JP7679063B2 - Circulation grinding processing device, circulation grinding processing method, alcohol production method, and method for producing cellulose-containing composition - Google Patents

Description

The present invention relates to a circulating grinding processing device, and in particular to a circulating grinding processing device suitable for grinding high-concentration slurry-like processing materials, a circulating grinding processing method using the circulating grinding processing device, a method for producing alcohol, and a method for producing a composition containing cellulose.

Wood biomass is composed of polysaccharides such as cellulose and hemicellulose, which are made up of many sugars bound together, and lignin, which is made up of phenols with many benzene rings. The highly structured and poorly soluble polymer composition formed by cellulose or hemicellulose and lignin is also called lignocellulose.
Cellulose exhibits crystallinity, and the fibers or aggregates formed by the assembly of cellulose are very strong. Furthermore, lignin strongly bonds and covers the strong fibers to each other, forming a very strong laminated structure. Wood materials are used as structural materials because of their strong and sturdy structure.
This strong and durable structure is an obstacle when isolating cellulose from woody biomass and when breaking down cellulose into monosaccharides. Starch, which is also a polysaccharide, does not have this strong structure and can be easily broken down into monosaccharides and converted into ethanol.

Various methods have been proposed for saccharification in the process of producing ethanol from cellulose, but they can be broadly divided into acid saccharification and enzymatic saccharification.
Acid saccharification is a method in which cellulose is directly broken down into monosaccharides using a strong acid such as sulfuric acid. This has the advantage that the reaction proceeds in a short time, but it has problems such as the generation of fermentation inhibitors due to over-decomposition, and the need for acid-resistant equipment and the recovery and treatment of sulfuric acid from the saccharification liquid and waste liquid, which places a high burden on the environment.
On the other hand, in the enzymatic saccharification method, the enzymatic reaction proceeds at a relatively low temperature of about 50°C and does not require a large amount of strong acid or strong alkaline chemicals, so there is an advantage in that the environmental impact is small, but there is a disadvantage in that a long reaction time is required compared to the above-mentioned acid saccharification method. In addition, there are a very large number of enzymes collectively called cellulase, and it is necessary to select and mix appropriate enzymes for the target cellulose and hemicellulose, which is currently expensive. Furthermore, the biggest problem with the enzymatic saccharification method is that the strong wood structure becomes an obstacle and the enzymatic reaction does not proceed as it is. In other words, there is a problem that cellulose and hemicellulose are covered with lignin, making it difficult for enzymes to physically reach cellulose and hemicellulose.

In recent years, cellulose fiber has been attracting attention as a material that has a small environmental impact in terms of production and disposal because it is derived from plants.
Although cellulose fiber is lightweight, it has excellent properties such as a high elastic modulus equivalent to that of aramid fiber, which is known as a high-strength fiber, and its expansion and contraction due to temperature changes is as small as that of glass fiber.
Known applications of cellulose fibers include using the fibers as heat insulating materials and dispersing them in resins as fillers. In particular, composite materials in which cellulose fibers are dispersed in biodegradable resins have the potential to expand the uses of biodegradable resins by achieving both biodegradability and strength, and are expected to contribute to solving the marine plastic problem. In addition, cellulose nanofibers prepared to the nano order are expected to be used in a variety of fields, including filter materials, high gas barrier packaging materials, electronic devices, food, medicine, cosmetics, and health care.
Cellulose fiber can be obtained by defibrating plant-derived fibers such as pulp, optionally in the presence of enzymes.
Depending on the application, cellulose fibers may contain components other than cellulose. In this case, cellulose can be separated by crushing plant biomass containing cellulose, and the cellulose can be defibrated by further crushing to obtain a composition containing cellulose fibers.

Here, wet grinding is an operation in which the raw material to be ground is dispersed in a liquid, i.e., in a slurry state, and the particles are easily ground because they are dispersed in water, etc., and the resulting particle size is finer than in dry grinding, so this method is used in the production of bioethanol and cellulose fiber, as mentioned above.
For example, Patent Document 1 discloses a method for obtaining cellulose fibers on the order of micrometers by micronizing plant fibers through wet grinding using a bead mill.
However, it is difficult to pulverize a high-viscosity slurry-like processed product in a bead mill, and the solid content concentration of the raw material cannot be increased, so the solid content concentration is processed at an order of 5 mass % or less. The slurry-like processed product prepared in this way contains a large amount of water, and therefore there is a problem that a huge amount of energy is consumed to remove the large amount of water in a subsequent process.

Wet grinding is classified into a batch type and a continuous type.
In the batch type, a large amount of material adheres to the container and components of the crushing device for each input, and since this cannot be recovered, the yield is poor, and generally about 20 to 30% of the solid content input is discarded. In addition, since the batch type can process a small amount at a time, multiple processings are required to process a large amount, and the number of processing times increases, and cleaning is unavoidable when switching between batches, resulting in even larger amounts of waste.
On the other hand, the continuous type usually means a one-pass system in which the material to be treated passes through once, and therefore cannot perform sufficient pulverization. Therefore, a circulation system in which the material discharged from the pulverization section is circulated and pulverized again has been considered. The advantage of the circulation system is that not only can fine pulverization be performed, but also that a large amount of material can be pulverized at once by expanding the circulation path by providing a tank or the like. Even if the processing capacity of the pulverization means is the same, by providing an external circulation path, a large amount of pulverized product can be obtained by the operator simply setting the material to be treated, starting the operation, and waiting for processing, so a significant improvement in work efficiency can be expected.

