System and method for recovering 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, which is made from plant resources, has been attracting attention from the perspectives of global warming countermeasures and the effective utilization of waste. Generally, carbohydrates such as sugarcane and starch such as corn are widely 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 poses the risk of competition with food or feed uses and resulting in a rise in raw material prices.

[0003] Therefore, technological development is underway 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, a complex of aromatic polymers such as lignin and hemicellulose.

[0004] Ethanol production using lignocellulosic biomass as a feedstock involves a pretreatment process in which the biomass feedstock is thermochemically pretreated; a saccharification process in which the biomass after the pretreatment process is enzymatically treated to produce a saccharified solution; a fermentation process in which a microbial culture solution is added to the saccharified solution obtained in the saccharification process to carry out ethanol fermentation; and a purification process in which ethanol is separated from the fermented solution obtained in the fermentation process by distillation or other methods. This ethanol production process poses a problem: a large amount of fermentation residue is generated because lignin remains as a solid. This fermentation residue is generally disposed of in boilers or through methane fermentation in an attached factory, and is currently not effectively utilized.

[0005] Similarly, in the papermaking process using non-edible biomass as a raw material, lignin-based products (black liquor, lignin sulfonates) are generated as residues, and technologies for their effective utilization have been developed over many years. However, because the lignin is sulfonated or chlorinated during the chemical decomposition process of the biomass, it is difficult to utilize, and most of it is only used as fuel for boiler heat sources.

[0006] On the other hand, lignin decomposition can produce phenol derivatives and other compounds, which can be used as raw materials for chemical industrial products such as resin raw materials, composite materials, surfactants, etc. Therefore, there is a need for the development of a method for efficiently producing lignin decomposition products.

[0007] Patent Document 1 discloses a method for producing lignin degradation products by treating lignin-containing biomass with a mixed solvent containing water and alcohol in a molar ratio of 1 / 1 to 20 / 1. Patent Document 2 discloses a method for producing low-molecular-weight lignin by heating 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 lignin degradation products by pretreating lignin-containing biomass with a combination of hydrothermal treatment and pulverization, enzymatically saccharifying the pretreated biomass, subjecting the resulting enzymatic saccharification residue to further hydrothermal treatment in an autoclave, obtaining a solid from solid-liquid separation of the resulting product, and dissolving the solid in an organic solvent. Patent Document 4 discloses a method for producing lignin degradation products by enzymatically saccharifying 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 lignin degradation products, and then subjecting the heat-treated liquid to solid-liquid separation to remove insoluble matter. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-015439 [Patent Document 2] JP 2016-050200 A [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-157792 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-241391 Summary of the Invention [Problem to be solved by the invention]

[0009] Lignin obtained using 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 recover solid lignin from the solution by adding the solution to a stirring tank equipped with a heating jacket, volatilizing the solvent over time by heat concentration, and then recovering solid lignin from the solution. However, due to the influence of residual water and organic solvents during heat 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 view of the above circumstances, and provides a system and method for recovering organic solvent-soluble lignin, which enable the stable production of 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 to form a thin-film dried material containing solid organic solvent-soluble lignin. (2) The recovery system according to (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 extractor upstream of the thin-film dryer, the extract being configured to separate the extract from the solid matter using the mixed solvent. (4) The recovery system according to (3), further comprising a volatilization 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 is further provided. The recovery system according to (6), wherein the distillation apparatus has a control unit that controls the reboiler boil-up rate and reflux rate so that the content ratio of water and organic solvent in the distillate is within a predetermined range.

[0012] (8) A method for recovering organic solvent-soluble lignin, comprising: 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 recovery method according to (8), further comprising a collection step of collecting the dried product after the drying step. (10) The recovery method according to (8) or (9), further comprising an extraction step of mixing the solid material with the mixed solvent and separating the extract before the drying step. (11) The recovery 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 recovery method according to (11), wherein in the volatilization step, a portion of the mixed solvent is volatilized until the content of the organic solvent in the extract is 50% by mass or more but less than 60% by mass, based on the total mass of water and the organic solvent in the extract. (13) The recovery 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 recovery 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, (14) The recovery method according to (14), wherein in the distillation step, the reboiler boil-up rate and the reflux rate are controlled so that the content ratio of water to the organic solvent in the distillate falls within a predetermined range. (16) The method according to (15), wherein the amount of the distillate supplied and the amount of water supplied are controlled in the recycling step so that the ratio of the water content to the organic solvent content in the mixed solvent used in the extraction step is the same. [Effects 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 explanation of the drawings]

