Biomass-containing fuel

Abstract

The purpose of the present invention is to provide a biomass-containing fuel having a high proportion of biomass and excellent fluidity. The present invention is a biomass-containing fuel comprising a carbonized product produced by steam-roasting plant biomass, a dispersant, and water, wherein the percentage of the carbonized product produced by steam-roasting plant biomass is at least 40 mass% relative to 100 mass% of the biomass-containing fuel.

Description

Biomass-containing fuel

[0001] The present invention relates to a biomass-containing fuel, and more particularly to a biomass-containing fuel that is suitable for use as a fuel for diesel engines, boilers, gas turbines, etc., and as a sustainable aviation fuel.

[0002] Slurry fuels, which are made by adding a liquid such as water to powdered solid fuel such as coal, are being developed as an alternative to liquid fuels such as heavy oil. Regarding coal slurry fuels, for example, Patent Document 1 discloses a coal-water slurry containing low-rank coal and high-rank coal, characterized in that the average particle size of the high-rank coal particles is larger than the average particle size of the low-rank coal particles.

[0003] The increase in carbon dioxide emissions due to the mass consumption of fossil fuels is a major factor in global warming, and there is a need to reduce carbon dioxide emissions. Plant biomass, such as wood, emits carbon dioxide when burned. However, this carbon dioxide is absorbed during the plant's growth process and does not affect the increase or decrease in atmospheric carbon dioxide. Therefore, the use of plant biomass as a fuel is expected to contribute to the realization of a carbon-neutral society. Patent Document 2 discloses a method for producing a biomass water slurry, which includes a reforming process in which a cellulosic biomass raw material is reformed in the presence of water at a pressure equal to or greater than the saturated vapor pressure; a separation process in which the reforming reaction product obtained in the reforming process is separated into a solid component and a liquid component; a grinding process in which the solid component obtained in the separation process is ground to an average particle size of 30 μm or less using a grinding means; and a kneading process in which the solid component is kneaded with an additive and, if necessary, water, and the grinding and kneading processes are performed simultaneously or sequentially in this order.

[0004] JP 2000-290673 A JP 2003-129069 A

[0005] As mentioned above, fuels using plant biomass have been developed in the past, but there is a need for further development of biomass-containing fuels that have a high biomass content to increase calorific value and also have excellent fluidity from the perspective of handleability, etc.

[0006] The present invention has been made in view of the above-mentioned current situation, and aims to provide a biomass-containing fuel that has a high biomass content and excellent fluidity.

[0007] The inventors conducted extensive research into fuels containing biomass and discovered that using steamed carbonized plant biomass provides excellent fluidity even when the content is increased to 40 mass% or more. This led to the realization that the above-mentioned problems could be successfully solved, and led to the present invention.

[0008] The present invention encompasses the following biomass-containing fuels, etc. [1] A biomass-containing fuel comprising a steamed charcoal of plant biomass, a dispersant, and water, wherein the content of the steamed charcoal of plant biomass is 40% by mass or more relative to 100% by mass of the biomass-containing fuel. [2] The biomass-containing fuel according to [1] above, wherein the steamed charcoal of plant biomass is steamed at a temperature of 250 to 450°C. [3] The biomass-containing fuel according to [1] or [2] above, wherein the steamed charcoal of plant biomass has an average circularity (area) of 0.5 or more and 1 or less for particles falling within ±10% of the average particle diameter (volume basis) as measured by dynamic light scattering. [4] The biomass-containing fuel according to any one of [1] to [3] above, wherein the proportion of particles in the steamed charcoal of plant biomass having a particle diameter of 50 μm or less is 95% or more. [5] The biomass-containing fuel according to any one of [1] to [4] above, wherein the steamed carbonized product of plant biomass has an average particle size of 0.1 μm or more and 20 μm or less. [6] The biomass-containing fuel according to any one of [1] to [5] above, wherein the viscosity of the biomass-containing fuel is 1000 mPa·s or less. [7] A method for producing a biomass-containing fuel, comprising: a step of carbonizing plant biomass by steaming; a step of pulverizing the carbonized product obtained in the carbonization step; and a step of mixing the pulverized product obtained in the pulverization step with a dispersant and water.

[0009] The biomass-containing fuel of the present invention has the above-described configuration, a high biomass content, and excellent fluidity, and therefore can be suitably used as fuel for diesel engines, boilers, gas turbines, etc., and as sustainable aviation fuel. In particular, it can be suitably used as fuel for boilers, gas turbines, etc.

