SE545919C2

SE545919C2 - Method and system for processing lignocellulose biomass material

Info

Publication number: SE545919C2
Application number: SE2250279A
Authority: SE
Inventors: Francois Lambert; Peter Björklund
Original assignee: Valmet Oy
Priority date: 2022-03-01
Filing date: 2022-03-01
Publication date: 2024-03-12
Also published as: FR3133194A1; SE2250279A1; FI20235216A1; AT525944A2; NO20230142A1; CA3189197A1

Abstract

A method for processing lignocellulose biomass material comprising thermally treating (1) the lignocellulose biomass material at elevated pressure and temperature, recovering furfural (2) from vapors released from the lignocellulose material during said thermal treatment. The method further comprises mixing (3) at least part of a residue obtained from said recovering furfural with at least part of the thermally treated lignocellulose biomass material and/or with by-products comprising lignin obtained from biochemical treatment of the thermally treated lignocellulose biomass material. A corresponding system is also provided.

Description

METHOD AND SYSTEM FOR PROCESSING LIGNOCELLULOSE BIOMASS MATERIAL TECHNICAL FIELD The invention relates to the field of methods for processing lignocellulose biomass material comprising thermally treating the biomass material and recovering furfural from vapors released from the biomass material during the thermally treating. The invention also relates to a corresponding system.

BACKGROUND Thermal treatment of lignocellulose biomass material at elevated pressure and temperature is known in the art. Such thermal treatment is used for example to produce fibre board, fuel pellets or fuel briquettes. Pellets produced with thermal treatment are usually referred to as black pellets due to their dark color. One advantageous method for thermal treatment is steam explosion. Steam explosion refers to a process step where the material undergoes a rapid/instantaneous pressure decrease. Hot and softened biomass from thermal treatment is released or blown from a pressurized reactor through a blow valve or orifice, while the pressure drops to an environment with substantially lower pressure, such as below 5 bar, or preferably to substantially atmospheric pressure. The structure of the biomass breaks, partly due to the expanding steam, and partly by the shear forces and impact during the blow through the orifice or valve. Steam explosion treatment simplifies subsequent pelletizing or briquetting due to the (still) soft material being easy to densify. Steam explosion treatment improves the strength of the resulting pellet due to various substances such as lignin and sugars being released during the steam explosion.

A large amount waste steam, so-called "blow steam" is released from the mixture of steam and hot moist biomass which is discharged through the blow valve/orifice. The blow steam is separated from the biomass with a separator, for example a cyclone or a centrifuge. Blow steam in this context refers to a mixture of (water) steam and volatile organic compounds released from the biomass material during thermal treatment/ steam explosion discharge of the biomass material. More specifically, the blow steam comprises, beside steam (being the main component), gas-phase acidic compounds like formic and acetic acid, and non-acidic compounds like furfural and methanol derived from hemicelluloses during thermal treatment of the biomass. These compounds are considered as pollutants and cannot be released to the atmosphere. The compounds may however in some cases have a high market value. For example, furfural is used as such or refined to solvents, fuel, resin, fungicides, nematicides and other. Recovering valuable compounds from the blow-steam to saleable products can thus improve the overall revenues.

Methods for recovering furfural from blow steam are known in the art. WO2021167511 discloses a method for recovery of energy from a continuously operated steam explosion reactor for production of biomass pellets or briquettes, the method comprising the steps of: condensing a blow-steam from the steam explosion reactor for receiving a blow-steam condensate; recovering heat from the condensation of the blow-steam to energize a fractionation system, in which fractionation system furfural is recovered from the blow-steam condensate. One problem with this method, and other methods known in the art is that residues comprising polymers are obtained from the furfural recovery process. WO2021167511 is silent regarding the treatment or disposal of these residues.

SUMMARY An object of the invention is to provide a method and a corresponding system which solves the problem of disposing the residues from the furfural recovery process.

These and other objects are achieved by the present invention by means of a method and a system according to the independent claims.

