Waste plastic oiling system and aluminum recovery system

Abstract

Provided is a waste plastic oiling system capable of suppressing coking in a thermal decomposition furnace. The waste plastic oiling system (100) is provided with a thermal decomposition furnace (140) that thermally decomposes waste plastic, the thermal decomposition furnace (140) has a vapor introduction unit that introduces superheated vapor into the furnace, and the waste plastic is thermally decomposed by being directly heated by the superheated vapor. According to this system (100) for oiling waste plastics, coking in the thermal decomposition furnace (140) can be suppressed.

Description

TECHNICAL FIELD

[0001] The present application relates to an oilification system of waste plastics. BACKGROUND

[0002] An oilification system in which waste plastics are thermally decomposed to produce a decomposition gas, and the decomposition gas is recovered as a decomposition oil after cooling is becoming widespread. As a thermal decomposition treatment device used in this oilification system, a device provided with a thermal decomposition furnace having an inner cylinder formed in a cylindrical shape by a material having good thermal conductivity and rotationally driven with its axis as a center, and an outer cylinder that covers the outer periphery of the inner cylinder by a heating space in which a heating gas is supplied is known (for example, refer to Patent Literature 1). The thermal decomposition treatment device described in Patent Literature 1 is provided with a material feeding device connected to one end side of the inner cylinder, and in which waste plastics are fed into the inner cylinder in a state of being isolated from the outside air, and a large number of ceramic balls are provided in the inner cylinder. In addition, the thermal decomposition treatment device described in Patent Literature 1 is provided with a product discharge member that is provided so as to cover the other end portion of the inner cylinder, and that forms a plurality of slits having a width smaller than the outer diameter of the ceramic balls, through which the thermal decomposition gas and the thermal decomposition residue generated in the inner cylinder are discharged, and that is further provided with a discharge portion frame that surrounds the other end portion of the inner cylinder including the product discharge member and that is isolated from the outside air. Further, the thermal decomposition treatment device described in Patent Literature 1 is provided with a thermal decomposition gas discharge device that is provided to the discharge portion frame and that discharges the thermal decomposition gas to the outside, and a residue discharge device that discharges the thermal decomposition residue to the outside.

[0003] The material feeding device of Patent Literature 1 has a cylinder body that becomes a skin member, and a screw feeder is provided in the cylinder body. The screw feeder has two screws arranged in parallel in a manner of engaging with each other, and is rotationally driven by a driving device provided outside. One end side of the material feeding device penetrates the thermal decomposition furnace and protrudes to the inside of the inner cylinder. The material feeding device has a material inlet connected to a material hopper at the other end side, receives the supply of waste plastics from the material hopper, and feeds them into the inner cylinder of the thermal decomposition furnace.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2007-332220 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the thermal decomposition treatment device described in Patent Literature 1, for example, since the inner cylinder of the thermal decomposition furnace formed of a steel plate is a heat supply portion, the inside of the furnace becomes the highest temperature, and there is a problem that the decomposition gas, oil component, and the like are carbonized to easily cause coking on the inner surface of the inner cylinder. In Patent Literature 1, although a large number of ceramic balls are provided in the inner cylinder, the coking suppression effect is limited, and when coking occurs in a large amount, the waste plastic cannot be decomposed due to insufficient heat supply.

[0009] The present application has been made in view of the above problems, and an object thereof is to provide a waste plastic oilification system that can suppress coking in a thermal decomposition furnace.

[0010] Method for solving the problem

[0011] To achieve the above object, the present application provides a waste plastic oilification system including:

[0012] a thermal decomposition furnace that thermally decomposes waste plastic,

[0013] the thermal decomposition furnace has a steam introduction portion that introduces superheated steam into the furnace,

[0014] the waste plastic is directly heated by the superheated steam and thermally decomposed.

[0015] In the waste plastic oilification system,

[0016] It is preferable to have a steam-side mixing device that mixes an additive for the waste plastic into the superheated steam.

[0017] In the waste plastic oilification system,

[0018] a transport mechanism that transports the waste plastic to the thermal decomposition furnace,

[0019] It is preferable to provide a press-in pipe that is disposed between the transport mechanism and the thermal decomposition furnace, and that controls the temperature of the waste plastic, and to press the waste plastic into the thermal decomposition furnace in a state where the temperature is controlled.