[0010] Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description and can be appropriately modified and applied within the scope of the present invention. Note that a combination of two or more of the individual preferred embodiments of the present invention described below also falls within the scope of the present invention.

[0011] [Biomass-Containing Fuel] The biomass-containing fuel of the present invention comprises a steamed charcoal of plant biomass, a dispersant, and water, and the content of the steamed charcoal of plant biomass is 40% by mass or more relative to 100% by mass of the biomass-containing fuel. The use of the steamed charcoal of plant biomass provides the biomass-containing fuel with excellent fluidity. Furthermore, the content of the steamed charcoal of plant biomass of 40% by mass or more provides excellent combustibility. The content of the steamed charcoal of plant biomass in the biomass-containing fuel is preferably 40 to 70% by mass, more preferably 43 to 65% by mass, even more preferably 45 to 65% by mass, even more preferably 50 to 65% by mass, and particularly preferably 50 to 60% by mass.

[0012] The content of the dispersant in the biomass-containing fuel is not particularly limited, but is preferably 0.01 to 10 mass% relative to 100 mass% of the steamed carbonized plant biomass, more preferably 0.1 to 5 mass%, even more preferably 0.5 to 3 mass%, even more preferably 1 to 2.5 mass%, and particularly preferably 1.5 to 2 mass%.

[0013] The water in the biomass-containing fuel evaporates and expands in volume during fuel combustion, and therefore also serves as a power energy source for driving an internal combustion engine. The water content can be determined depending on the application of the fuel, taking into consideration the balance with the calorific value derived from the carbide. The water content is not particularly limited, but is preferably 30 to 60 mass% relative to 100 mass% of the biomass-containing fuel. It is more preferably 35 to 57 mass%, even more preferably 35 to 55 mass%, even more preferably 35 to 50 mass%, and particularly preferably 40 to 50 mass%. The water contained in the biomass-containing fuel may be recovered water generated during steaming.

[0014] The biomass-containing fuel may contain other components in addition to the steamed carbonized plant biomass, dispersant, and water. The content of the other components is not particularly limited, but is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the biomass-containing fuel.

[0015] The viscosity of the biomass-containing fuel is preferably 1000 mPa·s or less. This provides the biomass-containing fuel with superior fluidity, making it easier to handle and transport. The viscosity of the biomass-containing fuel is more preferably 800 mPa·s or less, even more preferably 600 mPa·s or less, and particularly preferably 500 mPa·s or less. The viscosity of the biomass-containing fuel can be measured by the method described in the Examples.

[0016] The biomass-containing fuel may have thixotropy or rheopexy, but preferably has thixotropy.

[0017] The theoretical calorific value of the biomass-containing fuel is preferably 2000 to 8000 kcal / kg. More preferably, it is 2500 to 7000 kcal / kg, and even more preferably, it is 3000 to 6000 kcal / kg. The theoretical calorific value can be calculated as follows: Biomass-containing calorific value = Steamed char calorific value (measured value) × Steamed char content The calorific value of the fuel can also be measured in accordance with JIS K2279:2003.

[0018] The essential and optional components contained in the biomass-containing fuel of the present invention will be further described below.

[0019] <Steamed Charcoal of Plant Biomass> The steamed charcoal of plant biomass is not particularly limited as long as it is obtained by carbonizing plant biomass by steaming. The plant biomass is not particularly limited as long as it is an organic material derived from a plant, and examples of plants include woody plants and herbaceous plants. Examples of woody plants include coniferous trees such as cedar, fir, cypress, Japanese cypress, pine, ginkgo, Japanese nut, and yew, and broad-leaved trees such as eucalyptus, acacia, birch, beech, oak, katsura, sawtooth oak, cherry, zelkova, maple, chestnut, oak, paulownia, poplar, teak, and mahogany. Among these, cedar and acacia are preferred. Examples of herbaceous plants include rice (straw, rice husk), wheat (straw, rice husk), buckwheat (straw, rice husk), sugarcane (bagasse), Erianthus, corn, rapeseed, soybean, palm, reed, bamboo, bamboo, and sugar beet. Of these, sugarcane (bagasse) is preferred. As the plant for the plant biomass, woody plants are preferred because they have a low ash content.

[0020] The ash content of the steamed carbonized plant biomass is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 3% by mass or less. The ash content can be measured, for example, according to JIS M8812:2004.

