IMPROVED PROCESS FOR CONVERSION OF A FEED CONTAINING A BIOMASS FRACTION FOR THE PRODUCTION OF SYNTHETIC HYDROCARBONS FISCHER-TROPSCH.

Abstract

The present invention relates to a process for converting a feed comprising at least a biomass fraction into hydrocarbons, said process comprising a step a) of pretreatment of the feed, a step b) of electrolysis of water into oxygen and hydrogen allowing the obtaining of a hydrogen stream, and an oxygen stream, 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 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,an optional step d) of conditioning the gaseous effluent comprising a synthesis gas from step c) and a step e) of Fischer-Tropsch synthesis of the gaseous effluent from step c) or possibly from step d) in the presence of all or part of the hydrogen from step b) of water electrolysis so as to produce a stream comprising synthetic liquid hydrocarbons and at least one gaseous effluent. Figure to be published: Figure 1,

Description

Title of the invention: IMPROVED METHOD FOR CONVERTING A FEED CONTAINING A BIOMASS FRACTION FOR PRODUCTION FISCHER-TROPSCH SYNTHETIC HYDROCARBONS. technical field

[0001] The present invention relates to the valorization of biomass, typically for the production of liquid hydrocarbons, biofuels, and possibly the production of petrochemical bases and / or chemical bases and / or hydrogen.

[0002] More particularly, the present invention relates to an integrated process for converting a feed containing at least one biomass fraction comprising a gasification step, a water electrolysis step and a synthesis step by the Fischer-Tropsch reaction, for the production of hydrocarbons in particular LPG (Liquefied Petroleum Gas) fractions, naphtha, gasoline, kerosene and high-quality diesel or lubricant bases. Previous technique

[0003] A large number of patents describe synthetic hydrocarbon production chains by Fischer-Tropsch synthesis, which often includes hydrotreating and isomerizing steps for the hydrocarbon cuts obtained from this synthesis.

[0004] Patent application WO2014068253A1 implements a biofuel production chain from lignocellulosic biomass. This 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 of the biofuel production chain.

[0005] US patent 9562196 describes a process for producing synthetic hydrocarbons in which the hydrogen content at the inlet of the Fischer-Tropsch unit is adjusted by reforming the naphtha produced by the Fischer-Tropsch synthesis. This step has the disadvantage of reducing the quantity of finished products produced by consuming the naphtha produced and therefore reduces the productivity of the Fischer-Tropsch synthesis step.

[0006] Patent application WO 2015 / 101717 describes an external hydrogen input for adjusting the H2 / CO ratio of a synthesis gas produced by the gasification of a carbon feedstock, and more particularly biomass. In particular, this document This describes a process comprising a step of converting carbon monoxide to steam to enrich the synthesis gas produced by gasification with hydrogen, and a step of adjusting the synthesis gas production according to the amount of hydrogen by externally supplying hydrogen in order to maintain a constant production of synthetic fuel. The carbon monoxide-to-steam conversion reaction is also called the "Water Gas Shift" reaction in Anglo-Saxon terminology.

[0007] One of the problems encountered by a person skilled in the art in the field of the 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.

[0008] In the case of the present invention, the applicant proposes a new process which presents an optimal integration of the gasification, Fischer-Tropsch synthesis and water electrolysis steps, enabling 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. Summary of the invention

[0009] In particular, the invention relates to a process for converting a feed comprising at least a biomass fraction into hydrocarbons, said process comprising

[0010] - a step a) of pre-treating the load,

[0011] - 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 originates, at least in part, from a step e) of Fischer-Tropsch synthesis,

[0012] - a step c) of gasification of the feed pretreated 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,

[0013] - an optional step d) of conditioning the gaseous effluent comprising a synthesis gas from step c) so as to obtain a gaseous effluent comprising purified synthesis gas,

[0014] - a step e) of Fischer-Tropsch synthesis of the gaseous effluent from step c) or possibly from step d) in the presence of all or part of the hydrogen from step b) of water electrolysis so as to produce a stream comprising synthetic liquid hydrocarbons and at least one gaseous effluent.

[0015] An advantage of the present invention is to provide a process which has an optimal integration of the steps of gasification, Fischer-Tropsch synthesis and water electrolysis 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.

[0016] Another advantage of the process according to the invention is to limit, and even eliminate, the implementation of the steam conversion step to generate hydrogen, which makes it possible to reduce CO2 emissions from the biofuel production process and also to maximize the amount of CO from the gasification step and thus increase the material yield of the process and / or reduce the amount of input feedstock. Description of the implementation methods

[0017] The present invention relates to a method for converting a feed comprising at least a biomass fraction into renewable hydrocarbons.

[0018] Types of charges

[0019] The biomass fraction may 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 residues, forestry products, sawmill residues, waste wood, dedicated crops, short-rotation coppice or very short-rotation coppice.

[0020] 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" according to Anglo-Saxon terminology). Said hydrocarbon feed fraction is understood within the scope of the present invention as a feed fraction that may advantageously contain at least coal, petroleum coke (petcoke according to 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, visbreaking residue or similar thermal process residue, etc.).), oil sands or their derivatives, shale gas and oil shale or their derivatives, liquid biomass (such as rapeseed oil, palm oil, pyrolysis oil,...), biomass in slurry according to the . Anglo-Saxon terminology corresponding to a mixture of liquid biomass with a solid hydrocarbon feedstock. According to the process of the invention, said hydrocarbon feedstock fraction may be a gaseous, solid, liquid hydrocarbon feedstock fraction or a mixture thereof.

[0021] The feed of the process according to the invention can therefore be a feed comprising at least a solid biomass fraction, and optionally at least a fraction of another gaseous, solid or liquid feed alone or in mixture.