[0020] In the waste plastic oilification system,

[0021] The thermal decomposition furnace preferably has a cylindrical cylinder that is placed horizontally, and a spherical catalyst that is disposed inside the cylinder.

[0022] In the waste plastic oilification system,

[0023] It is preferable to have a raw material-side mixing mechanism that mixes an additive into the waste plastic transported by the transport mechanism.

[0024] In the waste plastic oilification system,

[0025] The waste plastic is aluminum-containing waste plastic,

[0026] The aluminum-containing waste plastic is directly heated by the superheated steam, and the plastic component of the aluminum-containing waste plastic is thermally decomposed while the aluminum remains.

[0027] In the oilification system of the waste plastic, there is provided:

[0028] A residual material flow passage connected to the thermal decomposition furnace and through which the residual material of the aluminum discharged from the thermal decomposition furnace flows; and

[0029] A residual material receiving tank connected to the residual material flow passage,

[0030] The residual material flow passage and the residual material receiving tank can control the temperature of the residual material, and the residual material is recovered while the temperature is controlled.

[0031] In the present application, there is provided an aluminum recovery system,

[0032] which separates waste plastic from aluminum-containing waste plastic and recovers aluminum,

[0033] The aluminum recovery system has a thermal decomposition furnace that thermally decomposes the plastic component of the aluminum-containing waste plastic,

[0034] The thermal decomposition furnace has a steam introduction portion that introduces superheated steam into the furnace,

[0035] The aluminum-containing waste plastic is directly heated by the superheated steam, and the plastic component of the aluminum-containing waste plastic is thermally decomposed while the aluminum remains.

[0036] In the aluminum recovery system, there is provided:

[0037] A residual material flow passage connected to the thermal decomposition furnace and through which the residual material of the aluminum discharged from the thermal decomposition furnace flows,

[0038] A residual material receiving tank connected to the residual material flow passage,

[0039] The residual material flow passage and the residual material receiving tank preferably control the temperature of the residual material, and the residual material is recovered while the temperature is controlled.

[0040] Effects of the Invention

[0041] According to the present application, coking in the thermal decomposition furnace can be suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic view showing an oilification system of waste plastic according to a first embodiment of the present application.

[0043] Figure 2 is a flowchart of an oilification method of waste plastic.

[0044] Figure 3 is a schematic view showing an oilification system (aluminum recovery system) of waste plastics of the second embodiment of the present application.

[0045] Figure 4 is a flowchart of an oilification method (aluminum recovery method) of waste plastics.

[0046] Explanation of symbols

[0047] 100 oilification system

[0048] 110 hopper

[0049] 111 inlet

[0050] 112 mixing inlet

[0051] 120 pressure feeder

[0052] 121 barrel

[0053] 122 extrusion screw

[0054] 123 motor

[0055] 130 press-in pipe

[0056] 140 thermal decomposition furnace

[0057] 141 barrel

[0058] 141a guide portion

[0059] 142 residue discharge portion

[0060] 143 decomposition gas delivery portion

[0061] 144 vapor introduction portion

[0062] 145 catalyst

[0063] 150 cooling device

[0064] 160 recovery device

[0065] 170 boiler

[0066] 180 vapor-side mixing device

[0067] 200 oilification system

[0068] 210 residual material flow path

[0069] 220 residual material receiving tank

[0070] S1 inputting step

[0071] S2 mixing step

[0072] S3 kneading step

[0073] S4 temperature control step

[0074] S5 press-in step

[0075] S6 thermal decomposition step

[0076] S7 cooling step

[0077] S8 recovery step

[0078] S9 aluminum recovery step DETAILED DESCRIPTION

[0079] Figure 1 and Figure 2 shows a first embodiment of the present application, Figure 1 is a schematic view of an oilification system for waste plastics, Figure 2 is a flowchart of an oilification method for waste plastics.

[0080] The oilification system 100 for waste plastics can be suitably used for oilification of waste plastics containing polyvinyl chloride (PVC) and polyethylene terephthalate (PET). Specifically, in the present embodiment, the waste plastics contain polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyethylene (PE).

