solid fuels

Abstract

To provide a solid fuel that has sufficient strength in a high-temperature environment. [Solution] A solid fuel is provided which contains biomass char and has a hot strength of 1000N or more, measured after heating in air at 1000°C for 30 minutes and then cooling, and which contains an inorganic binder with a CaO content of 50% by mass or more in a dry state.

Description

Technical Field

[0001] The present disclosure relates to solid fuel and a method for producing the same.

Background Art

[0002] As a means for reducing CO2 for measures against global warming, technological development using biomass instead of existing fossil fuels has been promoted. In Patent Document 1, it has been proposed to use a carbon-containing molded product obtained by adding a binder to biomass carbide, molding it, and carbonizing it, instead of coke used in waste melting treatment facilities.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, when using a carbon-containing molded product as fuel, an organic binder is considered preferable. However, organic binders are generally expensive and difficult to maintain strength in a high-temperature environment. Therefore, the present disclosure provides a solid fuel having sufficient strength in a high-temperature environment and a method for producing the same.

Means for Solving the Problems

[0005] One aspect of the present disclosure provides a solid fuel including a biomass carbide having a fixed carbon of 85% by mass or more on an ash-free and moisture-free basis and an inorganic binder having a CaO content of 50% by mass or more in a dry state. Since this solid fuel contains a biomass carbide having a fixed carbon of 85% by mass or more and an inorganic binder, it has sufficient strength in a high-temperature environment.

[0006] One aspect of this disclosure provides a method for producing solid fuel, comprising the step of kneading and molding a molding raw material containing biomass char with fixed carbon content of 85% by mass or more on an anhydrous, ash-free basis, an inorganic binder with a CaO content of 50% by mass or more in a dry state, and water. In this production method, because biomass char with fixed carbon content of 85% by mass or more and an inorganic binder are used, the fuel has sufficient strength in a high-temperature environment. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a solid fuel having sufficient strength in a high-temperature environment and a method for manufacturing the same. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows an example of a gasification and melting furnace and a waste melting treatment facility equipped with it. [Figure 2] This is a diagram illustrating the methods for measuring hot strength and cold strength. [Modes for carrying out the invention]

[0009] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings, where applicable. The following embodiments are illustrative for the purpose of illustrating the present disclosure and are not intended to limit the present disclosure to the following.

[0010] One embodiment of the solid fuel comprises a biomass char with a fixed carbon content of 88% by mass or more on an anhydrous, ash-free basis, and an inorganic binder with a CaO content of 50% by mass or more in a dry state.

[0011] In this specification, biomass refers to biological resources other than fossil fuels. Examples of biomass include thinned wood, pruned branches, waste wood, bark chips, other wood, bamboo, grass, coconut shells, palm oil residue, vegetables, fruits, food waste, sludge, and other waste materials. The biomass may be woody biomass such as thinned wood, pruned branches, waste wood, bark chips, and other wood. Biomass char can be obtained by dry distillation of such biomass.

[0012] The fixed carbon content of biomass char may be 85% or more by mass, 88% or more by mass, or 90% or more by mass on an anhydrous, ashless basis. Biomass char with a high fixed carbon content has low volatile content, meaning that fewer components volatilize even in high-temperature environments. Therefore, it can maintain sufficient strength even in high-temperature environments. The fixed carbon content on an anhydrous, ashless basis can be determined by converting the value of the fixed carbon content on an anhydrous basis, measured in accordance with "8. Method for calculating fixed carbon mass fraction (%)" of JIS M 8812:2006 "Coal and coke - Industrial analysis methods," to an anhydrous, ashless basis value.

[0013] The particle size of the biomass char may be 10 mm or less, 2 mm or less, 0.5 to 2 mm, or 0.8 to 1.5 mm. If the particle size is too large, the adhesion between the biomass char particles may decrease, leading to a decrease in strength. If the particle size is too small, the contact area between the biomass char particles may increase too much, leading to a decrease in strength. The particle size of the biomass char can be measured using a sieve. When sieved using a sieve with a mesh size of 2 mm, the particle size below the sieve is 2 mm or less.

