Method for manufacturing bio-molded charcoal

Abstract

The objective is to produce bio-molded charcoal that meets all the required functions of coal coke and can be used as an alternative fuel to coal coke. [Solution] Initial biochar, obtained by carbonizing biomass waste, is crushed to produce biopulverized charcoal by crushing the initial biochar so that more than 90% of the particle size is less than 300 μm. Next, the biopulverized charcoal and wood tar are kneaded at a temperature higher than room temperature so that the biopulverized charcoal contains at least 10-30% by weight of wood tar (preferably wood tar and black liquor) to produce kneaded biocharcoal. Next, the kneaded biocharcoal is pressurized and molded at a surface pressure of 50 MPa or more to produce pressurized biocharcoal. Subsequently, the pressurized biocharcoal is carbonized at a temperature of 600°C or higher to produce bio-molded charcoal in which the re-carbonized biopulverized charcoal contained in the pressurized biochar is bonded together with wood tar charcoal (preferably wood tar and black liquor charcoal).

Description

Technical Field

[0001] The present invention relates to a method for producing bioformed carbon as an alternative to coal coke.

Background Art

[0002] Aiming at the realization of a decarbonized society, as a carbon neutral effort to reduce the emissions of greenhouse gases such as carbon dioxide to zero, conversion activities to bioformed carbon are being carried out in the manufacturing industry such as machinery as an alternative fuel to coal coke used as a heat source in a cupola melting furnace for melting iron.

[0003] A cupola melting furnace is a vertically long shaft furnace. A cupola melting furnace is a furnace that melts steel scrap mainly composed of iron from a press factory that presses iron parts such as automobiles by the heat generated by burning coke obtained by carbonizing coal. In the cupola melting furnace, coal coke and steel scrap are charged in a state where they are alternately laminated, for example, and by blowing high-temperature hot air from a tuyere provided at the lower part of the furnace, the coal coke burns at a high temperature, melting the steel scrap, and at the same time, the molten metal is carburized by the carbon in the coke. The molten metal carburized in the cupola melting furnace is taken out from the cupola melting furnace and used for casting desired cast parts in subsequent processes, for example, parts around the feet such as knuckles and damper forks in automobiles.

[0004] The above coal coke is required to have three essential functions for use in a cupola melting furnace. The first function is to form a layer of only coke from the tuyere at the lower part of the furnace to a height of about 70 cm and support the large weights (several tons to dozens of tons) of deposits of steel scrap and coke in the furnace while maintaining the shape of the coke, that is, the function as a combustion bed called a coke bed or bed coke. The second function is a high-temperature combustion function in which coke burns at a high combustion temperature of 1800°C to 2000°C in order to obtain molten metal at a level of 1500°C from steel scrap. The third function is the function of carburizing the molten metal.

[0005] In recent years, the production of bio-molded charcoal from biomass has been considered as an alternative fuel to coal coke.

[0006] Patent Document 1 discloses a manufacturing method for producing molded char from biomass that allows for the firing of molded products without requiring separate fuel or combustion equipment.

[0007] In this method for producing molded char, biomass is thermally decomposed to produce a solid component, a gaseous component, and a gaseous liquid component. The solid component is pulverized, and the gaseous component and gaseous liquid component are cooled to separate them into a gaseous component and a liquid component containing wood vinegar and tar. The pulverized solid component is mixed with the liquid component of wood vinegar to form a kneaded mixture. This mixture is then molded to form a molded product, and the molded product is fired to obtain a molded char product.

[0008] In this molded char production method, the liquid component generated by gas-liquid separation of a gas-liquid mixture is separated by specific gravity into tar and wood vinegar. The separated tar is then burned, and the heat obtained from the combustion of the tar is used to calcine the molded product. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 5800235 [Overview of the project] [Problems that the invention aims to solve]

[0010] In the molded char production method described in Patent Document 1 above, wood vinegar is added as a binder to the crushed solid material, kneaded, and then molded. By firing this molded product using the heat of tar combustion, external fuel is not required.

[0011] However, Patent Document 1 mentioned above does not disclose a detailed method for producing bio-molded charcoal that has the three functions required for the coal coke used in the cupola melting furnace (i.e., function as a combustion bed, high-temperature combustion function, and charring function).

[0012] Furthermore, wood vinegar used as a binder is merely an acidic liquid from which tar has been removed, and inherently has low viscosity. Therefore, even if concentrated wood vinegar is mixed with the solid components of biomass char, sufficient bonding effect between the solid components cannot be obtained, and there is a high possibility of cracking during firing. In addition, even if the mixed molded material is fired, it is not possible to obtain molded char with high density and hardness. Consequently, it cannot perform the three functions required of coal coke as described above.