[0022] Generally, the feed 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 more preferably at least 90% biomass fraction.

[0023] The different stages of the process according to the invention are described below.

[0024] a) Load pretreatment step

[0025] According to the invention, the process comprises a pretreatment step a) of the feed. Preferably, the pretreatment step comprises at least one of the drying (a1), roasting (a2), or grinding (a3) ​​operations described below. Preferably, the pretreatment step comprises a drying operation (a1), a roasting operation (a2), and a grinding operation (a3).

[0026] In an embodiment where the load used is already dry, the pretreatment step includes a roasting operation a2) and a grinding operation a3).

[0027] When the hydrocarbon feed fraction is a gaseous or liquid hydrocarbon feed fraction, it is advantageously introduced directly into step c) of gasification without being subjected to step a) of pretreatment.

[0028] al) Drying operation

[0029] Step a) of pretreating the feedstock may advantageously include a drying operation a1) of the feedstock, 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 between 5 and 180 minutes and preferably between 15 and 60 minutes. At the start of the drying operation a1), the feedstock generally has a moisture content between 15 and 80% by mass. The residual moisture content in the feedstock after 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.

[0030] The energy required for drying is generally supplied by bringing the load into contact with a flow of hot gases.

[0031] The hot gas stream used in the drying step can advantageously originate from the combustion of a process input, and preferably from the combustion of natural gas and / or from the combustion of a gas stream from another step of the process. For example, the combustion of gases from roasting step a2 produces a hot gas stream that can be used to dry the feedstock using any method known to those skilled in the art.

[0032] The gaseous effluent from step a1) containing water can be used to preheat the air enabling the combustion of natural gas and / or the gaseous stream produced during roasting.

[0033] The water contained in the gaseous effluent from step a1) can advantageously be condensed and recycled in step b) of electrolysis of the process according to the invention.

[0034] a2) Roasting operation

[0035] Step a) of pretreatment of the feed may include a roasting operation a2), preferably of the dried feed resulting from the drying operation al).

[0036] The roasting operation a2) can be carried out in a roasting oven which produces a more friable 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.

[0037] The roasting operation has the advantage of reducing the energy cost of operation a3) grinding and is accompanied by 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 more limited loss of calorific value, on the order of 5 to 20%. As such, the roasting operation makes it possible to increase the volumetric energy content of the biomass, that is to say, its energy per unit volume.

[0038] a3) Grinding operation

[0039] Step a) of pretreatment of the feed may include a grinding operation a3), preferably of the roasted effluent from operation a2).

[0040] The grinding operation a3) can be carried out under conditions allowing a reduction of the particle load to a size suitable for processing in a unit of entrained flow gasification (step c). At the end of the grinding operation a3), 90% of the feed particles preferably have an equivalent diameter of less than 300 microns and 90% of the feed particles preferably have an equivalent diameter greater than 1 micron; preferably, 90% of the feed particles have an equivalent diameter of less than 200 microns and 90% of the feed particles have an equivalent diameter greater than 5 microns; and most preferably, 90% of the feed particles have an equivalent diameter of less than 100 microns and 90% of the feed particles have an equivalent diameter greater than 10 microns. The equivalent diameter, denoted by , is defined, for example, according to the following relationship:

[0041] with V being the volume of the particle,

[0042] S the surface of the sphere of the same volume as the particle.

[0043] In a particular embodiment, the grinding step a3) 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 said second feed is fossil, it can be chosen from solid fossil hydrocarbons such as coal or petroleum coke (petcoke in Anglo-Saxon terminology). When said second feed is biomass, it can be chosen from the biomass feeds as defined above. 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.

[0044] Preferably, step a3) of grinding can be carried out in the presence of an additional compound useful for the subsequent gasification step, said compound is chosen from vitrified ashes, sand, limestone, lime or other compounds known to the person skilled in the art taken alone or in mixture.

[0045] Preferably, the mill is chosen so as to optimize the pneumatic transport of the powder obtained at the end of step a3), minimizing the minimum fluidization velocity (UMF), as well as its own energy consumption.

[0046] Preferably, said co-crushing step a3) is carried out in a roller mill, universal mill, attrition mill, or any other type of mill known to those skilled in the art

[0047] Electrolysis step b)

[0048] The process according to the invention comprises a step 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 and preferably in whole, from step e) of Fischer-Tropsch synthesis.

[0049] The oxygen obtained at the end of step b) is sent in part or in whole to step c) of gasification. Advantageously, the oxygen produced by electrolysis has a purity of at least 98.5% by weight (on a dry basis). Impurities that may be present in the oxygen produced are water and / or hydrogen.

[0050] According to the invention, all or part of the hydrogen obtained from step b) of electrolysis is sent to step e) of Fischer-Tropsch synthesis.

[0051] Advantageously, the hydrogen obtained from step b) of electrolysis and sent to step e) of Fischer-Tropsch synthesis 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.

[0052] In a preferred mode, all of the hydrogen produced in step b) of electrolysis is introduced in step e) of Fischer-Tropsch synthesis.

[0053] Advantageously, the molar ratio between hydrogen and 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, the hydrogen coming from step d) conditioning of the synthesis gas and step b) of water electrolysis.

[0054] Step b) of electrolysis can be carried out by any means known to a person skilled in the art, for example by alkaline electrolysis, by proton exchange membrane, by anion exchange membrane, or by solid oxide electrolysis.

[0055] An 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 II directive.

[0056] Another advantage of recycling water from step a1) of drying and / or step e) of Fischer-Tropsch synthesis to step b) of electrolysis is to reduce the water consumption of the process and consequently the operating costs.