[0014] The biomass char content in solid fuels is 50% by mass or more, and may be 60% by mass or 65% by mass or more. By increasing the biomass char content, the calorific value of the solid fuel can be sufficiently increased. The biomass char content in solid fuels may be 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less. Such solid fuels can have even higher strength in high-temperature environments.

[0015] Inorganic binders are inorganic substances that have the function of binding together particles of biomass char. In an inorganic binder, the CaO content is 50% by mass or more in a dry state. In an inorganic binder, the CaO content may be 55% by mass or more, or 60% by mass or more in a dry state. Such inorganic binders can reduce the melting point of slag when used as solid fuel in a gasification melting furnace or cupola furnace. In these facilities, limestone is sometimes used as an auxiliary material, but some or all of the limestone can be replaced by the CaO in the inorganic binder.

[0016] Figure 1 shows a waste melting treatment facility 100 equipped with a coke bed type melting furnace 40, which is an example of a gasification melting furnace. The solid fuel in this embodiment can replace the coke in such a melting furnace 40. The waste melting treatment facility 100 in Figure 1 comprises a melting furnace 40 and a charging device 50 provided on the upper part of the melting furnace 40. The melting furnace 40 has a shaft portion 42, a bell-shaped portion 44 provided at the lower end of the shaft portion 42, and a furnace bottom portion 46 provided below the bell-shaped portion 44. From the shaft portion 42 to the furnace bottom portion 46, upper tuyeres 45 for the pyrolysis zone and lower tuyeres 47 for the combustion melting zone are provided in order from top to bottom. The upper tuyeres 45 and lower tuyeres 47 may each be provided in multiple stages.

[0017] Waste, solid fuel, and auxiliary materials are charged into the melting furnace 40 by the charging device 50. Examples of waste include general waste, industrial waste, processed materials such as incinerated ash obtained by drying, incineration, crushing, etc., and landfill waste containing soil and sand that has been excavated after being landfilled. Auxiliary materials may include at least one selected from limestone, iron ore, magnesia, periclase, cudolite, and jamonite. By using such auxiliary materials, the waste 48 can be sufficiently melted inside the melting furnace 40. In addition to the solid fuel of this embodiment, coal, coke, or molten coal may also be used.

[0018] Waste, solid fuel, and auxiliary materials are charged from the charging device 50 into the melting furnace 40. Oxygen or oxygen-enriched air is supplied from the lower tuyere 47, and air is supplied from the upper tuyere 45 as combustion-supporting gas. The solid fuel charged into the melting furnace 40 is burned by the oxygen or oxygen-enriched air supplied from the lower tuyere 47 and functions as a heat source. The waste 48 containing the auxiliary materials charged into the melting furnace 40 is heated to, for example, 1600 °C or higher by the combustion of the solid fuel and becomes the pyrolysis residue 43. The pyrolysis residue 43 is mainly burned by the air supplied from the upper tuyere 45.

[0019] The pyrolysis gas generated in the melting furnace 40 rises through the shaft portion 42 and is introduced from the exhaust gas pipe 52 connected to the lower part of the charging device 50 into the combustion chamber. The combustion exhaust gas is burned as a combustible gas and then the waste heat is recovered in a boiler. Thereafter, the exhaust gas is cooled in a desuperheating tower and then discharged from the chimney after passing through a dust collector and a catalytic reaction tower.

[0020] A temperature gradient is generated inside the melting furnace 40 by the combustion of solid fuel and the like. Specifically, the melting furnace 40 has a drying / preheating zone 40a, a pyrolysis zone 40b, and a combustion / melting zone 40c from top to bottom. The auxiliary materials introduced from the charging device 50 into the melting furnace 40 reach the drying / preheating zone 40a, the pyrolysis zone 40b, and the combustion / melting zone 40c in this order together with the waste and the solid fuel. CaO and the like contained in the inorganic binder of the solid fuel reach the combustion / melting zone 40c.

[0021] The combustible components in the waste 48 and the biomass carbide contained in the solid fuel are gasified and rise in the melting furnace 40 and are introduced into the combustion chamber via the exhaust gas pipe 52. On the other hand, the ash becomes molten slag through the pyrolysis residue 43. CaO and the silica source contained in the inorganic binder function as a melting point adjuster and a basicity adjuster of the molten slag. The molten slag with adjusted melting point and basicity flows down through the coke packed layer 41 at the furnace bottom 46 and is discharged from the slag notch 49.

