Method for producing granulated body, apparatus for producing granulated body, and method for melting treatment of material using granulated body

Abstract

When producing a granulated body formed of waste containing plastic, this invention obtains a granulated body having a grain size smaller than that of the waste before compression by compressing the waste to produce a compressed body of the waste and crushing the compressed body. This apparatus for producing a granulated body includes: a compressed body producing device 51 for producing a compressed body of waste 3 containing plastic by compressing the waste; and a crushing device 52 for producing a granulated body having a grain size smaller than that of the waste before compression by crushing the compressed body produced by the compressed body producing device 51.

Description

Method for producing granulated particles, apparatus for producing granulated particles, and method for melting a molten material using granulated particles

[0001] The present invention relates to a method for producing granulated particles, an apparatus for producing granulated particles, and a method for melting a molten material using granulated particles.

[0002] As waste plastics, there are recycling residues discharged from the recycling processes of automobiles, electrical appliances, electric and electronic parts, buildings, and the like. As a use of such waste plastics such as recycling residues, fuel used in a melting furnace or the like can be mentioned. For use as fuel in a melting furnace or the like, it is known, for example, in JP2024-084877A to solidify waste plastics into pellets.

[0003] The technique described in JP2024-084877A uses a screw that compresses plastic waste while sending it to a discharge part inside a casing, discharges the compacted and solidified plastic waste from the discharge part, and cuts the discharged compacted plastic waste with a cutting device to make it into pellets.

[0004] However, a relatively large amount of energy is required to compact and solidify plastic waste into pellets. Moreover, a large amount of energy is also required in the process of cutting the compacted and solidified waste plastics. Also, if the waste plastics harden too much in the compaction process, there is a problem that it takes time to burn and is inefficient when used as fuel in a melting furnace or the like. Furthermore, if waste plastics with a small bulk specific gravity, such as packaging materials, are put into a melting furnace or the like without being compacted, they will scatter due to a gas flow such as combustion air and cannot be effectively utilized as fuel.

[0005] Therefore, an object of the present invention is to enable waste plastics to be made into fuel without inputting a large amount of energy and to make waste plastics into a fuel with good combustibility.

[0006] To achieve this objective, the present invention provides a method for producing granules formed from plastic-containing waste, comprising: compressing the waste to produce a compressed waste body; and crushing the compressed body to obtain granules with a lower particle size than the waste before compression.

[0007] In this method, plastic-containing waste only needs to be compressed to a degree that it can be crushed, and does not need to be compacted as it would be when pelletized by cutting, thus eliminating the need for the pressure and thermal energy required for compaction. Furthermore, after compression, the plastic-containing waste is crushed to form granules with a lower particle size than the waste before compression. These granules are not compacted, and their bulk density is increased, resulting in good combustibility.

[0008] According to the method for manufacturing granulated materials of the present invention, when manufacturing a compressed waste body, it is preferable to transport and compress the waste using a screw placed inside a casing, discharge the compressed waste body from an opening provided in the casing at a downstream position along the direction of waste transport by the screw, and when decomposing the discharged compressed waste body, decomposing it using a decomposing device provided at a space in front of the opening along the direction of waste transport by the screw.

[0009] In this manner, the plastic-containing waste is preferably compressed by the screw and preferably crushed by the crushing device.

[0010] In the method for producing granulated material of the present invention, it is preferable to use a rotary crushing arm as the crushing device.

[0011] In this way, plastic-containing waste is preferably crushed.

[0012] In the method for producing granulated material of the present invention, it is preferable that the distance between the opening and the crushing arm be 0.05 times or more and 0.2 times or less the diameter of the opening.

[0013] In this way, plastic-containing waste is crushed under favorable conditions.

[0014] The present invention provides a granular material manufacturing apparatus that includes a compression material manufacturing apparatus for producing a compressed waste material by compressing plastic-containing waste, and a crushing apparatus for producing a granular material with a lower particle size than the waste material before compression by crushing the compressed material produced by the compression material manufacturing apparatus.

