Method for producing woody biomass-derived product, and woody biomass-derived product

Abstract

The present disclosure addresses the problem of providing a woody biomass-derived product production method in which a woody biomass pulverized material capable of removing insoluble inorganic components from woody biomass and reducing ash content is obtained, and a high-quality woody biomass-derived product is produced from the woody biomass pulverized material. This woody biomass pulverized material production method includes a processing step and a production step. The processing step includes a sieving step. In the sieving step, the woody biomass pulverized material is screened using a screen having a mesh size of 400 μm or more, thereby separating an oversize fraction retained on the screen from an undersize fraction passing through the screen, and the oversize fraction is recovered. In the production step, the woody biomass-derived product is produced from at least one of the oversize fraction and a compressed woody biomass obtained by compressing the oversize fraction.

Description

Method for manufacturing woody biomass-derived products, and woody biomass-derived products

[0001] This disclosure relates to a method for producing woody biomass-derived products and woody biomass-derived products.

[0002] Patent Document 1 describes a method for processing palm trunks. This method for processing palm trunks includes a grinding step of defibrating and grinding the palm trunks into parenchyma and vascular bundles using a grinder, a hydration step of adding water to the palm trunks ground in the grinding step to a range below their saturation moisture content, and a pressing step of pressing the powdered palm trunks that have been hydrated in the hydration step.

[0003] However, while the processing method described in Patent Document 1 can remove water-soluble inorganic components such as potassium, it cannot remove insoluble inorganic components such as silica, and therefore cannot sufficiently reduce the ash content of woody biomass. Woody biomass-derived products produced from such woody biomass have problems such as reduced quality, combustion problems, and deterioration of properties.

[0004] Japanese Patent Publication No. 2018-103074

[0005] The purpose of this disclosure is to provide woody biomass pulverized material that can remove insoluble inorganic components from woody biomass and reduce the ash content, a method for producing a woody biomass-derived product of good quality manufactured from the woody biomass pulverized material, and a woody biomass-derived product with a sufficiently reduced ash content.

[0006] A method for producing a woody biomass-derived product according to one aspect of the present disclosure comprises a processing step and a manufacturing step. The processing step includes a sieving step. The sieving step involves passing the woody biomass pulverized material through a screen with an opening of 400 μm or more, separating it into sieved material remaining on the screen and unsieved material that has passed through the screen, and recovering the sieved material. The manufacturing step produces a woody biomass-derived product from at least one of the sieved material and compressed woody biomass obtained by compressing the sieved material.

[0007] A woody biomass-derived product according to one aspect of this disclosure contains woody biomass pulverized material that does not contain ash particles with a mesh size equivalent to 400 μm or less. The ash content relative to the total amount of woody biomass pulverized material is 2% by mass or less.

[0008] A woody biomass-derived product according to one aspect of this disclosure contains compressed woody biomass, which is obtained by compressing woody biomass pulverized material that does not contain ash with a mesh size equivalent to 400 μm or less on a screen. The ash content relative to the total amount of compressed woody biomass is 2% by mass or less.

[0009] (1) Overview Woody biomass is biomass consisting of woody materials. Biomass refers to renewable, biologically derived organic resources (excluding fossil fuels). Plants used for woody materials are broadly classified into woody plants (so-called trees) and herbaceous plants (so-called grasses), but either woody or herbaceous plants are acceptable.

[0010] Woody biomass can be used as a raw material for woody biomass-derived products such as wood-based boards, fuel pellets, and paper pulp. Specifically, woody biomass pulverized by crushing woody biomass and woody biomass compressed by compressing this woody biomass pulverized material can be used to obtain fuel pellets or manufacture wood-based boards.

[0011] Examples of woody biomass include palm trees, hemp, bamboo, and grasses. Examples of palm trees include oil palm, fan palm, coconut palm, date palm, sago palm, acai, and palm fern. Examples of hemp include kenaf and jute. Examples of grasses include sugarcane (bagasse).