[0022] The maximum temperature of the melting furnace 40 may be, for example, 1600°C or higher in the combustion and melting zone 40c. Since the solid fuel charged from the charging device 50 has sufficient strength in a high-temperature environment, it can maintain its shape for a while after being introduced into the melting furnace 40. During this period, since the pulverization of the solid fuel is suppressed, the scattering of the inorganic binder is suppressed. As a result, CaO contained in the inorganic binder of the solid fuel functions sufficiently as a melting point adjuster and basicity adjuster of the molten slag. The composition of the solid fuel charged from the charging device 50 and the amount of auxiliary materials may be adjusted so that the basicity (CaO / SiO2) of the molten slag discharged from the slag discharge port 49 of the melting furnace 40 is, for example, 0.7 to 1.0. Thereby, molten slag with excellent fluidity is discharged from the slag discharge port 49.

[0023] The slag discharge of the molten slag from the slag discharge port 49 may be performed continuously (continuous slag discharge) or intermittently (intermittent slag discharge). The interval of slag discharge during intermittent slag discharge may be, for example, 30 minutes or more, or 1 hour or more. The molten slag discharged from the slag discharge port 49 may be introduced into a water granulation tank containing cooling water and granulated.

[0024] In the cupola furnace, the solid fuel of the present embodiment can be used instead of the coke stacked in the furnace body. Pig iron, steel scraps and other metals and solid fuel are charged at a predetermined ratio from above the solid fuel stacked to a certain height. While sending air from the tuyere provided at the lower part of the furnace body, the solid fuel is burned, and the pig iron is melted by the combustion heat. The pig iron is melted in the melting zone in the central part of the furnace body and is led out from the lowest tapping hole. Since the solid fuel has sufficient strength in a high-temperature environment, a stable bed can be formed in the furnace body. Since CaO contained in the solid fuel functions as a melting point adjuster, the amount of auxiliary materials such as limestone can be reduced.

[0025] The inorganic binder may contain Portland cement as specified in JIS R 5210:2009. Such solid fuels can have sufficiently high strength in high-temperature environments while significantly reducing manufacturing costs. Examples of Portland cement include ordinary Portland cement, rapid-hardening Portland cement, ultra-rapid-hardening Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement. The CaO content in Portland cement can be measured in accordance with the "Chemical Analysis Method for Cement" in JIS R 5202:2010. By including Portland cement in the inorganic binder, the hot strength of the solid fuel can be sufficiently increased.

[0026] The inorganic binder may contain components other than Portland cement. Examples include clay and sodium silicate. Examples of clay include bentonite (montmorillonite) and kaolin. If the inorganic binder contains multiple components, the total CaO content of the inorganic binder as a whole should be within the range described above.

[0027] The inorganic binder content in solid fuel may be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more. Such solid fuels have even higher strength in high-temperature environments. The inorganic binder content in solid fuel may be 45% by mass or less, 40% by mass or less, or 35% by mass or less. By reducing the inorganic binder content, the biomass char content can be increased, and the calorific value of the solid fuel can be sufficiently increased.

[0028] Solid fuels may contain components other than biomass char and inorganic binders. Examples of such components include powdered coke and organic binders. By including powdered coke in the solid fuel, the powdered coke can be effectively utilized as a heat source. Examples of organic binders include polyvinyl alcohol, carboxymethylcellulose, and starch. The inclusion of organic binders can increase the cold strength of the solid fuel (molded body), thereby improving handling immediately after molding.

[0029] Solid fuel is a molded body obtained by compression molding. There are no restrictions on the size of individual molded bodies, for example, 1 to 800 cm². 3 , 3-600cm 3 , or 50-200cm 3 This is acceptable. When solid fuel of this size is used as fuel for a gasification melting furnace and a cupola, it can form a suitable grate, thereby ensuring a sufficiently stable combustion state within the furnace.