According to a first aspect of the invention, there is provided a method for processing lignocellulose biomass material comprising thermally treating the lignocellulose biomass material at elevated pressure and temperature, recovering furfural from vapors released from the lignocellulose material during said thermal treatment. The method further comprises mixing at least part of a residue obtained from said recovering furfural with at least part ofthe thermally treated lignocellulose biomass material and/or with by-products comprising lignin obtained from biochemical treatment of the thermally treated lignocellulose biomass material. ln other words, the lignocellulose biomass material is subjected to thermal treatment at elevated pressure and temperature to obtain thermally treated lignocellulose biomass material and vapors released from the lignocellulose material during the thermal treatment. The vapors are thereafter, either directly or following one or more treatment steps such as condensation, subjected to a furfural recovery step to obtain furfural and one or more residues. At least part, or all, of the residues are mixed with, or put differently added to, either at least part, or all, of the thermally treated lignocellulose biomass material and/or mixed with/added to by-products comprising lignin obtained from biochemical treatment of the thermally treated lignocellulose biomass material. lt is understood that the biochemical treatment step is optional in the sense that it is not necessarily part of the method in the case that the residues are solely mixed with/added to the thermally treated lignocellulose biomass material.

The thermally treating may be conducted using at least one pressurized reactor, and the method may further comprise discharging the lignocellulose biomass material and blow steam comprising said vapors from the at least one pressurized reactor by means of steam explosion discharge. The method may further comprise separating the blow steam from the discharged thermally treated lignocellulose biomass material and condensing the blow steam to obtain a blow steam condensate, wherein said furfural is recovered from said vapors in condensed form as part of the blow steam condensate. The thermal treatment may comprise a continuous or a batch process.

The lignocellulose biomass material may for example be in the form wood chips, bark, saw-dust, straw, bagasse, or empty fruit bunches. The residues from the furfural recovery may comprise a mixture of organic carbohydrate derived polymers.

The invention is based on the insight that the disposal problem of the residues from the furfural recovery process can effectively be handled by mixing the residue with the thermally treated lignocellulose biomass material and/or with by-products comprising lignin obtained from biochemical treatment of the thermally treated lignocellulose biomass material. The invention is further based on the insight that the residue comprises a mixture of organic polymers, and that such organic polymers can improve the properties of said thermally treated biomass or said by-products when mixed therewith. This insight is particularly relevant when the thermally treated biomass or by-products is/are used to form pellets or briquettes, where the addition of organic polymers may result in pellets or briquettes having improved durability and/or moisture resistance. Furthermore, the residue has a heating value which is recovered when it is mixed into a fuel pellet or briquette. ln the invention, recovering furfural comprises stripping and rectification in combination with decanting in one or more steps. The residues are obtained as a bottom fraction from a final purification step of the furfural recovery. ln embodiments, the method further comprises the step of biochemical treatment which comprises enzymatic or acid hydrolysis and subsequent fermentation of the discharged thermally treated biomass material, wherein the by-products are obtained as by-products following the hydrolysis and/or the fermentation step. ln embodiments, the method further comprises, after the mixing, forming pellets and/or briquettes from at least part, or all, of the mixture obtained by said mixing. The method may, additionally or alternatively, further comprise, after the mixing, burning at least part, or all, of the mixture obtained by said mixing to provide heat to the thermally treating. The method may, additionally or alternatively, further comprise, after the mixing, collecting at least part, or all, of the mixture obtained by the mixing for use as fuel.

The mixing may comprise controlling the ratio between the residue and the discharged thermally treated biomass material and/or by-products comprising lignin to control physical properties such as mechanical durability and/or water resistance of the product (pellets or briquettes for instance). lt is understood that, depending on the raw material used, the physical properties of the finished product vary. By controlling the ratio between the residue and the discharged thermally treated biomass material and/or by-products comprising lignin, the addition of polymers is controlled, and consequently, the physical properties can be varied. ln particular, the ratio may be increased (i.e., more residue is added) to improve mechanical durability and/or water resistance. ln embodiments, the method further comprises, prior to thermally treating, or prior to mixing, drying the lignocellulose biomass material, i.e., reducing the moisture content of the biomass material. The moisture content may be reduced by mechanically dewatering the biomass material to obtain a moisture content in the range 35-55 %. Optionally, the dewatered biomass material may be thermally dried to obtain a moisture content in the range 6-25 %. The mechanical dewatering may comprise mechanically dewatering with a screw-press. Thermally drying may comprise drying the biomass with a low temperature belt dryer.

