Method for producing biomass coke and biomass coke

Abstract

To provide a method for producing a biomass coke, capable of easily obtaining the biomass coke having sufficient strength by using a plant-derived raw material.SOLUTION: A method according to one embodiment of the disclosure for producing a biomass coke includes: a step of obtaining a mixture that has a plant-crushed material and a binder that contains a plant-derived solvent extract; a step of molding the mixture; and a step of carbonizing the molded product obtained in the molding step.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Coal coke is widely used in foundry furnaces, blast furnaces, etc. In recent years, with the growing demand for the creation of a recycling-oriented society, there has been a desire to move away from fossil fuels, as in the energy field, and the use of biomass has attracted attention. A method for producing coke using biomass is known (Japanese Patent Laid-Open Publication No. 2024-25561). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-25561 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes a method for producing coke with sufficient strength for use in blast furnaces by mixing and pulverizing torrefied biomass and coal and molding the resulting powder mixture, and claims that using this coke can reduce carbon dioxide emissions derived from fossil fuels. However, using biomass as part of the raw material for coke may not be enough to achieve carbon neutrality, and there is a need to further reduce carbon dioxide emissions derived from fossil fuels.

[0005] In view of the above-mentioned circumstances, an object of the present disclosure is to provide a method for producing biomass coke that can easily obtain biomass coke having sufficient strength using plant-derived raw materials. [Means for solving the problem]

[0006] A method for producing biomass coke, which is one aspect of the present disclosure for solving the above problems, includes a step of obtaining a mixture containing crushed plant material and a binder containing a plant-derived solvent extract, a step of molding the mixture, and a step of dry distilling the molded product formed in the molding step. [Effects of the Invention]

[0007] This method for producing biomass coke makes it easy to obtain biomass coke with sufficient strength using plant-derived raw materials. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a graph showing the relationship between the binder blending ratio and tensile strength in biomass cokes of Test Examples 1 to 12 of the Examples. [Figure 2] FIG. 2 is a graph showing the relationship between the binder blending ratio and bulk density in the biomass coke of FIG. [Figure 3] FIG. 3 is a graph showing the relationship between the binder blending ratio and tensile strength in the biomass cokes of Test Examples 1 to 6 and Test Examples 14 to 16 of the Examples. [Figure 4] FIG. 4 is a graph showing the relationship between the binder blending ratio and bulk density in the biomass coke of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) A method for producing biomass coke, which is one aspect of the present disclosure, includes a step of obtaining a mixture containing crushed plant material and a binder containing a plant-derived solvent extract, a step of molding the mixture, and a step of dry distilling the molded product obtained in the molding step.

[0011] This biomass coke production method involves molding and carbonizing a mixture of crushed plant material and a binder containing a plant-derived solvent extract, thereby easily obtaining biomass coke without the need for complicated processes such as semi-carbonization. The use of crushed plant material and a binder containing a plant-derived solvent extract allows the biomass coke obtained to have sufficient strength and an improved bulk density.

[0012] (2) In the above (1), the amount of the binder added to 100 parts by mass of the crushed material in the step of obtaining the mixture may be 45 parts by mass or less. By adding 45 parts by mass or less of the binder to 100 parts by mass of the crushed material, it is possible to improve the ease of achieving the desired strength and bulk density of the obtained biomass coke.

[0013] (3) In the above (1) or (2), the particle size of the crushed material may be 500 μm or less (30 mesh pass). By making the particle size of the crushed material 500 μm or less, the strength and bulk density of the obtained biomass coke can be further improved.

[0014] (4) In any of (1) to (3), the solvent extract may be derived from rice husks. By using a binder containing a solvent extract derived from rice husks, the strength and bulk density of the resulting biomass coke can be further improved.

[0015] (5) In any one of (1) to (4), the tensile strength of the dry distillate obtained in the dry distillation step is 3.0 MPa or more and the bulk density is 0.75 g / cm 3 The dry distillate may have a tensile strength of 3.0 MPa or more and a bulk density of 0.75 g / cm 3 As a result of these properties, the coke can be used as foundry coke, blast furnace coke, etc.