[0030] The hot strength of the solid fuel is preferably 300N or more, more preferably 500N or more, even more preferably 800N or more, and particularly preferably 1000N or more. Such solid fuel can maintain a sufficiently high strength in high-temperature environments. For example, when used as solid fuel for gasification melting furnaces and cupolas, it can form a suitable grate and ensure a sufficiently stable combustion state within the furnace.

[0031] The hot and cold strengths described herein are measured by the following procedure. The solid fuel is heated in an electric furnace in air at 1000°C for 30 minutes. After that, it is cooled to room temperature (approximately 20°C) in a nitrogen atmosphere. If the solid fuel is cylindrical, after cooling, as shown in Figure 2, the solid fuel (sample 10) is placed on the measuring stand 20 and a load is applied in the direction of the arrow (radial direction). The load at which a crack or fracture occurs in the sample 10 is defined as the hot strength (N). Solid fuels with high hot strength have sufficiently high strength in high-temperature environments. Alternatively, using another sample 10, without heating in an electric furnace, a load is applied as shown in Figure 2, and the load at which a crack or fracture occurs in the sample 10 is defined as the cold strength (N).

[0032] Since the solid fuel of this embodiment contains biomass char, it can reduce the consumption of fossil fuels and thus reduce carbon dioxide emissions. By using it as fuel for gasification and melting furnaces and cupolas, the melting point of the slag can be adjusted. In addition, the amount of limestone used as an auxiliary material can be reduced.

[0033] A method for producing solid fuel according to one embodiment includes: a carbonization step of carbonizing biomass by carbonization to obtain biomass char with fixed carbon content of 85% by mass or more on an anhydrous, ash-free basis; a crushing step of crushing the biomass char; a molding step of kneading a molding raw material containing the crushed biomass char, an inorganic binder having a CaO content of 50% by mass or more in a dry state, and water, and molding; and a curing step of curing the molded body. The solid fuel obtained by this manufacturing method may be the solid fuel described in the above embodiment. Therefore, the contents described for solid fuel also apply to this manufacturing method.

[0034] The carbonization process may be carried out by heating the biomass to a carbonization temperature of 200°C or higher in an oxygen-free atmosphere. The ease with which biomass carbonization proceeds varies depending on the tree species and part of the tree. From the viewpoint of ensuring stable and smooth carbonization regardless of the tree species and part of the tree, carbonization may be carried out by heating the biomass to 250°C or higher, or to 320°C or higher. From the viewpoint of increasing the yield of carbon material, the carbonization process may be carried out by heating the biomass to 900°C or lower, or to 700°C or lower. That is, an example of a carbonization temperature is 200 to 900°C.

[0035] In the carbonization process, the heating time within the above temperature range may be 20 minutes or more, or 30 minutes or more, from the viewpoint of sufficiently carbonizing the biomass. In the carbonization process, the heating time within the above temperature range may be 3 hours or less, or 2 hours or less, from the viewpoint of improving the productivity of biomass carbon. The fixed carbon of the biomass carbon can be adjusted by changing the carbonization temperature and carbonization time.

[0036] In the grinding process, the particle size of the biomass char is adjusted. Grinding may be performed using a grinding mill. The particle size of the biomass char may be adjusted to the range described above. Performing the grinding process after the carbonization process allows for smoother grinding.

[0037] In the molding process, a molding raw material is prepared by mixing and kneading biomass char, an inorganic binder, water, and other optional components. Optional components include powdered coke, an organic binder, and an inorganic substance different from the inorganic binder. In the molding raw material, the mass ratio of water to the inorganic binder may be 0.5 or higher, 0.7 or higher, or 1.0 or higher. This allows for sufficiently high strength of the solid fuel. Similarly, the mass ratio of water to the inorganic binder may be 3.0 or lower, 2.5 or lower, or 2.0 or lower. Similarly, the mass ratio of water to the total of biomass char and inorganic binder may be 15-65%, 20-60%, or 25-55%. This allows the inorganic binder to harden sufficiently even if the biomass char absorbs some of the water. After kneading, the molding raw material is molded to obtain a molded body. Molding can be performed using a uniaxial press molding machine or a conventional molding machine such as a briquette roll.