In the bead mill described above, a circulatory grinding process is performed with a circulation path equipped with a tank, as shown in Figure 8, for the purpose of efficient mass processing. However, as described above, when the viscosity of the slurry is high, the grinding efficiency of the beads in the bead mill decreases. In addition, a mechanism (such as a screen) is required to separate the beads, and when processing a high-viscosity slurry or when the flow rate of the slurry is high, the beads become biased, which is also a factor in reducing the grinding efficiency. Therefore, in the circulatory grinding process of the bead mill, it is necessary to further reduce the solid content concentration (for example, about 1 mass%), and the slurry-like processed product prepared in this way contains a large amount of water, so there is a problem that even greater energy is consumed to remove the water in the subsequent process.

As an example of a wet grinding device that does not use beads, Patent Document 2 discloses a grinding device in which a rotating main shaft is erected at the center of a container, a plurality of sub-shafts are circumferentially supported by the main shaft at intervals, and a plurality of ring-shaped members are fitted onto the sub-shafts with sufficient gaps between them, and the ring-shaped members are brought into contact with the inner wall of the container.
The pulverizing device disclosed in Patent Document 2 is described as being capable of processing not only in a batch manner (batch type) but also in a continuous manner (single pass type).

According to Patent Document 3, the same grinding device as that disclosed in Patent Document 2 is capable of mixing and grinding calcium phosphate slurry with a solid content concentration of 40% by weight. Since the grinding device disclosed in Patent Document 2 can grind a slurry-like material with a high solid content concentration and high viscosity, if this grinding device is used for circulating grinding, it is expected that a large amount of the material can be wet-ground without diluting it to reduce the solid content concentration. In particular, by applying this to wet grinding of wood materials and plant-derived fibers, it is expected that the above-mentioned bioethanol production and cellulose fiber production can be performed in a larger amount and more efficiently than before. According to the study by the present inventors, it was found that the grinding device of Patent Document 2 can grind a slurry-like material with a high solid content concentration of up to 15% by mass when used for wet grinding of wood materials and plant-derived fibers.

However, it has been found that even with the grinding device described in the above-mentioned Patent Document 2, when a circulatory grinding process having an external circulation path as shown in FIG. 8 is performed, the following problems occur.
When the circulation path is greatly expanded by providing an external tank or the like, a larger amount of material to be treated circulates through the circulation path as a whole system compared to the conventional batch type. For example, depending on the capacity of the external tank, the amount of material to be treated circulates may be more than ten times that of the batch type. In such a case, materials that flow easily are preferentially circulated through the entire circulation path, and it was found that even when using the crushing device described in Patent Document 2, the crushing process of the solid content (material to be treated) does not proceed as expected. It was found that this tendency is particularly noticeable in the crushing process of plant biomass materials that are easily separated from water, such as wood materials, and in the fiberization process of pulp.
The pulverizer of Patent Document 2 has a structure in which a slurry-like material is supplied from the bottom of the device, and inside the pulverizer, the slurry-like material is transported upward against gravity. This has the advantage that the pulverization process proceeds reliably even when starting from a high solid content concentration, but when a circulatory pulverization process is performed with a circulation path equipped with an external tank, differences in the circulation speed of water and solids occur at various points in the circulation path, especially just before the supply port of the pulverizer, and the introduction of the solids (processed material) that are difficult to flow into the pulverizer is delayed, which is presumably impeding the progress of the pulverization process of the solids (processed material).
In addition, in the circulating grinding process of plant biomass, the slurry-like processing material is initially a mixture of water and solids, but the viscosity increases as the grinding process progresses. In particular, when the solid concentration is high, such changes in properties and viscosity are significant, and if a transport means that is relatively compatible with the circulating process of the initial mixture of water and solids is selected, there is a problem that the viscosity increases over time, making it impossible to transport the slurry-like processing material, and it is difficult to build a simple system that can handle large-scale processing from the beginning to the end of time.

JP 2011-213754 A Japanese Patent Application Publication No. 06-79192 International Publication No. 2000-58210

The present invention has been made in consideration of the problems inherent in the background art described above, and its purpose is to provide a circulatory grinding processing device that has a circulation path and can stably perform circulatory grinding processing from the beginning to the end of time. In particular, the present invention provides a circulatory grinding processing device that can circulate and grind large amounts of plant biomass material, particularly wood material and plant-derived fibers, in the form of a slurry-like processing product with a high solid content concentration.

In order to achieve the above-mentioned object, the present invention provides a circulating grinding treatment device, a circulating grinding treatment method, a method for producing an alcohol, and a method for producing a composition containing cellulose, as described in the following [1] to [9].
[1] A crushing device in which a supply port for a slurry-like material to be treated is provided at the bottom of a container, a rotating main shaft is provided inside the container, a plurality of sub-shafts are supported at intervals around the main shaft, a plurality of ring-shaped members are fitted to the sub-shafts with gaps between them, the ring-shaped members are arranged to abut against the inner wall of the container, and a discharge port for the slurry-like material is provided at the top of the container;
an external circulation path portion for a slurry-like treated material connected to the discharge port of the pulverizing device;
a screw feeder that conveys the slurry-like treatment product discharged from the discharge port of the external circulation path section to the supply port of the grinding device,
the screw feeder is disposed between a discharge port of the external circulation path section and a supply port of the grinding device;
The slurry-like treatment product is circulated through the grinding device, the external circulation path section, and the screw feeder in this order to perform the grinding treatment.
Circulating grinding processing equipment.
[2] The circulation grinding processing apparatus according to [1], wherein the external circulation path section is provided with an external tank.
[3] The circulation grinding processing device according to [1] or [2], characterized in that the tip of the screw feeder extends further downstream than just below the supply port of the grinding device, and the screw blades of the screw feeder are formed in the feed direction up to just before the supply port of the grinding device, are not formed just below the supply port, and are formed in the return direction downstream of the supply port.
[4] The circulation grinding processing device according to any one of [1] to [3] above, characterized in that the screw feeder is formed into a twin screw.
[5] A circulatory grinding method, comprising circulating and grinding a slurry-like treated product of plant biomass using the circulatory grinding treatment device according to any one of [1] to [4] above.
[6] The circulation and grinding method according to [5] above, wherein the slurry-like treated product is a slurry of plant biomass having a solid content of 3 to 15 mass %.
[7] The circulation and crushing method according to [5] or [6] above, characterized in that the plant biomass is any one of woody, herbaceous, and cellulosic biomass.
[8] A method for producing alcohol, comprising: using the circulating grinding treatment device according to any one of [1] to [4] above, circulating and grinding a slurry-like treated product of plant biomass; and saccharifying and fermenting the resulting ground product.
[9] A method for producing a composition containing cellulose fiber, comprising circulating and pulverizing a slurry-like treated product of plant biomass using the circulating and pulverizing treatment device described in any one of [1] to [4] above.