[0021] The steamed carbonized plant biomass preferably has a nitrogen content of 1.0% by mass or less, more preferably 0.7% by mass or less, and even more preferably 0.5% by mass or less. The nitrogen content can be measured, for example, according to JIS M8813:2004.

[0022] The carbonized product of plant biomass preferably has a sulfur content of 0.5% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less. The sulfur content can be measured, for example, according to JIS M8813:2004.

[0023] The steamed carbonized plant biomass preferably has an average particle circularity (area) of 0.5 or more and 1 or less, the average particle diameter of which is within ±10% of the average particle size as measured by dynamic light scattering. Because plant biomass is carbonized while retaining the plant tissue structure, the carbonized product also retains a structure similar to plant tissue, and the pulverized product obtained by pulverizing such a carbonized product also retains a complex shape. When the carbonized particles have a complex shape, the interaction between particles in the biomass-containing fuel may increase, resulting in increased viscosity. However, if the particle circularity (area) is within the above range, this increase in viscosity can be suppressed and dispersion fluidity can be further improved. Furthermore, by more thoroughly pulverizing the steamed carbonized plant biomass, the complex shape of the plant biomass is reduced, but the viscosity increases with increasing surface area. However, by pulverizing the particle circularity (area) within the above range, the increase in viscosity associated with increased surface area can be suppressed. The average circularity (area) of the particles is more preferably 0.52 to 1, even more preferably 0.55 to 1, still more preferably 0.6 to 1, and particularly preferably 0.65 to 1. The circularity (area) of the particles is the ratio of the projected area of ​​each particle to the circle-equivalent area calculated from the circumferential length of the particle, and is given by: Circularity = 4π × [projected area of ​​particle] × (1 / (circumferential length of particle) ２ ) and can be measured by the method described in the Examples.

[0024] The steamed charcoal of plant biomass preferably has a particle size of 100 μm or less at a rate of 95% or more. Plant tissue has a honeycomb structure, and the charcoal also has a similar shape. When crushed, the honeycomb structure is broken down, and this complex structure significantly affects the fluidity during dispersion. However, if the particle size rate of 100 μm or less is 95% or more, the influence of the complex structure of the plant tissue is eliminated, and the fluidity of the dispersed charcoal is further improved. This results in the biomass-containing fuel of the present invention being easier to handle and transport. The steamed charcoal of plant biomass more preferably has a particle size of 50 μm or less at a rate of 95% or more, and even more preferably has a particle size of 30 μm or less at a rate of 95% or more. The particle size of the steamed charcoal of plant biomass and the calculation of the particle size rate can be performed using the method described in the Examples.

[0025] The steamed charcoal of plant biomass preferably has an average particle size of 0.1 μm or more and 20 μm or less. If the average particle size is 20 μm or less, the fluidity of the charcoal during dispersion is further improved, and if the average particle size is 0.1 μm or more, thickening due to an increase in the specific surface area of ​​the charcoal can be sufficiently suppressed. The average particle size is more preferably 0.5 to 15 μm, even more preferably 1 to 10 μm, even more preferably 1 to 9 μm, still more preferably 1 to 8 μm, particularly preferably 1 to 6 μm, and especially more preferably 2.5 to 6 μm. The average particle size of the steamed charcoal of plant biomass can be measured by the method described in the Examples.

[0026] The steamed charcoal of plant biomass is obtained by steaming the raw plant biomass. The resulting charcoal is semi-carbonized and has excellent pulverizability. The steamed charcoal of plant biomass is preferably produced by a process of carbonizing plant biomass by steaming. The steaming temperature is not particularly limited, but is preferably 250 to 550°C. A steaming temperature of 250°C or higher allows efficient carbonization and provides excellent productivity, while a steaming temperature of 550°C or lower further improves the yield of the charcoal. Furthermore, if the steaming temperature is within the above range, the molecular weight of the volatile components obtained in the process of carbonizing the plant biomass falls within a suitable range, and the obtained volatile components can also be suitably used as fuel, etc. The steaming temperature is more preferably 250 to 500°C, even more preferably 260 to 450°C, even more preferably 300 to 430°C, and particularly preferably 350 to 400°C. Preferred conditions for the step of carbonizing the plant biomass by steaming will be described later in the section on the method for producing biomass-containing fuel.