According to a second aspect of the invention, a system for processing biomass material is provided. The system comprises a thermal treatment system arranged to thermally treat the lignocellulose biomass material at elevated pressure and temperature, collecting means connected to the thermal treatment system to collect vapors released from the lignocellulose biomass material, and a furfural recovery system connected, directly or indirectly, to the collecting means, said furfural recovery system being arranged to process said vapors to obtain furfural and one or more residues. The system further comprises a mixing device connected to the thermal treatment system and to the furfural recovery system, the mixing device being arranged to mix at least part, or all, of the residues with at least part, or all, of the thermally treated lignocellulose biomass material. Alternatively, the system comprises a biochemical treatment system connected to the thermal treatment system to provide biochemically treated biomass material and by-products comprising lignin, and a mixing device connected to the biochemical treatment system and to the furfural recovery system, the mixing device being arranged to mix at least part, or all, of said residues with at least part, or all, of the by-products comprising lignin. ln the system, the furfural recovery system comprises at least one stripping and rectification device and at least one decanting device. The furfural recovery system further comprises a final purification stage from which the residue is obtained as a bottom fraction. ln embodiments of the system, the biochemical treatment system comprises at least one enzymatic or acid hydrolysis stage and at least one subsequent fermentation stage, wherein the by-products are obtained as by-products from the hydrolysis and/or the fermentation step. ln embodiments of the system, at least one pelleting/briquetting device is connected to the mixing device and arranged to produce fuel pellets/briquettes based on the mixture obtained from said mixing device. Pelleting/briquetting devices are known in the art and will not be explained in further detail here. ln embodiments of the system, the thermal treatment system comprises: - at least one pressurized reactor arranged to receive the lignocellulose biomass material, the at least one reactor being provided with means for adding steam (such as steam injection nozzles) into said at least one reactor for thermal treatment of the biomass material at elevated pressure and temperature, and - at least one steam explosion discharge device arranged to discharge the biomass material and blow steam from the at least one reactor, the blow steam comprising steam and the vapors released from the biomass material.

Further, the collecting means may comprise separating means connected to the at least one steam explosion discharge device to separate the blow steam from the discharged thermally treated biomass material. The separating means may comprise a cyclone. ln embodiments, the system further comprises at least one condensing device connected to the separating means to provide a blow steam condensate, wherein the furfural recovery system is connected to the at least one condensing device to recover furfural from the vapors in condensed form as part of blow steam condensate. ln embodiments, blow steam is conducted from the separating means to the furfural recovery system without previous condensation. ln embodiments, the system further comprises a drying arrangement comprising at least one mechanical dewatering apparatus and/or at least one therma| drying apparatus. The drying arrangement may be arranged to reduce the moisture content of the biomass, i.e. dry the biomass, upstream of the therma| treatment system or, may alternatively be arranged downstream of the therma| treatment system and upstream of the mixing device. ln embodiments comprising a biochemica| treatment system, a drying arrangement comprising at least one mechanical dewatering apparatus and/or at least one therma| drying apparatus may be arranged to dry or reduce the moisture content of the by-products prior to being fed to the mixer. The at least one mechanical dewatering apparatus, which may comprise a screw-press, may be configured to dewater the biomass material or by-products to obtain a moisture content in the range 35-55 %. The therma| drying apparatus, which may comprise a low temperature belt dryer, may be configured to thermally dry the biomass material or by-products to obtain a moisture content in the range 6-25 %. ln embodiments, the system further comprises additional means for collecting vapors from reliefs on the at least one reactor, the additional means for collecting vapors being connected to the furfural recovery system, either directly or via a condensing device, to provide collected vapors thereto. Consequently, furfural is recovered from the blow steam as well as from the vapor obtained from reliefs on the at least one reactor.

The features of the embodiments described above are combinable in any practically realizable way to form embodiments having combinations of these features. Further, all features and advantages of embodiments described above with reference to the first aspect of the invention may be applied in corresponding embodiments of the system according to the second aspect of the invention and vice VefSa.

BRIEF DESCRIPTION OF THE DRAWINGS Above discussed and other aspects of the present invention will now be described in more detail using the appended drawings, which show presently preferred embodiments of the invention, wherein: fig. 1 shows a flow chart illustrating an embodiment of the method according to the first aspect of the invention; fig. 2 shows a flow chart illustrating another embodiment of the method according to the first aspect of the invention; fig. 3 shows a schematic illustration of an embodiment of the system according to the second aspect of the invention; and fig. 4 shows a schematic illustration of another embodiment of the system according to the second aspect of the invention.

