Method for manufacturing solid fuel and solid fuel

Abstract

We provide solid fuel that has been designed to prevent odor leakage. [Solution] A manufacturing method is provided that provides a solid fuel (80) with measures to prevent odor leakage, comprising: a crushing step (ST01) in which a mixture of waste plastic (11) and waste paper (12) is crushed to a predetermined size using a crusher to obtain crushed material (27); a compression and sizing step (ST02) in which the crushed material (27) is compressed using an extrusion molding machine or ring die, melted by frictional heat, and sizing to a predetermined outer diameter and length to obtain columnar material (66); and a resin coating step (ST03) in which the outer surface of the columnar material (66) is covered with a resin film (81) using a resin coating mechanism to obtain a solid fuel (80) with measures to prevent odor leakage.

Description

Technical Field

[0001] The present invention relates to solid fuel with measures to prevent odor leakage.

Background Art

[0002] With the increasing demand for plastics, it is desirable to effectively utilize discarded plastics (hereinafter referred to as waste plastics). As methods of effective utilization, three methods are known: material recycling, chemical recycling, and thermal recycling.

[0003] Material recycling is a technology for manufacturing new plastic products using waste plastics as raw materials as they are. A typical example is melting old PET bottles to obtain new PET bottles.

[0004] Chemical recycling is a technology for reforming waste plastics into petroleum or naphtha through chemical treatment. Although it is an ideal technology, it has difficulties in terms of cost. Thermal recycling is a technology for burning waste plastics to convert them into thermal energy. It can save petroleum and coal as fuels.

[0005] According to "Basic Knowledge of Plastic Recycling 2024" (published by the Plastic Recycling Association, a general incorporated foundation), when the total processing volume of the above three recycling methods is 87%, "material recycling" accounts for 22%, "chemical recycling" accounts for 3%, and "thermal recycling" accounts for 62%. This trend has hardly changed in recent years.

[0006] Technologies related to thermal recycling, which accounts for the majority, have been proposed in various ways conventionally (for example, refer to Patent Document 1 (Figure 1)).

[0007] Patent Document 1 will be described based on the following figure. Figure 12 is a perspective view of a conventional solid fuel. The solid fuel 100 consists of crushed waste plastic 101 and 20-30% by weight of recycled paper 102. Its outer diameter is approximately 40 mm and its length is approximately 30-100 mm.

[0008] Using only waste plastic 101 would generate too much heat, damaging combustion equipment such as boilers. Mixing in waste paper 102 would moderately reduce the heat output. This allows for more effective utilization of waste plastic 101 and waste paper 102 than simply landfilling or incinerating them.

[0009] However, in recent years, with the promotion of environmental hygiene improvements, the odor emitted from solid fuel 100 has come to be a cause for concern. In other words, as shown in Figure 12, the waste paper 102 is partially exposed on the surface. Moisture from the atmosphere seeps into the waste paper 102. Alternatively, moisture penetrates through the tiny gaps at the boundary between the waste paper 102 and the waste plastic 101.

[0010] Furthermore, waste plastics 101 and waste paper 102 inevitably have impurities attached to them. When these impurities become damp, the organic matter they contain decomposes and generates an odor. This putrid odor leads to a deterioration of the environment around the storage area and combustion equipment for solid fuel 100. Therefore, odor control measures targeting solid fuel 100 are desirable. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 7-118673 [Overview of the project] [Problems that the invention aims to solve]

[0012] The object of this invention is to provide a solid fuel that has been designed to prevent odor leakage. [Means for solving the problem]

[0013] The inventors of this invention considered the following as countermeasures against odor. First, we considered adding deodorizers and preservatives to a mixture of waste plastic 101 and waste paper 102. Some effect can be expected from these deodorizers and preservatives. However, this method has the drawback of increasing the cost of procuring deodorizers and preservatives. In addition, it is necessary to limit the selection of deodorizers and preservatives to those that do not produce harmful gases when burned, which also has the drawback of narrowing the range of choices available.