[0027] <Dispersant> The dispersant contained in the biomass-containing fuel of the present invention is not particularly limited as long as it can disperse the steamed carbonized product of plant biomass in water. For example, (i) polyalkylarylsulfonate-based dispersants such as naphthalenesulfonic acid formaldehyde condensates; melamine formalin resin sulfonate-based dispersants such as melamine sulfonic acid formaldehyde condensates; aromatic aminosulfonate-based dispersants such as aminoarylsulfonic acid-phenol-formaldehyde condensates; lignin sulfonates such as lignin sulfonates and modified lignin sulfonates; Salt-based dispersants: polystyrene sulfonate-based dispersants; various sulfonic acid-based dispersants having a sulfonic acid group in the molecule, such as nonylphenylol sulfonate; (ii) copolymers obtained from polyalkylene glycol mono(meth)acrylate-based monomers, (meth)acrylic acid-based monomers, and monomers copolymerizable with these monomers, as described in JP-B No. 59-18338 and JP-A No. 7-223852; JP-A Nos. 10-236858, 2001-220417, 2002-121055, and 2002-121056 various polycarboxylic acid dispersants having a (poly)oxyalkylene group and a carboxyl group in the molecule, such as copolymers obtained from unsaturated (poly)alkylene glycol ether monomers, maleic acid monomers, or (meth)acrylic acid monomers, as described in JP-A-2006-52381; (iii) polyvinylpyrrolidone; (iv) polyacrylic acid; (v) copolymers obtained from (alkoxy)polyalkylene glycol mono(meth)acrylates, phosphoric acid monoester monomers, and phosphoric acid diester monomers, as described in JP-A-2006-52381; Copolymers having a (poly)oxyalkylene group and a phosphate ester group in the molecule; as described in JP-A-2008-517080, polycondensation products comprising a monomer having a (poly)oxyalkylene group and an aromatic ring group and / or a heterocyclic aromatic group, a monomer having a phosphoric acid (salt) group and / or a phosphate ester group and an aromatic ring group and / or a heterocyclic aromatic group, and an aldehyde compound; as described in JP-A-2015-508384, dispersants having an aromatic triazine structural unit, a polyalkylene glycol structural unit, and a phosphate ester structural unit;(vi) anionic surfactants such as alkyl sulfate ester salts, higher alcohol sulfate ester salts, nonionic ether sulfate ester salts, olefin sulfate ester salts, polyoxyethylene alkyl (alkylphenol) sulfate ester salts, alkyl allyl sulfonates, dibasic acid ester sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, and acylsarcosinates; (vii) cationic surfactants such as alkylamine salts, quaternary amine salts, and alkylpyridinium sulfate salts; (viii) nonionic surfactants such as polyoxyalkyl ethers, polyoxyethylene alkylphenol ethers, oxyethylene-oxypropylene block polymers, polyoxyethylene alkylamines, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, alkyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, polyoxyethylene fatty acid esters, aliphatic alcohol polyoxyethylene ethers, polyhydric alcohol fatty acid esters, and fatty acid ethanolamides; and (ix) amphoteric surfactants such as alkyl betaines.

[0028] The dispersant is preferably a polycarboxylic acid-based dispersant, more preferably a polycarboxylic acid-based dispersant represented by the following formula (1):

[0029] (In the formula, R １ , R ２ and R ３ are the same or different and represent a hydrogen atom or a methyl group. ４ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. (R ５ O) are the same or different and represent an oxyalkylene group having 2 to 18 carbon atoms. n represents the average number of moles of oxyalkylene groups added and is a number from 1 to 300. x represents an integer from 0 to 4. y represents 0 or 1. The copolymer includes a copolymer having a structural unit (a) derived from a polyalkylene glycol monomer (A) represented by the formula (I) and a structural unit (b) derived from an unsaturated carboxylic acid monomer (B).

[0030] R in the above formula (1) ４represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. It is preferably a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom, more preferably a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms, even more preferably a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and most preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. Examples of the hydrocarbon group include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, 3-pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, isooctyl, 2,3,5-trimethylhexyl, 4-ethyl-5-methyloctyl, 2-ethylhexyl, tetradecyl, octadecyl, and icosyl groups; phenyl groups, methylphenyl groups, ethylphenyl groups; naphthyl groups; benzyl groups, 1-phenylethyl groups, 2-phenylethyl groups, 3-phenylpropyl groups, 4-phenylbutyl groups, styryl groups (Ph-CH=C- groups), and cinnamyl groups (Ph-CH=CHCH ２ - group), 1-benzocyclobutenyl group, 1,2,3,4-tetrahydronaphthyl group and other aromatic hydrocarbon groups are preferred.

