Manufacturing method of solid fuel

Abstract

To provide a method for manufacturing solid fuel that allows for easy handling of heat-treated materials and offers excellent workability. [Solution] A method for producing solid fuel comprising a heating step of heating waste raw materials containing waste plastic in a heating furnace to thermally decompose at least a portion of the waste plastic, wherein the waste raw materials mainly consist of thermoplastic plastic, and the mass ratio of particles having a particle size of 5 mm or more in the heat-treated product obtained in the heating step is 80% by mass or more.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing solid fuel.

Background Art

[0002] Various techniques for producing solid fuel by heat-treating waste including waste plastics have been studied (Patent Documents 1 and 2). In Patent Document 1, an attempt has been made to produce solid fuel with reduced chlorine by heating the waste to embrittle it, pulverizing it, and then performing air classification. In Patent Document 2, a technique has been proposed for producing solid fuel having an average particle size within a predetermined range by heating waste containing plastic waste in a heating step to embrittle it and then performing a crushing step and a pulverizing step.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When waste containing waste plastics is heated in a heating furnace, the plastic component becomes embrittled and fine particles are generated. When the particle size becomes small, dust is likely to be generated during subsequent processes and transportation, and handling requires caution, resulting in a decrease in workability. Therefore, the present disclosure provides a method for manufacturing solid fuel that can obtain a heat-treated product that is easy to handle and has excellent workability.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a method for manufacturing solid fuel having a heating step of heating a waste raw material containing waste plastics in a heating furnace to thermally decompose at least a part of the waste plastics, The aforementioned waste material contains thermoplastic plastic as its main component. The present invention provides a method for producing solid fuel, wherein the mass ratio of particles having a particle size of 5 mm or larger in the heat-treated product obtained in the aforementioned heating step is 80% by mass or more.

[0006] In the above manufacturing method, the waste material heated in the furnace contains thermoplastic plastic as its main component. With such waste materials, the thermoplastic plastic fuses together, making it easy to obtain a heat-treated product with large particle sizes. Since the mass ratio of particles with a particle size of 5 mm or larger is 80% by mass or more in this heat-treated product, the mass ratio of fine particles is sufficiently reduced. Therefore, the above manufacturing method makes it possible to obtain a heat-treated product that is easy to handle and has excellent workability because it suppresses the generation of dust during subsequent processes and transportation. [Effects of the Invention]

[0007] According to this disclosure, it is possible to obtain a heat-treated product that is easy to handle and to provide a method for manufacturing solid fuel with excellent workability. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing an example of a solid fuel manufacturing apparatus. [Figure 2] (A) is a photograph showing the waste material used in Example 1. (B) is a photograph showing the waste material used in Comparative Example 1. [Figure 3] This graph shows the particle size distribution of the solid fuels in Example 1 and Comparative Example 1. [Figure 4] This graph shows the particle size distribution of the solid fuels in Examples 2 and 3 and Comparative Examples 2 and 3. [Figure 5] (A) is a photograph of the solid fuel from Example 1, (B) is a photograph of the solid fuel from Comparative Example 1, (C) is a photograph of the solid fuel from Example 2, and (D) is a photograph of the solid fuel from Comparative Example 2. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described below, with reference to drawings as appropriate. However, the following embodiments are illustrative for the purpose of illustrating this disclosure and are not intended to limit this disclosure to the following. In the description, positional relationships such as up, down, left, and right refer to positional relationships based on the orientation of the reference numerals in the drawings, unless otherwise specified. The dimensional ratios of each element are not limited to the ratios shown. In the description, the symbol "~" used in numerical ranges indicates a numerical range that includes the upper and lower limits. For example, "X~Y" indicates a numerical range of "X or greater and Y or less". Numerical ranges in which the upper and / or lower limits of a numerical range are replaced with the values ​​described in the embodiments are also included in this disclosure. If a numerical range is illustrated with only the upper limit or only the lower limit, a numerical range combining the upper limit-only numerical range and the lower limit-only numerical range is also included in this disclosure. Numerical ranges in which the upper and / or lower limits of one numerical range are replaced with the upper and / or lower limits of another numerical range are also included in this disclosure.

[0010] A method for producing solid fuel according to one embodiment includes a heating step in which waste raw materials containing waste plastic are heated in a heating furnace to thermally decompose at least a portion of the waste plastic. The waste raw materials mainly consist of thermoplastic plastic, and the mass ratio of particles having a particle size of 5 mm or more in the heat-treated product obtained in the heating step is 80% by mass or more.