[0057] Another advantage of step b) electrolysis is that the oxygen produced is used in the process in step c) gasification, which 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 (for Sulfur Recovery Unit / Tail Gas Treating Unit, according to English terminology) and / or for oxy-combustion of fuel gas from the unit and residual gas, and / or for burning roasting gases.

[0058] Gasification step c)

[0059] The process according to the invention comprises a step c) of gasification of the feed, pretreated in step a), said step c) is carried out in the presence of all or part of the oxygen from step b) of water electrolysis and preferably all of the oxygen from step b) of water electrolysis. Step c) of gasification thus allows obtaining a gaseous effluent containing a synthesis gas.

[0060] The gasification step implements a partial oxidation reaction that converts the feed into a synthesis gas consisting mainly of carbon monoxide and hydrogen. The gasification step is advantageously carried out in the presence of a controlled quantity of oxygen from step b) of electrolysis in the form of an oxygen stream having a purity of at least 98.5% by weight (on a dry basis). The use of this oxygen makes it possible to limit the quantity of inert compounds, such as nitrogen when using air as the oxygen source, which limits the accumulation of inerts and therefore the problems related to pressure or velocity losses, and thus reduces the size of the equipment used, further limiting the investment and operating costs of the process.

[0061] 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 from the fraction of another feed, in particular hydrocarbon feed.

[0062] According to the invention, the oxygen used in the gasification step is derived in whole or in part from step b) of water electrolysis.

[0063] 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.

[0064] In a particular embodiment, all of the oxygen introduced in the gasification step c) comes from the water electrolysis step b).

[0065] 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 makes it possible to obtain a high carbon conversion rate and thus reduce the amount of unconverted carbon in the ash produced, thereby reducing the amount of ash recycled to the gasifier.

[0066] 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 delimits 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 placed outside the wall of the gasification chamber. The water The gas is partially vaporized, 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. The feedstocks introduced into the gasifier contain inorganic compounds, which form ash after gasification. At the gasification temperature, these liquid ash droplets solidify upon contact with the cooled wall, forming a solid layer that acts as insulation. Thus, the thermal protection of the gasification chamber wall is ensured by a layer of solidified ash and a layer of molten ash in contact with the gas phase, flowing 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 alkaline content, biomass ash is corrosive to refractory linings. Consequently, gasification technologies using internal refractories as wall protection are difficult to operate because of their rapid deterioration, necessitating frequent replacement. In addition, refractories are highly susceptible to thermal shock, which destroys this protective layer through fracturing.

[0067] In the cooled-wall entrained-flow gasifier, at least two burners, and preferably four or more depending on the gasifier's capacity, are arranged in the gasification chamber, the walls of which are cooled and which operate at a temperature sufficient to allow the melting of the ash contained 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 melting point of the ash can vary considerably from one biomass to another. Thus, the melting point of the ash 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 varying the nature of the feedstock, which has different properties, and the proportions of the different constituents (other biomass, other hydrocarbon feedstock, etc.) and / or by injecting fluxing agent (for example limestone) with the feedstock.

[0068] In a preferred embodiment of the invention, the syngas produced in the gasification chamber exits it in a co-current manner with the liquid ash flowing to the bottom of the gasifier. This co-current 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 risks of blockages in the liquid ash discharge pipe are significant. Indeed, liquid ash flowing alone in the pipe can, depending on its viscosity, flow with difficulty and / or partially solidify, partially or completely obstructing the discharge pipe and requiring the installation to be shut down for maintenance. These phenomena can occur particularly during transient 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 co-currently with the liquid ash in the discharge pipe of the gasification chamber facilitates the flow of this ash to the bottom of the gasifier and prevents the risk of blockages, even during transient phases.

[0069] 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 DE 102007044726. 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 at the outlet of the cold, wet zone corresponds to the thermodynamic equilibrium temperature between the gas and liquid phases at the operating pressure of the gasifier.

[0070] This configuration with a quench allows for the removal of fine, sticky ash particles carried along during the synthesis gas scrubbing, thus reducing the risk of fouling in downstream piping and units. Furthermore, the high temperature in the gasification chamber allows the molten ash to flow easily downwards down its wall before falling into the quench zone. After passing through the cold, humid unit, the cooled ash ends up at the bottom of the water-filled gasifier. Upon contact with the water, this 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 contained in the feedstock form the molten ash.This configuration advantageously allows for the encapsulation of hazardous products such as heavy metals within vitrified ash. The vitrification process renders this ash highly stable and impermeable to leaching.

[0071] In an alternative embodiment of the invention, the synthesis gas produced exits the gasification chamber from the top while the molten ash flows along From the counter-current flow of the synthesis gas to the bottom of the water-filled gasifier, the molten ash solidifies abruptly upon contact with the water, 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 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. The synthesis gas exits the gasification chamber from the top, and the finest molten ash particles carried with it are cooled by a stream of chilled synthesis gas free of solid particles. This cooling process solidifies the molten ash into non-sticky solid particles.After this initial preliminary cooling stage, the syngas is directed to a heat exchanger to produce steam. To remove 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 to the gasifier outlet to cool the syngas exiting the top of the gasifier.

[0072] Optional step d) of syngas conditioning

[0073] The process according to the invention may include a step d) of conditioning the syngas from the gasification step c). The syngas from the gasification step c) 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 from 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).

[0074] Preferably, step d) comprises, preferably consists of, steps d1) and / or d2) and / or d3) and / or d4) and / or d5) and / or d6) and / or d7 and / or d8).

[0075] Step d1) of water washing and synthesis gas fractionation

[0076] Preferably, step d) includes a step dl) of washing with water and fractionating the synthesis gas.

[0077] Thus, the synthesis gas from step c) of gasification is advantageously subjected to a step dl) of washing with water to remove traces of solid in the Synthesis gas, as well as some of the water-soluble gaseous compounds, can be removed. This operation can be carried out using any technique known to those skilled in the art, including water scrubbers with a venturi effect (or venturi scrubber, according to Anglo-Saxon terminology), scrubbing columns with all types of internal components, etc.

