Methods for recycling waste plastics, and equipment for loading waste plastics.

Abstract

To provide a waste plastic recycling method and waste plastic charging apparatus that enable the stable charging and processing of waste plastic into the carbonization chamber of a coke oven. [Solution] This method of recycling waste plastic involves dropping waste plastic P into the carbonization chamber 12 of a coke oven 11 where coke raw material C is being carbonized, using a charging device 10 from a charging port 13 located at the top of the chamber, and then thermally decomposing the waste plastic P within the carbonization chamber 12. When dropping the waste plastic P into the carbonization chamber 12 using the charging device 10, a negative pressure state is created inside the carbonization chamber 12, and the ambient temperature is measured in the waste plastic storage section 14 of the charging device 10 or in the charging path downstream thereof.

Description

Technical Field

[0001] The present invention relates to a waste plastic recycling method for treating waste plastic in a coke oven, and a waste plastic charging apparatus for charging waste plastic into a coke oven.

Background Art

[0002] Conventionally, as disposal methods for waste plastic (discarded plastic), methods of directly landfilling the waste plastic, or crushing or incinerating the waste plastic before landfilling have been adopted. However, these disposal methods have problems such as landfill site shortages and environmental pollution caused by dioxins generated during incineration. Therefore, in recent years, various waste plastic recycling technologies have been developed and put into practical use. Among them, the method of treating (carbonizing) waste plastic in a coke oven has attracted attention as an effective recycling means, since it enables large-scale recycling of waste plastic and can convert almost 100% of the waste plastic into useful materials.

[0003] When treating waste plastic in a coke oven, in the case where waste plastic is mixed with coal and charged into the carbonization chamber of the coke oven for treatment (for example, see Patent Document 1), adding a certain amount or more of waste plastic to coal will adversely affect coke quality. Therefore, development of a technology for charging and treating waste plastic on coal (coke) during carbonization is in progress.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] When processing waste plastics by charging them onto coal during carbonization, the charging port at the top of the carbonization chamber, where high-temperature coal and gas are present, is opened, and a charging device loaded with waste plastics is placed above it to charge the waste plastics into the carbonization chamber. However, the heat inside the carbonization chamber may cause the waste plastics in the charging device to melt, which could prevent the waste plastics from being charged into the carbonization chamber, potentially leading to malfunctions such as the waste plastic charging device becoming inoperable.

[0006] The object of the present invention is to provide a waste plastic recycling method and a waste plastic charging apparatus that can stably charge and process waste plastic into the carbonization chamber of a coke oven. [Means for solving the problem]

[0007] The inventors of this invention have found that when waste plastics are dropped into the carbonization chamber of a coke oven, where coke raw materials are being carbonized, using a charging device, a larger amount of hot air flows into the charging device compared to when coke raw materials are dropped in. Specifically, they found that while coke raw materials are in powder form and are transported densely into the carbonization chamber within the transport path of the charging device, waste plastics are in relatively large clumps, creating gas passages between the waste plastics, making it easier for hot air to flow in from the carbonization chamber. Based on this finding, the inventors conducted further intensive research and found that the above problem can be solved by creating a negative pressure state in the carbonization chamber when dropping waste plastics into the carbonization chamber of a coke oven using a charging device, and by measuring the ambient temperature in the waste plastic storage section of the charging device or in the charging path downstream thereof to detect the possibility of melting of the waste plastics in the waste plastic storage section. This led to the completion of the present invention.

[0008] The present invention, conceived by the inventors, is as follows: [1] A method for recycling waste plastics, wherein waste plastics are dropped into the carbonization chamber of a coke oven, in which coke raw materials are carbonized, using a charging device from an inlet located at the top, and the waste plastics are thermally decomposed in the carbonization chamber, A method for recycling waste plastics, characterized in that, when dropping waste plastics into the carbonization chamber using the aforementioned charging device, the carbonization chamber is kept under negative pressure, and the ambient temperature is measured in the waste plastic storage section of the charging device or in the charging path downstream thereof.