[0013] This invention has been made in view of the circumstances described above, and aims to provide a method for producing bio-molded charcoal that can be used as an alternative fuel to coal coke, as it satisfies all the functions required of coal coke. [Means for solving the problem]

[0014] To solve the above problems, the method for producing bio-molded charcoal according to claim 1 of the present invention comprises the steps of: preparing initial biocharcoal by carbonizing biomass waste; crushing the initial biocharcoal so that 90% or more of the particle size of the initial biocharcoal is less than 300 μm to produce bio-pulverized charcoal; and applying the bio-pulverized charcoal to te wood The bio-pulverized charcoal and wood tar are mixed at a temperature higher than room temperature so that they contain 15% tar by weight and 25% black liquor by weight. and the black liquid The present invention is characterized by comprising the steps of: kneading the materials to produce kneaded biochar; pressurizing the kneaded biochar at a surface pressure of 50 MPa or more to produce pressurized biochar; and carbonizing the pressurized biochar at a temperature of 600°C or higher to produce bio-molded charcoal in which the recarbonized bio-pulverized charcoal contained in the pressurized biochar is bonded together with the wood tar and the black liquor charcoal. Furthermore, the method for producing bio-molded charcoal according to claim 2 of the present invention includes the steps of: preparing initial biochar by carbonizing biomass waste; crushing the initial biochar so that 90% or more of the particle size of the initial biochar is less than 300 μm to produce bio-pulverized charcoal; and heating the bio-pulverized charcoal and wood tar at a temperature higher than room temperature so that the bio-pulverized charcoal contains 10-30% by weight of wood tar and also contains black liquor. and the black liquid The method is characterized by comprising the steps of: kneading to produce kneaded biochar; pressurizing the kneaded biochar at a surface pressure of 50 MPa or more to produce pressurized biochar; and carbonizing the pressurized biochar at a temperature in the range of 600 to 650°C to produce bio-molded charcoal in which the recarbonized bio-pulverized charcoal contained in the pressurized biochar is bonded together with the wood tar and the black liquor charcoal. Furthermore, the method for producing bio-molded charcoal according to claim 3 of the present invention comprises the steps of: preparing initial biochar by carbonizing biomass waste; crushing the initial biochar so that 90% or more of the particle size of the initial biochar is less than 300 μm to produce bio-pulverized charcoal; and heating the bio-pulverized charcoal and wood tar at a temperature higher than room temperature so that the bio-pulverized charcoal contains 15% by weight of wood tar and 25% by weight of black liquor. and the black liquid The method is characterized by comprising the steps of: kneading to produce kneaded biochar; pressurizing the kneaded biochar at a surface pressure of 50 MPa or more to produce pressurized biochar; and carbonizing the pressurized biochar at a temperature in the range of 600°C to 650°C to produce bio-molded charcoal in which the recarbonized bio-pulverized charcoal contained in the pressurized biochar is bonded together with the wood tar and the black liquor charcoal.

[0015] In the above manufacturing method, bio-pulverized charcoal is produced by carbonizing biomass waste and then finely grinding it so that more than 90% of the particle size is less than 300 μm. This makes it possible to eliminate the voids in the cellular structure of the biomass waste, which are factors that reduce the density of bio-molded charcoal.

[0016] and, In the method for producing bio-molded charcoal according to claims 1 and 3 of this application,For bio - micronized coal te wood mix tar with it at a weight ratio of 15 % It also contains 25% black liquor by weight. and knead the bio - micronized coal and the wood tar at a temperature higher than room temperature, so that it is possible to produce kneaded bio - coal in which the bio - micronized coal and the wood tar are evenly mixed. and black liquid Thus, because it contains 15% wood tar by weight and 25% black liquor by weight, it has the highest adhesive effect as a binder. Furthermore, in the method for producing bio-molded charcoal according to claim 2 of this application, it is possible to produce kneaded bio-charcoal in which bio-molded charcoal, wood tar, and black liquor are uniformly mixed by mixing bio-molded charcoal and wood tar in a weight ratio of 10 to 30% and further including black liquor, and kneading the bio-molded charcoal and wood tar at a temperature higher than room temperature.

[0017] After that, In the method for producing bio-molded charcoal according to claim 1 of this application, press - mold the kneaded bio - coal at a surface pressure of 50 MPa or more to produce pressed bio - coal, and carbonize the pressed bio - coal at a temperature of 600 °C or more. Thereby, carbides obtained by recarbonizing the bio - micronized coal contained in the pressed bio - coal are adhered to each other with the carbide of the wood tar and black liquor to produce bio - formed coal. Furthermore, in the method for producing bio-molded charcoal according to claims 2 and 3 of this application, pressurized bio-charcoal is produced by pressurizing and molding kneaded bio-charcoal at a surface pressure of 50 MPa or more, and the pressurized bio-charcoal is carbonized at a temperature in the range of 600°C to 650°C. This produces bio-molded charcoal in which the carbonized bio-pulverized charcoal contained in the pressurized bio-charcoal is recarbonized and bonded together with carbonized wood tar and black liquor.