[0014] [Figure 1A] FIG. 1 is a diagram schematically illustrating changes in a solution when the solution containing water, an organic solvent, and organic solvent-soluble lignin is dried by a conventional heating and concentration method. [Figure 1B] FIG. 1 is a diagram schematically illustrating changes in a solution containing water, an organic solvent, and organic solvent-soluble lignin when the solution is dried using a thin-film dryer. [Figure 2] FIG. 1 is a schematic diagram showing a system for recovering organic solvent-soluble lignin according to a first embodiment of the present invention. [Figure 3] FIG. 1 is a schematic diagram showing a system for recovering organic solvent-soluble lignin according to a second embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram showing a system for recovering organic solvent-soluble lignin according to a third embodiment of the present invention. [Figure 5] FIG. 1 is a schematic diagram showing a system for recovering organic solvent-soluble lignin according to a fourth embodiment of the present invention. [Figure 6A]FIG. 1 is a vertical cross-sectional view of a disk dryer according to a first embodiment. [Figure 6B] FIG. 1 is a side view of a disk dryer according to a 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 INVENTION

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

[0016] <Lignocellulosic biomass> An example of a 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 referred to as woody biomass), herbaceous plants (also referred to as herbaceous biomass), processed products thereof, and waste products thereof. Pulverized lignocellulosic biomass may be used, and may be in any form, such as blocks, chips, or powder. The lignin-containing solid material may also be residue generated during the production of bioethanol, biobutanol, or biochemicals from cellulose and hemicellulose in lignocellulosic biomass. The residue is preferably a saccharification residue remaining after pretreating lignocellulosic biomass using a dilute sulfuric acid cooking method and further decomposing the resulting pretreated raw material using an enzymatic saccharification method.

[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, castanopsis, beech, acacia, bamboo, bamboo grass, oil palm, sago palm, etc. Among them, cedar is preferred 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. Processed materials such as plywood, fiberboard, and laminated lumber made from the above woody plants can also be used. Components dismantled after use in buildings can also be used. Processed products of lignocellulosic biomass such as paper and recycled paper can also be used.

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

[0020] Among these, herbaceous plants (herbaceous biomass) are preferred, and grass plants are more preferred, as the lignin-containing solid material used as a raw material in the recovery system and recovery method of this embodiment.

[0021] <Lignin> Generally, 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, S, and H nuclei based on its structure. A G nucleus has one methoxy group (-OCH3) at the ortho position of the phenolic skeleton, an S nucleus has two methoxy groups at the ortho position, and an H nucleus has no methoxy groups at the ortho position. Lignin in herbaceous biomass such as bagasse contains all of the H, G, and S nuclei as basic skeletons. Among lignins derived from woody biomass, lignin derived from conifers has a G nucleus as its basic skeleton, while lignin derived from broad-leaved trees has a G nucleus and an S nucleus as its 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 step described below.

[0024] <Cellulose and hemicellulose> As used herein, "cellulose" includes hexoses, which are six-carbon structural units. Thus, when cellulose is hydrolyzed, it produces hexose monosaccharides (such as glucose) and hexose oligosaccharides (such as cellobiose) in which multiple hexose 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. Therefore, 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 product.

[0028] Conventionally, attempts have been made to recover solid lignin from a solution by adding the extract to a stirring tank equipped with a heating jacket, volatilizing the solvent over time through heat concentration, and then recovering the solid lignin. Figure 1A shows a schematic diagram of the changes occurring in a solution containing water, an organic solvent, and organic-solvent-soluble lignin when the solution is dried using a conventional heat concentration method. In the solution before heating, water 1, organic solvent 2, and organic-solvent-soluble lignin 3 are uniformly dispersed. During drying using a conventional heat concentration method, the mixed solvent is gradually evaporated and removed over time, with organic solvent 2 being evaporated and removed first. This disrupts the balance of water 1, organic solvent 2, and organic-solvent-soluble lignin 3 in the solution, impairing dispersibility. The organic-solvent-soluble lignin 3 attracts and begins to aggregate. Furthermore, because the organic-solvent-soluble lignin is amphiphilic, it aggregates and precipitates while absorbing water 1. Furthermore, as drying proceeds slowly over a long period of time, the aggregation and precipitation progresses, ultimately forming a tar-like dried product containing moisture. Therefore, it is difficult to stably obtain solid organic solvent-soluble lignin.