[0012] The oil palm, in particular, is a type of palm tree planted in Malaysia, Indonesia, and other countries for the purpose of obtaining edible oils. Palm oil and palm kernel oil are obtained from the fruit of the oil palm and are used for cooking oils and other purposes. On the other hand, parts of the oil palm other than the fruit are treated as underutilized resources. These underutilized parts of the oil palm include the trunk (OPT: Oil Palm Trunk), empty fruit bunches (EFB: Empty Fruit Bunch), leaves (OPF: Oil Palm Fronds), and stems. These parts of the oil palm contain sugar and are prone to decay, so they are currently left to decompose and disposed of as waste. However, greenhouse gases are released during decomposition, raising concerns about environmental problems. From the above perspective, the utilization of oil palm can contribute to the resource recovery of underutilized resources and the resolution of environmental problems.

[0013] When using palm trees, including oil palms, and their waste as woody biomass, it is necessary to remove as much inorganic components such as ash and sugars as possible beforehand. Inorganic components may degrade the quality of woody biomass-derived products. Specifically, they may cause problems with combustion equipment for fuel pellets, or reduce the durability, adhesiveness, and processability of wood-based boards.

[0014] Patent Document 1 presents a method for removing potassium contained in palm trunks, a biomass raw material, by dissolving it in water. However, this method cannot remove water-insoluble inorganic components such as silica, and therefore cannot sufficiently reduce the ash content. Wood biomass-derived products manufactured from such biomass raw materials have problems such as reduced quality, combustion problems, and deterioration of properties.

[0015] Therefore, in order to solve the problems described in Patent Document 1, the present inventors conducted diligent research and, as a result, invented the following method for producing woody biomass pulverized material.

[0016] A method for producing a woody biomass-derived product according to the embodiments of this disclosure comprises a processing step and a manufacturing step. The processing step includes a sieving step. The sieving step involves passing the woody biomass pulverized material through a screen with an opening of 400 μm or more, separating it into sieved material remaining on the screen and unsieved material that has passed through the screen, and recovering the sieved material. The manufacturing step produces a woody biomass-derived product from at least one of the sieved material and compressed woody biomass obtained by compressing the sieved material.

[0017] Therefore, the method for producing woody biomass-derived products according to the present disclosure has the above-mentioned characteristics, which allows for the removal of insoluble inorganic components and the obtaining of woody biomass pulverized material that sufficiently reduces the ash content of the woody biomass, and provides woody biomass-derived products of good quality produced from the woody biomass pulverized material.

[0018] (2) Details The embodiments described below are only a part of the various embodiments of this disclosure. Furthermore, the embodiments described below can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. In addition, the mechanisms of operation in the embodiments may be described, but these descriptions of the mechanisms of operation include explanations based on speculation, and this disclosure is not bound by the descriptions of the mechanisms of operation.

[0019] (First Embodiment) A method for producing woody biomass-derived products according to the first embodiment (hereinafter also referred to as manufacturing method (A)) will be described. In manufacturing method (A) according to the first embodiment, the processing step includes a sieving step. That is, manufacturing method (A) according to the first embodiment has, in the order in which it is carried out, a crushing step, a sieving step as a processing step, and a manufacturing step.

[0020] <Crushing Process> The crushing process is a process of converting the raw material, woody biomass, into woody biomass crushed material (hereinafter also referred to as crushed material). The woody biomass is not particularly limited, but examples include palm plants, hemp, bamboo, and grasses. Among the above, palm plants are preferred, palm waste is more preferred, and oil palm waste is even more preferred. In this case, it is possible to contribute to the resource recovery of unused resources and the resolution of environmental problems. The crushing method is not particularly limited, but examples include crushing using a hammer mill, cutter mill, chipper, ball mill, etc. Crushing may be performed only once or two or more times. The size of the crushed material obtained by crushing is not particularly limited. It is preferable to remove foreign matter from the obtained crushed material using a foreign matter removal machine. The foreign matter removal machine is not particularly limited, and known foreign matter removal machines can be used.

[0021] <Processing Steps> As described above, the processing steps include a sieving step. By performing the sieving step, the ash content of the woody biomass pulverized material can be reduced.

[0022] ≪Sieving Process≫ The sieving process involves separating the pulverized material into sieved material and unsieved material using a screen, and then recovering the sieved material remaining on the screen. In other words, the sieved material and unsieved material are pulverized materials that have been classified by the screen. The unsieved material contains more inorganic components, including ash attached to the dried pulverized material, and powdered short fibers than the sieved material, and these can be separated and removed from the pulverized material through the sieving process.