[0015] According to this granulation manufacturing apparatus, plastic-containing waste only needs to be compressed to a degree that it can be crushed by the compression manufacturing apparatus. Therefore, it does not need to be compacted as in the case of pelletization by cutting, and thus does not require the pressure or thermal energy required for compaction. In addition, since the plastic-containing waste is crushed by the crushing apparatus after compression, it becomes a granule with a lower particle size than the waste before compression, and this granule is not compacted, and therefore has good combustibility.

[0016] According to the granulation manufacturing apparatus of the present invention, the compressed body manufacturing apparatus preferably comprises a casing, a screw disposed inside the casing and compressing waste while transporting it inside the casing, and an opening provided in the casing at a downstream position along the direction of waste transport by the screw for discharging the compressed waste from the casing.

[0017] According to this granulation manufacturing apparatus, plastic-containing waste is preferably compressed by the screw of the compression manufacturing apparatus.

[0018] According to the granulation apparatus of the present invention, the crushing device is preferably provided in front of the opening in the direction of waste transport by the screw, separated by a space.

[0019] According to this granulation manufacturing apparatus, plastic-containing waste is preferably crushed by a crushing device.

[0020] According to the granulation production apparatus of the present invention, it is preferable that the crushing device is a rotary crushing arm.

[0021] According to this granulation manufacturing apparatus, plastic-containing waste is preferably crushed.

[0022] In the granulation apparatus of the present invention, it is preferable that the distance between the opening and the arm is 0.05 times or more and 0.2 times or less the diameter of the opening.

[0023] This granulation manufacturing apparatus allows plastic-containing waste to be crushed under favorable conditions.

[0024] The present invention provides a method for melting a material to be melted using granules formed from plastic-containing waste as fuel, comprising: producing a compressed waste body by compressing the waste; producing granules with a lower particle size than the waste before compression by crushing the compressed body; supplying the granules with a lower particle size than the waste before compression together with the material to be melted into a melting furnace; and melting the material to be melted by burning the granules supplied to the melting furnace to bring the furnace to a predetermined melting temperature.

[0025] In this method, the plastic-containing waste only needs to be compressed to a degree that it can be crushed, and does not need to be compacted as it would be when pelletized by cutting, thus eliminating the need for the pressure and thermal energy required for compaction. Furthermore, the plastic-containing waste is crushed after compression, resulting in a granule with a lower particle size than the waste before compression. This granule is not compacted and has an increased bulk density, resulting in good combustibility. Therefore, the granule formed from the plastic-containing waste can be suitably used as fuel, and the material to be melted can be suitably melted.

[0026] According to the melting treatment method for materials to be melted of the present invention, when producing a compressed waste body, the waste is transported and compressed by a screw placed inside a casing, the compressed waste body is discharged from an opening provided in the casing at a downstream position along the direction of waste transport by the screw, and when the discharged compressed waste body is crushed, it is crushed by a crushing device provided at a space in front of the opening along the direction of waste transport by the screw, a rotary crushing arm is used as the crushing device, and it is preferable that the distance between the opening and the crushing arm be 0.05 times or more and 0.2 times or less the diameter of the opening.

[0027] In this way, plastic-containing waste is crushed under favorable conditions and used as fuel, allowing the material to be melted to be effectively treated.

[0028] According to the present invention, waste plastics can be converted into fuel without requiring a large amount of energy input, and moreover, waste plastics can be used as a fuel with good combustibility.

[0029] This figure shows a granular material manufacturing apparatus according to an embodiment of the present invention. This figure shows the configuration of the crushing arm in the crushing apparatus shown in Figure 1. This figure shows the plastic-containing waste before fuel treatment in Example 2. This figure shows the granular material obtained in Example 2. Embodiment

[0030] As shown in Figure 1, the granulation production apparatus of the embodiment of the present invention comprises a compressed body production apparatus 51 and a crushing apparatus 52.

[0031] The compressed body manufacturing apparatus 51 compresses and discharges plastic waste (an example of plastic-containing waste) 3 that has been put into the casing 2 using a horizontally positioned screw 4. In other words, the compressed body manufacturing apparatus 51 has a casing 2, an input section 7 into which the plastic waste 3 is put into the casing 2, an output section 8 that discharges the compressed plastic waste 3 from inside the casing 2, and a rotary screw 4 that compresses the plastic waste 3 that has been put into the casing 2 from the input section 7 while sending it toward the output section 8.

