Biomass solid fuel and manufacturing method of biomass solid fuel

Abstract

To provide a biomass solid fuel capable of suppressing dust scattering.SOLUTION: A biomass solid fuel includes a biomass and a mineral oil.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a biomass solid fuel and a method for producing a biomass solid fuel. [Background technology]

[0002] In recent years, biomass solid fuels that can be mixed with coal have been developed to reduce CO2 emissions, which are believed to be a cause of global warming. In the case of using a mixture of coal and biomass solid fuel in an existing pulverized coal boiler, the crushability of the biomass solid fuel is poorer than that of coal, which causes problems such as a decrease in combustion efficiency and a decrease in the efficiency of the crusher. Therefore, a method has been proposed in which the crushability is improved by carbonizing the biomass. For example, Patent Document 1 discloses a method for producing a solid fuel by heating biomass in an oxygen-deficient atmosphere, the method producing a solid fuel that is mixed with coal or pulverized alone to be used as a pulverized fuel, the method comprising the steps of: heating hard biomass including plant shells, fruits, and seeds at an oxygen concentration of 1 to 5% and a treatment temperature of 350 to 400°C for 30 to 90 minutes to carbonize the solid fuel.

[0003] On the other hand, when coal and other materials are piled up, fine dust is dispersed into the air, which causes problems in the working environment and the surrounding environment. To address this issue, a method has been proposed in which a surfactant is added to water to make it easier for the water to penetrate the pile. For example, Patent Document 2 discloses a dust suppressant containing (A) a nonionic surfactant mixture and (B) a dihydric to hexahydric polyhydric alcohol (B), with the (A) component and the (B) component being contained in a weight ratio of 9 / 1 to 2 / 8 and a total of 25 to 95% by weight. It is disclosed that the (A) nonionic surfactant mixture contains (a1) a nonionic surfactant represented by general formula (1) and (a2) a nonionic surfactant represented by general formula (2) in a weight ratio of [(a1) / (a2)] of 9 / 1 to 2 / 8. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-191085 A [Patent Document 2] JP 2005-336396 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, biomass solid fuel is transported by ship, unloaded to a storage pile by an unloader, and then transported to a power plant, etc. by ship, truck, etc. However, there is a problem that fine powder of biomass is dispersed into the air during transportation. A dust suppressant in which a surfactant is added to water, such as the dust suppressant described in Patent Document 2, has the effect of wetting fine powder, agglomerating the fine powder, and increasing the apparent particle size, thereby suppressing dust scattering. However, if a dust suppressant in which a surfactant is added to water is used for a biomass solid fuel with many pores, the dust suppressant instantly penetrates into the inside of the biomass solid fuel, reducing the probability of wetting the fine powder and making it unable to exert a sufficient effect. Therefore, although the dust suppressant described in Patent Document 2 can be applied to deposits such as ores, coal, and soil and sand, it is difficult to apply it to biomass solid fuel.

[0006] An object of the present invention is to provide a biomass solid fuel capable of suppressing dust scattering, and a method for producing the biomass solid fuel. [Means for solving the problem]

[0007] [1] Biomass solid fuel containing biomass and mineral oil.

[0008] [2] The biomass is a formed biomass pellet; At least a portion of the surface of the biomass pellets is coated with the mineral oil. The biomass solid fuel described in [1] above.

[0009] [3] The biomass solid fuel is a mineral oil-containing pellet formed from a mixture of the biomass and the mineral oil. The biomass solid fuel described in [1] above.

[0010] [4] In the biomass solid fuel, The ratio of the mineral oil to the biomass (the mineral oil / the biomass) is 1 / 1000 or more and 1 / 10 or less in mass ratio. The biomass solid fuel according to any one of [1] to [3].

[0011] [5] The higher heating value on a dry basis is 4500 kcal / kg or more and 6000 kcal / kg or less, and the fuel ratio (fixed carbon / volatile matter) is 0.2 or more and 0.7 or less. The biomass solid fuel according to any one of [1] to [4].

[0012] [6] The Hardgrove Crushability Index (HGI) is between 25 and 50; The biomass solid fuel according to any one of [1] to [5].

[0013] [7] Bulk density 500kg / m 3 More than 700kg / m 3 and the mechanical durability is 90% or more and 99% or less. The biomass solid fuel according to any one of [1] to [6].

[0014] [8] The kinetic viscosity of the mineral oil at 40°C is 7mm 2 / s or more 100mm 2 / s or less, The biomass solid fuel according to any one of [1] to [7].

[0015] [9] The flash point of the mineral oil is 150°C or higher and 300°C or lower; The biomass solid fuel according to any one of [1] to [8].

[0016]

[10] The density of the mineral oil is 0.8 g / cm 3 More than 1.0g / cm 3 Below is the The biomass solid fuel according to any one of [1] to [9].

[0017]

[11] The aniline point of the mineral oil is 90°C or higher and 150°C or lower. The biomass solid fuel according to any one of [1] to

[10] .

[0018]

[12] The average molecular weight of the mineral oil is 250 or more and 600 or less. The biomass solid fuel according to any one of [1] to

[11] .

[0019]

[13] In the ring analysis (ndM method) of the mineral oil in accordance with ASTM D-3238, the weight ratio of the aromatic carbon amount to the total carbon amount is 10% by weight or less, the weight ratio of the naphthenic carbon amount to the total carbon amount is 10% by weight or more and 40% by weight or less, and the weight ratio of the paraffinic carbon amount to the total carbon amount is 50% by weight or more and 90% by weight or less. The biomass solid fuel according to any one of [1] to

[12] .

[0020]

[14] The sulfur content of the mineral oil is 0.15% by weight or less. The biomass solid fuel according to any one of [1] to

[13] .

[0021]

[15] The color (Saybolt) of the mineral oil is -10 or more. The biomass solid fuel according to any one of [1] to

[14] .

[0022]

[16] The biomass is at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass; The biomass solid fuel according to any one of [1] to

[15] .

[0023]

[17] A biomass pellet forming step of forming the biomass into pellets; and a step of coating at least a portion of the surface of the biomass pellets obtained in the biomass pellet molding step with mineral oil. A method for producing biomass solid fuel.

[0024]

[18] A process for heating the biomass pellets obtained in the biomass pellet molding process under conditions of an oxygen concentration of 5% by mass or less and 250°C to 350°C. The method for producing a biomass solid fuel according to

[17] above.