[0009] [2] The waste plastic recycling method according to [1] above, characterized by measuring the ambient temperature near the point where the waste plastic falls from the waste plastic storage section.

[0010] [3] The waste plastic recycling method according to [1] above, characterized in that the waste plastic storage section of the charging device is a storage hopper equipped with a feeder, and the ambient temperature near the starting point of the waste plastic falling by the feeder is measured. [4] The waste plastic recycling method according to [3] above, characterized in that the ambient temperature above the bottom surface of the feeder is measured.

[0011] [5] A method for recycling waste plastics according to any one of [1] to [4] above, characterized in that when the measured ambient temperature exceeds a preset temperature, the loading of waste plastics is stopped and / or water is sprayed into the waste plastic storage section.

[0012] [6] A method for recycling waste plastics according to any one of [1] to [5] above, characterized in that the ambient temperature is measured by a thermocouple.

[0013] [7] The method for recycling waste plastics according to any one of [1] to [6] above, characterized in that the charging device is a charging vehicle capable of traveling on the coke oven.

[0014] [8] A charging device for dropping and charging waste plastics stored in a waste plastic storage section from a charging port located at the top of the carbonization chamber of a coke oven in which coke raw materials are carbonized, A waste plastic charging device characterized by providing a temperature measuring means for measuring ambient temperature in the waste plastic storage section or the charging path downstream thereof.

[0015] [9] The waste plastic loading device according to [8] above, characterized in that the temperature measuring means is provided near the drop point of the waste plastic storage section.

[0016]

[10] The waste plastic charging device according to [8] above, characterized in that the waste plastic storage section of the charging device is a storage hopper equipped with a feeder, and the temperature measuring means is provided near the starting point of the waste plastic falling by the feeder.

[11] The waste plastic loading device according to

[10] above, characterized in that the temperature measuring means is provided above the bottom surface of the feeder.

[0017]

[12] A waste plastic loading device according to any one of the above [8] to

[11] , characterized in that it is provided with a loading stop means for stopping the loading of waste plastic when the ambient temperature measured by the temperature measuring means becomes above a preset temperature, and / or a watering means for spraying water into the waste plastic storage section.

[0018]

[13] A waste plastic loading device according to any one of the above [8] to

[12] , characterized in that a warning means is provided for issuing a warning when the ambient temperature measured by the temperature measuring means exceeds a preset temperature.

[0019]

[14] The waste plastic loading device according to any one of the above [8] to

[13] , characterized in that the temperature measuring means is a thermocouple.

[0020]

[15] The waste plastic charging apparatus according to any one of the above [8] to

[14] , characterized in that the charging apparatus is a charging car capable of traveling on the coke oven.

Effects of the Invention

[0021] According to the waste plastic recycling method and the waste plastic charging apparatus of the present invention, waste plastic can be stably charged into the carbonization chamber of a coke oven for treatment.

Brief Description of the Drawings

[0022] [Figure 1] This is an explanatory diagram of a waste plastic recycling method according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram of a waste plastic charging apparatus according to an embodiment of the present invention. [Figure 3] This is an explanatory diagram of the gas flow in a coke oven to which the waste plastic recycling method according to an embodiment of the present invention is applied.

Modes for Carrying Out the Invention

[0023] The waste plastic recycling method of the present invention is a waste plastic recycling method in which waste plastic is dropped and charged using a charging apparatus from a charging port provided at the upper part into the carbonization chamber of a coke oven where carbonization treatment of coke raw material is performed, and the waste plastic is thermally decomposed in the carbonization chamber, characterized in that when the waste plastic is dropped and charged into the carbonization chamber using the charging apparatus, the inside of the carbonization chamber is brought into a negative pressure state, and the ambient temperature is measured at the waste plastic storage section of the charging apparatus or in the charging path downstream thereof.