[0081] As Figure 1 shown, the oilification system 100 has a hopper 110 into which waste plastics are fed, a pressure feeder 120 that feeds the waste plastics fed into the hopper 110, a press-in pipe 130 that performs temperature control of the waste plastics fed by the pressure feeder 120, a thermal decomposition furnace 140 that performs thermal decomposition of the waste plastics pressed in from the press-in pipe 130, a cooling device 150 that cools the decomposition gas to produce decomposition oil, a recovery device 160 that recovers the decomposition oil, a boiler 170 that supplies superheated steam to the thermal decomposition furnace, and a steam-side mixing device 180 for mixing an additive into the superheated steam. In the present embodiment, the waste plastics are fed from the hopper 110 in a state of being previously crushed. The size of the crushed waste plastics is an arbitrary size, but is desirably 20 mm or less in diameter. Note that even if foreign matter such as metal is mixed into the waste plastics, as long as it is a size that can pass through the pressure feeder 120 and the press-in pipe 130, no malfunction will occur in the operation of the system. In the present embodiment, as long as the foreign matter is 5 mm or less in diameter, it can pass through the pressure feeder 120 and the press-in pipe 130.

[0082] The hopper 110 has a shape that narrows downward, and has a waste plastic feeding port 111 at the upper end. The hopper 110 has a mixing port 112 for mixing an additive into the waste plastic on the side portion, and any additive can be mixed into the waste plastic before the pressure feeder 120. In the present embodiment, slaked lime in powder form is used as the additive. In the present embodiment, the mixing port 112 of the hopper 110 becomes a raw material side mixing mechanism for mixing the additive into the waste plastic.

[0083] The pressure feeder 120 has a cylinder 121 extending in the direction of conveyance of the waste plastic, an extrusion screw 122 disposed in the cylinder 121, and a motor 123 for driving the extrusion screw 122. The waste plastic and the slaked lime supplied from the hopper 110 are mixed by the extrusion screw 122 and are pressed to the press-in pipe 130 side.

[0084] The press-in pipe 130 is connected to the pressure feeder 120 and the thermal decomposition furnace 140, and presses the waste plastic conveyed from the pressure feeder 120 into the thermal decomposition furnace 140. In the present embodiment, the press-in pipe 130 is formed so as to have a smaller diameter than the cylinder 121 of the pressure feeder 120 and the cylinder 141 of the thermal decomposition furnace 140. Specifically, the press-in pipe 130 has a constant cross section in the length direction and is provided with a nominal diameter of 100A (outer diameter 114.3 mm) or more. An electric heater (not shown in the drawing) is provided in the press-in pipe 130, and the inner surface of the press-in pipe 130 is controlled to a temperature at which the waste plastic does not start to thermally decompose by the electric heater, and the waste plastic is pressed into the thermal decomposition furnace in a temperature-controlled state. In the present embodiment, the electric heater is provided so as to cover the outer surface of the press-in pipe 130, and the inner surface temperature of the press-in pipe 130 is controlled to 180°C or more and 250°C or less.

[0085] The thermal decomposition furnace 140 is a horizontally placed kiln structure having a cylindrical cylinder 141 and a motor (not shown in the figure) that rotates the cylinder 141. In the present embodiment, the diameter of the cylinder 141 is about 2 m, and the inclination angle of the cylinder 141 is set to about 1 degree. The one end side of the cylinder 141 is connected to the press-in pipe 130, and a residual material discharge portion 142 that discharges the residual material generated inside the cylinder 141, and a decomposition gas delivery portion 143 that delivers the decomposition gas generated inside the cylinder 141 to a device of the next process are provided on the other end side of the cylinder 141. In the present embodiment, a steam introduction portion 144 that introduces superheated steam into the cylinder 141 is provided on the other end side of the cylinder 141. The temperature inside the cylinder 141 is controlled by the superheated steam introduced from the steam introduction portion 144, and the temperature inside the cylinder 141 is controlled to be 400°C or higher and 500°C or lower. In addition, the oxygen concentration inside the cylinder 141 becomes relatively low due to the supply of superheated steam. In the present embodiment, the oxygen concentration inside the cylinder 141 is set to 3% or lower. In addition, a helical guide 141a that protrudes to the inner side in the radial direction is formed on the inner surface of the other end side of the cylinder 141. If the cylinder 141 is rotated in a given direction (forward direction), the residual material inside the cylinder 141 is guided to the residual material discharge portion 142 side by the guide 141a. On the other hand, if the cylinder 141 is rotated in the opposite direction to the given direction (reverse direction), the stagnation of the residual material near the residual material discharge portion 142 inside the cylinder 141 is suppressed.

