Biomass solid fuel, method for firing biomass solid fuel, and method for producing biomass solid fuel

Abstract

The present disclosure provides a biomass solid fuel which contains two or more biomass carbides, wherein the contents of mannose, xylose, arabinose, and glucose that are contained as constituent sugars are 1.3-8.0 mass%, 2.5-3.8 mass%, 1.0 mass% or less, and 40.0-52.7 mass%, respectively.

Description

Biomass solid fuel, method for calcining biomass solid fuel, and method for producing biomass solid fuel

[0001] This disclosure relates to a biomass solid fuel, a method for calcining a biomass solid fuel, and a method for producing a biomass solid fuel.

[0002] Conventionally, biomass solid fuels using biomass have been known. Biomass solid fuels are expected to be an alternative to fossil fuels. Patent Document 1 discloses a biomass solid fuel with reduced chemical oxygen demand (COD) of wastewater. Patent Document 2 discloses a method for producing a biomass solid fuel with reduced self-heating properties while suppressing disintegration during production. Patent Document 3 discloses a method for producing a biomass solid fuel with excellent water resistance using biomass raw materials that are easy to cultivate and harvest on a commercial scale. Non-Patent Documents 1 and 2 describe methods for analyzing the constituent sugars of biomass.

[0003] International Publication No. 2016 / 056608, Japanese Patent Publication No. 2020-033396, U.S. Patent Application Publication No. 2022 / 0306958

[0004] A. Sluiter et. al., “Determination of Structural Carbohydrates and Lignin in Biomass”, [online], pp. 3-8, August 2012, National Renewable Energy Laboratory, [Retrieved March 7, 2023], Internet<URL:https: / / www.nrel.gov / docs / gen / fy13 / 42618.pdf> Momoko Kondo et al., "Initiatives for Contract Analysis of Constituent Sugars in Woody Biomass," Biomass Section, Japan Energy Society, Proceedings of the 12th Biomass Science Conference, January 2017, pp. 159-160.

[0005] Biomass solid fuels are prone to spontaneous combustion during storage, and therefore, measures are taken to prevent ignition, such as by spraying water, to prevent the internal temperature from rising during shipping or when stacked and stored at power plants. This disclosure provides a biomass solid fuel that suppresses spontaneous combustion during storage, a method for calcining a biomass solid fuel, and a method for producing a biomass solid fuel.

[0006] One aspect of this disclosure is the provision of a biomass solid fuel comprising two or more biomass chars, wherein the constituent sugars include a mannose content of 1.3 to 8.0% by mass, a xylose content of 2.5 to 3.8% by mass, an arabinose content of 1.0% by mass or less, and a glucose content of 40.0 to 52.7% by mass.

[0007] The above-mentioned solid fuel contains two or more types of biomass char, and is a biomass char containing predetermined amounts of mannose, xylose, arabinose, and glucose as constituent sugars. Such a solid fuel can suppress spontaneous combustion during storage.

[0008] One aspect of this disclosure is the provision of a method for calcining biomass solid fuel, which includes the step of calcining the biomass solid fuel described above.

[0009] The above method for firing biomass solid fuel involves firing a biomass solid fuel that contains two or more types of biomass carbonized material and predetermined amounts of mannose, xylose, arabinose, and glucose as constituent sugars.

[0010] One aspect of this disclosure provides a method for producing a biomass solid fuel, comprising the step of mixing two or more types of biomass char to obtain a mixture, wherein the mixture contains 1.3 to 8.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.7% by mass of glucose as constituent sugars.

[0011] The above method for producing solid fuel includes a step of mixing two or more types of pre-carbonized biomass charred materials (for example, biomass charred material X and biomass charred material Y) to obtain a mixture, the mixture containing predetermined amounts of mannose, xylose, arabinose, and glucose as constituent sugars. By mixing two or more types of biomass charred materials, the proportion of constituent sugars in the biomass solid fuel can be easily adjusted by adjusting the blending of biomass charred materials X and Y in the mixture. Solid fuel obtained by this method can suppress spontaneous combustion during storage.

[0012] This disclosure provides a biomass solid fuel that suppresses spontaneous combustion during storage, a method for calcining the biomass solid fuel, and a method for producing the biomass solid fuel.

[0013] This graph shows the relationship between the acacia char content in Examples 1-5 and Comparative Examples 1-3 and the maximum temperature reached by the wire basket test.

[0014] Embodiments of the present disclosure are described below. However, the following embodiments are illustrative for the purpose of illustrating the present disclosure and are not intended to limit the present disclosure to the following. The upper or lower limits of numerical ranges explicitly stated in the present disclosure may be replaced with any of the values ​​shown in the examples. Furthermore, the upper and lower limits described individually may be combined in any way. Unless otherwise specified, the materials or components illustrated in the present disclosure may be used individually or in combination of two or more. The symbol "~" used in numerical ranges indicates a numerical range that includes the upper and lower limits. For example, "X~Y" indicates a numerical range of "X or greater and Y or less".

[0015] In this disclosure, "absolutely dry state" means the state after the object to be measured (e.g., biomass solid fuel and biomass carbonized material) has been heated at 107°C for 4 hours or more and has reached a constant weight.

[0016] [Biomass Solid Fuel] A biomass solid fuel according to one embodiment contains two or more types of biomass chars. The biomass solid fuel contains 1.3 to 8.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.7% by mass of glucose as constituent sugars.

[0017] In biomass solid fuel, two or more types of biomass chars may coexist. For example, it may be a powder made by mixing finely ground particles of each type, or the powder may be formed into briquettes. Alternatively, pellets of two or more types of biomass chars may be left in their original state without being finely ground. Furthermore, the biomass solid fuel may be in the form of pellets containing two or more types of biomass chars, in bags in flexible containers, or piled up in a stockyard. In other words, it is sufficient that the two types of biomass chars can be co-fired when the biomass solid fuel is burned in a boiler. Note that the biomass solid fuel may contain components other than biomass chars, or it may consist only of two or more types of biomass chars. For example, if the biomass solid fuel contains two types of biomass chars, they may be referred to as biomass char A and biomass char B, respectively.

[0018] The two or more types of biomass char may be a mixture of biomass char from different tree species. The biomass used as raw material for the biomass char may be, for example, bagasse, acacia, conifers, rubber trees, eucalyptus, meranti, teak, oil palm trunks, empty palm fruit clusters, sorghum, and Napier grass. Examples of conifers include cedar, cypress, larch, hinoki cypress, fir, spruce, radiata pine, Scots pine, and hemlock. These may be used individually or in combination of two or more. For example, it is preferable to include 10 to 50% by mass or 20 to 40% by mass of spruce, 30 to 60% by mass or 40 to 50% by mass of pine, and 10 to 40% by mass or 20 to 30% by mass of fir. The biomass charred material may be obtained by heating each of these biomass materials to produce two or more types of biomass charred material, such as hardwood charred material and coniferous charred material. In other words, the two or more types of biomass charred material mentioned above may be two or more types of biomass charred material selected from the group consisting of, for example, bagasse charred material, acacia charred material, coniferous charred material, rubber tree charred material, eucalyptus charred material, meranti charred material, teak charred material, oil palm trunk charred material, palm fruit cluster charred material, sorghum charred material, and Napier grass charred material. The two or more types of biomass charred material may include one or more types of hardwood charred material and one or more types of coniferous charred material.

[0019] The two or more biomass chars may be a mixture of at least two biomass chars with different maximum temperatures measured in the wire basket test. The two or more biomass chars may include at least two biomass chars with different maximum temperatures measured in the wire basket test. The wire basket test is a test to evaluate self-heating properties and can be performed in accordance with the UN recommended test method "Manual of Tests and Criteria 7th edition", 33.4.6 Test N.4: Test Method for self-heating Substances. By using a mixture of biomass chars with different maximum temperatures, the maximum temperature reached in the biomass solid fuel can be reduced. This can further suppress spontaneous combustion during storage of the biomass solid fuel.