DETAILED DESCRIPTION Fig. 1 shows a flow chart illustrating an embodiment of the method according to the first aspect of the invention. The method comprises thermally treating 1 the lignocellulose biomass material at elevated pressure and temperature, for instance in a pressurized reactor vessel as will be explained below with reference to fig. 3-4. Optionally, the method comprises reducing the moisture content of the biomass prior to thermally treating by means of mechanically dewatering the biomass 8a (for example using a screw press) and/or thermal drying 8b of the biomass (for example using a low-temperature belt dryer). The thermally treated biomass along with blow steam is discharged by means of steam explosion discharge 9. The blow steam is thereafter separated 9 from the discharged thermally treated lignocellulose biomass material, for example using a cyclone. The blow steam is condensed 10 to form a blow steam condensate, which condensate is thereafter subjected to a furfural recovery process 2 to obtain furfural and a residue comprising a mixture of organic polymers. Embodiments of the furfural recovery process is described below with reference to fig. 3-4. Optionally, the moisture content of the thermally treated lignocellulose biomass material is reduced by means of mechanically dewatering 8a' (for example using a screw press) and/or thermal drying 8b' (for example using a low-temperature belt dryer). At least part of the residue comprising a mixture of polymers at least part of the thermally treated lignocellulose biomass material is mixed 3. The mixture obtained from step 3 may be used for different purposes. For example, pellets/briquettes may be formed 5 from at least part of the mixture. Alternatively, or additionally, at least part of the mixture may be combusted/burned 6 to provide heat/steam to the thermally treating step 1 and/or to other steps in the method. Alternatively, or additionally, at least part of the mixture may be collected 7 for use as fuel, either in the thermal treatment plant or at another location.

Fig. 2 shows a flow chart illustrating another embodiment of the method according to the first aspect of the invention. This embodiment corresponds to the embodiment in fig. 1 in that it comprises corresponding steps 1, 1a, 2, 9, 10 and optional steps 5, 6, 7, 8a. The embodiment however differs in that: - optionally, an acid catalyst, for example sulfuric acid, is added 11 to the biomass prior to mechanically dewatering 8a. - the thermally treated biomass from step 9 is subjected to an acid or enzymatic hydrolysis step 4a to produces fermentable sugars, followed by a fermentation step 4b to produce ethanol. A by-product comprising lignin is obtained from the hydrolysis step 4a and/or the fermentation step 4b. - the mixing step 3 comprises mixing at least part of the residue comprising a mixture of polymers from step 2 with the by-product from step 4a and/or 4b. - optionally, at least part, or all, of the by-product may be mechanically dewatered, 12a, and/or thermally dried, 12b, prior to mixing it with polymeric residue, Fig. 3 shows a schematic illustration of an embodiment of the system according to the second aspect of the invention. The system comprises a mechanical dewatering apparatus being a screw-press 107a which is configured to dewater the lignocellulose biomass material to obtain a moisture content in the range 35-55 %. Following the screw-press, a low temperature belt dryer is arranged which is configured to thermally dry the biomass material to obtain a moisture content in the range 6-25 %. The dewatered and dried lignocellulose biomass material is collected in a bin or vessel and is fed therefrom to a thermal treatment system 101 using a plug-screw 107c. The thermal treatment system comprises a pressurized reactor 101a. The plug-screw compresses the biomass to a plug such that the high pressure in the thermal reactor 101a is sealed from the atmospheric pressure. The thermal reactor 101a is provided with means 101b for adding steam into said at least one reactor for thermal treatment of the lignocellulose biomass material at elevated pressure and temperature, and at least one steam explosion discharge device 101c arranged to discharge the thermally treated biomass and blow steam (comprising steam and vapors released from the biomass material during thermal treatment). Collecting means in the form of a separator (a cyclone) 102 is connected to the steam explosion discharge device 101c to separate blow steam from the lignocellulose biomass material. A condensing device 108 is connected to the separator 102 to condense the blow steam.

A furfural recovery system 103 is connected to the condensing device 108 to receive the blow steam condensate. The furfural recovery system is schematically illustrated in the form of a simplified embodiment which comprises a distillation column 103a, a dehydration column 103b, a gravimetric decanter 103c, reflux condensing devices 109a, 109c and a product condensing device 109b. The blow steam condensate is fed to the distillation column 103a in which furfural is rectified and withdrawn as an overhead vapor to the reflux condensing device 109a. The reflux condensate from the reflux condensing device 109a is fed to a gravimetric decanter 103c, which gravimetric decanter is connected to the dehydration column 103b to provide a furfural phase (heavy phase) thereto. The water phase which contains some furfural is returned as reflux to an upper portion of the distillation column 103a.

