Method for carbonizing biomass material and method for producing biochar from biomass material

Abstract

Provided is a method for carbonizing a biomass material, said method comprising: mixing a biomass material (A) and an oil (B) that contains an unsaturated fatty acid to obtain a mixture; and supplying an oxygen-containing gas to the mixture, causing the mixture to generate heat, and carbonizing the mixture. Also provided is a method for producing biochar, said method comprising: mixing a biomass material (A) and an oil (B) that contains an unsaturated fatty acid to obtain a mixture; and supplying an oxygen-containing gas to the mixture, causing the mixture to generate heat, and carbonizing the mixture the obtain biochar.

Description

Methods for carbonizing biomass materials, and methods for producing biochar from biomass materials.

[0001] This invention relates to a method for carbonizing biomass materials and a method for producing biochar from biomass materials.

[0002] Carbonization is an important technology for converting biomass materials into biochar, which can be used as solid fuel or soil conditioner. Generally, the carbonization method for biomass materials involves two steps: a drying step for the biomass material and a carbonization step for the dried biomass material (thermal decomposition under low-oxygen conditions so that the biomass material does not burn). Since biomass materials have a high moisture content, external heating (energy input) is necessary to carry out the carbonization method for biomass materials. In particular, the energy consumption of the drying step greatly affects the overall carbonization method. For example, livestock manure, a biomass material, generally has a moisture content of over 80%, and it is known that very large amounts of external heating are required to dry it, resulting in high costs.

[0003] For example, Patent Document 1 discloses a method for carbonizing waste containing food waste as a biomass material by pressurizing and heating (150-200°C) in a steam kettle. Patent Document 2 discloses a method for subcritical water splitting treatment of waste such as livestock products using a subcritical water apparatus equipped with a reaction vessel, heating means, and pressurizing means, at a reaction temperature of 130-374°C and a reaction pressure equal to or greater than the saturated water vapor pressure at the reaction temperature. Both methods have the problem of high costs because they require external heating to dry the biomass material with a high moisture content.

[0004] On the other hand, Patent Document 3 discloses a method for carbonizing a biomass material by forcibly supplying oxygen to the inside of a muddy biomass material, thereby generating heat through an oxidation reaction (microbial oxidation reaction) by microorganisms contained in the biomass material, raising the temperature of the biomass material to at least 55°C, and then raising the temperature of the biomass material to 100°C or higher through the biomass material's own self-heating reaction (chemical oxidation reaction).

[0005] Patent Document 4 discloses a method for carbonizing biomass material by placing it in a specific initial environment, generating heat through an oxidation reaction (microbial oxidation reaction) by microorganisms contained in the biomass material, raising the biomass material to a temperature exceeding 80°C, and then placing the biomass material in a specific continuous environment to allow the biomass material to undergo its own self-heating reaction (chemical oxidation reaction), raising the biomass material to a temperature of 150°C or higher. Patent Documents 3 and 4 do not use external heating, which can reduce costs, but they have drawbacks such as requiring more time.

[0006] Patent Document 5 discloses a method for carbonizing biomass material by placing it in a specific initial environment where it is kept warm by external heating, generating heat through an oxidation reaction (microbial oxidation reaction) by microorganisms contained in the biomass material, raising the temperature of the biomass material to over 80-160°C, and then placing the biomass material in a specific continuous environment to allow the biomass material to undergo its own self-heating reaction (chemical oxidation reaction), raising the temperature of the biomass material to over 160°C. Although Patent Document 5 reduces the cost reduction effect because it uses external heating to keep the biomass material warm during the microbial oxidation reaction, it allows for control of the microbial oxidation reaction and further shortens the time required.

[0007] Japanese Patent Publication No. 2001-137806 WO2005 / 077514 (International Open Pamphlet) Japanese Patent Publication No. 2009-249240 Japanese Patent Publication No. 2011-98330 Japanese Patent Publication No. 2019-155272

[0008] Itoh, T., Iwabuchi, K., Maemoku, N., Sasaki, I., Taniguro, K. A new torrefaction system employing spontaneous self-heating of livestock manure under elevated pressure. Waste Management 85, 65-72 (2019).Saludes RB, Iwabuchi K, Kayanuma A, Shiga T, Compositing of dairy cattle manure using a thermophilic-mesophilic sequence. Biosyst Eng 2007;98:198-205. doi:10, 1016 / j.biosystemseng, 2007.07.003.

[0009] Patent documents 3 to 5 all disclose methods for carbonizing biomass materials that can reduce the amount of heating required for the biomass material. However, these methods lacked sufficient reproducibility and reliability. For example, it was observed that the process did not transition from microbial reaction to chemical oxidation reaction, and the temperature did not rise above 70°C. In other words, the methods described in patent documents 3 to 5 lacked sufficient reproducibility and reliability.

[0010] The present invention is based on the circumstances described above and aims to provide a method for carbonizing biomass materials and a method for producing biochar that can be carried out with greater reproducibility and reliability while further reducing external heating and external heating costs.

[0011] As a result of diligent research, the inventors have found that a method for carbonizing biomass material or producing biochar can be obtained, which includes mixing biomass material with oil containing unsaturated fatty acids to obtain a mixture, and supplying oxygen-containing gas to the mixture to generate heat. Furthermore, they have found that such a carbonization method and biochar production method can be performed with greater reproducibility and reliability while further reducing external heating and external heating costs, thus completing the present invention.