[0078] Preferably, at the outlet of the water washing step, the syngas is subjected to a fractionation step into at least two effluents, a first part and a complementary part subjected to the following steps:

[0079] - a step d2) of removing halogenated compounds by passing said first part on at least one suitable daycare bed;

[0080] - possibly a step d3) of converting carbon monoxide to steam carried out on the effluent from step d2);

[0081] - a step d4) of catalytic hydrolysis of the COS and HCN compounds contained in said supplementary part of the effluent from step dl) in H2S and NH3

[0082] In another embodiment, the effluent from step d3) is advantageously recombined with the complementary part of the effluent from step d1) before being treated in step d4) of catalytic hydrolysis of the COS and HCN compounds.

[0083] Thus, the so-called first-part and supplementary effluents from step d1) of water washing and synthesis gas fractionation are subjected to separate treatment steps. The first part undergoes a step d2) of halogenated compound removal; while the supplementary part undergoes a step d4) of catalytic hydrolysis of the COS and HCN compounds into H2S and NH3. The fractionation of the synthesis gas and the separate treatment of the effluents allow for a reduction in the size of the units and the quantities of catalysts used in said units.

[0084] Preferably, the respective proportions of said first part of the effluent from step d1) and of said complementary part are advantageously determined in order to obtain an effluent at the outlet of step d7) which feeds the Fischer-Tropsch step e) with a molar ratio H2 / CO advantageously between 0.5 and 4, preferably between 1 and 3, more preferably between 1.5 and 2.5, and preferably equal to 2.

[0085] Step d2) of elimination of halogenated compounds

[0086] Preferably, step d) includes a step d2) for the removal of halogenated compounds.

[0087] Step d2) of removing halogenated compounds on at least one suitable guard bed is advantageously carried out on the first part of the effluent from step d1). Step d2) makes it possible to substantially remove the halogenated compounds, advantageously chlorine, contained in said first part of the effluent before the latter is sent to a carbon monoxide conversion unit. steam (step d3). Fixed-bed reactor technology will be advantageously preferred for capturing halogenated compounds, particularly chlorine contained in the synthesis gas of said first part, using capture media known to those skilled in the art. Advantageously, step d2) is carried out on at least one guard bed in the presence of a capture media containing an active phase of the zeolite type, and / or zinc oxide, and / or a basic oxide such as alumina. The active phase may be doped or promoted by one or more compounds of alkali and / or alkaline earth elements and / or rare earth elements. The active phase may, for example, be alumina promoted by a sodium compound, for example by Na₂O.

[0088] In the context of the invention, passing the first part of the effluent from step d1) through at least one guard bed makes it possible to achieve the specifications required for the carbon monoxide to steam conversion unit d3). At the outlet of step d2) of removal of halogenated compounds, the effluent generally contains less than 10 ppm by volume of chlorine, advantageously less than 5 ppm by volume of chlorine, preferably between 0.1 ppm and 5 ppm by volume of chlorine, more preferably between 1 ppm and 3 ppm by volume of chlorine, and even more preferably between 1 ppm and 2 ppm by volume of chlorine.

[0089] Step d3) of conversion of carbon monoxide to steam

[0090] The synthesis gas conditioning step d) optionally includes a step of converting carbon monoxide to steam.

[0091] 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.

[0092] In order to achieve the H2 / CO molar ratio required by the Fischer-Tropsch synthesis, the effluent from step d2) of removal of halogenated compounds is according to the invention, optionally directed to a section of conversion of carbon monoxide to steam d3) allowing to produce a gaseous stream rich in hydrogen and depleted in carbon monoxide.

[0093] Step d3) is implemented in the case where the hydrogen produced in step b) of water electrolysis does not allow obtaining the desired H2 / CO ratio at the input of step e) of Fischer Tropsch synthesis.

[0094] All or part of the hydrogen produced in step d3) of carbon monoxide to steam conversion can advantageously also be sent to step e) of Fischer Tropsch synthesis.

[0095] The carbon monoxide to steam conversion reaction step d3) is advantageously carried out at an inlet temperature close to the temperature of the synthesis gas from the water washing and fractionation step d1), thereby reducing energy consumption throughout the biomass valorization chain. Preferably, step d3) is carried out at an inlet temperature between 150 and 280 °C, preferably between 200 and 280 °C.

[0096] Advantageously, the carbon monoxide to vapor conversion reaction step d3) is carried out at an absolute pressure of between 2.0 and 12 MPa, preferably between 2.5 and 6.0 MPa, and more preferably between 3.0 and 5.0 MPa; at an hourly volumetric rate WH (volume of charge / volume of catalyst / hour) of between 1000 and 10000 h-1, preferably between 1000 and 9000 h-1 and more preferably between 1500 and 8500 h-1; at a temperature of between 150 and 550°C, preferably between 200 and 500°C.

[0097] The catalyst used in this step (d3) is a catalyst comprising at least one element from Group VIII and / or at least one element from Group VIB of the Mendeleev periodic table (Group VIII corresponds to Groups 8, 9, and 10, and Group VIB to Group 6 according to the new notation of the periodic table of elements: Handbook of Chemistry and Physics, 81st edition, 2000-2001). Preferably, the catalyst is a catalyst comprising cobalt sulfide and / or molybdenum sulfide. The catalyst support is usually a porous solid selected from the group consisting of aluminas, silica, and alumina silicas. Preferably, the catalyst support is alumina. The catalyst used may be promoted with an alkali or alkaline earth promoter. The carbon monoxide conversion reaction makes it possible to considerably increase the hydrogen content in the effluent directed to step e) of Fischer-Tropsch synthesis.