[0038] In the curing process, the inorganic binder contained in the molded body is hardened to obtain solid fuel. Appropriate curing conditions should be selected depending on the type of inorganic binder. For example, if the inorganic binder is Portland cement, curing may be performed by holding it at 20-50°C for 4 hours or more, 6 hours or more, 10 hours or more, or 24 hours or more.

[0039] A drying process may be carried out after the curing process. Drying may be performed in an atmosphere at a higher temperature than that of the curing process. This reduces the moisture content in the inorganic binder, making it possible to obtain a solid fuel with even higher strength.

[0040] The solid fuel obtained by the manufacturing method of this embodiment has sufficient strength in high-temperature environments. Therefore, it is useful, for example, as fuel for gasification and melting furnaces or cupolas. In this case, the melting point of the slag can be adjusted. In addition, the amount of limestone used as an auxiliary material can be reduced. Furthermore, since biomass char is used, the consumption of fossil fuels can be reduced, thereby reducing carbon dioxide emissions.

[0041] While exemplary embodiments of the present disclosure have been described above, the disclosure is not limited to these embodiments. The applications of solid fuels are not limited to gasification and melting furnaces and cupolas. The disclosure includes the following embodiments.

[0042] [1] A solid fuel comprising a biomass char with a fixed carbon content of 85% by mass or more on an anhydrous, ash-free basis, and an inorganic binder with a CaO content of 50% by mass or more in a dry state. [2] The solid fuel according to [1], wherein the biomass carbon content is 50% by mass or more and the inorganic binder content is 15% by mass or more. [3] A solid fuel as described in [1] or [2], wherein the hot strength measured after heating in air at 1000°C for 30 minutes and then cooling is 1000N or more. [4] The solid fuel according to any one of [1] to [3], wherein the inorganic binder comprises Portland cement. [5] A solid fuel according to any one of [1] to [4], wherein the particle size of the biomass carbon is 10 mm or less. [6] A solid fuel according to any one of [1] to [5], further comprising at least one selected from the group consisting of carboxymethylcellulose, polyvinyl alcohol, starch, sodium silicate, and clay. [7] A solid fuel as described in any one of [1] to [6], further comprising powdered coke. [8] A solid fuel according to any one of [1] to [7], which is for use in a gasification melting furnace or cupola and has a function for adjusting the melting point of slag. [9] A method for producing solid fuel, comprising the step of kneading and molding a molding raw material containing biomass char with a fixed carbon content of 85% by mass or more on an anhydrous, ash-free basis, an inorganic binder with a CaO content of 50% by mass or more in a dry state, and water.

[10] The solid fuel according to [9], wherein the particle size of the biomass carbon is 10 mm or less.

[11] A method for producing a solid fuel according to [9] or

[10] , wherein the inorganic binder comprises Portland cement.

[12] A method for manufacturing a solid fuel according to any one of [9] to

[11] , wherein the hot strength of the solid fuel is 1000 N or more.

[13] A method for producing a solid fuel according to any one of [9] to

[12] , wherein the mass ratio of water to the inorganic binder in the molding raw material is 0.5 or more.

[14] The method for producing a solid fuel according to any one of [9] to

[13] , wherein the molding raw material further comprises at least one selected from the group consisting of carboxymethylcellulose, polyvinyl alcohol, sodium silicate, and clay.

[15] The method for producing solid fuel according to any one of [9] to

[14] , wherein the molding raw material further comprises powdered coke. [Examples]

[0043] The contents of this disclosure will be described in more detail below with reference to examples and comparative examples. However, this disclosure is not limited to the following examples.

[0044] [Effects of fixed carbon in biomass char] (Examples 1-4, Comparative Examples 1-4) Acacia and pine chips were prepared as biomass. Each chip was heated in an electric furnace in an oxygen-free atmosphere at approximately 700°C for 30 minutes by dry distillation, and then cooled under a nitrogen gas atmosphere. In this way, eight types of biomass chars with different fixed carbon contents were obtained. Each biomass char was pulverized using a powder mill (CGOLDENWALL, model number: HC-2500) to adjust the particle size to 1 mm or less.

[0045] Industrial analysis of each biomass char was performed in accordance with JIS M 8812:2006 "Coal and coke - Industrial analytical methods". The results are shown in Table 1. The measured values ​​for fixed carbon and volatile matter are based on an anhydrous, ash-free basis.