[0018] In the above - mentioned In the method for producing bio-molded charcoal according to claims 1 and 3 of this application, production of kneaded bio - coal, Because it contains 15% wood tar by weight and 25% black liquor by weight, it has the highest adhesive effect as a binder. This kneaded biochar is then pressurized. carbides obtained by recarbonizing the bio - micronized coal contained in the pressed bio - coal are composed of bio - micronized coal with voids eliminated, so their density is high. Therefore, by carbonizing the pressed bio - coal at a temperature of 600 °C or more and firmly adhering these recarbonized carbides to each other with The weight percentage that provides the best adhesive effect the carbide of the wood tar and black liquor it becomes possible to manufacture bio - formed coal having a high density and a high hardness. Furthermore, in the method for producing bio-molded charcoal according to claims 2 and 3 of this application, by carbonizing the pressurized bio-charcoal at a temperature in the range of 600 to 650°C, the difference in shrinkage due to the temperature difference inside and outside the pressurized bio-charcoal before recarbonization and the bio-molded charcoal after recarbonization can be reduced. Therefore, cracking of the pressurized bio-charcoal during recarbonization and the bio-molded charcoal after recarbonization is least likely to occur during both recarbonization and combustion in the furnace.

[0019] By the method for producing bio-molded charcoal according to claims 1 to 3 of this application described above The produced bio - formed coal can exhibit three functions required for coal coke, namely, the function as a combustion bed, the combustion function with a high combustion temperature of 1800 °C to 2000 °C, and the function of adding carbon to molten metal. Therefore, by the above - mentioned manufacturing method, it is possible to manufacture bio - formed coal that satisfies all the functions required for coal coke and can be used as an alternative fuel for coal coke.

[0020] In the above - mentioned The present application relating to claims 1 to 3 method for manufacturing bio - formed coal So, The mixed biochar is produced by adding black liquor to the aforementioned biopulverized charcoal and wood tar and kneading them together. 。

[0021] Black liquor is a liquid containing thermosetting phenolic resins such as lignin, which are mainly produced as a by-product during pulp manufacturing. It is easier to obtain than wood tar, and carbonization of black liquor provides a strong adhesive effect similar to wood tar. Therefore, by adding and kneading black liquor to produce kneaded biochar and then manufacturing bio-molded charcoal, the amount of wood tar used can be reduced, and the manufacturing cost of bio-molded charcoal can be lowered.

[0022] In the above-described method for producing bio-molded charcoal, it is preferable to crush the initial bio-charcoal so that 90% or more of the particle size of the initial bio-charcoal is 106 μm or less in order to produce the bio-pulverized charcoal.

[0023] This process generates finer bio-pulverized coal more uniformly, making it possible to more reliably eliminate voids in the cellular structure of biomass waste, which are a factor that reduces the density of bio-molded coal. As a result, it becomes possible to more reliably produce bio-molded coal with high density and high hardness.

[0024] In the above-described method for producing bio-molded charcoal, it is preferable to preheat the bio-pulverized charcoal and at least the wood tar before mixing them, or to mix the bio-pulverized charcoal and at least the wood tar while heating them.

[0025] Because wood tar has high viscosity, mixing preheated bio-pulverized charcoal with wood tar, or mixing while heating, allows for even mixing of the pressurized bio-charcoal and wood tar, thereby enabling the wood tar to exhibit a greater adhesive effect during carbonization.

[0026] In the above-described method for producing bio-molded charcoal, it is preferable that the temperature at which the bio-pulverized charcoal and at least the wood tar are heated is 55 to 65°C.

[0027] By heating and kneading within the above range, the bio-pulverized charcoal and wood tar can be mixed more evenly, and the adhesive effect of the wood tar during carbonization can be further enhanced.

[0028] In the above-described method for producing bio-molded charcoal, it is preferable to pressurize the kneaded bio-charcoal with a surface pressure of 100 MPa or more to mold the pressurized bio-charcoal.

[0029] In the above manufacturing method, pressurizing the kneaded biochar with a surface pressure of 100 MPa or more to mold the pressurized biochar allows air to escape from the pressurized biochar, increasing its density. This makes it less likely for the pressurized biochar to crack or break when carbonizing it to produce bio-molded charcoal. Furthermore, it also makes it less likely for the manufactured bio-molded charcoal to crack or break when burned at high temperatures of 1800-2000°C.

[0030] In the above-described method for producing bio-molded charcoal, it is preferable to produce bio-molded charcoal for use in a cupola melting furnace.