[0014] Next, we considered encasing the solid fuel 100 in a resin coating. This was a measure to prevent odor leakage, as the odor of the solid fuel 100 itself was tolerable, but this odor would not escape. Resin coatings have the advantage of being cheaper than deodorizers and preservatives. In addition, with the exception of polyvinyl chloride, most resins do not produce harmful gases when burned, which broadens the range of resins that can be selected.

[0015] Therefore, the inventors of this invention conducted research on odor leakage countermeasures using resin coatings and have completed the present invention.

[0016] In other words, the invention according to claim 1 is a crushing step of crushing a mixture of waste plastic and waste paper to a predetermined size using a crusher to obtain crushed material, A melting and solidification step is performed in which the crushed material is compressed by an extrusion molding machine or ring die and melted by frictional heat to obtain a columnar object with a predetermined outer diameter, The present invention provides a method for manufacturing solid fuel, comprising a resin coating step, in which the outer surface of the columnar object is covered with a resin film by a resin coating mechanism to obtain solid fuel in which measures have been taken to prevent odor leakage.

[0017] Furthermore, the inventors considered coating the solid fuel 100 with a surfactant film. This method allows the odor of the solid fuel 100 itself to be tolerated, but prevents this odor from escaping. By coating the solid fuel 100 with a surfactant, we were able to prevent odor leakage. Surfactants are included in dishwashing detergents and laundry detergents and are harmless to the human body if used in appropriate amounts, so they are suitable for the coating of solid fuels. In addition, surfactants are easily available and inexpensive, so there is an advantage that the increase in the manufacturing cost of solid fuels can be suppressed. The invention based on this finding is as follows.

[0018] The invention according to claim 2 comprises a crushing step of crushing a mixture of waste plastic and waste paper into a predetermined size by a crusher to obtain a crushed product, a compression-sizing step of compressing the crushed product by an extrusion molding machine or a ring die, melting it with frictional heat, and sizing it to a predetermined outer diameter and length to obtain a columnar product, and a resin coating step of covering the outer surface of the columnar product with a surfactant film by a surfactant coating mechanism to obtain a solid fuel with measures against odor leakage.

[0019] The invention according to claim 3 provides a solid fuel mainly composed of waste plastic and waste paper, wherein the waste plastic is melted and solidified and the outer surface is covered with a resin film, so that measures against odor leakage are taken.

[0020] The invention according to claim 4 provides a solid fuel mainly composed of waste plastic and waste paper, wherein the waste plastic is melted and solidified and the outer surface is covered with a surfactant film, so that measures against odor leakage are taken.

Effects of the Invention

[0021] In the invention according to claim 1, the resin film prevents odor leakage. Therefore, the present invention provides a solid fuel with measures against odor leakage.

[0022] In the invention according to claim 2, the surfactant film prevents odor leakage. Therefore, the present invention provides a solid fuel with measures against odor leakage. In addition, according to claim 2, the coating liquid may be at room temperature, and a high-temperature columnar object can be forcibly cooled with a room-temperature coating liquid. As a result, a solid fuel at a low temperature close to room temperature can be easily obtained. Handling of the solid fuel becomes easier at low temperatures.

[0023] In the invention according to claim 3, the solid fuel is coated with a resin film to prevent odor leakage. Therefore, the present invention provides a solid fuel that has been designed to prevent odor leakage.

[0024] In the invention according to claim 4, the solid fuel is coated with a surfactant film to prevent odor leakage. Therefore, the present invention provides a solid fuel that has been designed to prevent odor leakage. [Brief explanation of the drawing]

[0025] [Figure 1] This is a flowchart illustrating the method for producing solid fuel according to the present invention. [Figure 2] This is a basic configuration diagram of a crusher. [Figure 3] This is a side view of an extrusion molding machine. [Figure 4] This is a plan view of an extrusion molding machine with a cross-section of its main components. [Figure 5] This is a basic configuration diagram of the resin coating mechanism. [Figure 6] This is a basic diagram of the surfactant coating mechanism. [Figure 7] This is a basic configuration diagram of a solid fuel manufacturing apparatus. [Figure 8] (a) is a cross-sectional view of a columnar object, and (b) is a cross-sectional view of solid fuel. [Figure 9] This diagram illustrates an example of a modification to a solid fuel manufacturing apparatus. [Figure 10] This is a basic diagram of the ring die configuration. [Figure 11] This is a diagram illustrating the operation of a ring die. [Figure 12] This is a perspective view of conventional solid fuel. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below with reference to the attached drawings. [Examples]