[0020] In the case of biomass solid fuel, the maximum temperature reached as measured in the wire basket test described above may be less than 200°C, 190°C or less, 180°C or less, or 170°C or less. By keeping the maximum temperature reached of the biomass solid fuel within the above range, spontaneous combustion during storage of the biomass solid fuel can be suppressed. The maximum temperature reached of the biomass solid fuel may also be 100°C or higher. The range of the maximum temperature reached of the biomass solid fuel may be, for example, 100°C or more but less than 200°C, 100 to 190°C, 100 to 180°C, or 100 to 170°C.

[0021] In biomass solid fuel, the mannose content as a constituent sugar is 1.3 to 8.0% by mass. From the viewpoint of suppressing spontaneous combustion during storage and suppressing pulverization of biomass solid fuel, the mannose content as a constituent sugar may be 1.5 to 7.0% by mass, or 2.0 to 7.0% by mass.

[0022] In the biomass solid fuel, the content of xylose contained as a constituent sugar is 2.5 to 3.8% by mass. From the viewpoint of suppressing spontaneous ignition during storage and suppressing pulverization of the biomass solid fuel, the content of xylose contained as a constituent sugar may be 3.0 to 3.7% by mass, or 3.0 to 3.6% by mass.

[0023] In the biomass solid fuel, the content of arabinose contained as a constituent sugar is 1.0% by mass or less. The content of arabinose contained as a constituent sugar may be 0.5% by mass or less. Arabinose may not be contained in the biomass solid fuel, but for example, arabinose as a constituent sugar may be contained to such an extent that a trace amount is detected, may be more than 0% by mass, or may be 0.1% by mass or more. That is, the content of arabinose contained as a constituent sugar may be more than 0% by mass and 1.0% by mass or less, 0.1 to 1.0% by mass, or 0.1 to 0.5% by mass.

[0024] In the biomass solid fuel, the content of glucose contained as a constituent sugar is 4 about 0.0 to 52.7% by mass. From the viewpoint of suppressing spontaneous ignition during storage and suppressing pulverization of the biomass solid fuel, the content of glucose contained as a constituent sugar may be 45.0 to 52.5% by mass, or 48.0 to 52.0% by mass.

[0025] In the biomass solid fuel, the content of galactose contained as a constituent sugar may be 0.05 to 1.5% by mass, or 0.1 to 1.3% by mass.

[0026] Monosaccharides such as mannose, xylose, arabinose, glucose, and galactose constitute the polysaccharides contained in biomass solid fuel. Since polysaccharides have a large molecular weight, their content cannot be directly measured by analytical instruments. Therefore, in the present disclosure, the content of polysaccharides is determined, for example, by measuring the content of constituent sugars obtained by hydrolyzing the polysaccharides in a sample with an acid using HPLC or GC, etc., and multiplying by a polysaccharide conversion factor considering the over-decomposition of the constituent sugars. The analytical method for the constituent sugars of biomass can be measured, for example, by the method described in Non-Patent Document 1 or Non-Patent Document 2. In the present disclosure, the content of each monosaccharide as a constituent sugar means the content of each monosaccharide detected by the method described in Non-Patent Document 1 or Non-Patent Document 2, and does not necessarily identify that it exists as a monosaccharide in the biomass solid fuel.

[0027] The analytical method for the content of constituent sugars can be determined, for example, by adding 3 mL of 72% by mass sulfuric acid to 0.3 g of biomass solid fuel, reacting at 30 °C for 1 hour, filtering the reaction solution, and analyzing the filtrate by HPLC or GC-MS. Since GC-MS has high versatility and excellent selectivity, it is preferable to use GC-MS. Specifically, the content of constituent sugars can be determined by the method described in the examples.

[0028] In the above analytical method, the contents of glucose, galactose, arabinose, xylose, mannose, etc. can be measured as the constituent sugars constituting the polysaccharides. By multiplying the measurement results by the polysaccharide conversion factor for each constituent sugar, the content of the polysaccharides having each constituent sugar can be regarded as. Examples of polysaccharides include glucan, galactan, arabinan, xylan, and mannan. The biomass solid fuel may contain at least one of such polysaccharides. The biomass solid fuel may contain, for example, glucan and xylan. On the other hand, the biomass solid fuel does not have to contain mannan, arabinan, and galactan. In the present disclosure, not containing a constituent sugar or a polysaccharide indicates that it is below the detection limit.

[0029] The biomass used as a raw material may contain the polysaccharides mentioned above. Furthermore, a material in which at least one of the above polysaccharides is bonded together and its molecular weight is increased is called cellulose or hemicellulose. Bagasse may contain the above-mentioned cellulose or hemicellulose. Cellulose is composed of multiple glucans bonded together. On the other hand, hemicellulose is composed of two or more polysaccharides bonded together, and examples include glucuronoxylan, arabinoxylan, and glucomannan.

[0030] The components of acid-insoluble substances can be evaluated based on the components measured by dissolving the biomass solid fuel in 72% by mass sulfuric acid, repeatedly filtering and washing to recover the residue that did not dissolve in the sulfuric acid, and then subjecting the residue to pyrolysis GC-MS. Specifically, the components of acid-insoluble substances are evaluated using the peak area of ​​the peaks detected by pyrolysis GC-MS measurement. Pyrolysis GC-MS can be performed by introducing the gas obtained by pyrolysis of the recovered residue in a furnace set to 600°C under a helium gas atmosphere into the GC-MS. The amount of detected components is slightly affected by the instrument conditions if the peak area is directly compared, so from the viewpoint of improving accuracy, it is preferable to determine the amount (relative concentration) based on the peak area of ​​acacia biomass molded body (hereinafter also referred to as "acacia WP").

[0031] Therefore, the relative concentration of the components detected per unit mass in the bagasse char residue B can be expressed by the following formula (1) as follows: Relative concentration = (Peak area of ​​the component detected by pyrolysis GC-MS / Mass of residue B introduced into the heating furnace) / (Peak area of ​​the component detected by pyrolysis GC-MS of acacia WP / Mass of residue A introduced into the heating furnace) (1)

[0032] The above-mentioned biomass solid fuel may contain components insoluble in sulfuric acid (acid-insoluble substances), and the inclusion of such components further suppresses pulverization during manufacturing. The sulfuric acid-insoluble components may be those which produce specific gaseous components when heated. Examples of such specific gaseous components include pentatricont-17-ene and 4-ethylphenol. Note that pentatricont-17-ene is not found in coniferous trees, nor is it observed in the thermal decomposition gases of coniferous trees.

[0033] When a biomass molded body made of acacia is dissolved in 72% by mass sulfuric acid, and the residue A remaining undissolved is heated in a furnace under conditions of a helium gas atmosphere and 600°C, the amount of Pentatricont-17-ene detected per unit mass of residue A in the gas generated is defined as detection amount A. When the biomass solid fuel of this disclosure is dissolved in 72% by mass sulfuric acid, and the residue B remaining undissolved is heated in a furnace under conditions of a helium gas atmosphere and 600°C, the amount of Pentatricont-17-ene detected per unit mass of residue B in the gas generated is defined as detection amount B. In this case, detection amount B may be 0.1 to 0.8 times detection amount A. That is, the relative concentration of Pentatricont-17-ene calculated by replacing "components detected by pyrolysis GC-MS" in the above formula (1) with "Pentatriacont-17-ene detected by pyrolysis GC-MS" may be 0.1 to 0.8. From the viewpoint of suppressing the pulverization of biomass solid fuel, the relative concentration of Pentatriacont-17-ene may be 0.1 to 0.7, 0.1 to 0.6, or 0.2 to 0.6.

[0034] The acetone extract of the biomass solid fuel obtained based on ISO 14453:2014 "Pulp - Measurement of acetone-soluble substances" contains 2,6-Dimethoxyphenol, and the 2,6-Dimethoxyphenol content may be 20 to 124 mg / kg relative to the mass of the biomass solid fuel in an oven-dried state. From the viewpoint of suppressing the pulverization of the biomass solid fuel, the 2,6-Dimethoxyphenol content may be 25 to 120 mg / kg or 30 to 110 mg / kg relative to the mass of the biomass solid fuel in an oven-dried state. Since 2,6-Dimethoxyphenol is a component not found in coniferous trees, biomass solid fuel containing 2,6-Dimethoxyphenol within the above range can suppress pulverization.