[0012] This specification includes the following embodiments. 1. A method for producing biochar, comprising: mixing a biomass material (A) and an oil (B) containing an unsaturated fatty acid to obtain a mixture; and supplying an oxygen-containing gas to the mixture to cause heat generation and carbonization to obtain biochar. 2. The production method according to item 1 above, wherein the biomass material (A) includes at least one selected from the group consisting of food waste, livestock excreta, agricultural waste, fishery waste and forestry waste. 3. The production method according to item 1 or 2 above, wherein the unsaturated fatty acid includes at least one selected from the group consisting of C14 or more and C24 or less unsaturated fatty acids. 4. The production method according to any one of items 1 to 3 above, wherein the unsaturated fatty acid is contained in an amount of 2.0 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the biomass material (excluding water). 5. The production method according to any one of items 1 to 4 above, wherein the unsaturated fatty acid includes a polyunsaturated fatty acid. 6. The production method according to item 5 above, wherein the polyunsaturated fatty acid includes at least one selected from polyunsaturated fatty acids of C14 or more and C24 or less. 7. The production method according to item 5 or 6 above, wherein the polyunsaturated fatty acid is contained in an amount of 1.2 parts by mass or more and 170 parts by mass or less per 100 parts by mass of the biomass material (excluding moisture). 8. The production method according to any one of items 1 to 7 above, wherein the oil (B) containing an unsaturated fatty acid includes at least one selected from the group consisting of vegetable oils, animal fatty oils, and waste oils thereof. 9. The production method according to any one of items 1 to 8 above, wherein the oxygen-containing gas includes at least one selected from the group consisting of air and oxygen. 10. The production method according to any one of items 1 to 9 above, wherein the oxygen-containing gas is supplied to the mixture at a rate of 0.80 gO ２ h －１ kg‑AFS －１ or more and 33.6 gO ２ h －１ kg‑AFS －１ or less, according to any one of items 1 to 9 above. 11. In the mixture, the oxygen-containing gas, converted in terms of oxygen supply amount: at a temperature lower than 70°C, at a pressure of 0.1 MPa or more and less than 1.5 MPa, at a rate of 1.67 gO ２ h －１ kg‑AFS －１ or more and 20.0 gO ２ h －１ kg‑AFS－１ Below, at temperatures between 70°C and 100°C, the pressure is 0.5 MPa or more but less than 1.5 MPa, and the amount is 0.80 gO. ２ h －１ kg-AFS －１ The above is 3.34 gO ２ h －１ kg-AFS －１ Below, when the temperature exceeds 100°C, 0.80 gO is consumed at a pressure of 0.1 MPa or more and less than 1.5 MPa. ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１The following are manufacturing methods according to any one of 1 to 10 above: 12. A method for carbonizing biomass material, comprising: mixing biomass material (A) with oil (B) containing unsaturated fatty acids to obtain a mixture; supplying oxygen-containing gas to the mixture to generate heat and carbonize it. 13. The manufacturing method according to 12 above, wherein the biomass material (A) includes at least one selected from the group consisting of food waste, livestock excrement, agricultural waste, fishery waste and forestry waste. 14. The manufacturing method according to 12 or 13 above, wherein the unsaturated fatty acid includes at least one selected from the group consisting of unsaturated fatty acids with C14 or more and C24 or less. 15. The manufacturing method according to any one of 12 to 14 above, wherein the unsaturated fatty acid is contained in an amount of 2.0 parts by mass or more and 400 parts by mass or less per 100 parts by mass of biomass material (excluding water). 16. The manufacturing method according to any one of 12 to 15 above, wherein the unsaturated fatty acid includes polyunsaturated fatty acids. 17. The method for producing polyunsaturated fatty acids according to 16, wherein the polyunsaturated fatty acid comprises at least one selected from polyunsaturated fatty acids of C14 or higher and C24 or lower. 18. The method for producing polyunsaturated fatty acids according to 16 or 17, wherein the amount of polyunsaturated fatty acids is 1.2 parts by mass or more and 170 parts by mass or less per 100 parts by mass of biomass material (excluding water). 19. The method for producing oil (B) containing unsaturated fatty acids according to any one of 12 to 18, wherein the oil comprises at least one selected from the group consisting of vegetable oil, animal fat oil, and their waste oil. 20. The method for producing oxygen according to any one of 12 to 19, wherein the oxygen-containing gas comprises at least one selected from the group consisting of air and oxygen. 21. The mixture contains an oxygen-containing gas equivalent to 0.80 gO20 in terms of oxygen supply amount. ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ The following is a manufacturing method described in any one of items 12 to 20 above, which is supplied: 22. Add an oxygen-containing gas to the mixture, in terms of oxygen supply amount, at a pressure of 0.1 MPa or more and less than 1.5 MPa at temperatures below 70°C, at a rate of 1.67 gO ２ h －１ kg-AFS －１ Total 20.0 g ２ h－１ kg-AFS －１ Below, at temperatures between 70°C and 100°C, the pressure is 0.5 MPa or more but less than 1.5 MPa, and the amount is 0.80 gO. ２ h －１ kg-AFS －１ The above is 3.34 gO ２ h －１ kg-AFS －１ Below, when the temperature exceeds 100°C, 0.80 gO is consumed at a pressure of 0.1 MPa or more and less than 1.5 MPa. ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ The manufacturing method described in any one of items 12 to 21 above is supplied below.