[0025]

[19] A method of producing a biomass-based compostable oil-based compostable oil product comprising the steps of: and a mineral oil-containing pellet forming step of forming the mixture obtained in the mixing step into pellets. A method for producing biomass solid fuel.

[0026]

[20] A process for heating the mineral oil-containing pellets obtained in the mineral oil-containing pellet molding process under conditions of an oxygen concentration of 5% by mass or less and 250° C. or more and 350° C. or less. The method for producing a biomass solid fuel according to

[19] above.

[0027]

[21] The ratio of the mineral oil to the biomass (the mineral oil / the biomass) is 1 / 1000 or more and 1 / 10 or less by mass ratio; The method for producing a biomass solid fuel according to any one of

[17] to

[20] above.

[0028]

[22] The biomass is at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass; The method for producing a biomass solid fuel according to any one of

[17] to

[21] . Effect of the Invention

[0029] According to one aspect of the present invention, it is possible to provide a biomass solid fuel capable of suppressing dust scattering, and a method for producing the biomass solid fuel. [Brief description of the drawings]

[0030] [Figure 1A] 1 is a micrograph of the mixture of Example 1-1 immediately after shaking. [Figure 1B] 1 is a micrograph of the mixture of Example 1-1 one week after shaking. [Figure 2A] 1 is a micrograph of the mixture of Example 1-2 immediately after shaking. [Figure 2B] 1 is a micrograph of the mixture of Example 1-2 one week after shaking. [Figure 3A] 1 is a micrograph of the mixture of Example 1-3 immediately after shaking. [Figure 3B] 1 is a micrograph of the mixture of Example 1-3 one week after shaking. [Figure 4A] 1 is a micrograph of the mixture of Examples 1-4 immediately after shaking. [Figure 4B] 1 is a micrograph of the mixture of Examples 1-4 after one week of shaking. [Figure 5A] 1 is a micrograph of the mixture of Examples 1-5 immediately after shaking. [Figure 5B] 1 is a micrograph of the mixture of Examples 1-5 after one week of shaking. [Figure 6A] 1 is a micrograph of the mixture of Examples 1-6 immediately after shaking. [Figure 6B] 1 is a micrograph of the mixture of Examples 1-6 after one week of shaking. [Figure 7A] 1 is a micrograph of the mixture of Examples 1-7 immediately after shaking. [Figure 7B] 1 is a micrograph of the mixture of Examples 1-7 after one week of shaking. [Figure 8] 1 is a micrograph of the mixture of Comparative Example 1-1 immediately after shaking. [Figure 9A] 1 is a micrograph of the mixture of Comparative Example 1-2 immediately after shaking. [Figure 9B] 1 is a micrograph of the mixture of Comparative Example 1-2 one week after shaking. [Figure 10A] 1 is a micrograph of the mixture of Reference Example 1-1 immediately after shaking. [Figure 10B] 1 is a micrograph of the mixture of Reference Example 1-1 taken one week after shaking. [Figure 11] FIG. 2 is a schematic diagram for explaining a multistage sieve used in the evaluation of the examples. [Figure 12] FIG. 2 is a diagram showing the relationship between the particle size of BP fine powder and the abundance ratio of the fine powder. [Figure 13] FIG. 1 is a diagram showing the relationship between the particle size of BP fine powder and the proportion of fine powder present after a mechanical durability test. [Figure 14] FIG. 13 is a diagram showing the amount of dust dispersed during a drop test. [Figure 15] FIG. 2 is a diagram showing the vapor pressure curves of water and mineral oil 3 used in the examples. [Figure 16] FIG. 2 is a diagram showing vapor pressure curves of mineral oil 1 and mineral oil 2 used in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In this specification, a numerical range expressed using "to" means a range that includes the numerical value before "to" as the lower limit and the numerical value after "to" as the upper limit. In this specification, mass percent concentration (unit: mass % (mass%)) and weight percent concentration (unit: weight % (wt%)) are the same value.

[0032] [First embodiment] [Biomass solid fuel] The biomass solid fuel according to this embodiment contains biomass and mineral oil.

[0033] The present inventors conducted extensive research and found that mineral oil has a property that makes it difficult for it to instantly penetrate into the interior of biomass solid fuel. When mineral oil with such a property is added to a biomass solid fuel with many pores, a certain amount of the mineral oil penetrates into the interior of the biomass solid fuel, and the probability of wetting the fine powder can be increased. This allows the effect of the mineral oil (the effect of wetting and agglomerating the fine powder) to be exerted on the fine powder that is generated when the part into which the mineral oil has penetrated is broken, and as a result, dust scattering is suppressed. According to the biomass solid fuel of this embodiment, it is possible to suppress the scattering of dust during transportation or storage. In addition, since the scattering of dust can be suppressed, it is also possible to suppress the decrease in work efficiency, the ignition of dust, and the occurrence of fires due to the ignition of dust. In addition, there is a demand for increasing the amount of biomass solid fuel used in power plants. According to the present embodiment, a biomass solid fuel with improved safety can be obtained, so that the demand for increasing the amount of biomass solid fuel used can be met.

[0034] In addition, isoparaffin-based solvents (specifically IP solvents) can be used as materials to suppress dust scattering from biomass solid fuels, but in order to reduce costs, there is a demand to use materials other than isoparaffin-based solvents to suppress dust scattering.

[0035] One possible method for suppressing dust scattering is, for example, sprinkling water on the biomass solid fuel. However, sprinkling water on the biomass solid fuel has the problem that water evaporates during storage, and the biomass solid fuel needs to be watered repeatedly every time it dries out. If water is sprinkled more frequently, the moisture content in the biomass solid fuel increases and the calorific value decreases, which can be a hindrance to operation, for example, when using the biomass solid fuel in a boiler. On the other hand, mineral oil has a significantly lower vapor pressure than water and is less likely to volatilize, as shown in Figures 15 and 16. In other words, once mineral oil is added to biomass fuel, it is not necessary to add more mineral oil thereafter because it is less likely to volatilize, and the dust suppression effect can be maintained for a long period of time. In the biomass solid fuel of this embodiment, the effect of suppressing dust scattering is believed to be due in part to the property of mineral oil that is less volatile. According to the biomass solid fuel of this embodiment, since it contains mineral oil having the above-mentioned properties (the property of not easily penetrating instantly into the interior of the biomass solid fuel and the property of not easily volatilizing), dust scattering can be suppressed in a simple manner compared to the conventional method of suppressing dust scattering by spraying water on the biomass solid fuel.