[0027] [Method of manufacturing solid fuel] As shown in Figure 1, the process consists of a crushing step (SP01) in which a mixture of waste plastic 11 and waste paper 12 is crushed to a predetermined size using a crusher to obtain crushed material 27; a compression and sizing step (SP02) in which the crushed material 27 is compressed using an extrusion molding machine or ring die, melted by frictional heat, and sizing to a predetermined outer diameter and length to obtain columnar material 66; and a resin coating step (SP03) in which the outer surface of the columnar material 66 is covered with a resin film 81 or a surfactant film 82 using a resin coating mechanism or a surfactant coating mechanism to obtain solid fuel 80 in which measures have been taken to prevent odor leakage. ST01 to ST03 are step numbers.

[0028] The following provides a detailed explanation of the equipment necessary for implementing the solid fuel manufacturing method described above, namely, the crusher, extruder (or ring die), and resin coating mechanism.

[0029] [Crusher] As shown in Figure 2, the crusher 20 is a single-shaft crusher whose main components are a single rotating blade 22 extending in the front-to-back direction of the drawing, a screen 23 surrounding roughly the lower half of the rotating blade 22, a fixed blade 24 positioned opposite the rotating blade 22, and a pusher 25.

[0030] Waste plastic 11 and waste paper 12 are fed into the shredder 20. This mixture 26 is pressed against the rotating blades 22 by the pusher 25. The mixture 26 is cut (crushed) by the rotating blades 22 and the stationary blades 24. Of the crushed pieces, the larger pieces that do not pass through the screen 23 are repeatedly cut by the rotating blade 22 and the stationary blade 24 while circulating between the screen 23 and the rotating blade 22, gradually becoming smaller.

[0031] The fragments, now small enough to pass through the screen 23, fall through the screen 23. These fallen fragments become the crushed material 27. This crushed material 27 is discharged by the conveyor 28. The size of the crushed material 27 can be arbitrarily selected within the range of 8 to 80 mm. In other words, the size of the crushed material 27 can be selected by changing the screen 23 to one with a different mesh size.

[0032] [Extrusion molding machine] As shown in Figure 3, the extrusion molding machine 40 includes a base 43, a gear case 44 mounted on the base 43, an extrusion motor 45 connected to the input shaft of the gear case 44, screws 46 and 47 extending horizontally from the gear case 44 away from the extrusion motor 45, a barrel 48 surrounding these screws 46 and 47, a hopper 49 attached to the base of the barrel 48 (on the gear case 44 side), a die plate 51 positioned at the tip of the barrel 48, a cutter cover 52 positioned on the outside of the die plate 51 (on the side furthest from the gear case 44), a temperature sensor 53 for measuring the temperature of the die plate 51, a heater 54 for heating the die plate 51, a water channel 55 for cooling the die plate 51, and a temperature control unit 56.

[0033] The gear case 44 serves to cantilever support the screws 46 and 47, act as a speed reducer, distribute the output of the extrusion motor 45, and determine the rotation direction of the screws 46 and 47. It is permissible to omit the speed reduction mechanism (function) from the gear case 44 by interposing a speed reducer between the extrusion motor 45 and the gear case 44.

[0034] The temperature control unit 56 plays the role of maintaining the temperature of the die plate 51 at a set temperature artificially set by the temperature setter 57. Specifically, the temperature control unit 56 compares the temperature information obtained from the temperature sensor 53 with the set temperature, and when the temperature of the die plate 51 is lower than the set temperature, it instructs the heater controller 58 to increase the heater output. The heater controller 58 increases the power supplied to the heater 54. When the temperature information obtained from the temperature sensor 53 approaches the set temperature, the temperature control unit 56 controls the power supplied to the heater 54 to be reduced. As a result, the die plate 51 is maintained at the set temperature.

