Recovery system and recovery method of organic solvent-soluble lignin

Abstract

To provide a recovery system and a recovery method of organic solvent-soluble lignin from which solid state lignin is stably obtained.SOLUTION: A recovery system of organic solvent-soluble lignin is provided with a thin film type dryer constituted such that an extraction liquid extracted with a mixed solvent of an organic solvent and water from a solid matter containing lignin is dried and forms a thin film-like dried matter containing solid organic solvent-soluble lignin. A recovery method of the organic solvent-soluble lignin includes a drying process in which an extracted liquid containing the organic solvent-soluble lignin extracted with a mixed solvent of an organic solvent and water from a solid matter containing the lignin is dried, and a thin film-like dried matter containing solid state organic solvent-soluble lignin is formed.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a system and method for recovering organic solvent-soluble lignin. [Background technology]

[0002] In recent years, the use of biomass made from plant resources has been attracting attention from the viewpoint of global warming countermeasures and effective utilization of waste. In general, carbohydrates such as sugarcane and starches such as corn are often used as raw materials for producing compounds such as ethanol from biomass. However, these raw materials were originally used as food or feed, and their long-term use as industrial resources may cause competition with food or feed use, leading to a risk of a rise in raw material prices.

[0003] Therefore, technological development is being promoted to utilize non-edible biomass as an energy resource. Cellulose is the most abundant non-edible biomass on earth, and most of it exists as lignocellulose, which is a complex with aromatic polymers lignin and hemicellulose.

[0004] Ethanol production using lignocellulosic biomass as a raw material involves a pretreatment step in which the biomass raw material is thermochemically pretreated, a saccharification step in which the biomass after the pretreatment step is enzymatically treated to produce a saccharified liquid, a fermentation step in which a microbial culture solution is added to the saccharified liquid obtained in the saccharification step to perform ethanol fermentation, and a purification step in which ethanol is separated from the fermented liquid obtained in the fermentation step by distillation or the like. In this ethanol production, there is a problem that a large amount of fermentation residue is generated because lignin remains as a solid. This fermentation residue is generally treated by boilers or methane fermentation in an attached factory, and is not currently being effectively utilized.

[0005] Similarly, in the papermaking process using non-edible biomass as a raw material, lignin-based products (black liquor, lignin sulfonate) are generated as residues, and technologies to utilize them effectively have been developed over many years. However, since the lignin is sulfonated or chlorinated in the process of chemically decomposing the biomass, it is difficult to utilize, and most of it is only used as fuel for boiler heat source.

[0006] On the other hand, since phenol derivatives and the like can be obtained by decomposing lignin, they can be used as raw materials for chemical industrial products such as resin raw materials, composite materials, surfactants, etc. Therefore, there is a demand for the development of a method for efficiently producing decomposition products of lignin.

[0007] Patent Document 1 discloses a method for producing a lignin decomposition product by treating a lignin-containing biomass with a mixed solvent having a molar ratio of water to alcohol of 1 / 1 to 20 / 1. Patent Document 2 discloses a method for producing low-molecular-weight lignin by heating a lignin-containing biomass in a mixed solvent of hydrocarbon and alcohol in the presence of an acid catalyst. Patent Document 3 discloses a method for producing a lignin decomposition product by pretreating a lignin-containing biomass by combining hydrothermal treatment and pulverization, enzymatically saccharifying the pretreated biomass, subjecting the enzymatic saccharification residue generated during the enzymatic saccharification, further subjecting the enzymatic saccharification residue generated during the enzymatic saccharification, and dissolving the solid in an organic solvent to produce a lignin decomposition product. Patent Document 4 discloses a method for producing a lignin decomposition product by enzymatically saccharifying a lignin-containing biomass to obtain a saccharification residue, heat-treating the saccharification residue in a mixed solvent containing water and an organic solvent having a solubility in water of 90 g / L or more at 20°C to obtain a heat-treated liquid containing a lignin decomposition product, and then performing solid-liquid separation of the heat-treated liquid to remove insoluble matter to produce a lignin decomposition product. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2014-015439 A [Patent Document 2] JP 2016-050200 A [Patent Document 3] JP 2015-157792 A [Patent Document 4] JP 2013-241391 A Summary of the Invention [Problem to be solved by the invention]

[0009] The lignin obtained by the methods described in Patent Documents 1 to 4 is in the form of a solution dissolved or dispersed in a solvent. Conventionally, attempts have been made to add the solution to a stirring tank or the like equipped with a heating jacket, and volatilize the solvent over time by heating and concentrating to recover solid lignin from the solution. However, due to the influence of moisture and organic solvents remaining during heating and concentration, the lignin precipitates as a tar-like deposit, making it difficult to stably obtain solid lignin.

[0010] The present invention has been made in consideration of the above circumstances, and provides a system and method for recovering organic solvent-soluble lignin, which can stably obtain solid lignin. [Means for solving the problem]

[0011] That is, the present invention includes the following aspects. (1) A system for recovering organic solvent soluble lignin, comprising: A recovery system including a thin-film dryer configured to dry an extract containing organic solvent-soluble lignin extracted from a solid material containing lignin with a mixed solvent of an organic solvent and water, and form a thin-film dried material containing solid organic solvent-soluble lignin. (2) The recovery system described in (1), wherein the thin film dryer has a scraping mechanism configured to scrape off the dried material. (3) The recovery system according to (1) or (2), further comprising an extraction device configured to separate the extract from the solid matter by the mixed solvent, upstream of the thin film dryer. (4) The recovery system according to (3), further comprising an evaporator tank upstream of the thin film dryer and downstream of the extraction device. (5) The recovery system according to (4), further comprising a separation device downstream of the thin film dryer, the separation device being configured to separate water and an organic solvent from the volatile components discharged from the thin film dryer and the volatilization tank. (6) The recovery system according to (5), wherein the separation device is a distillation device. (7) A pipe configured to send the distillate obtained in the distillation apparatus to the extraction apparatus, The recovery system according to (6), wherein the distillation apparatus has a control unit that controls a reboiler boil-up amount and a reflux amount so that a content ratio of water and an organic solvent in the distillate is within a predetermined range.