[0086] In addition, a catalyst 145 for lightening the recovered decomposition oil is provided inside the cylinder 141. In the present embodiment, the catalyst 145 is formed in a spherical shape, and a large number of catalysts 145 are placed on the inner surface of the horizontally placed cylinder 141. In order not to discharge each catalyst 145 together with the residual material, the residual material discharge portion 142 moves the residual material through a slit having a size smaller than the diameter of each catalyst 145. The size of each catalyst 145 is arbitrary, but can be set to 50 mm or more and 75 mm or less in diameter. The ratio of the diameter of the cylinder 141 to the diameter of each catalyst 145 is arbitrary, and is preferably set to 50: 1 to 20: 1. The catalyst 145 can include a material having a catalyst function, for example, can include only a material having a catalyst function, or can impregnate a material having a catalyst function in a substrate or the like. The material having a catalyst function can be arbitrarily selected, but a metal such as copper can be used.

[0087] The cooling device 150 cools the decomposition gas and the steam delivered from the thermal decomposition furnace 140 to produce decomposition oil and water. The piping of the outlet portion of the thermal decomposition furnace 140 that delivers the decomposition gas and the steam is inclined downward toward the cooling device 150. ), and the pipe inner surface is continuously maintained at 320°C or higher and 380°C or lower, whereby the attachment and adhesion of the decomposition product can be prevented. The cooling temperature of the decomposition gas and the vapor in the cooling device 150 is arbitrary, but in the present embodiment, it is 80°C or higher and 100°C or lower. In addition, in the present embodiment, the cooling device 150 cools the decomposition gas and the superheated vapor using cooling water supplied from the recovery device 160.

[0088] The recovery device 160 recovers the decomposition oil and the water, and simultaneously discharges the remaining gas. The recovery device 160 has an oil-water separation mechanism, and can recover a good-quality hydrocarbon oil. In addition, by quenching the exhaust gas from the oil-water separation mechanism, a light component of a low molecule can be further recovered, and a naphtha component such as benzene can also be recovered. The quenching temperature at this time is, for example, 5°C or lower. The water recovered by the recovery device 160 is transported to the cooling device 150 as cooling water, and is also transported to the boiler 170.

[0089] The boiler 170 heats the water supplied from the recovery device 160 to produce superheated vapor, and transports the superheated vapor to the thermal decomposition furnace 140. In the present embodiment, a vapor-side mixing device 180 is provided between the recovery device 160 and the boiler 170, and is used to mix an additive for waste plastic into the water supplied from the recovery device 160. In the present embodiment, powdered slaked lime can be used as the additive. The water to which the powdered slaked lime is added is heated in the boiler 170 to produce superheated vapor containing the powdered slaked lime. In the present embodiment, the superheated vapor in the boiler 170 is 600°C or higher and 700°C or lower.

[0090] The oilification method in the oilification system 100 for waste plastic constructed as described above will be described with reference to the flowchart of FIG. 10. Figure 2

[0091] First, the waste plastic that is the object of oilification is fed to the feed inlet 111 of the hopper 110 in a crushed state (feeding step S1). Next, the slaked lime is mixed into the waste plastic through the mixing inlet 112 of the hopper 110 (mixing step S2). The amount of the slaked lime to be added is arbitrary, but in a case where the content of the plastic material that reacts with the slaked lime, such as polyvinyl chloride and polyethylene terephthalate, can be grasped by raw material analysis or the like, the amount of the slaked lime to be added from the mixing inlet 112 and the vapor-side mixing device 180 can be adjusted so as to be in an equimolar (1:1) ratio with the plastic material. The waste plastic to which the slaked lime is mixed is pressurized and fed while being mixed by the pressure feeder 120 (mixing step S3). In the mixing step S3, the waste plastic and the slaked lime are mixed in a uniform state.