[0035] The GC-MS of the pyrolysis of constituent sugars and acid-insoluble substances in biomass solid fuel, and the GC-MS of acetone extracts may be measured directly in the biomass solid fuel using the method described above, or they may be measured for each of two or more types of biomass chars and calculated by weighted average based on the following formula (2). Note that the following formula (2) is applicable to biomass solid fuel containing two types of biomass chars, biomass char A and biomass char B. (Physical properties of biomass solid fuel) = (Measured value in biomass char A) × (1 - Content of biomass char B / 100) + (Measured value in biomass char B) × (Content of biomass char B) / 100 (2)

[0036] The two or more biomass chars in the biomass solid fuel include biomass char A and biomass char B, wherein when the total amount of biomass char A and biomass char B in a completely dry state is taken as 100% by mass, the content of biomass char A is 5 to 95% by mass and the content of biomass char B is 5 to 95% by mass. Biomass char A may contain 0.5 to 1.2% by mass of mannose, 2.0 to 4.5% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 55.0% by mass of glucose as constituent sugars, and biomass char B may contain 7.0 to 10.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.0% by mass of glucose as constituent sugars. Biomass solid fuels containing two or more types of biomass char can further suppress spontaneous combustion during storage.

[0037] Biomass char A may be from a broadleaf tree, for example, acacia. Biomass char B may be from a conifer, for example. Acacia, being a broadleaf tree, has a fast growth rate, which can reduce the cost of producing biomass solid fuel.

[0038] When the total amount of biomass char A and biomass char B in their completely dry state is taken as 100% by mass, the content of biomass char A may be 10-90% by mass, 20-80% by mass, or 25-75% by mass, and the content of biomass char B may be 10-90% by mass, 20-80% by mass, or 25-75% by mass. By having the content of biomass char A and biomass char B within the above ranges, the balance of oxidation, heat storage, and heat release of the biomass solid fuel is stabilized and the maximum temperature reached is reduced, thereby further suppressing spontaneous combustion of the biomass solid fuel during storage.

[0039] The mannose content in biomass char A as a constituent sugar may be 0.6 to 1.1% by mass, or 0.7 to 1.0% by mass. The xylose content in biomass char A as a constituent sugar may be 2.5 to 4.3% by mass, or 3.0 to 4.0% by mass. The arabinose content in biomass char A as a constituent sugar may be 0.5% by mass or less. The glucose content in biomass char A as a constituent sugar may be 45.0 to 55.0% by mass, or 50.0 to 55.0% by mass. The galactose content in biomass char A as a constituent sugar may be 1.0% by mass or less, or 0.5% by mass or less. By ensuring that the content of mannose, xylose, arabinose, glucose, and galactose, which are constituent sugars in biomass char A, is within the above range, it is possible to further suppress spontaneous combustion during storage of biomass solid fuel while also suppressing pulverization of the biomass solid fuel.

[0040] The mannose content in biomass char B as a constituent sugar may be 8.0 to 9.5% by mass, or 8.5 to 9.0% by mass. The xylose content in biomass char B as a constituent sugar may be 2.7 to 3.7% by mass, or 2.8 to 3.4% by mass. The arabinose content in biomass char B as a constituent sugar may be 0.5% by mass or less. The glucose content in biomass char B as a constituent sugar may be 42.0 to 50.0% by mass, or 45.0 to 49.0% by mass. The galactose content in biomass char B as a constituent sugar may be 0.5 to 2.0% by mass, or 1.5 to 1.8% by mass. By ensuring that the content of mannose, xylose, arabinose, glucose, and galactose, which are constituent sugars in biomass char B, is within the above range, it is possible to further suppress spontaneous combustion during storage of biomass solid fuel while also suppressing pulverization of the biomass solid fuel.

[0041] The sugar content of biomass char A and biomass char B can be measured using the same measurement method as described above for biomass solid fuels.

[0042] The maximum temperature reached in the wire basket test of biomass char A may be 195-220°C, 197-210°C, or 198-205°C, and the maximum temperature reached in the wire basket test of biomass char B may be 100°C or more but less than 195°C, 100-190°C, 100-170°C, 100-160°C, 130-190°C, 130-170°C, or 130-160°C. By having the maximum temperatures reached in the wire basket tests of biomass char A and biomass char B within the above ranges, the maximum temperature reached during storage of the biomass solid fuel is reduced, and spontaneous combustion during storage of the biomass solid fuel can be further suppressed.

[0043] In biomass char A, the relative concentration of Pentatriacont-17-ene calculated by formula (1) above may be 0.1 to 1.0, 0.3 to 0.9, or 0.4 to 0.8. In biomass char B, the relative concentration of Pentatriacont-17-ene calculated by formula (1) above may be 1.0% by mass or less, or 0.5% by mass or less. By keeping the relative concentration of Pentatriacont-17-ene calculated by formula (1) above within the above range in biomass char A and biomass char B, the pulverization of the biomass solid fuel can be suppressed.

[0044] The acetone extract of biomass char A obtained based on ISO 14453:2014 "Pulp - Measurement of acetone-soluble substances" contains 2,6-Dimethoxyphenol, and the 2,6-Dimethoxyphenol content may be 50 to 200 mg / kg, 70 to 170 mg / kg, or 90 to 150 mg / kg relative to the mass of biomass char A in its oven-dried state. The acetone extract of biomass char B obtained based on ISO 14453:2014 "Pulp - Measurement of acetone-soluble substances" contains 2,6-Dimethoxyphenol, and the 2,6-Dimethoxyphenol content may be 50 mg / kg or less, 30 mg / kg or less, or 10 mg / kg or less, or 0 mg / kg relative to the mass of biomass char B in its oven-dried state. By having the acetone extracts of biomass char A and biomass char B within the above ranges, the pulverization of biomass solid fuel can be suppressed.

[0045] Biomass char A, biomass char B, and biomass solid fuel have a bulk density of 500-900 kg / m³ according to JIS Z 8807:2012. ３ , 550-800kg / m ３ , or 600-700 kg / m ３ That's fine.

[0046] The moisture content of biomass char A may be 2.0 to 7.0% by mass, 2.5 to 6.5% by mass, or 3.0 to 6.0% by mass. The moisture content of biomass char B may be 4.0 to 9.0% by mass, 4.5 to 8.5% by mass, or 5.0 to 8.0% by mass. The moisture content of the biomass solid fuel may be 4.0 to 8.0% by mass. Within these ranges, a solid fuel with suppressed dust generation and excellent ignition properties can be obtained.

[0047] The ash content in biomass carbide A may be 0.1 to 2.0% by mass, or 0.5 to 1.0% by mass in the absolutely dry state. The ash content in biomass carbide B may be 0.5 to 2.5% by mass, or 1.0 to 2.0% by mass in the absolutely dry state. By the ash content in biomass carbide A and biomass carbide B being within the above ranges, the amount of ash in the biomass solid fuel can be reduced, and fouling can be suppressed. Fouling means that molten or vaporized low melting point ash adheres to a heat transfer tube or a heat exchanger to form an ash adhesion layer. The ash content of the biomass solid fuel may be 0.5 to 2.0% by mass, 0.8 to 1.5% by mass, or 0.8 to 1.4% by mass in the absolutely dry state. The moisture content and the ash content can be measured in accordance with JIS M 8812:2006.

[0048] In the ash composition of biomass carbide A and biomass carbide B, SiO ２ , Fe ２ O ３ , Al ２ O ３ , CaO, MgO, SO ３ , P ２ O ５ , TiO ２ , Na ２ O, K ２ , V ２ O ５ , NiO ２ , and may contain at least one selected from the group consisting of MnO. The content of each component in the ash composition can be determined by the method described in the examples.