[0011] The waste raw materials containing waste plastics may be either industrial waste or general waste, and examples include container recycling residue, shredder dust, construction waste plastics, agricultural waste plastics, fishery waste plastics, marine waste plastics, etc. The waste raw materials may also contain foreign matter other than waste plastics. Examples of foreign matter include paper, rubber, wood scraps, metal scraps, metal wires, metal foils, glass scraps, concrete scraps, ceramic scraps, slag, rubble, etc. From the viewpoint of obtaining heat-treated material with large particle size and from the viewpoint of obtaining solid fuel with high added value, the mass percentage of waste plastics in the waste raw materials may be 70% by mass or more, 80% by mass or more, or 90% by mass or more.

[0012] In this disclosure, "main component" refers to the component that is present in the largest amount by mass relative to the total. The thermoplastic content in the waste material may be 50% by mass or more, 65% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. Waste with a high thermoplastic content tends to melt and fuse together when heated, resulting in larger particle size.

[0013] Thermoplastic plastics are plastics manufactured using thermoplastic resins. Thermoplastic plastics may include, for example, at least one selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polyamide, polycarbonate, and acrylic. Thermoplastic plastics may be in the form of fluff, foam, or granules, for example.

[0014] The waste raw materials may include, as by-components, combustible materials such as thermosetting plastics, fibers, paper, cardboard, wood, leather, elastomers, and rubber, as well as non-combustible materials such as metals, ceramics, glass, sand, and stones. However, from the viewpoint of ensuring a sufficiently high calorific value for the solid fuel, the proportion of combustible materials in the waste may be 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more.

[0015] The particle size of the waste material may be less than 100 mm, less than 80 mm, or less than 60 mm. This allows for sufficiently small variations in particle size of the heat-treated material. In this disclosure, "particle size" is based on the size of the sieve opening. Waste material with a particle size of less than 100 mm can be obtained as the residue after sieving using a sieve with a 100 mm opening.

[0016] The waste raw material may contain fluff-shaped plastic as the main component. The fluff-shaped plastic is obtained by crushing film-shaped or sheet-shaped plastic. The fluff-shaped plastic can be smoothly fused by heating to obtain a heat-treated product having a sufficiently large particle size. The size of the fluff-shaped plastic may be such that the mass ratio (the mass ratio of the material passing through the sieve) passing through a sieve with a mesh size of 50 mm is 60% by mass or more, 80% by mass or more, or 90% by mass or more. Thereby, the variation in the size of the heat-treated product can be reduced. The fluff-shaped plastic may contain thermoplastic as the main component. The fluff-shaped plastic may contain thermosetting plastic, ink, adhesive, etc. as sub-components.

[0017] Before the heating step or the mixing step described below, a crushing step of crushing the waste raw material may be performed. Alternatively, before the heating step, a crushing step of crushing the mixed raw material obtained by the mixing step may be performed. The crushing step may be carried out using, for example, a shredder, a granulator, a pulverizer, or the like.

[0018] The content of the thermosetting plastic in the waste raw material may be 8% by mass or less, 6% by mass or less, 4% by mass or less, or 2% by mass or less. It is considered that the thermosetting plastic suppresses the fusion of the thermoplastic by adhering to the surface of the melt of the thermoplastic. Therefore, by reducing the content of the thermosetting plastic, it becomes easier to obtain a heat-treated product with a large particle size that is easy to handle. On the other hand, from the viewpoint of suppressing the particle size of the heat-treated product from becoming too large, the content of the thermosetting plastic in the waste raw material may be 1% by mass or more.

[0019] A thermosetting plastic is a plastic manufactured using a thermosetting resin. The thermosetting plastic may contain at least one selected from the group consisting of, for example, polyurethane, melamine, unsaturated polyester, phenolic resin, urea resin, silicone resin, epoxy resin, and alkyd resin. The form of the thermosetting plastic is not particularly limited, and may be, for example, flaky, foamed, or granular.