[0032] The discharge section 8 has a discharge port 19 provided in the casing 2 and a discharge nozzle 20 that communicates with the discharge port 19.

[0033] The screw 4 has a rotating shaft 23 that passes horizontally through the casing 2 and helical screw blades 24 provided on the outer circumference of the rotating shaft 23. The casing 25 is equipped with an electric motor 25 that rotates the rotating shaft 23. The pitch of the screw blades 24 may be constant, or it may decrease towards the discharge section 8 side, i.e., the downstream side. This is done to compress the plastic waste 3.

[0034] Although not shown in the diagram, the inner surface of the casing 2 may be provided with multiple protrusions to prevent the plastic waste 3 from rotating together with the screw 4.

[0035] The casing 2 may be configured to heat the plastic waste 3 introduced into the casing 2, for example, by providing a heater on the faceplate 18 in the portion corresponding to the downstream end of the screw 4. However, it is preferable not to use a heater because if the plastic waste 3 melts inside the compressed body manufacturing apparatus 51, the compressed body will not be crushed.

[0036] The tip portion 53 of the rotating shaft 23 penetrates the casing 2 and protrudes outward from the casing 2. The tip 54 of the rotating shaft 23 is further from the casing than the tip of the discharge nozzle 20, and the crushing device 52 is constructed by providing a crushing arm 55 at this tip 54 of the rotating shaft 23. That is, the crushing arm 55 of the crushing device 52 is provided in front of the opening 56 in the direction of waste transport by the screw 4, separated by a space. The crushing arm 55 is rotatable integrally with the rotating shaft 23 in the vertical plane.

[0037] An opening 56 is formed at the tip of the discharge nozzle 20, and when the crushing arm 55 rotates integrally with the rotating shaft 23, it passes a position that is horizontally distanced 57 from the opening 56, which has a predetermined diameter 58.

[0038] As shown in Figure 2, the crushing arms 55 are arranged evenly along the circumferential direction of the rotation axis 23. Each crushing arm 55 has its base end 59 attached to the rotation axis 23, and its tip 60 is a free end. In other words, each crushing arm 55 is arranged radially with respect to the rotation axis 23. Each crushing arm 55 is plate-shaped and, when viewed in the thickness direction, i.e., in the axial direction of the rotation axis 23, has a curved shape, for example, as shown in the figure. Note that the shape of the crushing arm 55 when viewed in the thickness direction can be a straight line or other appropriate shape instead of the above-mentioned arc shape. Each crushing arm 55 has a predetermined width and, as a result, has an inner circumferential arc 61 and an outer circumferential arc 62. As shown by arrow 63, the crushing arm 55 is configured to rotate together with the rotation axis 23 in the direction from the outer circumferential arc 62 toward the inner circumferential arc 61.

[0039] The surface 64 of the plate-shaped crushing arm 55 that faces the opening 56 of the discharge nozzle 20 is flat. However, protrusions or the like may be formed on the surface 64 of the crushing arm 55 to promote crushing when it comes into contact with the compressed waste 3 coming out of the discharge nozzle 20.

[0040] In the above, the crushing arm 55 of the crushing device 52 is shown to be driven by the rotating shaft 23 of the screw 4 of the compressed body manufacturing device 51. In other words, the crushing device 52 is shown to be driven integrally with the compressed body manufacturing device 51. However, it is also acceptable for them to be driven separately. More specifically, it is also acceptable for the crushing arm 55 of the crushing device 52 to be driven by a drive device other than the rotating shaft 23. In that case, it is possible to control the compressed body manufacturing device 51 and the crushing device 52 to operate under optimal conditions individually.

[0041] The screws 4 can also be arranged side by side, for example, in a horizontal direction. The operation of the granulation manufacturing apparatus configured as described above will be explained.

