cooking without prior impregnation by a liquor (autolysis for example), - installations which provide for pretreatment by cooking with prior impregnation by a non-acidic liquor, for example a basic or oxidizing liquor.

[0067] The invention is indeed intended to be applied to any reactor, including, but not limited to, impregnation and cooking reactors, used in a biomass conversion process.

[0068] Fig. 1 therefore represents a biomass conversion carried out as follows: the crushed biomass 5 (impregnated or not with a catalytic liquor) is introduced into an impregnation reactor 9 by a pressurized feeding means 6 which is a screw, also called in English "Plug Screw Feeder", the terminal portion of which is conical, which has a fairing with a draining grid, a wash water inlet 7 and a wash water outlet 8. A hermetic plug of biomass is created in the downstream portion of the screw, which creates a compression on the biomass resulting in a pressure difference between the biomass inlet and the biomass outlet of the screw of at least 0.05 MPa. The compression applied to the biomass can lead to the expulsion of some of the liquid contained in the biomass, particularly when the dry matter of the biomass is less than 80% before it enters the pressurized feeding means 6.The liquid thus extracted mixes with the wash water and is drawn off with the waste wash water 8. .

[0069] The impregnation reactor is also supplied with acid liquor 4 (water with added sulfuric acid) from a liquor preparation tank 3, itself supplied with acid 2 and water 1. The reactor includes a biomass impregnation zone 9a, surmounted by a biomass draining zone 9b.

[0070] The impregnated and drained biomass 10 exits reactor 9 to feed a steam explosion cooking reactor 14 via another feed screw 11 similar in operation to feed screw 6. In this screw, due to the compression exerted on the biomass, a liquid 13 resulting from this pressing, also called pressate, is recovered, which is composed of water and acid. The screw is washed, using a dedicated inlet, by a washing liquid 12 (water and / or a recycled liquid, as described later), which is then discharged through the outlet through which the pressate 13 is also discharged.

[0071] Reactor 14 is also supplied with steam 15. At the outlet of reactor 14, the biomass-steam mixture passes into a biomass 19 and steam 18 separation tool 17. The biomass 19 is then treated in an enzymatic hydrolysis reactor 20, and once hydrolyzed into sugars, the hydrolyzed biomass 21 (also called hydrolysis mash) passes into an alcoholic fermentation reactor 22. The biomass fermented into alcohol 23 (also called fermentation mash) is then fed into one or more distillation columns to obtain concentrated alcohol 25 and crude vinasse 26.

[0072] This is just one example of an installation, which can also have many variations. Thus, enzymatic hydrolysis and fermentation can be carried out simultaneously in the same reactor; this is then referred to as SSCF for "Simultaneous Saccharification and Co-Fermentation".

[0073] 1: Water inlet into the liquor preparation tank 2: Acid enters the liquor preparation tank 3: Tool (tank) for preparing the liqueur 4: Acidic liquid to impregnation tool (reactor) 5: Crushed biomass 6: Screw ("plug-screw feeder") of the impregnation tool 7: Wash water from the plug-screw feeder of the impregnation tool 8: Wash liquid outlet from the "plug screw feeder" 6 of the impregnation tool 9: Impregnation tool (reactor) 9a: Impregnation zone of the impregnation tank 9 9b: Drip zone of the impregnation tank 9 10: Impregnated and drained biomass 11: Pretreatment tool plug-screw feeder 12: Wash water from the "plug screw feeder" of the pretreatment tool 13: Pressing the "plug screw feeder" of the pretreatment tool 14: Pretreatment cooking tool (explosion reactor) 15: Steam injection for pretreatment 16: Pre-treated biomass and steam 17: Steam and pre-treated biomass separation tool (cyclone) 18: Vapor to condensation 19: Pre-treated biomass 20: Enzymatic hydrolysis reactor 21: Hydrolysate containing sugars 22: Alcoholic (ethanolic) fermentation reactor 23: Fermented wine containing ethanol (alcohol) 24: Ethanol recovery device, for example a distillation column(s) 25: Concentrated alcohol 26: Residues (solids and liquids, mixed or separated according to the arrangement of 24)

[0074] The process Below is a more detailed description of the different stages of a biomass conversion process using such an installation and to which the invention can advantageously be applied: (this is an example to which the invention is not limited).

[0075] Step a) conditioning of lignocellulosic biomass The treatment process begins with a conditioning stage for the lignocellulosic biomass, involving at least one grinding to obtain biomass particles no larger than 300 mm. Several successive grinding stages can be performed to achieve the desired particle size. Generally, the ground biomass has a particle size (the largest size) of no more than 300 mm, most often at least 1 mm, and frequently between 2 and 200 mm. Any method known to those skilled in the art can be used for this stage. Straw is usually ground using screens with a mesh size of 5 to 100 mm. Wood is generally chipped into parallelepiped-shaped pieces with a length of 20 to 160 mm, a width of 10 to 100 mm, and a thickness of 2 to 20 mm.The ground lignocellulosic biomass is moved to the next stage by any means known to those skilled in the art, in particular a transfer screw.

[0076] Step b) of impregnation with an acidic liquid

[0077] The treatment process according to the invention includes a step b) of impregnating the lignocellulosic substrate with an acidic liquor so as to obtain an impregnated lignocellulosic substrate having a pH between 0.1 and 3. This step aims to prepare the lignocellulosic substrate for the pretreatment step.