[0036] Examples of "transportation" during transportation of biomass solid fuel include transportation from a designated location to a loading port, transportation from the loading port to a discharging port, transportation from the discharging port to the premises of power plants, steel mills, factories, etc. in various locations, and transportation from the premises to furnaces. When storing biomass solid fuel, "storage" includes, for example, storage in an outdoor location, an indoor covered location (dome type, warehouse type, etc.), a ship's hold, a silo, and in a container (e.g., a bin), etc.

[0037] <Biomass> The biomass is not particularly limited, but examples thereof include woody biomass, herbaceous biomass, agricultural residue biomass, palm biomass, cellulose products, and pulp products. As used herein, crop residue biomass means anything other than the edible parts. As used herein, palm biomass refers to agricultural waste from palm trees that can be used as biomass fuel. The biomass is preferably at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass.

[0038] Examples of woody biomass include conifers (e.g., cedar, pine, cypress, and fir), and broad-leaved trees (e.g., acacia, eucalyptus, white birch, beech, zelkova, katsura, paulownia, rubber tree, and camphor tree). Woody biomass may also be construction waste (e.g., cut scraps, chips generated at processing plants, and sawdust), forest residues, thinned wood, and bamboo. Examples of herbaceous biomass include grasses, naturally grown plants, and artificially planted plants. Herbaceous biomass may be hemp, cotton, rice straw, rice husks, wheat straw, bamboo grass, napier grass, sorghum, and Japanese silver grass.

[0039] Crop residue biomass includes, for example, leaves, fruit clusters, stems, roots, and other non-edible parts of crops such as wheat, corn, potato, sugarcane (including bagasse), and bananas.

[0040] Examples of palm biomass include palm kernel shells (PKS), empty fruit bunches (EFB), and palm trunks. The above-mentioned biomasses may be used alone or in combination of two or more kinds.

[0041] In the biomass solid fuel according to this embodiment, the biomass is preferably at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass. The shape of the biomass is not particularly limited, and examples of the shape of the biomass include chips, long pieces, powder, and irregular shapes.

[0042] <Mineral oil> In the biomass solid fuel according to this embodiment, examples of mineral oil include atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffinic crude oil, intermediate base crude oil, naphthenic crude oil, etc.; distillate oil obtained by vacuum distillation of these atmospheric residual oils; mineral oil obtained by subjecting the distillate oil to one or more refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc.; and mineral oil (GTL) obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process or the like (GTL wax (Gas To Liquids WAX)). These mineral oils may be used alone or in combination of two or more.

[0043] (Properties of mineral oil) The properties of the mineral oil contained in the biomass solid fuel will be explained.

[0044] (Kinematic viscosity at 40°C) In the biomass solid fuel according to this embodiment, the kinetic viscosity of the mineral oil at 40°C is 7mm 2 / s or more 100mm 2 / s or less is preferable, and 20 mm 2 / s or more 90mm 2 / s or less is more preferable, and 30 mm 2 / s or more 80mm 2 It is even more preferable that the ratio is equal to or less than 1 / s. The kinetic viscosity of mineral oil at 40°C is 7mm 2 A viscosity of 100 / s or more is preferable because when mineral oil is mixed with the biomass solid fuel, the mineral oil is less likely to permeate the biomass solid fuel due to the effect of capillary action. The kinetic viscosity of mineral oil at 40°C is 100mm 2 When the mineral oil is mixed with the biomass, it is preferable that the mineral oil be dispersed in a mist form at a rate of not more than 1 / s, so that the mineral oil can be dispersed more uniformly. The kinetic viscosity at 40°C is a value measured by a method in accordance with JIS K2283 (2000).

[0045] (flash point) In the biomass solid fuel according to this embodiment, the flash point of the mineral oil is preferably 150°C or higher and 300°C or lower, more preferably 155°C or higher and 290°C or lower, and even more preferably 160°C or higher and 280°C or lower. In this specification, the flash point is the flash point according to the Cleveland open cup flash point (COC method). The Cleveland open cup flash point is a value measured in accordance with JIS K 2265-4 (2007).

[0046] (density) In the biomass solid fuel according to this embodiment, the density of the mineral oil is 0.8 g / cm 3 More than 1.0g / cm 3 It is preferable that the density is 0.81 g / cm or less. 3 More than 0.89g / cm 3 More preferably, it is 0.82 g / cm or less. 3 More than 0.88g / cm 3 It is even more preferable that: Density (15°C) is a value measured in accordance with JIS K 2249-1 (2011) (Crude oil and petroleum products - Determination of density - Part 1: Vibration method).

[0047] (Aniline point) In the biomass solid fuel according to this embodiment, the aniline point of the mineral oil is preferably 80°C or higher and 150°C or lower, more preferably 85°C or higher and 140°C or lower, and even more preferably 90°C or higher and 130°C or lower. The aniline point is a value measured in accordance with JIS K 2256 (2013).

[0048] (average molecular weight) In the biomass solid fuel according to this embodiment, the average molecular weight of the mineral oil is preferably 250 or more and 600 or less, more preferably 260 or more and 580 or less, and even more preferably 270 or more and 550 or less. The average molecular weight of mineral oil is a value calculated based on ASTM D2502.

[0049] (Weight ratio of aromatic carbon to total carbon) In the biomass solid fuel according to this embodiment, in a ring analysis (ndM method) of mineral oil in accordance with ASTM D-3238, it is preferable that the weight ratio of aromatic carbon content to total carbon content is 10% by weight or less, the weight ratio of naphthenic carbon content to total carbon content is 10% by weight or more and 50% by weight or less, and the weight ratio of paraffinic carbon content to total carbon content is 50% by weight or more and 90% by weight or less. The weight ratio of the amount of aromatic carbon to the total amount of carbon is more preferably 8% by weight or less, and further preferably 5% by weight or less. The weight ratio of the naphthenic carbon amount to the total carbon amount is more preferably 13% by weight or more and 45% by weight or less, and further preferably 15% by weight or more and 40% by weight or less. The weight ratio of the paraffin carbon amount to the total carbon amount is more preferably 52% by weight or more and 85% by weight or less, and further preferably 55% by weight or more and 80% by weight or less. The weight ratio of the aromatic carbon amount to the total carbon amount, the weight ratio of the naphthenic carbon amount to the total carbon amount, and the weight ratio of the paraffinic carbon amount to the total carbon amount are each a value calculated by ring analysis (ndM method) in accordance with ASTM D3238 (1995). The weight ratio of aromatic carbon to total carbon is sometimes called aromatic content (%CA). The weight ratio of naphthenic carbon to total carbon is sometimes called naphthenic content (%CN). The weight ratio of paraffinic carbon to total carbon is sometimes called paraffinic content (%CP).