[0042] As shown in Fig. 1, with the screw 4 being rotationally driven by the electric motor 25, plastic waste 3 is introduced into the interior of the casing 2 from the inlet 10. The introduced plastic waste 3 is kneaded and compressed while being sent downstream by the rotating screw 4, thereby being densified and heated up, and discharged downstream from the opening 56 of the discharge nozzle 20 as a compressed body. That is, the plastic waste 3 is softened at the downstream end portion of the screw 4 and compressed, thereby being reduced in volume.

[0043] The compressed body of the plastic waste 3 discharged from the opening 56 of the discharge nozzle 20 hits the crushing arm 55 that rotates integrally with the screw 4, and is crushed by this crushing arm 55. As a result, the plastic waste 3 introduced into the interior of the casing 2 has an increased bulk specific gravity compared to the original waste 3 and is formed into a granular form with a low particle size.

[0044] This granular material is not in the form of hard and compacted pellets such as those obtained by the apparatus of JP2024 - 084877A, but is formed into a granular state in which the granular materials are not in close contact with each other. Moreover, plastics with a small bulk specific gravity such as packaging materials contained in the waste 3 shrink or granulate with other wastes, resulting in a granular form with a lower particle size than the original waste 3. From this, this granular material has better combustibility compared to known hard块状 pellets. Therefore, this granular material is suitably used as a fuel for a melting furnace or the like.

[0045] It is preferable to adjust the operating conditions of the compressed body manufacturing apparatus 51 and the crushing apparatus 52 so that 90 mass% of the granular material has a particle size of less than 50 mm and 100 mass% has a particle size of less than 100 mm. When miscellaneous plastics are mixed as the plastic waste 3, the granular material is usually a mixture of these multiple types of granular materials. Such a granular material has the advantage that when supplied as a fuel to a melting furnace or the like, clogging is less likely to occur in the supply path. Moreover, such a granular material can be obtained without consuming a large amount of energy in the compressed body manufacturing apparatus 51 and the crushing apparatus 52. Also, due to the increased bulk specific gravity and low particle size, a fuel in the form of a granular material with good combustibility can be obtained.

[0046] The bulk density of the granulated material is preferably 0.2 to 0.4. Granulated materials with a bulk density within this range are not in an excessive compaction state. Therefore, when supplied as fuel to a melting furnace or the like, there is an advantage that clogging is unlikely to occur in the supply path. Moreover, such granulated materials with a bulk density can be obtained without consuming a large amount of energy in the compaction body manufacturing apparatus 51 or the crushing apparatus 52. Further, since it is not in an excessive compaction state, a fuel in the form of a granulated material with good combustibility can be obtained.

[0047] In order to manufacture the granulated material in the above-described form, it is necessary to appropriately configure the compaction body manufacturing apparatus 51 and the crushing apparatus 52. In particular, the distance between the opening 56 of the discharge nozzle 20 and the crushing arm 55 is preferably adjusted to be not less than 0.05 times and not more than 0.2 times the diameter 58 of the opening 56 according to the type of plastic contained in the waste 3, that is, its composition. For example, when the diameter 58 of the opening 56 is about 100 mm, the distance 57, which is the distance between the crushing arm 55 and the opening 56, is preferably about 5 to 20 mm. Thereby, the compressed body discharged from the opening 56 of the discharge nozzle 20 is preferably crushed well by the crushing arm 55 of the crushing apparatus 52 without being sheared as a compressed body.

[0048] Further, when the diameter 58 of the discharge nozzle 20 is D and the length of the discharge nozzle 20 is L, it is preferable to appropriately set the L / D ratio according to the type of plastic, that is, its composition. In some cases, the shape of the discharge nozzle 20 can also be tapered.

[0049] The screw 4 can be installed individually inside the casing 2, or multiple screws can be installed as described above. The discharge nozzle 20 can be installed individually, or multiple nozzles can be installed at a sufficient distance from each other. In particular, when multiple screws 4 are installed, the compressed material discharged from the discharge nozzle 20 will be correspondingly larger. And in order to discharge a large compressed material, the diameter 58 of the opening 56 of the discharge nozzle 20 will also be large. For example, the diameter 58 can be set to 90 mm or more, in which case a compressed material suitable for forming granulated materials of various specific particle sizes as described above can be easily sent from the discharge nozzle 20 toward the crushing device 52.