[0024] Here, the method of measuring the ambient temperature is not particularly limited as long as it can detect the possibility of melting of waste plastic in the waste plastic storage section. Examples include measuring the temperature of the air in the waste plastic storage section or the charging path downstream thereof, measuring the temperature of the walls in the waste plastic storage section or the charging path downstream thereof, and measuring the temperature of the waste plastic itself in the waste plastic storage section.

[0025] According to the waste plastic recycling method of the present invention, when waste plastic is dropped into the carbonization chamber using a charging device, the carbonization chamber is kept under negative pressure, and the ambient temperature is measured in the waste plastic storage section of the charging device or in the charging path downstream thereof. This allows for the detection of the possibility of melting the waste plastic, and enables the waste plastic to be stably charged into the carbonization chamber of the coke oven for processing.

[0026] The waste plastic charging device of the present invention, which can be used in the waste plastic recycling method of the present invention described above, is a charging device that drops and charges waste plastic stored in a waste plastic storage section from an inlet provided at the top of the carbonization chamber of a coke oven in which coke raw materials are carbonized, and is equipped with a temperature measuring means for measuring the ambient temperature in the waste plastic storage section or the charging path downstream thereof.

[0027] The present invention will be described in detail below. (Coke oven) A coke oven is a facility that produces coke by alternating carbonization chambers and combustion chambers. Coke raw materials are charged into the carbonization chamber and heated by the heat of the adjacent combustion chamber to carbonize them. Gas (volatile components) generated from the coke raw materials during the carbonization process are collected by sucking them out of the carbonization chamber using a gas suction system. Coke raw materials are charged into the carbonization chamber through multiple charging ports located at the top of the carbonization chamber. Since waste plastics are also charged through these charging ports, the waste plastics fall into the carbonization chamber (see Figures 1 to 3).

[0028] (Charging device) As the charging device, a device that moves between the waste plastic receiving section and the coke oven charging inlet is preferred, for example, a charging vehicle that can travel on top of the coke oven. As for the charging vehicle, for example, an embodiment using a charging vehicle (charging car) that charges coke raw materials, that is, an embodiment using a charging vehicle that is used for both charging coke raw materials and waste plastics, or an embodiment using a dedicated vehicle for charging waste plastics that is provided separately from the charging vehicle. Alternatively, an embodiment can be used in which waste plastics are charged without using a charging vehicle, for example, by using a conveying device such as a conveyor and passing it through a waste plastic storage section provided at the downstream end.

[0029] (Waste plastic) The waste plastics charged into the carbonization chamber of the coke oven by the charging device include, for example, used and discarded plastic products and scrap plastics generated during their manufacturing process. These can be divided into general waste plastics from homes, shops, and offices, and industrial waste plastics from the manufacturing, processing, and distribution of plastic products. Examples include bottles (e.g., PET bottles and non-PET bottles), bottle caps, packaging films, packing materials (e.g., expanded polystyrene packing materials), home appliances (e.g., home appliance casings, toner containers for copiers and printers), household goods (e.g., buckets), logistics materials (e.g., pallets, containers), agricultural plastics, automobile parts, pipes, and wire insulation materials.

[0030] The waste plastic can be either thermoplastic resin or thermosetting resin. Examples of thermoplastic resins include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyester (PEs), polyethylene terephthalate (PET), polyamide (PA), polycarbonate (PC), polyvinylidene chloride (PVDC), polyolefin, acrylic resin, polyvinyl alcohol (PVAL), polyacetal, polyurethane (PUR), fluoropolymer (polytetrafluoroethylene), ABS resin, AS resin, and acrylic resin (PMMA). Examples of thermosetting resins include phenolic resin, melamine resin, urea resin, polyurethane, epoxy resin, and unsaturated polyester resin.

[0031] The shape of the waste plastic charged into the carbonization chamber is not particularly limited. Examples include molded plastics such as relatively uniform, large granular, thin plate-like, or cylindrical molded products formed by volume reduction using compression or heat, and crushed plastics obtained by crushing thick, hard waste plastics. The thickness of the waste plastic charged into the carbonization chamber (the thickness of the thinnest part) is preferably 3 mm or more. This suppresses, and even prevents, the waste plastic charged into the carbonization chamber from being sucked into the gas suction system of the coke oven, thereby suppressing problems in the coke oven.

