Method for producing bio-formed coke

Abstract

To provide a method for producing bio-formed coke that can obtain bio-formed coke with high calorific value and strength.SOLUTION: A method for producing bio-formed coke 23 comprises: a mixing step of mixing a palm shell material (biomass feedstock 21), which is a palm shell or palm shell charcoal from which impurities have been removed, with a binder 22 using a mixer 13 to obtain a mixture; a molding step of pressure-molding the mixture using a molding machine 14 to obtain a molded body; and a heating step of heating the molded body in a non-oxidative atmosphere using a heating furnace 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing bio-molded coke, and more particularly to a technology for producing bio-molded coke that can be a substitute for coal coke using biomass raw materials. [Background technology]

[0002] In order to achieve the carbon neutral goal, there is a need to develop and put into practical use technologies to reduce CO2 emissions. For example, cupola furnaces used in the casting manufacturing process are furnaces that use coal coke, which is made from coal, as a heat source to melt iron and other materials. In order to achieve carbon neutrality in the future, it is hoped that the heat source for cupola furnaces will be replaced from fossil fuel-derived coal coke to carbon-neutral fuels.

[0003] In the midst of such a trend, in recent years, various techniques have been proposed for producing molded coke that can be used as an alternative to coal coke using biomass raw materials (see, for example, Patent Document 1 and Patent Document 2). Patent Document 1 discloses that biomass raw materials such as cedar sawdust and cypress bark are crushed, then filled into a cylinder, and molded under pressure while heating, thereby pyrolyzing hemicellulose out of lignin, cellulose, and hemicellulose, which are the main components of the biomass raw materials, and reacting at a low temperature while maintaining the skeletons of cellulose and lignin, and then cooling and drying to produce a biomass solid with a maximum compressive strength of 60 to 200 MPa and a calorific value of 18 to 23 MJ / kg. In this Patent Document 1, hemicellulose contained in the biomass raw material is pyrolyzed to exhibit an adhesive effect, and cellulose and lignin are consolidated while maintaining their skeletons, thereby obtaining a biomass solid before or after semi-carbonization.

[0004] Patent Document 2 discloses a method for producing coke using lignite, which is less expensive than raw coal, by mixing lignite and plant-derived biomass, hot-molding the mixture, and then coking it. In the method described in Patent Document 2, an appropriate amount of plant-derived biomass is blended with lignite, which has a low aliphatic carbon content, to improve the strength of molded coke made from lignite and also to reduce CO2 emissions when using the coke. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2006 / 078023 [Patent Document 2] JP 2019-199567 A Summary of the Invention [Problem to be solved by the invention]

[0006] The biomass solids in Patent Document 1 are in a pre-semi-carbonized or semi-carbonized state, so the proportion of fixed carbon is low, and it is considered that the calorific value and strength are insufficient compared to coal coke. In addition, the coke in Patent Document 2 is mainly composed of lignite, so it has lower strength compared to coal coke obtained using raw coal, and there is also room for further improvement from the viewpoint of carbon neutrality.

[0007] In the casting manufacturing process, coke is charged from the top of the cupola, and the charged coke descends inside the furnace to be used as a heat source for producing molten metal at the bottom of the furnace. If the strength of the coke is insufficient for such purposes, the coke charged from the top of the furnace may break before reaching the bottom of the furnace. In this case, there is a concern that the quality of the molten metal obtained may be unstable.

[0008] The present invention has been made in consideration of the above problems, and has as its main object to obtain a bio-molded coke having a high calorific value and strength. [Means for solving the problem]

[0009] According to the present invention, the following means are provided. [1] A method for producing bio-molded coke, comprising: a mixing step of mixing coconut shell material, which is coconut shell or coconut shell charcoal from which impurities have been removed, with a binder to obtain a mixture; a molding step of pressurizing and molding the mixture to obtain a molded body; and a heating step of heating the molded body in a non-oxidizing atmosphere. [2] The method for producing bio-molded coke according to [1] above, wherein the blending ratio of the binder to the coconut shell material is 5% by mass or more and 30% by mass or less. [3] The method for producing bio-molded coke according to [1] or [2] above, wherein the coconut shell material has an average particle size of 10 μm or more and 1,000 μm or less. [4] The method for producing a bio-molded coke according to any one of [1] to [3] above, wherein in the molding step, the mixture is pressure molded while being heated in the atmosphere to obtain the molded body. [5] The method for producing bio-molded coke according to [4], wherein in the heating step, the molded body is heated at a temperature higher than the heating temperature in the molding step. [6] The method for producing bio-molded coke according to any one of [1] to [5] above, wherein the heating temperature in the heating step is 300° C. or higher and 2,000° C. or lower. [7] The method for producing biomolded coke according to any one of [1] to [6] above, wherein the binder is coal tar pitch, asphalt pitch, wood tar, cement, bentonite, water glass, raw coal, caking coal, or a combination of two or more of these. Effect of the Invention