[0046] Each biomass char, with a particle size adjusted to 1 mm or less, was mixed with commercially available rapid-hardening Portland cement (manufactured by Tokuyama Corporation) in a mass ratio of 70:30, and water was added and kneaded. The CaO content of the rapid-hardening Portland cement was 65% by mass. At this time, the mass ratio of water to rapid-hardening Portland cement (water addition rate) was 1.1. After kneading, a cylindrical molded body (diameter × height = 50 mm × 50 mm) was produced using a uniaxial press molding machine. This molded body was cured at 40°C for 1 day to obtain solid fuel.

[0047] The solid fuel was placed in an electric furnace and heated in air at 1000°C for 30 minutes. It was then cooled to approximately 20°C under a nitrogen atmosphere. This solid fuel (sample 10) was placed on a measuring stand 20 as shown in Figure 2, and a load was applied in the direction of the arrow (radial direction). The strength at the point when cracks or fractures occurred was measured. The measurement results are shown in the "Hot Strength" column of Table 1.

[0048] [Table 1]

[0049] As shown in Table 1, it was confirmed that solid fuels with high hot strength can be obtained by using biomass char with a high fixed carbon content.

[0050] [Effect of inorganic binder content] (Examples 5-7) Solid fuel was prepared in the same manner as in Example 2, except that the mixing ratio of each biomass char to commercially available rapid-strength Portland cement was changed as shown in Table 2, and the hot strength of the solid fuel was measured. The results are shown in Table 2. For comparison, the results of Example 2 are also shown in Table 2.

[0051] (Examples 8-10) Solid fuel was prepared in the same manner as in Example 4, except that the mixing ratio of each biomass char to commercially available rapid-strength Portland cement was changed as shown in Table 2, and the hot strength of the solid fuel was measured. The results are shown in Table 2. For comparison, the results of Example 4 are also shown in Table 2.

[0052] [Table 2]

[0053] As shown in Table 2, it was confirmed that the hot strength could be increased by increasing the proportion of inorganic binder (early-strength Portland cement). By increasing the inorganic binder content in the solid fuel to 15% by mass or more, the hot strength of the solid fuel could be increased to 1000N or more.

[0054] [Effect of particle size in biomass char] (Examples 11-14) Solid fuel was prepared in the same manner as in Example 2, except that the sieve used for screening the biomass char was changed and biomass char with particle sizes as shown in Table 3 was used. The hot strength of the solid fuel was then measured. The results are shown in Table 3. For comparison, the results from Example 2 are also shown in Table 3.

[0055] (Examples 15-18) By varying the grinding time in a powder mill, biomass char with particle sizes as shown in Table 3 was prepared. Solid fuel was prepared in the same manner as in Example 4, except for the use of biomass char with these particle sizes, and the hot strength of the solid fuel was measured. The results are shown in Table 3. For comparison, the results from Example 4 are also shown in Table 3.

[0056] [Table 3]

[0057] As shown in Table 3, it was confirmed that the hot strength of the solid fuel could be adjusted by changing the particle size of the biomass char. The solid fuel with the highest hot strength was obtained when the particle size of the biomass char was 1 mm or less.

[0058] [Effect of water addition rate] (Examples 19-23) Solid fuel was prepared in the same manner as in Example 13, except that the mass ratio of water to high-early-strength Portland cement (water addition rate) was changed as shown in Table 4, and the hot strength of the solid fuel was measured. The results are shown in Table 4. For comparison, the results of Example 13 are also shown in Table 4.

[0059] (Examples 24-28) Solid fuel was prepared in the same manner as in Example 2, except that the mass ratio of water to rapid-hardening Portland cement (water addition rate) was changed as shown in Table 4, and the hot strength of the solid fuel was measured. The results are shown in Table 4. For comparison, the results of Example 2 are also shown in Table 4.

[0060] [Table 4]

[0061] In Table 4, "Moisture content" refers to the mass ratio of water to the total of biomass char and rapid-hardening Portland cement. As shown in Table 4, it was confirmed that the hot strength increased as the water addition rate increased to 1.1 and the moisture content increased to approximately 33% by mass.