[0049] The fuel ratio (fixed carbon / volatile matter) in biomass char A, biomass char B, and biomass solid fuel may be 0.10 to 1.0 or 0.20 to 0.40. Having the fuel ratio within this range further improves the combustibility when the biomass solid fuel is ignited and burned. The fixed carbon and volatile matter of biomass char A, biomass char B, and biomass solid fuel can be measured in accordance with JIS M 8812:2006. The fixed carbon in biomass char A, biomass char B, and biomass solid fuel may be 10.0 to 30.0% by mass or 15.0 to 25.0% by mass. The volatile matter in biomass char A, biomass char B, and biomass solid fuel may be 60.0 to 80.0% by mass or 65.0 to 75.0% by mass. By keeping the volatile and fixed carbon content within the above range, the combustibility of the biomass solid fuel can be further improved when it is ignited and burned.

[0050] The higher heating values ​​of biomass char A, biomass char B, and biomass solid fuel may be 15,000 to 30,000 kJ / kg, 17,000 to 28,000 kJ / kg, or 20,000 to 25,000 kJ / kg in a completely dry state. Having the higher heating value in a completely dry state within the above range can further improve the combustibility of the biomass solid fuel. The higher heating value in a completely dry state can be measured in accordance with JIS M 8814:2003.

[0051] The fuel ratio in the biomass solid fuel may be 0.20 to 0.40, 0.25 to 0.30, or 0.26 to 0.27. The fixed carbon content in the biomass solid fuel may be 15.0 to 25.0 mass%, 19.0 to 21.0 mass%, or 19.1 to 20.1 mass%. The volatile content in the biomass solid fuel may be 65.0 to 75.0 mass%, 70.0 to 74.0 mass%, or 72.2 to 73.3 mass%. The higher heating value in the biomass solid fuel in a completely dry state may be 20,000 to 25,000 kJ / kg, 21,000 to 23,000 kJ / kg, or 21,800 to 22,050 kJ / kg.

[0052] The biomass solid fuel may have a volatile content of 60.0 to 80.0 mass%, fixed carbon of 10.0 to 30.0 mass%, a fuel ratio of 0.10 to 1.0, a higher heating value of 15,000 to 30,000 kJ / kg in a dry state, and an ash content of 0.5 to 2.0 mass% on a dry basis. Alternatively, the biomass solid fuel may have a volatile content of 72.2 to 73.3 mass%, fixed carbon of 19.0 to 20.1 mass%, a fuel ratio of 0.26 to 0.27, a higher heating value of 21,800 to 22,050 kJ / kg in a dry state, and an ash content of 0.8 to 1.5 mass% on a dry basis.

[0053] The true specific gravity of biomass char A, biomass char B, and biomass solid fuel is 1.0–2.0 g / cm³. ３ , 1.2-1.8g / cm ３ , or 1.3 to 1.7 g / cm³ ３ This may also be the case. True specific gravity can be measured, for example, using an ultrapycnometer.

[0054] The BET specific surface area of ​​biomass char A, biomass char B, and biomass solid fuel is 0.10 to 0.60 m². ２ / g, or 0.20-0.50m ２ It may also be / g. The BET specific surface area can be measured, for example, by a constant volume method using nitrogen gas adsorption with a specific surface area / pore size analyzer.

[0055] The pore volume of biomass char A, biomass char B, and biomass solid fuel may be 0.05 to 0.50 mL / g, 0.10 to 0.40 mL / g, or 0.20 to 0.30 mL / g. The pore volume can be measured, for example, by a mercury injection method using a fully automated pore distribution analyzer.

[0056] The specific surface area of ​​biomass char A, biomass char B, and biomass solid fuel is 15.0 to 50.0 m². ２ / g, 20.0-40.0m ２ / g, or 20.0-35.0m ２ It may also be / g. The specific surface area can be measured, for example, by the mercury injection method using a fully automated pore size analyzer.

[0057] The median diameters of biomass char A, biomass char B, and biomass solid fuel may be 1.00 to 6.00 μm, 1.50 to 4.00 μm, or 1.50 to 3.50 μm. Having median diameters within these ranges allows for sufficient mixing of biomass char A and biomass char B, enabling sufficient co-firing of biomass char A and biomass char B in the biomass solid fuel. The median diameter can be measured, for example, by a mercury injection method using a fully automated pore size analyzer.

[0058] The BET specific surface area of ​​biomass solid fuels is 0.20 to 0.50 m². ２ / g, 0.25-0.40m ２ / g, or 0.30-0.38m ２ It may be / g. The pore volume in biomass solid fuel may be 0.20 to 0.30 mL / g, 0.24 to 0.29 mL / g, or 0.26 to 0.28 mL / g. The specific surface area in biomass solid fuel may be 20.0 to 35.0 m². ２ / g, 21.0-27.0m ２ / g, or 23.6-24.8m ２ It may be / g. The median diameter in biomass solid fuel may be 1.50 to 3.50 μm, 1.75 to 3.30 μm, or 2.06 to 3.20 μm.

[0059] Biomass solid fuels have a BET specific surface area of ​​0.10 to 0.60 m². ２ 0.05 to 0.50 mL / g, pore volume 0.05 to 0.50 mL / g, specific surface area 15.0 to 50.0 m² ２ The density may be 1.00 to 6.00 μm / g, and the median diameter may be 1.00 to 6.00 μm. Furthermore, the biomass solid fuel may have a BET specific surface area of ​​0.32 to 0.37 m². ２ / g, pore volume of 0.26–0.28 mL / g, specific surface area of ​​23.6–24.8 m² ２ The concentration may be / g, and the median diameter may be 2.06 to 3.20 μm.

[0060] Biomass char A may have a chemical oxygen demand (COD) of 500 ppm or less, 400 ppm or less, or 300 ppm or less. Biomass char B may have a COD of 1500 ppm or less, 1200 ppm or less, or 1000 ppm or less. The COD of biomass char A and biomass char B may be 50 ppm or more, or 100 ppm or more. An example of the COD range for biomass char A may be 50 to 500 ppm, 50 to 400 ppm, or 100 to 300 ppm. An example of the COD range for biomass char B may be 50 to 1500 ppm, 100 to 1200 ppm, or 100 to 1000 ppm. Having the COD within this range allows for a sufficient reduction in the environmental burden of wastewater during the production of biomass solid fuel.

[0061] The COD of biomass solid fuel may be 295 to 800 ppm or 300 to 700 ppm. Here, the COD of the immersion water when biomass char A, biomass char B, and biomass solid fuel are immersed in water refers to the COD value of the immersion water prepared at room temperature under the following conditions, in accordance with the method for testing metals, etc. contained in industrial waste as stipulated in the Environment Agency Notification No. 13 (i) of 1973: Sample:Water = 1:10 (mass ratio) Shaking method: 200 times / min in the horizontal direction Elution time: 6 hours The COD value of the immersion water can be measured in accordance with JIS K 0102:2016-17 "Oxygen consumption by potassium permanganate at 100°C". Room temperature is, for example, 20°C. Room temperature may be 15 to 25°C or 20 to 25°C.

[0062] The chlorine content in biomass char A may be 0.01 to 0.04 mass%, or 0.02 to 0.03 mass%. The chlorine content in biomass char B may be 0.001 to 0.005 mass%, or 0.002 to 0.004 mass%. The chlorine content in biomass solid fuel may be 0.008 to 0.04 mass%, 0.01 to 0.04 mass%, or 0.02 to 0.03 mass%. The chlorine content can be measured by elemental analysis based on JIS M 8813:2006.

[0063] The shapes of biomass char A, biomass char B, and biomass solid fuel may be cylindrical (pellet-shaped). The diameter may be 6.0 to 10.0 mm, 6.0 to 8.5 mm, or 7.0 to 8.5 mm. The length of the central axis may be 40 mm or less, or 30 mm or less. The length of the central axis may also be 15 mm or more. By having the sizes of biomass char A, biomass char B, and biomass solid fuel within this range, the manufacturing efficiency and handling of biomass char A, biomass char B, and biomass solid fuel can be improved. Note that the shapes of biomass char A, biomass char B, and biomass solid fuel are not limited to cylindrical shapes.