[0029] 1B is a schematic diagram showing the changes in a solution containing water, an organic solvent, and organic-solvent-soluble lignin when it is dried using a thin-film dryer. During 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, resulting in the efficient formation of a thin-film dried product containing organic-solvent-soluble lignin 3. Therefore, by including the thin-film dryer having the above-described configuration, the recovery system of this 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 the configuration of a recovery system for organic solvent-soluble lignin according to a 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 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. Examples of the thin-film dryer 10 include those having 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 lignin aggregates and precipitates. 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 thereof include an approximately circular shape (including a perfect circle), a hollow approximately circular shape (including a hollow perfect circle), a fan shape, a circular fan shape, a polygonal shape, etc., with an approximately circular shape (including a perfect circle), a hollow approximately circular shape (including a hollow perfect circle), a fan shape, or a circular fan shape being preferred. In the case of a three-dimensional shape, examples thereof 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 able to withstand the scraping operation by the scraping mechanism described below, such as steel plated with hard chrome or electroless nickel plating.

[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 recover the thin film-like dried material formed on a heat transfer surface such as a disk surface or a drum surface. Furthermore, the scraping operation breaks down the thin film-like dried material, allowing the recovery of powdery organic solvent-soluble lignin. 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 remove the dried material from the surface.

[0034] Furthermore, the thin film dryer preferably further includes 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, for example, 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 including 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 other known components, such as 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 that has not adhered to the heat transfer surface, circulate it, and supply it to the feed pipe, and a recovery port configured to remove the dried product from the dryer. The feed pipe may have, for example, an opening type like a faucet or hose outlet, a shower type, or a spray type. Instead of the feed pipe, the thin-film dryer may be configured so that a portion of the heat transfer surface is directly immersed in a storage tank (or liquid reservoir) containing the extract while rotating.

[0036] Specific examples of thin-film dryers include conductive heat transfer dryers such as disk dryers (see Figures 6A and 6B) and drum dryers. Disk dryers are configured to spray the extract onto a steam-heated disk surface (one or both sides) and volatilize the volatile components during one rotation of the disk, resulting in drying. Drum dryers are configured to apply the extract to a steam-heated drum surface (external wall surface) and volatilize the liquid components during one rotation of the drum, resulting in drying. Disk dryers and drum dryers are usually equipped with a scraper for recovering the thin-film dried material. Disk dryers and drum dryers are classified into atmospheric and vacuum types depending on their operating pressure, but either type can be used. Drum dryers are classified into double-drum, twin-drum, and single-drum types depending on the number of drums, and 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 or 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 dryer, a disk dryer is preferred because it saves space 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 is added to the heat transfer surface are factors that can be appropriately designed by a person skilled in the art depending on the composition of the extract to be dried, the amount of the extract, 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 device 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 their description will be omitted.

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

[0041] Examples of the extractor 20 include known extractors such as a funnel cell extractor, an extractor consisting of a batch-type stirring tank, and a line mixer extractor using a screw feeder or the like.

[0042] The organic solvent used in the mixed solvent preferably has 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] Furthermore, 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] Here, the "SP value" refers to the solubility parameter (SP value), which is the value δ [(cal / cm ]] calculated based on the following Fedors formula using the Fedors method (see 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, pp. 147-154, 1974."). 3 ) 1 / 2 ] and is calculated from the square root of the ratio of the sum of the evaporation energies (Δei) of the atoms or atomic groups in the chemical structure of the compound 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 ketones include acetone and methyl ethyl ketone.

[0051] Among these, methanol, ethanol, THF, or acetone is preferred as the organic solvent because it provides an excellent extraction rate for organic solvent-soluble lignin, and acetone is more preferred. These organic solvents have low solubility for biomass saccharification products such as glucose and xylose, and furthermore do not dissolve cellulose, hemicellulose, etc., so that lignin can be efficiently extracted.

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

[0053] The water in the mixed solvent includes the water contained in the lignin-containing solid material. For example, by adding 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 water to organic solvent ratio.