[0031] In the above formula (1), n ​​is preferably 1 to 100, more preferably 1 to 80, and even more preferably 1 to 50.

[0032] In the above formula (1), R ５ O represents an oxyalkylene group having 2 to 18 carbon atoms, and n Os are present in the polyalkylene glycol. ５ This means that all of the oxyalkylene groups represented by O may be the same or different. The number of carbon atoms in the oxyalkylene group is preferably 2 to 18, more preferably 2 to 12, even more preferably 2 to 8, and particularly preferably 2 to 4.

[0033] In the above formula (1), R ５The oxyalkylene group represented by O is an alkylene oxide adduct, and examples of such alkylene oxides include alkylene oxides having 2 to 8 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, 1-butene oxide, 2-butene oxide, and styrene oxide. More preferred are alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, and butylene oxide.

[0034] The unsaturated monocarboxylic acid monomer (B) is not particularly limited as long as it is a monomer having an unsaturated group and a group capable of forming a carbanion in the molecule, and examples thereof include (meth)acrylic acid, crotonic acid, isocrotonic acid, tiglic acid, 3-methylcrotonic acid, 2-methyl-2-pentenoic acid, α-hydroxyacrylic acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, and salts thereof. Preferred are (meth)acrylic acid, maleic acid, and salts thereof.

[0035] The content of the structural unit (a) in the copolymer is not particularly limited, but is preferably 1 to 95% by mass, more preferably 5 to 70% by mass, even more preferably 7 to 60% by mass, and particularly preferably 10 to 50% by mass, relative to 100% by mass of all structural units.

[0036] The content of the structural unit (b) in the copolymer is not particularly limited, but is preferably 5 to 99% by mass, more preferably 30 to 95% by mass, even more preferably 40 to 93% by mass, and particularly preferably 50 to 90% by mass, relative to 100% by mass of all structural units.

[0037] The weight-average molecular weight of the dispersant is not particularly limited, but is preferably 1,000 to 1,000,000. When the weight-average molecular weight is 1,000 or more, foaming during dispersion can be more sufficiently suppressed. The weight-average molecular weight is more preferably 2,000 to 500,000, and even more preferably 3,000 to 100,000. When the dispersant is a polycarboxylic acid-based dispersant, the weight-average molecular weight is preferably 3,000 to 500,000. More preferably, it is 4,000 to 300,000, even more preferably 5,000 to 100,000, even more preferably 10,000 to 80,000, and even more preferably 20,000 to 60,000. The weight-average molecular weight of the dispersant can be measured by the method described in the examples.

[0038] <Other Components> The biomass-containing fuel of the present invention may contain other components in addition to the steamed carbonized plant biomass, dispersant, and water. The other components are not particularly limited, but may include stabilizers, thickeners, viscosity reducers, ignition agents, organic solvents, water retention agents, lubricants, etc.

[0039] The stabilizer is not particularly limited, but examples thereof include ammonia, sodium hydroxide, amines, etc. Among these, ammonia is preferred.

[0040] The thickener is not particularly limited, but examples thereof include polysaccharides, polyacrylamides, polyalkylene oxides, polyacrylic acids and salts thereof, and polyvinyl alcohols.

[0041] The viscosity reducing agent is not particularly limited, but examples thereof include glycol monoethers, glycol diethers, phenyl glycol ethers, and benzyl glycols.

[0042] The ignition agent is not particularly limited, but examples thereof include heavy oil, light oil, bioalcohol, etc. Among these, biobutanol, biopropanol, and bioethanol are preferred.

[0043] The organic solvent is not particularly limited, but examples thereof include alcohols having 1 to 8 carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and phenoxyethanol; glycols, such as ethylene glycol, propylene glycol, butylene glycol, and hexylene glycol; acetone; and ethyl acetate.

[0044] [Method for producing biomass-containing fuel] The method for producing biomass-containing fuel of the present invention is not particularly limited, but it is preferable to produce the fuel by carrying out the steps of carbonizing plant biomass by steaming, pulverizing the carbonized product obtained in the carbonization step, and mixing the pulverized product obtained in the pulverization step with a dispersant and water. A method for producing biomass-containing fuel including the steps of carbonizing plant biomass by steaming, pulverizing the carbonized product obtained in the carbonization step, and mixing the pulverized product obtained in the pulverization step with a dispersant and water also constitutes one aspect of the present invention.