[0064] The volumes of biomass char A, biomass char B, and biomass solid fuel are 1000 to 2500 mm³. ３ , 1200~2000mm ３ This may also be the case. By having the volumes of biomass char A, biomass char B, and biomass solid fuel within this range, the production efficiency and handling of biomass char A, biomass char B, and biomass solid fuel can be improved.

[0065] Biomass char A, biomass char B, and biomass solid fuel do not necessarily need to be molded into a specific shape, and may be in an unformed state such as powder, chips, or flakes.

[0066] When biomass char A, biomass char B, and biomass solid fuel are molded, the mechanical durability (DU) of biomass char A, biomass char B, and biomass solid fuel can be determined in accordance with the American agricultural industry standard ASAE S 269.4 and the German industrial standard DIN EN 15210-1. The DU value may be 90.0 or higher, or 95.0 or higher. Alternatively, the DU value may be 100 or lower. Having a DU within this range allows for sufficiently high handling of biomass char A, biomass char B, and biomass solid fuel. Furthermore, biomass char A, biomass char B, and biomass solid fuel become moderately hard, further suppressing pulverization. An example of the DU range is 90.0 to 100, or 95.0 to 100.

[0067] When biomass char A is molded, the pulverability index (HGI) of biomass char A, based on JIS M 8801:2008, may be 60 or less, or 50 or less. Alternatively, the HGI may be 20 or more, or 25 or more. For example, the HGI may be between 20 and 60, 20 and 50, or 25 and 50. By having the HGI within the above range, biomass char A becomes moderately hard, improving its handling properties. Furthermore, the moisture content of biomass char A after being immersed in water and brought to equilibrium may be 15 to 65% by mass, 15 to 60% by mass, or 15 to 30% by mass.

[0068] If biomass char A and biomass char B have a shape, the grinding work index (BMI2) of biomass char A and biomass char B may be 50.0 to 95.0, 55.0 to 80.0, 60.0 to 85.0, or 70.0 to 80.0. In this disclosure, BMI2 is defined as the ratio of the mass under a sieve with a mesh size of 150 μm to the total mass under a sieve with a mesh size of 1000 μm of a sample that has been ground for 20 minutes according to the procedure based on JIS M 4002:2000 "Test method for grinding work index".

[0069] The physical properties of the biomass solid fuel described above may be obtained by directly measuring the biomass solid fuel using the method described above, or by measuring the values ​​of biomass char A and biomass char B separately and calculating the weighted average based on the following formula (2): (Physical properties of biomass solid fuel) = (Measured value in biomass char A) × (1 - Biomass char content / 100) + (Measured value in biomass char B) × (Biomass char content / 100) (2)

[0070] [Method for producing solid fuel] A method for producing biomass solid fuel according to one embodiment includes a step of mixing two or more types of biomass char to obtain a mixture, wherein the mixture contains 1.3 to 8.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.7% by mass of glucose as constituent sugars. The biomass solid fuel obtained in this way can suppress spontaneous combustion during storage.

[0071] The mixture in the method for producing biomass solid fuel comprises biomass char A and biomass char B, wherein when the total amount of biomass char A and biomass char B in an oven-dry state is taken as 100% by mass, the content of biomass char A is 5 to 95% by mass, and the content of biomass char B is 5 to 95% by mass. Biomass char A may contain 0.5 to 1.2% by mass of mannose, 2.0 to 4.5% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 55.0% by mass of glucose as constituent sugars, and biomass char B may contain 7.0 to 10.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.0% by mass of glucose as constituent sugars. The biomass solid fuel obtained in this way can further suppress spontaneous combustion during storage.

[0072] The above explanation can be applied directly to biomass solid fuel, biomass char, biomass char A, and biomass char B.

[0073] In the process of obtaining the mixture, the method of mixing two or more types of biomass char is not particularly limited and can be carried out by known methods. For example, biomass char A and biomass char B, measured in a predetermined mass ratio, can be mixed using a mixer or the like. By performing the step of mixing biomass char A and biomass char B, the content of biomass char A and B in the biomass solid fuel can be easily adjusted.

[0074] The mixture may be used directly as a biomass solid fuel. Using the mixture directly as a biomass solid fuel can shorten the time required for its production. Alternatively, a molding process may be performed after the process of obtaining the mixture. Performing the molding process can improve the handling properties of the biomass solid fuel.

[0075] [Method for firing solid fuel] A method for firing biomass solid fuel according to one embodiment includes a step of firing the biomass solid fuel described above. The biomass solid fuel described above can suppress spontaneous combustion during storage.

[0076] In the calcination process, the method of calcining the biomass solid fuel is not particularly limited and can be carried out by known methods. For example, it can be calcined in coal combustion equipment such as a boiler.

[0077] This disclosure includes several embodiments: [1] A biomass solid fuel comprising two or more biomass chars, wherein the content of mannose as constituent sugars is 1.3 to 8.0% by mass, the content of xylose is 2.5 to 3.8% by mass, the content of arabinose is 1.0% by mass or less, and the content of glucose is 40.0 to 52.7% by mass. [2] The biomass solid fuel according to [1], wherein the maximum temperature reached as measured by a wire basket test is less than 200°C. [3] The biomass solid fuel according to [1] or [2], wherein the acetone extract according to ISO 14453:2014 contains 2,6-Dimethoxyphenol, and the content of 2,6-Dimethoxyphenol is 20 to 124 mg / kg relative to the mass of the biomass solid fuel in an oven-dry state. [4] A biomass solid fuel according to any one of [1] to [3], wherein when a biomass molded body made of acacia is dissolved in 72% by mass sulfuric acid, and the residue A remaining undissolved is heated in a furnace under the conditions of a helium gas atmosphere and 600°C, the amount of Pentatricont-17-ene detected per unit mass of residue A in the gas generated is defined as detection amount A, and when the biomass solid fuel is dissolved in 72% by mass sulfuric acid, and the residue B remaining undissolved is heated in a furnace under the conditions of a helium gas atmosphere and 600°C, the amount of Pentatricont-17-ene detected per unit mass of residue B in the gas generated is defined as detection amount B, the amount of detection amount B is 0.1 to 0.8 times the amount of detection amount A. [5] A biomass solid fuel according to any one of [1] to [4], wherein the two or more types of biomass chars include at least two types of biomass chars whose maximum temperatures measured in a wire basket test are different from each other. [6] BET specific surface area is 0.32 to 0.37 m ２ / g, pore volume of 0.26–0.28 mL / g, specific surface area of ​​23.6–24.8 m² ２A biomass solid fuel according to any one of [1] to [5], wherein the mass is 2.06 to 3.20 μm. [7] A biomass solid fuel according to any one of [1] to [6], wherein the volatile content is 72.2 to 73.3 mass%, the fixed carbon is 19.0 to 20.1 mass%, the fuel ratio is 0.26 to 0.27, the higher heating value is 21800 to 22050 kJ / kg in an oven-dry state, and the ash content is 0.8 to 1.5 mass% on an oven-dry basis. [8] The two or more biomass chars comprises biomass char A and biomass char B, wherein when the total amount of biomass char A and biomass char B in an oven-dried state is taken as 100% by mass, the content of biomass char A is 5 to 95% by mass, and the content of biomass char B is 5 to 95% by mass, and the biomass char A contains 0.5 to 1.2% by mass of mannose, 2.0 to 4.5% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 55.0% by mass of glucose as constituent sugars. The biomass solid fuel according to any one of [1] to [7], wherein the biomass char B contains 7.0 to 10.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.0% by mass of glucose as constituent sugars. [9] A method for firing a biomass solid fuel, comprising the step of firing the biomass solid fuel according to any one of [1] to [8] above.