The circulatory grinding processing device according to the present invention described above can perform a circulatory grinding process having a circulation path stably from the beginning to the end of time. In particular, it can perform a circulatory grinding process on a large amount of plant biomass, particularly woody materials and plant-derived fibers, in the form of a slurry-like processing material with a high solid content concentration.

1 is a front view showing one embodiment of a circulating crushing treatment device according to the present invention. FIG. 2 is a plan view of the circulating crushing treatment device shown in FIG. 1 . FIG. 2 is a side view of the circulating crushing treatment device shown in FIG. 1 . 1 is a vertical sectional view showing one embodiment of a crushing device used in a circulating crushing treatment device according to the present invention. FIG. 5 is a cross-sectional view of the grinding device shown in FIG. 4 . 1 is a front view showing a main part of an embodiment of a screw feeder used in a circulating crushing treatment device according to the present invention. FIG. FIG. 7 is a plan view showing a screw shaft of the screw feeder shown in FIG. 6 . FIG. 1 is a front view conceptually showing a conventional example of a circulatory grinding treatment device using a bead mill.

Below, one embodiment of the circulating grinding processing device according to the present invention will be described in detail with reference to the drawings.

As shown in Figures 1 to 3, the circulating grinding processing device 1 according to the present invention is composed of a grinding device 100, an external circulation path section 200, and a screw feeder 300.

As shown in detail in Figures 4 and 5, the grinding device 100 has a cylindrical container 101, a rotation mechanism 102 installed in the container 101, a supply port 103 for the slurry-like treated material formed at the bottom of the container, and a discharge port 104 for the slurry-like treated material formed at the top of the container.

The container 101 has an inner circumferential surface 105 with a central axis in the vertical direction, and the above-mentioned rotation mechanism 102 is installed inside the container 101, which serves as a processing chamber. This rotation mechanism 102 is composed of a main shaft 106 that shares the same central axis as the container 101, a pair of upper and lower pressure plates 107, 108 fixed at a fixed interval in the longitudinal direction of the main shaft 106, and a sub-shaft 109 fixed between the pressure plates 107, 108 so as to be parallel to and equidistant from the main shaft 106.

The pressure plates 107, 108 have the same number of arms protruding radially as the number of sub-shafts 109. By making the pressure plates 107, 108 not simply disk-shaped, but with gaps between each arm, the degree of convection (mixing) of the slurry-like processing material put into the container 101 is improved, and the amount of processing material that accumulates as dead stock on the upper pressure plate 107 can be reduced as much as possible.

The sub-shaft 109 is a long bolt-like member, and each end is inserted into a through hole provided at the tip of the arm-shaped portion of both pressure plates 107, 108 and fastened with a nut 110. The upper end of the main shaft 106 is directly connected to a driving source such as a motor (not shown), or is configured to transmit the rotational force of the driving source to the main shaft 106 via a pulley and a V-belt.

In order to increase the wear resistance of the constituent materials, as shown in the illustrated embodiment, a cylindrical collar 111 is fitted to each sub-shaft 109 with a small gap. Furthermore, a plurality of ring-shaped members 112 are rotatably attached to each sub-shaft 109 via the fitted collar 111 as grinding media. The inner diameter of each ring-shaped member 112 is sufficiently larger than the outer diameter of the collar 111, and the ring-shaped member 112 is structured so that there is a sufficient gap between the inner peripheral surface of the ring-shaped member 112 and the outer peripheral surface of the collar 111 when its outer peripheral surface abuts against the inner peripheral surface 105 of the container 101. Furthermore, the ring-shaped members 112 are not densely stacked without gaps between the two pressure plates 107 and 108, but are stacked so as to form a gap of a thickness equivalent to 2 to 3 ring-shaped members 112 between the upper end surface of the stack of the ring-shaped members 112 and the lower surface of the pressure plate 107. This layered structure allows each ring-shaped member 112 to freely rotate around the collar 111.

The ring-shaped member 112 is formed in a cylindrical shape with parallel upper and lower surfaces, and is formed in a so-called washer shape with smooth upper and lower surfaces and outer peripheral surface. If necessary, the outer peripheral surface may be formed in a curved shape to promote biting into the material to be processed. The size of this ring-shaped member 112 as a grinding medium varies depending on the type (size) of the processing device, but has an outer diameter of 25 to 45 mm and a thickness of about several mm. Also, its material varies depending on the physical properties of the material to be processed, but is made of stainless steel, ceramic materials such as alumina and zirconia, superhard materials such as WC, etc.

The main shaft 106, located below the lower pressure plate 108 and above the upper pressure plate 107, is provided with stirring blades 113, 114, as necessary, for stirring the slurry-like material to be treated that has been introduced into the container 101, as shown in the illustrated embodiment.
In order to prevent the temperature of the slurry-like treatment material from rising when the grinding process is carried out, the side of the container 101 is covered with a jacket 115, which is provided with a refrigerant supply port 116 and a discharge port 117. Various refrigerants can be continuously supplied into the jacket 115, so that the slurry-like treatment material placed in the container 101 can be cooled.