[0032] (Charging of waste plastic into the carbonization chamber) The timing for charging waste plastics into the carbonization chamber is not particularly limited as long as it is after the coke raw material has been charged. For example, since a large amount of moisture and volatile components are released from the raw material for about an hour after the coke raw material has been charged, it is preferable to avoid charging waste plastics during this period and to do so at least one hour after the coke raw material has been charged (during the carbonization process). On the other hand, since the thermal decomposition of the charged waste plastics takes more than one hour, it is preferable to charge them at least one hour before the end of the carbonization time of the coke raw material. Specifically, assuming a carbonization time of 20 hours, it is preferable to charge the waste plastics at least 19 hours after the coke raw material has been charged. In this case, the entire amount of waste plastics may be charged at once, or it may be charged in multiple batches.

[0033] When charging waste plastics into the carbonization chamber, it is preferable to charge an amount of waste plastics such that the amount of gas generated in the carbonization chamber does not exceed the gas recovery capacity of the riser pipe of the gas suction system installed in the coke oven. In this case, the carbonization chamber is made negatively pressurized by an ejector that flushes with ammonia water at high pressure in the gas suction system of the coke oven, and the ambient temperature is measured in the waste plastic storage section of the charging device or in the charging path downstream thereof.

[0034] (Measurement of ambient temperature) The ambient temperature can be measured using a temperature measuring device such as a thermocouple, non-contact thermometer, or resistance thermometer. Examples of non-contact thermometers include radiation thermometers and thermographic cameras, while examples of resistance thermometers include resistance thermometers and thermistors. However, using a thermocouple is preferable from the viewpoint of economy and simplicity.

[0035] The ambient temperature can be measured in the waste plastic storage section of the charging device or in the charging path downstream thereof, but it is preferable to measure it near the waste plastic drop point in the waste plastic storage section. Here, the waste plastic drop point refers to, for example, the drop point (starting point) where the waste plastic begins to fall when viewed from the side. Specifically, if the waste plastic storage section of the charging device is a storage hopper equipped with a feeder, this is the point where the waste plastic at the tip of the feeder falls. Furthermore, the vicinity of the waste plastic drop point is within a virtual circular area centered on the drop point (starting point), and it is preferable that this area is within a radius of 2.0m, more preferably within a radius of 1.0m, and even more preferably within a radius of 0.5m. In particular, it is preferable to measure the ambient temperature above the drop point, for example, above the bottom surface of the feeder. This prevents contact between the temperature measuring means and the falling waste plastic.

[0036] (The behavior when the measured ambient temperature exceeds a preset temperature) If the measured ambient temperature exceeds a preset temperature, it is preferable to stop the loading of waste plastic and / or spray water into the waste plastic storage area. Here, stopping the loading of waste plastic can be done by a loading stop means provided on the loading device, and spraying water into the waste plastic storage area can be done by a water spraying means provided on the loading device. The loading device may also be provided with a warning means that issues a warning when the ambient temperature measured by the temperature measuring means exceeds a preset temperature.

[0037] The waste plastic charging device of the present invention will be described below. The waste plastic charging device of the present invention is a charging device that drops waste plastic stored in a waste plastic storage section into an inlet located at the top of the carbonization chamber of a coke oven where coke raw materials are being carbonized, and is characterized in that a temperature measuring means for measuring the ambient temperature is provided in the waste plastic storage section or the charging path downstream thereof.

[0038] The waste plastic loading device (hereinafter also simply referred to as "loading device") 10 according to one embodiment of the present invention will be described below with reference to Figures 1 and 2. As shown in Figures 1 and 2, the waste plastic charging device 10 is a device that drops waste plastic P stored in the waste plastic storage section 14 from an inlet 13 located at the top of the carbonization chamber 12 of the coke oven 11 where the coke raw material C is carbonized, and is a device (charging vehicle) that can move on top of the coke oven.