[0013] The method for carbonizing biomass materials and the method for producing biochar according to the present invention can be carried out more reproducibly and reliably while further reducing external heating and external heating costs.

[0014] Figure 1 shows the configuration of the apparatus used in the example.

[0015] In one aspect of the present invention, a novel method for producing biochar is provided, which includes: mixing a biomass material (A) with an oil (B) containing unsaturated fatty acids to obtain a mixture; and supplying an oxygen-containing gas to the mixture to generate heat and carbonize it to obtain biochar.

[0016] In this specification, biomass material (A) refers to material based on renewable organic resources of biological origin (such as plants and animals), excluding fossil fuels such as petroleum. Biomass material (A) is not particularly limited as long as it can be used in the method for producing biochar, which is the objective of this invention, and in the method for carbonizing biomaterials described later.

[0017] Examples of biomass materials include one or more types of waste selected from food waste, livestock excrement, agricultural waste, fishery waste, and forestry waste. Specifically, examples include food waste such as kitchen waste (food residue), livestock excrement from cattle, pigs, horses, etc. (manure and urine), agricultural waste such as surplus products, sorted and discarded products, and processing by-products (rice bran, etc.), fishery waste such as excess catches and processing waste, and forestry waste such as wood chips, wood waste, and processing waste. These can be used individually or in combination.

[0018] The biomass material may contain water, and is not limited by its water content, as long as it can be used in the biochar production method and the biomaterial carbonization method described later, which are the objectives of this invention. The biomass material may be, for example, muddy or dry, or it may already be composted. For example, biomass materials with a high water content that do not allow oxygen to penetrate easily when left standing and do not easily undergo biochemical reactions by microorganisms; biomass materials that are muddy overall or locally and have poor aeration; dry biomass materials with a low water content (including 0% by mass) that have carbon as a substrate, such as dairy cow manure, wood chips, and brown rice; and already composted biomass materials are also applicable.

[0019] Composted biomass material refers to material that has been composted by the decomposition reaction of organic matter by microorganisms upon contact with oxygen, for example, by raising the temperature to at least 55°C. After composting, such biomass material can be reduced in volume or carbonized by applying the manufacturing method or carbonization method of the present invention. The carbonized material can then be used as carbonized material, for example, or returned to nature by landfill or other means.

[0020] For example, biomass materials such as livestock excrement (feces and urine) and agricultural waste, which have a water content of 80% by mass or more overall, or which have a water content of 80% by mass or more locally, may be muddy. Biomass materials may even be muddy.

[0021] When the biomass material is food waste such as kitchen waste, its moisture content may be, for example, 40% by mass or more for the entire biomass material, or it may be less overall but 40% by mass or more locally. When the biomass material contains a lot of fiber, such as livestock excrement (manure) or agricultural waste mentioned above, it can turn into mud if the overall or local moisture content is 80% by mass or more. On the other hand, if it is kitchen waste that does not contain much fiber, it can turn into mud even if the moisture content is less than 80% by mass, and can usually turn into mud at 40% by mass or more. Such food waste can also be used in the method for producing biochar of the present invention and the method for carbonizing biomaterials described later, as described above.

[0022] "Overall" moisture content refers to the percentage of moisture when it is distributed evenly or relatively evenly throughout the biomass material. On the other hand, "locally" moisture content refers to a biomass material in which, even if the overall moisture content is less than 80% by mass (for example, in the case of livestock excrement) or less than 40% by mass (for example, in the case of food waste such as kitchen garbage), there are parts of the biomass material that are muddy with a moisture content of 80% by mass or more (for example, in the case of livestock excrement) or 40% by mass or more (for example, in the case of food waste such as kitchen garbage).

[0023] The overall moisture content of biomass material can be determined by taking a certain amount of biomass material as a sample and measuring the mass of the sample before and after drying. On the other hand, the local moisture content of biomass material can be determined by taking a small amount of sample locally and measuring the mass of the sample before and after drying. The moisture content of biomass material (A) may be 40% by mass or more and 80% by mass or less, or 50% by mass or more and 70% by mass or less. Biomass material (A) may be livestock excrement, agricultural waste, fishery waste and forestry waste, livestock excrement and agricultural waste, livestock excrement, or livestock manure.

[0024] A mixture containing biomass material (A) and oil containing unsaturated fatty acids (B) may contain other waste. Examples of other waste include plastic materials (such as food dividers, bottle caps, straws, rubber bands, and packaging materials) that are easily disposed of with household food waste, paper products, and wood products (such as chopsticks and toothpicks). Since plastic materials have different heat resistances depending on the type, examples here include plastic materials with a glass transition temperature of 200°C or less, particularly 150°C or less, such as polyethylene naphthalate (glass transition temperature: 120°C), polybutylene terephthalate (75°C), polyethylene terephthalate (75°C), polyphenylene sulfide (90°C), polyether ether ketone (143°C), and polycarbonate (145°C). When these wastes are mixed into the above mixture, they can be reduced in volume or carbonized together with the biomass material, which rises to a temperature of at least 150°C.

[0025] In this specification, oil (B) containing unsaturated fatty acids is a hydrophobic chemical substance derived from animals or plants that undergoes phase separation with water, and is not particularly limited as long as it contains unsaturated fatty acids and can be used in the method for producing biochar for which the present invention aims, and in the method for carbonizing biomaterials described later.

