Injection of hydrogen produced by water electrolysis in a unit for producing biofuels

Abstract

The invention describes a method in which the steps of pretreatment, gasification, Fischer-Tropsch synthesis, water electrolysis and conversion of carbon dioxide to hydrogen (RWGS reaction) are combined to optimal effect, making it possible to achieve improved production yields and better energy and economic performance (energy efficiency, production cost) while complying with environmental constraints, such as greenhouse gas emissions, to which increasingly lower thresholds apply.

Description

[0001] INJECTION OF HYDROGEN PRODUCED BY WATER ELECTROLYSIS ONTO A BIOFUEL PRODUCTION UNIT OBTAINED

[0002] technical field

[0003] The invention is in the field of advanced biofuel production, i.e. the use of resources as defined in Annex IX A of the European Red II Directive.

[0004] Previous technique

[0005] Patent application WO2014 / 068253A1 implements a biofuel production chain from lignocellulosic biomass.

[0006] In this reference scheme illustrated by Figure 1, biofuel production is carried out in several stages:

[0007] - Step A of biomass pretreatment (1) which is preferably carried out by a drying and torrefaction step. Other processes such as pyrolysis can be implemented.

[0008] - Step C involves gasifying the pretreated biomass (2) to produce a synthesis gas (3), preferably using a flow-through / entrained bed gasifier with a cooled wall. Other technologies such as fluidized beds, fixed beds, and plasma can be used. Partial oxidation of the biomass is preferably carried out using a pure oxygen stream (11). The use of high-purity oxygen limits the amount of inert compounds, such as nitrogen, when using air. This oxygen is produced by an air separation unit B.

[0009] - Step D' of adjusting the H2 / CO ratio of the synthesis gas (3) is carried out by the water-gas-shift reaction according to Anglo-Saxon terminology. This step allows the H2 / CO ratio to be adjusted for the downstream synthetic hydrocarbon conversion process.

[0010] - Step D of decarbonation and purification of the syngas (4) to eliminate inert CO2 (12) and capture harmful elements for the catalysts used in downstream processes to produce a purified syngas (5),

[0011] - Stages E and F of synthetic hydrocarbon production in which purified syngas (5) is sent to a Fischer-Tropsch synthesis process (E) followed by a hydroconversion process (F) of the produced effluents (6) for the production of biofuels (7). The syngas could also be used by catalytic / biological conversion for the production of methanol, DME, ethanol, alcohols, oxo synthesis, SNG, etc. A portion of the gaseous fraction of the Fischer-Tropsch synthesis products can be combined with the feedstock at the gasification stage, with the remaining fraction being used as fuel.

[0012] This patent application describes the possible injection of hydrogen at any point in the process chain. The injected hydrogen is produced by any means known to those skilled in the art, without any particular distinction or integration between the hydrogen production process and the processes in the biofuel production chain.

[0013] One drawback of this implementation is that two steps have a particularly significant impact on performance:

[0014] - The gasification stage where part of the feedstock is burned to produce the necessary energy. Carbon dioxide is formed.

[0015] - The H2 / CO ratio adjustment step. This step, carried out by water-gas-shift, consumes water and carbon monoxide and generates hydrogen and carbon dioxide.

[0016] A loss of yield is observed during the transformation of lignocellulosic biomass into synthetic hydrocarbons.

[0017] US patent 9562196 highlights an adjustment of the hydrogen content at the inlet of the Fischer-Tropsch unit by reforming the naphtha produced by the Fischer-Tropsch synthesis. This option reduces the quantity of finished products produced by consuming the naphtha produced.

[0018] Patent WO 2015 / 101717 describes the use of external hydrogen to adjust the H2 / CO ratio of a synthesis gas produced by the gasification of a carbonaceous feedstock, particularly biomass. This patent claims to adjust synthesis gas production based on the amount of external hydrogen in order to maintain a constant synthetic fuel production.

[0019] The document entitled "A look into the role of e-fuels in the transport system in Europe (2030-2050)" (Concawe Review Volume 28, Number 1, October 2019) presents the production pathway for decarbonized fuels known as "e-fuels" or "power-to-liquids." These fuels are produced from carbon dioxide, captured from the air or from combustion fumes, which is transformed in the presence of hydrogen by the reverse water-gas shift reaction into carbon monoxide and water. The hydrogen is produced by electrolysis from water. The carbon contained in the carbon dioxide captured from the fumes is not necessarily of biogenic origin. Finally, the carbon dioxide present in the air is so dilute that its extraction requires a significant amount of energy.The document "Flexible hybrid process for combined production of heat, power and renewable feedstock for refineries" (2020, Joint Workshop of Task 39 and Task 44, IEA Bioenergy Technology Collaboration Programme) describes a combination of a lignocellulosic biomass conversion unit and water electrolysis. The lignocellulosic biomass conversion is carried out in a fixed-bed gasifier after a drying stage. The quality of the resulting syngas necessitates a reforming stage in the presence of a catalyst, carbon dioxide, and oxygen to convert unconverted particles into hydrogen and carbon monoxide. The oxygen produced by electrolysis is sent to the gasifier and the reforming stage. The hydrogen is sent to the Fischer-Tropsch synthesis stage. The recovered CO2 is reinjected into the gasification and reforming stages.Part of the tail-gas is used to produce steam which is also sent to the gasification stage.

[0020] In the article "Improving carbon efficiency and profitability of the biomass to liquid process with hydrogen from renewable power" (2018, Fuel 234, 1431-1451, Hillestad et al.), the authors present an integration between a biomass-based synthetic hydrocarbon production unit and water electrolysis. The diagram highlights a step in the conversion of the CO2 produced to the gasification stage by a "Reverse Water Gas Shift" unit. This unit consumes some of the hydrogen produced in a solid oxide electrolysis unit that transforms superheated steam at 850°C. Furthermore, the entire output of the gasification section, containing CO2 and water vapor, is admitted into the "Reverse Water Gas Shift" section, which limits CO2 conversion and requires a significant investment for reactor construction.

[0021] French patent application FR 3029533 A1 describes a thermochemical conversion process for carbonaceous materials in which hydrogen is added downstream of the synthesis gas purification stage, or a mixture of synthesis gas and hydrogen undergoes a reverse gas scavenging (RWGS) step. In this document, all of the synthesis gas is treated in the RWGS step.

[0022] Patent application W02022 / 079407 describes a process for synthesizing hydrocarbons from a synthesis gas in which at least a portion of the carbon dioxide and a portion of the hydrogen produced by electrolysis feed a reverse water-gas shift unit to produce a carbon monoxide stream. In the example shown, the volumetric flow rate of hydrogen required for the reaction is more than six times the flow rate of CO2 processed. This results in a significant energy cost for heating the incoming gas streams to the reaction temperature. Furthermore, the electrolysis process produces an excess of oxygen relative to the needs of the entire chain.

[0023] One of the problems encountered by the person skilled in the art in the field of invention concerns the improvement of production yields and the energy and economic performance of the production chain on an industrial scale while respecting increasingly severe environmental constraints.

[0024] In the case of the present invention, the applicant proposes a new process which presents an optimal integration of the steps of pretreatment, gasification, Fischer-Tropsch synthesis, water electrolysis and conversion of carbon dioxide to hydrogen (RWGS) making it possible to achieve improved production yields and better energy and economic performance (energy efficiency, production cost, etc.) while respecting environmental constraints such as greenhouse gas emissions imposed at increasingly lower thresholds.

[0025] Summary of the invention

[0026] In particular, the present invention relates to a process for converting a feed comprising at least a biomass fraction into hydrocarbons, and producing carbon dioxide that can be used as a by-product, said process comprising at least the following steps:

[0027] - possibly a step a) of pre-processing the load,

[0028] - a step b) of electrolysis of water into oxygen and hydrogen allowing the obtaining of a flow of hydrogen, and a flow of oxygen, in which the water is obtained, at least in part, from a step e) of Fischer-Tropsch synthesis,

[0029] - a step c) of gasification of the feed possibly pre-treated in step a), in the presence of all or part of the oxygen flow from step b) of water electrolysis so as to obtain a gaseous effluent comprising a synthesis gas,

[0030] - a step d) of removing acidic compounds and impurities from the gaseous effluent comprising a synthesis gas from step c) mixed with a gaseous effluent from step g) after condensation of water vapor, so as to obtain a gaseous effluent comprising a purified synthesis gas and a carbon dioxide stream feeding at least in part a step (g) of conversion of carbon dioxide to hydrogen (RWGS),

[0031] - a Fischer-Tropsch synthesis step e) of the gaseous effluent comprising a purified synthesis gas from step d) and possibly part of the hydrogen stream from step b) of water electrolysis so as to produce a stream comprising synthetic liquid hydrocarbons, water and at least one gaseous effluent,

[0032] - a step (f) of hydroconversion of at least a portion of the stream comprising liquid hydrocarbons from step (e) to produce at least one liquid biofuel cut and at least one gaseous effluent

[0033] - a carbon dioxide to hydrogen conversion step (g) to produce at least one gaseous effluent comprising carbon monoxide CO and water vapor, wherein the feed entering said step g) comprising at least a portion of the hydrogen stream from step b) and a carbon dioxide stream, has at least one of the following two characteristics:

[0034] A / at least a portion of the hydrogen stream from step b) is mixed with the carbon dioxide stream from step (d) and optionally with a carbon dioxide stream from one or more combustion units of the gaseous effluents from steps e) and / or f) and / or optionally a), and optionally with a carbon dioxide stream external to the process, such that the molar ratio of hydrogen to carbon dioxide H2 / CO2 at the inlet of the reactor in step g) of carbon dioxide to hydrogen conversion is adjusted between 1.8 and 3, the molar ratio of hydrogen to carbon monoxide H2 / CO at the inlet of step e) of Fischer-Tropsch synthesis is adjusted by another portion of the hydrogen stream from step b), and / or

[0035] B / The carbon dioxide stream from step (d) is mixed with the hydrogen stream from step b) and a carbon dioxide stream from one or more combustion units of the gaseous effluents from steps e) and / or f) and / or possibly a), and possibly with a carbon dioxide stream external to the process, the mixture of said carbon dioxide streams and the hydrogen stream from step b) feeding the carbon dioxide to hydrogen conversion step (g) (RWGS).

[0036] The said pretreatment steps a), hydroconversion steps f) and carbon dioxide to hydrogen conversion steps g) advantageously comprise one or more combustion unit(s) that can be supplied with at least some of the oxygen from the water electrolysis step b) or with an air stream possibly enriched with oxygen from the step (b).

[0037] The present invention offers numerous advantages over the prior art; in particular, the proposed invention allows:

[0038] - To improve the carbon yield of said process, in particular by implementing the carbon dioxide to hydrogen conversion reaction (RWGS) optimized by controlling the H2 / CO2 ratio and / or by recycling carbon dioxide streams from one or more secondary combustion units of gaseous effluents from steps a) and / or e) and / or f) of the process.

[0039] - To improve the yield of the hydrocarbon chain.

[0040] - To reduce the operating costs of said process by using oxygen produced by step b) of electrolysis for gasification and possibly for secondary combustion units,

[0041] - To limit the capacity and therefore the investment in the air separation and carbon monoxide to water conversion unit (water gas shift according to Anglo-Saxon terminology) depending on the amount of electrolytic hydrogen supplied to the system,

[0042] - To reduce the energy consumption required to reach the optimal temperature conditions for the carbon dioxide to hydrogen conversion reaction (Reverse Water Gas Shift, according to Anglo-Saxon terminology) and maximize the carbon yield achievable by implementing this step in the chain,

[0043] - To produce a fuel compatible with the objective of reducing carbon dioxide emissions from advanced biofuels,

[0044] - To reduce the amount of feedstock required for a targeted biofuel production capacity.

[0045] - And to reduce the water consumption required in step b) of electrolysis by recycling the aqueous effluents produced at any of the steps of said process, including for example the water produced in the combustion units of the gaseous effluents.

[0046] In particular, an advantage of the present invention is to provide a process for the production of synthetic hydrocarbons by the indirect thermochemical conversion of lignocellulosic biomass allowing for an improvement in material yield and an optimization of the scheme by the implementation of a step g) of conversion of carbon dioxide to hydrogen by the Reverse Water Gas Shift reaction according to the Anglo-Saxon terminology, with a flow of hydrogen generated from a flow of water produced by electrolysis (step b).

[0047] Another advantage of the present invention is that it provides a method for utilizing the carbon dioxide (CO2) produced in the various stages of the process according to the invention, specifically in step (g) of carbon dioxide conversion to hydrogen via the reverse water-gas shift (RWGS) reaction. This benefit helps to limit CO2 emissions and maximize the carbon efficiency of the entire process.