[0012] (8) A method for recovering organic solvent-soluble lignin, comprising the steps of: A recovery method comprising a drying step of drying an extract containing organic solvent-soluble lignin extracted from a solid material containing lignin with a mixed solvent of an organic solvent and water to form a thin-film-like dried product containing solid organic solvent-soluble lignin. (9) The method according to (8), further comprising a collection step of collecting the dried product after the drying step. (10) The method according to (8) or (9), further comprising an extraction step of mixing the solid with the mixed solvent and separating the extract prior to the drying step. (11) The method according to (10), further comprising a volatilization step of volatilizing a portion of the mixed solvent contained in the extract before the drying step and after the extraction step. (12) The method according to (11), wherein in the volatilization step, a part of the mixed solvent is volatilized until the content of the organic solvent in the extract is 50 mass% or more and less than 60 mass%, based on the total mass of water and the organic solvent in the extract. (13) The method according to (11) or (12), further comprising, after the drying step, a separation step of separating water and an organic solvent from the volatile components discharged in the drying step and the volatilization step. (14) The method according to (13), wherein the separation step is a distillation step carried out by a distillation method. (15) The method further comprises, after the distillation step, a recycling step of recycling the distillate obtained in the distillation step to the extraction step, The method for recovering the organic solvent according to (14), wherein in the distillation step, a reboiler boiling rate and a reflux rate are controlled so that a content ratio of water to organic solvent in the distillate falls within a predetermined range. (16) The method according to (15), wherein in the recycling step, the supply amounts of the distillate and the water are controlled so as to achieve a content ratio of water and the organic solvent in the mixed solvent used in the extraction step. Effect of the Invention

[0013] According to the above-described aspects of the system and method for recovering organic solvent-soluble lignin, it is possible to provide a system and method for recovering organic solvent-soluble lignin that can stably obtain solid lignin. [Brief description of the drawings]

[0014] [Figure 1A] FIG. 1 is a schematic diagram showing changes in a solution containing water, an organic solvent, and organic solvent-soluble lignin when the solution is dried by a conventional heating and concentration method. [Figure 1B] FIG. 2 is a schematic diagram showing changes in a solution containing water, an organic solvent, and organic solvent-soluble lignin when the solution is dried using a thin-film dryer. [Diagram 2] FIG. 1 is a schematic configuration diagram showing a recovery system for organic solvent-soluble lignin according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic diagram showing a recovery system for organic solvent-soluble lignin according to a second embodiment of the present invention. [Figure 4] FIG. 1 is a schematic configuration diagram showing a recovery system for organic solvent-soluble lignin according to a third embodiment of the present invention. [Diagram 5] FIG. 1 is a schematic configuration diagram showing a recovery system for organic solvent-soluble lignin according to a fourth embodiment of the present invention. [Figure 6A]FIG. 2 is a vertical cross-sectional view of the disk dryer in the first embodiment. [Figure 6B] FIG. 2 is a side view of the disk dryer in the first embodiment. [Figure 7] 1 is a graph showing the change over time in the volatilization rate of an organic solvent (acetone or ethanol) in the extract in Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a recovery system for organic solvent-soluble lignin according to an embodiment of the present invention (hereinafter, may be abbreviated as "recovery system of the present embodiment") and a recovery method for organic solvent-soluble lignin (hereinafter, may be abbreviated as "recovery method of the present embodiment") will be described in detail. In this specification and claims, the meanings of various terms are defined as follows.

[0016] <Lignocellulosic biomass> An example of the lignin-containing solid material used as a raw material in the recovery system and recovery method of this embodiment is lignocellulosic biomass. The lignocellulosic biomass may be at least one selected from the group consisting of woody plants (also called woody biomass), herbaceous plants (also called herbaceous biomass), their processed products, and their waste products. The lignocellulosic biomass may be crushed and may be in any form, such as blocks, chips, or powder. The lignin-containing solid material may be a residue generated in the process of producing bioethanol, biobutanol, or biochemical products from cellulose and hemicellulose in lignocellulosic biomass. In the case of the residue, it is preferable that the residue is a saccharification residue remaining after pretreating lignocellulosic biomass by dilute sulfuric acid cooking and further decomposing the obtained pretreated raw material by enzymatic saccharification.

[0017] Examples of the woody plants include cedar, cypress, larch, pine, American pine, American cedar, American hemlock, poplar, white birch, willow, eucalyptus, sawtooth oak, konara oak, oak, chinquapin, beech, acacia, bamboo, bamboo grass, oil palm, sago palm, etc. Among them, cedar is preferable as the woody plant from the viewpoint of stability of properties.

[0018] In addition, bark, branches, fruit bunches, fruit shells, etc. of the above woody plants can also be used. In addition, processed materials such as plywood, fiberboard, and laminated lumber made from the above woody plants can also be used. In addition, members dismantled after use in buildings can also be used. In addition, processed products of lignocellulosic biomass such as paper and waste paper can also be used.

[0019] Examples of the herbaceous plants include bamboo, palm, rice (including rice straw), wheat (including wheat straw), sugarcane (including bagasse), reed, Japanese silver grass, corn (including corn stover, corn cob, and corn hull), sorghum (including sweet sorghum), switchgrass, erianthus, napier grass, and other grasses; jatropha, cashew, and the like.

[0020] Among them, the lignin-containing solid material used as the raw material in the recovery system and recovery method of the present embodiment is preferably a herbaceous plant (herbaceous biomass), and more preferably a Gramineae plant.

[0021] <Lignin> In general, lignin is a natural polymer that is one of the three main components of herbaceous biomass. Among herbaceous biomass, bagasse contains 5% to 30% by mass of lignin.

[0022] Lignin has a basic skeleton composed of an aromatic nucleus (benzene nucleus), and is classified into G nucleus, S nucleus, and H nucleus based on its structure. A G nucleus has one methoxy group (-OCH3) at the ortho position of the phenol skeleton, an S nucleus has two methoxy groups at the ortho position, and an H nucleus has no methoxy group at the ortho position. Lignin in herbaceous biomass such as bagasse contains all of the H nucleus, G nucleus, and S nucleus as basic skeletons. Among lignins derived from woody biomass, lignin derived from coniferous trees has a G nucleus as the basic skeleton, and lignin derived from broadleaf trees has a G nucleus and an S nucleus as the basic skeleton.

[0023] As used herein, the term "organic solvent-soluble lignin" refers to lignin that is soluble in an organic solvent, and more specifically, refers to lignin contained in an extract obtained by extracting a lignin-containing solid (such as lignocellulosic biomass) with a mixed solvent of an organic solvent and water in the extraction process described below.

[0024] <Cellulose and hemicellulose> In this specification, "cellulose" includes hexose, which is a unit of six carbons. Thus, when cellulose is hydrolyzed, it produces a hexose monosaccharide (such as glucose) consisting of six carbons, and a hexose oligosaccharide (such as cellobiose) in which multiple such monosaccharides are linked together.

[0025] "Hemicellulose" includes complex polysaccharides such as glucomannan and glucuronoxylan, which are composed of pentoses (C5 sugars) with five carbon units such as xylose, and hexoses (C6 sugars) with six carbon units such as mannose, arabinose, and 4-O-methylglucuronic acid. Thus, when hemicellulose is hydrolyzed, it produces pentose monosaccharides with five carbons, pentose oligosaccharides in which multiple pentose monosaccharides are linked together, hexose monosaccharides with six carbons, hexose oligosaccharides in which multiple hexose monosaccharides are linked together, and oligosaccharides in which multiple pentose and hexose monosaccharides are linked together.