[0026] In this specification, an unsaturated fatty acid is a monovalent carboxylic acid having a carboxyl group in a hydrocarbon chain containing a double bond between two carbon atoms, and is not particularly limited as long as it can be used in the biochar production method and the biomaterial carbonization method described later, which are the objectives of the present invention.

[0027] The unsaturated fatty acids preferably include at least one selected from the group consisting of unsaturated fatty acids with C14 or more and C24 or less, more preferably at least one selected from the group consisting of unsaturated fatty acids with C16 or more and C22 or less, and even more preferably at least one selected from the group consisting of unsaturated fatty acids with C18 or more and C20 or less.

[0028] It is preferable that the biomass material (excluding water) contains unsaturated fatty acids in an amount of 2.0 parts by mass or more and 400 parts by mass per 100 parts by mass, more preferably 5.0 parts by mass or more and 233 parts by mass, even more preferably 10.0 parts by mass or more and 150 parts by mass, and still more preferably 20.0 parts by mass or more and 100 parts by mass. When the biomass material (excluding water) contains unsaturated fatty acids in an amount of 2.0 parts by mass or more and 400 parts by mass per 100 parts by mass, the supply of oxygen to the inside of the biomass material can be made more reliable.

[0029] The unsaturated fatty acids preferably include polyunsaturated fatty acids. More preferably, the polyunsaturated fatty acids include diunsaturated fatty acids or triunsaturated fatty acids, and even more preferably, diunsaturated fatty acids. When the unsaturated fatty acids include polyunsaturated fatty acids, the mixture may generate heat more easily.

[0030] The unsaturated fatty acids preferably include at least one selected from the group consisting of polyunsaturated fatty acids with C14 to C24, more preferably at least one selected from the group consisting of polyunsaturated fatty acids with C16 to C22, and even more preferably at least one selected from the group consisting of polyunsaturated fatty acids with C18 to C20.

[0031] It is preferable that the biomass material (excluding water) contains polyunsaturated fatty acids in an amount of 1.2 parts by mass or more and 170 parts by mass or less per 100 parts by mass of biomass material (excluding water), more preferably 3.0 parts by mass or more and 100 parts by mass or less, even more preferably 6.0 parts by mass or more and 65.0 parts by mass or less, and even more preferably 10.0 parts by mass or more and 45.0 parts by mass or less. When the biomass material (excluding water) contains polyunsaturated fatty acids in an amount of 1.2 parts by mass or more and 170 parts by mass or less per 100 parts by mass of biomass material (excluding water), the supply of oxygen to the inside of the biomass material can be made more reliable.

[0032] Examples of unsaturated fatty acids include monounsaturated fatty acids such as myristoleic acid (C14:1), palmitoleic acid (C16:1), sapienic acid (C16:1), oleic acid (C18:1), elaidic acid (C18:1), vaccenic acid (C18:1), gadoleic acid (C20:1), eicosenoic acid (C20:1), erucic acid (C22:1), and nervonic acid (C24:1); linol Examples include diunsaturated fatty acids such as acid (C18:2), eicosadienoic acid (C20:2), and docosadienoic acid (C22:2); and triunsaturated fatty acids such as linolenic acid (C18:3), pinolenic acid (C18:3), eleostearic acid (C18:3), meadic acid (C20:3), dihomo-γ-linolenic acid (C20:3), and eicosatrienoic acid (C20:3).

[0033] The monounsaturated fatty acids preferably include at least one selected from the group consisting of palmitoleic acid (C16:1), sapienic acid (C16:1), oleic acid (C18:1), elaidic acid (C18:1), vaccenic acid (C18:1), gadoleic acid (C20:1), and eicosenoic acid (C20:1). The diunsaturated fatty acids preferably include linoleic acid (C18:2). The triunsaturated fatty acids preferably include at least one selected from the group consisting of linolenic acid (C18:3), pinolenic acid (C18:3), and eleostearic acid (C18:3).

[0034] The oil (B) containing unsaturated fatty acids preferably includes at least one selected from the group consisting of vegetable oil, animal fat oil, and their waste oil (waste vegetable oil and waste animal oil), and more preferably includes at least one selected from the group consisting of vegetable oil and its waste oil (waste vegetable oil). Examples of vegetable oils include sesame oil, soybean oil, rice oil, rapeseed oil, sunflower oil, olive oil, corn oil, cottonseed oil, peanut oil, safflower oil, etc. The vegetable oil preferably includes at least one selected from the group consisting of sesame oil, soybean oil, and rice oil. Examples of animal fat oils include beef tallow, lard, fish oil, etc. Commercially available oils can be used as the oil containing unsaturated fatty acids, and the oils containing unsaturated fatty acids can be used individually or in combination.

[0035] The mixing method and apparatus for obtaining a mixture by mixing a biomass material (A) with an oil containing unsaturated fatty acids (B) may be any commonly used mixing method and apparatus, and are not particularly limited as long as they can be used for the method of producing biochar or carbonizing biomass material that is the subject of the present invention.

[0036] The biochar production method and biomass material carbonization method of the embodiment of the present invention include supplying an oxygen-containing gas to a mixture to generate heat and carbonize it to obtain biochar, or carbonizing it by generating heat. The method of supplying the oxygen-containing gas to the mixture, the supply conditions, and the supply apparatus are not particularly limited, as long as they can be used for the biochar production method or biomass material carbonization method targeted by the present invention. Examples of the method of supplying the oxygen-containing gas to the mixture, the supply conditions, and the supply apparatus are shown in the examples. The methods and apparatus described in Patent Document 5 and Non-Patent Document 1 may also be referenced.