[0010] According to the manufacturing method of the present invention, coconut shells or coconut shell charcoal from which impurities have been removed are mixed with a caking material, and the mixture is pressurized and molded into a molded body, which is then heated in a non-oxidizing atmosphere to obtain a bio-molded coke with a high calorific value and high strength. [Brief description of the drawings]

[0011] [Figure 1] Schematic diagram of a bio-molded coke production system. [Diagram 2] FIG. 2 is a graph showing the measurement results of the calorific values ​​of bio-molded coke and coal coke. [Diagram 3] FIG. 2 is a graph showing the measurement results of the strength of bio-molded coke and coal coke. [Figure 4] FIG. 1 is a graph showing the change in molten metal temperature when molten metal is produced using bio-molten coke as part of the fuel. [Diagram 5] This is a diagram showing the change in molten metal composition (component C) when molten metal is produced using bio-molten coke as part of the fuel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Matters related to the present disclosure will be described in detail below. The manufacturing method of the present disclosure (hereinafter also referred to as the present manufacturing method) is to manufacture bio-molded coke using a raw material derived from palm kernel shell (PKS) by a method including a mixing step, a molding step, and a heating step as described below. Mixing step: The coconut shell or coconut shell charcoal from which impurities have been removed is mixed with a binder to obtain a mixture. Molding process: The mixture of coconut shell material and binder is pressurized and molded to obtain a molded body. Heating step: The molded body is heated in a non-oxidizing atmosphere.

[0013] The biomolded coke obtained by this manufacturing method is a coke (skeletal coke) produced from biological resources as a raw material, and can also be called "biomolded charcoal". In this manufacturing method, impurities are removed from the biomass raw material coconut shell or coconut shell charcoal, and then pressure molding is performed, so that a compact molded body with low porosity can be obtained. In addition, by further heating the obtained molded body in a non-oxidizing atmosphere, a biomolded coke with improved strength can be obtained. Such a biomolded coke obtained by this manufacturing method is useful as a substitute for coal coke. Each step will be described below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0014] <Mixing process> In this production method, coconut shells or coconut shell charcoal from which impurities have been removed (hereinafter also referred to as "coconut shell material") is used as a biomass raw material. Examples of impurities include stones, branches, garbage, metal pieces, moisture, and volatile matter. Methods for removing impurities from coconut shells or coconut shell charcoal include sieve separation, magnetic separation, heating, and the like. For example, sieve separation can remove relatively large solids such as stones, branches, and garbage contained in coconut shells or coconut shell charcoal. In addition, magnetic separation can remove metal pieces contained in coconut shells or coconut shell charcoal, and heat treatment can remove moisture and volatile matter. Coconut shell charcoal from which impurities have been removed is preferably used as a raw material for this production method, since it is possible to obtain a biomolded coke with a higher calorific value and strength.

[0015] In addition, the coconut shell or coconut shell charcoal after the impurities are removed may contain impurities to the extent that a biomolded coke having a desired calorific value and strength can be obtained. Specifically, the coconut shell or coconut shell charcoal after the impurities are removed (i.e., coconut shell material) may contain impurities in a range of, for example, 7% by mass or less, or 5% by mass or less.

[0016] The coconut shell material used for mixing with the binder is preferably particulate. The average particle size of the coconut shell material is preferably 10 μm or more and 1,000 μm or less, in order to reduce the porosity of the molded body obtained in the next molding step as much as possible and obtain a bio-molded coke with a higher calorific value and higher strength. From the above viewpoint, the average particle size of the coconut shell material is more preferably 700 μm or less, and even more preferably 500 μm or less. On the other hand, from the viewpoint of the handleability of the coconut shell material, the average particle size of the coconut shell material is more preferably 50 μm or more, and even more preferably 100 μm or more. In this specification, the average particle size of the coconut shell material is a value measured by laser diffraction.

[0017] By providing a processing step such as crushing, pulverization, or grinding (hereinafter also referred to as a "grinding step"), particulate coconut shell material can be obtained. In this case, the grinding process may be performed before or after removing impurities from the coconut shell or coconut shell charcoal. Moreover, the grinding process may be performed before or after removing impurities. The method of the grinding process is not particularly limited, and it can be performed using a known grinder or crusher. For example, the coconut shell or coconut shell charcoal is ground before or after removing impurities using various grinding media such as iron bars, iron balls, and aluminum balls.