[0026] In general, the composition ratio and amount of monosaccharides or oligosaccharides produced from hemicellulose or cellulose vary depending on the pretreatment method and the type of lignocellulosic biomass used as a raw material.

[0027] <Recovery system for organic solvent-soluble lignin> The recovery system of this embodiment includes a thin-film dryer configured to dry an extract containing organic solvent-soluble lignin extracted from a solid material containing lignin with a mixed solvent of an organic solvent and water, and form a thin-film dried material.

[0028] Conventionally, the extraction liquid is added to a stirring tank equipped with a heating jacket, and the solvent is evaporated over time by heating and concentration, so that solid lignin is recovered from the solution. FIG. 1A shows a schematic diagram of the change in the solution when a solution containing water, an organic solvent, and organic solvent-soluble lignin is dried by a conventional heating and concentration method. In the solution before heating, water 1, organic solvent 2, and organic solvent-soluble lignin 3 are uniformly dispersed. In the drying by the conventional heating and concentration method, the organic solvent 2 is evaporated and removed first while the mixed solvent is gradually evaporated and removed over time. As a result, the balance of water 1, organic solvent 2, and organic solvent-soluble lignin 3 in the solution is lost, and the organic solvent-soluble lignin 3 attracts each other and starts to aggregate. Furthermore, since the organic solvent-soluble lignin is amphiphilic, it aggregates and precipitates while taking in water 1. Furthermore, since the drying proceeds slowly over a long period of time, the aggregation and precipitation proceeds, and finally a tar-like dried product containing moisture is formed. For this reason, it is difficult to stably obtain solid organic solvent-soluble lignin.

[0029] 1B is a schematic diagram showing the change in a solution containing water, an organic solvent, and organic solvent-soluble lignin when the solution is dried using a thin-film dryer. In the drying using a thin-film dryer, water 1 and organic solvent 2 are evaporated from the solution before the above-mentioned lignin aggregates and precipitates, and the solution is dried, and a thin-film-like dried material containing organic solvent-soluble lignin 3 is efficiently formed. Therefore, by including the thin-film dryer having the above-described configuration, the recovery system of the present embodiment can stably recover solid, organic solvent-soluble lignin that does not contain water and does not recondense.

[0030] 2 is a schematic diagram showing a recovery system for organic solvent-soluble lignin according to the first embodiment of the present invention. The recovery system of this embodiment will be described in detail below with reference to FIG.

[0031] The recovery system 100 shown in FIG.

[0032] [Thin film dryer] The thin-film dryer 10 is configured to volatilize the volatile components 6 (mainly the mixed solvent) from the extract 4 to form a thin-film dried product consisting of solids (mainly solid organic solvent-soluble lignin 3a) contained in the extract 4. The thin-film dryer 10 may, for example, have a member including a heat transfer surface. The member including the heat transfer surface is configured so that the heat transfer surface is heated by steam or the like. Furthermore, the member including the heat transfer surface can form a thin-film dried product by applying a thin layer of the extract to the heat transfer surface and volatilizing the volatile components from the extract before the above-mentioned aggregation and precipitation of lignin occurs. The thin-film dried product refers to a dried product having a thickness of 300 μm or less. The shape of the heat transfer surface is not particularly limited, and may be flat or three-dimensional. In the case of a planar shape, examples include an approximately circular shape (including a perfect circle), a hollow approximately circular shape (including a hollow perfect circle), a sector shape, a ring sector shape, a polygonal shape, etc., with approximately circular shapes (including a perfect circle), a hollow approximately circular shape (including a hollow perfect circle), a sector shape, or a ring sector shape being preferred. In the case of a three-dimensional shape, examples include a cylindrical shape, a prismatic shape, a pyramidal shape, a truncated pyramidal shape, a conical shape, a truncated conical shape, etc., with a cylindrical shape being preferred. The material of the heat transfer surface may be any material that easily conducts heat, but it is preferable that the material be highly abrasion resistant and capable of withstanding the scraping operation by the scraping mechanism described below. For example, steel material that has been treated with hard chrome plating or electroless nickel plating may be mentioned.

[0033] The thin film dryer 10 preferably has a scraping mechanism. The scraping mechanism is configured to scrape off the dried material. By having the scraping mechanism, the thin film dryer can scrape off and collect the thin film-like dried material formed on a heat transfer surface such as a disk surface or a drum surface. In addition, the thin film-like dried material is crushed by the scraping operation, and powdery organic solvent-soluble lignin can be collected. Specific examples of the scraping mechanism include a scraper. The scraper may be blade-shaped (also called knife-shaped or blade-shaped) or spatula-shaped. The scraping mechanism refers to a mechanism that scrapes the surface on which the dried material is located to peel off the dried material from the surface.

[0034] Moreover, the thin film dryer preferably further has a rotating shaft member in addition to the scraping mechanism. The rotating shaft member is configured to heat the member including the heat transfer surface by a method such as supplying steam into the shaft, and to rotate the member including the heat transfer surface around the center of the heat transfer surface as an axis. By having the scraping mechanism and the rotating shaft member, the thin film dryer can efficiently dry the extract and recover the dried product during one rotation of the member including the heat transfer surface, and can continuously recover organic solvent-soluble lignin.

[0035] The thin-film dryer may be equipped with a feed pipe configured to add the extract onto the heat transfer surface, a circulation mechanism (e.g., a mechanism consisting of a circulation tank and piping) configured to collect the extract not adhering to the heat transfer surface, circulate it, and supply it to the feed pipe, and other known configurations. Examples of the shape of the feed pipe include an opening type such as a faucet or a hose outlet, a shower type, and a spray type. Instead of the feed pipe, the thin-film dryer may be configured to directly immerse a part of the heat transfer surface in a storage tank (or a liquid reservoir) containing the extract while rotating it.

[0036] Specific examples of thin-film dryers include conductive heat transfer dryers such as disk dryers (see Figs. 6A and 6B) and drum dryers (drum dryers). Disk dryers are configured to spray an extract onto a disk surface (one or both sides) heated by steam, volatilize volatile components during one rotation of the disk, and dry the material. Drum dryers are configured to attach an extract onto a drum surface (external wall surface of the drum) heated by steam, and volatilize liquid components during one rotation of the drum, and dry the material. Disk dryers and drum dryers are usually equipped with a scraper for recovering a thin-film dried material. Disk dryers and drum dryers are classified into normal pressure type and vacuum type depending on the operating pressure, but any type can be used. Drum dryers are classified into double drum type, twin drum type, and single drum type depending on the number of drums, but any type can be used. The single drum type includes a dip type, a spray type, a splash type, an upper roll type (single stage, multistage), a side roll type, a lower roll type, etc., depending on the liquid supply method, and any type can be used. Among them, as a thin film type dryer, a disk dryer is preferable because it is space-saving and can efficiently recover solid organic solvent-soluble lignin.

