Method for treating biomass by co-grinding with fossil-based feedstock

Abstract

The invention relates to a novel process for treating a feedstock comprising biomass, said process comprising at least the following steps: a) a step of drying said feedstock at a temperature of 20 to 180 DEG C for a duration of 5 to 180 minutes, b) a step of baking the feedstock resulting from step a) to produce at least one baked biomass solids effluent, c) a step of co-grinding the baked biomass solid effluent resulting from step b) in the presence of at least one solid fossil feedstock to obtain a powder.

Description

This application is a divisional application of application number 201880045537.6, and the application date of application number 201880045537.6 is July 3, 2018. Technical Field

[0001] The present invention relates to the treatment of biomass in order to prepare the biomass for the purpose of upgrading it, in particular by gasification, for the production of liquid hydrocarbons and optionally for the production of petrochemical and / or chemical bases and / or hydrogen.

[0002] More particularly, the present invention relates to a method for treating a feedstock comprising biomass with the purpose of injecting it into a gasification reactor in order to produce hydrocarbons, in particular gasoline, gas oil and kerosene. Prior art

[0003] In the field of the present invention, those skilled in the art are constantly seeking to improve the conditioning of biomass, in particular in order to improve its calorific value.

[0004] More particularly, improving the particle size of powders obtained by biomass-based processing methods and the energy costs associated with such processing are fundamental parameters in biomass preparation, especially in the most prevalent gasification process.

[0005] The processing of biomass so as to upgrade the quality of biomass by producing hydrocarbons is well known to those skilled in the art. The main steps of this processing are drying, thermal treatment (such as baking) and grinding. These steps are particularly described in the application WO2014 / 068253. The main parameters of this processing are the characteristics of the powder obtained, in particular its size, and the energy cost of grinding and more generally the process.

[0006] Application WO2013 / 114328 describes a method for grinding a carbonaceous raw material derived from biomass in the presence of an additive in the form of a micron-sized powder, derived from a mineral material (such as magnesium stearate or silicon dioxide, in the form of microbeads) and / or a plant material (such as charcoal or fossil carbon), the purpose of which is to improve the properties of the powder obtained by grinding the biomass, such as flowability and fluidization suitability, thereby allowing to obtain an intimate mixture of powders of small particle size. This document does not describe the use of additives other than those in the form of a powder and having only micron-sized dimensions during the grinding of the biomass.

[0007] Optimizing the treatment and / or conditioning of biomass, in particular by simplifying the processes implemented, reducing the energy costs of said steps, in particular the grinding step, remains a serious challenge in the field of the present invention.

[0008] Surprisingly, the Applicant has found a method for processing a biomass raw material by a step of co-grinding of at least one of said raw materials in a mixture with at least one solid fossil raw material. Advantageously, said co-grinding enables grinding of the raw material as well as drying and grinding of the fossil raw material. In fact, the grinding of the biomass raw material is an exothermic step and the heat generated advantageously allows simultaneous drying of the fossil raw material. Another advantage of the method according to the invention is that the energy costs of the method are reduced by the energy integration of the gases formed during the different steps. Summary of the invention The subject of the present invention is a novel method for processing a raw material comprising biomass, said method comprising at least the following steps: a) a step of drying the raw material at a temperature ranging from 20 to 180° C. for a duration ranging from 5 to 180 minutes, b) a step of torrefying the feedstock originating from step a) to produce at least one torrefied biomass solids effluent, and c) a step of co-grinding the torrefied biomass solid effluent originating from step b) in the presence of at least one solid fossil raw material to obtain a powder, in The residual water content at the end of the drying step a) is between 0% and 5% by weight relative to the total weight of the raw material. The size of the solid fossil raw material introduced in the co-grinding step c) is 1 to 100 mm and preferably 2 to 80 mm, and the solid fossil raw material input into the co-grinding step c) has a moisture content of 3.1 to 30% by weight, preferably 4 to 25% by weight.

[0010] One advantage of the process according to the invention is that it enables an intimate mixture of small-particle-size powders originating from biomass and fossil raw materials to be obtained.

[0011] One advantage of the co-grinding according to the invention is that by transferring the heat energy released by grinding the biomass to the fossil raw material, it enables the fossil raw material to be dried simultaneously with the co-grinding step.

[0012] Another advantage of the present invention is that it enables the processing of biomass at limited energy costs by combining a series of steps operating under specific conditions, allowing their energy integration.

[0013] Preferably, the process comprises a step d) of final drying of the powder obtained at the end of step c) at a temperature ranging from 100 to 300°C.

[0014] Preferably, the drying step d) is carried out simultaneously with the co-grinding step c).

[0015] Preferably, the biomass is selected from any type of biomass, preferably from solid type biomass, in particular from lignocellulosic type biomass. Non-limiting examples of biomass types relate, for example, to residues from agricultural operations (in particular straw, corn cobs), residues from forestry operations, products from forestry operations, residues from sawmills and dedicated crops (e.g. short rotation forests).

[0016] Preferably, the method comprises a step i) of pre-treating the biomass, preferably a primary grinding.

[0017] Preferably, the baking step b) is carried out at a temperature of 200 to 350° C., preferably 220 to 340° C., preferably 250 to 320° C. and more preferably 270 to 300° C., for a duration of 5 to 180 minutes and preferably 15 to 60 minutes, at an absolute operating pressure of preferably 0.1 to 15 bar, preferably 0.1 to 10 bar and more preferably 0.5 to 1.5 bar.