[0031] The above manufacturing method produces bio-molded charcoal used in cupola melting furnaces. Therefore, it can be used as an alternative fuel to coal coke in cupola melting furnaces, thereby reducing coal coke consumption. Consequently, it can significantly contribute to carbon neutrality. [Effects of the Invention]

[0032] As described above, the method for producing bio-molded charcoal of the present invention makes it possible to produce bio-molded charcoal that satisfies all the functions required of coal coke and can be used as an alternative fuel to coal coke. [Brief explanation of the drawing]

[0033] [Figure 1] This flowchart shows the process flow of a method for producing bio-molded charcoal according to an embodiment of the present invention, and also schematically shows the products of the main steps. [Figure 2]This is a schematic cross-sectional diagram illustrating the structure of a cupola melting furnace that uses bio-molten charcoal as an alternative fuel to coal coke. [Figure 3] This graph shows the time-dependent changes in the temperature of wood tar and the time-dependent changes in the weight loss rate of wood tar. [Figure 4] This graph shows the time-dependent changes in the temperature of the black liquor and the time-dependent changes in the weight loss rate of the black liquor. [Figure 5] This graph shows the relationship between the heating temperature and the coefficient of linear expansion of pressurized biochar, which is biochar before recarbonization. [Figure 6] This graph shows the relationship between the heating temperature and the coefficient of linear expansion of bio-molded charcoal, which is biochar after recarbonization. [Modes for carrying out the invention]

[0034] Hereinafter, a method for producing bio-molded charcoal according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0035] In the method for producing bio-molded charcoal according to an embodiment of the present invention, bio-molded charcoal is produced for use in a cupola melting furnace as an alternative fuel to coal coke. Here, the cupola melting furnace has the following structure.

[0036] (Explanation of a cupola melting furnace) As an example of a cupola melting furnace, the cupola melting furnace 30 shown in Figure 2 is a vertical shaft furnace that uses bio-molded charcoal as fuel to melt iron-based materials such as the above-mentioned steel scrap and produce molten metal for casting. Specifically, the cupola melting furnace 30 has a vertical cylindrical furnace body 31, a wind box 32 into which hot air is introduced, a guide pipe 34 that connects the wind box 32 and the tuyere 33 at the bottom of the furnace body 31 and sends hot air into the furnace body 31 from the tuyere 33, and a gas inlet 36 located between the upper end and the middle of the furnace body 31 that recovers the high-temperature exhaust gas that comes out of the furnace body 31. The hot air introduced into the wind box 32 is generated using the high-temperature exhaust gas that comes out of the gas inlet 36.

[0037] In the cupola melting furnace 30 configured as described above, in order to melt steel scrap mainly composed of iron, bio-molded charcoal and steel scrap are charged from the charging port 37 at the upper end of the furnace body 31, for example, in an alternating stacked state. Note that in Figure 1, a mixture 35 of bio-molded charcoal and steel scrap is shown for simplification. Inside the furnace body 31, fine bio-molten charcoal is blown in along with high-temperature hot air from tuyeres 33 located at the bottom of the furnace body 31. As a result, the steel scrap is melted by the combustion of the bio-molded charcoal and bio-molten charcoal at high temperatures, and at the same time, the molten metal is carburized by the carbon in the bio-molded charcoal and bio-molten charcoal, making it possible to produce carburized molten metal for casting.

[0038] (Method for manufacturing bio-molded charcoal) As described above, in order to produce bio-molded charcoal used in the cupola melting furnace 30 as an alternative fuel to coal coke, the process is broadly divided into raw material carbonization, molding, and binder carbonization, as shown in Figure 1. The specific method for producing bio-molded charcoal is as follows.

[0039] <Explanation of raw material carbonization> To carry out raw material carbonization, the first step is to accept (i.e., procure or prepare) the biowaste that will be used as raw material for bio-molded charcoal. Biowaste is organic resources of biological origin that are discharged as industrial waste or household waste from agriculture, forestry, manufacturing, etc., and is also called waste biomass. Suitable materials from biowaste to be used as raw material for bio-molded charcoal include, for example, bark, waste pulp, pomace from citrus fruits such as lemons and oranges, chestnut peels, waste bamboo from oyster rafts, wood chips, coconut shells, tea leaves, coffee grounds, wooden or paper packaging materials, discarded paper materials such as paper cups, fruit tree pruning branches, and sawdust.

[0040] Next, the collected biowaste is roughly dried to remove moisture and then crushed. The crushed biowaste is then carbonized to produce initial biochar. This completes the raw material carbonization process.

[0041] In the manufacturing method of the above embodiment, biowaste is carbonized to produce initial biochar. However, in the present invention, it is sufficient to prepare initial biochar by carbonizing biowaste, and it is not necessary to prepare initial biochar by generating it each time bio-molded charcoal is manufactured. Therefore, initial biochar by carbonizing biowaste may be prepared in advance by purchasing it from another company.

[0042] <Explanation of molding process> Next, in order to mold the biochar (pressurized biochar) into a predetermined shape (for example, a cylindrical shape with a diameter of 5 to 15 cm and a height of 5 to 15 cm) before recarbonization, the initial biochar is first finely pulverized. Specifically, in order to prevent the density of the finished bio-molded charcoal from being reduced by the voids in the cellular structure of the bio-waste, the initial biochar is pulverized so that more than 90% of the particle size is less than 300 μm (preferably 106 μm or less) to produce bio-pulverized charcoal.

[0043] In particular, it is preferable to crush the initial biochar so that more than 90% of the initial biochar has a particle size of 106 μm or less to produce biopulverized biochar, as this allows for the more uniform production of fine biopulverized biochar.