[0092] ​The waste plastic mixed with slaked lime is heated to a given temperature in the press-in tube 130 (temperature control step S4). As described above, in the present embodiment, the inner surface temperature of the press-in tube 130 is controlled to be 180°C or higher and 250°C or lower, and the waste plastic becomes a softened state. In the present embodiment, the pressure in the press-in tube 130 is set to be 0.5 MPa or higher and 1.0 MPa or lower. The waste plastic in the press-in tube 130 can sometimes become a molten state when the inner surface temperature is controlled to be 200°C or higher.

[0093] In the temperature control step S4, the waste plastic set to the given temperature is pressed from the press-in tube 130 into the thermal decomposition furnace 140 (press-in step S5). Thereby, it is possible to feed the waste plastic into the thermal decomposition furnace 140 while ensuring sealing from the atmosphere side. The control of the feeding state of the waste plastic to the thermal decomposition furnace 140 is performed by controlling the driving state of the motor 123 of the pressure feeder 120. In the present embodiment, the motor 123 is intermittently operated, and the press-in and stop of the waste plastic are repeated, whereby the feeding amount of the waste plastic to the thermal decomposition furnace 140 is controlled.

[0094] The waste plastic fed into the thermal decomposition furnace 140 is thermally decomposed by being heated by superheated steam (thermal decomposition step S6). The rotation speed of the cylinder 141 is arbitrary, but in the present embodiment, it is set to be 0.5 revolutions or higher and 1.0 revolution or lower per minute, and the residence time of the thermally decomposed waste plastic is 30 minutes or longer and 60 minutes or shorter. The rotation direction of the cylinder 141 at the time of normal operation in the thermal decomposition step S6 is set to be a direction in which the residual material in the cylinder 141 is inhibited from being retained near the residual material discharge portion 142 (the aforementioned reverse direction). However, by periodically rotating the cylinder 141 in a direction in which the residual material is guided to the residual material discharge portion 142 side (the aforementioned forward direction), the residual material in the cylinder 141 is discharged from the residual material discharge portion 142. In the present embodiment, the plurality of catalysts 145 disposed in the thermal decomposition furnace 140 flow in the cylinder 141 together with the waste plastic at the time of rotation of the cylinder 141. Since each of the catalysts 145 is spherical, the contact area with the waste plastic is large, and the lightening effect of each of the catalysts 145 on the decomposition gas can be maximized.

[0095] In the thermal decomposition step S6, the polyvinyl chloride in the waste plastic is hydroxylated by being heated in a high-temperature steam atmosphere. In the present embodiment, the inside of the cylinder 141 is at normal pressure. The powder-like slaked lime as an alkaline material is supplied into the inside of the cylinder 141 together with the superheated steam, and the slaked lime is mixed into the waste plastic in the mixing step S2, and thus, at the time of hydroxylation of the polyvinyl chloride, the hydrochloric acid component of the polyvinyl chloride is neutralized by the slaked lime to become solid calcium chloride.

[0096] In the present embodiment, the slaked lime is contained in the superheated steam, and thus the contact efficiency of the waste plastic with the slaked lime is very high. In addition, the waste plastic and the slaked lime are mixed without unevenness in the kneading step S3, and thus the hydrolysis of the polyvinyl chloride can be accurately performed with the required minimum amount of addition of the slaked lime. The hydroxide generated from the polyvinyl chloride is further heated to become a hydrocarbon oil gas. In addition, in the polyethylene terephthalate in the waste plastic, the organic acid component is neutralized by the slaked lime to become solid calcium benzoate, and is thermally decomposed to become benzene gas. In addition, the polypropylene, the polystyrene, and the polyethylene in the waste plastic are thermally decomposed to become a hydrocarbon oil gas.