[0037] In the thin film dryer 10, the surface area of ​​the heat transfer surface, the rotation speed of the rotating shaft member, and the flow rate per hour at which the extract liquid is added to the heat transfer surface are items that can be appropriately designed by a person skilled in the art depending on the composition of the extract liquid to be dried, the amount of the extract liquid, etc.

[0038] The solid organic solvent-soluble lignin 3a dried in the thin film dryer 10 can be recovered via a pipe 11, while the volatile components 6 are discharged to the outside of the apparatus via a pipe 12.

[0039] Fig. 3 is a schematic diagram showing a recovery system for organic solvent-soluble lignin according to a second embodiment of the present invention. The recovery system 200 shown in Fig. 3 differs from the recovery system 100 shown in Fig. 2 in that it further includes an extractor 20 and a solid-liquid separator 30 upstream of the thin-film dryer 10. In Fig. 3 and subsequent figures, the same components as those shown in Fig. 2 are designated by the same reference numerals and will not be described.

[0040] [Extraction device] The recovery system 200 may further include an extraction device 20 upstream of the thin film dryer 10. The extraction device 20 is configured to separate an extract 4 containing organic solvent-soluble lignin from a solid material 5 containing lignin using a mixed solvent of an organic solvent 2 and water 1. By including the extraction device 20, the recovery system 200 can obtain an extract 4 containing organic solvent-soluble lignin from the solid material 5 containing lignin.

[0041] Examples of the extraction device 20 include known extraction devices such as a rotocel type extraction device, an extraction device consisting of a batch type stirring tank, and a line mixer type extraction device using a screw feeder or the like.

[0042] The organic solvent used in the mixed solvent is preferably one having affinity (hydrophilicity) for water, and from the viewpoint of improving the extraction rate of organic solvent-soluble lignin, the solubility in water at 20°C is preferably 90 g / L or more, more preferably 100 g / L or more, and even more preferably 120 g / L or more.

[0043] In addition, the organic solvent preferably has an SP value of 8 or more and 23 or less, more preferably 8 or more and 16 or less, and even more preferably 9 or more and 15 or less, from the viewpoint of improving the extraction rate of organic solvent-soluble lignin.

[0044] In addition, the "SP value" here means the solubility parameter (SP value), and is the value δ [(cal / cm 2 )] calculated based on the following Fedors formula using the Fedors method (Reference 1: "Fedors RF, "A Method for Estimating Both the Solubility Parameters and Molar Volumes of liquids", Polymer Engineering and Science, Vol. 14, No. 2, p147-154, 1974."). 3 ) 1 / 2 ] and is calculated from the square root of the ratio of the sum of the vaporization energies of the atoms or atomic groups in the chemical structure of the compound (Δei) to the sum of the molar volumes (Δvi).

[0045] Fedors formula: δ=(ΣΔei / ΣΔvi) 1 / 2

[0046] Specific examples of such organic solvents include alcohols, nitriles, ethers, and ketones. These organic solvents may be used alone or in combination of two or more.

[0047] Examples of alcohols include methanol, ethanol, diethylene glycol, n-propanol, isopropanol, 2-butanol, isobutanol, and t-butyl alcohol.

[0048] An example of the nitriles is acetonitrile.

[0049] Examples of ethers include dioxane and tetrahydrofuran (THF).

[0050] Examples of the ketones include acetone and methyl ethyl ketone.

[0051] Among them, the organic solvent is preferably methanol, ethanol, THF, or acetone, and more preferably acetone, because it has a high extraction rate of organic solvent-soluble lignin. These organic solvents have low solubility for saccharified biomass such as glucose and xylose, and furthermore do not dissolve cellulose, hemicellulose, etc., and therefore can efficiently extract lignin.

[0052] In the mixed solvent, the ratio of water to the organic solvent is preferably more than 0 / 100 and not more than 40 / 60 by mass, more preferably from 10 / 90 to 40 / 60, and even more preferably from 20 / 80 to 40 / 60. By having the ratio within the above range, the organic solvent-soluble lignin can be extracted more efficiently.

[0053] The water in the mixed solvent includes the water contained in the solid material containing lignin. For example, by adding about 4 to 5 parts by mass of an organic solvent (preferably acetone or ethanol) having a concentration of 90% by mass to 1 part by mass of the solid material having a water content of 60% by mass, extraction can be performed under the above-mentioned range of the ratio of water to the organic solvent.

[0054] The amount of the mixed solvent added may be 2 to 20 times, or 5 to 15 times, the dry mass of the lignin-containing solid material, in terms of mass ratio, but is not limited thereto.

[0055] The extraction time (the time for mixing and stirring the lignin-containing solid material and the mixed solvent) can be, for example, 30 minutes or more and 240 minutes or less, but is not limited thereto. The extraction temperature (the temperature conditions until the organic solvent-soluble lignin is dissolved in the organic solvent and an extract is obtained) can be performed under mild temperature conditions below the boiling point of the organic solvent used, for example, at room temperature (specifically, about 15°C to 35°C). Other conditions such as the stirring speed can be appropriately set depending on the amount of the lignin-containing solid material and the mixed solvent.

[0056] The mixture of the lignin-containing solid 5 and the mixed solvent obtained in the extraction device 20 is sent to the subsequent solid-liquid separation device 30 via piping 21, as necessary, to separate the extract 4.

[0057] [Solid-liquid separator] The recovery system 200 may further include a solid-liquid separator 30 upstream of the thin film dryer 10 and downstream of the extractor 20. The solid-liquid separator 30 is configured to separate an extract 4 containing organic solvent-soluble lignin from a mixture of a lignin-containing solid 5 and a mixed solvent. By including the solid-liquid separator 30, the recovery system 200 can obtain the extract 4 containing organic solvent-soluble lignin.

[0058] As the solid-liquid separator 30, a known device capable of separating solids and liquids can be used, and examples thereof include, but are not limited to, a filter, a vibrating sieve, a centrifuge, a screw press, and the like.

[0059] The extract 4 obtained in the solid-liquid separator 30 is sent via a pipe 31 to the subsequent thin-film dryer 10 .

[0060] Fig. 4 is a schematic diagram showing a recovery system for organic solvent-soluble lignin according to a third embodiment of the present invention. The recovery system 300 shown in Fig. 4 differs from the recovery system 200 shown in Fig. 3 in that a volatilization tank 40 is further provided upstream of the thin film dryer 10 and downstream of the extraction device 20 and the solid-liquid separation device 30. In the recovery system 300, the extract 4 obtained in the solid-liquid separation device 30 is sent to the subsequent volatilization tank 40 via a pipe 31.