[0098] If necessary, water in liquid form, preferably in vapor form and preferably in superheated vapor form, may be added upstream of the carbon monoxide-to-steam conversion step to adjust the H2O / CO ratio at the inlet of the unit in step d3). Advantageously, step d3) is carried out with an H2O / CO ratio between 0.5 and 100, preferably between 0.5 and 25, and more preferably between 1.5 and 10. Due to the exothermic nature of the carbon monoxide-to-steam conversion reaction, the gaseous effluent from this step has a temperature between 250 and 550°C. This gaseous effluent is advantageously cooled to the operating temperature of the hydrolysis unit, between 100 and 400°C, preferably between 200 and 350°C.This cooling is advantageously achieved by generating water vapor which can be used either in the process chain according to the invention, or to produce electricity.

[0099] In a variant of the process according to the invention, the H2 / CO molar ratio of the gas stream entering step e) of the Fischer-Tropsch synthesis can be adjusted to its optimal level of approximately 2 to be directed towards the production of middle distillates by adding an external hydrogen-rich gas stream produced by any means known to those skilled in the art, including: water electrolysis, steam reforming of natural gas followed by a pressure swing adsorption (PSA) or temperature swing adsorption (TSA) separation step, or by membrane separation. This hydrogen-rich gas stream can be injected at any point in the chain downstream of the gasification step c) and makes it possible to reduce the size of step d3) of carbon monoxide to steam conversion.

[0100] In a variant of the process according to the invention, a portion of the gas from step d3) of carbon monoxide-to-steam conversion, but also possibly upstream or downstream of said step d3), can advantageously be sent to a hydrogen production unit implemented by any means known to those skilled in the art, preferably by pressure swing adsorption (PSA), temperature swing adsorption (TSA), or membrane separation. The hydrogen produced is advantageously used in step f) of hydrotreating and / or isomerization.

[0101] Step d4) of catalytic hydrolysis of COS and HCN compounds

[0102] Preferably, step d) includes a step d4) of catalytic hydrolysis of the COS and HCN compounds from the complementary part obtained from step d1).

[0103] The additional portion obtained from step d1) is subjected to a step d4) of catalytic hydrolysis of COS and HCN to H2S and NH3, resulting in a purified effluent. This step allows the removal of COS and HCN, which are poisons for the Fischer-Tropsch synthesis catalyst. The step d4) of catalytic hydrolysis of carbon oxysulfide (COS) and hydrogen cyanide (HCN) is, according to the invention, advantageously carried out in the presence of a catalyst containing a platinum-based compound, or an oxide of an element selected from the group comprising titanium, zirconium, aluminum, chromium, zinc, or a mixture thereof.

[0104] 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 potash, zirconium oxide, sodium or barium carbonate, sodium or barium bicarbonate, calcium sulfate, sodium or barium acetate, 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.

[0105] Advantageously, the effluent at the outlet of the hydrolysis unit of step d4) contains less than 25 ppm volume of COS and less than 5 ppm volume of HCN, preferably less than 10 ppm volume of COS and less than 1 ppm volume of HCN, and more preferably less than 5 ppm volume of COS and less than 0.1 ppm volume of HCN.

[0106] 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.

[0107] Recombination step d5)

[0108] Preferably, at least a fraction and preferably all of the effluent from step d2) of removal of halogenated compounds and possibly from step d3) of conversion of carbon monoxide to steam is recombined in step d5) with at least part of the effluent from step d4) of catalytic hydrolysis before being sent to step d6) of washing with water.

[0109] Step d6) of washing the recombined effluent with water

[0110] Preferably, step d) includes a step d6) of washing with water the mixed effluent obtained at the end of steps d2) and d4). Step d6) makes it possible to remove impurities such as NH3 and HCl which are soluble in water and particularly harmful to the operation of step d7) of removing acid gases.

[0111] In a variant of the process according to the invention, the mixed effluent obtained at the end of steps d2) and d4) may be pre-treated with a heavy metal removal step on at least one suitable guard bed. This removal step makes it possible to substantially remove heavy metals, such as lead, arsenic, and mercury, before the effluent is treated in step d6) of water washing and, more particularly, before step d7) of acid gas removal. Fixed-bed reactor technology will advantageously be preferred for capturing the heavy metals contained in the syngas 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.

[0112] Advantageously, passing the effluent through at least one guard bed of the removal stage makes it possible to achieve the required specifications at the inlet of the acid gas removal stage d7 (stage d7), as well as the required specifications for the Fischer-Tropsch synthesis unit of stage e).

[0113] In a second embodiment according to the invention, the heavy metal removal step is carried out between step d6) of water washing and step d7) of acid gas removal.

[0114] In a third embodiment according to the invention, the heavy metal removal step is carried out after step d7) of acid gas removal when the solvent used in step d6) is a chemical solvent derived from alkanolamine, known to those skilled in the art to be less sensitive than physical solvents to the presence of heavy metals.

[0115] At the outlet of the heavy metal removal step, the effluent generally has a content of less than 1 ppb volume of lead, arsenic and mercury, preferably less than 0.5 ppb volume, more preferably less than 0.1 ppb volume and even more preferably less than 0.01 ppb volume of lead, arsenic and mercury.

[0116] Step d7) of acid gas removal

[0117] Preferably, step d) may advantageously further include a step d7) for removing acid gases. Step d7) is dedicated to removing acid gases such as sulfur compounds (H2S) or CO2 remaining in the synthesis gas from step d5).

[0118] Said step d7) is advantageously implemented in the case where the CO2 content in the synthesis gas from step d6) is greater than 5% by weight relative to the weight of said effluent, preferably greater than 10% by weight and preferably greater than 20% by weight.