[0035] The temperature control unit 56 opens a control valve 62 in the water supply pipe 61 when the temperature of the die plate 51 is higher than the set temperature. The die plate 51 is cooled as water flows through the water channel 55. When the temperature information obtained from the temperature sensor 53 approaches the set temperature, the temperature control unit 56 closes the control valve 62. As a result, the die plate 51 is maintained at the set temperature.

[0036] As shown in Figure 4, screws 46 and 47 are rotated in the gear case 44. In principle, screw 47 is rotated in opposite directions at the same speed as screw 46, but it is also acceptable to rotate screw 47 in the same direction.

[0037] The crushed material 27 fed into the hopper (Figure 3, reference numeral 49) is kneaded by screws 46 and 47. This kneading process further mixes and breaks the material. Simultaneously, frictional heat is generated during the kneading process, causing the temperature of the kneaded material to rise.

[0038] The mixed material is strongly pressed against the die plate 51 by screws 46 and 47 and extruded from the die hole 63 of the die plate 51. The diameter of the die hole 63 is, for example, 30 to 35 mm.

[0039] A pair of cutters 64 are arranged inside the cutter cover 52, and these cutters 64 are rotated by a cutter motor 65. The cutters 64 are preferably of the so-called bamboo-shaped cutter blade type. Bamboo-shaped cutter blades have a simple structure and are inexpensive.

[0040] Furthermore, it is acceptable to rotate multiple cutters 64 (two in this embodiment) with a single cutter motor 65 via a gear or chain sprocket.

[0041] The long rod-shaped body extruded from the die hole 63 is cut by the cutter 64. Cutting yields a columnar object of a predetermined length (Figure 3, reference numeral 66).

[0042] [Resin coating mechanism] As shown in Figure 5, the resin coating mechanism 70 consists of, for example, a guide cylinder 71 for guiding a columnar object 66, a vibrating conveyor 72 that receives the columnar object 66 as it falls while being guided by the guide cylinder 71 and moves horizontally, a stirrer 74 for producing a coating liquid 73, a coating liquid spray gun 75 that sprays the coating liquid 73 onto the conveyor surface at an intermediate position on the vibrating conveyor 72, and a dryer 76 positioned on the outlet side of the vibrating conveyor 72 that sprays hot air or irradiates infrared rays onto the conveyor surface.

[0043] The number of coating liquid spray guns 75 is arbitrary, but preferably two are provided. It is also preferable to place a coating liquid spray gun 75 below the conveyor surface. By applying the coating liquid 73 to the upper half of the columnar object 66 with the upper coating liquid spray gun 75 and to the lower half of the columnar object 66 with the lower coating liquid spray gun 75, the coating liquid 73 can be applied to the columnar object 66 without any leakage.

[0044] Furthermore, a mesh conveyor is preferable for the vibrating conveyor 72. With a mesh conveyor, excess coating liquid 73 passes through the mesh and falls off the conveyor surface.

[0045] [Resin that makes up the resin coating] The coating liquid 73 sprayed from the coating liquid spray gun 75 contains resin that constitutes the resin film. The type of resin that makes up the resin film can be arbitrary, but polyvinyl alcohol is preferred. Polyvinyl alcohol is supplied to the market as white or very pale yellow particles, is a type of food additive, and is considered harmless.

[0046] [How to prepare the coating solution] The polyvinyl alcohol particles are added to cold water. While stirring this cold water with a stirrer 74, the heater 77 is heated to approximately 95°C. When the temperature exceeds 90°C, the particles disappear, and an aqueous solution of polyvinyl alcohol is obtained. This aqueous solution becomes coating solution 73.

[0047] [dye] Preferably, an appropriate amount of dye is added to the stirrer 74. The external color of the solid fuel 80 can be determined by dyes. For the dye, petroleum-derived colorants are preferable, considering that it will be burned later.

[0048] [Circulation of coating solution] By the way, the columnar object 66 contains waste plastic and waste paper. The waste plastic and waste paper are somewhat dirty. The coating liquid 73 applied to the columnar object 66 can tolerate a certain degree of dirtiness. Therefore, the coating liquid 73 does not need to be virgin liquid.