[10] A method for producing a biomass solid fuel, comprising the step of mixing two or more biomass chars to obtain a mixture, wherein the mixture contains 1.3 to 8.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.7% by mass of glucose as constituent sugars.

[11] The mixture comprises biomass char A and biomass char B, wherein when the total amount of biomass char A and biomass char B in an oven-dried state is taken as 100% by mass, the content of biomass char A is 5 to 95% by mass, and the content of biomass char B is 5 to 95% by mass, and the biomass char A contains 0.5 to 1.2% by mass of mannose, 2.0 to 4.5% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 55.0% by mass of glucose as constituent sugars. The method for producing a biomass solid fuel according to

[10] , wherein the biomass char B contains 7.0 to 10.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.0% by mass of glucose as constituent sugars.

[0078] The contents of this disclosure will be explained in more detail below with reference to examples and comparative examples. However, this disclosure is not limited to the examples described below.

[0079] (Comparative Example 1) The acacia prepared as raw material was crushed and then pulverized. A molding process was carried out to form the acacia that had been pulverized to 3000 μm or less. In the molding process, the pulverized acacia was uniaxially compressed to obtain a cylindrical acacia molded body (hereinafter referred to as "acacia WP") with a diameter (pellet diameter) of 8.3 mm and a length of 25 mm. Notwithstanding the above, WP was obtained using only the raw biomass without adding a binder to the raw biomass. 4 kg of the obtained acacia WP was placed into a batch-type electric small rotary kiln (manufactured by Takasago Kogyo Co., Ltd.) having a heating chamber with an inner diameter of 600 mm, and heated to 250°C at a heating rate of 2°C / min. After reaching 250°C, it was immediately air-cooled to cool the inside of the rotary kiln to room temperature and acacia char was obtained. The obtained acacia char was designated as biomass char A. The yield was calculated from the mass of acacia WP and the mass of the obtained biomass char A. As a result, the yield was 84.2% by mass.

[0080] [Measurement of pulverization rate] The entire amount of biomass char A found in the rotary kiln was sieved through a 3.35 mm mesh sieve, and the pulverization rate was calculated as the mass ratio of the material below the sieve to the total mass. The sieve was used according to the procedure in accordance with JIS M 8801:2008. As a result, the pulverization rate was 1.7% by mass.

[0081] (Comparative Example 2) Coniferous tree char was obtained using the same procedure as in Comparative Example 1, except that coniferous trees were used as raw materials. The obtained coniferous tree char was designated as Biomass Charcoal B. The coniferous trees used were a mixture of 30% by mass of spruce, 45% by mass of pine, and 25% by mass of fir, which was crushed in a pulverizer. The yield and pulverization rate were calculated using the same procedure as in Comparative Example 1. As a result, the yield was 88.7% by mass and the pulverization rate was 5.3% by mass.

[0082] <Physical Property Evaluation> [Measurement of Chemical Oxygen Demand (COD)] For Comparative Example 1 and Comparative Example 2, the COD of the immersion water samples was measured using a method compliant with JIS K 0102:2016-17 "Oxygen Consumption by Potassium Permanganate at 100°C". The immersion water samples for COD measurement were prepared in accordance with the method for testing metals, etc., contained in industrial waste as specified in the Environmental Agency Notification No. 13 (i) of 1973. Ten times the amount of water by mass was added to acacia char or coniferous tree char, and the mixture was shaken horizontally at a rate of 200 times per minute for 6 hours at room temperature. The results are shown in Table 1.

[0083] [Measurement of Mechanical Durability (DU)] For Comparative Examples 1 and 2, DU was measured according to the following formula (3) in accordance with the American Agricultural Standard ASAE S 269.4 and the German Industrial Standard DIN EN 15210-1. In formula (3), m0 is the mass of the sample before rotation, and m1 is the mass of the sieved sample after rotation. A sieve with a mesh size of 3.15 mm was used. The results are shown in Table 1. DU = (m1 / m0) × 100 (3)

[0084] [Measurement of True Specific Gravity] For Comparative Examples 1 and 2, the true specific gravity was measured using an ultrapycnometer (Ultrapyc5000, manufactured by Quantachrome.co) by the He gas displacement method. The measurement was performed on biomass char A and B in their pellet form without crushing. The results are shown in Table 1.

[0085] [Measurement of BET specific surface area] For Comparative Example 1 and Comparative Example 2, the BET specific surface area was measured using the nitrogen gas adsorption method at constant volume with a specific surface area and pore size analyzer QUADRASORB EVO (manufactured by Quantachrome.co). The measurement was performed on biomass char A and B in their pellet form without crushing. The results are shown in Table 1.

[0086] [Measurement of pore volume, specific surface area, and median diameter] For Comparative Example 1 and Comparative Example 2, the pore volume was determined as the cumulative volume of pores in the sample by mercury injection using a fully automated pore distribution analyzer (PoreMaster 60-GT, manufactured by QuantaChrome Co.). The specific surface area and median diameter were also determined by mercury injection. The results are shown in Table 1.

[0087] [Measurement of bulk density] The bulk density of Comparative Example 1 and Comparative Example 2 was determined based on JIS Z 8807:2012. The results are shown in Table 1.

[0088] [Measurement of Industrial Analysis Values] For Comparative Example 1 and Comparative Example 2, moisture content, ash content, fixed carbon, and volatile matter were determined in accordance with JIS M 8812:2006. The fuel ratio (fixed carbon / volatile matter) was calculated from the determined fixed carbon and volatile matter. The results are shown in Table 1. In Table 1, values ​​with (-ad) indicate measurement results under normal atmospheric conditions, and values ​​with (-dry) indicate measurement results under completely dry conditions.

[0089] [Measurement of Higher Heating Value] For Comparative Example 1 and Comparative Example 2, the higher heating value was measured in accordance with JIS M 8814:2003. The results are shown in Table 1. The higher heating value was determined under both normal atmospheric conditions and in an extremely dry state.

[0090] [Measurement of Grindability Index (HGI)] For Comparative Example 1, the HGI was measured in accordance with JIS M 8801. The results are shown in Table 1.

[0091] [Measurement of Grinding Work Index (BMI2)] Biomass char materials A and B from Comparative Example 1 and Comparative Example 2 were ground using a ball mill for 20 minutes. The ball mill conforming to JIS M 4002:2000 was used, and standard grade ball bearings specified in JIS B 1501:2009 (43 pieces of 36.5 mm diameter, 67 pieces of 30.2 mm diameter, 10 pieces of 24.4 mm diameter, 71 pieces of 19.1 mm diameter, and 94 pieces of 15.9 mm diameter) were housed in a cylindrical container with an inner diameter of 305 mm and an axial length of 305 mm, and rotated at a speed of 70 rpm. After grinding, the material was sieved using a sieve with a mesh size of 1000 μm, and the material below the sieve was further sieved using a sieve with a mesh size of 150 μm. The ratio of the mass under a sieve with a mesh size of 150 μm to the mass under a sieve with a mesh size of 1000 μm was calculated, and this value was defined as BMI2. The results are shown in Table 1.

[0092] [Measurement of Immersion Moisture] For Comparative Example 1, biomass char A was immersed in water for 100 hours to reach equilibrium. After removal from the water, the surface was wiped and the mass was measured. The immersion moisture was calculated from the mass ratio before and after immersion. The results are shown in Table 1.

[0093] [Measurement of Chlorine Content] The chlorine content of Comparative Example 1 and Comparative Example 2 was measured in accordance with JIS M 8813. The results are shown in Table 1.

[0094] [Measurement of Ash Composition] For Comparative Examples 1 and 2, the ash composition was determined in accordance with ISO 18122:2022 "Solid biofuels - Determination of ash content". Biomass chars A and B were heated to 550°C for 2 hours to produce ash, which was used as the measurement sample. The ash composition of the measurement sample was quantified using the fundamental parameter method with an X-ray fluorescence spectrometer (JSX-1000S, JEOL Ltd.) and calculated as the oxide content. The results are shown in Table 1. Note that the ash composition in Table 1 indicates the content of the components in the ash.