[0061] [Evaporation tank] The volatilization tank 40 is configured to volatilize the volatile components 7 from the extract 4 and concentrate the extract 4 to produce a concentrate of the extract (hereinafter, may be simply referred to as a "concentrate"). By including the volatilization tank 40, the recovery system 300 can recover the organic solvent-soluble lignin more efficiently while reducing energy consumption compared to the case where the organic solvent-soluble lignin is dried using only a thin film dryer.

[0062] The volatilization tank 40 may be of a batch type or a continuous type. In order to heat the extract, the volatilization tank 40 may be provided with a hot water circulating jacket, an electric heating wire, a steam tube, or the like on the outside of the device. The heat source for heating may be a known source such as electricity, steam, or combustion gas. The stirring method of the volatilization tank 40 may be such that shelves (trays) are provided inside the tank in order to increase the volatilization area, or a multi-effect tank type consisting of multiple layers may be used.

[0063] The treatment temperature in the volatilization tank 40 can be, for example, 10°C or higher and 100°C or lower, and can be 30°C or higher and 80°C or lower. The treatment time in the volatilization tank 40 can be the time until the above-mentioned coagulation and precipitation of lignin in the extract begins. As shown in the examples described later, the time until the above-mentioned coagulation and precipitation of lignin begins can be set using the content of the organic solvent relative to the total mass of water and the organic solvent in the extract as an index. The time can be set to volatilize a part of the mixed solvent until the content of the organic solvent becomes 50% by mass or higher and 60% by mass or lower, preferably 51% by mass or higher and 57% by mass or lower, and more preferably 53% by mass or higher and 55% by mass or lower. By having the content of the organic solvent within the above range, the extract can be concentrated until the above-mentioned coagulation and precipitation of lignin begins, and the organic solvent-soluble lignin can be recovered more efficiently while reducing energy consumption than when the organic solvent-soluble lignin is dried only by a thin-film dryer. The specific treatment time for determining the content of such organic solvent can be appropriately set depending on the treatment temperature and the treatment amount of the extract. For example, when 40 L of extract containing 3.5 mass% organic solvent-soluble lignin, 34.0 mass% water, and 62.5 mass% organic solvent relative to the total mass of the extract is treated at 30° C. or higher and 80° C. or lower, the treatment time can be about 0.01 hours or longer and 24 hours or shorter.

[0064] The concentrated liquid obtained in the volatilization tank 40 is sent to the subsequent thin-film dryer 10 via a pipe 41.

[0065] Fig. 5 is a schematic diagram showing a recovery system for organic solvent-soluble lignin according to a fourth embodiment of the present invention. The recovery system 400 shown in Fig. 5 differs from the recovery system 300 shown in Fig. 4 in that a distillation apparatus (distillation column) 50 is further provided as a separation apparatus downstream of the thin film dryer 10. In the recovery system 400, the volatile components 6 and 7 discharged from the thin film dryer 10 and the volatilization tank 40 via pipes 12 and 42, respectively, are joined together and sent to the distillation apparatus (distillation column) 50, which is a separation apparatus, via pipe 43.

[0066] [Separation device] The separation device is configured to separate water and an organic solvent from the volatile components discharged from the thin-film dryer and the volatilization tank. By providing the separation device, the recovery system of this embodiment can recover a regenerated solvent 8 consisting of water and an organic solvent or only an organic solvent. The recovered regenerated solvent 8 can be reused in the extraction device 20.

[0067] The separation apparatus may be any apparatus capable of recovering water and an organic solvent from a volatile component, such as a distillation apparatus (distillation column), etc. The distillation apparatus may be of a simple distillation type, may have a structure with shelves (trays) inside, or may have a structure filled with a packing material.

[0068] When a distillation apparatus with internal shelves (trays) is used, the steam rising from the bottom of the tower heats the volatile components introduced and the internal reflux liquid flowing down from the top of the tower, generating steam containing a lot of organic solvents with low boiling points. The steam from the bottom of the tower contains a lot of water with a high boiling point, and this condenses. That is, on each shelf (tray), heat exchange and material exchange take place, and the lower the boiling point component becomes richer as the top of the tower is approached, and conversely, the higher the boiling point component becomes richer as the bottom of the tower is approached.

[0069] The overhead fraction, which is rich in low boiling point components, is taken out of the apparatus via pipe 52a and condensed in a condenser (condenser) 53 or the like. The condensed overhead fraction is returned to the distillation apparatus at a constant rate via a regulator and a control valve that adjust the reflux rate by a reflux pump or the like via pipe 52b. The reflux pump, regulator, and control valve are sometimes collectively referred to as a reflux rate control mechanism 55. The remaining overhead fraction is withdrawn at a constant flow rate as the regenerated solvent 8 to be reused in the extraction apparatus 40 via a regulator and a control valve (not shown) that adjust the flow rate of the remaining overhead fraction. The regulator and control valve that adjust the flow rate of the remaining overhead fraction are sometimes collectively referred to as a regenerated solvent flow rate control mechanism (not shown). The withdrawal flow rate can be changed by the regenerated solvent flow rate control mechanism depending on the amount of regenerated solvent 8 used in the extraction apparatus. The regenerated solvent 8 here may be a mixed solvent of an organic solvent and water, or may be a solvent consisting of an organic solvent only, but it is preferable that it is a mixed solvent of an organic solvent and water because it does not require the use of additional feed water.

[0070] Meanwhile, at the bottom of the tower, heating steam is supplied to the reboiler 58 at a constant flow rate by a regulator and control valve that adjust the flow rate of the reboiler heating steam, and a constant amount of heat is supplied to the distillation apparatus 50. These regulators and control valves are sometimes collectively referred to as the reboiler boil-up rate adjustment mechanism 58. A constant amount of water-rich steam is generated from the reboiler as this heat source, and comes into contact with the reflux liquid from above on each tray inside the tower, exchanging heat and materials while performing the distillation operation. The amount of this generated steam is adjusted by the reboiler boil-up rate, which is determined by the amount of reboiler heating steam, which is the heat source.

[0071] The distillation apparatus 50 preferably has a control unit 51 that controls the reboiler boiling amount and the reflux amount so that the content ratio of water and organic solvent in the distillate is within a predetermined range. By having the distillation apparatus 50 have the control unit 51, the regenerated solvent 8 having a content ratio of water and organic solvent in a predetermined range can be reused in the extraction apparatus 20. The control unit 51 controls the reflux amount adjustment mechanism 55 and the reboiler boiling amount adjustment mechanism 58 to control the reflux amount and the reboiler boiling amount, respectively, based on the measurement result of the content ratio of water and organic solvent in the regenerated solvent 8 so that the content ratio of water and organic solvent is within a predetermined range. Specifically, by controlling the reflux amount adjustment mechanism 55 to increase the reflux amount, the content ratio of the organic solvent in the regenerated solvent 8 can be increased, while the content ratio of the organic solvent in the regenerated solvent 8 can be decreased by decreasing the reflux amount. In addition, by controlling the reboiler boiling amount adjustment mechanism 58 to increase the reboiler boiling amount, the water content ratio in the regenerated solvent 8 can be increased, while by decreasing the reboiler boiling amount, the water content ratio in the regenerated solvent 8 can be decreased.