[0049] Therefore, a liquid receiving pan 78 is placed below the coating liquid spray gun 75 and beneath the conveyor surface. The coating liquid 73 received in this liquid receiving pan 78 is returned to the agitator 74 via a pump and filter. This allows for the effective use of the coating liquid 73 and saves resin material used for the resin coating.

[0050] In Figure 5, the columnar object 66 is placed at the entrance of the vibrating conveyor 72 by the guide cylinder 71. Because the vibrating conveyor 72 is vibrating, any overlapping of the columnar object 66 is corrected. The coating liquid 73 is sprayed from the coating liquid spray gun 75. The coating liquid 73 is applied to the columnar object 66. During this time, the columnar object 66 rolls due to vibration. As a result, the coating liquid 73 is applied evenly to the outer surface of the columnar object 66.

[0051] Next, the coating liquid 73 is heated in the dryer 76, the water is evaporated, and the polyvinyl alcohol remains as a resin film. After passing through the drying oven 76, the columnar material 66 is cooled by the atmosphere. Polyvinyl alcohol loses its adhesive properties at low temperatures (room temperature). At the exit of the vibrating conveyor 72, the solid fuels 80 do not stick together or clump together. Even if they were to clump together, the vibrations of the vibrating conveyor 72 would cause them to break apart.

[0052] [Surfactant coating mechanism] A surfactant coating mechanism 85 is provided, having a structure almost identical to the resin coating mechanism 70 described in Figure 5. As shown in Figure 6, the surfactant coating mechanism 85 differs from the resin coating mechanism 70 in that it introduces water and surfactant into the stirrer 74 and does not have a heater 77. Other than that, it is the same as the resin coating mechanism 70, so we will use the same reference numerals as in Figure 5 and omit a detailed explanation.

[0053] [Surfactants] Recommended surfactants include polyoxyethylene fatty acid methyl esters, alkyl ether sulfates, linear alkylbenzene sulfons, polyoxyethylene alkyl ethers, and sodium fatty acids, or a mixture of two or more of these. Note that sodium fatty acid can be substituted with soap.

[0054] Alternatively, the surfactant may be a commercially available liquid dish soap. As a liquid dish soap, Mama Lemon manufactured by Lion Hygiene Co., Ltd. can be used. Mama Lemon manufactured by Lion Hygiene Co., Ltd. is an aqueous solution containing 27% surfactants (linear alkylbenzene sulfonate and alkyl ether sulfate) and a stabilizer.

[0055] [Cooling effect by coating liquid] The coating liquid 73 in Figure 6 can be at room temperature. In contrast, the temperature of the columnar object 66 falling from the guide cylinder 71 is approximately 140°C. The columnar object 66, at approximately 140°C, is forcibly cooled with a coating liquid 73 at room temperature (approximately 25°C). As a result, a solid fuel 80 at a low temperature close to room temperature can be easily obtained.

[0056] At the exit of the vibrating conveyor 72, a worker may visually inspect the condition of the solid fuel 80. Alternatively, at the exit of the vibrating conveyor 72, a worker may collect the buckets filled with solid fuel 80 and set up empty buckets. In this case, if the solid fuel 80 is close to room temperature, the work can be carried out more smoothly. In other words, the working environment can be improved by forced cooling.

[0057] [Solid fuel manufacturing equipment] A solid fuel manufacturing apparatus can be constructed by adding an air separator to the crusher (Figure 2, reference numeral 20), extrusion molding machine (Figure 3, reference numeral 40), and resin coating mechanism (Figure 5, reference numeral 70) or surfactant coating mechanism (Figure 6, reference numeral 85) described above. In other words, as shown in Figure 7, the solid fuel manufacturing apparatus 10 is mainly composed of a crusher 20, an air separator 30 located downstream of the crusher 20, an extrusion molding machine 40 located downstream of the air separator 30, and a resin coating mechanism 70 or a surfactant coating mechanism 85 located downstream of the extrusion molding machine 40.

[0058] [Air-powered separator] In the wind separator 30, air is blown from below into the zigzag passage 31. Lighter fragments rise up the zigzag passage 31. Heavier metal fasteners 32 and buttons 33 fall and are removed. In other words, the wind separator 30 removes metal fragments and pebbles from the crushed material 27.