In the crushing device 100 having the above-mentioned configuration, a gap is formed between the outer diameter of the sub-shaft 109 (the outer diameter of the cylindrical collar 111) and the inner diameter of the ring-shaped member 112 fitted to the sub-shaft 109 (the cylindrical collar 111), and the ring-shaped member 112 is configured to be able to rotate freely and independently. The ring-shaped member 112, which acts as a crushing medium, moves in the radial direction by an amount equivalent to the gap due to the centrifugal force generated with the rotation of the main shaft 106, and revolves inside the container 101 while being pressed against the container inner surface 105. In addition, the ring-shaped member 112 itself rotates around the sub-shaft 109 due to friction with the inner surface 105, etc. In other words, the ring-shaped member 112 becomes a complex object that moves inside the container 101 while repeatedly revolving and rotating. Therefore, when the slurry-like treated material is continuously supplied from the supply port 103 provided at the bottom of the container 101, the slurry-like treated material supplied into the container 101 is pushed upward from below and receives the compressive and shearing forces of the ring-shaped member 112 that rotates in a complex manner, so that it is efficiently pulverized and continuously discharged from the discharge port 104 provided at the top of the container 101.

As shown in FIG. 1, an external circulation path section 200 is connected to the discharge port 104 of the grinding device 100. This external circulation path section 200 acts as a path for circulating the slurry-like processing material outside the grinding device 100, and also acts to increase the processing volume. Therefore, it is preferable that the external circulation path section 200 has a certain degree of volume. In the embodiment shown in FIGS. 1 to 3, the external circulation path section 200 is provided with an external tank 201 from the viewpoint of increasing the processing volume, etc.

The external tank 201 has an internal space 202 for temporarily storing the slurry-like treated product, a supply port 203 for supplying the slurry-like treated product to the internal space 202, and a discharge port 204 for discharging the slurry-like treated product to the outside of the internal space 202. In the illustrated embodiment, the internal space 202 is formed in a cylindrical shape having an elliptical cross section extending along the vertical direction, the supply port 203 is formed in a cover plate that closes the upper end, and the lower open end serves as the discharge port 204.

The supply port 203 of the external tank 201 is connected to the open end of a pipe 205 connected to the discharge port 104 of the grinding device 100, and the slurry-like processed material ground by the grinding device 100 is supplied to the internal space 202 of the external tank 201 through the pipe 205, temporarily stored therein, and then discharged from the discharge port 204, which is the lower open end. The volume of the external tank 201 varies depending on the physical properties of the slurry-like processed material, but is determined based on a balance between the processing volume and grinding efficiency, and in the circulating grinding processing device 1 according to the illustrated embodiment, the volume of the external tank 201 is designed to be preferably 5 times or more, more preferably 10 times or more, the volume of the grinding device 100 (volume excluding the rotation mechanism).

The slurry-like treated material discharged from the discharge port 204 of the external circulation path section 200 is transported to the supply port 103 of the pulverizer 100 by the screw feeder 300. As shown in FIG. 1, the screw of the screw feeder 300 is arranged from the discharge port 204 of the external circulation path section 200 to the supply port 103 of the pulverizer 100, and the slurry-like treated material is forcibly transported from the external circulation path section 200 to the pulverizer 100 by the rotation of the screw.

As shown in Figures 1 to 3, the screw feeder 300 is formed as a twin screw having a pair of screw shafts 301, 302 arranged in parallel along the horizontal direction, and is equipped with bearings 303, 304 that rotatably support the pair of screw shafts 301, 302, a casing 305 that extends along the horizontal direction and houses the pair of screw shafts 301, 302, and a drive mechanism 306 that rotates the pair of screw shafts 301, 302.

As shown in FIG. 7, each of the pair of screw shafts 301, 302 includes shafts 307, 308 that extend along the axis LA (LA1, LA2) and are rotatable, and screw blades 309, 310 that are spirally provided on the outer periphery of the shafts 307, 308. As shown in FIG. 6, the casing 305 that houses the pair of screw shafts 301, 302 has openings 311, 312 formed at positions corresponding to the discharge port 204 of the external circulation path section 200 and at positions corresponding to the supply port 103 of the crushing device 100. As shown in FIG. 1, the drive mechanism 306 rotates the shafts 307, 308 of the pair of screw shafts 301, 302 inwardly relative to each other when viewed from above, as shown by arrows in FIG. 3 and FIG. 7, by means of a motor 313 and a gear train 314 that transmits the rotation of the motor 313.

As shown in Figures 6 and 7, at least one of the pair of screw shafts 301, 302, the tip of which extends further downstream than directly below the supply port 103 of the crushing device 100, and the screw blades 310 of the screw shaft 302 are formed in the feed direction up to just before the supply port 103 of the crushing device 100, are not formed directly below the supply port 103, and are formed in the return direction downstream of the supply port 103.

The pair of screw shafts 301, 302 have a cantilever structure supported by bearings 303, 304 on the drive mechanism 306 side, respectively, and it is necessary to prevent the screw blades 309, 310 on the tip side of the screw shafts from hitting the casing 305 that surrounds them even when a force is applied in a direction perpendicular to the rotation axis. To achieve this, a bearing may be provided to support the tips of the screw shafts 301, 302, but in the screw feeder 300, the clearance between them is narrowed so that the tips of the screw shafts 301, 302 hit a bracket or the like provided on the casing before the screw blades 309, 310 hit the casing 305.
Since providing such a structure directly below the supply port 103 is not preferable for transporting the slurry-like treated material, the tip of the screw is positioned further extended than the supply port 103 of the grinding device 100, and no screw blade 310 is formed directly below the supply port 103, while the screw blade 310 is formed in the return direction downstream of the supply port 103. Therefore, the slurry-like treated material heading toward the tip of the screw is pushed back by the screw blade 310 formed in the return direction, and the slurry-like treated material is effectively pushed toward the supply port 103 of the grinding device 100, preventing the slurry-like treated material from stagnation.