[0072] The content ratio of water and organic solvent may be such that the ratio of water to organic solvent, in mass ratio, is within the range exemplified for the above extraction apparatus, or may be such that the ratio of water to organic solvent in the mixed solvent in the extraction apparatus 20 is within the range exemplified for the above extraction apparatus, taking into account the amount of water in the lignin-containing solid material used as the raw material and the amount of feed water. Among these, since feed water is not required, the content ratio of water and organic solvent in the distillate is preferably such that the ratio of water to organic solvent in the mixed solvent in the extraction apparatus 20 is within the range exemplified for the above extraction apparatus, taking into account the amount of water in the lignin-containing solid material used as the raw material. For example, the ratio of water to organic solvent can be set to the range exemplified in the above extraction device by mixing 40 parts by mass of lignin-containing solid material having a water content of 50% by mass relative to the total mass of the solid material with 40 parts by mass to 160 parts by mass of regenerating solvent having a mass ratio of water to organic solvent of 80 / 20 to 60 / 40. Such a range may be stored in the control unit in advance, or the control unit may calculate the ratio of water to organic solvent based on the value detected while operating the extraction device 20.

[0073] The recovery system 400 may further include a pipe 54 configured to send the distillate obtained in the distillation apparatus 50 to the extraction apparatus 20. By including the pipe 54, the recovery system 400 can send the regenerated solvent 8 recovered in the distillation apparatus 50 to the extraction apparatus for reuse.

[0074] The recovery system of this embodiment is not limited to the recovery system shown in Figures 2 to 5, and may be one in which some of the configurations shown in Figures 2 to 5 have been changed or removed, or other configurations may be added to those described above, within the scope that does not impair the effects of the present invention. For example, in the recovery system shown in Figures 2 to 5, a saccharification apparatus may be provided upstream of the extraction apparatus. There are no particular limitations on the saccharification apparatus, and any known saccharification apparatus may be used. Specific examples include saccharification apparatuses of the stirring type, aeration stirring type, bubble column type, fluidized bed type, and packed bed type. In addition, the saccharification apparatus may be provided with a temperature control device, such as a hot water circulation jacket, on the outside of the apparatus in order to keep the temperature inside the apparatus constant. 2 to 5, a second solid-liquid separation device may be provided downstream of the saccharification device and upstream of the extraction device. Examples of the second solid-liquid separation device include those exemplified in the above "solid-liquid separation device." In addition, for example, in the recovery system shown in Figures 2 to 5, a pretreatment device may be provided upstream of the saccharification device. The pretreatment device is preferably a reaction vessel used in the dilute sulfuric acid digestion method. The reaction vessel used in the dilute sulfuric acid digestion method is not particularly limited as long as it is a steam supply type, and examples thereof include a heating and pressure device such as an acid-resistant autoclave, or an acid-resistant heating and pressure vessel, further integrated with a screw feeder, which can perform continuous treatment, and the like.

[0075] <Method for recovering organic solvent-soluble lignin> The recovery method of the present embodiment includes a drying step. By including the drying step, the recovery method of the present embodiment can stably recover solid organic solvent-soluble lignin that does not contain water and does not recondense.

[0076] [Drying process] In the drying step, an extract containing organic solvent-soluble lignin extracted from a solid material containing lignin with a mixed solvent of an organic solvent and water is dried to form a thin-film-like dried material containing solid organic solvent-soluble lignin.

[0077] The drying method may be, for example, the above-mentioned method using a thin-film dryer.

[0078] The drying time may be short enough so that lignin does not precipitate, and can be appropriately selected depending on the drying temperature, etc., but can be, for example, from about 2 seconds to about 60 seconds, or from 2.5 seconds to about 30 seconds.

[0079] The drying temperature can be set so that the temperature of the heat transfer surface of a member having a heat transfer surface of the thin film dryer is, for example, 80°C or higher and 130°C or lower.

[0080] Moreover, the volatile components discharged in the drying step can be reused in the recycling step described below.

[0081] The recovery method of this embodiment may further include a collection step after the drying step.

[0082] [Collection process] In the collecting step, a thin film-like dried material containing solid organic solvent-soluble lignin is collected.

[0083] Examples of the collection method include a method using the scraping mechanism described above. That is, the collection process can also be called a scraping process. By scraping and collecting the thin-film dried material formed on the heat transfer surface of the thin-film dryer, the thin-film dried material is crushed, and powdery organic solvent-soluble lignin can be collected.

[0084] In addition, the drying step and the collecting step are preferably performed alternately and continuously. As described above, for example, by rotating a member including a heat transfer surface, the extraction liquid can be dried and the dried product can be scraped off and collected efficiently during one rotation of the member including a heat transfer surface, and organic solvent-soluble lignin can be continuously collected.

[0085] The recovery method of the present embodiment may further include an extraction step before the drying step. By including the extraction step, the recovery method of the present embodiment can obtain an extract containing organic solvent-soluble lignin from the solid material containing lignin.

[0086] [Extraction process] The extraction step is a step of mixing a solid material containing lignin with a mixed solvent of an organic solvent and water, and separating an extract containing organic solvent-soluble lignin.

[0087] The extraction method may be any method in which a solid material containing lignin is mixed and stirred with a mixed solvent of an organic solvent and water to dissolve the organic solvent-soluble lignin in the organic solvent. For example, the apparatus exemplified in the above "extraction apparatus" may be used.

[0088] The various extraction conditions, such as the composition of the mixed solvent used, the amount of the mixed solvent added, the extraction time, and the extraction temperature, are the same as those exemplified in the above "Extraction Apparatus."

[0089] Examples of a method for separating an extract containing organic solvent-soluble lignin from a mixture of a lignin-containing solid and a mixed solvent of an organic solvent and water include a method in which the mixture is allowed to stand for a predetermined time, whereby the undissolved solids precipitate and move to the lower layer, and the liquid moves to the upper layer, and then only the liquid component in the upper layer is extracted. Alternatively, examples of a method in which an extract containing organic solvent-soluble lignin is separated from the mixture using a solid-liquid separation method are included. Among these, a method in which an extract containing organic solvent-soluble lignin is separated from the mixture using a solid-liquid separation method is preferred.

[0090] That is, the recovery method of the present embodiment may further include a solid-liquid separation step after the extraction step and before the drying step.