[0016] (6) Biomass coke according to one embodiment of the present disclosure comprises crushed plant material and a binder containing a plant-derived solvent extract.

[0017] Since the biomass coke contains crushed plant material and a binder containing a plant-derived solvent extract, it has sufficient strength and bulk density and can be easily produced.

[0018] [Details of the Mode for Carrying Out the Disclosure] An example of an embodiment of the present disclosure will be described in detail below.

[0019] A method for producing biomass coke (hereinafter simply referred to as the production method) that is one embodiment of the present disclosure includes a step of obtaining a mixture containing crushed plant material and a binder containing a plant-derived solvent extract, a step of molding the mixture, and a step of dry distilling the molded product formed in the molding step.

[0020] The plant material used as the crushed material is not particularly limited, but is preferably a woody material (biomass), more preferably a biomass of coniferous trees such as cedar, cypress, etc. Woody biomass may also be waste materials such as construction waste and paper waste.

[0021] The means for crushing the plant material is not particularly limited, and for example, a known crusher such as a cutter mill or a hammer mill may be used.

[0022] The binder used in the biomass coke production method includes a plant-derived solvent extract. The plant used as the raw material for the solvent extract is not particularly limited and may be a woody plant (tree), but is preferably a herbaceous plant (flowering plant). The herbaceous plant may be agricultural waste, etc. The parts of the herbaceous plant used as the raw material may be any one or a combination of two or more of the roots, stems, leaves, fruits, and husks, but it is preferable to use husks, and especially rice husks.

[0023] The method for obtaining the binder is not particularly limited and may be a known method. Specifically, for example, the binder may be obtained by a procedure of removing moisture from the plant that is the raw material for the solvent extract, mixing the dehydrated plant with a predetermined solvent and heating the mixture, performing solid-liquid separation after heating to obtain an extract containing the solvent extract, and removing unnecessary components by heating the extract. The predetermined solvent is not particularly limited and may be, for example, a bicyclic aromatic compound such as 1-methylnaphthalene.

[0024] <Step of Obtaining a Mixture> The mixture may be obtained, for example, by putting the crushed material and the binder into a tank (container) and stirring, etc. The crushed material may be dried by air drying or the like before or after crushing to reduce the moisture content (water content).

[0025] The upper limit of the particle size of the crushed material (the maximum particle size of the crushed material) is preferably 500 μm, more preferably 300 μm, and even more preferably 200 μm. By setting the particle size of the crushed material in the mixture to the upper limit or less, the strength of the biomass coke obtained by the production method can be improved, while also improving ease of handling and reducing costs. The lower limit of the particle size of the crushed material is not particularly limited and may be, for example, 3 μm, 5 μm, 8 μm, or 10 μm.

[0026] In the mixture, the upper limit of the amount of binder added per 100 parts by mass of the crushed material is preferably 45 parts by mass, more preferably 40 parts by mass, and even more preferably 38 parts by mass. The lower limit of the amount added is not particularly limited and may be 1 part by mass or 3 parts by mass. By setting the amount added within the above range, the strength of the biomass coke can be made sufficient.

[0027] <Molding process> The mixture may be molded, for example, using a known pelletizer, mold, etc. The shape of the molded product is not particularly limited, and may be a cylindrical shape, a polygonal columnar shape, a sphere, an oval sphere (spindle shape), a rectangular parallelepiped shape, or a three-dimensional shape with an irregular surface.

[0028] The mixture may be formed by cold forming or hot forming. The upper limit of the forming temperature of the mixture in the hot forming is not particularly limited and may be, for example, 200°C, 190°C, or 180°C. The lower limit of the forming temperature is not particularly limited and may be, for example, 80°C, 100°C, or 120°C. Forming the mixture at a temperature within the above range can improve the reliability of obtaining biomass coke having the desired strength and bulk density.

[0029] The upper limit of the pressure to be applied when molding the mixture is not particularly limited and may be, for example, 200 MPa, 180 MPa, or 150 MPa. The lower limit of the pressure is not particularly limited and may be, for example, 70 MPa, 80 MPa, or 90 MPa. Applying a pressure within the above range to the mixture can further increase the reliability of obtaining a biomass coke having the desired strength and bulk density.