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

[0055] The extraction time (the time required for mixing and stirring the lignin-containing solid material with the mixed solvent) can be, for example, 30 minutes to 240 minutes, but is not limited thereto. The extraction temperature (the temperature required for dissolving the organic solvent-soluble lignin in the organic solvent and obtaining an extract) can be a mild temperature below the boiling point of the organic solvent used, for example, room temperature (specifically, about 15°C to 35°C). Other conditions, such as the stirring speed, can be appropriately set depending on the amounts 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, any 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 to the subsequent thin-film dryer 10 via a pipe 31 .

[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 it further includes a volatilization tank 40 upstream of the thin-film dryer 10 and downstream of the extractor 20 and the solid-liquid separator 30. In the recovery system 300, the extract 4 obtained in the solid-liquid separator 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 when 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 apparatus. Known heat sources such as electricity, steam, and combustion gas can be used. The agitation method of the volatilization tank 40 may include providing shelves (trays) inside the tank 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 to 100°C, and can be 30°C to 80°C. The treatment time in the volatilization tank 40 can be the time until just before the onset of the above-mentioned aggregation and precipitation of lignin in the extract. As shown in the examples described below, the time until just before the onset of the above-mentioned aggregation and precipitation of lignin can be set using the content of the organic solvent relative to the total mass of water and organic solvent in the extract as an indicator. It can be the time during which a portion of the mixed solvent is volatilized until the content of the organic solvent becomes 50% by mass to 60% by mass, preferably 51% by mass to 57% by mass, and more preferably 53% by mass to 55% by mass. By keeping the content of the organic solvent within the above range, the extract can be concentrated to just before the onset of the above-mentioned aggregation and precipitation of lignin. This allows for more efficient recovery of organic-solvent-soluble lignin while reducing energy consumption compared to drying organic-solvent-soluble lignin using only a thin-film dryer. The specific treatment time for achieving such an organic solvent content can be set appropriately depending on the treatment temperature and the amount of extract solution to be treated. For example, when 40 L of extract solution 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 solution is treated at 30°C or higher and 80°C or lower, the treatment time can be approximately 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. Recovery system 400 shown in Fig. 5 differs from recovery system 300 shown in Fig. 4 in that it further includes a distillation apparatus (distillation column) 50 as a separation device downstream of thin film dryer 10. In recovery system 400, volatile components 6 and 7 discharged from thin film dryer 10 and volatilization tank 40 via pipes 12 and 42, respectively, are joined together and sent to distillation apparatus (distillation column) 50, which is a separation device, via pipe 43.

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

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

[0068] When a distillation apparatus with internal trays is used, the vapor rising from the bottom of the column heats the volatile components introduced and the internal reflux liquid flowing down from the top of the column, generating vapor rich in low-boiling organic solvents. The vapor from the bottom of the column condenses, containing a high-boiling water component. In other words, heat and mass exchange occur on each tray, and the column becomes richer in low-boiling components as it approaches the top, and conversely, it becomes richer in high-boiling components as it approaches the bottom.

[0069] The overhead fraction, rich in low-boiling components, is withdrawn from the top of the column 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 pipe 52b, using a reflux pump or the like, via a regulator and a control valve that adjust the reflux rate. This 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 via a regulator and a control valve (not shown) that adjust the flow rate of the remaining overhead fraction as regenerated solvent 8 to be recycled to the extraction apparatus 40. 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 adjusted by the regenerated solvent flow rate control mechanism depending on the amount of regenerated solvent 8 used in the extraction apparatus. Note that the regenerated solvent 8 referred to here may be a mixed solvent of an organic solvent and water, or may be a solvent consisting solely of an organic solvent. However, a mixed solvent of an organic solvent and water is preferred because it eliminates the need for additional feed water.

[0070] Meanwhile, at the bottom of the column, 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. Steam containing a large amount of water is generated from the reboiler as this heat source at a constant rate, and comes into contact with the reflux liquid from above on each tray within the column, exchanging heat and materials as the distillation operation takes place. The amount of steam generated is adjusted by the reboiler boil-up rate, which is determined by the amount of reboiler heating steam as a heat source.