[0020] The waste raw material may contain rigid plastic. The rigid plastic in the present disclosure refers to a material having a tensile modulus of elasticity measured in accordance with ASTM D638 of 1000 MPa or more. Rigid plastics are plastics that are excellent in mechanical strength, heat resistance, and chemical resistance and are used in a wide range of fields such as electronic device casings, automotive parts, household goods, and building materials. Rigid plastics may contain at least one selected from the group consisting of, for example, polycarbonate, polypropylene, polystyrene, acrylonitrile-butadiene-styrene, polyamide, polyethylene terephthalate, polyvinyl chloride, polymethyl methacrylate, and polyphenylene sulfide. Since rigid plastics have a higher melting point than soft plastics, they are considered to be more difficult to fuse than soft plastics in the heating process. From the viewpoint of obtaining a heat-treated product with a sufficiently large particle size, the content of rigid plastic in the waste raw material may be 8% by mass or less, 6% by mass or less, 4% by mass or less, or 2% by mass or less. On the other hand, from the viewpoint of suppressing the particle size of the heat-treated product from becoming too large, the content of rigid plastic may be 1% by mass or more.

[0021] The waste material may be introduced separately into the heating furnace and mixed within the furnace, or a mixing step may be performed before the heating step in the heating furnace in which the waste material and the non-waste material are mixed to prepare a mixed material. Examples of non-waste material include pulverized coal. Pulverized coal has the effect of preventing the thermoplastic plastic contained in the waste material from fusing together, but it also has the effect of suppressing the fusion of thermoplastic plastic into the inside of the heating furnace. The mixed material thus obtained may be introduced into the heating furnace. The waste material and pulverized coal may be introduced into the heating furnace separately. The mixing step can be carried out using, for example, a V-type mixer, a W-type mixer, a drum-type mixer, a self-rotating or revolving screw conveyor, a kiln-type dryer, etc.

[0022] The mass ratio of pulverized coal to waste raw material may be 1.0 or less, 0.8 or less, or 0.5 or less, from the viewpoint of obtaining a heat-treated product with sufficiently large particle size. The mass ratio of pulverized coal to waste raw material may be 0.2 or more, 0.3 or more, or 0.5 or more, from the viewpoint of suppressing the fusion of thermoplastic plastic into the inside of the heating furnace. The said mass ratio may be between 0.3 and 1.0.

[0023] Waste materials, non-waste materials, or mixed materials are introduced into a continuous or batch-type heating furnace and heated to 250-500°C, 300-450°C, or 300-400°C. The heating time may be 0.5-3 hours or 1-2 hours. This allows for sufficient thermal decomposition and desalination of waste plastics while producing easily handleable heat-treated materials (solid fuel) with a high yield. The inside of the heating furnace may be an inert gas atmosphere. The heating furnace may be, for example, a rotary kiln equipped with lifter blades. This prevents plastics or their decomposition products from fusing into the inside of the heating furnace.

[0024] The heat-treated material obtained in the heating process tends to have larger particle sizes due to the fusion of thermoplastic plastics. The mass ratio of particles with a particle size of 5 mm or larger in the heat-treated material may be 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass. Such heat-treated materials have excellent workability as dust generation during transportation is sufficiently suppressed. From a similar viewpoint, the mass ratio of particles with a particle size of 16 mm or larger may be 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more.

[0025] From the viewpoint of maintaining excellent workability, facilitating smooth gas transport, and reducing the burden of crushing the heat-treated material, the mass ratio of particles having a particle size of 5 mm or more and less than 40 mm in the heat-treated material may be 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more. Particles having a particle size of 5 mm or more and less than 40 mm are obtained as the sieved portion after the heat-treated material has been sieved through a sieve with a mesh size of 40 mm to obtain the sieved portion, and then the sieved portion is sieved through a sieve with a mesh size of 5 mm.

[0026] The average particle size (Dp50) of the heat-treated material (solid fuel) may be 9.0 mm or larger, 9.5 mm or larger, 10 mm or larger, or 14 mm or larger. The average particle size (Dp50) can be determined by the following procedure: The heat-treated material is sieved to determine the mass ratio in each of the seven particle size ranges: less than 1.0 mm, 1.0 mm or larger but less than 2.0 mm, 2.0 mm or larger but less than 2.8 mm, 2.8 mm or larger but less than 4.7 mm, 4.7 mm or larger but less than 9.5 mm, 9.5 mm or larger but less than 16 mm, and 16 mm or larger. The median of each particle size range is considered to have the mass ratio in that particle size range, and seven data points are obtained. Note that for the particle size ranges of less than 1.0 mm and 16 mm or larger, the respective mass ratios are considered to have particle sizes of 1.0 mm and 16 mm. Using the seven data points, a quadratic function is found that has a correlation coefficient (r) closest to 1. Based on the obtained quadratic function, the average particle size (Dp50) is defined as the particle size at which the cumulative mass ratio from the small particle size side reaches 50% by mass.