[0119] Step d7) 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). 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.

[0120] The acid gas removal step is, for example, carried out using an acid gas absorption column with the chemical or physical solvent used, followed by a solvent regeneration step to reduce solvent consumption in the unit. This regeneration step can advantageously be carried out 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. In a variant of the process according to the invention, said gas stream rich in CO2 is purified of H2S and advantageously recycled in step c) of gasification.

[0121] Step d8) of final purification

[0122] Preferably, step d) includes a final purification step d8). This is because the cobalt-based catalyst used in step e) of the Fischer-Tropsch synthesis is highly sensitive to impurities present in the synthesis gas, which are therefore only tolerated in quantities on the order of ppb (parts per billion). At the outlet of step d7), the synthesis gas may still contain impurities at concentrations of approximately 100 ppb by volume of H2S and COS.

[0123] Advantageously, the final purification step d8) is carried out on at least one guard bed and can be implemented to completely adsorb the last traces of impurities remaining in the synthesis gas such as halogenated compounds, H2S, COS, HCN and NH3. The final purification step d8) 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).

[0124] Advantageously, at the outlet of step d8), the syngas 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.

[0125] Preferably, step d) comprises, preferably consists of, steps d1) and / or d2) and / or d3) and / or d4) and / or d5) and / or d6) and / or d7) and / or d8).

[0126] Step e) of the Fischer-Tropsch synthesis catalytic reaction

[0127] The process according to the invention comprises a Fischer-Tropsch synthesis step e) of the effluent from gasification step c) and optionally from the conditioning step d) of the gaseous effluent comprising a synthesis gas, and preferably from the final purification step d8, said effluent comprising carbon monoxide (CO) and hydrogen being introduced into synthesis step e) Fischer-Tropsch in the presence of all or part of the hydrogen from step b) of water electrolysis in an optimal H2 / C0 molar ratio for the Fischer-Tropsch reaction so as to produce a stream comprising synthetic liquid hydrocarbons and at least one gaseous effluent.

[0128] Advantageously, step e) of Fischer-Tropsch synthesis is carried out with a molar ratio between carbon monoxide and hydrogen, 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, the hydrogen coming from step d) conditioning of the synthesis gas and step b) of electrolysis of water.

[0129] 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.

[0130] Advantageously, all of the hydrogen from step b) of electrolysis is used in step e) of Fischer-Tropsch synthesis. Optionally, additional hydrogen may be required to obtain an optimal H2 / CO molar ratio for the Fischer-Tropsch reaction. In this case, this additional hydrogen may be obtained from the optional step of carbon monoxide vapor conversion d3).

[0131] Advantageously, said optional step of converting carbon monoxide to steam d3) can be carried out at an absolute pressure of between 2 and 12 MPa, preferably between 2.5 and 6.0 MPa, and more preferably between 3.0 and 5.0 MPa; at an hourly volumetric rate WH (volume of charge / volume of catalyst / hour) of between 1000 and 10000 h-1, preferably between 1000 and 9000 h-1 and more preferably between 1500 and 8500 h-1; at a temperature of between 150 and 550°C, preferably between 200 and 550°C, and more preferably between 250 and 500°C.

[0132] The catalyst used in this step of converting carbon monoxide to steam is a catalyst comprising at least one element from Group VIII and / or at least one element from Group VIB of the Mendeleev periodic table (Group VIII corresponds to Groups 8, 9, and 10, and Group VIB to Group 6 according to the new notation of the periodic table of elements: Handbook of Chemistry and Physics, 81st edition, 2000-2001). Preferably, the catalyst is a catalyst comprising cobalt sulfide and / or molybdenum sulfide. The catalyst support is usually a porous solid selected from the group consisting of aluminas, silica, and silica-aluminas. Preferably, the catalyst support is alumina. The catalyst used may be promoted with an alkali or alkaline earth promoter. The carbon monoxide conversion reaction allows to significantly increase the hydrogen content in the effluent directed to step i) of Fischer-Tropsch synthesis.

[0133] Advantageously, the water formed during step e) of the Fischer-Tropsch synthesis is partly or totally sent to step b) of electrolysis. Recycling the water formed in step e) to step b) reduces the operating costs of the process according to the invention.

[0134] 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).

[0135] 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.

[0136] According to a preferred embodiment of the invention, step e) employs 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.

[0137] 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 said step comprises 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.

[0138] 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.

[0139] According to a variant of the process of the invention, at least a gaseous fraction from the Fischer-Tropsch synthesis (step e) is advantageously recycled in step c) of gasification in order to be converted into synthesis gas and thus improve the mass yield of the process chain.

[0140] In another configuration of the process according to the invention, the gaseous fraction from the Fischer-Tropsch synthesis e) is advantageously at least partly sent to an independent syngas production unit (for example POx: Partial oxidation, SMR: Steam Methane Reforming, ATR: Autothermal Reforming, EHTR: Enhanced Heat Transfer Reformer..), this synthesis gas can be recycled at any point in the chain upstream of step c) of gasification and step f) of hydrotreating and / or isomerization.

[0141] In another configuration of the process according to the invention, at least part of the gaseous fraction from step e) of Fischer-Tropsch synthesis can at least partly supply energy to the drying operations a1) and / or the roasting operations a2) to maximize the energy efficiency of the process chain.

[0142] In another configuration of the process according to the invention, the gaseous fraction from step e) of Fischer-Tropsch synthesis makes it possible to produce electricity in a combined cycle which can be partially powered by the steam produced by steps c), d3) and e) to increase the energy efficiency of the process chain.

[0143] These different configurations can be advantageously combined in order to optimize the economy of the integrated process chain according to the invention.