The lower part of the distillation column 103a comprises a stripping section. The stripping section is heated with low-pressure steam. Furfural is withdrawn from a lower part of the dehydration column 103b to a product condensing device 109b. The column 103b has a short stripping section in the bottom. Residues are obtained as a bottom fraction from the column 103b, which residues comprise various furfural derived condensation products including a mixture of organic polymers. The column 103b may also be referred to as a final purification stage. The reflux from column 103b is also provided to the decanter 103c via the reflux condensing device 109c. ln other embodiments, the furfural recovery system 103 may comprise further devices. For example, the furfural recovery system may be provided with reboilers to provide low-pressure steam to the columns, and further with heat recovery from the reflux condensing devices, as described in WO2021167511, which is hereby incorporated by reference.

The system further comprises a mixing device 104a connected to the separator 102 and to the column 103b to receive thermally treated biomass and the residues comprising polymers. The mixing device is arranged to mix the residues with the thermally treated lignocellulose biomass material. The mixture from mixing device 104a is fed to a pelleting/briquetting device 106 to produce pellets/briquettes from the mixture.

Fig. 4 shows a schematic illustration of another embodiment of the system according to the second aspect of the invention. This embodiment corresponds to the embodiment in fig. 3 in that it comprises corresponding devices/systems 101a-c, 103, 107c, 108. The embodiment however differs in that: - an acid hydrolysis catalyst, for example sulfuric acid, may be mixed to the lignocellulose biomass, for example by means of injection means 107d upstream of the screw 107c, - the biomass may be dewatered with the screw 107c, - the thermally treated biomass is fed to an enzymatic or acid hydrolysis reactor 105a and a subsequent fermentation stage 105b, wherein by-products comprising lignin are obtained as a bottom fraction from the fermentation stage, - the mixing device is connected to the fermentation stage and to the column 103b to receive the by-products comprising lignin and the residues comprising polymers. The mixing device is arranged to mix the residues with the by-products from the fermentation stage to produce a mixture which can be used as fuel. The fuel can be collected for use later or can be burned/combusted for instance to provide heat/steam to the pressurized reactor, and - optionally, part of, or all of, the lignin enriched bottom fraction from 105b, may be mechanically dewatered, for example with a screw press, 107e, and/or with a thermal dryer 107f prior to mixing with organic polymers in mixer 104b. ln other embodiments, the by-products comprising lignin can, additionally or alternatively, be obtained from the hydrolysis stage 105a.

Typical operating conditions of the embodiments described above with reference to figures 1-4 are as follows: - Temperature in reactor: 140-225 °C - Pressure: corresponding pressure 2 - 30 bar(g) - Residence time: 1 min - 3 hours, preferably 3-20 minutes.

Although not explicitly shown or described above, it is understood that the systems in figures 3-4 comprises feeding devices such as feeding screws, pumps, or valves where appropriate to convey and control the flows of biomass material, steam etc. between the shown devices. lt is further noted that the devices forming part of the described embodiments of the system, and used in the embodiments of the method, (such as screw-presses, dryers, pressurized reactors, condensing devices, distillation columns, dehydrating columns, decanters, pelleting devices, cyclones, steam explosion discharge devices, hydrolyzation reactors, fermentation vessels, mixers etc.) are all well known in the art and will therefore not be described in further detail herein.

The description above and the appended drawings are to be considered as non-limiting examples of the invention. The person skilled in the art realizes that several changes and modifications may be made within the scope of the invention. For example, the thermal treatment system can comprise a different type of reactor, the drying arrangement can be preceded by one or more washing stages, the furfural recovery system can comprise further stages and the residues comprising polymers do not necessarily need to be obtained from the final purification stage of the furfural recovery system.