[0018] Preferably, the method comprises a step ii) of combusting the torrefaction gases (11) originating from step b).

[0019] Preferably, the energy of step ii) originating from the combustion of the torrefaction gases (11) is used in order to provide the thermal energy required in the steps of the method, preferably steps a), b) and / or d).

[0020] Preferably, the solid fossil feedstock (9) introduced in the co-grinding step c) is selected from solid fossil hydrocarbons, such as coal, petroleum coke, tanker residues, tar sands or derivatives thereof, and oil shale or derivatives thereof.

[0021] Preferably, the solid fossil raw material (9) is subjected to a preliminary drying step iii).

[0022] Preferably, the torrefied biomass solid effluent originating from step b) is introduced in the co-grinding step c) in an amount of 1 to 99 wt. %, preferably 50 to 98 wt. % and preferably 40 to 95 wt. % of the torrefied biomass solid effluent in the total solid raw material, the total solid raw material being the sum of the torrefied biomass solid effluent and the fossil raw material.

[0023] Preferably, the solid fossil raw material fed to the co-grinding step c) has a moisture content of 5 to 20% by weight.

[0024] Preferably, the process comprises one or more steps e) of storing effluent originating from one or any step of the process, preferably from step a), b), c) or d).

[0025] Preferably, the method comprises a step f) of conveying, preferably pneumatic conveying.

[0026] Preferably, the process comprises a step g) of gasification at a temperature ranging from 800 to 1800° C., preferably from 1000 to 1600° C. and more preferably from 1200 to 1500° C. and at an absolute pressure advantageously ranging from 20 to 120 bar, preferably from 25 to 60 bar and more preferably from 30 to 50 bar.

[0027] Definitions and Abbreviations Throughout the specification as a whole, the following terms or abbreviations have the following meanings.

[0028] Biomass refers, without limitation, to materials from solid types of biomass, in particular from lignocellulosic types of biomass. Non-limiting examples of biomass types relate, for example, to residues from agricultural operations (in particular straw, corn cobs), residues from forestry operations, products from forestry operations, residues from sawmills, and specialized crops (e.g. short rotation forests).

[0029] Solid fossil materials refer, without limitation, to materials which are solid under the conditions of the grinding step, either alone or in mixture, and are selected from solid fossil hydrocarbons such as coal, petroleum coke, tanker residues, tar sands or derivatives thereof, and oil shale or derivatives thereof.

[0030] The water-free weight loss refers to the percentage of material lost during the baking step (excluding water) compared to the total weight injected during the baking step (excluding water).

[0031] Baking refers to a heat treatment process performed at a temperature of 200 to 350° C. and usually in an oxygen-deficient atmosphere.

[0032] Gasification refers to the step of carrying out a partial oxidation reaction which converts the feedstock into a synthesis gas containing mostly carbon monoxide and hydrogen.

[0033] Co-grinding refers to the grinding of biomass feedstock in the presence of solid fossil feedstock.

[0034] Relationship or weight ratio refers to the ratio between the weight of the relevant ingredients relative to the total weight of the raw materials.

[0035] Characteristic size refers to the length measurement of a particle along its longest dimension.

[0036] Anisotropy refers to the ability of a material to have varying strength properties depending on the orientation of the forces to which it is subjected.

[0037] Moisture content refers to the ratio between the weight of water contained in a raw material and the total weight of the raw material. DETAILED DESCRIPTION The various embodiments presented can be used alone or in combination with one another within the meaning of the present invention, without any restrictions on the combinations.

[0039] raw material According to the present invention, the raw material of the method comprises biomass alone or in a mixture. The amount of water contained in the raw raw material is 0.0 to 70.0% by weight, preferably 5.0 to 70.0%, preferably 10.0 to 70.0%.

[0040] The biomass is selected from any type of biomass, preferably from solid type biomass, in particular from lignocellulosic type biomass. Non-limiting examples of biomass types relate, for example, to residues from agricultural operations (in particular straw, corn cobs), residues from forestry operations, products from forestry operations, residues from sawmills and dedicated crops (e.g. short rotation budding forests).

[0041] Preferably, the biomass is lignocellulosic biomass. It essentially comprises three natural components present in variable amounts depending on its origin: cellulose, hemicellulose and lignin.

[0042] The lignocellulosic biomass feedstock is preferably used in its original form, ie in its entirety of its three components, cellulose, hemicellulose and lignin.

[0043] In a preferred embodiment of the invention the lignocellulosic biomass is selected from grass biomass, residues from agricultural operations such as waste straw, corn cobs, shredded sugar cane stalks, residues from forestry operations or from sawmills such as wood chips or other types of woody residues.

[0044] In a preferred embodiment of the present invention, the feedstock (1) may optionally undergo a pretreatment step i) before introducing it into step a) of the process according to the present invention. The purpose of the pretreatment step i) is to allow the pretreated feedstock (2) to be fed into the drying step a).

[0045] The pretreatment step i) varies with the type of raw material concerned. Preferably, the pretreatment step i) is a preliminary grinding step of said raw material, which makes it possible to reduce its particle size to a characteristic size of 10 to 50 mm. Said preliminary grinding step i) is advantageously carried out according to techniques known to those skilled in the art. The pretreatment step i) may also advantageously comprise shaping the raw material, for example by granulation, compression or any other technique known to those skilled in the art, in order to facilitate its transport, storage and subsequent treatment in the drying step a) of the process according to the invention.