[0078] The impregnation is carried out in an impregnation reactor at a temperature between 10 and 90°C and preferably at atmospheric pressure. The residence time of the lignocellulosic substrate in the impregnation reactor is usually from 10 seconds to 180 minutes, preferably between 30 seconds and 60 minutes, and even more preferably between 30 seconds and 15 minutes. Preferably, the impregnation step is carried out in a single step.

[0079] The impregnation reactor or impregnator is equipped with one or more screws that transfer the lignocellulosic substrate from its inlet to the outlet. The impregnator is also equipped with one or more lines for supplying the acidic liquor and, if necessary, one or more lines for withdrawing the acidic liquor. These inlet and outlet lines for the acidic liquor are generally installed to operate in co-current or counter-current recirculation.

[0080] The acid liquor is an aqueous solution of a strong acid which is for example chosen from sulfuric acid, hydrochloric acid, nitric acid, for example at an acid content of between 0.5 and 4% by weight.

[0081] Step c) of solid / liquid separation on the lignocellulosic substrate impregnated with acidic liquor

[0082] According to step c) of the treatment process according to the invention, the lignocellulosic substrate impregnated with acid liquor is subjected to a solid / liquid separation step to obtain a lignocellulosic substrate having a dry matter content of between 15% and 70% by weight and a spent acid liquor. Preferably, the lignocellulosic substrate impregnated with acid liquor is first drained to extract at least some of the free acid liquor before being treated by solid / liquid separation.

[0083] The solid / liquid separation step can be implemented using any technique known to a person skilled in the art, which may be, for example, decantation, centrifugation or pressing.

[0084] Preferably, the lignocellulosic substrate is pressed concurrently with its transfer to pretreatment step d) when the latter employs the steam explosion process described below. This method of conducting step c) is, for example, achieved by a screw called a "plug screw feeder," the operation of which has already been described above. The formation of a plug of pressed lignocellulosic substrate ensures the pressure-tightness of the steam explosion reactor, thus preventing dangerous steam leaks. The transfer screw is also equipped with one or more lines for withdrawing the spent liquor (called pressate) separated during pressing. The pressate can be recycled in impregnation step b) and / or in the washing step by the washing liquid 12 passing through the feed screw 11.

[0085] The wet biomass obtained at the end of step c) of solid / liquid separation, which can be designated by the term "washed and acidified lignocellulosic substrate", has a dry matter content preferably between 15% and 70% by weight, and more preferably between 40% and 65% by weight.

[0086] Step d) of pretreatment of the washed and acidified lignocellulosic substrate

[0087] The washed and acidified lignocellulosic substrate, in accordance with step c) of the process, undergoes a pretreatment step d).

[0088] Cellulose (and possibly hemicelluloses), which are the targets of enzymatic hydrolysis, are not directly accessible to enzymes. This is why a pretreatment of the biomass is carried out before the enzymatic hydrolysis step. The pretreatment aims in particular to modify the physical and physicochemical properties of the cellulosic fraction, such as its degree of polymerization and its state of crystallinity.

[0089] Various types of pretreatment are known to those skilled in the art; they combine chemical and thermal treatments. Examples include acid or basic baking, the organosolv process, ionic liquid treatments, and the steam explosion process.

[0090] The preferred pretreatment process is steam explosion (or "SteamEx" or "Steam Explosion" in Anglo-Saxon terminology) carried out in an acidic medium. This process involves rapidly heating the lignocellulosic substrate to a high temperature by injecting pressurized steam. The treatment is stopped by abrupt decompression.

[0091] The operating conditions of the steam explosion process are as follows: - the steam is injected directly into the reactor; - The reactor temperature is generally between 150 and 220°C, preferably between 170°C and 210°C. - The pressure is between 5 and 25 bar absolute (0.5 and 2.5 MPa), more preferably between 8 and 19 bar absolute (0.8 to 1.9 MPa), - the residence time before the expansion phase varies from 10 seconds to 50 minutes, and preferably between 3 minutes and 30 or 40 minutes

[0092] The steam explosion can be carried out in batch or continuous operation and the depressurization step which allows the biomass to be broken down can take place in one or more steps.

[0093] At the end of the pretreatment step by steam explosion, a pretreated lignocellulosic substrate with a high dry matter content, generally between 20 and 70% by weight, is obtained, and a vapor phase which is then condensed.

[0094] Within the framework of the invention, the pre-treated lignocellulosic substrate obtained at the end of step d) of the treatment process according to the invention is advantageously used as a feedstock in a so-called second generation process for the production of solvents and / or alcohols from lignocellulosic biomass.

[0095] The invention also relates to a process for producing solvents and / or alcohols from lignocellulosic biomass, comprising at least the following steps: (i) said lignocellulosic biomass is treated by the treatment process according to the invention so as to obtain a treated lignocellulosic substrate; ii) enzymatic hydrolysis of the treated lignocellulosic substrate is carried out in order to obtain a hydrolysate containing fermentable sugars; iii) the hydrolysate from step ii) is fermented to obtain a fermentation wort containing solvents and / or alcohols; iv) a separation of solvents and / or alcohols from the fermentation must is carried out.