[0062] [Influence of inorganic binder type and curing conditions] (Examples 29-31) Solid fuel was prepared in the same manner as in Example 2, except that the curing time of the molded body at 40°C was changed as shown in Table 5, and the hot strength of the solid fuel was measured. The results are shown in Table 5. For comparison, the results of Example 2 are also shown in Table 5.

[0063] (Examples 32-34) Except for using commercially available ordinary Portland cement (manufactured by Tokuyama Corporation) instead of rapid-hardening Portland cement, and changing the curing time of the molded body at 40°C as shown in Table 5, solid fuel was prepared in the same manner as in Example 2, and the hot strength of the solid fuel was measured. The results are shown in Table 5.

[0064] [Table 5]

[0065] The results in Table 5 confirm that even if the inorganic binder is ordinary Portland cement, a solid fuel with sufficient strength in a high-temperature environment can be obtained by extending the curing time.

[0066] [Effects of additives] (Examples 35-41) The following additives were prepared. All are commercially available products. • Polyvinyl alcohol Carboxymethylcellulose ·starch Bentonite Kaolin • Frogeye clay Sodium silicate

[0067] The biomass char used in Example 2 and commercially available rapid-hardening Portland cement were mixed in a mass ratio of 70:30, and water was added and kneaded. At this time, the above additives were added in the addition ratios shown in Table 6. The addition ratios shown in Table 6 are the mass ratios to the total of biomass char and rapid-hardening Portland cement. The mass ratio of water to rapid-hardening Portland cement (water addition rate) was set to 1.1. Solid fuel was prepared in the same manner as in Example 2, except for the use of these molding raw materials, and the hot strength of the solid fuel was measured. The results are shown in Table 6. Example 2A in Table 6 is a solid fuel prepared using the same procedure as in Example 2, but without the addition of additives.

[0068] In each example, the strength of the molded article was also measured immediately after molding and before curing at 40°C for one day. The results of this strength measurement are shown in Table 7 as "cold strength". The units of the values ​​in Tables 6 and 7 are "N".

[0069] Cold strength is the strength measured immediately after molding, without any heat treatment. Similar to hot strength, the molded body (sample 10) was placed on the measuring stand 20 as shown in Figure 2, and the strength was measured at the point when a crack or fracture occurred after applying a load in the direction of the arrow (radial direction).

[0070] [Table 6]

[0071] [Table 7]

[0072] As shown in Table 6, there was no significant change in hot strength even with the addition of additives. On the other hand, as shown in Table 7, it was confirmed that the cold strength could be significantly improved by including additives. This improves the handling properties until the inorganic binder hardens. In particular, it was found that the cold strength was especially high when polyvinyl alcohol, a type of organic binder, was added. [Explanation of symbols]

[0073] 10...Sample, 20...Measurement stand, 40...Melting furnace, 40a...Drying / pre-heating zone, 40b...Pyrolysis zone, 40c...Combustion / melting zone, 41...Coke packed bed, 42...Shaft section, 43...Pyrolysis residue, 44...Cricket section, 45...Upper tuyere, 46...Furnace bottom, 47...Lower tuyere, 48...Waste, 49...Slag outlet, 50...Charging device, 52...Exhaust gas pipe, 100...Waste melting treatment equipment.

Claims

1. A solid fuel containing biomass char, wherein the hot strength measured after heating in air at 1000°C for 30 minutes and then cooling is 1000N or more, The inorganic binder contains a CaO content of 50% by mass or more in a dry state. solid fuel.

2. The biomass char content is 50% by mass or more, and the inorganic binder content is 15% by mass or more. The solid fuel according to claim 1.

3. The inorganic binder contains Portland cement, The solid fuel according to claim 1 or 2.

4. The particle size of the biomass char is 10 mm or less. The solid fuel according to claim 1 or 2.

5. It further comprises at least one selected from the group consisting of carboxymethylcellulose, polyvinyl alcohol, starch, sodium silicate, and clay. The solid fuel according to claim 1 or 2.

6. The solid fuel according to claim 1 or 2, further comprising powdered coke.

7. The solid fuel according to claim 1 or 2, which is for use in a gasification melting furnace or cupola and has a function for adjusting the melting point of slag.

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