[0023] Inorganic components containing ash include, for example, calcium, potassium, magnesium, silica, sulfur, sodium, boron, cesium, and iron.

[0024] The pulverized short fibers include, for example, parenchymal cell tissue. Parenchymal cell tissue is tissue composed of parenchymal cells. Parenchymal cell tissue includes assimilated tissue, secretory tissue, and storage tissue, and has physiological functions such as synthesis, decomposition, and storage. The pulverized material mainly composed of parenchymal cell tissue is finely powdered and smaller than the pulverized material mainly composed of other vascular bundles. When the pulverized material contains parenchymal cell tissue, it can lead to poor drying of the pulverized material, as well as a decrease in strength and variation in quality of the woody biomass-derived product produced from this pulverized material. Therefore, it is preferable to remove the pulverized short fibers containing parenchymal cell tissue from the pulverized material.

[0025] It is preferable to dry the pulverized material used in the sieving process. Drying makes it easier to remove inorganic components from the pulverized material. The moisture content of the dried pulverized material is preferably 100% by mass or less. In this case, the inorganic components, including ash, are dried along with the pulverized material, and water-soluble inorganic components precipitate, so that more inorganic components are removed in the sieving process and the ash content of the pulverized material is further reduced. In addition, the removed components such as ash are less likely to adhere to the screen, improving workability.

[0026] The mesh size of the screen used in the sieving process is 400 μm or larger. Preferably, the mesh size is 2000 μm or smaller, and more preferably 800 μm or smaller. When the mesh size of the screen is within the above range, the inorganic components of the dried pulverized material can be removed. In other words, the ash content of the pulverized material can be reduced, and in particular, the ash content of particles smaller than or equal to a screen mesh size of 400 μm can be reduced, so the ash content of the pulverized material can be reduced to 2% by mass or less. Furthermore, a good recovery rate of the pulverized material can be achieved.

[0027] Since the separation of pulverized material by screen is a dry physical separation, inorganic components are separated regardless of whether they are water-soluble or insoluble. Furthermore, foreign matter such as soil that could not be completely removed in upstream processes such as foreign matter removal, as well as fine powder and short fibers of pulverized material containing parenchymal cell tissue, can be removed simultaneously and easily. In addition, since the sieving process is carried out by gravity, centrifugal force, etc., inorganic components, which have a higher specific gravity than the wood fibers of the pulverized material, are particularly easily separated. The screen used in the sieving process is not particularly limited as long as it has a mesh size within the above range, and can be either a vibrating type or a rotary type.

[0028] The length and diameter of the pulverized material recovered as sieved material after the sieving process are preferably 0.4 mm to 50.0 mm in length and 0.10 mm to 1.00 mm in diameter (hereinafter, pulverized material in this range may be referred to as "large-size pulverized material"). If the length and diameter of the pulverized material are within the above range, the strength of the woody biomass-derived product manufactured from this pulverized material can be improved, and the decrease in surface smoothness of the woody biomass-derived product can be suppressed.

[0029] The length and diameter of large-sized particles in the pulverized material can be measured as follows: For a predetermined amount of classified pulverized material, the length and diameter of each particle are measured using a magnifying glass, microscope, etc., and the arithmetic mean of the results is calculated.

[0030] The content of large-sized pulverized material relative to the total amount of pulverized material is preferably 70% by mass or more, more preferably 75% by mass or more. In this case, the strength of the woody biomass-derived product produced from this pulverized material can be improved. The upper limit of the content of large-sized pulverized material is not particularly limited, but for example, it is 100% by mass or less.

[0031] The amount of large-sized pulverized material contained in the pulverized material after the sieving process is determined by measuring the length and diameter of a predetermined amount of the classified pulverized material using a magnifying glass, microscope, etc., and classifying it based on whether or not it falls within the range of length 0.4 mm to 50.0 mm and diameter 0.10 mm to 1.00 mm. The mass ratio of material within this range (large-sized pulverized material) to material not within this range is then determined.

[0032] <Manufacturing Process> The manufacturing process involves producing wood biomass-derived products from at least one of the following: the pulverized material recovered in the sieving process, and the compressed wood biomass material (hereinafter also referred to as "compressed material") obtained by compressing this sieved material. In other words, wood biomass-derived products may be manufactured using the pulverized material or using the compressed material.