[0037] The oxygen-containing gas preferably contains at least one selected from the group consisting of air and oxygen, and more preferably contains air. The amount of oxygen supplied can be adjusted to an appropriate amount by observing the heat generated by the mixture. The amount of oxygen supplied is not particularly limited as long as the biochar production method or biomaterial carbonization method targeted by the present invention can be performed.

[0038] To the mixture, add an oxygen-containing gas equivalent to 0.80 gO200. ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ It is preferable to supply it as follows: 1.00 gO ２ h －１ kg-AFS －１ Total: 26.0 g ２ h －１ kg-AFS －１ It is more preferable to supply it as follows: 1.25 gO ２ h －１ kg-AFS －１ Total 20.0 g ２ h －１ kg-AFS －１ It is even more preferable to supply it as follows: 1.50 gO ２ h －１ kg-AFS －１ Total 13.0 g ２ h －１ kg-AFS －１ It is even more preferable to supply as follows: Here, "kg-AFS －１ " refers to the amount per kilogram of ash-free solids (AFS). The mixture contains an oxygen-containing gas equivalent to 0.80 gO20 ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ When supplied as described below, the oxygen supply is more appropriate, allowing for better control of the heat generated by the mixture and potentially enabling a proper transition from microbial oxidation to chemical oxidation.

[0039] It is preferable to supply an oxygen-containing gas to the mixture in terms of oxygen supply amount according to the following three temperature ranges. Below 70°C, the oxygen-containing gas is supplied at a pressure of 0.1 MPa or more and less than 1.5 MPa, at a rate of 1.67 g O ２ h －１ kg-AFS －１ or more and 20.0 g O ２ h －１ kg-AFS －１ or less, more preferably at a pressure of 0.1 MPa or more and less than 1.2 MPa at a rate of 2.0 g O ２ h －１ kg-AFS －１ or more and 16.0 g O ２ h －１ kg-AFS －１ or less, even more preferably at a pressure of 0.1 MPa or more and less than 1.0 MPa at a rate of 3.0 g O ２ h －１ kg-AFS －１ or more and 12.0 g O ２ h －１ kg-AFS －１ or less. At a temperature of 70°C or more and 100°C or less, the oxygen-containing gas is supplied at a pressure of 0.5 MPa or more and less than 1.5 MPa at a rate of 0.80 g O ２ h －１ kg-AFS －１ or more and 3.34 g O ２ h －１ kg-AFS －１ or less, more preferably at a pressure of 0.6 MPa or more and less than 1.4 MPa at a rate of 1.00 g O ２ h －１ kg-AFS －１ or more and 3.00 g O ２ h －１ kg-AFS －１ or less, even more preferably at a pressure of 0.7 MPa or more and less than 1.3 MPa at a rate of 1.20 g O ２ h －１ kg-AFS －１ or more and 2.50 g O ２ h －１ kg-AFS －１ or less. When the temperature exceeds 100°C, the oxygen-containing gas is supplied at a pressure of 0.1 MPa or more and less than 1.5 MPa at a rate of 0.80 g O２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ It is preferable to supply it as follows: at a pressure of 0.2 MPa or more and less than 1.4 MPa, 2.00 gO ２ h －１ kg-AFS －１ Total 25.0 gO ２ h －１ kg-AFS －１ It is more preferable to supply it as follows: at a pressure of 0.4 MPa or more and less than 1.3 MPa, 4.00 gO ２ h －１ kg-AFS －１ Total 20.0 g ２ h －１ kg-AFS －１ It is even more preferable to supply the oxygen-containing gas in the following conditions: As described above, when the oxygen-containing gas is supplied in three temperature ranges (below 70°C, 70°C to 100°C, and above 100°C) at specific pressures and oxygen supply rates, the heat generation of the mixture can be controlled more appropriately, and it may be possible to rapidly transition from microbial oxidation reactions to chemical oxidation reactions.

[0040] In the biochar production method of the embodiment of the present invention and the biomass material carbonization method described later, the supply of oxygen-containing gas to the mixture is started at room temperature (for example, 5 to 45°C). When the temperature of the mixture is below 70°C, an exothermic reaction by microbial oxidation is started in the mixture, raising the temperature of the mixture. When the temperature of the mixture is between 70°C and 100°C, the mixture is heated by a chemical oxidation reaction in addition to the microbial oxidation reaction, and the exothermic reaction of the mixture gradually shifts from the microbial oxidation reaction to the chemical oxidation reaction. When the temperature of the mixture exceeds 100°C, the exothermic reaction of the mixture fully shifts from the microbial oxidation reaction to the chemical oxidation reaction, further heating the mixture and carbonizing it. The temperature of the mixture can reach 300°C. Furthermore, the temperature of the mixture can be raised to a temperature exceeding 300°C. The maximum temperature to which the temperature of the mixture is raised can be determined by considering the degree of carbonization of the biochar (or the degree of carbonization of the biomass material). Higher temperatures result in a greater degree of carbonization.