[0091] [Solid-liquid separation process] In the solid-liquid separation step, an extract containing organic solvent-soluble lignin is separated from a mixed liquid of a solid containing lignin and a mixed solvent of an organic solvent and water by a solid-liquid separation method. By including the solid-liquid separation step, the recovery method of the present embodiment can easily and efficiently separate the extract from the mixed liquid.

[0092] As a method for solid-liquid separation, a known method capable of separating a solid component from a liquid component can be used. Examples of the method include, but are not limited to, filtration using a filter, a vibrating sieve, or the like, centrifugation, and separation using a screw press.

[0093] The recovery method of the present embodiment may further include a volatilization step before the drying step and after the extraction step (after the solid-liquid separation step).

[0094] [Evaporation process] In the volatilization step, a part of the mixed solvent contained in the extract is volatilized. By including the volatilization step, the recovery method of the present embodiment can recover the organic solvent-soluble lignin more efficiently while reducing the amount of energy consumption, compared to the case where the organic solvent-soluble lignin is dried only by the drying step described above.

[0095] The various conditions in the volatilization step, such as the treatment time and the treatment temperature, are the same as those exemplified in the "volatilization tank" above.

[0096] In addition, the volatile components obtained by volatilizing a part of the mixed solvent contained in the extract in the volatilization step can be used in the reuse step described below.

[0097] The recovery method of the present embodiment may further include a separation step after the drying step.

[0098] [Separation process] In the separation step, water and an organic solvent are separated from the volatile components discharged in the drying step and the volatilization step. The recovery method of this embodiment includes a separation step, and thus can recover a regenerated solvent consisting of water and an organic solvent or only an organic solvent from the volatile components. In addition, the recovered regenerated solvent can be reused in the above-mentioned extraction step. The method of separating water and an organic solvent by distillation is the same as that exemplified in the above "separation device".

[0099] The separation method may be, for example, a distillation method, etc. That is, when the separation method is a distillation method, the separation step may also be called a distillation step.

[0100] The recovery method of this embodiment may further include a recycling step after the distillation step.

[0101] [Reuse process] In the reuse step, the distillate (also called regenerated solvent) obtained in the distillation step is reused in the extraction step.

[0102] In this case, in the distillation step, the reboiler boiling rate and the reflux rate are controlled so that the content ratio of water to the organic solvent is within a predetermined range. The method of controlling the reboiler boiling rate and the reflux rate so that the content ratio of water to the organic solvent is within a predetermined range is the same as that exemplified in the "separation apparatus" above.

[0103] In the reuse step, the supply amount of the distilled liquid (regenerated solvent) obtained in the distillation step and the supply amount of water are controlled so that the content ratio of water and organic solvent in the mixed liquid used in the extraction step is the mass ratio of the content of water to the organic solvent exemplified in the above "extraction apparatus". The supply amount of the distilled liquid (regenerated solvent) can be changed by the above-mentioned regenerated solvent flow rate control mechanism. Similarly, the supply amount of water can be changed by a regulator and a control valve (collectively sometimes referred to as "supply water flow rate control mechanism") that adjust the flow rate of the supply water. Among these, since it is not necessary to use new water, it is preferable to control only the supply amount of the distilled liquid (regenerated solvent) without using supply water (i.e., the supply amount of water is substantially zero).

[0104] [Other processes] The recovery method of the present embodiment may further include other steps in addition to the steps described above.

[0105] (saccharification process) For example, the recovery method of this embodiment may further include a saccharification step prior to the extraction step. In the saccharification step, a saccharification reaction is carried out using enzymes and cellulose and hemicellulose contained in the lignin-containing solid matter (lignocellulosic biomass) as substrates. By including the saccharification step, the recovery method of this embodiment can effectively utilize the residue (saccharification residue) remaining after removing useful components contained in the lignocellulosic biomass. The enzymes referred to here are mainly saccharification enzymes.

[0106] As used herein, the term "saccharifying enzyme" includes cellulase that breaks down cellulose, hemicellulase that breaks down hemicellulose, amylase that breaks down starch, and the like.

[0107] The cellulase may be any that decomposes cellulose into monosaccharides or oligosaccharides such as glucose, and examples thereof include those having at least one of the activities of endoglucanase (EG), cellobiohydrolase (CBH), and β-glucosidase (BGL). From the viewpoint of enzyme activity, an enzyme mixture having each of these activities is preferred.

[0108] The hemicellulase may be any enzyme that decomposes hemicellulose into monosaccharides or oligosaccharides such as xylose, and examples thereof include enzymes having at least one of the activities of xylanase, xylosidase, mannanase, galactosidase, glucuronidase, and arabinofuranosidase. From the viewpoint of enzyme activity, an enzyme mixture having each of these activities is preferred.

[0109] The origin of these saccharifying enzymes such as cellulase and hemicellulase is not limited, and for example, saccharifying enzymes such as cellulase and hemicellulase derived from microorganisms such as those of the genus Trichoderma, Acremonium, Aspergillus, Bacillus, Pseudomonas, Penicillium, Aeromonas, Irpex, Sporotrichum, and Humicola can be used.

[0110] The saccharification temperature is preferably from 45° C. to 70° C., more preferably from 45° C. to 55° C., and particularly preferably from 50° C. The saccharification time is preferably from 12 hours to 120 hours, more preferably from 24 hours to 96 hours, and even more preferably from 24 hours to 72 hours.

[0111] (Second solid-liquid separation step) For example, the recovery method of this embodiment may further include a second solid-liquid separation step before the extraction step and after the saccharification step. In the second solid-liquid separation step, the saccharification treatment product obtained in the saccharification step is subjected to solid-liquid separation to separate the saccharification solution, which is a liquid fraction, and the saccharification residue, which is a solid fraction, to obtain the saccharification residue. By including the second solid-liquid separation step, the recovery method of this embodiment can easily separate the saccharification solution and the saccharification residue. Examples of the solid-liquid separation method include the same methods as those exemplified in the above "solid-liquid separation step".

[0112] The saccharified solution obtained in the second solid-liquid separation step may be purified by removing impurities from the saccharified solution and sold as refined molasses, or may be used to produce useful components other than organic solvent-soluble lignin, which are produced by microbial fermentation of the saccharified solution.

[0113] The useful components different from organic solvent-soluble lignin refer to compounds produced by microorganisms such as yeast ingesting monosaccharides and oligosaccharides obtained by decomposing herbaceous biomass. Specific examples of useful components include alcohols such as ethanol, butanol, 1,3-propanediol, 1,4-butanediol, and glycerol; organic acids such as pyruvic acid, succinic acid, malic acid, itaconic acid, citric acid, and lactic acid; nucleosides such as inosine and guanosine; nucleotides such as inosinic acid and guanylic acid; and diamine compounds such as cadaverine. When the compound obtained by fermentation is a monomer such as lactic acid, it may be converted into a polymer by polymerization. Among them, ethanol is preferred as a useful component different from organic solvent-soluble lignin.