[0050] The large diameter 58 of the discharge nozzle 20 prevents the compressed material discharged from the nozzle 20 from becoming too dense. In other words, it prevents the compressed material from becoming too hard and unsuitable for crushing by the crushing device 52. Furthermore, if the granules obtained by the crushing device 52 are too hard and compacted, their combustibility in a melting furnace or the like using them as fuel may be poor, but this can be prevented.

[0051] Furthermore, if the diameter 58 of the opening 56 of the discharge nozzle 20 is large, it is possible to prevent problems such as long objects like wires accumulating inside the compressed body manufacturing device 51. In other words, if the diameter 58 of the opening 56 of the discharge nozzle 20 is large, foreign matter contained in the plastic waste 3 can pass through the nozzle 20 and be discharged more easily, and therefore it is possible to prevent foreign matter from accumulating inside the compressed body manufacturing device 51.

[0052] When the waste 3 is compressed in the compressed material manufacturing apparatus 51, the pressure causes the waste 3 itself to heat up. At this time, the plastic in the waste 3 often includes various thermoplastics. However, if the waste 3 containing thermoplastics heats up too much, the thermoplastics melt more than expected. As a result, the excess melted thermoplastics solidify at the opening 56 of the discharge nozzle 20, preventing sufficient crushing by the crushing device 52, and resulting in granulated material that is too large in size.

[0053] To prevent such a situation from occurring, it is preferable to appropriately adjust the mass ratio of thermoplastic plastic in the waste 3 fed into the compressed body manufacturing apparatus 51.

[0054] When the plastic waste 3 contains urethane resin, it is preferable to supply moisture to the waste 3 before or after it has been fed into the compressed body manufacturing device 51. This is because urethane resin is effectively granulated when moisture is supplied. When the waste 3 contains urethane resin, large pieces of urethane resin may remain when forming a compressed body without excessively compacting the waste 3. In contrast, when moisture is supplied, the urethane resin becomes powdery when heated, and is well crushed and granulated in the crushing device 52, and its bulk density also increases. The moisture remaining after the urethane resin has been turned into powder evaporates and is dehydrated under the thermal and compression environment inside the compressed body manufacturing device 51. Therefore, the granulated material obtained by crushing does not contain much moisture and becomes a high-quality fuel with a large calorific value.

[0055] Regarding moisture content, if the waste 3 is, for example, plastic used for food packaging, and the food contained a lot of moisture, then the plastic waste 3 will often have a similarly high moisture content. However, when high-moisture-content plastics are compressed into a compressed body in the compression manufacturing apparatus 51, the moisture evaporates and dehydrates under the aforementioned thermal and compression environment. Therefore, the granules obtained by crushing do not contain much moisture and become a high-quality fuel with a large calorific value. In the melting treatment method for materials to be melted according to the present invention, granules smaller in size than the waste before compression molding are supplied to the melting furnace together with the materials to be melted, and the furnace is heated to a predetermined melting temperature by burning the granules supplied to the melting furnace. This allows the materials to be melted to be suitably treated.

[0056] Plastic waste 3, that is, waste containing plastic, does not need to be 100% plastic; it may contain non-combustible materials or other combustible components as long as it has sufficient calorific value to be used as fuel.

[0057] [Example 1] Plastic-containing waste from shredder dust of home appliances and the like was converted into fuel. This waste mainly consisted of hard plastics and urethane, with some metals also present. The detailed composition was 42% by mass of thermoplastic plastics, 51% by mass of other plastics and rubber, 3% by mass of paper, wood, and cloth, and 3% by mass of metal and rubble. The bulk density was 0.15, 80% by mass consisted of particles smaller than 100 mm, and the moisture content was 7.5% by mass.

[0058] The discharge nozzle 20 of the compressed body manufacturing apparatus 51 had a diameter D of 110 mm and a length L of 480 mm. The distance 57 from the opening 56 to the crushing arm 55 was 5 mm. The temperature of the faceplate 18 was set to 120°C.

[0059] The obtained granules had a bulk density of 0.26. 96% of the granules were smaller than 50 mm and 100% were smaller than 100 mm. The granules also had a moisture content of 5.3% and a lower heating value of 23,730 kJ / kg.