[0030] <Dry distillation process> The dry distillation of the molded product may be carried out using, for example, a known drying oven, etc. When using a drying oven, etc., it is advisable to create a reducing atmosphere in the oven with nitrogen gas or the like.

[0031] The upper limit of the temperature for carbonizing the formed product is not particularly limited and may be, for example, 1300°C, 1250°C, or 1200°C. The lower limit of the temperature is not particularly limited and may be, for example, 500°C, 700°C, or 800°C. Carbonizing the formed product at a temperature within the above ranges can further improve the reliability of obtaining biomass coke having the desired strength and bulk density.

[0032] The lower limit of the tensile strength of the carbonized product (biomass coke) obtained in the carbonization step is preferably 3.0 MPa, more preferably 4.0 MPa, and even more preferably 5.0 MPa. The upper limit of the tensile strength is not particularly limited and may be, for example, 30.0 MPa. The lower limit of the bulk density of the carbonized product is 0.75 g / cm. 3 is preferred, and 0.80 g / cm 3 More preferably, 0.85 g / cm 3 The upper limit of the bulk density of the dry distillate is not particularly limited, and is, for example, 1.5 g / cm 3 The biomass coke has a tensile strength within the above range and a bulk density within the above range, and therefore can be suitably used as foundry coke or blast furnace coke.

[0033] [Other embodiments] The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as falling within the scope of the present invention. [Example]

[0034] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to these examples.

[0035] Air-dried Japanese cedar was ground in a cutter mill to obtain cedar chips with a particle size of less than 106 μm (150 mesh pass). The moisture content of these cedar chips was 7% by mass or more and 9% by mass or less.

[0036] 800g of dehydrated rice husks and 3200g of 1-methylnaphthalene were placed in an autoclave, and the autoclave was replaced with nitrogen (atmospheric pressure). The autoclave was then heated to 350°C for 60 minutes, and the solvent-insoluble matter was removed by filtration to recover the rice husk solvent extract (extract). The solvent with a boiling point of 240°C or less was removed from the recovered extract by distillation to obtain the binder.

[0037] The cedar chips and the binder were placed in a container (0.25 L) and mixed for 2 hours at 150 rpm using a rotating table (BALL MIL ANZ-61S, manufactured by Nitto Kagaku Co., Ltd.) to obtain a mixture. In order to maintain the particle size of the cedar chips, no grinding balls were placed in the container.

[0038] 1 g of the mixture was filled into a cylindrical mold (inner diameter: 14.1 mm), and pressure of 128 MPa (approximately 1.3 t / cm) was applied in the axial direction of the cylindrical mold. 2 ) for 8 minutes to obtain cold-formed products for Test Examples 1 to 6.

[0039] 1 g of the mixture was filled into the cylindrical mold, and the cylindrical mold was placed in a press heated to 140°C and left for 30 minutes without applying any load. After that, a load of 128 MPa was applied in the axial direction of the cylindrical mold for 8 minutes to obtain hot-molded products for Test Examples 7 to 13.

[0040] The above cold-formed and hot-formed products were placed on quartz glass and carbonized in an electric tubular furnace (ARF-30KC, manufactured by Asahi Rika Seisakusho Co., Ltd.) by heating up to 1000°C at a rate of 5°C / min under a nitrogen stream (300 mL / min) and holding the temperature for 10 minutes, and then cooled to room temperature to obtain biomass cokes of Test Examples 1 to 13.

[0041] The cedar was crushed to a size of 1000 μm or more and 2000 μm or less, and the crushed cedar was used to obtain the biomass cokes of Test Examples 14 to 16. The mixing, molding, and carbonization of the biomass cokes of Test Examples 14 to 16 were carried out in the same manner as for the biomass cokes of Test Examples 1 to 6.