[0046] Drying step a) According to the invention, the method comprises a step a) of drying the raw material (1), optionally pretreated (2), said drying step a) being carried out by contacting the raw material with a hot gas stream, said hot gas stream reducing the temperature. The hot gas stream enters said step at a temperature of 50 to 500° C., preferably 100 to 450° C., and preferably 150 to 350° C., for a duration of 5 to 180 minutes, preferably 10 to 100 minutes, and preferably 15 to 60 minutes, and provides a dried and optionally pretreated raw material (3). The dried solid leaves said step at a temperature of 40 to 120° C., preferably 50 to 90° C., and even more preferably 60 to 80° C.

[0047] The purpose of drying is to eliminate the water contained in the raw material. According to the invention, the residual water content at the end of drying step a) is between 0% and 5% by weight relative to the total weight of the raw material.

[0048] The energy required for drying is usually provided by contacting the feedstock with a stream of hot gas.

[0049] The hot gas stream used for the drying step can advantageously originate from the combustion of an input to the process, preferably from the combustion of natural gas and / or from the combustion of a gas stream produced in another step of the process.

[0050] For example, the combustion of the gases originating from the torrefaction step b) generates a hot gas stream which can be used to dry the feedstock by any method known to those skilled in the art.

[0051] The gaseous effluent containing water originating from step a) can be used to preheat the air enabling the combustion of the natural gas and / or the gas stream generated during the torrefaction process.

[0052] In a particular embodiment, said feedstock (1) introduced in step a) consists of biomass as defined above.

[0053] Baking step b) According to the invention, the dried feedstock (3) originating from step a) is sent to a torrefaction step b) to produce at least one torrefied biomass solid effluent (4).

[0054] Torrefaction is a process of mild thermal decomposition in the temperature range of 200 to 350° C. The process is usually characterized by low temperature gradients (<50° C. / min) and long residence times (20 to 60 min).

[0055] According to the invention, the baking step b) is carried out for a duration of 5 to 180 minutes, preferably 15 to 60 minutes, at an absolute operating pressure of preferably 0.1 to 15 bar, preferably 0.1 to 10 bar and more preferably 0.5 to 1.5 bar (1 bar = 0.1 MPa), at a temperature of 200 to 350° C., preferably 220 to 340° C., preferably 250 to 320° C. and more preferably 270 to 300° C. The baking operation is carried out in an environment whose oxygen content is less than 10% by volume, preferably 0 to 10% by volume, preferably 0 to 8% by volume and preferably 0 to 3% by volume.

[0056] At about 200°C, hemicellulose, the most reactive compound of lignocellulosic biomass, begins to undergo devolatilization and carbonization reactions. At this temperature level, cellulose and lignin are not significantly converted by themselves. The decomposition products of lignocellulosic biomass are produced in the form of condensable gases (mainly water, formic acid, acetic acid and other organic compounds) and non-condensable gases (mainly CO and CO2).

[0057] Baking changes the structure of lignocellulosic biomass, and thus changes its properties. In particular, the baking operation makes biomass more fragile, and weakens its highly anisotropic properties. It is well known to those skilled in the art that, for example, wood has a much higher elastic tensile resistance in the fiber direction than the elastic tensile resistance when horizontally applied stretching due to its fiber properties. Therefore, compared with the coarse biomass powder with a given average particle size, obtaining a comparable powder based on the same biomass that has undergone a baking step will require much lower grinding energy (effects associated with the brittleness of the material), and the final form of the solid particles obtained is closer to spherical particles (effects associated with smaller anisotropic properties), which is conducive to subsequent grinding.

[0058] Said baking step b) can advantageously be carried out in apparatuses of the rotary kiln, rotary calciner kiln, screw conveyor kiln, moving bed kiln and fluidized bed kiln type.

[0059] According to the invention, the torrefaction step b) produces a solid effluent called torrefied biomass (4).

[0060] Said torrefaction step b) also allows the production of a combustible gaseous effluent (8) called torrefaction gases, the amount of which preferably represents from 5 to 40% and more preferably from 10 to 35% by weight of the dried biomass originating from the initial step a), depending on the operating conditions.

[0061] One of the key parameters of the torrefaction step is the weight loss (expressed as a percentage by weight), which is defined as the percentage weight loss between the initial dry biomass and the dried torrefied biomass. The higher this loss, the lower the solid mass yield by weight and the greater the amount of torrefaction gas generated. It is known that the lower heating value (LCV) of the gas also changes with the anhydrous weight loss percentage (for a given feedstock, the AWL is an increasing function of this percentage).

[0062] According to the invention, the choice of a sufficiently high percentage of anhydrous weight loss during the torrefaction step makes it possible to limit the consumption of input fuels in the process, in particular during the drying process. It thus limits the use of fuels of fossil origin by reusing the torrefaction gases generated during the torrefaction step.

[0063] In a preferred embodiment, the anhydrous weight loss percentage is selected so that the heat released by the combustion of the torrefaction gases (after internal or external combustion) can provide the energy required for at least one drying step. Preferably, the anhydrous weight loss is between 1.0 and 40.0% by weight, preferably between 5.0 and 35.0% by weight and preferably between 15.0 and 30.0% by weight relative to the total weight of the feedstock (3) introduced into the torrefaction step b).