[0018] The binder may be any material capable of functioning as a binder for obtaining a molded body mainly composed of coconut shell material. For example, the binder may be solid or liquid, and may be an inorganic or organic binder. Specific examples of the binder include coal tar pitch, asphalt pitch, wood tar, cement, bentonite, water glass, raw coal or caking coal, or a combination of two or more of these. In terms of being able to obtain a highly durable biomolded coke, the binder is preferably coal tar pitch, asphalt pitch, wood tar, cement, bentonite or water glass, or a combination of two or more of these, more preferably coal tar pitch, asphalt pitch or wood tar, or a combination of two or more of these, and even more preferably coal tar pitch.

[0019] When the binder is solid, it is preferable that the binder is particulate. From the viewpoint of obtaining a biomolded coke with improved calorific value and strength, the average particle size of the binder is preferably 5 μm or more and 1,000 μm or less. From the above viewpoint, the average particle size of the binder is more preferably 700 μm or less, and even more preferably 500 μm or less. Furthermore, from the viewpoint of the handleability of the binder, the average particle size of the binder is more preferably 30 μm or more, and even more preferably 50 μm or more. In this specification, the average particle size of the binder is a value measured by laser diffraction.

[0020] It is preferable that the coconut shell material and the binder used in the mixing step have the same average particle size. Specifically, the ratio (D2 / D1) of the average particle size D2 of the binder to the average particle size D1 of the coconut shell material is preferably 0.9 to 1.1, and more preferably 0.95 to 1.05.

[0021] The method of mixing the coconut shell material and the binder is not particularly limited. Examples of the method of mixing the coconut shell material and the binder include a drum rotation method, a blade rotation method, and a steam mixing method. The coconut shell material and the binder may be mixed at room temperature or with heating. The coconut shell material and the binder may be mixed with water added or with steam heating. When the coconut shell material and the binder are mixed with heating, the heating temperature is preferably in the range of 30° C. or more and 150° C. or less. The coconut shell material and the binder are usually mixed at normal pressure, but may be mixed with pressure.

[0022] The blending ratio of the binder to the coconut shell material is preferably 5% by mass or more and 30% by mass or less. By setting the blending ratio of the binder to the coconut shell material in the above range, the moldability of the mixture of the coconut shell material and the binder can be improved. From this viewpoint, the blending ratio of the binder to the coconut shell material is more preferably 10% by mass or more, and further preferably 15% by mass or more. The upper limit of the blending ratio of the binder to the coconut shell material is more preferably 25% by mass or less.

[0023] In the mixture of coconut shell material and the binder, the proportion of coconut shell material is preferably 65 mass % or more, and more preferably 70 mass % or more, based on the total amount of the mixture.

[0024] When producing a mixture of coconut shell material and a binder, components other than the coconut shell material and the binder (hereinafter, also referred to as "other components") may be further blended. Examples of other components include metal particles (Fe, Cu, Mn, Ni, P, etc.) and natural sulfur. The blending amount of other components may be appropriately set within a range that does not impair the effects of the present invention.

[0025] <Molding process> In the molding step, the mixture of coconut shell material and binder obtained in the mixing step is pressure molded to obtain a molded body. The molding method is not particularly limited, and can be appropriately performed using a known molding device. Examples of molding methods include a horizontal press method, a vertical press method, and a roll press method. The pressure during pressure molding is preferably in the range of 5 MPa to 50 MPa, more preferably in the range of 5 MPa to 45 MPa, and even more preferably in the range of 10 MPa to 45 MPa. The pressurization time is about 1 second to 30 minutes.

[0026] The mixture may be molded while being heated. In terms of being able to obtain a molded body having a low porosity and a high density, it is preferable to pressure mold the mixture while being heated in the atmosphere in the molding step to obtain a molded body.

[0027] When molding the mixture while heating it, the temperature is preferably in the range of 30° C. or more and 300° C. or less. The heating temperature during molding is preferably 50° C. or more, more preferably 70° C. or more, from the viewpoint of filling the spaces between the coconut shell particles with the binder to increase the shape stability of the molded body and obtaining a denser bio-molded coke. The upper limit of the heating temperature is preferably 250° C. or less, more preferably 230° C. or less, from the viewpoint of suppressing the volatilization of the binder and increasing moldability.