[0095] <Component Analysis of Biomass Carbon A and B> To measure the content of constituent sugars in Biomass Carbon A and B of Comparative Examples 1 and 2, Biomass Carbon A and B were decomposed with acid and constituent sugar analysis was performed by GC-MS. Acid-insoluble components were measured by thermal decomposition GC-MS analysis, in which the residue was heated and decomposed. In the thermal decomposition GC-MS analysis, the thermal decomposition temperature was set to 600°C to detect acid-insoluble organic components. In addition, in each of Biomass Carbon A and B, acetone extracts were analyzed by GC-MS to investigate the resin components that bind the carbon aggregates together. Details of each analysis method are described below.

[0096] [Measurement of Constituent Sugar Content] For Comparative Examples 1 and 2, the content of arabinose, xylose, mannose, glucose, and galactose as constituent sugars of the polysaccharides was measured according to the method of the NREL (National Renewable Energy Laboratory) in the United States (http: / / www.nrel.gov / docs / gen / fy13 / 42618.pdf) as described in Non-Patent Document 2. Specifically, 3 mL of 72% by mass sulfuric acid was added to 0.3 g of the sample, reacted at 30°C for 1 hour, then diluted the sulfuric acid concentration to 4% by mass with water, and autoclaved at 121°C for 1 hour using a glass pressure vessel. After adding ribose as an internal standard to the vessel, the acid-insoluble lignin was filtered. After derivatizing the filtrate using the aldonitrile acetylation method, the content of glucose, xylose, arabinose, galactose, and mannose in the filtrate was measured using GC-MS. While NREL uses HPLC for analysis, Non-Patent Literature 2 uses GC-MS, which is more versatile and has superior selectivity, and GC-MS was also used in this study. Therefore, the measurements were performed after derivatizing the filtrate using the aldonitrile acetylation method.

[0097] To correct for monosaccharide over-decomposition, standard solutions of known concentrations were prepared, sulfuric acid was added to achieve a concentration of 4% by mass, and then the solutions were autoclaved at 121°C for 1 hour. The recovery rate of the standard solutions prepared in this way was used as the polysaccharide conversion factor. The polysaccharide conversion factors were 0.88 for arabinose, 0.88 for xylose, 0.90 for mannose, 0.90 for glucose, and 0.90 for galactose. The content of arabinan, xylan, mannan, glucan, and galactan was determined by multiplying the content of constituent sugars in the obtained biomass chars A and B by the polysaccharide conversion factor. The results are shown in Table 2.

[0098] [Measurement of Acid-Insoluble Substances] Acid-insoluble substances were measured for biomass chars A and B of Comparative Example 1 and Comparative Example 2. Using the same method as described above for [Measurement of Constituent Sugar Content], 3 mL of 72% by mass sulfuric acid was added to 0.3 g of the sample, and after reacting at 30°C for 1 hour, the sulfuric acid concentration was diluted with water to 4% by mass. Then, the sample was autoclaved at 121°C for 1 hour using a glass pressure vessel, and the residue was collected after repeated filtration in a suction filtration bottle and washing with water and boiling water to remove the sulfuric acid.

[0099] The recovered residue was introduced into a heating furnace set to 600°C under a helium atmosphere. The generated gas was then directly introduced into a GC-MS for pyrolysis GC-MS analysis, and the relative concentration was calculated. The conditions for the heating furnace and GC-MS equipment were as follows.

[0100] [Heating Furnace] Equipment: Frontier Labs "EGA / PY-3030D" Heating conditions: 600°C instantaneous heating Atmosphere: He

[0101] [GC-MS] Instrument: Shimadzu Corporation "QP-2010 Ultra" Column: Restek "Rtx5 Amine" Inner diameter: 0.25 mm, Length: 30 m, Film thickness: 0.5 μm Column temperature: 40°C, heating at 10°C / min, 280°C (hold) Inlet temperature: 280°C Interface temperature: 300°C Carrier gas: He, Carrier gas flow rate: 1.8 mL / min Ionization method: Electron ionization (EI) Measurement mass range (m / z): 10-600

[0102] The relative concentration is a value that can be calculated using the following formula (4): Relative concentration = (Peak area detected by pyrolysis GC-MS of each component / Mass of sample placed in the heating furnace) ÷ (Peak area of ​​each component detected by pyrolysis GC-MS of acacia WP / Mass of sample placed in the heating furnace) (4)

[0103] The peak area was calculated by defining the baseline as the peak start position (where the peak rises) and the base end position (where the peak ends). The baseline was defined by connecting these two points, and the area enclosed by the curve passing through this baseline and the peak top was defined as the peak area.

[0104] Table 2 shows the measurement results of the relative concentrations of heptacosan-1-ol and pentatricont-17-ene per sample mass. The relative concentration of heptacosan-1-ol was determined using pentatricont-17-ene from acacia WP as the reference.

[0105] [GC-MS and Pyrolysis Compounds of Acetone Extracts] For biomass chars A and B of Comparative Examples 1 and 2, approximately 10 g of freeze-pulverized samples were used to calculate the acetone extract content of the samples in accordance with "ISO 14453: Pulps - Determination of acetone-solubile matter". Qualitative analysis of the acetone extract components was performed by appropriately diluting a portion of the extract with acetone and then analyzing it using a gas chromatograph-mass spectrometer (GC-MS), identifying the main detected components (peaks). Identification was estimated by comparing the mass spectra and GC retention index of the detected components with libraries such as NIST.

[0106] A portion of the diluted acetone extract was derivatized with a BSTFA derivatization reagent to produce trimethylsilyl (TMS) derivatization. The derivatized main components were then analyzed by GC-MS to identify and perform a simplified quantitative analysis. The simplified quantitative analysis was expressed as a converted concentration relative to vanillin, using vanillin present in all samples as the reference. Specifically, a calibration curve was obtained from the vanillin standard solution and expressed by the following formula (5): Vanillin equivalent concentration (mg / kg) = (peak area of ​​each component / peak area of ​​vanillin standard solution) × vanillin standard solution concentration × acetone extract volume × dilution ratio / mass of biomass chars A and B in a completely dry state. (5)

[0107] Table 2 shows the measured acetone extract (mass%), and the vanillin-equivalent concentrations of catechol, 4-ethylphenol, and 2,6-dimethoxyphenol.

[0108] The instrumental analysis conditions are as follows: Instrument: [GC] Nexus GC-2030 (Shimadzu Corporation) [MS] GCMS-TQ8040NX (Shimadzu Corporation) Column: HP-5MS (Agilent Technologies, inner diameter: 0.25 mm, length: 30 m, film thickness: 0.25 μm) Column temperature: 80°C (hold for 1 min), heating at 5°C / min, 300°C (hold for 25 min) Injection port temperature: 250°C, transfer line temperature: 300°C Carrier gas: He 1.2 mL / min (constant flow rate) Injection method: Split (10:1) Injection volume: 1 μL Ionization method: Electron ionization (EI) Measurement method: SCAN (m / z: 20-500)

[0109] [Preparation of Biomass Solid Fuel] (Comparative Example 3) Biomass solid fuel was obtained by weighing and mixing acacia char from Comparative Example 1 as biomass char A and coniferous tree char from Comparative Example 2 as biomass char B in an oven-dry state, in a mass ratio of biomass char A:biomass char B = 98:2. The mixing method involved weighing the pellets from Comparative Example 1 and Comparative Example 2 and mixing them in a polyethylene bag with a volume of at least 10 times the total volume of the mixture, at a strength that did not cause the mixed biomass solid fuel to pulverize.

[0110] (Example 1) A biomass solid fuel was obtained using the same procedure as in Comparative Example 3, except that the mixture of biomass char A and biomass char B was in a mass ratio of 95:5.

[0111] (Example 2) A biomass solid fuel was obtained using the same procedure as in Comparative Example 3, except that the biomass char A and biomass char B were mixed in a mass ratio of 90:10.