[0050] (Sulfur content) In the biomass solid fuel according to this embodiment, the sulfur content of the mineral oil is preferably 0.15% by weight or less, more preferably 0.13% by weight or less, and even more preferably 0.1% by weight or less. The sulfur content is measured in accordance with the ultraviolet fluorescence method of JIS K 2541-6 (2013) when it is less than 0.05% by mass (500 ppm by mass), and in accordance with the wavelength dispersive X-ray fluorescence method of JIS K2541-7 (2013) when it is 0.05% by mass (500 ppm by mass) or more.

[0051] (Hue (Saybolt)) In the biomass solid fuel according to this embodiment, the hue (Saybolt) of the mineral oil is preferably not less than -10, more preferably not less than +10, and even more preferably not less than +20. Since the mineral oil becomes more colorless as its hue approaches +30, if the hue of the mineral oil is within the above range, for example, when the color of the biomass solid fuel is whitish, the color is more likely to be maintained. Hue (Saybolt) is a value measured using a method conforming to JIS K2580 (2003).

[0052] The biomass solid fuel according to this embodiment is preferably in the form of pellets. In this specification, the pellet includes briquettes. The size and shape of the pellet are not particularly limited, but the pellet is usually cylindrical and preferably has a diameter of 5 mm to 10 mm and a length of 5 mm to 50 mm.

[0053] In the biomass solid fuel according to this embodiment, the biomass is in the form of formed biomass pellets, and it is preferable that at least a portion of the surface of the biomass pellets is coated with mineral oil. In the biomass solid fuel of this embodiment, the surface of the biomass pellets is preferably covered by 50% or more of the mineral oil, more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, and even more preferably 90% or more.

[0054] The biomass solid fuel according to this embodiment may be a mineral oil-containing pellet formed from a mixture of biomass and mineral oil.

[0055] In the biomass solid fuel of this embodiment, the ratio of mineral oil to biomass (the mineral oil / the biomass) is, in mass ratio, preferably 1 / 1000 or more and 1 / 10 or less, more preferably 1 / 200 or more and 1 / 20 or less, and even more preferably 1 / 100 or more and 3 / 100 or less.

[0056] In the biomass solid fuel of this embodiment, the biomass content is preferably 50 mass% or more and 99.9 mass% or less, more preferably 80 mass% or more and 99.9 mass% or less, and even more preferably 90 mass% or more and 99.9 mass% or less, relative to the total amount of the biomass solid fuel. In the biomass solid fuel according to this embodiment, the mineral oil content is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 1% by mass or more and 3% by mass or less, relative to the total amount of the biomass solid fuel. The upper limit of the total content of biomass and mineral oil in the biomass solid fuel is 100 mass %. Note that this embodiment does not exclude the biomass solid fuel containing materials other than biomass and mineral oil.

[0057] <Properties of biomass solid fuel> The properties of the biomass solid fuel according to this embodiment will be described.

[0058] (Higher heating value on a dry basis and fuel ratio (fixed carbon / volatile matter)) In the biomass solid fuel according to this embodiment, it is preferable that the higher heating value on a dry basis is 4500 kcal / kg or more and 6000 kcal / kg or less, and the fuel ratio (fixed carbon / volatile matter) (air-dry basis) is 0.2 or more and 0.7 or less. In the biomass solid fuel according to this embodiment, the higher heating value on a dry basis is more preferably 4600 kcal / kg or more and 5900 kcal / kg or less, and even more preferably 4700 kcal / kg or more and 5800 kcal / kg or less. The higher heating value on a dry basis is measured by a method conforming to JIS M8814 (2003).

[0059] In the biomass solid fuel according to this embodiment, the fuel ratio (fixed carbon / volatile matter) (air-dry basis) is preferably 0.2 or more and 0.7 or less, more preferably 0.21 or more and 0.68 or less, and even more preferably 0.22 or more and 0.65 or less. The amount of fixed carbon and the volatile matter are measured by a method conforming to JIS M8812 (2004).

[0060] (Hardgrove Crushability Index (HGI)) In the biomass solid fuel according to this embodiment, the Hardgrove Crushability Index (HGI) is preferably 20 or more and 50 or less, more preferably 22 or more and 48 or less, and even more preferably 25 or more and 45 or less. The Hardgrove Crushability Index (HGI) is measured using a method conforming to JIS M8801 (2008).

[0061] (Bulk density and mechanical durability) In the biomass solid fuel according to this embodiment, the bulk density is 500 kg / m 3 More than 700kg / m 3 The mechanical durability is preferably 90% or more and 99% or less. In the biomass solid fuel according to this embodiment, the bulk density is 510 kg / m 3 More than 690kg / m 3 More preferably, it is 520 kg / m or less. 3 More than 680kg / m 3 It is even more preferable that: Bulk density is measured by a method conforming to ISO 17828.

[0062] In the biomass solid fuel according to this embodiment, the mechanical durability is more preferably 91% or more and 98% or less, and further preferably 92% or more and 97% or less. The mechanical durability (unit: %) is measured by a method conforming to ISO 17831-1.

[0063] (Other components of biomass solid fuel) The biomass solid fuel according to this embodiment may contain other components, such as binders and various additives, within the scope of not impairing the effect of this embodiment (suppression of dust scattering). The content of other components is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1% by mass or less, based on the total amount of the biomass solid fuel.

[0064] The biomass solid fuel according to this embodiment may include coal. Coal includes, for example, bituminous coal, subbituminous coal, and lignite. Bituminous coal: Coal with a total calorific value of 8100 kcal / kg or more and less than 8400 kcal / kg on an ash-free and dry basis. Sub-bituminous coal: Coal with a total calorific value of 7,300 kcal / kg or more and less than 8,100 kcal / kg on an ash-free and dry basis. Lignite: Coal with a total calorific value of 5,800 kcal / kg or more and less than 7,300 kcal / kg on an ash-free, dry basis.

[0065] From the viewpoint of ease of molding, the particle size of the coal is preferably 1 mm or less, more preferably 110 μm or less. The lower limit of the particle size of the coal is more than 0. The particle size of the coal can be adjusted, for example, by using a sieve.

[0066] When the biomass solid fuel of this embodiment contains coal, the ratio of coal to biomass in the biomass solid fuel (coal / biomass) is preferably more than 0 / 100 and not more than 75 / 25, more preferably more than 0 / 100 and not more than 50 / 50, in mass ratio.