[0033] As mentioned above, woody biomass-derived products include, for example, wood-based boards, fuel pellets, and papermaking pulp. The manufacturing method for woody biomass-derived products is not particularly limited and can be manufactured by an appropriate method depending on the desired product.

[0034] Compressed materials are obtained by compressing pulverized material to reduce its bulk density. Advantages of compressing pulverized material include improved storage and transportability. The shape of the compressed material is not particularly limited, but examples include pellets, tablets, briquettes, blocks, and plates. Pellet-shaped compressed materials can be obtained using known pelletizers such as flat-die or ring-die molds. Tablet-shaped compressed materials can be obtained using known tablet presses with molds having cavities corresponding to the shape of the compressed material. Briquette-shaped compressed materials can be obtained using known briquetters, such as a mold with open ends. In this mold, pulverized material is introduced into the mold with an already formed compressed material placed on one open end, and the pulverized material is compressed by applying pressure from the other open end while simultaneously advancing the compressed material. Block-shaped compressed materials can be obtained using known volume reducers, such as a single-shaft volume reducer that compresses the pulverized material from the open end of a frame, or a three-shaft volume reducer that compresses from three directions. The compressed sheet material can be obtained by stacking crushed material to form a mat, and then compressing the mat in the thickness direction. When compressing the crushed material, adhesive is not used; the material is integrated by compressive force alone. However, adhesive may be used as long as it does not hinder the production of woody biomass-derived products.

[0035] Since the compressed material is manufactured from the pulverized material obtained by the above processing method, insoluble inorganic components of the woody biomass are removed, and the ash content is reduced. Specifically, the ash content of particles smaller than or equal to a screen opening of 400 μm is reduced, and the ash content of the compressed material is 2% by mass or less.

[0036] Fuel pellets can be manufactured, for example, by compressing crushed material into a material using the method described above, so that it conforms to the dimensions specified in JAS0030:2023.

[0037] Papermaking pulp is obtained by defibrating crushed and compressed materials. Defibration can be carried out by mechanical or chemical treatment. In mechanical treatment, for example, the crushed and compressed materials are defibrated by shearing them with machines such as crushers, cutters, and dry defibration machines. In chemical treatment, for example, the crushed and compressed materials are defibrated by steaming them at high temperature and pressure and adding chemicals. Paper can then be manufactured from the obtained pulp by papermaking and drying. Papermaking can be carried out using, for example, a wire screen papermaking machine, a cylinder screen papermaking machine, or a hand papermaking machine. Drying can be carried out by, for example, drying the pulp after papermaking using a dryer until it reaches a predetermined moisture content.

[0038] Examples of wood-based boards include insulation boards, medium-density fiberboards, hardboards, and particleboards. Wood-based boards can be manufactured by decomposing crushed and compressed materials to obtain raw materials, and then undergoing appropriate processing such as heat compression, wet papermaking, and drying. The decomposition of crushed and compressed materials is carried out using the same processing methods as described above for defibration.

[0039] (Second Embodiment) A manufacturing method (A) according to the second embodiment will now be described. In the manufacturing method (A) according to the second embodiment, the processing steps include a sieving step and a water-compression step performed before the sieving step. That is, the manufacturing method (A) according to the second embodiment has, in order of being performed, a crushing step, a water-compression step and a sieving step as processing steps, and a manufacturing step. The second embodiment differs from the first embodiment in that it has a water-compression step. Note that the water-compression step may be called a washing step. Furthermore, explanations of the same configuration as in the first embodiment will be omitted as appropriate.

[0040] <Processing Steps>As described above, the processing steps include a screening step and a hydro-compression step performed before the screening step. By performing the hydro-compression step, the ash content of the pulverized woody biomass can be further reduced, and the sugar content of the pulverized woody biomass can be reduced. Since the screening step is the same as that of the first embodiment, the description thereof is omitted.

[0041] <<Hydro-Compression Step>>The hydro-compression step includes a water addition step of adding water to the pulverized material to make it contain water, and a compression step of compressing the water-added pulverized material to discharge water together with water-soluble inorganic components.