[0045] The carbonization step is not particularly limited as long as the plant biomass is carbonized by steaming, but the steaming temperature is preferably 250 to 550°C, more preferably 250 to 500°C, even more preferably 260 to 450°C, still more preferably 300 to 430°C, and particularly preferably 350 to 400°C.

[0046] The pressure in the system during the carbonization step is not particularly limited, but is preferably 0.1 to 100 atmospheres, more preferably 0.5 to 10 atmospheres, even more preferably 1 to 5 atmospheres, and particularly preferably 1 to 3 atmospheres.

[0047] The oxygen concentration in the system during the carbonization step is not particularly limited, but is preferably 0 to 5%, more preferably 0 to 3%, and even more preferably 0 to 1%.

[0048] The baking time in the carbonization step is not particularly limited, but is preferably 3 minutes to 3 hours, and more preferably 5 minutes to 1 hour.

[0049] The equipment for carrying out the carbonization step is not particularly limited, but examples thereof include horizontal moving-bed reactors such as mesh belt continuous calciners, tunnel kilns and rotary kilns; and twin-screw extruders.

[0050] The pulverization step is not particularly limited as long as it pulverizes the carbonized material obtained in the carbonization step, and may be wet pulverization or dry pulverization. The pulverizer used in the pulverization step is not particularly limited, and examples include a hammer mill, a ball mill, a tube mill, a rod mill, a jet mill, and a bead mill. From the viewpoint of increasing the circularity of the particles, a bead mill is preferred. Furthermore, when pulverization is performed using a bead mill, the circularity of the particles can be increased by adjusting the operating conditions of the bead mill, such as the material, size and amount of beads, the amount of raw material input, and the agitator rotation speed. For example, by using beads with a relatively small diameter and setting the agitator rotation speed low, the circularity can be further improved by operating in a manner that suppresses impact force and allows frictional force to predominate.

[0051] The mixing step is not particularly limited as long as it involves mixing the pulverized material obtained in the pulverization step with a dispersant and water, but it is preferable to disperse the pulverized material in water by stirring or ultrasonic waves. In the mixing step, it is preferable to use a stirrer such as a disperser, homogenizer, line mixer, or static mixer, or an ultrasonic disperser. In the latter half of the pulverization process, a dispersant and water may be added to the pulverization mill to perform both wet pulverization and mixing.

[0052] The atmosphere in the mixing step is not particularly limited, and may be an air atmosphere or an inert gas atmosphere, but it is preferable to perform the mixing step while introducing an inert gas such as nitrogen. In addition, the mixing step is preferably performed in an explosion-proof facility.

[0053] In the method for producing a biomass-containing fuel of the present invention, a step of drying the raw plant biomass is preferably carried out before the carbonization step. The drying step is not particularly limited as long as it dries the raw plant biomass, but it is preferable to dry the raw plant biomass until the moisture content is 25% or less.

[0054] In the method for producing a biomass-containing fuel of the present invention, it is preferable to carry out a step of crushing the raw plant biomass into pieces of 50 mm or less before the carbonization step.

[0055] In the method for producing a biomass-containing fuel of the present invention, a step of filtering the composition obtained in the mixing step may be carried out after the mixing step. The filtering step preferably uses a wire mesh of 50 to 300 mesh.

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass."

[0057] <Method of measuring particle size> Pulverized biomass carbonized material was added to a 10% aqueous solution of naphthalenesulfonic acid formalin condensate so that the concentration was 10%, and the dispersion was dispersed for 15 minutes using an ultrasonic disperser. The dispersion particle size distribution of this was measured using a laser diffraction / scattering particle size distribution analyzer (dynamic light scattering particle size analyzer, LA-950V2, manufactured by Horiba, Ltd.).

[0058] <Viscosity Measurement Method> The viscosity of the biomass-containing fuels obtained in the Examples and Comparative Examples was measured at 25° C. and 5 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., TV-100, rotor #1).

[0059] <Method for measuring the weight average molecular weight of the dispersant> The weight average molecular weight was measured by a standard polystyrene conversion method using gel permeation chromatography (GPC).