[0048] Another advantage of the present invention lies in the implementation of said step b) of water electrolysis in the process chain according to the invention, which has the following advantages: - Use of decarbonized hydrogen (necessity of using decarbonized electricity) which makes it possible to obtain a fuel whose reduction in greenhouse gas emissions is eligible under the European Red II directive,

[0049] - Adjustment of the H2 / CO molar ratio at the inlet of step e) of the Fischer-Tropsch synthesis by injecting hydrogen produced in said step b) of water electrolysis. This adjustment allows the carbon monoxide (CO) to be retained in the synthesis gas and increases the material yield and / or reduces the quantity of input resources. The injection of hydrogen produced in said step b) of water electrolysis makes it possible to eliminate all or part of the carbon monoxide-to-water conversion unit (water gas shift according to Anglo-Saxon terminology) present in the prior art process and therefore eliminate this investment item.

[0050] - Oxygen generation in said step b) of water electrolysis: the oxygen produced can be used in the process according to characteristic B and possibly according to characteristic A as a replacement for the oxygen produced by the air separation unit, thus limiting the investment in the unit. The excess oxygen produced in step b) can advantageously be used:

[0051] - For the oxidation of hydrogen sulfide H2S contained in the effluents of step (d)

[0052] - For the combustion of gaseous effluents from the process chain

[0053] - For the combustion of the pretreatment gases produced in step a).

[0054] Another advantage of the invention lies in the use of water produced in any of the process steps, by recycling it in step b) of water electrolysis, and in particular water from step e) of Fischer-Tropsch synthesis, water produced by the pretreatment step a) of wet biomass, water from the condensates of combustion fumes from steps (a) and / or (f), and water produced in step g) of carbon dioxide-to-hydrogen conversion (RWGS). This reduces the process water consumption and consequently the operating costs.

[0055] Description of the figures

[0056] Figure 1 shows the prior art reference diagram WO2014 / 068253A1 and the associated comparative example 1

[0057] Figure 2 represents the different stages of the production process according to the invention.

[0058] Figure 3 shows the main flows in comparative example 2 according to prior art W02022 / 079407A1. Figure 4 shows the main flows in example 3 illustrating feature A according to the invention (H2 / CO2 = 2 at the inlet of block G).

[0059] Figure 5 represents the main flows in example 4 according to characteristic B according to the invention (H2 / CO2 = 6.5 at the RWGS inlet) with recycling of CO2 from combustion to block G.

[0060] Figure 6 represents the main flows in examples 5 and 6 illustrating the characteristics A + B according to the invention (H2 / CO2 = 2 at the RWGS inlet) with recycling of 002 from the combustion units of stages A and F to block G.

[0061] In the sense of the present invention, the different embodiments presented can be used alone or in combination with each other, without limitation of combination.

[0062] In the context of the present invention, different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in the context of the present invention, a preferred range of pressure values ​​can be combined with a more preferred range of temperature values.

[0063] In the following text, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included within the described range of values. If this were not the case and the limit values ​​were not included within the described range, this clarification will be provided by the present invention.

[0064] In this description, the expression "greater than..." is understood as strictly greater than, and symbolized by the sign ">", and the expression "less than" as strictly less than, and symbolized by the sign ">". Description of embodiments

[0065] The present invention relates to a method for converting a feed comprising at least a biomass fraction into renewable hydrocarbons.

[0066] Charges

[0067] The biomass fraction can include any type of biomass, preferably solid biomass, and in particular lignocellulosic biomass. Non-limiting examples of biomass types include, for example, raw materials from Annex IXA of the European Renewable Energy Directive (red 2), agricultural residues (in particular straw, corn cobs), forestry or paper mill residues, forestry products, sawmill residues, waste wood, dedicated crops, short-rotation coppice or very short-rotation coppice.

[0068] The feed converted in the process according to the invention may further comprise at least a fraction of another feed, preferably at least a fraction of a gaseous, solid, and / or liquid hydrocarbon feed ("co-processing" in Anglo-Saxon terminology). Said hydrocarbon feed fraction is understood within the scope of the present invention to be a feed fraction that may advantageously contain at least coal, petroleum coke (petcoke in Anglo-Saxon terminology), natural gas, petroleum residues, crude oils, topped-off crude oils, deasphalted oils, deasphalting asphalts, derivatives of petroleum conversion processes (such as, for example: FCC HCO / Slurry, coking heavy GO / VGO, residue from visbreaking or similar thermal processes, etc.).), oil sands or their derivatives, shale gas and oil shale or their derivatives, liquid biomass (such as rapeseed oil, palm oil, pyrolysis oil, ...), slurry biomass according to Anglo-Saxon terminology corresponding to a mixture of liquid biomass with a solid hydrocarbon load, solid municipal waste or equivalent containing non-biogenic carbon, hydrocarbon solid waste, organic waste, industrial polymers or domestic plastics.

[0069] According to the process of the invention, said hydrocarbon filler fraction can be a gaseous, solid, liquid hydrocarbon filler fraction or a mixture thereof.

[0070] The feedstock for the process according to the invention can therefore be a feedstock comprising at least a solid biomass fraction, and optionally at least a fraction of another gaseous, solid, or liquid feedstock, alone or in mixtures. Generally, the feedstock used in the process of the invention comprises at least 10%, and preferably at least 20%, preferably at least 50%, preferably at least 70%, and most preferably at least 90%, of a biomass fraction.

[0071] The different stages of the process according to the invention are described below.

[0072] Step a) optional

[0073] The process may advantageously include a step a) of pretreatment of the feed.

[0074] Step a) of pretreatment of the feed enables the production of a feed comprising pretreated biomass and at least one gaseous effluent.

[0075] Preferably, the pretreatment step includes at least one of the following operations: drying (a1), roasting (a2), gas combustion (a3), or grinding (a4). Preferably, pretreatment step (a) includes a drying operation (a1), a roasting operation (a2), a gas combustion operation (a3), and a grinding operation (a4). In this case, pretreatment step (a) of the feed enables the production of a feed comprising roasted biomass and at least one gaseous effluent.

[0076] In an embodiment where the load used is already dry, the pretreatment step includes a roasting operation a2), gas combustion a3) and a grinding operation a4).

[0077] When the hydrocarbon feed fraction is gaseous or liquid, it is advantageously introduced directly into step c) of gasification without being subjected to step a) of pretreatment. a1) Drying operation

[0078] The pretreatment step (a) of the feed may advantageously include a drying operation (a1) of the feed, advantageously carried out at a temperature between 20 and 180°C, preferably between 60 and 160°C, and preferably between 100 and 140°C, for a duration of between 5 and 180 minutes, and preferably between 15 and 60 minutes. At the start of the drying operation (a1), the feed generally has a moisture content of between 15 and 80% by mass. The residual moisture content in the feed at the end of the drying operation is advantageously less than 25% by mass, preferably less than 15% by mass, and more preferably less than 10% by mass. The drying operation may be carried out by any means known to those skilled in the art.

[0079] The energy required for drying is generally supplied by bringing the load into contact with a stream of hot gas. a2) Heat treatment operation

[0080] Step a) of pretreatment of the charge may include a heat treatment operation a2), preferably of the dried charge resulting from the drying operation a1).

[0081] Step a2) of thermal treatment allows the production of a solid effluent and a gaseous effluent called pretreatment gas.

[0082] Advantageously, the heat treatment operation can be a roasting operation.

[0083] The roasting operation (a2) can be carried out in a roasting oven that produces a solid, more friable, roasted biomass feedstock effluent, and consequently requires less energy to be finely ground to obtain a roasted effluent. The roasting operation is advantageously carried out at a temperature between 220 and 350°C, preferably between 250 and 320°C and more preferably between 270 and 300°C for a duration between 5 and 180 minutes, and preferably between 15 and 60 minutes, at an absolute operating pressure preferably between 0.01 and 1.5 MPa, preferably between 0.01 and 1.0 MPa and more preferably between 0.05 and 0.15 MPa. The roasting operation is carried out in an environment where the oxygen content is advantageously less than 10% by volume, preferably less than 8% by volume and preferably less than 3% by volume.

[0084] The heat treatment process has the advantage of reducing the energy cost of operation a3) grinding and results in a dry matter loss of between 5 and 40% by mass, preferably between 10 and 35% by mass. However, this dry matter loss is accompanied by a much smaller loss of calorific value, on the order of 5 to 20%. Therefore, the heat treatment process increases the volumetric energy content of the biomass, that is, its energy per unit volume.

[0085] The energy required for operation a2) of thermal treatment is supplied by the combustion of the pretreatment gas, possibly supplemented by the combustion of auxiliary gas, which may be natural gas or, preferably, some or all of the gaseous effluents from step e) and / or f). a3) Gas combustion section

[0086] The pretreatment step (a) advantageously comprises one or more gas combustion units, preferably for pretreatment gases produced in said step (a) and preferably in the heat treatment operation (a2), in which said gases are burned in a combustion step to produce flue gases containing carbon dioxide. These flue gases can advantageously be used as a hot gas stream to supply the energy required for the drying operation (a1) and the heat treatment operation (a2). If the energy supplied by the combustion of the pretreatment gases is insufficient to meet the thermal requirements of step (a), said combustion step can advantageously be supplemented by the implementation in said step (a) of an auxiliary gas combustion step, which may be natural gas and / or some or all of the gaseous effluents from steps (e) and / or (f).The excess energy contained in the combustion fumes can be used to produce steam at different pressure levels as needed for the various stages of the process.

[0087] In the case where an auxiliary gas combustion step is also implemented in said step a), the combustion steps of the pretreatment gas on the one hand and of the auxiliary gases on the other hand may be carried out in a common combustion unit or in two separate combustion units, each of the units being able to be supplied either with air, or with part of the oxygen flow from step b) or by a mixture of air and oxygen from step b) in any proportions.

[0088] According to a preferred embodiment of the invention, the combustion unit(s) of said pretreatment step a) can be supplied with at least some of the oxygen from the water electrolysis step b).

[0089] In another embodiment, the combustion unit(s) of said pretreatment step a) may be supplied by an airflow optionally enriched in oxygen from step (b).

[0090] In these last two embodiments, the combustion unit(s) advantageously include a flue gas cooling stage that separates carbon dioxide from water vapor by condensation. In the case of combustion using air, the combustion section may be supplemented by a process for separating carbon dioxide from nitrogen contained in said flue gases, this separation being carried out by the use of chemical or physical solvents, a mixture of chemical and physical solvents, or any other means known to those skilled in the art.

[0091] According to a preferred embodiment of feature B of the invention, the carbon dioxide stream produced by the combustion unit(s) of said pretreatment step (a) feeds the feed of step (g), mixed with the carbon dioxide stream from step (d) and the hydrogen stream from step (b). In a preferred embodiment, the carbon dioxide stream produced by the combustion of the pretreatment gas from step (a) feeds the feed of step (g), mixed with the carbon dioxide stream from step (d) and the hydrogen stream from step (b).

[0092] More generally, all or part of the carbon dioxide stream produced by the combustion unit(s) of the pretreatment stage can be used as a by-product of the process to supply a transport network, a storage unit or any carbon dioxide recovery facility external to the process.

[0093] Advantageously, the water formed in the combustion unit(s) of step a) of wet biomass pretreatment is partially or totally sent to step b) of electrolysis. Recycling the water formed in step a) to step b) reduces the operating costs of the process according to the invention.

[0094] In one embodiment, the water formed during pretreatment step a) advantageously undergoes a treatment step before being recycled in water electrolysis step b) so as to obtain the required specifications of step b). The treatment step may advantageously consist of removing oxygenated compounds from the water formed during step a).

[0095] More generally, the water produced in any of the process steps, and preferably the water produced in the combustion unit(s) of step a) wet biomass pretreatment and / or the hydroconversion step f), preferably by condensation of the combustion fumes from said combustion units, the water produced in step e) Fischer-Tropsch synthesis, and the water produced in step g) carbon dioxide-to-hydrogen conversion (RWGS), is recycled in step b) water electrolysis. a4) Grinding operation

[0096] Step a) of pretreatment of the feedstock may also advantageously include a grinding operation a4), preferably of the roasted effluent from operation a2).