[0028] The shape and size of the molded body are not particularly limited and are appropriately set depending on the application of the biomolded coke. For example, the cross-sectional shape of the molded body can be a circle, a square, a triangle, a hexagon, or the like. The molded body may also be a structure having a hollow structure. As a specific example of the shape and size of the molded body, when the biomolded coke obtained by the present production method is applied to coke for casting, the molded body may be a cylindrical structure having a diameter of about 5 to 200 mm and a height of about 5 to 500 mm.

[0029] The molded body obtained in the molding step is preferably cooled to room temperature and then heated in the next heating step in order to prevent cracks, etc. The molded body may be cooled by standing to cool, or may be cooled using a cooling means (for example, a cooling medium or a cooling device).

[0030] <Heating process> In the heating step, the molded body obtained in the molding step is heated (coked) in a non-oxidizing atmosphere, which can further increase the strength of the bio-molded coke.

[0031] In the heating step, the method for heating the molded body is not particularly limited. Examples of the method for heating the molded body include an electric heater method and a gas burner method.

[0032] The non-oxidizing atmosphere may be an inert gas atmosphere such as nitrogen gas, argon gas, or helium gas, or a reducing atmosphere such as hydrogen-containing nitrogen gas. The non-oxidizing atmosphere may also be realized by a vacuum atmosphere. Of these, a nitrogen gas atmosphere is preferably used because it is easy to handle and inexpensive. The "non-oxidizing atmosphere" may contain oxygen to the extent that the molded body containing coconut shell material can be coked. Specifically, for example, the oxygen may be contained in a range of 5% by volume or less, 3% by volume or less, or 1% by volume or less.

[0033] The heating temperature of the molded body in the heating step is preferably 300° C. or more and 2,000° C. or less. From the viewpoint of further increasing the strength of the biomolded coke, the heating temperature in the heating step is more preferably 400° C. or more, and even more preferably 500° C. or more. From the viewpoint of reducing energy consumption and equipment, the heating temperature in the heating step is more preferably 1,800° C. or less, and even more preferably 1,500° C. or less. When molding the mixture while heating in the molding step, it is preferable to heat the molded body in this heating step at a temperature higher than the heating temperature during molding.

[0034] The heating rate when increasing the ambient temperature of the molded body to a desired temperature is preferably about 0.1 to 10°C / min from the viewpoint of suppressing cracking of the molded body and improving productivity. The heating time of the molded body (specifically, the total of the temperature increase time and the holding time) is preferably about 30 minutes to 24 hours.

[0035] Next, a bio-molded coke production system will be described with reference to Fig. 1. Fig. 1 shows an example of a schematic configuration of a production system used to produce bio-molded coke by the present production method. The production system 10 in Fig. 1 includes a pulverizer 11, a mixer 13, a molder 14, and a heating furnace 15.

[0036] 1, first, coconut shells or coconut shell charcoal (i.e., coconut shell material) from which impurities have been removed is fed into a crusher 11 as biomass raw material 21, and crushed to a desired size (crushing step). Note that if the coconut shell material obtained is in particulate form, the crushing process by the crusher 11 may be omitted.

[0037] The crushed coconut shell material is fed into a mixer 13 together with a binder 22, and mixed by the mixer 13 (mixing process). FIG. 1 shows a case in which a tank 12 for storing the binder 22 is provided in the manufacturing system 10, and the binder 22 is supplied from the tank 12 to the mixer 13. The method of feeding the crushed coconut shell material and the binder 22 into the mixer 13 is not particularly limited, and can be appropriately performed by a method of feeding them all at once, a method of feeding them in portions, a method of feeding them continuously, or the like. Moreover, the crushed coconut shell material and the binder 22 may be fed into the mixer 13 at the same time, or may be fed separately.

[0038] The mixture of coconut shell material and binder 22 mixed by mixer 13 is fed into molding machine 14 and molded under pressure (molding process). Although a horizontal press type device is shown as molding machine 14 in FIG. 1, a vertical press type device may also be used. The molded body molded under pressure by molding machine 14 is then transported to heating furnace 15 and heated (coked) in a non-oxidizing atmosphere. As a result, biomolded coke 23 is obtained.

[0039] <Use of bio-molded coke> The biomolded coke obtained by the present production method has a high calorific value and strength. Examples of applications of such biomolded coke include foundry coke, blast furnace coke, and general coke. The biomolded coke obtained by the present production method can exhibit a high calorific value of, for example, 25 MJ / kg or more, and even 28 MJ / kg or more, and also has high strength. Such biomolded coke is particularly useful as a heat source for a cupola, which is a furnace for melting iron and the like in the production of castings, i.e., as foundry coke. EXAMPLES

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the following, "%" is based on mass unless otherwise specified.