As shown in FIG. 6, by using the screw feeder 300 with the above configuration, the slurry-like processed material discharged from the discharge port 204 of the external circulation path section 200 is supplied to the internal space of the feeder from the upstream opening 311 in the transfer direction A formed in the casing 305, and is captured in the gap between the pitches of the rotating screw blades 309, 310 and transported downstream. The slurry-like processed material transported downstream in the transfer direction A is discharged to the outside from the downstream opening 312 formed in the casing 305, and is forced into the grinding device 100 from the supply port 103 of the grinding device 100.

The conveying capacity of the screw feeder 300 varies depending on the processing capacity of the grinding device 100 and the physical properties of the slurry-like material being conveyed, but is determined by balancing the processing volume and grinding efficiency. In the illustrated embodiment of the circulating grinding processing device 1, the conveying capacity of the screw feeder 300 is designed to be preferably 50 to 1000 ml/min, and more preferably 100 to 1000 ml/min, in terms of the volume of slurry-like material conveyed per hour, by adjusting the size and pitch of the screw blades 309, 310 and the shaft rotation speed.

The circulating grinding processing device 1 according to the present invention described above is a grinding device 100, which includes a container 101 having a supply port 103 for a slurry-like material to be processed at the bottom thereof, a rotating main shaft 106 standing upright inside the container 101, a plurality of sub-shafts 109 supported at intervals around the main shaft 106, a plurality of ring-shaped members 112 fitted on the sub-shafts 109 with gaps between them, the ring-shaped members 112 being disposed so as to abut against an inner wall 105 of the container, and the container 10 Since a discharge outlet 104 for the slurry-like treated material is provided at the top of vessel 101, the slurry-like treated material continuously supplied from supply port 103 provided at the bottom of vessel 101 is efficiently pulverized by the compressive and shearing forces of ring-shaped member 112 which is pushed up from below within vessel 101 and rotates in a complex manner while rising, and is continuously discharged from discharge outlet 104 provided at the top of vessel 101, so that even a slurry-like treated material with a high solid content and high viscosity can be efficiently pulverized.
In addition, the circulating grinding processing device 1 according to the present invention has an external circulation path section 200 for a slurry-like processed material connected to the discharge port 104 of the grinding device 100, and a screw feeder 300 for transporting the slurry-like processed material discharged from the discharge port 204 of the external circulation path section 200 to the supply port 103 of the grinding device 100, and the screw feeder 300 is arranged from the discharge port 204 of the external circulation path section 200 to the supply port 103 of the grinding device 100, and the slurry-like processed material is circulated in the order of the grinding device 100, the external circulation path section 200, and the screw feeder 300 to perform the grinding process. Therefore, the slurry-like processed material is circulated without separation of the solid content (processed material) from the dispersion medium such as water, which is a concern in a device having a pump conveying configuration, and the grinding process of the solid content (processed material) proceeds reliably.
Furthermore, by means of the stirring blades 113 and 114 for stirring the slurry-like material fed into the vessel 101, no dead space is created within the vessel 101, and the slurry-like material is circulated.

As a result, the circulatory grinding processing device 1 according to the present invention can stably perform circulatory grinding processing of a slurry-like processing material having a circulation path from the beginning to the end of time.

The circulating grinding processing device 1 according to the present invention described above is suitable for circulating and grinding high-concentration slurry-like processing materials, and the proportion of the solid content (processed product) of the slurry-like processing material varies depending on the particle size, true density, shape, and other physical properties of the solid content (processed product), but in the case of plant biomass, it is preferably in the range of 3 to 15% by mass, and more preferably in the range of 5 to 12% by mass. This is because a concentration of less than 3% by mass does not lead to an improvement in processing efficiency compared to the conventional technology, and a concentration of more than 15% by mass for plant biomass results in too high a viscosity.
Moreover, examples of materials to be circulated and pulverized using the circulating and pulverizing processing device 1 according to the present invention include materials that are easily separated from the dispersion medium such as water, for example, plant biomass. Here, examples of plant biomass include woody, herbaceous, and cellulose-based materials, and examples of woody and herbaceous materials include plant materials such as wood, bamboo, hemp, herbaceous plants, agricultural products, waste materials, and residues (skin, leaves, stems, fruits) of the plant materials. Examples of cellulose-based materials include wood pulp, non-wood pulp made from straw, bagasse, cotton, hemp, bast fiber, etc., and waste paper pulp (DIP) made from recycled waste paper, broke paper, etc.
Woody, herbaceous, and cellulosic biomass all have in common the fact that they contain cellulose.

For the reasons described above, the circulating grinding processing device 1 according to the present invention can be suitably used as a circulating grinding processing method using the circulating grinding processing device 1 to circulate and grind a slurry-like treated product of plant biomass, as a method for producing alcohol using the circulating grinding processing device 1 to circulate and grind a slurry-like treated product of plant biomass and saccharify and ferment the resulting ground product, and as a method for producing a composition containing cellulose fiber using the circulating grinding processing device 1 to circulate and grind a slurry-like treated product of plant biomass.