[0144] f) Hydrotreatment and / or isomerization step

[0145] The process of the invention advantageously comprises a step f) of hydrotreating and / or isomerizing at least a part and preferably all of the stream comprising liquid hydrocarbons from step e) of Fischer-Tropsch synthesis.

[0146] 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 hydrocarbon cuts from step e) by the production of liquid hydrocarbons, in particular liquid biofuels, namely bio-naphtha, bio-gasoline, bio-kerosene, bio-diesel and very high quality bio-lubricating bases.

[0147] The hydrogen required for the implementation of step f) can advantageously come in whole or in part from step b) of water electrolysis.

[0148] 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 of (bio) waxes for various industrial applications. List of figures

[0149] [Fig.1]

[0150] Fig. 1 illustrates the process according to the invention and including the step of isomerizing the effluent from the process according to the invention.

[0151] The biomass is introduced into the pretreatment unit (A) via the pipe 1 in which it undergoes a drying step a1), a roasting step a2) and / or a grinding step a3).

[0152] 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 10 which takes place in the water electrolysis unit (B).

[0153] The water used in the electrolysis unit (B) comes at least in part from the Fisher-Tropsch synthesis step implemented in the unit (E).

[0154] During the water electrolysis step, a flow of hydrogen is produced and sent via the line 8 to the Fischer-Tropsch synthesis step upstream of the unit (E).

[0155] The gasification step of the pretreated biomass, which takes place in unit (C) in the presence of oxygen 11 from the water electrolysis step, produces a gaseous effluent comprising a synthesis gas. This effluent exits the gasification unit (C) via line 3 and is sent to an optional effluent conditioning step (d) containing the synthesis gas. This conditioning step may include a step (d1) of water washing and fractionation of the synthesis gas and / or a step (d2) of removal of halogenated compounds and / or a step (d3) of conversion of carbon monoxide to steam and / or a step (d4) of catalytic hydrolysis of COS and HCN compounds and / or a step (d5) of effluent recombination and / or a step (d6) of water washing of the recombined effluent and / or a step (d7) of acid gas removal and / or a purification step (d8). final effluent including synthesis gas.

[0156] 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) in the presence of at least a portion of the hydrogen stream 8 produced during the water electrolysis step. A stream 6 comprising synthetic liquid hydrocarbons is produced during the Fischer-Tropsch synthesis step and may be sent to a hydrotreating and / or isomerization step f) not shown in the figure.

[0157] [Fig.2]

[0158] Figure 2 illustrates the process according to comparative example 1. The process is described in example 1. Examples

[0159] Example 1 (comparative)

[0160] Example 1 reproduces the process described in application WO2014 / 058253, comprising the following steps:

[0161] A pre-treatment step by roasting.

[0162] An air separation step to produce an oxygen stream.

[0163] A gasification step with entrained flow.

[0164] A step of converting carbon monoxide to steam

[0165] A step of acid gas removal and final purification.

[0166] A Fischer-Tropsch synthesis step.

[0167] The process according to Example 1 is comparative in that it does not involve a water electrolysis step. The process implemented in comparative Example 1 is shown in [Fig. 2].

[0168] Example 1 treats 100 t / h of dry biomass introduced into the pretreatment stage via line 1. The torrefied lignocellulosic biomass exiting pretreatment unit A via line 2 contains 50 wt% carbon and 40% oxygen.

[0169] The torrefied biomass 2 is then introduced into a gasification unit C in the presence of an oxygen flow 7 produced in an air separation unit (B).

[0170] The gasification unit produces 3 times more CO than CO2 in mol, i.e. a quantity of CO of 67.4 t / h. The H2 / CO ratio at the outlet of the gasification unit is 0.5.

[0171] At the outlet of the gasification unit C, an effluent comprising synthesis gas 3 is produced and sent to a unit D for converting carbon monoxide to steam. The carbon monoxide steam conversion unit increases the ratio from 0.5 to 2.

[0172] The effluent 4 exiting the carbon monoxide to steam conversion unit is then sent to a unit (D') comprising a stage for removing acid gases from the effluent including synthesis gas and a final purification stage of said effluent.

[0173] The effluent comprising the purified synthesis gas 5 is then sent to a Fischer-Tropsch synthesis unit € to produce a stream comprising liquid hydrocarbons 6.

[0174] The different steps of the process below result in a reduction in carbon yield:

[0175] The roasting step with a 23% loss of carbon.

[0176] The gasification step with an additional 19% carbon loss

[0177] The step of converting carbon monoxide to vapor with a loss of 29% of additional carbon.

[0178] The carbon loss is calculated according to the following formula: (Center-OutputC) / Center* 100

[0179] The overall carbon yield of the chain is therefore 29 wt%, i.e. a total material yield of 17 wt%.

[0180] The overall carbon yield is calculated according to the following formula: (Cbiomass-CeffluentFT) / Cbiomass* 100.

[0181] The material yield is calculated according to the following formula: (Qbiomass-QeffluentFT) / Qbiomass*100, where Q is the flow rate.

[0182] CO2 is mainly produced in the following two steps:

[0183] The gasification stage represents 35.3 t / h,

[0184] The step of converting carbon monoxide to steam for a flow rate of 88.2 t / h.

[0185] These emissions do not take into account the CO2 emitted for the production of utilities.

[0186] The amount of oxygen required to supply energy to the gasification stage is 46 t / h.

[0187] The Fischer-Tropsch synthesis step allows the production of a synthetic liquid hydrocarbon effluent representing 17 t / h.

[0188] Example 2 (according to the invention)

[0189] Example 2 reproduces a process according to the invention shown in [Fig. 1] and comprising the following steps 1:

[0190] A pre-treatment step a) by roasting.

[0191] A step b) of alkaline electrolysis of water

[0192] A step c) of entrained flow gasification.