[0027] The heat-treated material may be used as solid fuel as is. That is, the solid fuel may have the particle size and average particle size described above. The heat-treated material obtained in the heating process may be crushed after cooling. Crushing may be carried out, for example, using a mill. The heat-treated material can be smoothly conveyed from the heating furnace to the crushing device.

[0028] The above-described method for manufacturing solid fuel may be carried out using, for example, the manufacturing apparatus 100 shown in Figure 1. The manufacturing apparatus 100 in Figure 1 comprises an indirectly heated rotary kiln 10 having a kiln body 12 (inner cylinder) and an outer cylinder 14, an introduction section 50 for introducing raw materials 51 into the kiln body 12 of the rotary kiln 10, and an outlet section 30 for discharging the heated material 53 (solid fuel) from the kiln body 12 of the rotary kiln 10. The introduction section 50 only needs to have a configuration that can transport the raw materials 51, and may include, for example, a conveyor. The raw materials 51 may be waste materials, or a mixed material containing waste materials and pulverized coal. Upstream of the introduction section 50, a mixer for mixing the waste materials and pulverized coal may be provided. In a modified example, the introduction section 50 may introduce the waste materials and pulverized coal separately into the kiln body 12 and mix them within the kiln body 12.

[0029] In the rotary kiln 10, the kiln body 12 has lifter blades inside and is rotatably supported by rollers 15 and 16. Raw material 51 is introduced into the kiln body 12 from the inlet 50. The rotation axis of the kiln body 12 is slightly inclined with respect to the horizontal, with the inlet 50 side being higher than the outlet 30 side. Therefore, the raw material 51 introduced into the kiln body 12 is agitated by the lifter blades as the kiln body 12 rotates, moving from the inlet 50 side to the outlet 30 side. In Figure 1, the raw material 51 moves from left to right inside the kiln body 12.

[0030] In addition to the raw material 51, an inert gas may be introduced into the kiln body 12 of the rotary kiln 10. Examples of inert gases include nitrogen gas and exhaust gas containing carbon dioxide. The inert gas may also move along with the raw material 51 within the kiln body 12 from the upstream side to the downstream side. The raw material 51 is heated within the kiln body 12, causing the waste plastic to melt or carbonize to become a heat-treated product 53. The heat-treated product 53 is discharged from the kiln body 12 to the outlet section 30 and introduced into the cooler 40. After being cooled in the cooler 40, the heat-treated product 53 is discharged from the manufacturing apparatus 100. The heat-treated product 53 discharged from the manufacturing apparatus 100 may be used as solid fuel as is, or it may be crushed in a pulverizer.

[0031] The pyrolysis gas G3 generated by heating the raw material 51 inside the kiln body 12 is discharged from the outlet 32 ​​of the outlet section 30. An outer cylinder 14 is provided around the outer circumference of the kiln body 12. The outer cylinder 14 forms a hot gas flow path 17 that indirectly heats the kiln body 12. Hot gas G1 is supplied to the hot gas flow path 17 formed by the outer cylinder 14 from the gas inlet 21. The hot gas G1 may be exhaust gas from combustion equipment such as a boiler. The temperature of the hot gas G1 may be, for example, 400 to 500°C. The hot gas G1 heats the kiln body 12 by flowing through the hot gas flow path 17. The hot gas G1 that has heated the kiln body 12 is discharged to the outside as exhaust gas G2 from the gas outlet 22. In the manufacturing apparatus 100, the fusion of molten thermoplastic to the inner wall 13 of the kiln body 12 can be suppressed. This allows for stable and continuous operation.

[0032] The manufacturing apparatus used in the solid fuel manufacturing method of this embodiment is not limited to that shown in Figure 1. For example, the manufacturing apparatus may be a batch furnace equipped with lifter blades. In the manufacturing method of this embodiment, thermoplastic plastics are fused together to obtain a heat-treated product with a large particle size. As a result, the heat-treated product is easy to handle, and excellent workability can be achieved. In addition, the amount of pulverized coal used as an anti-fusing agent derived from coal can be reduced. This can also promote decarbonization.