[0042] The water addition step is a step of making the pulverized material contain water to increase the water content. Here, the water content is the ratio of the mass of water to the mass of woody biomass (including pulverized woody biomass and compressed woody biomass) in a state where it contains no water at all (hereinafter referred to as the completely dry state). The method of adding water is not particularly limited, and examples include spraying water using a sprayer or a spray, sprinkling water from a hose or a nozzle, and immersing in a water storage tank. By adding water to the pulverized material, the water content of the pulverized material increases, and inorganic components including water-soluble ash are eluted into the added water. The water addition step may be performed not only on the pulverized material obtained by pulverizing the raw material woody biomass but also on the pulverized material compressed in the compression step and discharged from the compression processing device.

[0043] The water content of the pulverized material after the water addition step is preferably 150% by mass or more, more preferably 200% by mass or more, and still more preferably 250% by mass or more. In this case, the inorganic components and sugar content in the pulverized material can be sufficiently removed. The water content of the pulverized material after the water addition step is preferably 600% by mass or less, more preferably 550% by mass or less, and still more preferably 500% by mass or less. In this case, the water discharged from the pulverized material by compression can be used as a raw material for fuel or the like.

[0044] The compression process involves using a compression apparatus to remove water from the pulverized material or water-soluble inorganic components and sugars, including ash, from the pulverized material, thereby reducing the content of water-soluble inorganic components and sugars in the pulverized material. The compression apparatus is not particularly limited, but examples include belt presses, rotary shaft compression dewaterers with blades, flat plate presses, roll presses, and vacuum dewaterers. The rotary shaft of a rotary shaft compression dewaterer with blades may be one shaft or two or more shafts. Compression apparatuses can be continuous or batch type, but continuous type is preferred from the viewpoint of work efficiency, and among the above-mentioned compression apparatuses, rotary shaft compression dewaterers with blades are particularly preferred.

[0045] Furthermore, the compression process may be performed only once on the pulverized material, or it may be performed two or more times. If it is performed two or more times, it is more preferable to perform it on the pulverized material after it has undergone a water addition process again after the compression process. In other words, the water addition and compression process may be performed two or more times on the pulverized material. Moreover, if the compression process is performed two or more times, the same compression apparatus may be used for each compression process, or different compression apparatuses may be used.

[0046] To improve the efficiency of removing inorganic components and sugars from the pulverized material, it is preferable to control the temperature of the pulverized material during the compression process. The best time to measure the temperature of the pulverized material is immediately before or immediately after discharge, when the pulverized material has been exposed to compressive and shearing forces for the longest time and its temperature is at its highest. The method of measuring the temperature is not particularly limited, but it may be measured by installing sensors or thermocouples inside the compression apparatus, or by using a contact thermometer or non-contact thermometer on the pulverized material immediately after discharge from the compression apparatus. Furthermore, the moisture discharged from the pulverized material during compression is considered to be at the same temperature as the pulverized material. Therefore, the temperature of the moisture discharged from the pulverized material during compression may be used as a substitute for the temperature of the pulverized material.

[0047] The method for controlling the temperature of the pulverized material during the compression process is not particularly limited, but examples include control using a temperature controller, control of the amount of pulverized material supplied to the compression apparatus, and the conveying speed of the pulverized material within the compression apparatus.

[0048] The temperature of the pulverized material during the compression process is preferably 25°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher. In this case, inorganic components and sugars in the pulverized material become more readily eluted by water, making it easier to remove them. The temperature of the pulverized material is preferably 85°C or lower, more preferably 80°C or lower. In this case, gelatinization of starch in the pulverized material can be suppressed, making it easier for inorganic components and sugars in the pulverized material to dissolve by water, making it easier to remove them.

[0049] (Third Embodiment) A manufacturing method (A) according to the third embodiment will now be described. In the manufacturing method (A) according to the third embodiment, the processing steps include two sieving steps and a water-compression step performed before these sieving steps. That is, the manufacturing method (A) according to the third embodiment has, in the order in which it is performed, a crushing step, a water-compression step and two sieving steps as processing steps, and a manufacturing step. The third embodiment differs from the second embodiment in that the sieving step is repeated twice. The same configurations as in the first and second embodiments will be omitted from the explanation as appropriate.