[0041] [Example 1] 1. Production of bio-molded coke Coconut shell charcoal from which impurities (pebbles, branches, trash, metal pieces, moisture, and volatile matter) had been removed was used as a biomass raw material to produce biomolded coke. First, the coconut shell charcoal from which impurities had been removed was pulverized to an average particle size of 300 μm using a pulverizer (manufactured by Chuo Kakoki Co., Ltd., method: pulverization method, pulverization medium: iron bar) (pulverization process). The average particle size of the pulverized coconut shell charcoal was measured using a laser diffraction particle size distribution measuring device. Next, the pulverized raw material and coal tar pitch (average particle size 300 μm) as a binder were put into a mixer (manufactured by Tombo Kogyo Co., Ltd., method: blade rotation method) in a blending ratio such that the binder was 20 mass% relative to the pulverized raw material, and thoroughly mixed (mixing process). The mixture thus obtained was compressed and pressed using a molding machine (manufactured by Naniwa Roki Co., Ltd., type: horizontal press type, briquette size: diameter 125 mm) under conditions of a pressure of 20 MPa, a pressing time of 5 minutes, and a heating temperature of 150°C to obtain a molded body (molding process). Next, the molded body was placed in a heating furnace (manufactured by Narita Techno Co., Ltd., type: gas burner type) and fired in a nitrogen atmosphere under conditions of a heating temperature of 1,200°C, a heating rate of 2°C / min, and a holding time of 12 hours to obtain a biomolded coke.

[0042] 2. Evaluation The quality characteristics were evaluated for the biomolded coke of Example 1. The evaluation items, evaluation methods, and results are as follows. (1) Heat generation The calorific value of the biomolded coke was measured according to JIS M8814:2003. A calorific value of 28 MJ / kg or more is considered to be highly practical. As a result, the calorific value of the biomolded coke of Example 1 was 31 MJ / kg, which was equal to or higher than that of the coal coke (Reference Example 1) (FIG. 2). (2) Strength The strength of the biomolded coke was measured by a drop test in accordance with JIS K2151:2004. The strength is expressed as an index, and an index of 95 or more is considered to be highly practical. As a result, the strength (index) of the biomolded coke of Example 1 was 98, which was equivalent to that of coal coke (Reference Example 1) (FIG. 3). (3) Cupola Demonstration Test In a cupola owned by Aisin Takaoka Co., Ltd., casting materials (pig iron, steel scrap, return material) were melted using fuel in which 20% of coal coke was replaced with the bio-molded coke of Example 1 as a heat source, and the molten metal temperature and molten metal composition (carbon (C) content) were measured approximately every 15 minutes. The results are shown in Figures 4 and 5. In Figures 4 and 5, the horizontal axis indicates the elapsed time [H].

[0043] As a result, even when part of the fuel was replaced with the bio-molten coke of Example 1, the molten metal temperature and composition remained stable over time (Figures 4 and 5), and it was confirmed that they were equivalent to those during normal operation when 100% coal coke was used as fuel. [Explanation of symbols]

[0044] 10... manufacturing system, 11... pulverizer, 12... tank, 13... mixer, 14... molding machine, 15... heating furnace, 21... biomass raw material (coconut shell material), 22... caking material, 23... bio-molded coke

Claims

1. A mixing step of mixing the coconut shell material, which is coconut shell or coconut shell charcoal from which impurities have been removed, with a binder to obtain a mixture; a molding step of pressure-molding the mixture to obtain a molded body; a heating step of heating the molded body in a non-oxidizing atmosphere; A method for producing bio-molded coke comprising:

2. The method for producing biomolded coke according to claim 1, wherein a mixing ratio of the binder to the coconut shell material is 5% by mass or more and 30% by mass or less.

3. The method for producing biomolded coke according to claim 1 or 2, wherein the coconut shell material has an average particle size of 10 μm or more and 1,000 μm or less.

4. The method for producing bio-molded coke according to claim 1 or 2, wherein in the molding step, the mixture is pressure molded while being heated in the atmosphere to obtain the molded body.

5. The method for producing bio-molded coke according to claim 4 , wherein in the heating step, the molded body is heated at a temperature higher than a heating temperature in the molding step.

6. The method for producing biomolded coke according to claim 1 or 2, wherein the heating temperature in the heating step is 300°C or higher and 2,000°C or lower.

7. The method for producing biomolded coke according to claim 1 or 2, wherein the binder is coal tar pitch, asphalt pitch, wood tar, cement, bentonite, water glass, raw coal, caking coal, or a combination of two or more of these.

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