[0059] The crushed pieces 27 are formed into columnar objects 66 by an extrusion molding machine 40, and the columnar objects 66 are formed into solid fuel 80 by a resin coating mechanism 70 or a surfactant coating mechanism 85. The structural differences between the columnar object 66 and the solid fuel 80 will be explained based on Figures 8(a) and (b).

[0060] [Columnar object] As shown in Figure 8(a), the columnar object 66 is a cylinder with an outer diameter of 30-35 mm and a length of 50-70 mm, and is made of melted and solidified waste plastic 11 and waste paper 12.

[0061] [Solid fuel] As shown in Figure 8(b), the solid fuel 80 is a cylinder with an outer diameter of 30-35 mm and a length of 80-120 mm, and consists of waste plastic 11, waste paper 12, and a resin coating 81 that encloses the waste plastic 11 and waste paper 12 together.

[0062] Alternatively, the solid fuel 80 is a cylinder with an outer diameter of 30-35 mm and a length of 80-120 mm, and consists of waste plastic 11, waste paper 12, and a surfactant coating 82 that encloses the waste plastic 11 and waste paper 12 together. The surfactant film 82 is an aggregate of surfactant powders and does not have the same strength as the resin film 81, but it does take the form of a film.

[0063] Even if organic matter adheres to waste plastic 11 or waste paper 12 and this organic matter decomposes, the odor of decomposition is blocked by the resin film 81 or the surfactant film 82. Therefore, even if stored for a long period of time, the solid fuel 80 will not smell. In particular, the surfactant film 82 exhibits not only an odor-blocking effect but also a separation effect between the solid fuels 80.

[0064] Furthermore, as shown in Figure 8(a), the outer surface 66a of the columnar object 66 is relatively flat, but the cut surface 66b made by the cutter is not flat. The not-flat surface is a jagged surface, as if it had been cut with a dull blade. This jagged cut surface 66b is also covered with the resin coating 81 or surfactant coating 82 shown in Figure 8(b). Therefore, no odor leaks from the cut surface 66b.

[0065] Incidentally, if the combustion device is small, a smaller size of solid fuel 80 is required. A solid fuel manufacturing device capable of producing small-sized solid fuel 80 is described below.

[0066] [Solid fuel manufacturing equipment (modified example)] As shown in Figure 9, the solid fuel manufacturing apparatus 10 is a system whose main components are a crusher 20, a ring die 90 located downstream of the crusher 20, and a resin coating mechanism 70 located downstream of the ring die 90, from which the solid fuel 80 is discharged.

[0067] [Ring Die] As shown in Figure 10, the ring die 90 consists of an input duct 92 for feeding the crushed material 27 into a rotating drum-shaped die 91, rollers 93 and 94 positioned inside the die 91 and rotating together with the die 91, numerous die holes 95 opened in the die 91, cutters 96 arranged along the outer circumference of the die 91, and a casing 97. The crushed material 27, fed into the die 91 through the input duct 92, is strongly compressed by the roller 93 and enters the die hole 95. The subsequent operation will be explained using Figure 11.

[0068] In Figure 11, for convenience, the cylindrical die 91 is depicted as a flat plate. As shown in Figure 11, the previous crushed material 27 remains in the die hole 95, and new crushed material 27 is pushed into it by the roller 93. During this pushing process, frictional heat is generated by the die hole 95, and this frictional heat melts the waste plastic (Figure 1, reference numeral 11) contained in the crushed material 27, causing it to act as a binder (adhesive).

[0069] The rod-shaped object 98 protrudes from the die 91 due to being pressed by the roller 93. The protruding rod-shaped object 98 is cut by bending it with the cutter 96 to obtain a columnar object 66 of a certain outer diameter and length. The resulting columnar object 66 is a cylinder with an outer diameter of 8-10 mm and a length of 20-40 mm.

[0070] The outer surface of the columnar object 66 is covered with a resin film (Figure 8(b), reference numeral 81) or a surfactant film (Figure 8(b), reference numeral 82) by a resin coating mechanism (Figure 5, reference numeral 70) or a surfactant coating mechanism 85 (Figure 6, reference numeral 85), thereby obtaining solid fuel 80.