[0050] <Processing Steps> As described above, the processing steps include two sieving steps and a water-compression step performed before the sieving steps. By repeating the sieving steps twice, the ash content of the woody biomass pulverized material can be further reduced. The water-compression step is the same as in the second embodiment, so its explanation is omitted.

[0051] ≪Sieving Process≫ In the manufacturing method of this embodiment, the sieving process is repeated twice. Specifically, the first separation is performed by the sieving process, similar to the second embodiment, and the material below the sieve is collected. The material below the sieve collected in the first separation is screened again to perform a second separation, and the material above the sieve from the second separation is collected. In this embodiment, the separation by the sieving process is performed twice, but it may be performed three or more times. Both the material above the sieve collected in the first separation and the material above the sieve collected in the second separation can be used in the manufacture of woody biomass-derived products.

[0052] The mesh size of the screen used in the sieving process of this embodiment is within the same range as in other embodiments. However, when the sieving process is repeated multiple times, it is preferable to use a screen with the same mesh size as the screen used in the previous sieving process, or a screen with a smaller mesh size. In this case, inorganic components including ash can be removed more effectively, and the recovery rate (fiber yield) of the pulverized material can be improved.

[0053] As described above, when performing the sieving process multiple times, if a screen with a smaller mesh size is used than the previous sieving process, the size of the recovered pulverized material will decrease with each subsequent sieving. In other words, further classification of the pulverized material occurs within the larger sized pulverized material. These large sized pulverized materials of different sizes may be mixed together after recovery, or they may be used separately depending on the purpose and desired physical properties.

[0054] Furthermore, if the sieving process is performed multiple times, the frequency of removal of inorganic components from the pulverized material increases, potentially further reducing the ash content of the pulverized material. In other words, if the sieving process is performed multiple times, it is presumed that the sieved material obtained in the first sieving process will have the highest ash content, and the ash content of the sieved material will decrease with each subsequent sieving.

[0055] (3) Embodiments As will be clear from the above embodiments and modifications, the present disclosure includes the following embodiments.

[0056] The first embodiment is a method for producing a woody biomass-derived product, comprising a processing step and a manufacturing step. The processing step includes a sieving step. In the sieving step, woody biomass pulverized material is passed through a screen with an opening of 400 μm or more, separating it into sieved material remaining on the screen and unsieved material that has passed through the screen, and the sieved material is recovered. In the manufacturing step, a woody biomass-derived product is produced from at least one of the sieved material and compressed woody biomass obtained by compressing the sieved material.

[0057] According to this embodiment, it is possible to obtain woody biomass pulverized material from which insoluble inorganic components can be removed and the ash content can be reduced, and to provide woody biomass-derived products of good quality produced from the woody biomass pulverized material.

[0058] A second embodiment is a method for producing woody biomass-derived products based on the first embodiment. In the second embodiment, the processing step further includes a water-compression step in which water is added to the woody biomass pulverized material and compressed before the sieving step.

[0059] According to this embodiment, the ash content of the woody biomass pulverized material can be further reduced, resulting in a higher quality woody biomass-derived product.

[0060] The third aspect is a method for producing woody biomass-derived products based on the second aspect. In the third aspect, during the water-compression step, the moisture content of the woody biomass pulverized material is 150% by mass or more and 600% by mass or less, and the temperature of the woody biomass pulverized material is 25°C or more and 85°C or less.

[0061] According to this embodiment, the ash content of the woody biomass pulverized material can be further reduced, resulting in a superior woody biomass-derived product.

[0062] A fourth aspect is a method for producing a woody biomass-derived product based on the second or third aspect. In the fourth aspect, the water-compression step is repeated at least twice.

[0063] According to this embodiment, the ash content of the woody biomass pulverized material can be further reduced, resulting in a superior woody biomass-derived product.

[0064] The fifth aspect is a method for producing a woody biomass-derived product based on any one of the first to fourth aspects. In the fifth aspect, the mesh size of the screen is 2000 μm or less.

[0065] According to this embodiment, the fiber yield of woody biomass pulverized material can be improved, insoluble inorganic components can be removed, and the ash content can be further reduced, resulting in a superior woody biomass-derived product.

[0066] The sixth aspect is a method for producing a woody biomass-derived product based on any one of the first to fifth aspects. In the sixth aspect, the sieving process is repeated at least twice.