[0041] The exothermic reaction of the mixture can be easily carried out by stopping the supply of oxygen-containing gas (aeration). Furthermore, in order to prevent further decomposition of the obtained biochar, it is preferable to reduce the pressure after stopping the exothermic reaction and lower the temperature of the mixture while supplying nitrogen gas.

[0042] In other parts of the present invention, the present invention provides a method for carbonizing biomass material, which includes: mixing a biomass material (A) with an oil (B) containing unsaturated fatty acids to obtain a mixture; and supplying an oxygen-containing gas to the mixture to generate heat and carbonize it.

[0043] The description of the method for producing biochar according to the embodiments of the present invention can be applied with reference to the method for carbonizing biomass material according to the embodiments of the present invention.

[0044] The present invention will be described in detail below with reference to examples and comparative examples, but these examples represent only one aspect of the present invention, and the present invention is not limited in any way by these examples.

[0045] Biomass material (A) Dairy cow manure (a1) with moisture content adjusted to 60.7% by mass Dairy cow manure was collected at Hokkaido University's experimental farm, and its moisture content was reduced to 60.7% by mass (with the total wet manure being 100% by mass) by air drying at room temperature, and then stored in a freezer at -21°C. Typical analytical values ​​for dairy cow manure with a moisture content of 60.7% by mass (with the wet manure being 100% by mass) are shown in Table 1.

[0046]

[0047] Unsaturated fatty acids (B) Sesame oil (b1), rice bran oil (b2), soybean oil (b3), and waste cooking oil (b4) were used. Sesame oil (b1) (Ajinomoto Co., Inc.'s "Pure Sesame Oil for Sesame Oil Lovers" (product name), containing 80.8% by mass of unsaturated fatty acids and 42.4% by mass of polyunsaturated fatty acids) Rice bran oil (b2) (contains 74.0% by mass of unsaturated fatty acids and 33.2% by mass of polyunsaturated fatty acids) Soybean oil (b3) (Riken Agricultural Chemicals Co., Ltd.'s "Domestic Soybean Oil" (product name), containing 82.8% by mass of unsaturated fatty acids and 56.0% by mass of polyunsaturated fatty acids) Waste cooking oil (b4) (provided from the Hokkaido University cafeteria, containing 86.0% by mass of unsaturated fatty acids and 31.4% by mass of polyunsaturated fatty acids) The iodine value, composition, and HHV of these are shown in Table 2.

[0048]

[0049] The analytical methods for the items listed in Tables 1 and 2 are shown below. Moisture content and ash content were measured by drying the sample in an oven at 105°C for 24 hours to obtain an oven-dried sample, and then burning the oven-dried sample in a FUL220FA (product name) electric muffle furnace (manufactured by Advantec Co., Ltd.) at 600°C for 3 hours. Volatile matter was measured according to ASTM E872-82 (ASTM, 2013), by heating the above oven-dried sample in an ICKV electric furnace for volatility measurement (manufactured by Ishizuka Electric Works) at 950±20°C for 7 minutes and measuring the mass loss. Furthermore, fixed carbon (FC) was determined by subtracting volatile matter and ash content from 100. Elemental analysis of carbon (C), hydrogen (H), and nitrogen (N) was performed using a CE-440 elemental analyzer (manufactured by Exter Analytical). Oxygen (O) was determined by the formula: O = 100 - C - H - N. The HHV (higher heating value [MJ / kg]) was measured using an OSK200 (product name) cylinder calorimeter (manufactured by Ogawa Sampling Co., Ltd.). Fatty acid composition and iodation were measured according to the JOCS standard method for the analysis of fats, oils and related materials.

[0050] In Example 1, carbonization of biomass material and production of biochar, 100% by mass of the portion of dairy cow manure (a1) from which the moisture content was adjusted to 60.7% by mass was used, and 3 parts by mass of sesame oil (b1) were added to obtain a mixture containing biomass material (a1) and unsaturated fatty acids. This mixture contains 2.42% by mass of unsaturated fatty acids and 1.27% by mass of polyunsaturated fatty acids. Furthermore, if 100% by mass of dairy cow manure (a1) adjusted to a moisture content of 60.7% by mass is used, it contains 0.951% by mass of unsaturated fatty acids and 0.499% by mass of polyunsaturated fatty acids.

[0051] The heating of the biomass material due to the exothermic reaction of microbial oxidation and chemical oxidation was carried out in accordance with the method described in Patent Document 5. The experimental apparatus is schematically shown in Figure 1. A stainless steel pressure vessel of approximately 1 L was used as the reaction vessel 100. The walls of the vessel were double-walled separated by air, maintaining the insulation of the inside of the vessel. The above-mentioned mixture was placed in the reaction vessel 100. The reaction vessel 100 was placed in the oven 130. The reaction vessel was kept at 30°C in the oven, and the microbial oxidation reaction was started with the following aeration rate and pressure. As the temperature of the mixture rose, the oven temperature was also increased to prevent heat loss from the mixture from affecting the microbial oxidation reaction, and the microbial oxidation reaction was carried out under the following predetermined aeration rate and pressure conditions. When the temperature of the mixture exceeded the oven temperature due to the exothermic reaction of microbial oxidation, the oven temperature was controlled so that (i) the oven temperature was lower than the mixture temperature, and (ii) the difference between the temperature of the mixture and the oven temperature was within approximately 1.5°C. Controlling the oven temperature to maintain the mixture's temperature in this way is thought to create conditions similar to those found in the central region of the cow manure deposits in composting facilities. However, this procedure is likely unnecessary when the amount of mixture increases.