[0060] <Method for measuring circularity> 10 mg of a sample was placed in a beaker, and an aqueous dispersant solution (Super T-Pol (manufactured by C.B.S. Co., Ltd.)) was added to make the volume 30 ml, followed by dispersion treatment in an ultrasonic cleaner for 2 minutes to prepare a measurement solution. The obtained measurement solution was used to measure the circularity of particles under the following measurement conditions using the following device: Analyzer: Dynamic particle size analyzer Paasche Analyzer PAS (manufactured by Hosokawa Micron Corporation) Method: Flat sheath flow method Measurement conditions Lens: Standard Measurement range: 0.5 to 300 μm Number of detected particles: Approximately 10,000 The circularity (area) data for particles falling within a range of ±10% (volume distribution) of the average particle size (volume basis) measured by the dynamic light scattering particle size analyzer in the above <Method for measuring particle size> was extracted, and the average value was taken as the average circularity (area).

[0061] Example 1: Cedar was crushed to 15 mm or less and dried to a moisture content of 15% or less. The chips were steamed at an internal temperature of 400 ° C, 1.5 revolutions per minute, and atmospheric pressure using a rotary kiln with a barrel length of 3.5 m, a tilt angle of 4 degrees, and a baffle plate installed inside. The operation was adjusted so that it took approximately 30 minutes from loading to discharge, and cedar charcoal was obtained. The obtained charcoal was coarsely crushed using a commercially available hammer mill (manufactured by LabNext, RT-34), and then a commercially available fine grinder was used to obtain charcoalized pulverized products with average particle sizes of 2.36 μm, 5.36 μm, and 7.28 μm. 1 g of cedar charcoalized pulverized product with an average particle size of 5.36 μm was weighed into a sample tube, and 0.67 g of various dispersant solutions diluted to 1.5% was added to the charcoal to make the concentration 1%. 0.33 g of water was added so that the charcoal dispersion concentration was 50%. The sample tube was sealed and dispersed for 15 minutes using an ultrasonic disperser, after which the contents were stirred with a spatula to loosen the contents, and then dispersed for another 15 minutes using the ultrasonic disperser to obtain a biomass-containing composition (biomass-containing fuel). The viscosity of the obtained composition was measured, and the results are shown in Table 1.

[0062]

[0063] Details of the dispersants used in Example 1 are as follows. (Dispersant (1): Naphthalenesulfonic acid-formalin condensate) A naphthalenesulfonic acid-formalin condensate (weight-average molecular weight: approximately 1,200) commonly used as a cement water-reducing agent was used. (Dispersant (2): Polyvinylpyrrolidone) Polyvinylpyrrolidone with a K value (characteristic viscosity value) of 30 was used. (Dispersant (3): Polycarboxylic acid-based dispersant (1)) A copolymer of methacrylic acid (MAA) and methoxypolyethylene glycol methacrylate (average number of moles of ethylene oxide added: 25) (PGM25E) (mass ratio of MAA:PGM25E = 80:20, weight-average molecular weight: 23,000) was used. (Dispersant (4): Polycarboxylic acid-based dispersant (2)) A copolymer of acrylic acid (AA), methacrylic acid (MAA), and phenoxy polyethylene glycol methacrylate (average number of moles of ethylene oxide added: 20) (PGF20E) (mass ratio of AA:MAA:PGF20E = 42:50:8, weight average molecular weight: 45,000) was used. (Dispersant (5): Polycarboxylic acid-based dispersant (3)) A copolymer of acrylic acid (AA) and methoxy polyethylene glycol methacrylate (average number of moles of ethylene oxide added: 23) (PGM23E) (mass ratio of AA:PGM23E = 35:65, weight average molecular weight: 52,000) was used. (Dispersant (6): Polycarboxylic acid-based dispersant (4)) A copolymer of acrylic acid (AA), methacrylic acid (MAA), and methoxypolyethylene glycol methacrylate (average number of moles of ethylene oxide added: 25) (PGM25E) (mass ratio of AA:MAA:PGM25E = 86:1:13, weight average molecular weight: 58,000) was used.

[0064] Comparative Example 1: 1 g of the carbonized pulverized product having an average particle size of 5.36 μm obtained in Example 1 was weighed into a sample tube, and 1 g of water was added to make the dispersion concentration 1%. The sample tube was sealed and dispersed for 15 minutes using an ultrasonic disperser, after which the contents were stirred with a spatula to loosen the material, and further dispersed for 15 minutes using the ultrasonic disperser to obtain a biomass-containing composition (biomass-containing fuel). However, the carbonized material in the composition did not disperse.