[0064] In one embodiment of the process, the torrefaction gases (11) are sent to a combustion step ii) where they are combusted in the presence of air and optionally natural gas to produce in a combustion chamber a hot gas stream (12) that can be sent to drying steps a) and / or d), or a hot gas stream (13) that can be sent to a torrefaction step b). The combustion step ii) can advantageously be integrated with the torrefaction step b) or not.

[0065] In one embodiment, the energy generated during step ii) of combustion of the torrefaction gases (11) originating from step b) is used in order to provide the energy required for at least one step of the process, preferably the drying step a), and preferably also for the final drying step d) using stream (12) or for the torrefaction step b) using stream (13).

[0066] The thermal energy originating from the combustion step ii) is fed to steps a), b) and / or d) by means known to the person skilled in the art.

[0067] It may be advantageous to send part of the hot gas stream ( 12 ) originating from the combustion step ii) to a heat exchange step, making it possible to preheat the air used in the drying step a) and in the final drying step d).

[0068] In one embodiment, a portion of the hot gas stream (13) originating from the combustion step ii) is directly injected into the torrefaction step b) in order to provide the energy required for the conversion of the biomass feedstock by gas / solid heat exchange.

[0069] If the flow of combustible torrefaction gas originating from step b) is insufficient, fuel and preferably natural gas may advantageously be added by introduction in the combustion step ii) in order to obtain the energy required for the different steps consuming thermal energy.

[0070] At the end of the torrefaction step b), the obtained torrefied biomass solid effluent (4) has a moisture content of 0.0 to 5.0 wt.-%, preferably 0.0 to 3.0 wt.-%.Torrefied biomass solids refer to solids obtained by torrefying biomass.

[0071] The torrefied biomass solids (4) obtained at the end of step b) can optionally be stored in an optional storage step before being introduced into the co-grinding step c) of the method according to the invention. Said storage step can advantageously be carried out according to methods known to those skilled in the art. Preferably, the torrefied solid biomass can be stored in a tank with a screw conveyor, in a silo or under a hanger in a suitable open room.

[0072] In the advantageous case where the co-grinding step c) is carried out sequentially, the storage step enables the roasting step b) and the optional combustion step ii) to be continued in order to continue to generate the hot gas flow (12) required for the drying step a) and the final drying step d).

[0073] Co-grinding step c) According to the invention, the method comprises a step c) of co-grinding the torrefied biomass solid effluent (4) originating from step b) and optionally having been stored in an optional storage step, in the presence of at least one solid fossil raw material (9), so as to obtain a ground effluent (5), also referred to as ground powder (5). The co-grinding step c) is carried out at a temperature of 0° C. to 150° C., preferably 20° C. to 100° C. and also preferably 50° C. to 90° C. The solid fossil raw material (9) and the torrefied biomass solid (4) are ground simultaneously in the same mill.

[0074] The purpose of the co-grinding step c) is to reduce the particle size of the two raw materials (4) and (9) introduced in said step c) while providing a particle shape suitable for subsequent transport and use thereof and preferably for their injection into the gasification step. The particles of the effluent (5) have a characteristic size of 50 to 200 microns, preferably 70 to 200 microns and preferably 80 to 150 microns at the end of said co-grinding step c).

[0075] The solid fossil raw material (9) introduced in the co-grinding step c) is preferably selected from solid fossil hydrocarbons, such as coal, petroleum coke, tanker residues, tar sands or derivatives thereof, and oil shale or derivatives thereof.

[0076] The size of the solid fossil raw material introduced in the co-grinding step c) is preferably from 1 to 100 mm, preferably from 2.0 to 80 mm, preferably from 3.0 to 70 mm, preferably from 4.0 to 60 mm and preferably from 5 to 50 mm.

[0077] In a particular embodiment, the fossil raw material may have a size of 30 to 100 mm, preferably 35 to 90 mm, preferably 40 to 80 mm and preferably 45 to 70 mm.

[0078] In another particular embodiment, the fossil raw material may have a size of 1.0 to 60 mm, preferably 2.0 to 50 mm, preferably 3.0 to 40 mm and preferably 4.0 to 30 mm.

[0079] Preferably, the solid fossil raw material (9) may be subjected to an optional comminution step in order to reduce the size of said raw material and allow its introduction into the co-grinding step c).

[0080] The solid fossil raw material (9) may advantageously undergo a preliminary drying step iii) depending on its initial moisture content before its introduction into said co-grinding step c). The preliminary drying step iii) makes it possible to obtain a pre-dried fossil raw material (10) and make it compatible with its injection into the co-grinding step c).

[0081] Preferably, the moisture content of the fossil raw material (9) or (10) fed into the co-grinding step c) must be from 3.1 to 30.0% by weight, preferably from 4.0 to 25.0% by weight and very preferably from 5.0 to 20.0% by weight.

[0082] Preferably, the torrefied biomass solid effluent (4) and the solid fossil raw material (9) or (10) are introduced into the co-grinding step c) so that the weight percentage between the torrefied biomass solid effluent and the total solid raw material supplied to the co-grinding step c) is 1 to 99 wt. %, preferably 50 to 98 wt. %, preferably 40 to 95 wt. %. The solid raw material refers to the sum of the torrefied biomass solids (4) and the fossil raw material (9) or (10).