[0112] (Example 3) A biomass solid fuel was obtained using the same procedure as in Comparative Example 3, except that the biomass char A and biomass char B were mixed in a mass ratio of 75:25.

[0113] (Example 4) A biomass solid fuel was obtained using the same procedure as in Comparative Example 3, except that the biomass char A and biomass char B were mixed in a mass ratio of 50:50.

[0114] (Example 5) A biomass solid fuel was obtained using the same procedure as in Comparative Example 3, except that the biomass char A and biomass char B were mixed in a mass ratio of 25:75.

[0115] [Calculation of physical properties in Comparative Example 3 and Examples 1-5] For the biomass solid fuels of Comparative Example 3 and Examples 1-5, the measurement results for COD, true specific gravity, BET specific surface area, pore volume, specific surface area, median diameter, industrial analysis value, higher heating value, ash composition, constituent sugars, thermal decomposition GC-MS of acid-insoluble substances, and GC-MS of acetone extracts were calculated by weight-averaging the measurement results of Comparative Example 1 and Comparative Example 2 based on the following formula (6). The calculation results are shown in Tables 1 and 2. (Physical properties of solid fuel) = (Measured value in biomass char A) × (1 - Content of biomass char B / 100) + (Measured value in biomass char B) × (Content of biomass char B) / 100 (6)

[0116] For the ash composition of the biomass solid fuels in Comparative Example 3 and Examples 1 to 5, first, the biomass char content in the ash of the biomass solid fuel was calculated on a weighted average basis based on the following formula (7), using the oven-dry standard. The calculated (biomass char content on a weighted basis) was used as (biomass char content) in formula (6) above, and the ash composition of Comparative Examples 1 and 2 was calculated by weight averaging. The results are shown in Table 1. (Biomass char content on a weighted basis) = (Biomass char content) × (Amount of ash of biomass char in an oven-dry state) / [(Biomass char content) × (Amount of ash of biomass char in an oven-dry state) + (100 - Biomass char content) × (Amount of ash of biomass char in an oven-dry state)] × 100 (7)

[0117] [Evaluation of Self-Heating Properties (Spontaneous Combustion)] To evaluate the self-heating properties (spontaneous combustion), the maximum temperatures reached in Comparative Examples 1-3 and Examples 1-5 were measured using a wire basket test in accordance with the provisions of the UN recommended test method "Manual of Tests and Criteria 7th edition," 33.4.6 Test N.4: Test Method for self-heating Substances. Figure 1 shows the relationship between the acacia char content in the biomass solid fuel and the maximum temperature reached. In Comparative Examples 1 and 3, heating was stopped when the temperature exceeded 200°C to suppress combustion, and nitrogen gas was blown in.

[0118] Tables 1 and 2 are shown below. In Tables 1 and 2, items for which measurements were not performed are indicated with a "-". In Table 2, "0" for constituent sugars indicates that the value is below the detection limit. In Tables 1 and 2, all physical property values ​​for Comparative Example 1 and Comparative Example 2 are measured values. In Comparative Example 3 and Examples 1 to 5, only the maximum temperature reached is a measured value; all other values ​​are calculated values ​​obtained using formula (6) or formula (7).

[0119]

[0120]

[0121] As shown in Table 2 and Figure 1, the biomass solid fuels of Examples 1 to 5, which were created by mixing two or more types of biomass char and adjusting the content of constituent sugars, showed a lower maximum temperature reached in the wire basket test, demonstrating that spontaneous combustion during storage could be suppressed.

[0122] As shown in Tables 1 and 2 and Figure 1, Comparative Example 3, which mixed 98% by mass of biomass char A and 2% by mass of biomass char B, achieved the same maximum temperature as Comparative Example 1, which used 100% by mass of biomass char A. On the other hand, Example 1, which used 5% by mass of biomass char B, showed a significantly lower maximum temperature. Therefore, it is considered that by mixing two or more types of biomass char and appropriately adjusting the content of constituent sugars, the maximum temperature can be significantly reduced, further suppressing the spontaneous combustion of biomass solid fuel.

[0123] This disclosure provides a biomass solid fuel that suppresses spontaneous combustion during storage, a method for calcining the biomass solid fuel, and a method for producing the biomass solid fuel.

Claims

1. A biomass solid fuel containing two or more types of biomass char, wherein the constituent sugars include mannose content of 1.3 to 8.0% by mass, xylose content of 2.5 to 3.8% by mass, arabinose content of 1.0% by mass or less, and glucose content of 40.0 to 52.7% by mass.

2. The biomass solid fuel according to claim 1, wherein the maximum temperature reached by the wire basket test is less than 200°C.

3. The biomass solid fuel according to claim 1 or 2, wherein the acetone extract according to ISO 14453:2014 contains 2,6-Dimethoxyphenol, and the content of 2,6-Dimethoxyphenol is 20 to 124 mg / kg relative to the mass of the biomass solid fuel in an oven-dried state.

4. When a biomass molded body made of acacia is dissolved in 72% by mass sulfuric acid, and the residue A remaining undissolved is heated in a furnace under conditions of a helium gas atmosphere and 600°C, the amount of Pentatricont-17-ene detected per unit mass of residue A in the gas generated is defined as detection amount A, and when the biomass solid fuel is dissolved in 72% by mass sulfuric acid, and the residue B remaining undissolved is heated in a furnace under conditions of a helium gas atmosphere and 600°C, the amount of Pentatricont-17-ene detected per unit mass of residue B in the gas generated is defined as detection amount B, the detection amount B is 0.1 to 0.8 times the detection amount A, as described in claim 1 or 2.

5. The biomass solid fuel according to claim 1 or 2, wherein the two or more biomass chars include at least two biomass chars whose maximum temperatures, as measured by a wire basket test, are different from each other.

6. BET specific surface area is 0.32 to 0.37 m² ２ / g, pore volume of 0.26–0.28 mL / g, specific surface area of ​​23.6–24.8 m² ２ The biomass solid fuel according to claim 1 or 2, wherein the amount per g and the median diameter are 2.06 to 3.20 μm.

7. The biomass solid fuel according to claim 1 or 2, wherein the volatile content is 72.2 to 73.3% by mass, the fixed carbon content is 19.0 to 20.1% by mass, the fuel ratio is 0.26 to 0.27, the higher heating value is 21,800 to 22,050 kJ / kg in an oven-dry state, and the ash content is 0.8 to 1.5% by mass on an oven-dry basis.

8. The two or more biomass chars mentioned above include biomass char A and biomass char B, wherein when the total amount of biomass char A and biomass char B in an oven-dried state is taken as 100% by mass, the content of biomass char A is 5 to 95% by mass, and the content of biomass char B is 5 to 95% by mass, and the biomass char A contains 0.5 to 1.2% by mass of mannose, 2.0 to 4.5% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 55.0% by mass of glucose as constituent sugars. The biomass solid fuel according to claim 1 or 2, wherein the biomass char B contains 7.0 to 10.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.0% by mass of glucose as constituent sugars.

9. A method for calcining a biomass solid fuel, comprising the step of calcining the biomass solid fuel described in claim 1 or 2.

10. A method for producing a biomass solid fuel, comprising the step of mixing two or more types of biomass carbon to obtain a mixture, wherein the mixture contains 1.3 to 8.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.7% by mass of glucose as constituent sugars.

11. The mixture comprises biomass char A and biomass char B, wherein, when the total amount of biomass char A and biomass char B in an oven-dried state is taken as 100% by mass, the content of biomass char A is 5 to 95% by mass, and the content of biomass char B is 5 to 95% by mass, and the biomass char A contains 0.5 to 1.2% by mass of mannose, 2.0 to 4.5% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 55.0% by mass of glucose as constituent sugars. The method for producing a biomass solid fuel according to claim 10, wherein the biomass char B contains 7.0 to 10.0% by mass of mannose, 2.5 to 3.8% by mass of xylose, 1.0% by mass or less of arabinose, and 40.0 to 52.0% by mass of glucose as constituent sugars.

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