[0052] More specifically, the procedure was as follows: Air was supplied from the bottom to the top of the reaction vessel 100 using an air cylinder 10 and a mass flow controller 30 (F-201CV Series, manufactured by Bronkhorst). The pressure inside the reaction vessel 100 was adjusted to the following predetermined pressure using a back pressure regulator 120 (BP-3 Series, manufactured by Go Regulator). The amount of air supplied per 1 kg of dairy cow manure (a1) (1 kg excluding moisture and ash, referred to as dry and ash-free basis (daf) or ash-free-soil (AFS)) was set as follows at each temperature: 0.4 L below 70°C. ｎ min －１ kg ｄａｆ －１ and 0.1 MPa (gauge pressure is 0.0 MPa) (6.70 g - O ２ h －１ kg-AFS －１ ), 0.1 L at temperatures between 70°C and 100°C ｎ min －１ kg ｄａｆ －１ and 1.0 MPa (gauge pressure is 0.9 MPa) (1.67 g-O ２ h －１ kg-AFS －１ ), 0.74L when the temperature exceeds 100℃ ｎ min －１ kg ｄａｆ －１ and 1.0 MPa (gauge pressure is 0.9 MPa) (12.4 g-O ２ h －１ kg-AFS －１ The temperature was set to (O). The reaction was stopped when the temperature of the mixture reached 300°C. The concentration of gas species contained in the exhaust gas (O ２ CO, CO ２ The concentrations of each gas were measured using an oxygen sensor 180 and a gas chromatograph (GC-4000, manufactured by GL Science, Inc.). The concentrations of each gas were converted to consumption rates or generation rates according to the method described in Non-Patent Document 2.

[0053] Table 3 shows the composition, unsaturated fatty acid content, and polyunsaturated fatty acid content of the mixture in Example 1. In Table 3, the unit for biomass material (A) is parts by mass, and the unit for oil containing unsaturated fatty acids (B) is parts by mass. For biomass material (A), the amount excluding water is expressed in parts by mass. The unsaturated fatty acid content (including water) and polyunsaturated fatty acid content (including water) indicate the parts by mass of unsaturated fatty acids and polyunsaturated fatty acids, respectively, per 100 parts by mass of biomass material (A) (including water). The unsaturated fatty acid content (excluding water) and polyunsaturated fatty acid content (excluding water) indicate the parts by mass of unsaturated fatty acids and polyunsaturated fatty acids, respectively, per 100 parts by mass of biomass material (A) (excluding water). The results of Example 1 are shown in Table 3. In Example 1, 300°C was reached in 156 hours. The main properties of the biochar obtained in Example 1 are shown in Table 3.

[0054] Carbonization of biomass materials and production of biochar in Examples 2 to 6 Except that 11 parts by mass of sesame oil (b1), 43 parts by mass of sesame oil (b1), 43 parts by mass of soybean oil (b2), 43 parts by mass of rice oil (b3), or 43 parts by mass of waste cooking oil (b4) were used instead of 3 parts by mass of sesame oil (b1) in Examples 2 to 6, the same method as described above for carbonization of biomass materials and production of biochar in Example 1 was used. The composition of the mixtures in Examples 2 to 6, the unsaturated fatty acid content, the polyunsaturated fatty acid content, etc. are shown in Table 3. The results of Examples 2 to 6 are shown in Table 3. The time to reach 300°C in Examples 2 to 6 was 101 hours, 68 hours, 79 hours, 88 hours, and 73 hours, respectively. The main properties of the biochar obtained in Examples 2 to 6 are shown in Table 3.

[0055] The carbonization of biomass materials and the production of biochar in Comparative Examples 1 to 1' were carried out using the same method as in Example 1 described above, except that 3 parts by mass of sesame oil (b1) were not used. The unsaturated fatty acid content, polyunsaturated fatty acid content, etc. of the mixtures of Comparative Examples 1 to 1' are shown in Table 3. The results for Comparative Examples 1 to 1' are shown in Table 3. In Comparative Example 1', the time to reach 300°C was 168 hours. The main properties of the biochar obtained in Comparative Example 1' are shown in Table 3.

[0056]

[0057] In Examples 1-6, the mixtures contained unsaturated fatty acids and generated heat on their own, reaching 300°C within a certain time. In all cases, the transition from microbial oxidation to chemical oxidation was reliably and reproducibly observed. In particular, in Examples 3-6, the temperature reached 300°C in about 60-90 hours. Biochar was obtained in all cases.

[0058] In Comparative Examples 1 to 1', only biomass material (a1) was used, and no unsaturated fatty acids were added. Although the same procedure was followed in both Comparative Examples 1 to 1', different results were obtained. In Comparative Example 1, the temperature did not reach 300°C within 200 hours, and the process did not transition from microbial oxidation to chemical oxidation. On the other hand, in Comparative Example 1', the temperature reached 300°C in 168 hours, which took longer than in Example 1. Biochar was obtained in Comparative Example 1'. It was found that by using unsaturated fatty acids, it is possible to carbonize biomass material with greater reproducibility and reliability while further reducing external heating, thereby obtaining biochar.

[0059] The method for carbonizing biomass materials and the method for producing biochar according to the present invention can be used more reproducibly and reliably while further reducing external heating and external heating costs.