[0067] [Use of biomass solid fuel] The biomass solid fuel according to the present embodiment can be widely used in power plants, steel mills, factories, etc. The biomass solid fuel according to the present embodiment may be burned alone or may be mixed with other fuels such as coal and burned (co-combustion). For example, when the biomass solid fuel is used in a thermal power generation facility, the biomass solid fuel may be crushed in a crusher and then introduced into the boiler, or depending on the size, it may be introduced into the boiler as is. It is also preferable to use the biomass solid fuel mixed with coal. In this case, the biomass solid fuel may be pulverized together with coal using, for example, a coal pulverizer using existing thermal power generation equipment, and these may be introduced into a boiler. In addition, the biomass solid fuel may be pulverized in a pulverizer (e.g., a pulverizer for biomass solid fuel) other than the coal pulverizer, and then mixed with separately pulverized coal and introduced into the boiler. The manner of use of the biomass solid fuel is not limited to the above.

[0068] Second Embodiment <Production method of biomass solid fuel> The biomass solid fuel manufacturing method according to the second embodiment (hereinafter also referred to as the "manufacturing method according to the second embodiment") includes a biomass pellet forming process for forming biomass into pellets, and a process for coating at least a portion of the surface of the biomass pellets obtained in the biomass pellet forming process with mineral oil. According to the production method of the second embodiment, a biomass solid fuel capable of suppressing dust scattering can be obtained.

[0069] (Biomass pellet molding process) The biomass pellet forming step is a step of forming (preferably compression molding) the biomass at a predetermined pressure, thereby obtaining biomass pellets. The pellets can be produced, for example, by extruding the biomass through a metal hole (e.g., diameter 5 mm to 10 mm, length 5 mm to 200 mm). The pellets can also be produced using a pelletizer such as a ring die type or flat die type. The pressure during molding is preferably 50 MPa to 150 MPa.

[0070] (Heating process) The manufacturing method according to the second embodiment preferably includes a step of heating the biomass pellets obtained in the biomass pellet molding step. The heating temperature in the heating step is preferably 250°C or higher and 350°C or lower, and more preferably 270°C or higher and 330°C or lower. The heating time in the heating step depends on the heating temperature, but is preferably from 10 minutes to 240 minutes, more preferably from 20 minutes to 180 minutes, and even more preferably from 30 minutes to 150 minutes.

[0071] The heating atmosphere in the heating step is not particularly limited, but is preferably a dry distillation gas atmosphere or a combustion exhaust gas atmosphere. The oxygen concentration in the heating step is preferably 5% by mass or less, and more preferably 3% by mass or less.

[0072] The manufacturing method of the second embodiment more preferably includes a step of heating the biomass pellets obtained in the biomass pellet molding step under conditions of an oxygen concentration of 5 mass % or less and at 250° C. or higher and 350° C. or lower.

[0073] (Coating process) The coating step is a step of coating at least a portion of the surface of the biomass pellets obtained in the biomass pellet molding step with mineral oil. Methods for coating at least a portion of the surface of biomass pellets with mineral oil include, but are not limited to, adding mineral oil to biomass pellets (e.g., immersing, dripping, spraying, etc.), adding mineral oil to biomass pellets and shaking the biomass pellets, and exposing the biomass pellets to an atmosphere of mineral oil.

[0074] In the coating process, the ratio of the mineral oil to the biomass pellets (mineral oil / biomass pellets) is, in mass ratio, preferably 1 / 1000 or more and 1 / 10 or less, more preferably 1 / 200 or more and 1 / 20 or less, and even more preferably 1 / 100 or more and 3 / 100 or less. The coating step may be performed before or after the heating step.

[0075] Third Embodiment <Production method of biomass solid fuel> The method for producing a biomass solid fuel according to the third embodiment (hereinafter also referred to as the "production method according to the third embodiment") includes a step of mixing biomass with mineral oil, and a step of forming the mixture obtained in the mixing step into pellets containing mineral oil. According to the production method of the third embodiment, a biomass solid fuel capable of suppressing dust scattering can be obtained.

[0076] (Mixing process) The method for mixing the biomass and the mineral oil is not particularly limited, but may be, for example, a method in which mineral oil is added to biomass pellets and then the two are mixed by a known means.

[0077] In the mixing step, the ratio of the mineral oil to the biomass (the mineral oil / the biomass) is, in mass ratio, preferably 1 / 1000 or more and 1 / 10 or less, more preferably 1 / 200 or more and 1 / 20 or less, and even more preferably 1 / 100 or more and 3 / 100 or less.

[0078] (Mineral oil-containing pellet molding process) The mineral oil-containing pellet forming step is a step of forming (preferably compression molding) a mixture of biomass and mineral oil at a predetermined pressure. The mineral oil-containing pellets are formed in the same manner as the biomass pellets of the second embodiment.

[0079] (Heating process) The production method of the third embodiment preferably includes a step of heating the mineral oil-containing pellets obtained in the mineral oil-containing pellet molding step. Specifically, it is preferable to have a step of heating the mineral oil-containing pellets obtained in the mineral oil-containing pellet molding step under conditions of an oxygen concentration of 5 mass % or less and a temperature of 250° C. or more and 350° C. or less. The heating temperature, heating time, heating atmosphere, and oxygen concentration in the heating step are preferably in the same ranges as those described in the second embodiment.

[0080] Other Embodiments The present invention is not limited to the above-described embodiment, and any modifications and improvements that can achieve the object of the present invention are included in the present invention. EXAMPLES

[0081] EXAMPLES Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

[0082] The properties of the black pellets used in the Examples, Comparative Examples, and Reference Examples are shown in Table 1. The properties of the mineral oils 1 to 7 used in the Examples are shown in Table 2. The properties of the IP solvent (isoparaffinic solvent, IP solvent) used in the Reference Examples are shown in Table 3. In Table 1, black pellets are solid fuels made by semi-carbonizing (heating in the absence of oxygen) white pellets made from biomass raw material (acacia wood). The black pellets used in the following examples may be referred to as "BP."

[0083] [Table 1]

[0084] Explanation of Table 1 The total moisture content of black pellets was measured in accordance with ISO 18134-3. The higher heating value and the lower heating value are values ​​measured in accordance with JIS M8814 (2003). "DB" indicates dry basis. "AD" indicates air dry basis. "AR" indicates the arrival base. HGI is the Hardgrove Crushability Index.