[0083] Preferably, the co-grinding step can be carried out in the presence of additional compounds useful for the subsequent gasification step, selected from vitrified ash, sand, limestone, lime or other compounds known to those skilled in the art, used alone or in a mixture.

[0084] Preferably, the mill is chosen so as to optimize the pneumatic conveying of the powder (5) obtained from step c), minimizing the minimum fluidization velocity (MFV) and its own energy consumption.

[0085] Preferably, said co-grinding step c) is carried out in a mill of the "roller mill", "universal grinder" or "attritor mill" type or any other type of mill known to a person skilled in the art.

[0086] Surprisingly, the applicant has noticed that, in addition to the grinding of the solid fossil raw material (9) or (10), the co-grinding of the torrefied biomass solids (4) and the solid fossil raw material (9) or (10) also leads to a particularly effective drying of the raw material (9) or (10). In fact, grinding is a highly exothermic step. In addition, the embodiment as described in accordance with the invention makes it possible to obtain an intimate mixture of the two types of raw materials. Therefore, the co-grinding of a not very moist raw material (such as a torrefied biomass solid effluent) with a moist raw material (such as a solid fossil raw material) allows the heat generated by the grinding of the biomass to be transferred to the water contained in the moist solid fossil raw material, and thus optimizes its drying. This simultaneous drying advantageously makes it possible to simplify the number of steps of the method and limit its energy consumption.

[0087] Optional final drying step d) Preferably, the process according to the invention may comprise a final drying step d) of the powder (5) obtained at the end of step c). This final drying step d) is carried out by contacting the raw material with a gas stream. The gas stream enters the step at a temperature ranging from 50 to 150° C., preferably from 70 to 120° C., to produce a dried powder (6).

[0088] The purpose of the optional final drying step d) is to reduce the moisture content of the powder (5) originating from step c) to an acceptable level in order to feed it into a subsequent treatment step, preferably a gasification step. Preferably, the optional final drying step d) makes it possible to reduce the moisture content of the powder obtained at the end of step c) to less than 3.0% by weight, preferably between 1.0 and 3.0% by weight.

[0089] Preferably, the final drying step d) is carried out simultaneously with the co-grinding step c).

[0090] The thermal energy required for this drying is provided by the combustion of a stream input to the process (for example natural gas) or preferably by energy integration achieved by means of heat exchange by preheating the drying air using the hot effluent (12) from the combustion step ii). According to the invention, the choice of a sufficiently high percentage of anhydrous weight loss in the torrefaction step b) makes it possible to limit the use of input fuels during step d); in particular, it limits the use of fuels of fossil origin.

[0091] Optional storage step e) The method according to the invention may advantageously comprise one or more steps e) of storing the effluent originating from one or more steps of the method, preferably steps a), b), c) or d). Preferably, the effluent originating from step c) or d) is stored to produce a stored effluent (7), also called stored powder (7).

[0092] The storage makes it possible to keep a buffer of raw materials which is necessary to maintain the ability to operate the downstream section in the event of a stoppage of the upstream section.

[0093] The storage step e) preferably consists of silos with sufficient available volume to ensure the supply of the downstream stages. For example, the volume of these silos must provide a 24 to 48 hour supply to the downstream stages.

[0094] The storage step e) may also comprise a pressurization system by means of a plurality of consecutive tanks operated in sequence so as to increase the storage pressure of the feedstock until a pressure compatible with its injection into a subsequent step, preferably into the gasification step, is reached.

[0095] Optional conveying step f) The effluent (5) originating from step c) or the effluent (6) originating from step d) or the effluent (7) originating from the storage step e) can advantageously be subjected to a conveying step f). The effluent conveyed in this way is referred to as conveyed effluent (8) or also as conveyed powder (8). The conveying step f) enables the effluent (5), (6) or (7), preferably formulated and having the desired composition, to be conveyed to a subsequent step and preferably to a gasification step g).

[0096] Preferably, the conveying step f) is performed according to pneumatic conveying technology.

[0097] The carrier gas used in step f) of transferring by pneumatic conveying is preferably nitrogen, carbon dioxide or any other inert gas which makes it possible to avoid the formation of areas with explosive atmospheres (ATEX powders) and is compatible with the subsequent steps situated downstream and preferably with the gasification step g).

[0098] The carrier gas is calculated according to methods known to those skilled in the art to obtain the desired delivery flow and delivery density. The parameters of the roasting step b) and the co-grinding step c) are selected to optimize the quality of the delivery (MFV according to energy-optimized MFV of these stages).

[0099] Optional gasification step g) The powder originating from step c), d) or from the storage step e) is conveyed to step f), and the powder, preferably formulated and having the desired composition, can advantageously be conveyed to the subsequent gasification step g).

[0100] The gasification step g) is carried out in a partial oxidation reaction which converts the feedstock into a synthesis gas containing a major part of carbon monoxide and hydrogen. The gasification step g) is advantageously operated in the presence of a controlled amount of oxygen in the form of a stream of which the flow rate is controlled and which contains at least 90% by volume of oxygen, preferably at least 96% by volume of oxygen.

[0101] The gasification step g) of the effluent ( 8 ) is advantageously carried out according to methods known to those skilled in the art.