1. Grinding of wood materials [Example 1]
(1) Treated material The treated material was cedar sawdust from the Kanto region, which is commercially available for gardening and pet use. The median particle size of this cedar sawdust was 0.5 to 1.0 mm when measured by sieving. Many of the sawdust had a large needle-like aspect ratio, with some measuring up to 2 to 3 mm in length.
(2) Preparation of Treated Products Water was added to the powder of the above-mentioned wood material to prepare two types of slurry-like treated products having solid concentrations of 10% by mass and 15% by mass.
(3) Crushing using a crushing device

Example 1-1
The slurry-like material to be treated, having a solid content concentration of 10% by mass, was subjected to a circulating pulverizing treatment using the circulating pulverizing treatment apparatus 1 according to the embodiment of the present invention shown in FIGS.
As the pulverizing device 100, a Micros 0 type (MIC-0, volume excluding the rotation mechanism is 0.4 liters) manufactured by Nara Machinery Manufacturing Co., Ltd. was used, the external tank 201 had a volume of 0.3 liters, and the diameter including the screw blade of the screw feeder 300 was 14 mm. Pulverization was performed under the following processing conditions.
(Processing conditions)
・Amount of slurry-like material to be treated: 0.500 kg
Total solids (processed material) 0.050 kg
・Crushing device rotation speed: 1500 rpm
・Screw feeder rotation speed: 50 rpm
Screw feeder conveying capacity: 100 ml/min

Example 1-2
The slurry-like material to be treated, having a solid content concentration of 10% by mass, was subjected to a circulating pulverizing treatment using the circulating pulverizing treatment apparatus 1 according to the embodiment of the present invention shown in FIGS.
However, the external tank 201 was changed to one with a volume of 3 liters, and the rest of the apparatus was the same as that in the above-mentioned [Example 1-1], and pulverization was carried out under the following processing conditions.
(Processing conditions)
・Amount of slurry-like treated material: 2.500 kg
Total solids (processed material) 0.250 kg
・Crushing device rotation speed: 1500 rpm
・Screw feeder rotation speed: 50 rpm
Screw feeder conveying capacity: 100 ml/min

[Examples 1 to 3]
The other slurry-like material having a solid content concentration of 15% by mass was subjected to a circulating pulverizing treatment using the circulating pulverizing treatment apparatus 1 according to the embodiment of the present invention shown in FIGS.
As the pulverizing device 100, a Micros 0 type (MIC-0, volume excluding the rotating mechanism is 0.4 liters) manufactured by Nara Machinery Manufacturing Co., Ltd. was used, the external tank 201 was 3 liters, and the diameter of the screw feeder 300 including the screw blade was 14 mm. The same device as in the above [Example 1-2] was used, and pulverization was performed under the following processing conditions.
(Processing conditions)
・Amount of slurry-like treated material: 2.500 kg
Total solids (processed material) 0.375 kg
・Crushing device rotation speed: 1500 rpm
・Screw feeder rotation speed: 50 rpm
Screw feeder conveying capacity: 100 ml/min

[Examples 1 to 4]
The slurry-like material to be treated, having a solid content concentration of 10% by mass, was subjected to a circulating pulverizing treatment using the circulating pulverizing treatment apparatus 1 according to the embodiment of the present invention shown in FIGS.
As the pulverizing device 100, a Micros 3 type (MIC-3, volume excluding the rotating mechanism is 3.0 liters) manufactured by Nara Machinery Manufacturing Co., Ltd. was used, the external tank 201 was 24 liters, and the diameter including the screw blade of the screw feeder 300 was 28 mm. Pulverization was performed under the following processing conditions.
(Processing conditions)
・Amount of slurry-like treated material charged: 40.0 kg
Total amount of solids (processed material) 4.00 kg
・ Rotation speed of the grinding device: 1100 rpm
・Screw feeder rotation speed: 50 rpm
・Screw feeder conveying capacity: 800 ml/min

Comparative Example 1-1
Except for changing the screw feeder in the above [Example 1-1] to a pump (Mono Pump CY type, manufactured by Heishin Soubi Co., Ltd.), the same equipment as in the above [Example 1-1] was used, and the slurry-like treated product having a solid content concentration of 10 mass % was subjected to a circulation grinding process under the same processing conditions as in the above [Example 1-1].

Comparative Example 1-2
The grinding device of the above [Example 1-1] was replaced with a bead mill (vessel volume 1.0 liter, bead filling amount 608 ml (2300 g)) and the screw feeder was replaced with a pump (manufactured by Heishin Soubi Co., Ltd., Mono Pump CY type). The same equipment as in the above [Example 1-1] was used, and the slurry-like treated product with a solid content concentration of 10% by mass was first subjected to a circulation grinding treatment under the same treatment conditions as in the above [Example 1-1]. However, when the slurry-like treated product with a solid content concentration of 10% by mass was added and the rotation speed of the bead mill was gradually increased, an abnormal noise was heard in the bead mill at 120 rpm, so the test was stopped. Therefore, the solid content concentration of the slurry-like treated product was reduced to 1% by mass, and the bead mill was rotated at a speed of 20,000 rpm.
The total amount of solids (processed material) at this time was 0.005 kg.