[0085] [Table 2]

[0086] Explanation of Table 2 The physical properties in Table 2 were measured by the methods already described.

[0087] [Table 3]

[0088] [Evaluation 1: Coagulation properties of mineral oil against BP fine powder] Example 1-1 In order to keep the proportion of fine powder constant, fine powder and fine pellets were removed in advance from BP (Idemitsu Kosan Co., Ltd., acacia wood) with the properties shown in Table 1 using a dry sieve (mesh opening 6 mm). Then, 0.2 wt% (0.02 g) of fine powder (BP fine powder with a particle size of 0.2 mm or less, actually obtained by dry sieving) was added to BP (10 g), and 1.0 wt% (0.1 g) of mineral oil 1 (Table 2) was further added, and the mixture (BP, fine powder, and mineral oil 1) was shaken to allow the mineral oil 1 to be mixed into the BP and fine powder. The mixture immediately after shaking and the mixture one week after shaking were each observed under a microscope. The results of Example 1-1 are shown in Figures 1A and 1B.

[0089] [Examples 1-2 to 1-7] Except for using mineral oils 2 to 7 shown in Table 2 instead of mineral oil 1 used in Example 1-1, mixtures immediately after shaking and mixtures one week after shaking were prepared in the same manner as in Example 1-1, and these were observed under a microscope. The results of Examples 1-2 to 1-7 are shown in FIGS. 2A to 7A and 2B to 7B, respectively.

[0090] Comparative Example 1-1 A mixture (BP and fine powder) was obtained immediately after shaking in the same manner as in Example 1-1, except that the mineral oil 1 used in Example 1-1 was not added, and then observed under a microscope. The results of Comparative Example 1-1 are shown in FIG.

[0091] Comparative Example 1-2 Except for using distilled water instead of the mineral oil 1 used in Example 1-1, a mixture immediately after shaking and a mixture one week after shaking were prepared in the same manner as in Example 1-1, and these were observed under a microscope. The results of Comparative Example 1-2 are shown in FIG. 9A and FIG. 9B.

[0092] [Reference example 1-1] Except for using IP solvent (Idemitsu Kosan Co., Ltd., Grade 2835) shown in Table 2 instead of mineral oil 1 used in Example 1-1, mixtures immediately after shaking and mixtures one week after shaking were prepared in the same manner as in Example 1-1, and these were observed under a microscope. The results of Reference Example 1-1 are shown in FIG. 10A and FIG. 10B.

[0093] The results of the evaluation of the cohesiveness of mineral oils against fine powders based on the microscopic photographs shown in each figure are summarized in Table 4.

[0094] [Table 4]

[0095] In Examples 1-1 to 1-7 in which mineral oils 1 to 7 were added, the fine powder and mineral oil aggregated in both the mixture immediately after shaking and the mixture one week after shaking. The same results were obtained in Reference Example 1-1 in which IP solvent was added. On the other hand, in Comparative Example 1-2 in which distilled water was added, the fine powder and distilled water did not mix well in the mixture immediately after shaking, and the mixture one week after shaking was in the same state as Comparative Example 1-1 (BP and fine powder only).

[0096] [Evaluation 2: Fine powder abundance ratio F1 and fine powder abundance ratio F2 after mechanical durability test] Example 2-1 In order to keep the proportion of fine powder constant, fine powder and fine pellets were removed in advance from BP having the properties shown in Table 1 using a dry sieve (mesh opening 6 mm). To BP (1.5 kg) having the properties shown in Table 1, 0.5 wt% (7.5 g) of fine powder (BP fine powder with a particle size of 0.85 mm actually obtained by dry sieving) was added, and 1.0 wt% (15 g) of mineral oil 1 (Table 2) was further added by spraying, and the mixture (BP, fine powder, and mineral oil 1) was shaken 30 times to allow the mineral oil 1 to be mixed into the BP and fine powder. The mixture was left to stand for three days after shaking. The mixture (mixture of Example 2-1) three days after shaking was used to measure the fine powder abundance ratio F1 and the fine powder abundance ratio F2 after the mechanical durability test.

[0097] [Examples 2-2 to 2-5] Mixtures (mixtures of Examples 2-2 to 2-5) that had been shaken for 3 days were prepared in the same manner as in Example 2-1, except that mineral oils 2 to 5 shown in Table 2 were used instead of mineral oil 1 used in Example 2-1.

[0098] Comparative Example 2-1 A mixture (mixture of Comparative Example 2-1 (BP and fine powder)) that had been shaken for 3 days was prepared in the same manner as in Example 2-1, except that mineral oil 1 was not added.

[0099] Comparative Example 2-2 A mixture that had been shaken for 3 days (mixture of Comparative Example 2-2) was prepared in the same manner as in Example 2-1, except that distilled water was used instead of the mineral oil 1 used in Example 2-1.

[0100] [Reference example 2-1] A mixture that had been shaken for 3 days (mixture of Reference Example 2-1) was prepared in the same manner as in Example 2-1, except that the IP solvent shown in Table 3 was used instead of the mineral oil 1 used in Example 2-1.

[0101] Here, the multistage sieve 1 used in measuring the fine powder abundance ratio F1 (%) will be described. 11 is a schematic diagram for explaining the multi-stage sieve 1. The multi-stage sieve 1 is provided with, in this order from the side of the tray 10, a sieve 11 with a mesh size of 0.15 mm, a sieve 12 with a mesh size of 0.50 mm, a sieve 13 with a mesh size of 0.85 mm, and a sieve 14 with a mesh size of 3.15 mm. Each sieve is a metal plate sieve with a circular hole diameter. Normally, to measure the fine powder abundance ratio F1, the weight ratio is determined using only a sieve 14 with a mesh size of 3.15 mm. However, in this embodiment, taking into consideration the particle size of the fine powder that actually scatters, the fine powder is divided into particle sizes in a range even finer than 3.15 mm.