[0044] Next, a binder is added to the biopulverized charcoal, and the biopulverized charcoal and binder are kneaded together. Specifically, at least wood tar (preferably wood tar and black liquor) is added as the binder. In this embodiment, wood tar and black liquor are added as the binder so that at least 10-30% by weight of wood tar is added to the biopulverized charcoal, and the biopulverized charcoal, wood tar, and black liquor are kneaded together at a temperature higher than room temperature (e.g., 60°C or higher) to produce kneaded biocharcoal. In this kneading process, as shown in Figure 1, it becomes possible to evenly cover the entire outer surface of the biopulverized charcoal 11 with the binder 12 consisting of wood tar and black liquor.

[0045] Next, we will explain in detail the wood tar and black liquor used as binders.

[0046] Wood tar is a liquid separated from crude wood vinegar, which is obtained by condensing the smoke and gases produced during the carbonization of biomass raw materials, based on density differences. Wood tar contains about half water, and its solid content is 30-50%.

[0047] Wood tar contains approximately 70% carbon, and for example, carbonizing cedar wood at 400°C yields about 60% of the carbon content of charcoal. Therefore, carbonizing cedar waste wood provides cost-free wood tar and also improves the yield of raw materials. Thus, wood tar can be considered a low-cost, sustainably available, and highly adhesive binder.

[0048] Wood tar contains a wide variety of compounds as its main components, including phenols such as phenol, cresol, and guaiacol; esters such as methyl acetate; aldehydes such as varelualdehyde and propionaldehyde; and other compounds such as alcohols, ketones, bases, furans, and lactones.

[0049] Although wood tar is available free of charge or at low cost as a by-product of charcoal production, it only accounts for about 15% of the weight of the raw wood. Therefore, supplementing it with black liquor is effective in ensuring a more stable supply of the required amount of binder.

[0050] Black liquor is a liquid containing thermosetting phenolic resin. It is waste pulp liquid from paper mills and other sources. In paper mills, lignin is dissolved in sulfuric acid to extract cellulose and hemicellulose, which are raw materials for paper, from wood. The waste liquid from this process is black liquor. The lignin dissolved in black liquor is a thermosetting phenolic resin that plays a role in bonding cellulose cells together and forming the tissue structure of wood. When carbonized, the carbon atoms of the benzene ring remain, resulting in a strong adhesive effect.

[0051] By using a binder consisting of the above-mentioned combination of wood tar and black liquor, it becomes possible to produce bio-molded charcoal with cold static strength comparable to or greater than that of coal coke.

[0052] The binder mixture is preferably composed of 25% black liquor and 15% wood tar by weight relative to bio-pulverized charcoal, as this provides the best adhesive effect.

[0053] Simply mixing bio-pulverized charcoal with a binder of wood tar and black liquor does not result in sufficient adhesive strength for the binder. Therefore, it is important to knead the bio-pulverized charcoal with the binder of wood tar and black liquor, as in the manufacturing method of this embodiment. Through kneading, the bio-pulverized charcoal and the binder not only mix together, but the binder also disperses and coats the outer surface of the bio-pulverized charcoal.

[0054] Furthermore, because wood tar has high viscosity, it is preferable to heat it to about 60°C, which is higher than room temperature, and knead it using a high-speed fluid mixer (for example, a Henschel mixer).

[0055] Furthermore, regarding heating and mixing, it is preferable to preheat the bio-pulverized charcoal and at least wood tar (preferably wood tar and black liquor) before mixing, or to mix while heating the bio-pulverized charcoal and at least wood tar.

[0056] Regarding the heating temperature conditions, it is preferable that the temperature at which the biopulverized charcoal and at least wood tar (preferably wood tar and black liquor) are heated is 55 to 65°C.

[0057] Next, the kneaded biochar is pressurized and molded under a surface pressure of 50 MPa or more (preferably 100 MPa or more) to form a predetermined shape (for example, a cylindrical shape with a diameter of 5 to 15 cm and a height of 5 to 15 cm) to produce pressurized biochar. In this pressurized molding process, as shown in Figure 1, the bio-pulverized charcoal 11 particles are densely pressed together inside a molding die (not shown) with a binder 12 in between, and are molded into pressurized biochar of a predetermined shape (for example, a cylindrical shape).

[0058] In particular, pressurizing the mixed biochar with a surface pressure of 100 MPa or more is preferable because it removes air from the pressurized biochar and increases its density. More preferably, the surface pressure is around 150 to 250 MPa, and the most preferable surface pressure is around 200 MPa. By pressurizing and molding with a surface pressure of around 200 MPa, excess air is almost completely removed from the bio-molded charcoal, so performance similar to coal coke can be obtained more reliably.

[0059] <Explanation of binder carbonization> Next, the pressurized biochar obtained by pressurized molding is carbonized at a temperature of 600°C or higher (preferably 800°C or higher) to produce bio-molded charcoal in which the recarbonized bio-pulverized charcoal contained in the pressurized biochar is firmly bonded together with wood tar charcoal. Here, as shown in Figure 1, the recarbonization process produces bio-molded charcoal 23 in which the recarbonized bio-pulverized charcoal 21 is firmly bonded together with wood tar and black liquor charcoal binder 22.