[0097] The grinding operation a4) can be carried out under conditions allowing a reduction of the feedstock and preferably of the roasted effluent from operation a2) into particles of a size suitable for treatment in an entrained flow gasification unit (step c). At the end of the grinding operation a4), 90% of the feedstock particles preferably have an equivalent diameter of less than 300 microns and 90% of the feedstock particles preferably have an equivalent diameter greater than 1 micron; preferably 90% of the feedstock particles have an equivalent diameter less than 200 microns and 90% of the feedstock particles have an equivalent diameter greater than 5 microns; and more preferably 90% of the feedstock particles have an equivalent diameter less than 100 microns and 90% of the feedstock particles have an equivalent diameter greater than 10 microns.The equivalent diameter, denoted "de", is defined for example according to the following relation: de=V / S with V the volume of the particle.

[0098] S is the surface of the sphere with the same volume as the particle.

[0099] In a particular embodiment, the grinding operation a4) can be carried out in the presence of a second fossil feed or biomass so that it is ground simultaneously in a single mill. When this second feed is fossil, it can be chosen from solid fossil hydrocarbons such as coal or petroleum coke (petcoke). When this second feed is biomass, it can be chosen from the biomass feeds as defined previously. An advantage of carrying out the grinding in the presence of a second feed is that it allows for the efficient grinding and drying of said second feed.

[0100] Preferably, the grinding operation a4) can be carried out in the presence of an additional compound useful for the subsequent gasification step, said compound being chosen from vitrified ashes, sand, limestone, lime or other compounds known to the person skilled in the art taken alone or in mixture.

[0101] Preferably, the mill is chosen so as to optimize the pneumatic transport of the powder obtained at the end of operation a4), minimizing the minimum fluidization velocity (UMF), as well as its own energy consumption.

[0102] Preferably, operation a4) of co-crushing is carried out in a roller mill, universal mill, attrition mill, or any other type of mill known to those skilled in the art.

[0103] Step b) of electrolysis

[0104] According to the invention, the process according to the invention comprises a step b) of electrolysis of water into oxygen and hydrogen allowing the obtaining of a flow of hydrogen, and a flow of oxygen, in which the water is obtained, at least in part or in whole, from a step e) of Fischer-Tropsch synthesis.

[0105] According to one embodiment of the invention, the water is obtained from at least one or more steps of the process producing water and is recycled to supply said step b). According to the invention, the water is advantageously obtained at least in part from step e) of Fischer-Tropsch synthesis, and can also advantageously be obtained from step g) of conversion of CO2 to hydrogen and / or possibly from the condensates of the various combustion fumes from steps a) and / or f) and / or from the gaseous effluent from step a) of pretreatment of biomass and preferably from operation a1) of drying.

[0106] According to the invention, the oxygen flow obtained at the end of step b) is sent in part or in whole to step c) of gasification.

[0107] According to a preferred embodiment of the invention, the oxygen flow obtained at the end of step b) is also sent at least in part to one or more gaseous effluent combustion units included in steps (a) and / or (f) of the process.

[0108] Advantageously, the oxygen produced by the electrolysis of water has a purity of at least 98.5% by weight (on a dry basis). The impurities that may be present in the oxygen produced are water and / or hydrogen.

[0109] According to the invention, all or part of the hydrogen stream obtained at the end of step b) of electrolysis is sent to step g) of conversion of CO2 to hydrogen.

[0110] According to one embodiment of the invention, part of the hydrogen flow obtained from step b) of electrolysis is sent to step e) of Fischer-Tropsch synthesis.

[0111] Another part of the hydrogen stream obtained by electrolysis can advantageously be sent to step f) of hydroconversion of the stream comprising liquid hydrocarbons from the Fischer-Tropsch synthesis step (e).

[0112] Advantageously, the hydrogen stream obtained from electrolysis step b) and sent to Fischer-Tropsch synthesis step e) has a purity of at least 99.8% by weight (on a dry basis). Preferably, the hydrogen sent to step e) contains less than 100 ppm of oxygen and / or water, preferably less than 60 ppm, preferably less than 40 ppm, preferably less than 30 ppm, and preferably less than 15 ppm.

[0113] According to feature A of the invention, the molar ratio of hydrogen to carbon monoxide H2 / CO at the input of step e) of Fischer-Tropsch synthesis is adjusted by another part of the hydrogen flow from step b).

[0114] Advantageously, the molar ratio of hydrogen to carbon monoxide, denoted H2 / CO, of the effluent introduced in step e) of Fischer-Tropsch synthesis is between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5 and most preferably equal to 2.1, the hydrogen advantageously coming partly from step d) of removal of acidic compounds and impurities from the synthesis gas effluent and partly from step b) of water electrolysis.

[0115] According to characteristic B of the invention, the molar ratio between hydrogen and carbon monoxide, denoted H2 / CO of the effluent introduced in step e) of Fischer-Tropsch synthesis is advantageously between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5 and most preferably equal to 2, the hydrogen advantageously coming in part or in whole from step d) of removal of acidic compounds and impurities from the synthesis gas effluent and / or in part or in whole from step b) of electrolysis of water.

[0116] Step b) of water electrolysis can be carried out by any means known to those skilled in the art, for example by alkaline electrolysis, by proton exchange membrane, by anion exchange membrane, or by solid oxide electrolysis.

[0117] One advantage of step b) of water electrolysis is to produce decarbonized hydrogen which can be used to obtain a fuel whose reduction in greenhouse gas emissions is eligible under the European Red III directive.

[0118] Another advantage of recycling water from pretreatment step a) and / or Fischer-Tropsch synthesis step e) and / or CO2 to hydrogen conversion step g) and / or combustion fumes from step f) to electrolysis step b) is to reduce process water consumption and consequently operating costs.

[0119] Another advantage of step b) electrolysis is that all or part of the oxygen produced is used in the process in step c) gasification. This reduces, or even eliminates, the need for an air separation unit, thus limiting investment and operating costs. Furthermore, excess oxygen can be advantageously used for treating SRU / TGTU tail gases (Sulfur Recovery Unit / Tail Gas Treating Unit) and / or for burning fuel gas from the unit and residual gas, and / or for burning pretreatment gases.

[0120] Step c) of gasification

[0121] The process according to the invention includes a step c) of gasification of the feed, optionally pretreated in step a), in the presence of all or part of the oxygen stream from step b) of water electrolysis so as to obtain a gaseous effluent comprising a synthesis gas.

[0122] The gasification step involves a partial oxidation reaction that converts the feedstock into a synthesis gas composed primarily of carbon monoxide and hydrogen. This gasification step is advantageously carried out in the presence of a controlled quantity of oxygen, which is obtained in whole or in part from step b) of electrolysis, in the form of an oxygen stream with a purity of at least 98.5% by weight (on a dry basis). Using this oxygen stream limits the amount of inert compounds, such as nitrogen, when air is used as the oxygen source. This reduces the accumulation of inerts and therefore the problems associated with pressure or velocity losses, thus decreasing the size of the equipment required and further reducing the investment and operating costs of the process.

[0123] Advantageously, the gaseous effluent corresponding to the synthesis gas from step c) of gasification is composed mainly of water (H2O), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (CO2), and may include impurities initially from the biomass fraction and / or the fraction of another feed, in particular hydrocarbon feed.

[0124] According to the invention, the oxygen flow implemented in the gasification step is derived in whole or in part from step b) of water electrolysis.

[0125] Advantageously, an oxygen stream from an air separation step can also be used in step c) of gasification, in addition to the oxygen stream from step b) of water electrolysis.

[0126] In one particular embodiment, the entire oxygen flow introduced in the gasification step c) comes from the water electrolysis step b).

[0127] Step c) of feed gasification is carried out in a fixed-bed gasifier, a fluidized-bed gasifier, or preferably in a high-temperature, cooled-wall, driven-flow gasifier, i.e., at a temperature between 800 and 1800°C, preferably between 1000 and 1600°C, and more preferably between 1200 and 1500°C, and at an absolute pressure advantageously between 2 and 12 MPa, preferably between 2.5 and 6.0 MPa, and more preferably between 3.0 and 5.0 MPa. The high temperature allows for a high carbon conversion rate and therefore reduces the amount of unconverted carbon in the ash produced, thus facilitating its disposal or recovery by reducing the need for recycling to the gasifier.

[0128] The entrained flow gasifier is preferably a gasifier known to those skilled in the art as a cooled-wall entrained flow gasifier. The cooled wall defines the gasification chamber, which is itself located within the gasifier. The water used to cool the wall of the gasification chamber circulates in a coil positioned outside the chamber wall. The water is partially vaporized, thus generating a medium-pressure steam flow. This cooling of the walls allows the formation of a protective ash layer on the inner wall of the gasification chamber. Indeed, the feedstocks introduced into the gasifier contain inorganic compounds, which form ash after gasification. At the gasification temperature, this liquid ash, in the form of droplets, solidifies upon contact with the cooled wall and forms a solid layer that acts as insulation.Thus, the thermal protection of the gasification chamber wall is ensured, on the one hand, by a layer of solidified ash and, on the other hand, by a layer of molten ash in contact with the gas phase, which flows towards the bottom of the gasifier. The combustion chamber wall is therefore highly resistant to high temperatures and significant temperature variations. Furthermore, due to their composition, particularly their high content of alkaline compounds, biomass ash is corrosive to refractory linings. Consequently, gasification technologies using internal refractories for wall protection are difficult to operate because of their rapid deterioration, necessitating frequent replacement. In addition, refractories are very sensitive to thermal shock, which destroys this protective layer through fracturing.

[0129] In a cooled-wall entrained-flow gasifier, at least two burners, and preferably four or more depending on the gasifier's capacity, are arranged in the cooled-walled gasification chamber, which operates at a temperature sufficient to melt the ash in the feedstock. Furthermore, the feedstocks introduced into the gasifier can have very different properties. For example, the lower heating value (LHV) of biomass is lower than that of petcoke, the ash content of biomass can be much lower than that of coal, and the ash melting point can vary significantly from one biomass to another. Thus, the ash melting point can vary depending on the composition of the feedstock introduced into the gasification chamber.Similarly, the minimum gasification temperature to be above the melting point of the ash can be adjusted by playing with the nature of the feeds, which have different properties, and the proportions of the different constituents (other biomass, other hydrocarbon feed, ...) and / or by injecting fluxing agent (for example limestone) with the feed.

[0130] In a preferred embodiment of the invention, the syngas produced in the gasification chamber exits it concurrently with the liquid ash flowing to the bottom of the gasifier. This concurrent configuration has the advantage, compared to a configuration where the syngas is discharged from the gasification chamber upwards while the liquid ash flows downwards, of avoiding the risk of blockages in the liquid ash discharge line. Indeed, liquid ash flowing alone in the line can, depending on its viscosity, flow with difficulty and / or partially solidify, partially or completely obstructing the discharge line and leading to a shutdown of the installation for maintenance. These phenomena can occur particularly during transient phases of temperature increases or decreases, or during adjustments related to a change in the nature of the feedstock.The configuration according to the invention has the advantage that the gas flowing in co-current with the liquid ash in the discharge pipe of the gasification chamber facilitates the flow of this ash towards the bottom of the gasifier and avoids the risk of blockages even in the transient phases.

[0131] In a preferred embodiment of the invention, the syngas and liquid ash pass through an intensive liquid quench zone in contact with at least a water film as described in patent application DE102007044726. This quench zone is positioned below the gasification chamber and separates a hot, dry zone at the top from a cooler, wetter zone at the bottom. The hot, dry zone below the gasification chamber is characterized by the presence of syngas and liquid ash flowing to the bottom of the gasifier. The cooler, wetter zone is located below the hot, dry zone and is characterized by the presence of water-saturated syngas, solidified ash, and liquid water. The temperature of the syngas exiting the cold, wet zone corresponds to the thermodynamic equilibrium temperature between the gas and liquid phases at the gasifier's operating pressure.

[0132] This quench configuration allows for a significant reduction of the fine, sticky ash particles carried along during syngas scrubbing, thus minimizing the risk of fouling in downstream piping and units. Furthermore, the high temperature in the gasification chamber allows the molten ash to flow easily down its wall before falling into the quench zone. After passing through the cold, humid unit, the cooled ash settles at the bottom of the water-filled gasifier. Upon contact with the water, the molten ash is immediately cooled and vitrified into dense particles. These particles are then extracted from the gasifier as a mixture of water and solid ash (or slurry) by depressurization. The majority of the mineral compounds in the feedstock form the molten ash.This configuration allows for the advantageous encapsulation of hazardous products such as heavy metals within the vitrified ash. The vitrification process makes this ash highly stable and impervious to leaching.