[0102] Preferably, it is carried out in a gasifier of fixed bed or fluidized bed type, or preferably in an entrained flow gasifier with cooled walls, at high temperatures, i.e. at temperatures ranging from 800 to 1800° C., preferably from 1000 to 1600° C. and more preferably from 1200 to 1500° C. and at an absolute pressure advantageously ranging from 2 to 12 MPa, preferably from 2.5 to 6 MPa and more preferably from 3 to 5 MPa. High temperatures enable high carbon conversions to be obtained and therefore reduce the amount of unconverted carbon in the ash produced, thereby reducing the amount of ash recycled to the gasifier.

[0103] In a particular embodiment of the invention, the process comprises steps a), b) and c), or steps a), b), c) and d), or steps a), b), c), d) and e), or steps a), b), c), d), e) and f), or steps a), b), c), d), e), f) and g).

[0104] In a specific embodiment of the invention, the process consists of steps a), b) and c), or steps a), b), c) and d), or steps a), b), c), d) and e), or steps a), b), c), d), e) and f), or steps a), b), c), d), e), f) and g). BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 The general layout of the prior art process implemented in Example 1 is shown. The processing of biomass and solid fossil feedstock is carried out independently until their injection into the optional gasification step g).

[0106] Before introducing it into step a), the biomass raw material (I) may undergo a pretreatment step i). During step a), the pretreated biomass raw material (II) or the biomass raw material (I) is dried to produce a dried biomass raw material (III), also referred to as effluent (III). The effluent (III) derived from step a) is then baked in step b). The baking step b) produces a solid effluent (IV) called baked biomass. The baked biomass solid effluent (IV) derived from step b) is then ground in step c). The powder (V) derived from the co-grinding step c) may optionally be dried in the final drying step d). The powder (V) derived from step c) or the powder (VI) derived from step d) may undergo a storage step e). The stored powder (VII) or the ground powder (V) or the dried powder (VI) may participate in the conveying step f). The powder (VIII) thus conveyed may participate in the gasification step g).

[0107] In step c') the solid fossil raw material (IX) is ground. The powder (X) from the grinding step c') is dried during a final drying step d') to produce a dried powder (XI). The powder (XI) from step c') undergoes a storage step e'). The stored powder (XII) or the dried powder (XI) or the ground powder (X) participates in a conveying step f'). The powder (XIII) thus conveyed can participate in a gasification step g).

[0108] Figure 2The general layout of the method according to the invention implemented in Example 2 is shown. Before it is introduced into step a), the biomass raw material (1) may undergo a pretreatment step i). During step a), the pretreated biomass raw material (2) or the biomass raw material (1) is dried to produce a dried biomass raw material (3), also referred to as effluent (3). The effluent (3) derived from step a) is then baked in step b). The baking step b) produces a solid effluent (4) called baked biomass. The baked biomass solid effluent (4) derived from step b) is then co-grinded in the presence of at least one solid fossil raw material (9) in step c) to obtain a powder. Before it is introduced into the co-grinding step c), the solid fossil raw material (9) may undergo a preliminary drying step iii) so that a pre-dried fossil raw material (10) can be obtained. The powder (5) derived from the co-grinding step c) may optionally be dried during the final drying step d). The co-grinded powder (5) derived from step c) or the dried powder (6) derived from step d) may undergo a storage step e). The stored powder (7) or the ground powder (5) or the dried powder (6) can participate in the conveying step f). The powder (8) thus conveyed can participate in the gasification step g). The torrefaction gases (11) originating from the torrefaction step b) are sent to the combustion step ii), where they are burned to produce a hot gas stream (12) that allows heating the drying step a) directly or indirectly via a heat exchanger. The gases originating from the combustion step ii) are also burned to produce a hot gas stream (13) that is sent to the torrefaction step b).

[0109] Figure 3 The general layout of the method according to the invention implemented in Example 3 is shown. The method is a variant of the method implemented in Example 2, additionally comprising the integration of energy into the final drying step d). In this variant, the torrefaction gases (12) allow heating of the final drying step d) directly or indirectly via a heat exchanger.

[0110] The following examples illustrate the invention without limiting its scope. Example

[0111] Example 1: Method without co-grinding (according to the prior art) Figure 1 The general layout of the prior art method according to Example 1 is shown.

[0112] According to this embodiment, the method allows processing of 2 raw materials: A feedstock A of lignocellulosic biomass type in the form of oak wood chips with a characteristic size of 20 to 30 mm. The moisture content of this feedstock was 30% by weight. • Raw material B of fossil (coal) type, in the form of particles with a characteristic size ranging from 5 to 50 mm.

[0113] The method has no co-grinding step between the production line for preparing raw material A and the production line for preparing raw material B, and no energy integration step.

[0114] The method for treating the raw material A has energy-integrated steps from the roasting step b) to the step a) of drying the raw material.

[0115] The goal of the process is to prepare 1 ton of feedstock per hour for the downstream process (here the gasification process). The resulting feedstock must consist of 75% dry and ash-free (DAF) biomass and 25% DAF fossil feedstock.

[0116] Description of the production line used to prepare raw material A: Raw material A was sent to a drying step, which reduced the moisture content of the raw material to 3% by weight. The temperature of the solids at the end of the drying step was 70°C. The dried wood chips were sent to a torrefaction step operated at an average temperature of 300°C. The water-free weight loss during the torrefaction step was 27%. The residual moisture of the wood chips at the end of this step was considered to be zero.