[0096] Following steam explosion under acidic conditions, the pretreated lignocellulosic substrate generally has a pH lower than that compatible with the medium for enzymatic hydrolysis. Thus, the lignocellulosic substrate treated according to step i) of the solvent and / or alcohol production process is subjected to a neutralization step to bring its pH to a value between 4 and 6.

[0097] For the neutralization step, an aqueous solution containing a neutralizing agent is used. This neutralizing agent can be chosen from any weak or strong base known to those skilled in the art. By the term "base," we mean any chemical species which, when added to water, gives an aqueous solution with a pH greater than 7. Preferably, the neutralizing agent is chosen from potassium hydroxide, sodium hydroxide, ammonia, or lime. Even more preferably, the neutralizing agent is chosen from potassium hydroxide and ammonia, alone or in combination. Preferably, the neutralizing agent is used in aqueous solution, with a mass concentration between 2% and 75%, and even more preferably between 20% and 70%.

[0098] Neutralization is carried out at a temperature between 15°C and 95°C, and preferably between 20°C and 70°C. In general, the temperature of the neutralization step is not precisely controlled and is simply governed by the heat released by the acid-base neutralization reaction.

[0099] The neutralization step can be carried out continuously, discontinuously or discontinuously fed-batch.

[0100] It should be noted that an optional washing step may be carried out before or after the neutralization step, on all or part of the pre-treated lignocellulosic substrate.

[0101] If a wash is applied, a liquid stream is brought into contact with the pretreated lignocellulosic substrate, and then the liquid is separated from the solid. The washing step can be carried out by percolation, by successive liquid / solid mixing and separation operations, by belt filter washing, or by any other technique known to those skilled in the art. The washing liquid used can be water or a process stream. The mass ratio between the added washing liquid and the liquid contained in the substrate to be washed is generally between 0.5 and 4. The washing step generates a sugary wash juice containing some of the hemicelluloses solubilized during the pretreatment. This wash juice can, for example, be used as a carbon source for the production of biocatalysts (enzymes and / or microorganisms). The washing step is generally carried out at a temperature between 10°C and 95°C.

[0102] Step ii) of enzymatic hydrolysis

[0103] The pre-treated lignocellulosic substrate, optionally neutralized and washed, is sent to the enzymatic hydrolysis step ii) of the process.

[0104] The pre-treated lignocellulosic substrate which is sent to the enzymatic hydrolysis step has a dry matter content generally between 15% and 70% by weight.

[0105] The objective of enzymatic hydrolysis is to hydrolyze (depolymerize), by means of biocatalysts, hemicelluloses and cellulose into fermentable sugars, preferably glucose.

[0106] The enzymatic hydrolysis step is carried out under mild conditions, at a temperature of approximately 40°C to 55°C, preferably between 45°C and 50°C, and at a pH of 4.0 to 5.5, and even more preferably between 4.8 and 5.2. The dry matter content of the enzymatic hydrolysis medium is between 5 and 45% by weight, preferably between 10 and 30% by weight. It is carried out using enzymes produced by a microorganism. Natural or genetically modified microorganisms, such as fungi belonging to the genera Trichoderma, Aspergillus, Penicillium, or Schizophyllum, or anaerobic bacteria belonging, for example, to the genus Clostridium, produce a cocktail of enzymes containing, in particular, cellulases and hemicellulases, adapted to the extensive hydrolysis of cellulose and hemicelluloses.

[0107] Enzymatic hydrolysis can be carried out in continuous or batch mode, or in continuous fed mode, in one or more reactors. The residence time is between 12 hours and 200 hours and preferably between 24 hours and 120 hours and even more preferably between 48 hours and 120 hours.

[0108] At the end of step ii) a hydrolysate containing fermentable sugars is recovered from the bioreactor which is then treated in step iii) of fermentation.

[0109] It should be noted that the hydrolysate obtained may optionally undergo one or more treatment steps before the fermentation step. For example, this may involve pH adjustment, partial purification to limit the content of compounds that inhibit the fermenting microorganism, or at least partial separation of the solid residues contained in the hydrolysate.

[0110] Step iii) of fermentation of the hydrolysate

[0111] According to step iii) of the solvent and / or alcohol production process, the hydrolysate, if treated, is sent to the fermentation step, which allows the conversion of fermentable sugars into solvent and / or alcohols of interest by means of one or more microorganisms of different genera. The fermentation methods are known to those skilled in the art and are described in particular in US patent 8,456,633.

[0112] The term "solvent" means organic compounds other than alcohols, for example organic compounds having a ketone function such as acetone.

[0113] The term "alcohol" includes, in particular, ethanol, propanol, isopropanol and butanol.

[0114] Natural or genetically modified microorganisms may be chosen for example from Saccharomyces cerevisiae, Schizosaccharomyces pombe, Saccharomyces uvarum, Saccharomyces diastaticus, Kluyveromyces fragilis, Candida shehatae, Pichia stipitis, Pachysolen tannophilis or the bacteria Zymomonas mobilis, Clostridium acetobutylicum, Escherichia coli.

[0115] In the context of the invention, the fermentation step allows, for example, the production of ethanol alone or in a mixture with butanol, propanol, isopropanol and / or acetone. For example, the fermentative microorganism may be capable of producing a mixture called "ABE (acetone-butanol-ethanol)" or "IBE (isopropanol-butanol-ethanol)".

[0116] Preferably, the chosen microorganism is a natural or genetically modified yeast of the genus Saccharomyces capable of producing ethanol.