[0039] The waste plastic P is supplied to a furnace hopper 15 which is fixedly positioned at a height above the charging device 10. The furnace hopper 15 is a hopper for supplying waste plastic P to a plurality of waste plastic storage units 14 provided on the charging device 10. When supplying waste plastic P to the waste plastic storage units 14, the charging device 10 is moved to position the waste plastic storage units 14 below the furnace hopper 15.

[0040] As shown in Figure 2, the waste plastic storage section 14 of the charging device 10 is a storage hopper 17 equipped with a table feeder (feeder) 16 at its lower part. Downstream from the table feeder 16 (the charging path for waste plastics), an auxiliary hopper 18 is provided, and a sleeve 19 is provided below the auxiliary hopper 18 so as to be able to move up and down. When charging waste plastics P into the carbonization chamber 12, the sleeve 19 is lowered and its lower end is connected to the charging port 13, and the damper 20 provided at the lower part of the auxiliary hopper 18 is opened, allowing the waste plastics P stored in the storage hopper 17 of the waste plastic storage section 14 to fall from the charging port 13 into the furnace top space 21 formed on the coke raw material C in the carbonization chamber 12.

[0041] As shown in Figure 3, in the carbonization chamber 12 of the coke oven 11 where the coke raw material C is carbonized, the gas generated in the carbonization chamber 12 is recovered by a gas suction system 23 having a riser pipe 22. However, when waste plastic P is dropped into the furnace top space 21 above the coke raw material C from the charging port 13 using a charging device 10, a large amount of hot air flows into the charging device 10 (waste plastic storage section 14) compared to when the coke raw material C is dropped in. This heat in the carbonization chamber 12 may cause the waste plastic P in the charging device 10 to melt. In this case, it may become impossible to charge the waste plastic P into the carbonization chamber 12, and consequently, the waste plastic P charging device 10 may become inoperable.

[0042] Therefore, as shown in Figure 2, a thermocouple (temperature measuring means) 24 is installed in an auxiliary hopper 18 located downstream of the table feeder 16, near the starting point of the waste plastic falling from the table feeder 16 in the waste plastic storage section 14, to measure the ambient temperature. This allows the waste plastic P to be stably charged into the carbonization chamber 12 of the coke oven 11 for processing. Specifically, the thermocouple 24 is positioned in front of the table feeder 16, above its bottom surface, with the starting point being the point where the waste plastic P begins to fall, i.e., the downstream tip of the table feeder 16, to measure the ambient temperature inside the charging device 10.

[0043] The charging device 10 is equipped with a control unit (not shown) for operating the charging device 10. A thermocouple 24 is connected to this control unit, and the measured ambient temperature is input to it. When the ambient temperature measured by the thermocouple 24 exceeds a preset temperature, the control unit activates one or more of the charging stop means, water spraying means, and warning means. The preset temperature is a temperature below the ambient temperature at which the waste plastic P rapidly melts, determined in advance through experiments or other means, and is also the temperature obtained by subtracting a safety margin from that temperature. Furthermore, as the measurement temperature to be compared with the preset temperature, not only the temperature directly measured by a thermocouple, etc., but also the target temperature estimated from the heating rate of the measured temperature can be used.

[0044] Here, the loading stop means is a means for stopping the loading of waste plastic P into the carbonization chamber 12, and specifically, it is a means for turning the table feeder 16 on and off or opening and closing the damper 20. The watering means is a means for watering the waste plastic storage section 14, and specifically, it is a means equipped with a shower nozzle or the like for spraying water into the storage hopper 17 and the auxiliary hopper 18. The warning means is a means for issuing a warning, and specifically, it is a means for issuing an alarm from an alarm sound issuing means or the like, or a means for issuing a warning such as displaying a warning on the screen (monitor) of the control unit.

[0045] As described above, by using the waste plastic recycling method and waste plastic charging device, it is possible to detect the possibility of waste plastic melting, allowing waste plastic to be stably charged into the carbonization chamber of the coke oven for processing.