[0114] (Pretreatment process) For example, the recovery method of the present embodiment may further include a pretreatment step prior to the saccharification step. The pretreatment step is a step of pretreating a solid matter containing lignin (lignocellulosic biomass) in order to efficiently carry out a saccharification reaction in the subsequent saccharification step. By including the pretreatment step, the recovery method of the present embodiment can efficiently carry out the subsequent saccharification step.

[0115] Examples of the pretreatment method of lignocellulosic biomass include a steam-only cooking method, a method using an ionic liquid, and a pulverization method using a mill. In addition, in the pretreatment step, an acid or an alkali may be mixed as necessary. The acid is selected from sulfuric acid (including dilute sulfuric acid), hydrochloric acid, nitric acid, phosphoric acid, and the like, and these may be used alone or in combination. Among these, sulfuric acid, which is inexpensive and easily available, is particularly preferable for industrial use. The alkali is selected from sodium hydroxide, potassium hydroxide, and ammonia, and these may be used alone or in combination. Among these, the dilute sulfuric acid cooking method using dilute sulfuric acid is preferable as the pretreatment method. EXAMPLES

[0116] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0117] [Example 1] <Preparation of organic solvent-soluble lignin-containing extract> Napier grass (165 kg-dry), a herbaceous biomass, was pretreated by dilute sulfuric acid cooking and then saccharified using a saccharification enzyme (a mixture of cellulase and hemicellulase). The resulting saccharification liquid was then separated into solid and liquid using a centrifuge, and saccharification residue (29 kg-dry) was obtained. The resulting saccharification residue was then dried to obtain a dried saccharification residue. The resulting dried saccharification residue (3.5 kg-dry) was added to 31.5 kg of acetone or a mixed solvent of ethanol and water (mixture ratio: 60 / 40 by mass), stirred, and then subjected to solid-liquid separation using a centrifuge to obtain an extract and an extraction residue.

[0118] <Drying of organic solvent-soluble lignin using a thin-film dryer> Next, the extract obtained above was dried using a disk dryer (see Fig. 6A and Fig. 6B) under the following drying conditions.

[0119] (Drying conditions) Rotation speed: 3 rpm to 20 rpm Steam temperature: 110℃ Disc diameter: 540mm Effective area (both sides): 0.4m 2 Target sample: Extract Extract application speed: 15g / sec

[0120] The disk dryer was set to a rotation speed of 20 rpm, and the disk rotated once in about 3 seconds. The solvent in the extract applied to the disk surface volatilized before the above-mentioned lignin aggregated and precipitated, making it possible to recover solid, organic solvent-soluble lignin (powder).

[0121] [Example 2] <Study on solvent volatilization conditions for organic solvent-soluble lignin-containing extract> An extract containing organic solvent-soluble lignin was prepared using the same method as in Example 1. The composition of the extract was 20% by mass of organic solvent-soluble lignin and 80% by mass of solvent relative to the total mass of the extract. The composition of the solvent was 60% by mass of acetone or ethanol (48% by mass relative to the total mass of the extract) and 40% by mass of water (32% by mass relative to the total mass of the extract).

[0122] Next, 1800 g of the extract was placed in a beaker, heated while stirring with a stirrer, and the solvent was evaporated over time at 50°C. The volatile components were continuously collected, and the masses of water and organic solvent (acetone or ethanol) in the collected volatile components were measured. The percentage of the mass of the organic solvent (acetone or ethanol) in the collected volatile components relative to the total mass of the solvent used in the volatilization test was calculated as the volatilization rate (mass%, wt%).

[0123] FIG. 7 is a graph showing the change over time in the volatilization rate of the organic solvent (acetone or ethanol) in the extract. Precipitates were observed on the liquid surface when the volatilization rate of acetone was 15% by mass, and when the volatilization rate of ethanol was 31% by mass. At this time, the content of acetone in the extract remaining in the beaker was 55% by mass relative to the total mass of the extract remaining in the beaker. The content of ethanol in the extract remaining in the beaker was 53% by mass relative to the total mass of the extract remaining in the beaker.

[0124] The time when the precipitate appears on the liquid surface is considered to be just before the start of coagulation and precipitation of lignin through water. It was presumed that by volatilizing the solvent from the extract in the volatilization tank and concentrating the extract up to the above-mentioned time, solid organic solvent-soluble lignin could be recovered in an energy-efficient manner. [Industrial Applicability]

[0125] According to the system and method for recovering organic solvent-soluble lignin of the present embodiment, it is possible to provide a system and method for recovering organic solvent-soluble lignin that can stably obtain solid lignin. [Explanation of symbols]

[0126] 1: Water (supply water) 2: Organic solvent 3: Organic solvent soluble lignin 3a: Solid organic solvent-soluble lignin 4:Extract liquid 5: Solids containing lignin 6,7: Volatile components 8: Regeneration solvent 9: Column bottom waste liquid 10: Thin film dryer 11, 12, 21, 31, 41, 42, 43, 52a, 52b, 52c, 54, 56a, 56b, 56c, 56d, 57: Piping 20:Extraction device 30: Solid-liquid separator 40: Evaporation tank 50: Distillation apparatus (distillation column) 51: Control unit 53: Condenser 55: Reflux amount adjustment mechanism 58: Reboiler 59: Reboiler boiling amount adjustment mechanism 100, 200, 300, 400: Recovery system for organic solvent-soluble lignin

Claims

1. 1. A system for recovering organic solvent soluble lignin, comprising: A recovery system including a thin-film dryer configured to dry an extract extracted from a solid material containing lignin with a mixed solvent of an organic solvent and water, and form a thin-film dried material containing solid organic solvent-soluble lignin.

2. The recovery system of claim 1 , wherein the thin film dryer is a conductive heat transfer dryer.

3. The recovery system according to claim 1 or 2, further comprising an extractor upstream of the thin-film dryer, the extractor configured to separate the extract from the solid matter by the mixed solvent.

4. 1. A method for recovering organic solvent-soluble lignin, comprising: A recovery method comprising a drying step of drying an extract obtained by extracting a solid material containing lignin with a mixed solvent of an organic solvent and water to form a thin-film-like dried material containing solid organic solvent-soluble lignin.

5. The method according to claim 4 , wherein the drying step is carried out using a thin film dryer.

6. The recovery method according to claim 5 , wherein the thin film dryer is a conductive heat transfer dryer.

7. The method according to any one of claims 4 to 6, further comprising a collection step of collecting the dried product after the drying step.

8. The recovery method according to any one of claims 4 to 7, further comprising an extraction step of mixing the solid with the mixed solvent and separating the extract before the drying step.

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