Comparative Examples 1-3
Using only the grinding apparatus 100 shown in Figs. 4 and 5, the slurry-like material to be treated, which had a solid content of 10% by mass, was subjected to a batch-type grinding process.
The crushing device 100 used was a Micros 0 type (MIC-0, volume excluding the rotating mechanism is 0.4 liters) manufactured by Nara Machinery Manufacturing Co., Ltd., and crushing was performed under the following processing conditions.
(Processing conditions)
・Amount of slurry-like material to be treated: 0.250 kg
Total solids (processed material) 0.025 kg
・Crushing device rotation speed: 1500 rpm

Comparative Examples 1-4
Using only the grinding apparatus 100 shown in Figs. 4 and 5, the slurry-like material to be treated having a solid content of 10% by mass was subjected to a batch-type grinding process twice.
The crushing device 100 used was the Micros 0 type (MIC-0, volume excluding the rotating mechanism is 0.4 liters) manufactured by Nara Machinery Manufacturing Co., Ltd., similar to that used in Comparative Example 1-3, and crushing was performed under the following processing conditions.
(Processing conditions)
・Amount of slurry-like material to be treated: 0.250 kg
Solid content (processed material) amount: 0.025 kg
・Crushing device rotation speed: 1500 rpm
Two batches were processed under the above conditions. Total solids (processed material) amount: 0.050 kg

Comparative Examples 1 to 5
Using only the grinding apparatus 100 shown in Figs. 4 and 5, the slurry-like material to be treated having a solid content concentration of 10% by mass was subjected to 10 batch-type grinding processes.
The crushing device 100 used was the Micros 0 type (MIC-0, volume excluding the rotating mechanism is 0.4 liters) manufactured by Nara Machinery Manufacturing Co., Ltd., similar to that used in Comparative Example 1-3, and crushing was performed under the following processing conditions.
(Processing conditions)
・Amount of slurry-like material to be treated: 0.250 kg
Total solids (processed material) 0.025 kg
・Crushing device rotation speed: 1500 rpm
10 batches were processed under the above conditions. Total solids (processed material) amount: 0.250 kg

For the above [Example 1-1] to [Example 1-4] and [Comparative Example 1-1] to [Comparative Example 1-5], the yield, the time until the processed material reaches a median diameter (d50) of 7 μm ± 0.3 μm (total grinding time), the equipment production capacity calculated by dividing the yield by the total operating time, etc. are shown in Table 1.

As shown in Table 1, in [Example 1-1], where a screw feeder was used as the conveying means, the total grinding time was reduced by 40% or less compared to [Comparative Example 1-1], where a mono pump was used. The equipment production capacity calculated by dividing the yield by the total operation time was 0.0129 and 0.0062 in [Example 1-1] and [Comparative Example 1-1], respectively, which was improved by 2.1 times.
In [Comparative Example 1-2] in which a bead mill was used, the solid concentration was reduced to 1 mass %, and therefore the production capacity of the equipment obtained by dividing the yield by the total operation time was "0.0009."
In [Example 1-1], the equipment production capacity obtained by dividing the yield by the total operation time was "0.0129", which was improved by 1.35 times and 1.2 times, respectively, compared to "0.0095" in [Comparative Example 1-3], which was a conventional batch process, and "0.0108" in [Comparative Example 1-4], which processed the same feed amount using a batch process.
As shown in Table 1, in Example 1-2, in which the throughput was increased tenfold by using an external circulation route, there was little switching loss and the yield was 96%, whereas in Comparative Example 1-5, which had the same throughput, the yield was 80%.
In [Example 1-2], the equipment production capacity calculated by dividing the yield by the total operation time was 0.0197, which was 1.6 times higher than the 0.0121 in [Comparative Example 1-5] in which the same amount of material was processed in a batch manner.
As can be seen from the comparison of [Example 1-1], [Example 1-2], and [Comparative Example 1-3] to [Comparative Example 1-5], the equipment production capacity is improved in the Examples compared to the Comparative Example in which the same feed amount was processed in a batch manner, and the degree of improvement is greater as the feed amount using the external circulation route is larger.
In [Example 1-3], even when the solid content was increased to 15%, the production capacity of the apparatus was equivalent to that of [Example 1-2].
In [Example 1-1] to [Example 1-4], continuous operation processing for a long period of time was possible, and the operator's response time was only one hour for cleaning before and after, excluding the measurement of particle size.
In [Example 1-2], the raw materials were set and the circulation treatment device was started, and the treatment was completed in a total operation time of about 12 hours. The operator was freed from the work except for the measurement of particle size just before the end, and was able to do other work.
In the case of the batch processing of the same amount of feed [Comparative Example 1-5], the total work time was more than 16 hours, and the work had to be divided into two days. During this time, the operator switched the batches for 30 minutes about every hour.
In addition, when the treatment device was changed to one with a volume of 3.0 liters excluding the rotation mechanism [Example 1-4], 40 kg of slurry-like treatment material (4 kg of wood material) with a solid content concentration of 10% by mass could be treated in a total working time of 21 hours.

2. Ethanol production [Example 2]
Except for using the slurry-like treated material that had been subjected to the alkali treatment described below as the treated material, circulation treatment was carried out in the same manner as in the above [Example 1-1] to [Example 1-4] and [Comparative Example 1-3] to obtain wood slurries of [Example 2-1] to [Example 2-4] and [Comparative Example 2-3], respectively.
[Alkaline treatment]
A slurry of wood material with a solids concentration of 10% by mass was placed in a commercially available pressure cooker, followed by adding alkaline water to adjust the pH to 2, and then performing an immersion treatment at 120°C for 4 hours while pressurizing and heating without stirring.
[Circulation grinding process]
The circulation treatment was carried out in the same manner as in [Example 1-1] to [Example 1-4] and [Comparative Example 1-3].
[Saccharification and fermentation conditions]
For the wood slurries obtained in [Example 2-1] to [Example 2-4], 50 g of each collected wood slurry was diluted with 90 ml of distilled water and transferred to a baffled Erlenmeyer flask, after which a suspension of Novozymes enzymes (1.3 ml of Ctec2 and 400 μl of Htec2) in 7.70 ml of distilled water was added, the flask was covered with aluminum foil, and the mixture was shaken in a shaking thermostatic bath at 50°C for 48 hours to perform saccharification treatment.
The obtained saccharified solution was adjusted to pH 6.5, sterilized using a sterile filter with a 0.45 μl pore size, and placed in a 1-liter measuring cylinder. Pre-cultured yeast SS4-5 was inoculated at a concentration of 1.0 × 107 cells/ml, and fermentation was carried out at 30°C for 3 days.
The yeast SS4-5 is a Schizosaccharomyces japonicus SS4-5 strain, and its accession number is NITE P-1197.