[0060] As shown in the graph in Figure 3, when wood tar is heated, the weight loss rate W1 (weight %) of the wood tar decreases in stages as the temperature T1 (°C) of the wood tar rises over time. Looking at the graph in Figure 3, when the temperature T1 of the wood tar reaches 600°C or higher, the weight loss rate W1 of the wood tar becomes constant. This indicates that the water in the wood tar has completely evaporated and the volatilization of the wood tar has completely finished, and the entire wood tar has become carbonized, so the weight loss of the wood tar has stopped. Therefore, it can be seen that when the temperature T1 of the wood tar reaches 600°C or higher, the carbonized wood tar enables strong adhesion between the biochars.

[0061] Furthermore, as shown in the graph in Figure 4, when the black liquor is heated, the weight loss rate W2 (weight %) of the black liquor decreases in stages as the temperature T2 (°C) of the black liquor rises in stages over time. Looking at the graph in Figure 4, when the temperature T2 of the black liquor reaches 800°C or higher, the weight loss rate W2 of the black liquor becomes constant. This indicates that the water in the black liquor has completely evaporated and the evaporation of the black liquor has completely finished, and the entire black liquor has turned into carbon, so the weight loss of the black liquor has stopped. Therefore, it can be seen that when the temperature T2 of the black liquor reaches 800°C or higher, the carbon of the black liquor enables strong adhesion between biochars.

[0062] Therefore, the results from the graphs in Figures 3 and 4 show that in the re-carbonization process shown in Figure 1, a strong adhesive effect can be obtained from the carbonized wood tar at heating temperatures of 600°C or higher. Furthermore, it can be seen that an even stronger adhesive effect can be obtained from the carbonized wood tar and black liquor at heating temperatures of 800°C or higher.

[0063] Furthermore, as shown in the graphs in Figures 3-4, if the temperature T1 of the wood tar and the temperature T2 of the black liquor are maintained at 900°C for a long period of time exceeding 180 minutes, the carbonized material in the wood tar and black liquor will turn to ash and disappear. Therefore, heating must be completed in less than 180 minutes.

[0064] Next, we will examine the change in the linear expansion coefficient of pressurized biochar during the recarbonization process, referring to the graphs in Figures 5 and 6. Figure 5 is a graph showing the relationship between the heating temperature and the linear expansion coefficient of pressurized biochar, which is biochar before recarbonization. Figure 6 is a graph showing the relationship between the heating temperature and the linear expansion coefficient of bio-molded charcoal, which is biochar after recarbonization.

[0065] As can be seen in the graph in Figure 5, the linear expansion coefficient of pressurized biochar, which is biochar before recarbonization, decreases sharply when the heating temperature exceeds 600°C. This means that when the heating temperature exceeds 600°C, the degree of contraction of the binder (wood tar and black liquor) contained in the pressurized biochar increases, and the difference in contraction between the inside and outside of the pressurized biochar becomes large during the recarbonization process.

[0066] On the other hand, the linear expansion coefficient of bio-molded charcoal, which is biochar after recarbonization, begins to decrease when the heating temperature exceeds 600°C and decreases sharply above 700°C. This means that when the heating temperature exceeds 600°C, the carbonized binders (wood tar and black liquor carbonized materials) contained in the bio-molded charcoal begin to contract, and the degree of contraction increases with rising temperature. This means that when the bio-molded charcoal is burned in a cupola melting furnace, the difference in contraction between the inside and outside of the bio-molded charcoal becomes large.

[0067] As can be seen from the graphs in Figures 5 and 6 above, by setting the recarbonization temperature for heating the pressurized biochar in the recarbonization process to around 600°C (for example, around 600-650°C), which is just before the temperature range in which the binder rapidly contracts, the difference in contraction due to the temperature difference inside and outside the pressurized biochar before recarbonization and the bio-molded charcoal after recarbonization can be reduced. Therefore, cracking of the pressurized biochar during recarbonization and the bio-molded charcoal after recarbonization is least likely to occur during both recarbonization and combustion in the cupola furnace.

[0068] (Features of this embodiment) (1) The method for producing bio-molded charcoal according to this embodiment is characterized by the steps of: preparing initial biochar by carbonizing biomass waste to produce initial biochar; crushing the initial biochar so that 90% or more of the particle size of the initial biochar is less than 300 μm (preferably 106 μm or less) to produce bio-pulverized charcoal; kneading the bio-pulverized charcoal and the wood tar at a temperature higher than room temperature so that the bio-pulverized charcoal contains at least 10 to 30% by weight of wood tar (preferably wood tar and black liquor) to produce kneaded biocharcoal; pressurizing the kneaded biocharcoal at a surface pressure of 50 MPa or more to produce pressurized biocharcoal; and carbonizing the pressurized biocharcoal at a temperature of 600°C or higher to produce bio-molded charcoal in which the re-carbonized bio-pulverized charcoal contained in the pressurized biocharcoal is bonded together with wood tar charcoal.