[0117] The dried and torrefied wood chips are sent to a grinding step, wherein the technology is known to those skilled in the art, for example a technology of the roller mill type. This step enables the particle size of the majority (90% of the particles) to be reduced to less than 90 microns. The technology used for particle size characterization uses sieves according to standard NF EN 933.

[0118] According to the present embodiment, there is no step called final drying step; the raw material A in powder form, dried and roasted, is sent to a storage step by dilute phase pneumatic conveying and then to a pneumatic conveying step so that it can be injected into the downstream gasification process. The pneumatic conveying is carried out in dense phase. The dense phase pneumatic conveying step is carried out with an inert carrier gas, which in the present embodiment is nitrogen.

[0119] Description of the production line for preparing raw material B: Raw material B is sent directly to a grinding step, the technology of which is known to those skilled in the art, for example that of the centrifugal roller mill type (for comminution). This step makes it possible to reduce the particle size of the majority (90% of the particles) to less than 90 microns. The technology used for particle size characterization uses sieves according to standard NF EN 933. Simultaneously with the grinding step, the raw material undergoes a final drying step that makes it possible to bring its moisture content to 3% by weight. This final drying step is implemented by using a natural gas burner that heats the gas stream that is in direct contact with the raw material during the grinding process in order to dry it.

[0120] The raw material B in the form of dried powder is fed to a storage step by dilute phase pneumatic conveying and then to a pneumatic conveying step so that it can be injected into the downstream gasification process. The pneumatic conveying is carried out in dense phase. The dense phase pneumatic conveying step is carried out using nitrogen as an inert carrier gas.

[0121] The following table gives the utility consumption for this layout:

[0122] The electricity consumed includes the electricity required for grinding in the centrifugal mill.

[0123] The natural gas consumed corresponds to the primary drying step and the final drying step.

[0124] Nitrogen meets the requirements for pneumatic conveying and ventilation in silos.

[0125] Example 2: Process with co-grinding and without integrating energy into the step (according to the invention) Figure 2 The layout of the method according to the invention implemented in Example 2 is shown.

[0126] According to this embodiment, the method allows processing of two feedstocks: A feedstock A of lignocellulosic biomass type in the form of oak wood chips with a characteristic size of 20 to 30 mm. The moisture content of this feedstock was 30% by weight. • Raw material B of fossil (coal) type, in the form of particles with a characteristic size ranging from 10 to 30 mm.

[0127] The process has a co-grinding step between the line for preparing raw material A and the line for raw material B, and without any energy integration into the drying step d). The co-grinding step and the final drying step are carried out simultaneously.

[0128] The heat originating from the combustion of the torrefaction gases is used in the torrefaction step b) and in the drying step a).

[0129] The process aims to prepare 1 tonne of feedstock per hour for the downstream gasification process. The generated feedstock must consist of 75% dry and ash-free (DAF) biomass and 25% DAF fossil feedstock.

[0130] Description of the production line for preparing mixed raw materials: Raw material A was sent to a drying step, which reduced the moisture content of the raw material to 3% by weight. The temperature of the solids at the end of the drying step was 70°C. The dried wood chips were sent to a torrefaction step operated at an average temperature of 300°C. The water-free weight loss during the torrefaction step was 27%. The residual moisture of the wood chips at the end of this step was negligible and considered to be zero.

[0131] The dried and roasted wood chips are sent to a co-grinding step, the technology of which is known to those skilled in the art, for example the technology of the centrifugal roller mill type. Raw material B is conveyed directly into the same mill. This step makes it possible to reduce the particle size of the majority (90% of the particles) to less than 90 microns. The technology used for particle size characterization uses sieves according to standard NF EN 933.

[0132] According to this embodiment, the mixture of raw materials undergoes a drying step d) at the same time as the grinding step. An unexpected effect of this grinding-drying in the mixture is the reduction of the energy required for drying the raw material B. In fact, the grinding of the raw material A is exothermic and generates heat for drying the raw material B. The heat generated by grinding A makes it possible to significantly reduce the energy consumed for drying. This effect is reflected in the natural gas consumption of the burner, which increases the temperature of the burner atmosphere. The mixture of raw material A and raw material B in the form of dried powders resulting from grinding is sent to a storage step by dilute phase pneumatic conveying and then to a pneumatic conveying step, making it possible to inject it into the downstream gasification process. Pneumatic conveying is carried out in dense phase here. The dense phase pneumatic conveying step is carried out here with an inert carrier gas, which in this embodiment is nitrogen.

[0133] The following table gives the utility consumption for this layout:

[0134] The electricity consumed includes the electricity required for grinding in the centrifugal mill.

[0135] The natural gas consumed corresponds to the final drying step d).

[0136] Nitrogen meets the requirements for pneumatic conveying and ventilation in silos.

[0137] Example 3: Process with co-grinding and energy integration into the final drying step d) (according to the invention) Figure 3 The layout of the method according to the invention implemented in Example 3 is shown.

[0138] The process has a co-grinding step between the production line for raw material A and the production line for raw material B, thus allowing the two raw materials to be processed on the same production line. Furthermore, the process has an energy integration for the final drying step d).

[0139] The co-grinding step and the final drying step are carried out simultaneously.

[0140] The characteristics of raw materials A and B used in this process are the same as those of raw materials A and B used in Example 2.