[0071] [Solid fuel] As shown in Figure 8(b), the solid fuel 80 produced by the solid fuel production apparatus 10 is mainly composed of waste plastic 11 and waste paper 12, and is characterized in that the waste plastic 11 is melted and solidified, and the outer surface is covered with a resin film 81 or a surfactant film 82.

[0072] Even if a putrid odor were to be generated from the waste plastic 11 or waste paper 12, this odor would be blocked by the resin film 81 or surfactant film 82 and would not leak out. If any leak occurred, it would be only a small amount.

[0073] Furthermore, the columnar object 66 shown in Figure 8(a) has a gray appearance (or a mottled gray and black appearance), and its aesthetic appearance is not good. In contrast, the solid fuel 80 shown in Figure 8(b) exhibits the color of the resin coating 81. If the resin constituting the resin coating 81 is polyvinyl alcohol, the color of the resin coating 81 will be white or very light yellow, resulting in a better appearance than gray.

[0074] Furthermore, by mixing dye into the resin coating 81 to achieve a desired color, the appearance of the resin coating 81 is further enhanced. In addition, color coding allows for the identification of the manufacturer of the solid fuel 80.

[0075] Furthermore, the resin coating mechanism 70 may be a spray type as illustrated in Figure 5, or it may be an immersion type. The important thing is that the resin film 81 can be coated onto the outer surface of the columnar object 66, and the method and structure can be changed as desired. The same applies to the surfactant coating mechanism 85.

[0076] Furthermore, while polyvinyl alcohol is preferred as the resin constituting the resin film 81, other resins (excluding polyvinyl chloride) may also be used. Silicone resins and fluororesins are recommended as other resins. If the resin film 81 is made of silicone resin or fluororesin, the peeling performance is high, the solid fuels 80 do not adhere to each other, and the handling of the solid fuels 80 becomes easier.

[0077] Furthermore, the resin coating 81 may be provided not only to prevent odor leakage, but also to improve the strength of the solid fuel 80 and prevent it from collapsing.

[0078] Furthermore, the surfactant film 82 may contain other powders or the like mixed with the surfactant; the important thing is that the surfactant is the main component (60% or more, preferably 80% or more). [Industrial applicability]

[0079] This invention is suitable for solid fuels made from waste plastics and recycled paper. [Explanation of symbols]

[0080] 10... Solid fuel manufacturing equipment, 11... Waste plastic, 12... Waste paper, 20... Crusher, 26... Mixture, 27... Crushed material, 40... Extrusion molding machine, 66... ​​Columnar material, 70... Resin coating mechanism, 80... Solid fuel, 81... Resin coating, 82... Surfactant coating, 85... Surfactant coating mechanism, 90... Ring die.

Claims

1. A crushing process in which a mixture of waste plastic and waste paper is crushed to a predetermined size using a crusher to obtain crushed material, The crushed material is compressed using an extrusion molding machine or a ring die, melted by frictional heat, and sized to a predetermined outer diameter and length to obtain a columnar material; A method for producing solid fuel, comprising a resin coating step of covering the outer surface of the columnar object with a resin film using a resin coating mechanism to obtain solid fuel in which measures against odor leakage are taken.

2. A crushing process in which a mixture of waste plastic and waste paper is crushed to a predetermined size using a crusher to obtain crushed material, The crushed material is compressed using an extrusion molding machine or a ring die, melted by frictional heat, and sized to a predetermined outer diameter and length to obtain a columnar material; A method for producing solid fuel, comprising a resin coating step, in which the outer surface of the columnar object is covered with a surfactant film by a surfactant coating mechanism to obtain solid fuel in which measures against odor leakage are taken.

3. A solid fuel characterized by being primarily composed of waste plastic and waste paper, wherein the waste plastic is melted and solidified, and the outer surface is covered with a resin film to prevent odor leakage.

4. A solid fuel characterized by its main components being waste plastic and waste paper, wherein the waste plastic is melted and solidified, and the outer surface is covered with a surfactant film to prevent odor leakage.

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