[0133] In an alternative version of the invention, the produced syngas exits the gasification chamber from the top, while the molten ash flows down the wall counter-currently to the bottom of the water-filled gasifier. Upon contact with the water, the molten ash solidifies rapidly, forming small particles. These particles are then extracted from the gasifier as a slurry (a mixture of water and solid ash) by depressurization. Since most of the mineral compounds contained in the feedstock form the molten ash, this configuration advantageously allows for the encapsulation of hazardous materials such as heavy metals within the vitrified ash. The vitrification process renders this ash highly stable and impermeable to leaching.The syngas exiting the gasification chamber from the top, along with the finest molten ash particles carried with it, is cooled by a stream of chilled, particle-free syngas. This cooling process solidifies the molten ash into non-sticky solid particles. After this initial cooling stage, the syngas is directed to a heat exchanger to produce steam. To remove the remaining fine solid particles, the syngas then passes through a gas-solid phase separation section using any technique known to those skilled in the art, such as cartridge filters. A portion of this cooled, particle-free syngas is recycled back to the gasifier outlet to cool the syngas exiting the top of the gasifier.

[0134] Step d) Removal of acidic compounds and impurities from the synthesis gas

[0135] The process according to the invention includes a step d) of removing acidic compounds and impurities from the gaseous effluent comprising a synthesis gas from the gasification step c) so as to obtain a gaseous effluent comprising a purified synthesis gas and a carbon dioxide stream.

[0136] The synthesis gas produced in step c) of gasification is composed mainly of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), and water (H2O), and may include impurities initially originating from the biomass fraction and / or another feed fraction, particularly hydrocarbon feed. These impurities are essentially metals, especially alkali metals (Na, K), sulfur compounds, as well as chlorinated and nitrogen compounds. In particular, the halogenated compounds initially present in the feed according to the invention may reach levels of at least 250 ppm by mass in the crude hydrocarbon feed fraction (before drying), and at least 10,000 ppm by mass in the case of the crude biomass fraction (before drying).

[0137] Preferably, step d) includes, preferably consists of, steps d1) and / or d2), and / or d3), d4), d5) and / or d6).

[0138] Step d1) of washing the syngas with water

[0139] Preferably, step d) includes a water scrubbing step d1) to remove traces of solids from the synthesis gas as well as some of the water-soluble gaseous compounds. This operation can be carried out by any type of technique known to those skilled in the art, including a water scrubber with a venturi effect, a scrubber column with all types of internals, etc.

[0140] Preferably, at the outlet of the water washing step, the syngas is subjected to a step d2) of catalytic hydrolysis of the COS and HCN compounds contained in the effluent from step d1) into H2S and NH3.

[0141] Step d2) of catalytic hydrolysis of COS and HCN compounds

[0142] Preferably, step d) includes a step d2) of catalytic hydrolysis of the COS and HCN compounds of the gaseous effluent including the synthesis gas from step d1).

[0143] The effluent from step d1) is subjected to step d2) of catalytic hydrolysis of COS and HCN to H2S and NH3, resulting in a purified effluent. This step eliminates COS and HCN, which are poisons for the Fischer-Tropsch synthesis catalyst. According to the invention, step d2) of catalytic hydrolysis of carbon oxysulfide (COS) and hydrogen cyanide (HCN) is advantageously carried out in the presence of a catalyst containing a platinum-based compound, or an oxide of an element selected from the group including titanium, zirconium, aluminum, chromium, zinc, or a mixture thereof.

[0144] Preferably, the hydrolysis catalyst is a titanium oxide-based catalyst. The catalyst used may also contain at least alkali metals, alkaline earth metals, and / or rare earth elements, derived, for example, from precursors such as potassium hydroxide, zirconium oxide, sodium or barium carbonate, sodium or barium bicarbonate, calcium sulfate, sodium or barium acetate, and sodium or barium oxalate. The hydrolysis step is advantageously carried out at a temperature between 100 and 400°C, preferably between 200 and 350°C.

[0145] Advantageously, the effluent from the hydrolysis unit of step d2) contains less than 25 ppm by volume of COS and less than 5 ppm by volume of HCN, preferably less than 10 ppm by volume of COS and less than 1 ppm by volume of HCN, and more preferably less than 5 ppm by volume of COS and less than 0.1 ppm by volume of HCN.

[0146] In a variant of the process according to the invention, the effluent from the carbon monoxide to steam conversion step (d3) is at least partially sent mixed with said complementary portion to the catalytic hydrolysis step of COS and HCN to H2S and NH3 (step d4). Advantageously, the effluent from the carbon monoxide to steam conversion step (d3) is sent mixed with said complementary portion to the catalytic hydrolysis step (step d4) after cooling to a temperature preferably between 100 and 400°C, preferably between 200 and 350°C.

[0147] Step d3) washing with water

[0148] Preferably, step d) includes a step d3) of washing with water the effluent obtained at the end of step d2). Step d3) allows the removal of impurities such as NH3 and HCl which are soluble in water and particularly harmful to the operation of step d4) of acid gas removal.

[0149] In a variant of the process according to the invention, the effluent obtained at the end of step d2) may be pre-treated with a heavy metal removal step on at least one suitable guard bed. This removal step substantially removes heavy metals, such as lead, arsenic, and mercury, before the effluent is treated in step d3) of water scrubbing and, more specifically, before step d4) of acid gas removal. Fixed-bed reactor technology is advantageously preferred for capturing the heavy metals contained in the synthesis gas using capture media known to those skilled in the art. Advantageously, the removal step is carried out on at least one or more guard beds in the presence of one or more capture media containing one or more active phases.Advantageously, said active phases contain at least one sulfur compound, such as, for example, supported elemental sulfur, and / or a metallic sulfide such as copper and / or zinc sulfide, and at least one precious metal such as silver, gold, or palladium, and / or a silver-exchanged zeolite, and / or oxides of transition metals such as, for example, copper or nickel oxides. Advantageously, said active phase(s) are supported, for example, on alumina, silica, silica-alumina, or activated carbon.

[0150] Advantageously, passing the effluent through at least one guard bed of the removal stage makes it possible to meet the required specifications at the inlet of the acid gas removal stage d4 (stage d4), as well as the required specifications for the Fischer-Tropsch synthesis unit of stage e).

[0151] In a second variant according to the invention, the heavy metal removal step is implemented between step d3) of water washing and step d4) of acid gas removal.

[0152] In a third embodiment of the invention, the heavy metal removal step is carried out after step d4) of acid gas removal, where the solvent used in step d4) is a chemical solvent derived from an alkanolamine, known to those skilled in the art to be less sensitive than physical solvents to the presence of heavy metals. At the outlet of the heavy metal removal step, the effluent generally has a concentration of less than 1 ppb by volume of lead, arsenic, and mercury, preferably less than 0.5 ppb by volume, more preferably less than 0.1 ppb by volume, and even more preferably less than 0.01 ppb by volume of lead, arsenic, and mercury.

[0153] Step d4) of acid gas separation

[0154] Step d4) is dedicated to separating acidic gases such as sulfur compounds (H2S) or CO2 remaining in the gaseous effluent including the syngas from step d3), as well as to separating the CO2 remaining in the gaseous effluent from step (g). The gaseous effluent including the syngas from step d3 and the gaseous effluent from step g) can advantageously feed the same separation unit after a recombination step d5) located upstream of step d4), or preferably two separate separation units. Using a separate CO2 separation unit for the effluent from step g) can have the advantage of operating the two units independently, maintaining a smaller size for the unit separating the CO2 and the sulfur compounds contained in the effluent from step d3).

[0155] Step d4) is carried out by using chemical or physical solvents, a mixture of chemical and physical solvents, or any other means known to those skilled in the art. The chemical solvent may be, for example, a primary, secondary, or tertiary amine derived from an alkanolamine, such as monoethanolamine (MEA), diethanolamine (DEA), or methyldiethanolamine (MDEA), or a mixture of several amines. The physical solvent may be, for example, based on mixtures of polyethylene glycol (PEG) dialkyl ethers, such as PEG diethyl or dibutyl ethers, or methanol.

[0156] The acid gas removal step is, for example, carried out using an acid gas absorption column with the chemical or physical solvent employed, followed by a solvent regeneration step to reduce solvent consumption in the unit. This regeneration step can advantageously be performed in two stages to remove, on the one hand, a gas stream rich in CO2 and, on the other hand, a gas stream rich in H2S.The said CO2-rich gas stream from the regeneration step of the acid gas separation unit, fed at least in part by the effluent from step d3), contains significant quantities of H2S, COS and possibly traces of solvent which must be removed by any means known to those skilled in the art, for example on at least one guard bed based on zinc oxide ZnO, Cu / ZnO, activated carbon and enables the required specifications in terms of impurities to be met in the carbon dioxide stream introduced in step g) of CO2 to hydrogen conversion.

[0157] More generally, all or part of the carbon dioxide stream produced by step d4) can be used as a by-product of the process to supply a transport network, a storage unit or any carbon dioxide recovery facility external to the process.

[0158] Step d5) of recombination

[0159] In the case where the separation of CO2 from the gaseous effluents from step g) and step d3) is carried out in two separate units, the synthesis gases comprising H2 and CO from said separation steps are recombined at step d5) upstream of step d6).

[0160] In the opposite case illustrated in the following examples, the gaseous effluent from step g) is recombined with the gaseous effluent from step d3) at step d5) upstream of the common separation step d4).

[0161] Final purification step d6)

[0162] Preferably, step d) includes a final purification step d6) to obtain a gaseous effluent containing purified syngas. This is because the cobalt-based catalyst used in step e) of the Fischer-Tropsch synthesis is highly sensitive to impurities present in the syngas, which are therefore only tolerated in quantities on the order of ppb (parts per billion). At the outlet of step d4) or d5), the syngas may still contain impurities at concentrations of approximately 100 ppb by volume of H2S and COS.

[0163] Advantageously, the final purification step d6) is carried out on at least one guard bed and can be implemented to completely adsorb the last traces of impurities remaining in the gaseous effluent comprising the synthesis gas, such as halogenated compounds, H2S, COS, HCN and NH3. The final purification step d6) is carried out by any means known to those skilled in the art, for example on at least one guard bed based on zinc oxide ZnO, Cu / ZnO, activated carbon, and makes it possible to achieve the required specifications in terms of impurities in the synthesis gas implemented in the Fischer-Tropsch synthesis step e).

[0164] Advantageously, at the outlet of step d6), the gaseous effluent comprising purified synthesis gas has a sulfur content of less than 100 ppb by volume, preferably less than 50 ppb by volume, more preferably less than 10 ppb by volume; an HCN content of less than 100 ppb by volume, preferably less than 50 ppb by volume, more preferably less than 10 ppb by volume and an NH3 content of less than 100 ppm by volume, preferably less than 10 ppm by volume, more preferably less than 1 ppm by volume.

[0165] Preferably, step d) includes, preferably consists of, steps d1) and / or d2) and / or d3), d4), d5) and / or d6)

[0166] Step e) of the Fischer-Tropsch synthesis catalytic reaction

[0167] The process according to the invention includes a step e) of Fischer-Tropsch synthesis of the gaseous effluent comprising a purified synthesis gas comprising carbon monoxide (CO) and hydrogen from step d), and preferably from step d6) of final purification, and optionally of a portion of the hydrogen stream from step b) of water electrolysis so as to produce a stream comprising synthetic liquid hydrocarbons and at least one gaseous effluent.

[0168] According to the invention, at least a portion of the hydrogen from step b) of water electrolysis is advantageously recombined with the purified synthesis gas from step d) and preferably d6) to obtain an optimal H2 / CO molar ratio for the Fischer-Tropsch reaction so as to produce a stream comprising synthetic liquid hydrocarbons and at least one gaseous effluent.

[0169] According to variant A of the invention, the molar ratio between hydrogen and carbon monoxide H2 / CO at the inlet of step e) of Fischer-Tropsch synthesis is adjusted by sending into said step e) a part of the hydrogen flux from step b).

[0170] According to variant B of the invention, the molar ratio between hydrogen and carbon monoxide H2 / CO at the inlet of step e) of Fischer-Tropsch synthesis can advantageously be adjusted by sending into said step e) a part of the hydrogen flow from step b).

[0171] According to another particular embodiment of variant B of the invention, the H2 / CO molar ratio in the purified synthesis gas from step d) and preferably from d6) is adjusted to its optimal value for the Fischer-Tropsch reaction by regulating the hydrogen flow from step b) of water electrolysis which feeds step g) of CO2 conversion to hydrogen, without sending into said step e) a part of the hydrogen flow from step b).

[0172] Advantageously, step e) of the Fischer-Tropsch synthesis is carried out with a molar ratio between hydrogen and carbon monoxide, denoted H2 / CO, of between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5 and most preferably equal to 2.1.

[0173] The gasification step c) of the feed according to the invention as implemented in the present invention can lead to the production of hydrogen and carbon monoxide in a non-optimal H2 / CO molar ratio for the Fischer-Tropsch reaction, particularly when the catalyst used is a cobalt-based catalyst which advantageously requires an optimal H2 / CO molar ratio of about 2 to be directed towards the production of middle distillates.