[0071] The distillation apparatus 50 preferably includes a control unit 51 that controls the reboiler boil-up rate and the reflux rate so that the water to organic solvent content ratio in the distillate is within a predetermined range. By including the control unit 51 in the distillation apparatus 50, the regenerated solvent 8 having a water to organic solvent content ratio within a predetermined range can be reused in the extraction apparatus 20. Based on the measurement results of the water to organic solvent content ratio in the regenerated solvent 8, the control unit 51 controls the reflux rate adjustment mechanism 55 and the reboiler boil-up rate adjustment mechanism 58 to control the reflux rate and the reboiler boil-up rate, respectively, so that the water to organic solvent content ratio is within the predetermined range. Specifically, by controlling the reflux rate adjustment mechanism 55 to increase the reflux rate, the organic solvent content ratio in the regenerated solvent 8 can be increased, while by decreasing the reflux rate, the organic solvent content ratio in the regenerated solvent 8 can be decreased. In addition, by controlling the reboiler boil-up rate adjustment mechanism 58 to increase the reboiler boil-up rate, the water content ratio in the regenerated solvent 8 can be increased, while by decreasing the reboiler boil-up rate, 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, falls within the range exemplified for the above-mentioned extraction apparatus, or may be such that the ratio of water to organic solvent in the mixed solvent in extraction apparatus 20 falls within the range exemplified for the above-mentioned 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. In particular, since feed water does not need to be used, 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 extraction apparatus 20 falls within the range exemplified for the above-mentioned 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 within the range exemplified for the extraction apparatus 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 to 160 parts by mass of regenerated solvent having a water to organic solvent ratio of 80 / 20 to 60 / 40 by mass. This range can be stored in advance in the control unit, or calculated by the control unit based on a value detected by detecting the ratio of water to organic solvent in the mixed solvent while the extraction apparatus 20 is operating.

[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 deleted, or one in which other configurations have been added to those described above, within the scope that does not impair the effects of the present invention. For example, in the recovery systems 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 can be used. Specific examples include agitation type, aeration agitation type, bubble column type, fluidized bed type, and packed bed type saccharification apparatus. Furthermore, the saccharification apparatus may be provided with a temperature control device, such as a hot water circulation jacket, on the outside of the apparatus to maintain a constant temperature inside the apparatus. 2 to 5, a second solid-liquid separator may be provided downstream of the saccharification apparatus and upstream of the extraction apparatus. Examples of the second solid-liquid separator include those exemplified above for the "solid-liquid separator." 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 cooking method. The reaction vessel used in the dilute sulfuric acid cooking method is not particularly limited as long as it is a steam supply type, but examples include a heating and pressure device such as an acid-resistant autoclave, or an acid-resistant heating and pressure vessel further equipped with a screw feeder to enable continuous processing.

[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, a method using the thin film dryer described above.

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

[0079] The drying temperature can be set to a temperature condition such 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] Furthermore, 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 step can also be called a scraping step. By scraping and collecting the thin film-like dried material formed on the heat transfer surface of the thin film dryer, the thin film-like dried material is crushed, and powdery organic solvent-soluble lignin can be collected.

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

[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 above as the "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 "extraction apparatus" above.

[0089] Examples of methods 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 undissolved solids precipitate and migrate to the lower layer, and the liquid migrates to the upper layer, and then only the liquid component in the upper layer is extracted. Alternatively, examples include a method in which a solid-liquid separation method is used to separate an extract containing organic solvent-soluble lignin from the mixture. Among these, a method in which a solid-liquid separation method is used to separate an extract containing organic solvent-soluble lignin from the mixture 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 mixture of a lignin-containing solid 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 mixture.

[0092] As a method for solid-liquid separation, any known method capable of separating solids and liquids can be used, and examples thereof 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] [Volatilization process] In the volatilization step, a portion 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 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 treatment temperature, are the same as those exemplified in the "volatilization tank" above.

[0096] Furthermore, 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 this embodiment may further include a separation step after the drying step.

[0098] [Separation process] In the separation step, water and organic solvent are separated from the volatile components discharged in the drying step and the volatilization step. By including the separation step, the recovery method of this embodiment can recover a recycled solvent consisting of water and organic solvent or only organic solvent from the volatile components. In addition, the recovered recycled solvent can be reused in the extraction step described above. The method for separating water and organic solvent by distillation is the same as that exemplified in the "separation apparatus" above.

[0099] Examples of the separation method include distillation, etc. That is, when the separation method is distillation, the separation step can 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 recycling step, the distillate (also called regenerated solvent) obtained in the distillation step is reused in the extraction step.