[0060] 10 Air cylinder, 30 Mass flow controller, 40 Automatic calculation processing unit, 50 Fan, 60 Heater, 70 and 80 Thermometer, 90 Biomass material, 100 Reaction vessel, 120 Back pressure regulator, 130 Oven, 140 Liquid collection device, 150 Gas sampling port, 160 Ammonia collection device, 170 Deodorizer, 180 Oxygen sensor,

[0061] (Related Application) This application claims priority under Article 4 of the Paris Convention or Article 41 of the Japanese Patent Act, based on Japanese Patent Application No. 2025-037696 filed in Japan on 10 March 2025. The contents of this basic application are incorporated herein by reference.

Claims

1. Obtaining a mixture by mixing a biomass material (A) containing livestock excrement and an oil (B) containing an unsaturated fatty acid including at least one selected from the group consisting of unsaturated fatty acids having 14 to 24 carbon atoms, such that the content of the unsaturated fatty acid is 2.0 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the biomass material (excluding water); supplying an oxygen-containing gas to the mixture in terms of oxygen supply amount: at a temperature lower than 70°C, under a pressure of 0.1 MPa or more and less than 1.5 MPa, at 1.67 g O ２ h －１ kg-AFS －１ or more and 20.0 g O ２ h －１ kg-AFS －１ or less; at 70°C or more and 100°C or less, under a pressure of 0.5 MPa or more and less than 1.5 MPa, at 0.80 g O ２ h －１ kg-AFS －１ or more and 3.34 g O ２ h －１ kg-AFS －１ or less; when exceeding 100°C, under a pressure of 0.1 MPa or more and less than 1.5 MPa, at 0.80 g O ２ h －１ kg-AFS －１ or more and 33.6 g O ２ h －１ kg-AFS －１ or less; and obtaining biochar by causing heat generation and carbonization; a method for producing biochar, comprising:

2. The method of production according to claim 1, wherein the livestock excrement includes the manure of cattle, pigs, or horses.

3. The method for producing according to claim 1, wherein the unsaturated fatty acid comprises at least one selected from the group consisting of unsaturated fatty acids with C16 or more and C22 or less.

4. The manufacturing method according to claim 1, wherein the biomass material (excluding water) contains unsaturated fatty acids in an amount of 5.0 parts by mass or more and 233 parts by mass or less.

5. The method for producing the unsaturated fatty acid according to claim 1, wherein the unsaturated fatty acid includes a polyunsaturated fatty acid.

6. The method for producing polyunsaturated fatty acids according to claim 5, wherein the polyunsaturated fatty acid comprises at least one selected from polyunsaturated fatty acids with C14 or more and C24 or less.

7. The manufacturing method according to claim 5, wherein the biomass material (excluding water) contains polyunsaturated fatty acids in an amount of 1.2 parts by mass or more and 170 parts by mass or less.

8. The method for producing an oil according to claim 1, wherein the oil (B) containing unsaturated fatty acids comprises at least one selected from the group consisting of vegetable oils, animal fat oils, and their waste oils.

9. The manufacturing method according to claim 1, wherein the oxygen-containing gas comprises at least one selected from the group consisting of air and oxygen.

10. Add an oxygen-containing gas to the mixture, equivalent to 0.80 gO2 in terms of oxygen supply. ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ The manufacturing method according to claim 1, supplied below.

11. Add oxygen-containing gas to the mixture, in terms of oxygen supply amount, at a pressure of 0.1 MPa or more and less than 1.2 MPa at temperatures below 70°C, at a rate of 2.0 gO ２ h －１ kg-AFS －１ Total 16.0 g ２ h －１ kg-AFS －１ Below, at temperatures between 70°C and 100°C, the pressure should be between 0.6 MPa and less than 1.4 MPa, and 1.00 gO should be used. ２ h －１ kg-AFS －１ Total 3.00g ２ h －１ kg-AFS －１ Below, when the temperature exceeds 100°C, 2.00 gO is used at a pressure of 0.2 MPa or more and less than 1.4 MPa. ２ h －１ kg-AFS －１ Total 25.0 gO ２ h －１ kg-AFS －１ The manufacturing method according to claim 1, supplied below.

12. A mixture is obtained by mixing a biomass material (A) containing livestock excrement and an oil (B) containing an unsaturated fatty acid, which includes at least one unsaturated fatty acid selected from the group consisting of C14 to C24 unsaturated fatty acids, in an amount of 2.0 to 400 parts by mass per 100 parts by mass of the biomass material (excluding water); an oxygen-containing gas is added to the mixture at a pressure of 0.1 MPa to less than 1.5 MPa, equivalent to an oxygen supply rate of 1.67 gO20 at temperatures below 70°C. ２ h －１ kg-AFS －１ Total 20.0 g ２ h －１ kg-AFS －１ Below, at temperatures between 70°C and 100°C, the pressure is 0.5 MPa or more but less than 1.5 MPa, and the amount is 0.80 gO. ２ h －１ kg-AFS －１ The above is 3.34 gO ２ h －１ kg-AFS －１ Below, when the temperature exceeds 100°C, 0.80 gO is consumed at a pressure of 0.1 MPa or more and less than 1.5 MPa. ２ h －１ kg-AFS －１ The total is 33.6 gO. ２ h －１ kg-AFS －１ The following describes a method for carbonizing biomass material, which includes supplying and generating heat to carbonize it.

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