[0174] Said step e) of Fischer-Tropsch synthesis produces water.

[0175] Advantageously, the water formed during step e) of the Fischer-Tropsch synthesis is partially or totally sent to step b) of electrolysis. Recycling the water formed in step e) back to step b) reduces the operating costs of the process according to the invention.

[0176] In one embodiment, the water formed during step e) of Fischer-Tropsch synthesis advantageously undergoes a treatment step before being recycled in step b) of water electrolysis so as to obtain the required specifications of step b). The treatment step may advantageously consist of removing oxygenated compounds from the water formed during step e).

[0177] The catalyst used in this step e) of the Fischer-Tropsch synthesis is generally any catalytic solid known to those skilled in the art that can carry out the Fischer-Tropsch synthesis. Preferably, the catalyst used in this step contains cobalt or iron, more preferably cobalt. The catalyst used in step e) is generally a supported catalyst. The support may be, for example, based on alumina, silica, or titanium.

[0178] The temperature and pressure conditions are variable and adapted to the catalyst used in this step (e). The absolute pressure is generally between 1.0 and 6.0 MPa, preferably between 1.5 and 3.5 MPa, and preferably between 2.0 and 3.0 MPa. The temperature can generally be between 170 and 280°C, preferably between 190 and 260°C, and preferably between 210 and 240°C.

[0179] Step e) of the Fischer-Tropsch synthesis is carried out in a reaction unit comprising one or more suitable reactors, the technology of which is known to those skilled in the art. These may be, for example, multitubular fixed-bed reactors, or slurry bubble column reactors, or microchannel reactors.

[0180] According to a preferred embodiment of the invention, step e) implements one or more bubble column reactors. Since the synthesis is highly exothermic, this embodiment allows, among other things, improved thermal control of the reactor and minimal pressure drop.

[0181] According to a variant of the process of the invention, at least part of the gaseous effluent from the Fischer-Tropsch synthesis step (step e) is advantageously recycled in the gasification step c) in order to be converted into synthesis gas and thus improve the mass yield of the process chain.

[0182] In one embodiment of the invention, at least part of the gaseous effluent from step e) of Fischer-Tropsch synthesis can advantageously be sent to the combustion unit(s) of steps a) and / or f), so as to supply energy to the drying operations a1) and / or the heat treatment operations a2) and / or the hydroconversion step (f) to maximize the energy efficiency of the process chain.

[0183] In another configuration of the process according to the invention, the gaseous effluent from the Fischer-Tropsch synthesis e) is advantageously at least partly sent to an independent synthesis gas production unit (for example POx: Partial oxidation, SM R: Steam Methane Reforming, ATR: Autothermal Reforming, EHTR: Enhanced Heat Transfer Reformer...), this synthesis gas can be recycled at any point in the chain.

[0184] In another configuration of the process according to the invention, the gaseous effluent from step e) of Fischer-Tropsch synthesis can be used to produce electricity in a combined cycle which can be partially powered by steam produced by steps c) and e) to increase the energy efficiency of the process chain.

[0185] These different configurations can be advantageously combined to optimize the economy of the integrated process chain according to the invention. f) Hydroconversion stage

[0186] According to the invention, the process of the invention comprises a step f) of hydroconversion and preferably hydrotreating and / or isomerizing at least a part and preferably all of the stream comprising liquid hydrocarbons from step e) of Fischer-Tropsch synthesis to produce at least one liquid biofuel cut and at least one gaseous effluent.

[0187] Step f) is carried out under normal operating conditions known to those skilled in the art in the presence of hydrogen and aims to valorize the liquid hydrocarbon fractions from step e) by the production of at least one liquid biofuel fraction, namely bio-naphtha, bio-gasoline, bio-kerosene, bio-diesel and very high quality bio-lubricating bases.

[0188] Said hydroconversion step f) advantageously comprises one or more combustion unit(s), preferably located upstream of the hydroconversion reactor, of said gaseous effluent produced in said step f) and / or of the gaseous effluent from step e). Said combustion unit of said step f) provides the thermal requirements of said step f) and possibly of one or more other steps of said process.

[0189] According to a preferred embodiment of the invention, said combustion unit of said step f) can be supplied with at least some of the oxygen from step b) of water electrolysis.

[0190] In another embodiment, the combustion unit of said step f) can be supplied by a flow of air optionally enriched with oxygen from step (b).

[0191] In these last two embodiments, the combustion unit advantageously includes a flue gas cooling stage that separates carbon dioxide from water vapor by condensation. In the case of combustion using air, the combustion section may be supplemented by a section for separating carbon dioxide from the nitrogen contained in the flue gases; this latter section may employ chemical or physical solvents, a mixture of chemical and physical solvents, or any other means known to those skilled in the art.

[0192] According to an implementation of feature B of the invention, the carbon dioxide stream produced by the combustion unit of said hydroconversion stage f) feeds the feed of stage (g), mixed with the carbon dioxide stream from stage (d) and the hydrogen stream from stage b).

[0193] More generally, all or part of the carbon dioxide stream produced by the combustion unit of the hydroconversion stage can be used as a by-product of the process to supply a transport network, a storage unit or any carbon dioxide recovery facility external to the process.

[0194] Advantageously, the water formed in the combustion unit of step f) of hydroconversion is partially or totally sent to step b) of electrolysis. Recycling the water formed in step f) to step b) reduces the operating costs of the process according to the invention.

[0195] In one embodiment, the water formed in the combustion unit of step f) of hydroconversion advantageously undergoes a treatment step before being recycled in step b) of water electrolysis so as to obtain the required specifications of step b).

[0196] The hydrogen required to carry out step f) can advantageously come in whole or in part from step b) of water electrolysis.

[0197] One possible option is the production of paraffinic cuts, basic products for petrochemical processes, for example production of a C10-C13 cut intended for the production of (bio) LAB (Linear Alkyl Benzene), or (bio) waxes for various industrial applications.

[0198] Step g) of carbon dioxide to hydrogen conversion (RWGS)

[0199] According to the invention, the process comprises a carbon dioxide to hydrogen conversion (RWGS) step in which the feed combining at least one hydrogen stream and one carbon dioxide stream has at least one of the following two characteristics:

[0200] A / at least a portion of the hydrogen stream from step b) is mixed with the carbon dioxide stream from step (d) and optionally with a carbon dioxide stream from one or more flue gas combustion units from steps (a) and / or (e) and / or (f), and optionally with a carbon dioxide stream external to the process such that the molar ratio of hydrogen to carbon dioxide H2 / CO2 at the inlet of step g) is adjusted between 1.8 and 3 and preferably between 1.8 and 2.5, the molar ratio H2 / CO at the inlet of step e) of Fischer-Tropsch synthesis is adjusted by another portion of the hydrogen stream from step b), and / or

[0201] B / The carbon dioxide stream from step (d) is mixed with a carbon dioxide stream from one or more gaseous effluent combustion units from steps (a) (e) and / or (f), and possibly with a carbon dioxide stream external to the process, the mixture of said carbon dioxide streams and the hydrogen stream from step b) feeding the carbon dioxide to hydrogen conversion (RWGS) step (g).

[0202] The said step (g) of carbon dioxide to hydrogen conversion (RWGS) enables the conversion of a feed combining at least one hydrogen stream and one carbon dioxide stream into at least one gaseous effluent comprising carbon monoxide CO and water vapor.

[0203] In particular, the gaseous effluent produced in step g) comprises a synthesis gas enriched in CO (and depleted in hydrogen) and also includes unconverted carbon dioxide and water vapor which is then advantageously condensed to recover water.

[0204] The gaseous effluent produced in step g) advantageously comprises a synthesis gas enriched in CO (and depleted in hydrogen) relative to the total carbon dioxide streams from step d) and from one or more combustion units of the gaseous effluents from steps a) and / or f) (streams 12 and 20).

[0205] According to the invention, after a water cooling and condensation step, the gaseous effluent from step g) of RWGS (flow 14) is sent to step d) for the removal of acidic compounds and impurities and preferably sent to a CO2 separation unit in step d4) or combined with the syngas from step d3).

[0206] According to the invention, all or part of the hydrogen flow required for the RWGS carbon dioxide to hydrogen conversion reaction of step g) comes from the water electrolysis step of step b).

[0207] According to one or more embodiments, said step g) comprises at least one reactor used under at least one of the following operating conditions:

[0208] - temperature between 700°C and 1200°C, preferably between 800°C and 1100°C, and even more preferably between 850°C and 1050°C;

[0209] - pressure between 0.1 MPa and 10 MPa, preferably between 0.1 MPa and 5 MPa, and more preferably between 0.1 MPa and 3.5 MPa;

[0210] - space velocity of the gas at the reactor inlet between 5000 NL / kg ca ta / h and 40000 NUkgcata / h;

[0211] - catalyst based on the elements Ni, Cu, Fe, Co or precious metals such as Pt, Pd, Ru, Ag and Au. According to one or more embodiments, the catalyst for the RWGS carbon dioxide to hydrogen conversion reaction of step g) comprises a support, for example based on alumina, silica, silica-alumina, alumina-silica.

[0212] According to one embodiment, step g) includes a heating section for the carbon dioxide streams from step d) and from one or more combustion units of the gaseous effluents from steps a) and / or f) as well as the hydrogen stream from step b) or the effluent resulting from the mixing of these streams feeding step g), said heating section enabling the temperature required for the reaction taking place in step (g) of conversion of carbon dioxide to hydrogen (RWGS) to be reached.

[0213] According to one implementation, said step g) includes at least one combustion unit, preferably located upstream of the carbon dioxide to hydrogen conversion reactor. Said combustion unit may advantageously be fueled at least in part by a fuel which may be a gas and preferably at least part of the gaseous effluents from step e) and / or step f).

[0214] According to a preferred embodiment of the invention, said combustion unit of said step g) can be powered by at least some of the oxygen from step b) of water electrolysis.

[0215] In one embodiment, the combustion unit of said step (g) may be supplied by an airflow, optionally oxygen-enriched, from step (b). In these last two embodiments, said combustion unit advantageously includes a flue gas cooling step for separating carbon dioxide from water vapor by condensation. In the case of combustion using air, the combustion section is optionally supplemented by a process for separating carbon dioxide from nitrogen contained in said flue gases, this separation being carried out by the use of chemical or physical solvents, a mixture of chemical and physical solvents, or any other means known to those skilled in the art.

[0216] According to an advantageous embodiment of the invention, the carbon dioxide stream produced by the combustion unit of said step g) feeds the charge of step (g), mixed with the carbon dioxide stream from step (d) and the hydrogen stream from step b).

[0217] More generally, all or part of the carbon dioxide stream produced from step d) or produced by the combustion unit of step g) can be used as a by-product of the process to supply a transport network, a storage unit or any carbon dioxide recovery facility external to the process.

[0218] Advantageously, the water formed by the RWGS reaction, as well as that formed by the optional combustion unit in step g), is partially or totally recovered and sent to the electrolysis step b). Recycling the water formed in step g) to step b) reduces the operating costs of the process according to the invention.

[0219] In one embodiment, the water formed by the RWGS reaction and that formed by the possible combustion unit of step g) advantageously undergoes a treatment step before being recycled in step b) of water electrolysis so as to obtain the required specifications of step b).

[0220] According to variant A of the invention, the quantity of hydrogen from step b) at the inlet of the reaction unit of step (g) is adjusted so that the H2 / CO2 molar ratio is between 1.8 and 3 and preferably between 1.8 and 2.5. Part of the hydrogen from step b) of water electrolysis is recombined with the purified synthesis gas from step d) to obtain an H2 / CO molar ratio compatible with the need of the FT unit, i.e. preferably between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5.

[0221] According to one embodiment, the gaseous effluent from step g) of RWGS, comprising CO, H2, unconverted CO2, and water vapor, has an outlet temperature from the reaction unit of step g) of at least 700°C, preferably at least 750°C, and most preferably at least 800°C. (See figure description.)

[0222] Figure 2 illustrates the different stages of the production process according to a particular embodiment of the invention.

[0223] The biomass is introduced into the pretreatment stage (A) via the pipe 1 in which it undergoes a drying stage a1), a roasting stage a2) and / or a grinding stage a3).

[0224] The pre-treated biomass is then sent via pipe 2 to a gasification stage in a unit (C) mixed with oxygen 11 produced during the water electrolysis stage which takes place in the water electrolysis unit (B).

[0225] The water used in the electrolysis unit (B) comes at least in part from the Fisher-Tropsch synthesis step implemented in unit (E) via pipe 9.