[0141] The heat originating from the combustion of the torrefaction gases is used in the torrefaction step b) and in the drying step a).

[0142] The advantage of the method implemented in this example is the energy integration from the roasting step to the final drying step of the raw material mixture powder. In this case, the water-free weight loss is about 28%, and advantageously enables the generation of the heat required for the final drying.

[0143] The energy integration, also referred to as heat integration, takes place here indirectly via the use of heat exchangers.

[0144] The following table gives the utility consumption for this layout:

[0145] The electricity consumed includes the electricity required for grinding in the centrifugal mill.

[0146] The natural gas consumed corresponds to the final drying step d).

[0147] Nitrogen meets the requirements for pneumatic conveying and ventilation in silos.

[0148] These examples clearly show that the co-grinding of raw materials A and B (Example 2) makes it possible to significantly reduce the consumption of natural gas from 130 (Example 1) to 109 MJ / h. In addition, the integration of energy into the final drying step d) (Example 3) makes it possible to be autothermal, i.e. without the need for an external energy supply. For a throughput of 1.0 t / h, the raw material flow rate input into the process is then 1.04 t / h. The corresponding water-free weight loss thus makes it possible to generate the heat required for the thermal integration of the roasting with the final drying of the raw materials.

Claims

1. A method for processing a feedstock comprising solid biomass, the method comprising at least the following steps: a) a step of drying the raw material at a temperature ranging from 20 to 180° C. for a duration ranging from 5 to 180 minutes, b) a step of torrefying the dried feedstock originating from step a) to produce at least one torrefied biomass solid effluent, and c) a step of co-grinding said at least one torrefied biomass solid effluent originating from step b) in the presence of at least one solid fossil feedstock to obtain a powder, in The residual water content at the end of the drying step a) is 0.0% to 5.0% by weight relative to the total weight of the raw material, The size of the solid fossil raw material introduced in the co-grinding step c) is 1 to 100 mm and preferably 2.0 to 80 mm or 3.0 to 70 mm, The solid fossil raw material fed to the co-grinding step c) has a moisture content of 3.1 to 30.0% by weight, preferably 4.0 to 25.0% by weight or 5.0 to 20.0% by weight, as well as Step d) of drying the powder obtained at the end of step c) is carried out simultaneously with said co-grinding step c).

2. The method according to claim 1, wherein the biomass is selected from solid lignocellulosic type biomass.

3. The method according to any one of the preceding claims, comprising a step i) of pre-treatment of the biomass, preferably primary grinding.

4. The method according to any one of the preceding claims, wherein the baking step b) is carried out at a temperature of 200 to 350° C., preferably 220 to 340° C., preferably 250 to 320° C. and more preferably 270 to 300° C. for a duration of 5 to 180 minutes and preferably 15 to 60 minutes at an absolute operating pressure of preferably 0.1 to 15 bar, preferably 0.1 to 10 bar and more preferably 0.5 to 1.5 bar.

5. The method according to any of the preceding claims, comprising a step ii) of combusting the torrefaction gases (11) originating from step b).

6. The method according to any of the preceding claims, wherein the energy of step ii) originating from the combustion of torrefaction gases (11) is used in order to provide the thermal energy required in the steps of the method, preferably steps a), b) and / or d).

7. A method according to any one of the preceding claims, wherein the solid fossil raw material (9) introduced in the co-grinding step c) is selected from solid fossil hydrocarbons such as coal, petroleum coke, tanker residues, tar sands or derivatives thereof, and oil shale or derivatives thereof.

8. The method according to any of the preceding claims, wherein the solid fossil raw material (9) is subjected to a step iii) of preliminary drying.

9. A method according to any of the preceding claims, wherein the torrefied biomass solid effluent from step b) is introduced in the co-grinding step c) at a weight percentage of 50 to 98 wt. % or 40 to 95 wt. % of the torrefied biomass solid effluent in the total solid raw material, the total solid raw material being the sum of the torrefied biomass solid effluent and the fossil raw material.

10. The method according to any of the preceding claims, wherein the solid fossil raw material input to the co-grinding step c) has a moisture content of 5.0 to 20.0% by weight.

11. The method according to any of the preceding claims, comprising one or more steps e) of storing effluent originating from one or some steps of the method, preferably from steps a), b), c) or d).

12. The method according to any of the preceding claims, comprising a step f) of conveying, preferably pneumatic conveying.

13. The process according to any one of the preceding claims, comprising a step g) of gasification at a temperature ranging from 800 to 1800°C, preferably from 1000 to 1600°C and more preferably from 1200 to 1500°C and at an absolute pressure advantageously ranging from 2 to 12 MPa, preferably from 2.5 to 6 MPa and more preferably from 3 to 5 MPa.

14. A method according to any one of the preceding claims, wherein: During step b) of roasting the dried raw material from step a), the water-free weight loss of the raw material is between 1.0% and 40.0% by weight, preferably between 5.0% and 35.0% by weight and in particular between 15.0% and 30.0% by weight relative to the total weight of the raw material introduced in said roasting step b).

15. The method according to any one of the preceding claims, according to which the co-grinding step c) is carried out in the presence of an additional compound selected from vitrified ash, sand, limestone or lime, used alone or in a mixture.

16. The method according to any of the preceding claims, according to which the torrefied biomass solid effluent (4) obtained at the end of torrefaction step b) has a moisture content of 0.0% to 3.0% by weight.

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