[0069] In the above manufacturing method, bio-pulverized charcoal is produced by carbonizing the biomass waste and then finely grinding it so that 90% or more of the particle size is less than 300 μm (preferably 106 μm or less). This makes it possible to eliminate the voids in the cellular structure of the biomass waste, which are factors that reduce the density of bio-molded charcoal.

[0070] Furthermore, by mixing biopulverized charcoal with wood tar in a weight proportion of at least 10-30%, and kneading the biopulverized charcoal and wood tar at a temperature higher than room temperature (preferably 55-65°C, more preferably around 60°C), it is possible to produce kneaded biocharcoal in which the biopulverized charcoal and wood tar are evenly mixed.

[0071] Subsequently, the mixed biochar is pressurized and molded under a surface pressure of 50 MPa or more to produce pressurized biochar, and the pressurized biochar is carbonized at a temperature of 600°C or higher. This process generates bio-molded charcoal in which the bio-pulverized charcoal contained in the pressurized biochar is re-carbonized and bonded together with wood tar charcoal.

[0072] In the above manufacturing method, the charred material obtained by recarbonizing the bio-pulverized charcoal contained in the pressurized biochar is composed of bio-pulverized charcoal with no voids, resulting in a high density. Therefore, by carbonizing the pressurized biochar at a temperature of 600°C or higher and firmly bonding these recarbonized charred materials together with wood tar char, it becomes possible to produce bio-molded charcoal with high density and high hardness.

[0073] The bio-molded charcoal produced in this way can perform the three functions required of coal coke: namely, its function as a combustion bed, its combustion function that achieves a high combustion temperature of 1800°C to 2000°C, and its function of carburizing molten metal. Therefore, it can satisfy all the functions required of coal coke and can be used as an alternative fuel to coal coke.

[0074] By producing bio-molded charcoal from the bio-waste described above, it is possible to contribute to carbon neutrality by eliminating carbon dioxide emissions during coal coke production. Furthermore, when bio-molded charcoal is used as an alternative fuel to coal coke in a cupola melting furnace, it does not contain sulfur, unlike coal coke, thus eliminating the need for a desulfurization process for the molten metal produced in the cupola melting furnace.

[0075] (2) In the method for producing bio-molded charcoal of this embodiment, black liquor is added to bio-pulverized charcoal and wood tar and kneaded to produce kneaded bio-charcoal.

[0076] Black liquor is a liquid containing thermosetting phenolic resins such as lignin, which are mainly produced as a by-product during pulp manufacturing. It is easier to obtain than wood tar, and carbonization of black liquor provides a strong adhesive effect similar to wood tar. Therefore, by adding and kneading black liquor to produce kneaded biochar and then manufacturing bio-molded charcoal, the amount of wood tar used can be reduced, and the manufacturing cost of bio-molded charcoal can be lowered.

[0077] (3) In the method for producing bio-molded charcoal of this embodiment, it is preferable to crush the initial biocharcoal so that 90% or more of the particle size of the initial biocharcoal is 106 μm or less in order to produce bio-pulverized charcoal.

[0078] This process generates finer bio-pulverized coal more uniformly, making it possible to more reliably eliminate voids in the cellular structure of biomass waste, which are a factor that reduces the density of bio-molded coal. As a result, it becomes possible to more reliably produce bio-molded coal with high density and high hardness.

[0079] (4) In the method for producing bio-molded charcoal according to this embodiment, it is preferable to preheat the bio-pulverized charcoal and at least the wood tar before mixing them, or to mix the bio-pulverized charcoal and at least the wood tar while heating them.

[0080] Because wood tar has high viscosity, mixing preheated bio-pulverized charcoal with wood tar, or mixing while heating, allows for even mixing of the pressurized bio-charcoal and wood tar, thereby enabling the wood tar to exhibit a greater adhesive effect during carbonization.

[0081] (5) In the bio-molded charcoal manufacturing method of this embodiment, the temperature at which the bio-pulverized charcoal and at least wood tar are heated is preferably 55 to 65°C. By heating and kneading within this range, the bio-pulverized charcoal and wood tar are mixed more evenly, and the adhesive effect of the wood tar during carbonization can be further enhanced.

[0082] (6) In the bio-molded charcoal manufacturing method of this embodiment, it is preferable to pressurize the kneaded bio-charcoal with a surface pressure of 100 MPa or more to form pressurized bio-charcoal. In the above manufacturing method, by pressurizing the kneaded bio-charcoal with a surface pressure of 100 MPa or more to form pressurized bio-charcoal, air is released from the pressurized bio-charcoal and its density increases, so when the pressurized bio-charcoal is carbonized to produce bio-molded charcoal, abnormalities such as cracking of the pressurized bio-charcoal are less likely to occur. Furthermore, when the manufactured bio-molded charcoal is used by burning it at a high temperature of 1800 to 2000°C, abnormalities such as cracking are less likely to occur.