[0117] At the end of step iii) a fermentation must diluted in products of interest is recovered.

[0118] According to one embodiment of the process, steps ii) and iii) are carried out simultaneously in at least one bioreactor so that enzymatic hydrolysis and fermentation are carried out simultaneously according to a process designated by the term "Simultaneous Saccharification and Fermentation (SFS)" or "Shnultaneous Saccharification and Fermentation (SSF)" according to Anglo-Saxon terminology. When the hydrolysis step is combined with the fermentation step, the operating conditions, particularly temperature, can be adjusted to suit the tolerances of the fermenting microorganism. For example, the temperature can be lowered to between 28°C and 45°C, and preferably to between 30°C and 35°C when fermentation is carried out with a yeast of the genus Saccharomyces. The pH is preferably adjusted to between 5 and 5.5 to promote yeast performance.

[0119] The production unit implementing the process according to the invention may include, in addition to the installations already described, in situ production units for enzymes and / or yeasts.

[0120] Step iv) of separating solvents and / or alcohols from the fermentation must.

[0121] The process according to the invention finally includes a step of separating the product(s) of interest from the fermentation must possibly preceded by a solid / liquid separation step in order to remove at least a fraction of the solid matter contained in the fermentation must.

[0122] Preferably the step of separating the product(s) of interest, for example ethanol, implements one or more distillations which is a technology well known to those skilled in the art.

[0123] The load: lignocellulosic biomass According to the invention, the process feed can be biomass alone or in mixtures. The amount of water contained in the raw feed is generally at least 10%, in particular between 10 and 70% by mass.

[0124] The raw biomass is selected from any type of biomass, preferably solid biomass, and in particular lignocellulosic biomass. Non-limiting examples of biomass types include, for example, agricultural residues (in particular straw, corn cobs), forestry residues, forestry products, sawmill residues, dedicated crops such as short-rotation coppice.

[0125] Preferably, the raw biomass, also called native biomass, is lignocellulosic biomass. It essentially comprises three natural constituents present in varying quantities depending on its origin: cellulose, hemicellulose and lignin. Lignocellulosic biomass feedstock is preferably used in its raw form, that is to say in the entirety of its three constituents: cellulose, hemicellulose and lignin.

[0126] In a preferred embodiment of the invention, the lignocellulosic biomass is chosen from grass biomass, agricultural residues such as straw waste, corn cobs, sugar cane bagasse, forestry or sawmill residues such as wood chips or any other type of woody residue.

[0127] The impregnation fluid: The optional fluid injected for impregnation is an aqueous liquid solution, with or without acid, at a temperature between 10 and 95°C and at atmospheric pressure. The pH of this chemical solution is between 0.1 and 12.0, preferably between 0.1 and 7, and more preferably between 0.3 and 2. In a preferred embodiment, the solution used is an acid-catalyzed solution, and its pH is set between 0.1 and 4, in particular between 0.3 and 2. For example, at least one acid may be used, selected from sulfuric acid, hydrochloric acid, nitric acid, or oxalic acid. Their concentration in the aqueous phase is preferably between 0.2 and 8% by weight.

[0128] Let us examine Figures 2 to 8 one by one: All these figures are variations of a biomass pretreatment. Note that they are described by proposing impregnation with an acidic fluid followed by steam explosion cooking, to illustrate the invention simply, but that the invention applies equally well to a pretreatment without impregnation, or with non-acid impregnation, or even to cooking without steam explosion.

[0129] Figure 2 shows the schematic of the pretreatment section of the biomass conversion process, which can, for example, be applied to the installation of Figure 1. The process involves a known sequence of (optional) impregnation with an impregnation fluid followed by steam cooking / explosion of the biomass, which the invention modifies: The (crushed) biomass 5 enters a transfer zone comprising a screw-type feeder 6, which can optionally be washed by circulating a washing fluid 7 such as water (discharged as used washing fluid 8). This conveys the biomass into the impregnation reactor 9, which is also supplied with impregnation fluid 4 by a preparation tank 3 supplied with water 1 and an impregnation compound 2 (acidic or basic type). As mentioned above, impregnation may not be required.Impregnation can also be carried out differently, in batch (soaking the biomass in a tank containing the impregnation fluid), or continuously, for example by spraying, or by passing the biomass through a stirred reactor.

[0130] Thus, a different feeding method and impregnation method can be used, such as a conveyor belt bringing the biomass under an impregnation fluid spraying device.

[0131] The impregnated biomass 10 then passes into a transfer zone comprising a feed compression screw 11, washed by a washing fluid 12 (wash water), the waste wash water 13 being discharged. The biomass then feeds a cooking reactor 14 in the presence of steam 15, and is then extracted from the reactor as pre-treated biomass 16, to continue its conversion process into sugars or alcohol.

[0132] Figure 3 highlights the first step of the modification by the invention of the process according to Figure 2: The fluid 8 extracted from the feed device 6 of the impregnation reactor 9, which can be water from the native biomass (or water added to the biomass before entering the feed device) and / or waste wash water from the wash water 7. This fluid 8 is in fact composed of a liquid phase (water) and suspended solid particles (biomass). According to the invention, it is conveyed to a solid / liquid separation device 30, at the outlet of which a liquid phase / residue 31 and a solid residue 32 are recovered. This could be, for example, a screening device. These two residues can thus be recovered / reused separately in a very advantageous manner, as described later.