[0226] According to one embodiment of the invention, the water used in the electrolysis unit (B) comes at least in part from the combustion unit of the hydroconversion stage implemented in the unit (F) via the line 22.

[0227] According to one embodiment of the invention, the water used in the electrolysis unit (B) comes at least in part from the combustion unit of the pretreatment stage implemented in the unit (A) via the line 23.

[0228] According to one embodiment of the invention, the water used in the electrolysis unit (B) comes at least in part from the carbon dioxide hydrogen conversion step implemented in the unit (G) via the line 21.

[0229] During the water electrolysis stage, a flow of hydrogen is produced and sent via pipe 13 to stage (G) of RWGS.

[0230] According to one embodiment of the invention, during the water electrolysis step, a flow of hydrogen is produced and sent via the conduit 8 into the Fischer-Tropsch synthesis step (E).

[0231] The gasification step of the pretreated biomass, which takes place in unit (C) in the presence of oxygen (O1) from the water electrolysis step, produces a gaseous effluent comprising a synthesis gas. This gas exits the gasification unit (C) via line 3 and is sent to a step (d) for the removal of acidic compounds and impurities from the synthesis gas. This step may include a step (d1) of water scrubbing the synthesis gas and / or a step (d2) of catalytic hydrolysis of COS and HCN compounds and / or a step (d3) of water scrubbing, and a step (d4) of acid gas separation. This separation step (d4) is also fed by the gaseous effluent from step (G) via line 14 and treated in a separate or shared separation unit with the one supplied by the synthesis gas from line 3.Step d) further includes a step d5) for recombination of the gaseous effluents, either of the synthesis gas exiting unit (G) via line (3) with the gaseous effluent exiting directly from unit (G) via line 14, the resulting flow feeding a separation unit common to step d4) or of gaseous effluents depleted in acid gases from two separate separation units in step d4). Step d finally includes a step d6) for final purification of the effluent comprising the synthesis gas from step d4) or d5).

[0232] After purification, the carbon dioxide stream from unit D feeds unit G through pipe 12.

[0233] The effluent, including the possibly purified syngas, is then sent via line 5 to a Fischer-Tropsch synthesis step which takes place in unit (E). According to one embodiment of the invention, a portion of the hydrogen stream 8 produced during the water electrolysis step is sent to unit E. A stream 6 comprising synthetic liquid hydrocarbons is produced during the Fischer-Tropsch synthesis step and is sent to a hydroconversion step in unit F, which produces a stream 7 of synthetic liquid biofuels.

[0234] According to one embodiment of the invention, at least part of the gaseous effluent from unit (E) is recycled through line 17 into gasification unit C in order to be converted into synthesis gas.

[0235] According to one embodiment of the invention, part of the oxygen flow produced during the water electrolysis step is sent to one or more combustion units of unit A and / or unit F, respectively, through conduits 15 and / or 16.

[0236] According to one embodiment of the invention, the CO2 flows from one or more combustion units of unit A and / or unit F, respectively through pipes 18 and / or 19, supply unit G through pipe 20.

[0237] The examples illustrate the invention without limiting its scope.

[0238] Examples:

[0239] Example 1: Comparative example according to prior art document WO2014068253A1 not including an RGWS step or a water electrolysis step.

[0240] The following first comparative example refers to the processes implemented in Figure 1. Example 1 considers a unit that processes 100 t / h of dry biomass (1), yielding 80 t / h of torrefied biomass at the outlet of torrefaction pretreatment stage A. The torrefied biomass (2) contains 60 wt% carbon and 35% oxygen.

[0241] The gasification unit C, fueled by torrefied biomass (2) and a recycled gas stream from unit FT (17), produces 3 times more CO than CO2 in mol, i.e., a quantity of CO of 93.2 t / h. The H2 / CO ratio at the unit outlet is 0.5. A carbon monoxide water conversion unit, or water gas shift unit as it is known in English, increases the ratio from 0.5 to 2.1.

[0242] The Fischer-Tropsch synthesis step E produces a gaseous fraction which constitutes part of the effluents from block E.

[0243] Part of this gaseous effluent can be used as fuel to provide the energy needed for steps A and F.

[0244] The different stages of the process leading to the reduction of carbon yield are:

[0245] Roasting stage A with a 4% carbon loss.

[0246] The gasification step C with an additional 27% carbon loss.

[0247] The water gas shift step with a loss of 41% additional carbon.

[0248] The combustion of part of the gaseous effluent from the Fischer Tropsch E synthesis step for the thermal needs of steps A and F, with an additional 4% carbon loss

[0249] The overall carbon yield of the chain is therefore 24 wt%, i.e. a total material yield of 15 wt%.

[0250] The CO2 produced by the process is mainly produced in four stages:

[0251] - The combustion of pretreatment gases from pretreatment stage A represents 7.3 t / ha

[0252] - The gasification stage C represents 48.8 t / h.

[0253] - The water gas shift step D' for a flow rate of 75.5 t / h.

[0254] - The combustion of part of the effluent from the Fischer Tropsch E synthesis step for the thermal needs of steps A and F, representing 7.1 t / h

[0255] The amount of oxygen required to supply energy to gasification stage C is 66 t / h.

[0256] Figure 1 shows the different flows of Example 1 according to prior art WO2014 / 068253A1. Example 2: comparative example according to the process described in W02022 / 079407A1.

[0257] Figure 3 shows the main flows of the process chain according to comparative example 2.

[0258] The steps implemented in the process of Comparative Example 2 are identical to those of the process according to the invention. Example 2 is comparative in that the process described in document WO 2022 / 079407 does not meet either characteristic A or characteristic B of the present invention, in that Example 2:

[0259] - does not provide for the recycling of CO2 produced by the combustion units of stages A and F to stage G (flows 18 and 19 of figure 2 not shown in figure 4) (characteristic B);

[0260] - In that the molar ratio between hydrogen and carbon dioxide H2 / CO2 at the inlet of the reactor in step g) of carbon dioxide to hydrogen conversion (R-WGS) is equal to 7.3, i.e. outside the range claimed in characteristic A of 1.8 to 3.

[0261] Only the CO2 12 flux produced by the deacidification step D is treated in the R-WGS step G, i.e. a quantity of CO2 of 58.8 t / h.

[0262] The example takes into account a unit which processes 100 t / h of dry biomass 1 giving 80t / h of torrefied biomass at the output of step A. The torrefied biomass (2) contains 60 wt% carbon and 35% oxygen.

[0263] The gasification unit G, fed by torrefied biomass 2 and a recycled gas stream 17 from the FT synthesis stage E, produces 3 times more CO than 002 in mol, i.e., a quantity of CO of 102.6 t / h. The H2 / CO ratio at the unit outlet is 0.5. In this example, the H2 / CO ratio is increased from 0.5 to 2.1 at the inlet of the Fischer-Tropsch synthesis stage E (E) by an external hydrogen input (not shown in the figure) produced by water electrolysis B. The hydrogen flow rate injected at the inlet of the carbon dioxide conversion to hydrogen stage RWGS (stage G) is adjusted so that the H2 / CO ratio at the FT synthesis inlet is equal to 2.1 without the need for additional hydrogen (flow 8 in Figure 2 equal to zero).

[0264] The amount of hydrogen required for the R-WGS carbon dioxide hydrogen conversion reaction is 19.6 t / h in this case, with a flow rate of 58.8 t / h, resulting in a H2 / CO2 molar ratio of 7.3 at the inlet of the R-WGS carbon dioxide hydrogen conversion reactor in stage G. Adding a consumption of 0.6 t / h for the hydroconversion stage, the required hydrogen quantity is 20.2 t / h. To produce this quantity of hydrogen, the co-product of electrolysis, oxygen, is produced at a rate of 161 t / h. This flow rate is higher than the flow rate required for the gasification stage (72.5 t / h). The Fischer-Tropsch synthesis stage E produces a gaseous fraction that constitutes part of the effluents from block E.

[0265] Part of this gaseous effluent can be used as fuel to provide the energy required for the R-WGS reaction (step G), in addition to the fraction used as fuel for steps A and F. The carbon consumption corresponding to the combustion of this gaseous effluent from step E of FT synthesis for the thermal needs of steps A, F and G, is estimated in this example to be 22% of the carbon contained in the dry biomass.

[0266] The different stages of the process leading to the reduction of carbon yield are:

[0267] - Roasting stage A with a 4% loss of carbon.

[0268] - The combustion of part of the gaseous effluent from step E of FT synthesis for the thermal needs of step A, step F and step G, with an additional loss of 22% carbon.

[0269] The overall carbon yield of the chain is therefore 74% wt%, i.e. a total material yield of 44% wt%.

[0270] For the production capacity of this example, stage E of Fischer-Tropsch synthesis and stage G of CO2-to-hydrogen conversion produce approximately 88 t / h and 22 t / h of water respectively, representing 50% of the water requirement for the electrolysis stage, with a net water consumption of 109 t / h.

[0271] The CO2 released by the process according to example 2 is produced mainly in two stages:

[0272] - The combustion of pretreatment gases represents 7.3 t / h

[0273] - The combustion of a portion of the gaseous effluent from unit FT, totaling 41.2 t / h, is broken down as follows: 31.3 t / h for the combustion section of stage G (carbon dioxide conversion to hydrogen R-WGS), 4.2 t / h for the combustion section of the hydroconversion unit in stage F, and 5.7 t / h for the combustion section of pretreatment stage A.

[0274] The amount of oxygen required to supply energy to the gasification stage G is 72.5 t / h, which represents 45% of the oxygen produced by electrolysis.

[0275] Figure 3 shows the main flows of the process chain according to comparative example 2 according to prior art W02022 / 079407A1.

[0276] Example 3 according to the invention illustrating the operation of the invention according to feature A. Example 3 according to the invention below refers to the steps implemented in Figure 4.

[0277] It takes into account a process which treats 100 t / h of dry biomass (1) giving 80 t / h of torrefied biomass at the output of step A. The torrefied biomass (2) contains 60 wt% carbon and 35% oxygen.

[0278] Gasification step C produces 3 times more CO than CO2 in mol, i.e., a quantity of CO of 111 t / h. The H2 / CO ratio at the unit outlet is 0.5. In this example, the H2 / CO ratio is increased from 0.5 to 2.1 at the inlet of the Fischer-Tropsch synthesis step E by an external hydrogen supply (8) produced by water electrolysis B. The hydrogen flow rate (13) injected at the inlet of the carbon dioxide to hydrogen conversion step G R-WGS is adjusted according to the implementation of the invention such that the H2 / CO2 ratio at the inlet of the R-WGS reactor synthesis is between 1.8 and 3, and in particular equal to 2, corresponding to characteristic A according to the invention.

[0279] Example 3 does not reproduce feature B according to the invention in that the CO2 streams from step d), and the CO2 stream from the combustion units of the gaseous effluents of steps a), e) and f) are not recycled in mixture with the hydrogen stream from step b).

[0280] In this example, the quantity of hydrogen (13) injected at step G of the R-WGS carbon dioxide-to-hydrogen conversion process is 7.3 t / h, with a CO2 flow rate from step D (12) of 79.5 t / h, resulting in an H2 / CO2 molar ratio of 2 at the inlet of step G. To achieve an H2 / CO2 ratio of 2.1 at the inlet of step D of the Fischer-Tropsch synthesis process, an additional supply of external hydrogen (8) produced by water electrolysis (B) of 13.8 t / h is mixed with the synthesis gas (5) from step D. Adding a hydrogen consumption of 0.7 t / h for the hydroconversion step F, the total hydrogen requirement for the process is 21.7 t / h. To produce such a quantity of hydrogen, the co-product of water electrolysis, oxygen is produced at a rate of 172 t / h. This flow rate is greater than the flow rate required for the gasification step C via the pipe (11) (78 t / h).

[0281] The Fischer-Tropsch synthesis step E produces at least one gaseous effluent which constitutes part of the effluents of block E and a stream of liquid hydrocarbons (6) which is sent to the hydroconversion step F.

[0282] In addition to the portion of the gaseous effluent from step E used as fuel for steps A and F, another portion of this gaseous effluent from step E can be used as fuel to provide the energy required for the carbon dioxide conversion reaction R-WGS (step G). The carbon consumption corresponding to this loss of gaseous effluent from the FT is estimated in this example to be 16% of the carbon contained in the dry biomass.