[0042] The diameter, height (axial length), and dry mass of the biomass coke after carbonization were measured. The tensile strength of the biomass coke was evaluated by an indirect tensile test using a precision universal testing machine (EZ-L, manufactured by Shimadzu Corporation). The measurement was performed by sandwiching the cylindrically formed biomass coke between two plates so that the side of the biomass coke was in contact with the surface of the two plates, and then displacing one plate toward the other to apply a load. The load basically increases linearly and decreases rapidly when the biomass coke breaks. The load at which this breakage occurs is called the maximum load L max The tensile strength Ts [MPa] was calculated using the following formula 1, where [N] is the strain rate. Ts = 2L max / πdl ····(1) In the above formula 1, "d" means the diameter of the biomass coke [mm], and "l" means the axial height of the biomass coke [mm].

[0043] The bulk density was calculated from the measured dry mass, diameter, and height of the biomass coke. Note that in Test Example 6, in which the binder content was 50 mass% and cold-formed, the biomass coke expanded and deformed, making it impossible to measure the average diameter and height. Therefore, the bulk density was calculated assuming a cylindrical shape with the maximum diameter and maximum height that could be measured.

[0044] Table 1 shows the binder blending ratio (addition ratio) relative to the total mass of the cedar chips or pulverized cedar material, as well as the tensile strength and bulk density for each test example. Note that a "-" in Table 1 indicates that measurement or calculation was not possible. FIG. 1 shows a graph illustrating the relationship between binder blending ratio and tensile strength for test examples 1 to 12, and FIG. 2 shows a graph illustrating the relationship between binder blending ratio and bulk density for test examples 1 to 5 and 14 to 16. FIG. 3 shows a graph illustrating the relationship between binder blending ratio and tensile strength for test examples 1 to 5 and 14 to 16, and FIG. 4 shows a graph illustrating the relationship between binder blending ratio and bulk density.

[0045] [Table 1]

[0046] Test Example 1, in which no binder was added during cold compaction, and Test Example 6, in which a binder was added at 50% by mass, failed to achieve sufficient tensile strength and bulk density, indicating that they are unsuitable for use as coke for castings. Test Example 13, in which a binder was added at 50% by mass during hot compaction, failed to maintain the shape (formed shape) required for biomass coke. As a result, it was not possible to measure the diameter and height, and it was not possible to calculate the tensile strength and bulk density. Furthermore, it was found that even when the binder content was greater than 0% by mass and less than 50% by mass, the biomass cokes of Test Examples 14 to 16, obtained using the crushed cedar material with large particle sizes, did not achieve sufficient tensile strength and bulk density.

[0047] The biomass cokes of Test Examples 2 to 5 and Test Examples 7 to 12, which were obtained by blending cedar chips crushed to an appropriate particle size (less than 106 μm in this example) with an appropriate amount of binder (less than 50% by mass in this example), were able to achieve tensile strength and bulk density sufficient for use as coke for casting, etc. That is, the biomass coke can achieve sufficient tensile strength and bulk density whether cold-formed or hot-formed. Comparing Test Examples 2 to 4 and Test Examples 7 to 9, which contain binder content of less than 30% by mass, shows that hot-formed cokes can improve tensile strength. In other words, when the binder content is less than 30% by mass, hot-formed cokes can achieve sufficient tensile strength and bulk density with a smaller amount of binder. [Industrial Applicability]

[0048] The biomass coke manufacturing method disclosed herein can produce coke with sufficient strength and bulk density, making it suitable for use in sites such as pig iron production, and because it uses raw materials derived from plants, it can contribute to carbon neutrality.

Claims

1. obtaining a mixture comprising crushed plant material and a binder comprising a plant-derived solvent extract; shaping the mixture; a step of dry distilling the molded product obtained in the molding step; A method for producing biomass coke comprising:

2. The method for producing biomass coke according to claim 1, wherein the amount of the binder added per 100 parts by mass of the crushed material in the step of obtaining the mixture is 45 parts by mass or less.

3. The method for producing biomass coke according to claim 1, wherein the particle size of the crushed material is 500 μm or less.

4. The method for producing biomass coke according to claim 1, wherein the solvent extract is derived from rice husks.

5. The tensile strength of the dry distillate obtained in the dry distillation step is 3.0 MPa or more and the bulk density is 0.75 g / cm ３ The method for producing biomass coke according to any one of claims 1 to 4.

6. Biomass coke comprising crushed plant material and a binder containing a plant-derived solvent extract.

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