[0133] Similarly, the fluid 13 extracted from the feed device 11 of the cooking reactor 14 also consists of a liquid phase (water) and suspended solid particles (biomass). According to the invention, it is conveyed to a solid / liquid separation device 40, at the outlet of which a liquid phase / residue 41 and a solid residue 42 are recovered. This could, for example, also be a screening device. These two residues can thus be recovered / reused separately in a very advantageous way, as described later.

[0134] This separation and these valorizations / reuses of solid and liquid residues can be carried out only on the feeding device of the impregnation device / reactor 9 or only on that of the cooking device / reactor 14, or on both devices, naturally.

[0135] Fig. 4 illustrates a valorization of the solid residue 32 (impregnation stage), by reinjection of the residue 32 with the biomass load 5 into the feed device 6. In this case, the solid residue 32 has a composition close to, or even identical to, that of the biomass 5, but it may be in the form of smaller particles (when the feed device is of the compression screw type, which has a mechanical action on the biomass).

[0136] Recycling the solid residue 32 at the inlet of the impregnation reactor 9 with the ground biomass 5 prevents the loss of this solid stream and yields a "clear" liquid residue 31 (free of visible suspended particles), which is also reusable. This solid recycling increases the process yield, since the residue 32 contains sugar polymers, increases the lignin yield, since the residue 32 contains lignin, and reduces the process water consumption, since the residue also contains water. The solid / liquid separation can be performed on all or part of the stream 8 exiting the feeder 6, and this recycling of the solid residue 32 can be performed on all or part of said solid residue.

[0137] Fig. 5 illustrates the valorization of the solid residue 42 (cooking stage), by reinjection of the residue 42 into the inlet of the feeding device 12 of the cooking device / reactor 14. In this case, the solid residue 42 has a different composition from the residue 32, insofar as it was obtained from biomass impregnated by an impregnation liquid, in particular strongly acidic, and / or from wash waters of the feeding device which may also contain a certain content of this fluid / acid. Recycling the solid residue 42 with the impregnated biomass 10 prevents the loss of this solid stream and yields a clear liquid residue 41 (also called pressd biomass). This solid recycling increases the process efficiency, since the stream 42 contains sugar polymers, increases the lignin yield, since the stream 42 contains lignin, and reduces the consumption of the impregnation liquid 2, since the residue 42 contains impregnation liquid. The solid / liquid separation can be performed on all or part of the stream 13 exiting the feeding device 11, and this recycling of the solid residue 42 can be performed on all or part of said solid residue.

[0138] It is also possible to recycle all or part of the solid residue 42 with the ground biomass 5 as input for impregnation, but this recycling appears less advantageous, because a second impregnation of the biomass, already acidic, of the residue 42 is then carried out.

[0139] Figure 6 shows both the reinjection of solid residue 32 according to Figure 4 and that of solid residue 42 according to Figure 5, and thus illustrates an embodiment where the invention is applied twice in the biomass conversion process, with the same advantages as those described in Figures 4 and 5. Each reuse of the two solid residues can be carried out on all or part of each residue. It is also possible to combine all or part of the two solid residues for joint reuse in the process.

[0140] Figure 7 represents the reinjection of the two solid residues 32 and 42 in accordance with Figure 6, but also the reuse of the two corresponding liquid residues 31 and 41: - The liquid residue 31 is reinjected into the washing inlet of the feeding device 6 of the impregnation device; it is essentially water. - The liquid residue 41 is reinjected into the tank for preparing the impregnation liquor. Indeed, this residue 41 contains a certain amount of acid (if we continue to take the example of an acid liquor), and reinjecting it into tank 3 provides a useful addition of water and acid.

[0141] Recycling liquid residues 31 and 41 reduces water and impregnation fluid consumption. This recycling can be done on all or part of the liquid residues. As with solid residues, it is also possible to consider grouping them, at least partially, for joint recycling in the process.

[0142] Figure 8 proposes variations, compared to Figure 7, for reusing the liquid residues 31 and 41: the dashed arrows indicate different possibilities, alternative or cumulative, for reinjecting them, in whole or in part, into the biomass pretreatment process. Thus, the liquid residue 31 (upstream of the impregnation device) can also be reinjected, in whole or in part, into the impregnation liquor preparation tank 3 as a water supplement. It can also be reinjected, in whole or in part, as wash water 12 for the feed device 11 of the cooking device 14, or as wash water 7 for the feed device 6 of the impregnation device 9, if washing is also planned for this device. It can also be added, in whole or in part, to the liquid residue 41 and follow its reinjection circuit.Conversely, the liquid residue 41 can also, in whole or in part, be added to the liquid residue 31, before being jointly reused in the tank 3 for preparing the liquor 4 for example (these two variants are not shown in the figures).

[0143] It should also be noted that these liquid residues 31, 41, and in particular at least residue 41 which contains acid, can also be reused / reinjected directly into the impregnation device 9, if its acid content is preferably controlled upstream. Finally, it should be noted that at least one of these liquid residues 31, 41 can also be reused in the biomass conversion process downstream of its pretreatment, in a step subsequent to its cooking that requires an input of water and / or an input of water having an acidic pH.