[0283] The CO2 released by the process (and not recycled) is therefore produced mainly in two stages:

[0284] - The combustion of pretreatment gases represents 7.3 t / h

[0285] - The combustion of part of the gaseous effluent from the synthesis step FT E representing a total of 29.6 t / h, i.e. 19.3 t / h for the combustion unit of the carbon dioxide hydrogen conversion step R-WGS, 4.6 t / h for the combustion section of the hydroconversion step F and 5.7 t / h for the combustion section of the pretreatment step (A).

[0286] The different stages of the process leading to the reduction of carbon yield are therefore:

[0287] - The roasting stage with a 4% loss of carbon.

[0288] - The combustion of part of the gaseous effluent from step E of FT synthesis for the thermal needs of step A, step F and step G, with an additional loss of 16% carbon.

[0289] The overall carbon yield of the chain is therefore 80% wt, i.e. a total material yield of 48% wt.

[0290] The biofuel production yield of the chain is increased by 228% compared to the prior art process as described in Example 1, and by 9% compared to the process including a carbon dioxide RWGS hydrogen conversion step according to the prior art described in Example 2.

[0291] The implementation of the process according to the invention involves recycling, in the water electrolysis step B, water from the combustion flue gases of steps (A) and (F) (streams 23 and 22), as well as condensed water from the effluent of the RWGS reactor in step G and from the flue gases of the combustion unit in step G (21). By adding these various streams with the water produced by the Fischer-Tropsch synthesis step E, approximately 155 t / h of water is recovered, representing 66% of the water requirement of the electrolysis step B.

[0292] The amount of oxygen required to supply energy to the gasification stage G is 78.1 t / h, which represents 45% of the oxygen produced by electrolysis of water B.

[0293] The amount of CO2 emitted into the atmosphere amounts to 7.7 tonnes / tonne of biofuel produced and the water consumption for electrolysis is 1.7 tonnes / tonne of biofuel.

[0294] The CO2 emissions emitted per tonne of biofuel produced in the process according to the invention are reduced by 92% compared to the prior art scheme according to comparative example 1 (without electrolytic hydrogen and without step G of conversion of carbon dioxide to hydrogen RWGS) and by 30% compared to the balance according to comparative example 2. The water input for electrolysis referred to the production of biofuels is reduced by 32% compared to comparative example 2.

[0295] The implementation according to the invention therefore significantly improves the environmental performance of the sector.

[0296] Figure 4 shows the main flows of the process chain according to example 3 illustrating characteristic A according to the invention.

[0297] Example 4 according to the invention illustrating the operation of the invention according to characteristic B

[0298] It takes into account a process which treats 100 t / h of dry biomass (1) giving 80 t / h of torrefied biomass at the output of step A. The torrefied biomass (2) contains 60 wt% carbon and 35% oxygen.

[0299] Example 4 according to the invention below refers to the steps implemented in Figure 5 according to the claimed feature B in that the CO2 streams from step d), and the CO2 stream from the combustion units of the gaseous effluents of steps a), e) and f) are recycled in mixture with the hydrogen stream from step b).

[0300] In example 4, the gasification unit C, fed by torrefied biomass (2) and a recycled gas stream (17) from step E of FT synthesis, produces 3 times more CO than CO2 in mol, i.e., a quantity of CO of 103 t / h. The H2 / CO ratio at the outlet of the unit is 0.5. In this example, the H2 / CO ratio is increased from 0.5 at the outlet of step c) to 2.1 at the inlet of the Fischer-Tropsch synthesis step E by an external supply of hydrogen produced by electrolysis of water B. The hydrogen flow rate (13) injected at the inlet of the carbon dioxide to hydrogen conversion step G R-WGS (block G) is adjusted so that the H2 / CO ratio at the inlet of FT synthesis is equal to 2.1 without the need for additional hydrogen supply (flow 8 equal to zero).

[0301] The implementation of the process according to the invention involves the use of oxygen produced by water electrolysis B for the combustion units of stages A and F (flows 15 and 16), as well as the recycling of the CO2 produced by said stages to stage G (flows 18 and 19) (feature B according to the invention). To the CO2 flow (12) produced by the acid gas removal stage D of 60.6 t / h are added the flow 18 of 5.7 t / h and the flow 19 of 4.4 t / h, for a total quantity of CO2 of 70.7 t / h treated by the carbon dioxide to hydrogen conversion stage G R-WGS.

[0302] The amount of hydrogen required for the reaction in step G of R-WGS is 21.1 t / h in this case, with a CO2 flow rate of 70.7 t / h, resulting in a H2 / CO2 molar ratio of 6.5 at the inlet of the R-WGS carbon dioxide-to-hydrogen conversion reactor in step G. Adding a consumption of 0.6 t / h for the hydroconversion step F, the total hydrogen requirement is 21.7 t / h. To produce this quantity of hydrogen, the co-product of electrolysis, oxygen, is produced at a rate of 172 t / h.

[0303] The Fischer-Tropsch synthesis unit of step E produces at least one gaseous effluent which constitutes part of the effluents of block E and a stream of liquid hydrocarbons (6) which is sent to the hydroconversion step F.

[0304] Part of this gaseous hydrocarbon effluent can be used as fuel to provide the energy required for the R-WGS reaction. Contrary to prior art descriptions, the energy required for steps A and F is supplied by the combustion of a fraction of the gaseous effluent from step E of FT synthesis with a stream of pure oxygen (not shown in the figure) from electrolysis unit B. The pure CO2 stream (stream 20) resulting from this combustion is recycled to step G, which converts carbon dioxide to hydrogen. The carbon consumption corresponding to the loss of gaseous effluent from FT is therefore limited in this example to 19% of the carbon contained in the dry biomass.

[0305] The CO2 produced by the process therefore comes mainly from two stages:

[0306] - The combustion of pretreatment gases represents 7.3 t / h

[0307] - The combustion in the combustion unit of unit G of part of the gaseous effluent from step E of synthesis FT for the production of heat required for unit G of the carbon dioxide hydrogen conversion step RWGS representing a total of 34.8 t / h.

[0308] The different stages of the process leading to the reduction of carbon yield are therefore:

[0309] - Roasting stage A with a 4% loss of carbon.

[0310] - Combustion of part of the gaseous effluent from the FT unit for the thermal needs of stage G, with an additional loss of 19% carbon.

[0311] The overall carbon yield of the chain is therefore 77% wt, i.e. a total material yield of 47% wt.

[0312] The biofuel production yield of the chain is increased by 217% compared to the reference process as described in Example 1, and by 5% compared to the prior art RWGS process described in Example 2.

[0313] The implementation of the process according to the invention involves recycling the water from the combustion flue gases of steps (a) and (f) (streams 23 and 22) as well as the condensed water from the effluent of the RWGS reactor and the flue gases from the combustion unit of step G (stream 21). By adding these various streams with the water produced by step E of the Fischer-Tropsch synthesis, approximately 166 t / h of water is recovered, representing 71% of the water requirement for the electrolysis step. The quantity of electrolytic oxygen required for step C of gasification, as well as for the combustion sections of steps A and F, is 84 t / h, which represents 49% of the oxygen produced by electrolysis B.

[0314] The amount of CO2 emitted into the atmosphere is 9.1 tonnes per tonne of biofuel produced, and the water consumption for electrolysis is 1.5 tonnes per tonne of biofuel.

[0315] CO2 emissions per tonne of biofuel produced in the process according to the invention are reduced by 90% compared to the reference scheme according to comparative example 1 (without electrolytic hydrogen or step G of carbon dioxide conversion to hydrogen RWGS) and by 17% compared to the balance according to comparative example 2. The water input for electrolysis, relative to biofuel production, is reduced by 40% compared to comparative example 2. The implementation according to the invention therefore significantly improves the environmental balance of the sector.

[0316] Figure 5 represents the main flows in example 4 according to characteristic B according to the invention (H2 / CO2 = 6.5 at the RWGS inlet) with recycling of CO2 from combustion to block G.

[0317] Example 5 according to the invention illustrating the operation of the invention according to features A and B

[0318] It takes into account a process which treats 100 t / h of dry biomass (1) giving 80 t / h of torrefied biomass at the output of step A. The torrefied biomass (2) contains 60 wt% carbon and 35% oxygen.

[0319] Example 5 according to the invention below refers to the steps implemented in Figure 6 according to the claimed features A and B.

[0320] In example 5, gasification stage C, fed by torrefied biomass (2) and a recycled gaseous effluent (17) from FT synthesis stage E, produces 3 times more CO than CO2 in mol, i.e., a quantity of CO of 111 t / h. As in example 3, the H2 / CO ratio is increased from 0.5 to 2.1 at the inlet of Fischer-Tropsch synthesis stage E by an external hydrogen input (8) produced by electrolysis. The flow rate of hydrogen injected (13) at the inlet of stage G of R-WGS is adjusted according to the implementation of the invention such that the H2 / CO2 ratio at the inlet of stage G of R-WGS is equal to 2. The implementation of the process according to feature B of the invention includes the recycling of the CO2 produced by the gaseous effluent combustion steps in stages A and F to stage G (flows 18 and 19) (feature B).To the CO2 flux (12) produced by step D of removal of acid compounds of 83.3t / h are added the flux 18 of 5.7 t / h and 19 of 4.8 t / h i i a total quantity of CO2 of 93.9 t / h treated by step G of conversion of carbon dioxide to hydrogen (RWGS).

[0321] In this example, the quantity of hydrogen (13) injected at stage G of the carbon dioxide-to-hydrogen conversion (RWGS) process is 8.6 t / h for a CO2 flow rate of 93.9 t / h (flow 12 + 18 + 19), resulting in a molar H2 / CO2 ratio of 2 at the inlet of the R-WGS stage G reactor, according to process characteristic A. To achieve an H2 / CO2 ratio of 2.1 at the inlet of the Fischer-Tropsch reactor in stage E, an additional external hydrogen (8) produced by water electrolysis B of 14 t / h is mixed with the synthesis gas (5) from stage D, the acid gas removal stage. Adding 0.7 t / h for the hydroconversion stage F, the total hydrogen requirement is 23.3 t / h. To produce such a quantity of hydrogen, the co-product of electrolysis, oxygen is produced at a rate of 185t / h.

[0322] The Fischer-Tropsch synthesis step E produces at least one gaseous effluent which constitutes part of the effluents of block E and a stream of liquid hydrocarbons (6) which is sent to the hydroconversion step F.

[0323] Part of this gaseous effluent can be used as fuel to provide the energy required for the reaction in step G of R-WGS. Contrary to the prior art description, the energy required for step A is supplied both by the combustion of the pretreatment gases from step a) and by the combustion, in a separate combustion chamber, of a fraction of the gaseous effluents from step E with an oxygen stream from step B. Similarly, contrary to the prior art description, the energy required for step F is supplied by the combustion of a fraction of the gaseous effluents from step E of synthesis FT with a pure oxygen stream from electrolysis unit B, the pure O2 emitted resulting from the combustion of the gaseous effluents from step E being recycled to step G. The O2 produced by the combustion of the pretreatment gases from step a) is not recycled to step G.The carbon consumption corresponding to the loss in gaseous effluent from step E of FT synthesis is therefore limited in this example to 12% of the carbon contained in the dry biomass.

[0324] The CO2 produced by the process comes mainly from two stages:

[0325] - The combustion of pretreatment gases represents 7.3 t / h

[0326] - The combustion of part of the gaseous effluent from step E of FT synthesis for the production of heat required for step G of conversion of carbon dioxide to hydrogen (RWGS) utilities representing a total of 22.9 t / h.

[0327] The different stages of the process leading to the reduction of carbon yield are therefore:

[0328] - Roasting step A with a 4% carbon loss. - Combustion of part of the gaseous effluent from step E of FT synthesis for the thermal needs of step G with an additional 12% carbon loss.

[0329] The overall carbon yield of the chain is therefore 84% wt%, i.e. a total material yield of 50% wt%.

[0330] The biofuel production yield of the chain is therefore increased by 244% compared to the prior art process as described in Example 1, and by 14% compared to the RWGS process according to the prior art described in Example 2.

[0331] The implementation of the process according to the invention involves recycling the water from the combustion flue gases of steps (A) and (F) (streams 23 and 22) as well as the condensed water from the effluent of the RWGS reactor and the flue gases from the combustion section of step G (stream 21). By adding these different streams with the water produced by step E of the Fischer-Tropsch synthesis, approximately 167 t / h of water is recovered, representing 66% of the water requirement for step B of the electrolysis process.

[0332] The amount of electrolytic oxygen required to supply energy to gasification stage G, as well as for combustion in stages A and F, is 90t / h, which represents 49% of the oxygen produced by electrolysis.

[0333] The amount of CO2 emitted into the atmosphere is 6 tonnes per tonne of biofuel produced, and the water consumption for electrolysis is 1.7 tonnes per tonne of biofuel.