[0193] A step d) of conditioning the syngas.

[0194] A Fischer-Tropsch synthesis step e).

[0195] The process of Example 2 according to the invention differs from that of Example 1 in that it implements a step of electrolysis of water and not of conversion to steam of carbon monoxide.

[0196] Example 2 processes 100 t / h of dry biomass via pipe 1 in a torrefaction unit (A). The torrefied lignocellulosic biomass 2 contains 50 wt% carbon and 40 wt% oxygen.

[0197] The torrefied biomass is then sent to a gasification unit C in the presence of an oxygen flow 11 produced in water electrolysis unit (B) 10.

[0198] As in Example 1, the gasification unit produces 3 times more CO than CO2 in mol, i.e., a quantity of CO of 67.4 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 by an external supply of hydrogen produced by alkaline electrolysis.

[0199] The quantity of hydrogen required is 7.2 t / h. To produce such a quantity of hydrogen, the co-product of electrolysis, oxygen, is produced at a rate of 58 t / h. This flow rate is higher than the flow rate required for the gasification step (46 t / h, see previous example).

[0200] An effluent comprising synthesis gas 3 is produced at the outlet of the gasification unit © and sent to a synthesis gas conditioning unit D to produce a purified effluent 5 which is then sent to a Fischer-Tropsch synthesis unit E in the presence of a flow 6 of hydrogen produced in the water electrolysis unit B.

[0201] The different steps of the process leading to the reduction in carbon yield are:

[0202] The roasting step with a 23% loss of carbon.

[0203] The gasification step with an additional 19% carbon loss

[0204] The overall carbon yield of the chain is therefore 58 wt%, i.e. a total material yield of 34 wt%.

[0205] The Fischer-Tropsch synthesis step produces approximately 43 t / h of water, i.e. 66% of the water requirement of the electrolysis step and an effluent of synthetic liquid hydrocarbons representing 34 t / h.

[0206] The amount of CO2 emitted into the atmosphere comes mainly from the gasification stage, i.e. 35.3 t / h. CO2 emissions from the process are reduced by 70% compared to the reference scheme and water consumption by 2 / 3 compared to the consumption required for the electrolyzer, significantly improving the environmental balance of the process.

[0207] Compared to Example 1, the method according to the invention allows

[0208] To increase by 100% the quantity of synthetic hydrocarbons obtained at the end of the Fischer-Tropsch synthesis step,

[0209] To reduce CO2 emissions by the process by 85%

[0210] To reduce water consumption by 2 / 3 compared to the consumption required for the electrolyzer.

[0211] Thus, the process according to the invention makes it possible to significantly improve the environmental balance of the sector and to limit the operating cost of the process.

Claims

Demands

1. A process for converting a feed comprising at least a biomass fraction into hydrocarbons, said process comprising: - a step a) pretreatment of the feed, - a step b) electrolysis of water into oxygen and hydrogen yielding a hydrogen stream and an oxygen stream, wherein the water is derived, at least in part, from a Fischer-Tropsch synthesis step e), - a step c) gasification of the feed pretreated in step a), in the presence of all or part of the oxygen stream from the water electrolysis step b) so as to obtain a gaseous effluent comprising a synthesis gas, - an optional step d) conditioning of the gaseous effluent comprising a synthesis gas from step c) so as to obtain a gaseous effluent comprising a purified synthesis gas,- a Fischer-Tropsch synthesis step (e) of the gaseous effluent from step (c) or possibly step (d) in the presence of all or part of the hydrogen from step (b) of water electrolysis so as to produce a stream comprising synthetic liquid hydrocarbons and at least one gaseous effluent, the molar ratio between hydrogen and carbon monoxide, denoted H2 / CO, of the effluent introduced in step (e) of Fischer-Tropsch synthesis being between 0.5 and 4, - a hydrotreating and / or isomerization step (f) of the hydrocarbon fractions from step (e); wherein at least part of the gaseous fraction from step (e) of Fischer-Tropsch synthesis is recycled in step (c) of gasification in order to be converted into synthesis gas.

2. A process according to claim 1 wherein the pretreatment step a) comprises at least one of the operations of drying a1), roasting a2) or grinding a3).

3. A process according to claim 1 wherein the molar ratio of hydrogen to carbon monoxide, denoted H2 / CO, of the effluent introduced in step e) of the Fischer-Tropsch synthesis is between 1 and 3, more preferably between 1.5 and 2.5, and most preferably equal to 2, the hydrogen originating from step d) of conditioning of the synthesis gas and step b) of water electrolysis.

4. A method according to any one of the preceding claims wherein step b) of electrolysis is carried out by alkaline electrolysis, by proton exchange membrane, by anion exchange membrane, or solid oxide electrolysis.

5. A method according to any one of the preceding claims wherein 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.

6. A process according to any one of claims 1 to 5 wherein all of the oxygen introduced in the gasification step c) is from the water electrolysis step b).

7. A process according to any one of the preceding claims wherein step d) comprises, preferably consists of, steps d1) of water washing and fractionation of the synthesis gas and / or d2) of removal of halogenated compounds and / or d3) of conversion of carbon monoxide to steam and / or d4) of catalytic hydrolysis of the COS and HCN compounds and / or d5) of recombination and / or d6) of water washing of the recombined effluent and / or d7 of removal of acid gases and / or d8) of final purification.

8. A process according to any one of the preceding claims wherein the water formed during step e) of Fischer-Tropsch synthesis is partly or totally sent to step b) of electrolysis.

9. 9. A process according to any one of claims 2 to 8 wherein at least a part of the gaseous fraction from step e) of Fischer-Tropsch synthesis can at least partly supply energy to the drying operations a1) and / or the roasting operations a2).

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