[0144] Figure 9 proposes a modification according to the invention of the installation described in Figure 1: here, the two solid residues from the feeding devices of the impregnation reactor 9 and the cooking reactor 14, or at least one of them, are at least partially reintroduced downstream of the biomass pretreatment. The dashed lines indicate the various alternative or cumulative options for reintroducing these solid residues, in whole or in part: they can therefore be reintroduced at the inlet of the hydrolysis reactor 20 or the fermentation reactor 22 or even at the inlet of the separation equipment 24, notably via their own conventional feeding devices (for example, one or more pipes or a screw conveyor system opening into an inlet in the reactor). The solid residue thus mixes with the pretreated biomass stream 19, and / or the hydrolysate stream 21 and / or the fermentation mash 23.

[0145] A final option, shown in [Fig. 9], consists of directly introducing all or part of the solid residue 32 and / or 42 into the final residue 26 obtained from the separation of the fermentation wort, a residue that can be used as fuel. In this case, the quantity of final residue 26 is directly increased, thus increasing the quantity of fuel that can be reused either within the installation itself or outside the installation. This is another type of valorization, which seeks not to increase the biomass conversion efficiency of the process, but to make the best possible use of the process residues. Examples

[0146] They relate to a pretreatment process for lignocellulosic biomass involving impregnation with acid liquor followed by steam explosion, as described in [Fig. 1]. The term "potential sugar (xylose, glucose)" used hereafter defines the addition of the various sugars, regardless of their form: monomeric or polymeric sugar. Indeed, after pretreatment by cooking, some of the sugars remain in the form of sugar polymers (cellulose or hemicellulose, for example), and some of the sugars are in the form of sugar monomers (glucose or xylose, for example). This measurement can be performed using ASTM E1758-01(2020) "Standard Test Method for Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography." As defined in the standard, to express this quantity of sugars in polymer form (cellulose for example), the water from the hydrolysis of this quantity must be subtracted. Example 1 (comparative)

[0147] Biomass 5 is a lignocellulosic biomass of wheat straw. Its composition is shown in Table 1 below:

[0148] [Tables] Cellulose 34% by weight, Hemicellulose 27% by weight, Lignin 15% by weight, Water by weight, Other 14% by weight

[0149] After hydrolysis, cellulose is converted into glucose or glucose oligomers, and hemicellulose is converted into xylose or xylose oligomers.

[0150] 642 kg / h of this 5 to 50 mm ground biomass enters the process with a flow rate 200 kg / h of wash water 7. A first solid / liquid stream 8 of 203.8 kg / h exits the process; this stream contains 1.3 kg / h of potential glucose and 1.1 kg / h of potential xylose. In the impregnation stage (reactor 9), 1622.6 kg / h of water and 84.2 kg / h of sulfuric acid are added to the reactor from the preparation tank 3 and constitute the impregnation liquid 4.

[0151] At the inlet of the cooking reactor 14, the transfer zone 11 is fed with the impregnated biomass 10. The transfer zone 11 (compression screw) is washed with 4087.0 kg / h of water 12, and a second solid / liquid stream 13 of 5099.9 kg / h exits zone 11. This stream 13 contains 2.7 kg / h of potential glucose, 2.2 kg / h of potential xylose, and 45.6 kg / h of acid. The cooking reactor 14 is heated by a steam stream 15 of 3471.1 kg / h. At the outlet of this reactor 14, the pretreated biomass stream 16 of 4803.8 kg / h exits, comprising 237.8 kg / h of potential glucose and 155.2 kg / h of xylose.

[0152] At the terminals of the pretreatment, i.e., between the entry of the biomass 5 into the feeding device 6 and its exit from the cooking reactor 14, 98.1% by weight of the potential glucose and 78.8% by weight of the potential xylose were therefore retained. Example 2 (according to the invention)

[0153] It is carried out in accordance with the variant of the invention shown in [Fig. 4]: the solid residue recovered at the inlet of the impregnation reactor is recycled. The biomass load is the same as in Example 1. The flow rate is the same as for Example 1: 642 kg / h of this 50 mm ground biomass 5 enters the process with a flow rate of 200 kg / h of wash water 7. A first solid / liquid flow 8 of 203.8 kg / h exits the transfer zone 6 towards the impregnator 9. This flow is separated in a tool separation 30 into a liquid stream / residue 31 of 192 kg / h and a solid stream / residue 32 of 11.8 kg / h. The separation tool 30 is a screen.

[0154] This solid residue 32 resulting from the solid / liquid separation is relatively moist (25% dry matter) and is composed of 1.3 kg / h of potential glucose and 1.1 kg / h of potential xylose. It is recycled with the ground biomass 5 at the inlet of the feeding device 6. Surprisingly, the recycling of this solid residue 32 at the impregnation inlet does not cause accumulation in the feeding device 6 despite its small particle size and despite the fact that the solid residue initially passed through the holes in the feed screw cage: it is carried by the ground biomass 5 into the impregnation reactor 9. In the impregnation step, the same quantities of water and sulfuric acid are added to the impregnation liquid 4 preparation tank 3 as in Example 1.

[0155] The rest of the process is identical to example 1. At the outlet of the cooking reactor 14, the pre-treated biomass stream 16 of 4815.5 kg / h exits, comprising 239.2 kg / h of potential glucose and 156.1 kg / h of potential xylose.