The concentration of Glc produced and the amount of alcohol obtained were measured for each of the above-mentioned saccharification and fermentation treatments (Example 2-1) to (Example 2-4). The measurement results are shown in Table 2.
In addition, in [Comparative Example 2-3], the above-mentioned alkali-treated wood slurry was used as the treated material, and the pulverization treatment was carried out in the same manner as in [Comparative Example 1-3]. The Glc production concentration and the amount of alcohol obtained after the above-mentioned saccharification and fermentation treatment were measured. The measurement results are shown in Table 2.
As shown in Table 2, a larger amount of alcohol could be produced in one treatment than in the conventional method.

3. Cellulose fiber production [Example 3]
Commercially available bleached softwood kraft pulp (N-BKP, manufactured by Oji Paper Co., Ltd., solids concentration 25% by mass) was diluted with water to prepare a slurry-like treated product with a solids concentration of 10% by mass.
The adjusted slurry-like treated material was subjected to a circulatory defibration process using the circulatory crushing process device 1 according to the embodiment of the present invention shown in Figures 1 to 7 (the crushing device 100 is manufactured by Nara Machinery Works, Ltd., Micros 0 type (MIC-0, volume excluding the rotation mechanism is 0.4 liters), the volume of the external tank 201 is 3 liters, and the diameter including the screw blade of the screw feeder 300 is 14 mm) under the following processing conditions.
(Processing conditions)
・Amount of slurry-like treated material: 5.0 kg (solid content: 0.5 kg)
・Crushing device rotation speed: 1800 rpm
・Screw feeder rotation speed: 45 rpm
Screw feeder conveying capacity: 80 ml/min

When the above-mentioned defibration treatment was carried out, the pulp did not separate and could be recycled.
After 10 minutes of treatment, the slurry-like treated product was washed three times with butanol and dried in a freeze-dryer, and the specific surface area was measured by nitrogen gas adsorption. The specific surface area was 92 ^m2 /g. After 30 minutes of treatment, the slurry-like treated product was washed three times with butanol and dried in a freeze-dryer, and the specific surface area was measured and found to be 132 ^m2 /g.
As described above, it was confirmed that the defibration of the cellulose contained in the pulp was progressing.

The circulating grinding and processing device of the present invention can be suitably used as a device for grinding plant biomass and producing ethanol, or as a device for defibrating pulp and producing cellulose fiber.

1: Circulation crushing processing device 100: Crushing device 101: Container, 102: Rotation mechanism, 103: Supply port, 104: Discharge port, 105: Inner surface, 106: Main shaft, 107: Pressing plate, 108: Pressing plate, 109: Sub-shaft, 110: Nut, 111: Collar, 112: Ring-shaped member, 113: Stirring blade, 114: Stirring blade, 115: Jacket, 116: Supply port, 117: Discharge port 200: External circulation path part 201: External tank, 202: Internal space, 203: Supply port, 204: Discharge port, 205: Piping 300: Screw feeder Reference Signs List 301: screw shaft, 302: screw shaft, 303: bearing, 304: bearing, 305: casing, 306: drive mechanism, 307: shaft, 308: shaft, 309: screw blade, 310: screw blade, 311: opening, 312: opening, 3013: motor, 314: gear train

Claims (9)

a crushing device having a supply port for a slurry-like material to be treated provided at a lower portion of a container, a rotating main shaft provided upright inside the container, a plurality of sub-shafts circumferentially supported by the main shaft at intervals, a plurality of ring-shaped members fitted on the sub-shafts with gaps provided between the sub-shafts, the ring-shaped members being disposed so as to abut against an inner wall of the container, and a discharge port for the slurry-like material provided at an upper portion of the container;
an external circulation path portion for a slurry-like treated material connected to the discharge port of the pulverizing device;
a screw feeder that conveys the slurry-like treated product discharged from the discharge port of the external circulation path section to the supply port of the grinding device,
the screw feeder is disposed between a discharge port of the external circulation path section and a supply port of the grinding device,
The slurry-like treatment product is circulated through the grinding device, the external circulation path section, and the screw feeder in this order to perform the grinding treatment.
Circulating grinding processing equipment. The circulating grinding processing device according to claim 1, characterized in that the external circulation path section is equipped with an external tank. The circulating grinding processing device according to claim 1 or 2, characterized in that the tip of the screw feeder extends further downstream than just below the supply port of the grinding device, and the screw blades of the screw feeder are formed in the feed direction up to just before the supply port of the grinding device, are not formed just below the supply port, and are formed in the return direction downstream of the supply port. The circulating grinding processing device according to any one of claims 1 to 3, characterized in that the screw feeder is formed as a twin screw. A circulatory grinding method, comprising circulating and grinding a slurry-like treated product of plant biomass using the circulatory grinding treatment device according to any one of claims 1 to 4. The circulation and grinding method according to claim 5, characterized in that the slurry-like treated material is a slurry of plant biomass with a solids concentration of 3 to 15 mass %. The circulatory grinding method according to claim 5 or 6, characterized in that the plant biomass is any one of woody, herbaceous, and cellulosic biomass. A method for producing alcohol, comprising: using the circulating grinding processing device according to any one of claims 1 to 4 to circulate and grind a slurry-like processed product of plant biomass; and saccharifying and fermenting the resulting ground product. A method for producing a composition containing cellulose fiber, comprising circulating and pulverizing a slurry-like treated product of plant biomass using the circulating and pulverizing treatment device according to any one of claims 1 to 4.

Images