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

[0103] Furthermore, in the recycling 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 to organic solvent in the mixed liquid used in the extraction step is the mass ratio of water to organic solvent exemplified in the "extraction apparatus" above. The supply amount of the distilled liquid (regenerated solvent) can be changed using the above-mentioned regenerated solvent flow rate control mechanism. Similarly, the supply amount of water can be changed using a regulator and a control valve that adjust the flow rate of the feed water (these may be collectively referred to as a "feed water flow rate control mechanism"). 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 feed water (i.e., the water supply amount is substantially zero).

[0104] [Other processes] The recovery method of this 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 before the extraction step. In the saccharification step, a saccharification reaction is carried out using enzymes and cellulose and hemicellulose contained in 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 lignocellulosic biomass. The enzymes referred to here are mainly saccharification enzymes.

[0106] As used herein, "saccharifying enzymes" include cellulases that decompose cellulose, hemicellulases that decompose hemicellulose, and amylases that decompose starch.

[0107] The cellulase may be any cellulase 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 enzymatic 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 enzymatic activity, an enzyme mixture having each of these activities is preferred.

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

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

[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 saccharified solution, which is a liquid fraction, and the saccharified residue, which is a solid fraction, thereby obtaining the saccharified residue. By including the second solid-liquid separation step, the recovery method of this embodiment can easily separate the saccharified solution and the saccharified residue. Examples of solid-liquid separation methods include the same methods as those exemplified in the "solid-liquid separation step" above.

[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 that are produced by microbial fermentation of the saccharified solution.

[0113] The term "useful components different from organic solvent-soluble lignin" refers 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 inosinic acid 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 can be converted into a polymer by polymerization. Among these, ethanol is a preferred useful component different from organic solvent-soluble lignin.

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

[0115] Examples of pretreatment methods for lignocellulosic biomass include steam cooking only, ionic liquids, and milling using a mill. Furthermore, in the pretreatment step, an appropriate acid or alkali may be mixed as needed. The acid may be 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 readily available, is particularly preferred for industrial use. The alkali may be 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 preferred as the pretreatment method. [Example]

[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 using a dilute sulfuric acid cooking method and then saccharified using a saccharification enzyme (a mixture of cellulase and hemicellulase). The resulting saccharified liquid was then separated into solid and liquid using a centrifuge, yielding 29 kg-dry of saccharification residue. The resulting saccharification residue was then dried to obtain a dried saccharification residue. 3.5 kg of the resulting dried saccharification residue was added to 31.5 kg of acetone or a mixed solvent of ethanol and water (mixing 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> The extract obtained above was then dried using a disk dryer (see Figures 6A and 6B) under the following drying conditions.

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

[0120] By setting the disk dryer to a rotation speed of 20 rpm, the disk rotated once in about 3 seconds, and the solvent in the extract applied to the disk surface evaporated before the above-mentioned lignin aggregates and precipitates appeared, allowing the recovery of solid, organic solvent-soluble lignin (powder).

[0121] [Example 2] <Study on solvent volatilization conditions for organic solvent-soluble lignin-containing extracts> An extract containing organic solvent-soluble lignin was prepared using the same method as in Example 1. The extract contained 20% by mass of organic solvent-soluble lignin and 80% by mass of solvent relative to the total mass of the extract. The solvent contained 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 and 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 evaporation 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 reached 15% by mass and when the volatilization rate of ethanol reached 31% by mass. At this time, the acetone content in the extract remaining in the beaker was 55% by mass relative to the total mass of the extract remaining in the beaker. Furthermore, the ethanol content 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 precipitates appeared on the liquid surface was considered to be just before the start of lignin aggregation and precipitation with the aid of water. It was therefore inferred that by concentrating the extract by volatilizing the solvent from the extract in the volatilization tank until 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: Lignin-containing solids 6,7: Volatile components 8: Regeneration solvent 9: Tower 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 obtained by extracting a solid material containing lignin with a mixed solvent of an organic solvent and water, and to 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 conduction heat transfer dryer.

3. The recovery system according to claim 1 or 2, further comprising an extractor upstream of the thin-film dryer, the extract being configured to separate the extract from the solid matter using 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 conduction heat transfer dryer.

7. The recovery 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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