[0060] [Example 2] Industrial waste was converted into fuel. This waste contained foreign materials other than plastic. The detailed composition was 73% by mass of thermoplastics, 22% by mass of paper, wood, and cloth, and 5% by mass of metal and rubble. The breakdown of thermoplastics was 15% by mass of polyethylene, 12% by mass of polypropylene, 25% by mass of polyvinyl chloride, and 21% by mass of other resins. The bulk density was 0.051, the particle size was less than 100 mm for 67% by mass, and the moisture content was 21.7% by mass. The distance 57 from the opening 56 to the crushing arm 55 was 15 mm. Figure 3 shows the plastic-containing waste before the fuel conversion treatment.

[0061] The obtained granules had a bulk density of 0.24. The particle size distribution of the granules was 92% by mass of particles smaller than 50 mm and 100% by mass of particles smaller than 100 mm. The granules also had a moisture content of 12.1% by mass and a lower heating value of 19860 kJ / kg. Figure 4 shows the obtained granules, demonstrating that the particle size distribution is lower compared to the plastic-containing waste shown in Figure 3. The units of measurement for the measurements in Figures 3 and 4 are [×10 cm].

Claims

1. A method for manufacturing granules, wherein, in manufacturing granules formed from waste containing plastic, the waste is compressed to produce a compressed waste body, and the compressed body is crushed to obtain granules with a lower particle size than the waste before compression.

2. A method for manufacturing a granulated body according to claim 1, wherein when manufacturing a compressed waste body, the waste is transported and compressed by a screw placed inside a casing, the compressed waste body is discharged from an opening provided in the casing at a downstream position along the direction of waste transport by the screw, and when the discharged compressed waste body is crushed, it is crushed by a crushing device provided at a space in front of the opening along the direction of waste transport by the screw.

3. A method for producing granulated material according to claim 2, wherein a rotary crushing arm is used as the crushing device.

4. A method for manufacturing a granulated body according to claim 3, wherein the distance between the opening and the crushing arm is 0.05 times or more and 0.2 times or less the diameter of the opening.

5. A granular material manufacturing apparatus comprising: a compression manufacturing apparatus for producing a compressed waste material by compressing plastic-containing waste; and a crushing apparatus for producing a granular material with a lower particle size than the waste material before compression by crushing the compressed material produced by the compression manufacturing apparatus.

6. A granulation manufacturing apparatus according to claim 5, wherein the compressed body manufacturing apparatus comprises a casing, a screw disposed inside the casing and for transporting and compressing waste inside the casing, and an opening provided in the casing at a downstream position along the direction of waste transport by the screw for discharging the compressed waste from the casing.

7. The apparatus for manufacturing granulated material according to claim 5, wherein the crushing device is provided with space in front of the opening in the direction of conveying the waste by the screw.

8. The apparatus for manufacturing granulated material according to claim 7, wherein the crushing device is a rotary crushing arm.

9. A granulation apparatus according to claim 8, wherein the distance between the crushing arm and the opening is 0.05 times or more and 0.2 times or less the diameter of the opening.

10. A method for melting a material to be melted using granules formed from plastic-containing waste as fuel, comprising: compressing the waste to produce a compressed waste body; crushing the compressed body to produce granules with a lower particle size than the waste before compression; supplying the granules with a lower particle size than the waste before compression to a melting furnace together with the material to be melted; and burning the granules supplied to the melting furnace to bring the furnace to a predetermined melting temperature and melt the material to be melted.

11. A method for melting a material to be melted according to claim 10, wherein when manufacturing a compressed waste body, the waste is transported and compressed by a screw placed inside a casing, the compressed waste body is discharged from an opening provided in the casing at a downstream position along the direction of transport of the waste by the screw, and when decomposing the discharged compressed waste body, it is decomposed by a decomposing device provided at a space in front of the opening along the direction of transport of the waste by the screw, the decomposing device is a rotary decomposing arm, and the distance between the opening and the decomposing arm is 0.05 times or more and 0.2 times or less the diameter of the opening.

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