[0102] (Fine powder content F1 (%)) The entire amount of the mixture of Example 2-1 was sieved through a multi-stage sieve 1 shown in FIG. In Figure 11, the mass of the fine powder remaining in tray 10 and sieves 11, 12, and 13 was measured to two decimal places, and the fine powder abundance ratio F1 (%) was calculated for each of the particle sizes (1) to (4) below using the following formula (Equation 1). (1) Grain size: over 0.85 mm and under 3.15 mm (2) Grain size: over 0.50 mm and 0.85 mm or less (3) Particle size: over 0.15 mm and not exceeding 0.50 mm (4) Particle size 0.15mm or less

[0103] The fine powder content F1 (%) is the weight ratio (weight %) of each particle size when the weight of particles with a particle size of 3.15 mm or less is taken as 100 weight %. The fine powder content F2 (%) after the mechanical durability test described later is the same. F1=(m1 / m0)×100 (Equation 1) In the above equation (Equation 1), m0 is the total mass (g) of fine powder with a particle size of 3.15 mm or less (fine powder remaining in tray 10 and sieves 11, 12, and 13) after sieving. (1) When calculating the abundance ratio (%) of fine powder having a particle size of more than 0.85 mm and not exceeding 3.15 mm, m1 in the above formula (Equation 1) is the mass (g) of the fine powder remaining on sieve 13 after sieving. (2) When calculating the abundance ratio (%) of fine powder having a particle size of more than 0.50 mm and not exceeding 0.85 mm, m1 in the above formula (Equation 1) is the mass (g) of the fine powder remaining on sieve 12 after sieving. (3) When calculating the abundance ratio (%) of fine powder having a particle size of more than 0.15 mm and not exceeding 0.50 mm, m1 in the above formula (Equation 1) is the mass (g) of the fine powder remaining on sieve 11 after sieving. (4) When calculating the abundance ratio (%) of fine powder having a particle size of 0.15 mm or less, m1 in the above formula (Equation 1) is the mass (g) of the fine powder remaining in the tray 10 after sieving.

[0104] The fine powder abundance ratio F1 (%) was also determined in the same manner as in Example 2-1 for the other example mixtures prepared in Evaluation 2. Figure 12 shows the relationship between the particle size of the BP fine powder and the abundance ratio of the fine powder. In Fig. 12, the notation 0.85-3.15 mm means the particle size range (1) above, the notation 0.5-0.85 mm means the particle size range (2) above, and the notation 0.15-0.50 mm means the particle size range (3) above. The notations in Fig. 13 described below are the same.

[0105] 12, in Examples 2-1 to 2-5 in which mineral oil was added to BP, the abundance ratio F1 (%) of fine powder with a particle size of 0.15 mm or less was significantly smaller than in Comparative Example 2-1 in which no mineral oil was added and Comparative Example 2-2 in which distilled water was added instead of mineral oil. It is believed that the BP fine powder is aggregated by the mineral oil.

[0106] (Fine powder content after mechanical durability test F2 (%)) A mechanical durability test was carried out using the mixture of Example 2-1. The mechanical durability tester will now be described. The rotating box has a smooth steel surface with no gaps. The dimensions of the rotating box are 300mm long x 300mm wide x 125mm deep. - Buffer wings (230mm x 50mm) are attached diagonally inside the rotating box. A sample insertion door is provided on the side of the rotating box. -To rotate the rotating box at a speed of 50 rpm, a rotating shaft is attached at right angles to the wall at the centre of the 300mm x 300mm wall. The durability tester is a twin type, which allows two samples to be measured at the same time.

[0107] (Mechanical durability test) The mixture of Example 2-1 (hereinafter also referred to as Sample A) was used after being thoroughly sieved with a plate sieve with a circular hole diameter (3.15 mm opening). Sample A (500 g) from which fine powder had been thoroughly removed was taken and its mass was measured to two decimal places. Sample A was transferred to the rotating box of a mechanical durability tester, the lid was closed, and the box was rotated exactly 500 times at a rotation speed of 50 rpm. After the rotation was completed, Sample A was removed from the rotating box, and the entire amount of Sample A was sieved through a multi-stage sieve 1 shown in FIG. 11. In Figure 11, the mass of the fine powder remaining in the tray 10 and the sieves 11, 12, and 13 was measured to two decimal places, and using the following formula (Equation 2), the fine powder abundance ratio F2 (%) after the mechanical durability test was calculated for each of the particle sizes (1) to (4) above in the same manner as the fine powder abundance ratio F1 (%). F2 = (n1 / n0) x 100... (Number 2) n0: Total mass (g) of fine powder with a particle size of 3.15 mm or less (fine powder remaining in the tray 10 and sieves 11, 12, and 13) after rotation and sieving n1: Mass (g) of fine powder remaining in the tray 10 and the sieves 11, 12, and 13 after the rotation process and sieving Specifically, n1 in the above formula (Equation 2) is similar to the requirement of m1 in the above formula (Equation 1) in which "after sieving" is replaced with "after rotation processing and sieving."

[0108] For the mixtures of the other examples prepared in Evaluation 2, the abundance ratio F2 (%) of fine powder after the mechanical durability test was determined in the same manner as in Example 2-1. Figure 13 shows the relationship between the particle size of the BP fine powder and the abundance ratio of fine powder after the mechanical durability test. 13, in Examples 2-1 to 2-5 in which mineral oil was added to BP, the abundance ratio F2 (%) of fine powder with a particle size of 0.15 mm or less was significantly smaller even after the mechanical durability test, compared with Comparative Example 2-1 in which no mineral oil was added and Comparative Example 2-2 in which distilled water was added instead of mineral oil. It is believed that the BP fine powder is aggregated by the mineral oil.

[0109] [Evaluation 3: Dust dispersion] Example 3-1 1.0 wt% of mineral oil 1 (Table 2) was added to BP (20 kg) with the properties shown in Table 1, and the mixture (BP and mineral oil 1) was shaken to allow the mineral oil 1 to be spread throughout the BP. The mixture was left to stand for one day after shaking. The mixture was left to stand for three days after shaking. The mixture (mixture of Example 3-1) one day after shaking was used in the drop test.

[0110] Example 3-2 A mixture (mixture of Example 3-2) that had been left for 1 day after shaking was prepared in the same manner as in Example 3-1, except that mineral oil 4 shown in Table 2 was used instead of mineral oil 1 used in Example 3-1.

[0111] Comparative Example 3-1 BP with the properties shown in Table 1 was used in the drop test.

[0112] [Reference example 3-1] A mixture (mixture of Reference Example 3-1) was prepared after shaking for one day in the same manner as in Example 3-1, except that the mineral oil 1 used in Example 3-1 was replaced with the IP solvent shown in Table 3. The total moisture of the mixture of Reference Example 3-1 was 6.9 wt%. The total moisture of the mixture of Reference Example 3-1 was measured in accordance with ISO 18134-3.