[0046] Although the present invention has been described above with reference to embodiments, the present invention is not limited in any way to the configurations described in the embodiments described above, and includes other embodiments and modifications that can be considered within the scope of the matters described in the claims. For example, the scope of the present invention also includes cases where some or all of the above embodiments and modifications are combined to constitute the waste plastic recycling method and waste plastic charging device of the present invention. [Industrial applicability]

[0047] This invention is industrially useful because it allows for the stable charging and processing of waste plastics into the carbonization chamber of a coke oven. [Explanation of Symbols]

[0048] 10: Waste plastic charging device, 11: Coke oven, 12: Carbonization chamber, 13: Charging port, 14: Waste plastic storage section, 15: Furnace hopper, 16: Table feeder (feeder), 17: Storage hopper, 18: Auxiliary hopper, 19: Sleeve, 20: Damper, 21: Furnace top space, 22: Rising pipe, 23: Gas suction system, 24: Thermocouple (temperature measuring means), C: Coke raw material, P: Waste plastic

Claims

1. A method for recycling waste plastics, comprising: dropping waste plastics into the carbonization chamber of a coke oven, where coke raw materials are being carbonized, using a charging device from an inlet located at the top of the chamber; and thermally decomposing the waste plastics within the carbonization chamber; A method for recycling waste plastics, characterized in that, when dropping waste plastics into the carbonization chamber using the aforementioned charging device, the carbonization chamber is kept under negative pressure, and the ambient temperature is measured in the waste plastic storage section of the charging device or in the charging path downstream thereof.

2. The waste plastic recycling method according to claim 1, characterized in that the ambient temperature near the point where the waste plastic falls from the waste plastic storage section is measured.

3. The waste plastic recycling method according to claim 1, characterized in that the waste plastic storage section of the charging device is a storage hopper equipped with a feeder, and the ambient temperature near the starting point of the waste plastic falling by the feeder is measured.

4. The waste plastic recycling method according to claim 3, characterized in that the ambient temperature above the bottom surface of the feeder is measured.

5. The waste plastic recycling method according to claim 1, characterized in that when the measured ambient temperature exceeds a preset temperature, the loading of waste plastic is stopped and / or water is sprayed into the waste plastic storage section.

6. The waste plastic recycling method according to claim 1, characterized in that the ambient temperature is measured using a thermocouple.

7. The method for recycling waste plastics according to any one of claims 1 to 6, characterized in that the charging device is a charging vehicle capable of traveling on the coke oven.

8. A charging device for dropping and charging waste plastics stored in a waste plastic storage section from an inlet located at the top of the carbonization chamber of a coke oven where coke raw materials are carbonized, A waste plastic charging device characterized by providing a temperature measuring means for measuring ambient temperature in the waste plastic storage section or the charging path downstream thereof.

9. The waste plastic loading device according to claim 8, characterized in that the temperature measuring means is provided near the waste plastic drop starting point of the waste plastic storage section.

10. The waste plastic charging device according to claim 8, characterized in that the waste plastic storage section of the charging device is a storage hopper equipped with a feeder, and the temperature measuring means is provided near the starting point of the waste plastic falling by the feeder.

11. The waste plastic loading device according to claim 10, characterized in that the temperature measuring means is provided above the bottom surface of the feeder.

12. The waste plastic charging device according to claim 8, further characterized in that it is provided with a charging stop means for stopping the charging of waste plastic when the ambient temperature measured by the temperature measuring means exceeds a preset temperature, and / or a watering means for spraying water into the waste plastic storage section.

13. The waste plastic loading device according to claim 8, characterized in that a warning means is provided for issuing a warning when the ambient temperature measured by the temperature measuring means exceeds a preset temperature.

14. The waste plastic loading device according to claim 8, characterized in that the temperature measuring means is a thermocouple.

15. A waste plastic charging device according to any one of 8 to 14, characterized in that it is a charging vehicle capable of traveling on the coke oven.

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