[0334] CO2 emissions per tonne of biofuel produced in the process according to the invention are reduced by 94% compared to the reference scheme according to comparative example 1 (without electrolytic hydrogen or step G of RWGS) and by 45% compared to the balance according to comparative example 2.

[0335] The water input for electrolysis, when considered in relation to biofuel production, is reduced by 31% compared to comparative example 2.

[0336] The implementation according to the invention, implementing the claimed characteristics A and B, therefore significantly improves the environmental balance of the sector compared to the prior art.

[0337] Figure 6 represents the main flows in Example 4 characteristics A + B according to the invention (molar ratio H2 / CO2 = 2 at the RWGS inlet) with recycling of CO2 from the combustion units of stages A and F to block G.

[0338] Example 6 = characteristics A + B (with recycling of CO2 produced by combustion of pretreatment gas in step G) In example 6, gasification step C fed by torrefied biomass (2) and a recycled gas stream (17) from FT synthesis step E produces 3 times more CO than CO2 in mol, i.e. a quantity of CO of 111 t / h.

[0339] As in Example 3, the H2 / CO2 ratio is increased from 0.5 to 2.1 at the inlet of step E of the Fischer-Tropsch synthesis by an external supply of hydrogen (8) produced by electrolysis. The flow rate of hydrogen injected (13) at the inlet of step G of carbon dioxide to hydrogen conversion (RWGS) is adjusted according to the implementation of the invention such that the H2 / CO2 ratio at the inlet of the reactor of step G of carbon dioxide to hydrogen conversion (RWGS) is equal to 2.

[0340] The H2 / CO ratio in the synthesis gas at the inlet of the FT synthesis step E is adjusted to 2.1 by an additional supply of external hydrogen produced by electrolysis of water B (flow 8).

[0341] The implementation of the process according to the invention involves using oxygen produced by electrolysis of water B for the combustion units of the gaseous effluents and pretreatment gases in blocks A and F (flows 15 and 16), as well as recycling the CO2 produced by said steps A and F to step G (flows 18 and 19). To the CO2 flow produced by step D for the removal of acidic compounds (86.2 t / h) are added flow 18 (13 t / h) and flow 19 (5 t / h), for a total quantity of CO2 of 104.2 t / h treated by step G for the conversion of carbon dioxide to hydrogen.

[0342] In this example, the amount of hydrogen injected at the R-WGS Stage G reactor is 9.6 t / h for a CO2 flow rate of 104.2 t / h, resulting in an H2 / CO2 molar ratio of 2 at the inlet of the R-WGS Stage G reactor. To achieve an H2 / CO2 ratio of 2.1 at the Fischer-Tropsch reactor inlet, an additional 14.1 t / h of external hydrogen produced by electrolysis of water B (flow 8) is mixed with the synthesis gas. Adding 0.7 t / h for the hydroconversion Stage F, the total hydrogen requirement is 24.4 t / h. To produce this quantity of hydrogen, the co-product of electrolysis, oxygen, is produced at a rate of 193 t / h.

[0343] The Fischer-Tropsch synthesis step E produces a gaseous hydrocarbon effluent which constitutes part of the effluents of block E.

[0344] Part of this gaseous effluent can be used as fuel to provide the energy needed for the reaction in step G of R-WGS.

[0345] Contrary to prior art descriptions, the energy required for steps A and F is supplied by burning a fraction of the gaseous effluents from step E of FT synthesis with a stream of pure oxygen from electrolysis unit B. The pretreatment gases from step A are mixed with the fraction of gaseous effluents from step E into the same combustion section of step A, and the pure CO2 emitted resulting from this common combustion section in step A is recycled to step G. The carbon consumption corresponding to the loss of gaseous effluent from FT is therefore limited in this example to 14% of the carbon contained in the dry biomass. The CO2 released by the process and therefore not recycled is produced mainly by the combustion in the combustion section of stage G of part of the gaseous effluent from stage E of FT synthesis for the production of heat required for stage G of RWGS, representing a total of 25.4 t / h.

[0346] The overall carbon yield of the chain is therefore 86% wt, i.e. a total material yield of 52% wt.

[0347] The biofuel production yield of the chain is therefore increased by 254% compared to the reference process as described in Example 1, and by 17% compared to the process including a carbon dioxide to hydrogen conversion step RWGS according to the prior art described in Example 2.

[0348] The implementation of the process according to the invention involves recycling the water from the combustion flue gases of steps (A) and (F) (streams 23 and 22) as well as the condensed water from the effluent of the RWGS reactor and the flue gases from the combustion section of step G (stream 21). By adding these different streams with the water produced by step E of the Fischer-Tropsch synthesis, approximately 175 t / h of water is recovered, representing 66% of the water requirement of the electrolysis step.

[0349] The amount of electrolytic oxygen required to supply energy to gasification stage G, as well as for combustion in stages A and F, is 103t / h, which represents 53% of the oxygen produced by electrolysis stage B.

[0350] The amount of CO2 emitted into the atmosphere amounts to 4.9 tonnes / tonne of biofuel produced and the water consumption for electrolysis is 1.7 tonnes / tonne of biofuel.

[0351] The CO2 emissions emitted per tonne of biofuel produced in the process according to the invention are reduced by 95% compared to the prior art scheme according to comparative example 1 (without electrolytic hydrogen or step G of carbon dioxide to hydrogen conversion RWGS) and by 55% compared to the balance according to comparative example 2. The water input for electrolysis referred to the production of biofuels is reduced by 30% compared to comparative example 2.

[0352] The implementation according to the invention therefore significantly improves the environmental performance of the sector.

[0353] Figure 6 shows the main flows of example 6 according to the invention (H2 / CO2 = 2 at the inlet of RWGS = characteristic A) with the oxygen combustion of the pretreatment gases and recycling of CO2 from the combustion of the effluents from the combustion units of A and F to block G.

[0354] The table below summarizes the main advantages of the process according to the invention illustrated by examples 3 to 6, compared to prior art processes without RWGS (example 1) or with RWGS (example 2).

[0355] Table 1

[0356] The table above highlights in particular the gain in biogenic carbon yield and in hydrocarbon yield of said process according to the invention, either by the implementation of the CO2 to hydrogen conversion reaction optimized by the control of the H2 / CO2 ratio according to example 3 (characteristic A) with a gain of 9% on the hydrocarbon production yield or productivity compared to the process according to the prior art implementing the RWGS reaction, or by the recycling of the carbon dioxide streams from steps A and F of the process (characteristic B) allowing a gain of 5% compared to the same reference according to example 4, or by the combined implementation of the two characteristics A and B according to the invention allowing a productivity gain of 14 to 17% according to examples 5 to 6.

[0357] Similarly, the implementation of the invention makes it possible to reduce CO2 emissions per kg of fuel produced by 30% compared to the prior art process WO22 / 079407 by optimizing the H2 / CO2 ratio according to example 3, or by 17% by recycling carbon streams from steps A and F in example 4, or by 45 to 55% by the combined implementation of the two features according to examples 5 to 6.

[0358] Finally, the implementation of the invention makes it possible to reduce water consumption for step B of electrolysis per kg of fuel produced by 32% compared to the prior art process WO22 / 079407 by optimizing the H2 / CO2 ratio according to example 3, and by 40% by recycling carbon streams from steps A and F in example 4.

[0359] In conclusion, the results of the various examples illustrate the advantages of the invention in significantly improving productivity, environmental performance and limiting the operating costs of the process.

Claims

DEMANDS 1. A process for converting a feedstock comprising at least a biomass fraction into hydrocarbons, and producing carbon dioxide, said process comprising at least the following steps: - possibly a step a) of pre-processing the load, - a step b) of electrolysis of water into oxygen and hydrogen allowing the obtaining of a flow of hydrogen, and a flow of oxygen, in which the water is obtained, at least in part, from a step e) of Fischer-Tropsch synthesis, - a step c) of gasification of the feed possibly pre-treated in step a), in the presence of all or part of the oxygen flow from step b) of water electrolysis so as to obtain a gaseous effluent comprising a synthesis gas, - a step d) of removing acidic compounds and impurities from the gaseous effluent comprising a synthesis gas from step c) mixed with a gaseous effluent from step g) after condensation of water vapor, so as to obtain a gaseous effluent comprising a purified synthesis gas and a carbon dioxide stream feeding at least in part a step (g) of conversion of carbon dioxide to hydrogen (RWGS), - a Fischer-Tropsch synthesis step e) of the gaseous effluent comprising a purified synthesis gas from step d) and possibly part of the hydrogen stream from step b) of water electrolysis so as to produce a stream comprising synthetic liquid hydrocarbons, water and at least one gaseous effluent, - a step (f) of hydroconversion of at least a portion of the stream comprising liquid hydrocarbons from step (e) to produce at least one liquid biofuel cut and at least one gaseous effluent - a carbon dioxide to hydrogen conversion step (g) to produce at least one gaseous effluent comprising carbon monoxide CO and water vapor, wherein the feed entering said step g) comprising at least a portion of the hydrogen stream from step b) and a carbon dioxide stream, has at least one of the following two characteristics: A / at least part of the hydrogen stream from step b) is mixed with the carbon dioxide stream from step (d) and possibly with a carbon dioxide stream from one or more combustion units of the gaseous effluents from steps e) and / or f) and / or possibly a), and possibly with a carbon dioxide stream external to the process, such that the molar ratio of hydrogen to carbon dioxide H2 / CO2 at the inlet of the reactor in step g) of carbon dioxide to hydrogen conversion is adjusted between 1.8 and 3, the molar ratio of hydrogen to carbon monoxide H2 / CO at the inlet of step e) of Fischer-Tropsch synthesis is adjusted by another part of the hydrogen stream from step b), and / or B / The carbon dioxide stream from step (d) is mixed with the hydrogen stream from step b) and a carbon dioxide stream from one or more combustion units of the gaseous effluents from steps e) and / or f) and / or possibly a), and possibly with a carbon dioxide stream external to the process, the mixture of said carbon dioxide streams and the hydrogen stream from step b) feeding the carbon dioxide to hydrogen conversion step (g) (RWGS).

2. A process according to claim 1 in which said pretreatment step a) comprises one or more gas combustion unit(s) and preferably pretreatment gas, produced in said step a) and preferably in a heat treatment operation a2), in which said gas is burned in a combustion step to produce combustion fumes containing carbon dioxide.

3. A method according to any one of claims 1 or 2 wherein an auxiliary gas combustion step, which may be natural gas and / or part or all of the gaseous effluents from step e) and / or f) is also carried out in said step a).

4. A method according to claim 3 in which the combustion steps of the pretreatment gas on the one hand and of the auxiliary gases on the other hand can be carried out in a common combustion unit or in two separate combustion units.

5. A method according to any one of claims 2 to 4 wherein the combustion unit(s) of said pretreatment step a) are supplied with at least some of the oxygen from the water electrolysis step b) or with an air stream possibly enriched with oxygen from step (b).

6. A method according to any one of claims 2 to 5 in which the combustion unit(s) include a combustion flue gas cooling step enabling the separation of carbon dioxide from water vapor by condensation.

7. A process according to any one of the preceding claims, wherein said hydroconversion step (f) comprises one or more combustion units, preferably located upstream of the hydroconversion reactor, of said gaseous effluent produced in said step (f) and / or of the gaseous effluent from step (e), supplied with at least a portion of the oxygen from step b) of water electrolysis or by an airflow possibly enriched with oxygen from step (b).

8. A method according to claim 7 wherein the combustion unit(s) comprise a combustion flue gas cooling stage enabling the separation of carbon dioxide from water vapor by condensation.

9. A method according to any one of the preceding claims wherein said step g) comprises at least one combustion unit, preferably located upstream of the carbon dioxide to hydrogen conversion reactor, supplied at least in part by a fuel being a gas and preferably at least a part of the gaseous effluents from step e) and / or step f) and by at least a part of the oxygen from step b) of water electrolysis or by an air stream possibly enriched with oxygen from step (b).

10. A method according to claim 9 wherein the combustion unit(s) of said stage g) comprise a combustion flue gas cooling stage enabling the separation of carbon dioxide from water vapor by condensation and the resulting carbon dioxide stream feeds the charge of stage (g).

11. A process according to any one of claims 2 to 10 wherein the water produced in any one of the process steps, and preferably the water produced in the combustion unit(s) of the wet biomass pretreatment step a) and / or the hydroconversion step f), preferably by condensation of the combustion fumes from said combustion units, the water produced in the Fischer-Tropsch synthesis step e), and the water produced in the carbon dioxide to hydrogen conversion (RWGS) step g), is recycled in the water electrolysis step b).

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