[0067] According to this embodiment, the fiber yield of woody biomass pulverized material can be improved, insoluble inorganic components can be removed, and the ash content can be further reduced, resulting in a superior woody biomass-derived product.

[0068] The seventh aspect is a method for producing a woody biomass-derived product based on any one of the first to sixth aspects. In the seventh aspect, the woody biomass pulverized material contains 70% by mass or more of fibers having a length of 0.4 mm or more and a diameter of 50.0 mm or less, and a diameter of 0.10 mm or more and 1.00 mm or less.

[0069] According to this embodiment, the strength of woody biomass-derived products can be improved, and the decrease in surface smoothness of woody biomass-derived products can be suppressed.

[0070] The eighth aspect is a method for producing a woody biomass-derived product based on any one of the first to seventh aspects. In the eighth aspect, the woody biomass-derived product includes coconut waste.

[0071] According to this embodiment, coconut waste can be effectively utilized.

[0072] The ninth aspect is a woody biomass-derived product containing woody biomass pulverized material that does not contain ash particles smaller than or equal to the size of a screen opening of 400 μm, wherein the ash content relative to the total amount of woody biomass pulverized material is 2% by mass or less.

[0073] According to this embodiment, the ash content of the woody biomass pulverized material is sufficiently reduced, and it can be utilized in the production of woody biomass-derived products such as wood boards, fuel pellets, and paper pulp.

[0074] The tenth embodiment is a wood biomass-derived product containing wood biomass compressed material obtained by compressing wood biomass pulverized material that does not contain ash with a mesh size equivalent to 400 μm or less of the screen opening, wherein the ash content is 2% by mass or less of the total amount of wood biomass compressed material.

[0075] According to this embodiment, the ash content of the compressed woody biomass is sufficiently reduced, and it can be utilized in the production of woody biomass-derived products such as wood boards, fuel pellets, and paper pulp.

[0076] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0077] (Example 1) As the raw material, empty fruit clusters (EFB) were collected from oil palm waste as woody biomass, and these EFB were crushed in a hammer mill to obtain a pulverized product (crushing step). Next, the pulverized product was placed in a dryer set to 105°C and dried for 30 minutes (drying step). After drying, the product was placed on screen #1 with a mesh size of 2000 μm and sieved for 10 seconds to perform sieving (first sieving step), and the woody fibers remaining on screen #1 were used as the sample.

[0078] (Example 2) The same grinding process as in Example 1 was carried out to obtain a pulverized material. Water was sprayed onto this pulverized material to a moisture content of 200% by mass (water addition step). This water-added pulverized material was fed into a rotary shaft compression dewatering machine with blades and compressed under the following conditions: average temperature of the pulverized material during compression: 40°C, compression time: 30 seconds, moisture content of the compressed material upon discharge from the rotary shaft compression dewatering machine with blades: 80% by mass, to obtain a compressed material (compression step). The water addition step and compression step under the same conditions as above were carried out again on the obtained compressed material to obtain a new compressed material. Subsequently, the same drying step and first sieving step as in Example 1 were carried out on this compressed material, and the wood fibers remaining on the sieve on screen #1 were used as the sample.

[0079] (Example 3) The same procedure as in Example 2 was followed from the crushing process to the first sieving process. Next, the compressed material that fell from screen #1 was placed into screen #2, which has a mesh opening of 600 μm, and sieved for 10 seconds to perform another sieving process (second sieving process). The woody fibers remaining on screen #2 were used as the sample.

[0080] (Example 4) A sample was obtained in the same manner as in Example 3, except that the screen used in the second sieving step of Example 3 was changed to Screen #3 with a mesh size of 425 μm.

[0081] (Comparative Example 1) In the same procedure as in Example 1, the grinding process to the drying process was carried out to obtain a dried grind, and this grind was used as a sample.

[0082] (Comparative Example 2) In the same procedure as in Example 2, the process from the grinding process to the second compression process was carried out to obtain a hydro-compressed grind, and this grind was used as a sample.

[0083] (Comparative Example 3) A sample was obtained in the same manner as in Example 2, except that the screen used in the first sieving step of Example 2 was changed to Screen #4 with a mesh size of 300 μm.

[0084] <Evaluation Method> The evaluation method for the wood fiber obtained as a sample is described below.