[0113] (Drop test) A drop test was conducted using a homemade small dust tester measuring 190 cm high x 90 cm wide x 62 cm deep, using the following method to evaluate dust scattering. A cylindrical member (also called a hopper) with a tapered section was installed on top of the dust tester. The inside diameter (hole diameter) of the tip of the tapered section was 12 cm, and the inside diameter of the cylindrical section was 45 cm. The distance between the tip of the tapered section and the bottom of the dust tester was 160 cm. In addition, a high-volume air sampler was installed 50 cm from the bottom of the dust tester. Details of the high-volume air sampler are described below. The tip of the tapered part was blocked with a removable plate (made of steel), and the mixture of Example 3-1 (hereinafter also referred to as sample B) (20 kg) was introduced from the sample inlet provided at the top of the cylindrical member. After that, the blocked plate was removed, and sample B was allowed to fall naturally from the tip of the tapered part of the cylindrical member into the dust tester for 10 seconds, and at the same time, the high volume air sampler was turned on, and the scattered particles were collected and the amount of dust (g) was measured using the high volume air sampler under the following conditions.

[0114] (conditions) High volume air sampler: HV-500R, manufactured by Shibata Scientific Co., Ltd. Suction pump: Brushless blower Flow rate detection: Differential pressure detection method Suction pressure: -160hPa (500L / min)

[0115] A drop test was also carried out in the same manner as in Example 3-1 for the mixtures of other examples prepared in Evaluation 3. Figure 14 shows the amount of dust (g) scattered during the drop test. 14, in Examples 3-1 and 3-2 in which mineral oil was added to BP, the amount of dispersed dust was significantly less than in Comparative Example 3-1 in which no mineral oil was added. It is believed that the BP fine powder was aggregated by the mineral oil.

[0116] [Evaluation 4: Vapor pressure of mineral oil] 15 shows the vapor pressure curves of water and mineral oil 3. FIG 16 shows the vapor pressure curves of mineral oil 1 and mineral oil 2. 15 and 16, it can be seen that mineral oils 1 to 3 have a significantly lower vapor pressure than water and are less likely to volatilize. In other words, once mineral oil is added to biomass fuel, it becomes unnecessary to add more mineral oil thereafter because the mineral oil is less likely to volatilize, and the dust suppression effect can be maintained for a long period of time. The "coagulation effect of mineral oil on BP fine powder" verified in evaluations 1 to 3 is thought to be due in part to the low volatility of mineral oil. [Industrial Applicability]

[0117] The biomass solid fuel of the present invention is a biomass solid fuel with improved safety because dust scattering is suppressed. This allows the use of biomass solid fuel to be expanded in power plants, steelworks, factories, etc. [Explanation of symbols]

[0118] 1...multi-stage sieve, 10...receiving tray, 11...sieve with 0.15 mm mesh size, 12...sieve with 0.50 mm mesh size, 13...sieve with 0.85 mm mesh size, 14...sieve with 3.15 mm mesh size.

Claims

1. A biomass solid fuel comprising biomass and mineral oil.

2. the biomass is a shaped biomass pellet; At least a portion of the surface of the biomass pellets is coated with the mineral oil. The biomass solid fuel according to claim 1 .

3. The biomass solid fuel is a mineral oil-containing pellet formed from a mixture of the biomass and the mineral oil. The biomass solid fuel according to claim 1 .

4. In the biomass solid fuel, the ratio of the mineral oil to the biomass (the mineral oil / the biomass) is 1 / 1000 or more and 1 / 10 or less in mass ratio. The biomass solid fuel according to claim 1 or 2.

5. The higher heating value on a dry basis is 4500 kcal / kg or more and 6000 kcal / kg or less, and the fuel ratio (fixed carbon / volatile matter) is 0.2 or more and 0.7 or less. The biomass solid fuel according to claim 1 or 2.

6. The hardgrove crushability index (HGI) is 25 or more and 50 or less; The biomass solid fuel according to claim 1 or 2.

7. Bulk density 500 kg / m ３ More than 700kg / m ３ or less, and the mechanical durability is 90% or more and 99% or less, The biomass solid fuel according to claim 1 or 2.

8. The kinematic viscosity of the mineral oil at 40°C is 7mm ２ / s or more 100mm ２ / s or less, The biomass solid fuel according to claim 1 or 2.

9. The flash point of the mineral oil is 150°C or higher and 300°C or lower. The biomass solid fuel according to claim 1 or 2.

10. The density of the mineral oil is 0.8 g / cm ３ 1.0g / cm or more ３ Below is the The biomass solid fuel according to claim 1 or 2.

11. The aniline point of the mineral oil is 90°C or higher and 150°C or lower. The biomass solid fuel according to claim 1 or 2.

12. The average molecular weight of the mineral oil is 250 or more and 600 or less. The biomass solid fuel according to claim 1 or 2.

13. In a ring analysis (ndM method) of the mineral oil in accordance with ASTM D-3238, the weight ratio of the aromatic carbon amount to the total carbon amount is 10% by weight or less, the weight ratio of the naphthenic carbon amount to the total carbon amount is 10% by weight or more and 40% by weight or less, and the weight ratio of the paraffinic carbon amount to the total carbon amount is 50% by weight or more and 90% by weight or less. The biomass solid fuel according to claim 1 or 2.

14. The sulfur content of the mineral oil is 0.15 wt% or less. The biomass solid fuel according to claim 1 or 2.

15. The color (Saybolt) of the mineral oil is -10 or more. The biomass solid fuel according to claim 1 or 2.

16. The biomass is at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass. The biomass solid fuel according to claim 1 or 2.

17. a biomass pellet forming step of forming the biomass into pellets; and coating at least a portion of the surface of the biomass pellets obtained in the biomass pellet molding step with mineral oil. A method for producing biomass solid fuel.

18. The biomass pellets obtained in the biomass pellet molding step are heated under conditions where the oxygen concentration is 5% by mass or less and the temperature is 250°C or higher and 350°C or lower. The method for producing a biomass solid fuel according to claim 17.

19. mixing biomass and mineral oil; and a mineral oil-containing pellet forming step of forming the mixture obtained in the mixing step into pellets. A method for producing biomass solid fuel.

20. a step of heating the mineral oil-containing pellets obtained in the mineral oil-containing pellet molding step under conditions of an oxygen concentration of 5% by mass or less and 250°C or more and 350°C or less. The method for producing a biomass solid fuel according to claim 19.

21. The ratio of the mineral oil to the biomass (the mineral oil / the biomass) is 1 / 1000 or more and 1 / 10 or less by mass ratio, The method for producing a biomass solid fuel according to claim 19 or 20.

22. The biomass is at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass. The method for producing a biomass solid fuel according to claim 19 or 20.

Images