[0033] The above-described embodiment includes the following: [1] A method for producing a solid fuel, comprising a heating step of heating waste raw materials including waste plastic in a heating furnace to thermally decompose at least a portion of the waste plastic, The aforementioned waste material contains thermoplastic plastic as its main component. A method for producing a solid fuel, wherein the mass ratio of particles having a particle size of 5 mm or larger in the heat-treated product obtained in the heating step is 80% by mass or more. [2] The method for producing solid fuel according to [1], wherein the waste material comprises fluff-shaped plastic as the main component. [3] The method for producing a solid fuel according to [1] or [2], wherein the heat-treated product has a mass ratio of 80% by mass or more of particles having a particle size of 5 mm or more and less than 40 mm. [4] A method for producing solid fuel according to any one of [1] to [3], wherein the content of thermosetting plastic in the waste raw material is 8% by mass or less. [5] A method for producing solid fuel according to any one of [1] to [4], wherein the hard plastic content in the waste raw material is 8% by mass or less. [6] A method for producing solid fuel according to any one of [1] to [5], wherein the average particle size of the heat-treated material is 9.0 mm or more. [7] Prior to the heating step, the mixing step is to prepare a mixed raw material containing the waste raw material and pulverized coal, A method for producing solid fuel according to any one of [1] to [6], wherein the heating step involves introducing the mixed raw materials into the heating furnace. [8] The method for producing solid fuel according to [7], wherein the mass ratio of pulverized coal to the waste raw material is 1.0 or less.

[0034] This disclosure is not limited to the embodiments described above. [Examples]

[0035] The contents of this disclosure will be explained in more detail below with reference to examples and comparative examples. However, this disclosure is not limited to the examples described below.

[0036] (Example 1) Waste materials, primarily composed of fluff plastic, were crushed in a crusher to prepare waste raw materials (particle size: <50 mm, Figure 2(A)). Manual sorting determined that thermoplastic plastic (fluff) accounted for 95.2% by mass in these waste raw materials, while fibers, paper, and wood chips accounted for 4.8% by mass. This waste raw material was mixed with commercially available pulverized coal (Dp50: 3.6 mm) in a 1:1 mass ratio to prepare a mixed raw material. This mixed raw material was introduced into a heating furnace equipped with lifter blades and heated while circulating inert gas. The heating rate was increased from room temperature to 200°C at a rate of 6°C / min, and from 200°C to 320°C at a rate of approximately 2°C / min. The heating furnace rotation speed was set to 1.9 rpm. The plastics contained in the mixed raw material melted and / or thermally decomposed, and the furnace temperature reached 350°C. After holding for 1 hour, heating was stopped and the material was allowed to cool, and the heat-treated material was removed from the heating furnace. In this manner, the solid fuel (heat-treated material) of Example 1 was obtained. The particle size of the solid fuel was examined using a sieve. The average particle size (Dp50) was also determined from the particle size distribution. The results are shown in Table 1 and Figure 3. The method for deriving the average particle size (Dp50) is as described above.

[0037] (Comparative Example 1) Waste materials mainly composed of fluff-like plastic, different from that used in Example 1, were crushed in a crusher to prepare waste raw materials (particle size: <50 mm, Figure 2(B)). The proportion of thermoplastic plastic (fluff) in these waste raw materials, determined by manual sorting, was 60.5% by mass, and the other compositions were as shown in Table 1. These waste raw materials and the pulverized coal used in Example 1 were mixed in a 1:1 mass ratio to prepare a mixed raw material. Except for using this mixed raw material, heating was carried out in a heating furnace in the same manner as in Example 1 to obtain the solid fuel (heat-treated product) of Comparative Example 1. The particle size of the solid fuel was examined in the same manner as in Example 1. The results are shown in Table 1 and Figure 3.

[0038] (Example 2) The waste material used in Example 1, granular polystyrene foam (particle size: approximately 20-30 mm) obtained by cutting commercially available polystyrene foam, and pulverized coal were mixed in a mass ratio of 89.3:10.7:100 to obtain a mixed raw material. Except for using this mixed raw material, heating in a heating furnace was carried out in the same manner as in Example 1 to obtain the solid fuel (heat-treated product) of Example 2. The particle size of the solid fuel was examined in the same manner as in Example 1. The results are shown in Table 1 and Figure 4.