[0085] <<Content of Ash>> The sample was put into a dryer set at 105 °C and dried for 24 hours to obtain a completely dry state. The completely dry state means a state where the wood fiber contains no moisture at all. This sample in the completely dry state was put into an ashing container, and then, based on "Measurement of Ash" in Appendix G of JAS (Japanese Agricultural Standard) 0030, it was heated in a high-temperature furnace at 550 °C for ashing. Then, the content of ash of each sample was calculated by the following formula.

[0086] A ｄ (mass%) = (m ３ - m １ ) / (m ２ - m １ ) × 100 A ｄ : Content of ash of the sample m １ : Mass of the empty ashing container m ２ : Total mass of the ashing container and the sample m ３ : Total mass of the ashing container and the ashed sample The content of ash is preferably 2 mass% or less based on the total amount of the sample.

[0087] ≪Fiber Yield≫ The mass of the wood fibers and the obtained sample before the sieving process was measured, and the fiber yield was calculated using the following formula. Note that if a second sieving process was performed, "before the sieving process" refers to the period before the second sieving process, and "recovered sample" refers to the wood fibers remaining on the screen used in the second sieving process. Furthermore, in Comparative Examples 1 and 2, where no sieving process was performed, the fiber yield was assumed to be 100%.

[0088] Fiber yield (%) = B / A × 100 A: Mass of wood fibers before the sieving process B: Mass of the sample remaining on the screen and recovered The fiber yield is preferably 50% or more.

[0089]

[0090]

[0091] Table 1 shows the conditions and evaluation results for each example and comparative example, and Table 2 shows the mesh size of each screen. As shown in Table 1, Examples 1 to 4, in which the first sieving process was carried out using screens with a mesh size of 400 μm or more and 2000 μm or less, reduced the ash content to 2% by mass or less while maintaining the fiber yield. Furthermore, Examples 3 and 4, in which the second sieving process was carried out, showed a further reduction in ash content. On the other hand, it was confirmed that Comparative Examples 1 and 2, in which the first sieving process was not carried out, and Comparative Example 3, in which the first sieving process was carried out using a screen with a mesh size of 400 μm or less, had an ash content of 2% by mass or more.

Claims

1. A method for producing a woody biomass-derived product, comprising: a processing step including a sieving step in which woody biomass pulverized material is passed through a screen with a mesh opening of 400 μm or more, separating the sieved material remaining on the screen from the unsieved material that has passed through the screen, and recovering the sieved material; and a manufacturing step in which a woody biomass-derived product is produced from at least one of the sieved material and compressed woody biomass obtained by compressing the sieved material.

2. The method for producing a woody biomass-derived product according to claim 1, wherein the processing step further includes a water-adding and compression step of adding water to the woody biomass pulverized material and compressing it before the sieving step.

3. The method for producing a woody biomass-derived product according to claim 2, wherein in the water-adding and compression step, the moisture content of the woody biomass pulverized material is 150% by mass or more and 600% by mass or less, and the temperature of the woody biomass pulverized material is 25°C or more and 85°C or less.

4. A method for producing a woody biomass-derived product according to claim 2 or 3, wherein the water-adding and compression step is repeated at least twice.

5. A method for producing a woody biomass-derived product according to any one of claims 1 to 4, wherein the mesh opening of the screen is 2000 μm or less.

6. A method for producing a woody biomass-derived product according to any one of claims 1 to 5, wherein the sieving step is repeated at least twice.

7. A method for producing a woody biomass-derived product according to any one of claims 1 to 6, wherein the woody biomass pulverized material contains 70% by mass or more of fibers having a length of 0.4 mm or more and a diameter of 0.10 mm or more and 1.00 mm or less.

8. A method for producing a woody biomass-derived product according to any one of claims 1 to 7, wherein the woody biomass pulverized material includes coconut waste.

9. A woody biomass-derived product containing woody biomass pulverized material that does not contain ash particles smaller than or equal to a screen opening of 400 μm, and wherein the ash content relative to the total amount of woody biomass pulverized material is 2% by mass or less.

10. A wood biomass-derived product containing compressed wood biomass that is made from wood biomass pulverized material that does not contain ash particles with a screen opening of 400 μm or less, wherein the ash content relative to the total amount of the compressed wood biomass is 2% by mass or less.

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