[0156] At the end of the pretreatment (using the same definition of this term as in Example 1), 98.6% by weight of the potential glucose and 79.2% by weight of the potential xylose were retained, representing a yield increase of 1.0 percentage point. Furthermore, the invention made it possible to recycle a solid 32 that previously had no purpose. Example 3 (according to the invention)

[0157] It is carried out in accordance with the variant of the invention shown in [Fig. 5]: here, the solid residue recovered at the inlet of the cooking reactor is recycled. The same load is treated here as in the two previous examples.

[0158] 642 kg / h of this biomass 5 ground to 50 mm enters the process with a flow rate 200 kg / h of wash water 7. A first solid / liquid stream 13 of 203.8 kg / h exits the process, by compression of the impregnated biomass in the feed screw 11. This stream contains 1.3 kg / h of potential glucose and 1.1 kg / h of potential xylose. In the impregnation stage, 1622.6 kg / h of water and 84.2 kg / h of sulfuric acid are added from the impregnation liquid preparation tank 3 4.

[0159] The flow rate is the same as for Examples 1 and 2: 642 kg / h of this biomass ground to 50 mm enters the process (it enters the impregnation reactor 9) with a flow rate of 200 kg / h of wash water 7. A first solid / liquid stream 8 of 203.8 kg / h exits the process. This stream contains 1.3 kg / h of potential glucose and 1.1 kg / h of potential xylose. In the impregnation step (reactor 9), the same quantities of water are used as in Examples 1 and 2, but only 84 kg / h of sulfuric acid (a 0.2 wt% reduction compared to the previous examples) are added to the impregnation liquid preparation tank 3.

[0160] At the inlet of the cooking reactor 14, the transfer zone 11 is fed with the impregnated biomass 10. The transfer zone 11 is washed with 4087 kg / h of water 12, and a second solid / liquid stream 13 of 5097.9 kg / h exits the transfer zone 11 towards the cooking reactor 14. This stream 13 is separated in a separation tool 40, here a screen, into a liquid residue stream 41 of 5074.1 kg / h, and a solid residue stream 42 of 23.8 kg / h. This solid stream 42 resulting from the solid / liquid separation is relatively moist (26.1% DM) and is composed of 2.7 kg / h of potential glucose, 2.2 kg / h of potential xylose, and 0.2 kg / h of sulfuric acid. It is recycled with impregnated biomass 10.Surprisingly, the recycling of this residue 42 from the cooking input does not cause accumulation in the circuit in the screw-type compression feeder 11, despite its small particle size and despite the fact that the solid residue initially passed through the holes in the feeder cage. It is carried by the biomass 10 into the cooking reactor 14.

[0161] The cooking reactor 14 is heated by a steam flow 15 of 3471.1 kg / h. At the outlet of this reactor, exits the pre-treated biomass flow 16 of 4829.6 kg / h, comprising 240.5 kg / h of potential glucose and 157.4 kg / h of xylose.

[0162] At the pretreatment terminals (from the inlet of the feed device 6 to the outlet of reactor 14), 99.2% by weight of the potential glucose and 79.9% by weight of the potential xylose are retained, representing a yield increase of 2.2 percentage points. Furthermore, solid 42 was recycled, whereas it had previously had no purpose, and acid consumption was reduced by 0.2% by weight.

[0163] Table 2 below shows the compositions of the ground biomass 5 and the solid residue 32 recovered from the feeding device of the impregnation reactor 9.

[0164] [Tables2] Biomass 6 Residual so / de 32 (impregnation input) Celktee %wt 34 10.2 Hemyloxide %wt 27 8.1 Lignin %wt 15 4.5 Water %wt w: 75.0 Other 14 2.2

[0165] We can see that residue 32 has a composition very similar to that of the starting biomass, with a significantly higher water content.

[0166] Table 3 below again indicates the composition of the ground biomass 5, and that of the solid residue 42 recovered from the feeding device of the cooking reactor 14:

[0167] [Tables3] Biomass 5 Solid residue 42 (input to cooking) Celiac acid A pci s 34 10.1 Hemicellulose %wt 27 coylethanolamine Lignin %wt 15 4.5 Water %wt 10 73.9 Sulfuric acid %wt 0 0.7 Other %wt 14 2.9

[0168] We see that residue 42 has a composition similar to that of the starting biomass, with a significantly higher water content, and an additional sulfuric acid content, which justifies the interest in recycling it. Example 4 (according to the invention)

[0169] It is carried out in accordance with the variant of the invention shown in [Fig.6]: here we carry out both the recycling of the solid residue 32 recovered at the inlet of the impregnation reactor 9 and that of the solid residue 42 recovered at the inlet of the cooking reactor 14. Here we treat the same load as in the previous examples.

[0170] The flow rates resulting from the recycling described in examples 2 and 3 apply to example 4: the yield at the terminals of the pretreatment is increased by recycling these two solid residues, and the consumption of acid is reduced.

[0171] At the pretreatment terminals, 99.7% by weight of the potential glucose and 80.3% by weight of the potential xylose were retained, representing a yield increase of 3.2 percentage points. Furthermore, two solids, 32.42, which had previously had no purpose, were recycled. The combined gross flow rate of these two residues is significant, representing 6% of the gross flow rate of lignocellulosic biomass. Finally, acid consumption was reduced by 0.2% by weight.