[0039] (Example 3) The waste material used in Example 1, granular polyurethane (particle size: approximately 20-30 mm) obtained by cutting commercially available polyurethane, and pulverized coal were mixed in a mass ratio of 94.5:5.5:100 to obtain a mixed raw material. Except for using this mixed raw material, heating in a heating furnace was carried out in the same manner as in Example 1 to obtain the solid fuel (heat-treated product) of Example 3. The particle size of the solid fuel was examined in the same manner as in Example 1. The results are shown in Table 1 and Figure 4.

[0040] (Comparative Example 2) The waste material used in Example 1, the polyurethane granules used in Example 3, and pulverized coal were mixed in a mass ratio of 89.3:10.7:100 to obtain a mixed raw material. Except for using this mixed raw material, heating was carried out in a heating furnace in the same manner as in Example 1 to obtain the solid fuel (heat-treated product) of Comparative Example 2. The particle size distribution of the solid fuel was examined in the same manner as in Example 1. The results are shown in Table 1 and Figure 4.

[0041] (Comparative Example 3) The waste raw materials used in Example 1, granular hard plastic (particle size: approximately 20 mm) obtained by separating waste mainly composed of fluff-like plastic, and pulverized coal were mixed in a mass ratio of 89.3:10.7:100 to obtain a mixed raw material. Except for using this mixed raw material, heating was carried out in a heating furnace in the same manner as in Example 1 to obtain the solid fuel (heat-treated product) of Comparative Example 3. The particle size distribution of the solid fuel was examined in the same manner as in Example 1. The results are shown in Table 1 and Figure 4.

[0042] [Table 1]

[0043] Table 1 shows the ratio of components in the waste raw materials. Figure 5(A) shows photographs of the solid fuel from Example 1, Figure 5(B) from Comparative Example 1, Figure 5(C) from Example 2, and Figure 5(D) from Comparative Example 2. From the comparison between Example 1 (Figure 5(A)) and Comparative Example 1 (Figure 5(B)), it was confirmed that a lower ratio of thermosetting plastics and rigid plastics, and a higher ratio of fluff-like plastics, allowed for a larger particle size in the heat-treated material (solid fuel). A similar trend was observed in Example 3, Comparative Example 2, and Comparative Example 3.

[0044] A comparison of Example 2 (Figure 5(C)) and Comparative Example 2 (Figure 5(D)) confirmed that the particle size of the heat-treated material (solid fuel) was smaller when thermosetting plastic was added than when thermoplastic plastic was added. The reason why the particle size of the heat-treated material (solid fuel) in Example 2 (Figure 5(C)) was smaller than that of Example 1 (Figure 5(A)) is thought to be that foamed plastic is less likely to fuse with fluff plastic, thus preventing the particle size from becoming larger. [Explanation of Symbols]

[0045] 10...Rotary kiln, 12...Kiln body, 14...Outer cylinder, 15,16...Rollers, 17...Hot gas flow path, 21...Gas inlet, 22...Gas outlet, 30...Outlet section, 32...Outlet section, 40...Cooler, 50...Inlet section, 51...Raw material, 53...Heated product, 100...Manufacturing equipment.

Claims

1. A method for producing a solid fuel, comprising a heating step of heating waste raw materials including waste plastic in a heating furnace to thermally decompose at least a portion of the waste plastic, The aforementioned waste material contains thermoplastic plastic as its main component. A method for producing a solid fuel, wherein the mass ratio of particles having a particle size of 5 mm or larger in the heat-treated product obtained in the heating step is 80% by mass or more.

2. The method for producing solid fuel according to claim 1, wherein the waste material mainly contains fluff-shaped plastic.

3. The method for producing a solid fuel according to claim 1 or 2, wherein the heat-treated product has a mass ratio of 80% by mass or more of particles having a particle size of 5 mm or more and less than 40 mm.

4. A method for producing solid fuel according to claim 1 or 2, wherein the content of thermosetting plastic in the waste raw material is 8% by mass or less.

5. A method for producing solid fuel according to claim 1 or 2, wherein the content of hard plastic in the waste raw material is 8% by mass or less.

6. The method for producing solid fuel according to claim 1 or 2, wherein the average particle size of the heat-treated material is 9.0 mm or more.

7. Prior to the heating step, there is a mixing step of preparing a mixed raw material containing the waste raw material and pulverized coal, The method for producing solid fuel according to claim 1 or 2, wherein the heating step involves introducing the mixed raw materials into the heating furnace.

8. The method for producing solid fuel according to claim 7, wherein the mass ratio of the pulverized coal to the waste raw material is 1.0 or less.

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