[0083] (7) The bio-molded charcoal manufacturing method of this embodiment produces bio-molded charcoal for use in a cupola melting furnace. Since the above manufacturing method produces bio-molded charcoal for use in a cupola melting furnace, it can be used in the cupola melting furnace as an alternative fuel to the coal coke used, thereby reducing the amount of coal coke consumed. Therefore, it can make a significant contribution to carbon neutrality.

[0084] (modified version) The above embodiment of the method for producing bio-molded charcoal produces bio-molded charcoal used in a cupola melting furnace, but the present invention is not limited to bio-molded charcoal used only in a cupola melting furnace. Therefore, the present invention may produce bio-molded charcoal for use in other locations as long as it is used as a substitute for coal coke. [Explanation of Symbols]

[0085] 11. Biopulverized coal 12 Binders 13 Pressurized Biochar 21. Carbonized biopulverized coal 22. Binder carbides 23. Bio-molded charcoal 30 Cupola melting furnace

Claims

1. The process of preparing initial biochar by carbonizing biomass waste, A step of producing biopulverized biochar by crushing the initial biochar so that 90% or more of the particle size of the initial biochar is less than 300 μm, A step of producing kneaded biochar by kneading the bio-pulverized charcoal, wood tar and black liquor at a temperature higher than room temperature so that the bio-pulverized charcoal contains 15% by weight of wood tar and 25% by weight of black liquor, The process of pressurizing the aforementioned kneaded biochar by pressurizing and molding it with a surface pressure of 50 MPa or more to produce pressurized biochar, The process includes carbonizing the pressurized biochar at a temperature of 600°C or higher to produce bio-molded charcoal in which the re-carbonized bio-pulverized charcoal contained in the pressurized biochar is bonded together with the wood tar and the black liquor charcoal. A method for producing bio-molded charcoal, characterized by the following features.

2. The process of preparing initial biochar by carbonizing biomass waste, A step of producing biopulverized biochar by crushing the initial biochar so that 90% or more of the particle size of the initial biochar is less than 300 μm, A step of producing kneaded biochar by kneading the bio-pulverized charcoal, wood tar and black liquor at a temperature higher than room temperature so that the bio-pulverized charcoal contains 10 to 30% by weight of wood tar and also contains black liquor, The process of pressurizing the aforementioned kneaded biochar by pressurizing and molding it with a surface pressure of 50 MPa or more to produce pressurized biochar, The process includes a step of carbonizing the pressurized biochar at a temperature in the range of 600 to 650°C to produce bio-molded charcoal in which the re-carbonized bio-pulverized charcoal contained in the pressurized biochar is bonded together with the wood tar and the black liquor charcoal. A method for producing bio-molded charcoal, characterized by the following features.

3. The process of preparing initial biochar by carbonizing biomass waste, A step of producing biopulverized biochar by crushing the initial biochar so that 90% or more of the particle size of the initial biochar is less than 300 μm, A step of producing kneaded biochar by kneading the bio-pulverized charcoal, wood tar and black liquor at a temperature higher than room temperature so that the bio-pulverized charcoal contains 15% by weight of wood tar and 25% by weight of black liquor, The process of pressurizing the aforementioned kneaded biochar by pressurizing and molding it with a surface pressure of 50 MPa or more to produce pressurized biochar, The process includes a step of carbonizing the pressurized biochar at a temperature in the range of 600°C to 650°C to produce bio-molded charcoal in which the re-carbonized bio-pulverized charcoal contained in the pressurized biochar is bonded together with the wood tar and the black liquor charcoal. A method for producing bio-molded charcoal, characterized by the following features.

4. In the method for producing bio-molded charcoal according to any one of claims 1 to 3, The initial biochar is crushed so that 90% or more of the initial biochar has a particle size of 106 μm or less to produce the bio-pulverized biochar. A method for producing bio-molded charcoal, characterized by the following features.

5. In the method for producing bio-molded charcoal according to any one of claims 1 to 3, The bio-pulverized charcoal and at least the wood tar are preheated before mixing, or the bio-pulverized charcoal and at least the wood tar are mixed while being heated. A method for producing bio-molded charcoal, characterized by the following features.

6. In the method for producing bio-molded charcoal according to claim 5, The temperature at which the bio-pulverized charcoal and at least the wood tar are heated is characterized by being 55 to 65°C. A method for producing bio-molded charcoal, characterized by the following features.

7. In the method for producing bio-molded charcoal according to any one of claims 1 to 3, The kneaded biochar is pressed with a surface pressure of 100 MPa or more to form the pressurized biochar. A method for producing bio-molded charcoal, characterized by the following features.

8. In the method for producing bio-molded charcoal according to any one of claims 1 to 3, To manufacture bio-molded charcoal used in cupola melting furnaces, A method for producing bio-molded charcoal, characterized by the following features.

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