[0065] Example 2: 1 g of the pulverized cedar carbonized material obtained in Example 1 with each average particle size was weighed into a sample tube, and an aqueous solution of the dispersant (5) used in Example 1 diluted to 1.5% was added to the sample tube so that the dispersant concentration was 1% or 2% relative to the carbonized material. Water was then added while adjusting the carbonized material dispersion concentration to the concentrations listed in Tables 2 to 6. The sample tube was sealed and dispersed using an ultrasonic disperser for 15 minutes. The contents were then stirred with a spatula to loosen the contents, and the contents were dispersed using the ultrasonic disperser for another 15 minutes to obtain a biomass-containing composition (biomass-containing fuel). The viscosity of each composition obtained was measured, and the results are shown in Tables 2 to 6.

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] <Calculation of Theoretical Calorific Value> The theoretical calorific value of a composition with a 55% dispersed concentration of carbonized pulverized material was calculated using the following method and was found to be approximately 3,300 to 5,000 kcal / kg: Biomass-contained calorific value = Steamed charcoal calorific value (measured value) × Steamed char content The above result is within the combustible range of coal slurry fuel, and demonstrates that a composition with a 55% dispersed concentration of carbonized pulverized material can be suitably used as a fuel.

[0072] Examples 3 to 8 In the same manner as in Example 1, cedar charcoal was coarsely pulverized using a commercially available hammer mill (RT-34, manufactured by LabNext Co., Ltd.), and then a Pulvis PV-150 (manufactured by Hosokawa Micron Corporation) was used as a fine pulverizer, and the mill was operated while adjusting the operating conditions within the following ranges, thereby obtaining pulverized carbonized products having the particle sizes shown in Table 7. The circularity (area) of the pulverized carbonized products having each particle size was as shown in Table 7. Using the obtained pulverized carbonized products, a biomass-containing fuel was obtained in the same manner as in Example 1, except that dispersant (3) was used at 3% per solid content. The viscosity of the obtained biomass-containing fuel was measured, and the results are shown in Table 7. <Operating conditions for Pulvis PV-150> Media: 3mm stainless steel beads, 4.5kg used Raw material input speed: 5-20g / min Mill rotation speed: 300-600rpm Classifier rotation speed: 4000-23000rpm Bottom gas flow rate: 0.1-0.4Nm ３ / min

[0073] Example 9 In the same manner as in Example 1, cedar charcoal was coarsely pulverized using a commercially available hammer mill (RT-34, manufactured by LabNext Co., Ltd.) and then classified using a sieve with 20 μm openings to obtain a pulverized carbonized product with an average particle size of 20.2 μm. The circularity (area) of the obtained pulverized carbonized product was as shown in Table 7. Using the obtained pulverized carbonized product, a biomass-containing fuel was obtained in the same manner as in Example 1, except that dispersant (3) was used at 3% per solid content, so that the dispersion concentration of the charcoal was the concentration shown in Table 7. The viscosity of the obtained biomass-containing fuel was measured, and the results are shown in Table 7.

[0074]

Claims

1. It contains carbonized plant biomass, a dispersant, and water. A biomass-containing fuel in which the content ratio of carbonized plant biomass is 40% by mass or more relative to 100% by mass of the biomass-containing fuel.

2. The biomass-containing fuel according to claim 1, wherein the carbonization temperature of the carbonized plant biomass is 250 to 450°C.

3. The biomass-containing fuel according to claim 1 or 2, wherein the carbonized plant biomass has an average value of 0.5 or more and 1 or less for particles whose circularity (area) falls within ±10% of the average particle diameter (volume basis) measured by dynamic light scattering.

4. The biomass-containing fuel according to claim 1 or 2, wherein the carbonized plant biomass has a particle size of 50 μm or less, with a proportion of 95% or more.

5. The biomass-containing fuel according to claim 1 or 2, wherein the carbonized plant biomass has an average particle size of 0.1 μm or more and 20 μm or less.

6. The biomass-containing fuel according to claim 1 or 2, wherein the biomass-containing fuel has a viscosity of 1000 mPa·s or less.

7. A method for producing biomass-containing fuel, comprising the steps of: carbonizing plant biomass by steaming; crushing the carbonized material obtained in the carbonization step; and mixing the crushed material obtained in the crushing step with a dispersant and water.