Claims

Demands

1. Process for treating lignocellulosic biomass comprising a dry matter content of at most 90% by weight, said process comprising the use of at least one reactor (9;14) of processing said biomass, said process comprising - a step of impregnating the biomass with an impregnation liquor (4) containing a chemical catalyst, said step being carried out by introducing the biomass into an impregnation reactor (9) by its feeding device (6), - a step of treating the biomass by steam cooking or explosion, said step being carried out by introducing the impregnated biomass into a cooking reactor (14) by its feeding device (11), - then a step of treating the biomass by enzymatic hydrolysis, said step being subsequent to its steam cooking or explosion, in an enzymatic hydrolysis reactor (20) equipped with its feeding device, each biomass feeding device (6;11) being equipped with a biomass inlet and a biomass outlet, said biomass outlet being in fluidic connection with an inlet of the corresponding reactor (9;14;20), and - a residue (8;13) is extracted from the biomass during its passage through one of the feeding devices (6;11) of the impregnation reactor (9) or the cooking reactor (14) by means of an extraction outlet provided in said device, said residue, referred to as solid-liquid residue, being a mixture of solid and liquid, - said solid-liquid residue is separated into a solid residue (32;42) and a liquid residue (31;41), - and at least a part of the solid residue (32;42) is reintroduced into the same feeding device, or into another of said devices of the impregnation reactor (4), cooking reactor (9) or enzymatic hydrolysis reactor (20).;

2. A method according to the preceding claim, characterized in that washing of the or at least one of the feeding devices (6; 11) is performed by circulating a washing fluid (7; 12) between a washing inlet and a washing outlet of said feeding device, the the washing outlet preferably also being the solid-liquid residue extraction outlet.

3. A process according to any one of the preceding claims, characterized in that at least a portion of the liquid residue (31;41) is reintroduced into the same feeding device, or into one of said feeding devices for the impregnation reactors (4), cooking reactors (9) or enzymatic hydrolysis reactors (20), or as a supplement for the impregnation liquor (4).

4. A method according to any one of the preceding claims, characterized in that the or at least one of the feeding devices (6;11) of the impregnation reactor (9) and the cooking reactor (14) creates a pressure increase between the biomass inlet and the biomass outlet of said device, this pressure increase generating a compression of the biomass leading to the extraction of the solid-liquid residue (8;13).

5. A method according to any one of the preceding claims, characterized in that the or at least one of the feeding devices (6;11) of the impregnation reactor (9) and of the cooking reactor (14) is a feed screw, in particular at least in a conical part, comprising a shroud provided with a cage having openings which allow the extraction of the solid-liquid residue (8;13) from the biomass and optionally the circulation of a washing fluid (7;12).

6. A method according to any one of the preceding claims, characterized in that said solid-liquid residue (8;13) is separated into a solid residue (32;42) and a liquid residue (31;41) by at least one separation device (30;40) selected from a centrifugation device, a draining or pressing device, a screen.

7. A process according to any one of the preceding claims, characterized in that it comprises at least one step of treating biomass by fermentation, said step being subsequent to or concurrent with the enzymatic hydrolysis step, in a fermentation reactor (22) equipped with its feeding device.

8. A process according to the preceding claim, characterized in that it comprises at least one biomass treatment step aimed at separating solvents or alcohols, said step being subsequent to the fermentation step and being carried out in a separation reactor (22) equipped with its feeding device.

9. A method according to any one of the preceding claims, said method comprising the following steps: - a) Preparation of an impregnation liquor (4) containing a chemical catalyst (2) for impregnating biomass (5), the catalyst being selected from an acid catalyst, a basic catalyst, and an oxidizing catalyst, and preferably an acid catalyst, in a preparation zone (3); - b) Introduction of the biomass (5) into an impregnation reactor (9) using a first feeding device (6), said first feeding device being washed by circulating a first washing fluid (7) between a washing inlet and a washing outlet of said device (6); - c) Introduction of the liquor into the impregnation reactor (9) through a first liquor inlet (4) of the reactor.- d) Transfer of the impregnated and then drained biomass (10) from an outlet of the impregnation reactor to an inlet of a pretreatment reactor (14) by cooking by at least one second feeding device (11), said second feeding device being washed by circulation of a second washing fluid (12) between a washing inlet and a washing outlet of said feeding device, - e) Pretreatment of said biomass (10) in said reactor by cooking or steam explosion (14), - f) Extraction from the biomass of a solid-liquid residue (8; 13) passing through at least one of the two feeding devices (6; 11) of the impregnation reactor (9) and the cooking reactor (14), then separation of said residue(s) from each of the solid-liquid residues into a solid residue (32; 42) and a liquid residue (31; 41),with reintroduction of at least part of the solid residue as biomass supplement in at least one of the feeding devices (6; 11) of the impregnation reactor (9) and the cooking reactor (14), and reintroduction of at least part of the liquid residue (31; 41) as washing fluid supplement in at least one of the feeding devices (6; 11) of the impregnation reactor (9) and the cooking reactor (14) or as supplement for the impregnation liquor in the liquor preparation zone (3) or in the impregnation reactor (9).

10. Use of the process according to any one of the preceding claims for the treatment of lignocellulosic biomass (5), such as wood, straw, agricultural residues, and all dedicated energy crops, in particular annual or perennial plants such as miscanthus, with a view to producing sugars, biofuels or bio-based molecules.

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