Claims

Claims Method for processing lignocellulose biomass material, comprising: - thermally treating (1) the lignocellulose biomass material at elevated pressure and temperature; - recovering furfural (2) from vapors released from the lignocellulose material during said thermal treatment (1); - mixing (3) at least part of a residue obtained from said recovering furfural (2) with at least part of the thermally treated lignocellulose biomass material and/or with by-products comprising lignin obtained from biochemical treatment (4a, 4b) of the thermally treated lignocellulose biomass material, characterized in that said recovering furfural (2) comprises stripping and rectification in combination with decanting in one or more steps, and wherein the residue is obtained as a bottom fraction from a final purification step of said recovering furfural (2). Method according to claim 1, characterized in that the residue comprises a mixture of organic carbohydrate derived polymers. Method according to any of the preceding claims, characterized by further comprising said biochemical treatment which comprises enzymatic or acid hydrolysis (4a) and subsequent fermentation (4b) of the discharged thermally treated biomass material, wherein said by- products are obtained as by-products following the hydrolysis and/or the fermentation step. Method according to any of the preceding claims, characterized by further comprising, after said mixing (3), forming pellets and/or briquettes (5) from at least part of the mixture obtained by said mixing. Method according to any of the preceding claims, characterized by further comprising, after said mixing (3), burning (6) at least part of the mixture obtained by said mixing to provide heat to said thermally treating. Method according to any of the preceding claims, characterized by further comprising, after said mixing (3), collecting (7) at least part of the mixture obtained by said mixing for use as fuel. Method according to any of the preceding claims, characterized in that said mixing (3) comprises controlling the ratio between the residue and the discharged thermally treated biomass material and/or by-products comprising lignin to control physical properties such as mechanical durability and/or water resistance. Method according to any of the preceding claims, characterized by further comprising, prior to said thermally treating (1), or prior to said mixing (3), reducing the moisture content (8a, 8b, 8a', 8b') of the |ignoce||u|ose biomass material. Method according to any of the preceding claims, characterized by further comprising, prior to said mixing (3), reducing the moisture content (12a, 12b) of the by-products. Method according to any of the preceding claims, characterized in that said thermally treating (1) is conducted in at least one pressurized reactor, said method further comprising: - discharging (1a) the |ignoce||u|ose biomass material and blow steam comprising said vapors from the at least one pressurized reactor by means of steam explosion discharge. Method according to claim 10, characterized by further comprising: - separating (9) the blow steam from the discharged thermally treated |ignoce||u|ose biomass material, and - condensing (10) the blow steam to obtain a blow steam condensate, wherein said furfural is recovered from said blow steam condensate. System for processing |ignoce||u|ose biomass material, comprising: - A thermal treatment system (101) arranged to thermally treat the |ignoce||u|ose biomass material at elevated pressure and temperature; - Collecting means (102) connected to the thermal treatment system to collect vapors released from the |ignoce||u|ose biomass material; - A furfural recovery system (103) connected, directly or indirectly, to the collecting means (102), said furfural separation system being arranged to process said vapors to obtain furfural and one or more residues; wherein the system for processing |ignoce||u|ose biomass material further comprises - a mixing device (104a; 104b) connected to the thermal treatment system (101) and to the furfural recovery system (103), said mixing device being arranged to mix at least part of said residues with at least part of the thermally treated |ignoce||u|ose biomass material, or - a biochemical treatment system (105a, 105b) connected to the thermal treatment system to obtain biochemically treated biomass material and by-products comprising lignin, and a mixing device (104b) connected to the biochemical treatment system and to the furfural recovery system, said mixing device being arranged to mix at least part of said residues with at least part of the by-products comprising lignin, characterized in that said furfural recovery system (103) comprises at least one stripping and rectification device (103a), at least one decanting device (103c) and a final purification stage (103b), wherein said residue is obtained as a bottom fraction from said final purification stage. System according to claim 12, characterized by further comprising a drying arrangement (107e, 107f) arranged to mechanically dewater and/or thermally dry said by-products from the biochemical treatment system (105a, 105b) prior to mixing with said residues in said mixing device (104b). System according to any of c|aims 12-13, characterized in that said biochemical treatment system comprises at least one enzymatic or acid hydrolysis stage (105a) and a subsequent fermentation stage (105b), wherein said by-products are obtained as by-products following the hydrolysis and/or the fermentation step. System according to any of c|aims 12-14, characterized by further comprising at least one pe||eting device (106) connected to said mixing device (103a; 103b) and arranged to produce fuel pellets based on the mixture obtained from said mixing device. System according to any of c|aims 12-15, characterized in that said thermal treatment system (101) comprises: - at least one pressurized reactor (101a) arranged to receive the lignocellulose biomass material, said at least one reactor being provided with means (101b) for adding steam into said at least one reactor for thermal treatment of the biomass material at elevated pressure and temperature, and - at least one steam explosion discharge device (101c) arranged to discharge the biomass material and blow steam from the at least one pressurized reactor, said blow steam comprising steam and said vapors released from the biomass material, wherein said collecting means (102) comprises separating means connected to the at least one steam explosion discharge device (101c) to separate said blow steam from the discharged thermally treated biomass material.