[0097] The calcium chloride and the calcium benzoate generated in the thermal decomposition furnace 140 are discharged from the residue discharge portion 142 as residues. The hydrocarbon oil gas and the benzene gas generated in the thermal decomposition furnace 140 are transported from the decomposition gas transport portion 143 to the device of the next step as decomposition gases. In the present embodiment, the decomposition gases are transported together with the high-temperature steam. The decomposition gases and the high-temperature steam transported from the thermal decomposition furnace 140 are cooled by the cooling device 150 (cooling step S7), and then are recovered as decomposition oil and water by the recovery device 160 (recovery step S8). In the present embodiment, the water recovered by the recovery device 160 is transported to the cooling device 150 and the boiler 170, and is used again for the cooling of the decomposition gases in the cooling device 150 and the thermal decomposition of the waste plastic in the boiler 170.

[0098] According to the oilification system 100 constructed as described above, since the heating of the waste plastic is directly performed by the superheated steam introduced into the thermal decomposition furnace 140, the heat transfer efficiency to the waste plastic can be significantly increased compared to the case where the heating fluid is circulated between the inner cylinder and the outer cylinder. In addition, since there is no portion where the local high temperature exists in the thermal decomposition furnace 140, the scorching and the coking of the inner surface of the cylinder body 141 can be suppressed.

[0099] In addition, since the superheated steam is supplied to the thermal decomposition furnace 140, a precise airtight sealing device for preventing the decomposition gases from leaking to the atmosphere is not required as in the prior art (for example, Patent Document 1) in which the thermal decomposition furnace is provided so as to be filled with only the thermal decomposition gases inside and no gas is supplied from the outside. In the case of the prior art, in the event of a leakage of the decomposition gases, a fire / explosion accident can sometimes occur, and there are many such examples in practice. In contrast, in the case of the oilification system 100 of the present embodiment, the oxygen concentration in the thermal decomposition furnace 140 is set to a relatively low level, and even if the internal gas leaks from the thermal decomposition furnace 140, it does not immediately catch fire or the like. Thus, the risk of a fire or the like due to the decomposition gases can be significantly reduced.

[0100] Further, according to the oilification system 100 of the present embodiment, since the waste plastic is independently temperature-controlled in the press-in pipe 130 from the pressure-feed feeder 120, temperature control of the waste plastic entering the thermal decomposition furnace 140 can be accurately performed. Thus, even in the case where the waste plastic contains a material that vaporizes at a relatively low temperature, thermal decomposition does not occur before the heated waste plastic enters the thermal decomposition furnace, and thermal decomposition gas does not flow backward toward the waste plastic introduction port side. Therefore, the waste plastic can be stably introduced into the thermal decomposition furnace 140, and thus a fire or the like caused by the backward flow of the thermal decomposition gas can be prevented.

[0101] Further, as described in Patent Literature 1, for example, in the case where a twin-screw screw feeder is provided to the waste plastic introduction portion of the thermal decomposition furnace, there is a risk of a fire, explosion, or the like caused by the backward flow of the thermal decomposition gas, and thus a liquid seal tank or the like anti-backflow mechanism needs to be provided on the upstream side. In the oilification system 100 of the present embodiment, the waste plastic in a molten state is continuously introduced into the thermal decomposition furnace 140 in a pressurized state through the press-in pipe 130, and thus the backward flow of the thermal decomposition gas does not occur.

[0102] Further, as described in Patent Literature 1, for example, in the case where a twin-screw screw feeder is provided to the waste plastic introduction portion of the thermal decomposition furnace, when foreign matter clogging in the gap between the screws, the slit between the screw and the barrel, or the like, or the shear friction acting on the screw intensifies the wear of the screw, the supply capacity of the waste plastic to the thermal decomposition furnace decreases. In contrast, in the oilification system 100 of the present embodiment, since the cross section of the pressure pipe 130 provided to the introduction portion of the thermal decomposition furnace 140 is constant and is a relatively large diameter, clogging of foreign matter, local shear friction, and the like do not occur, and the supply capacity of the waste plastic to the thermal decomposition furnace 140 does not substantially decrease. Even if the pressure pipe 130 is worn or the like, the pressure pipe 130 can be replaced, and thus a maintenance operation such as build-up welding is not needed.

[0103] Further, since the catalyst 145 in the form of a ball is provided inside the cylinder 141 of the thermal decomposition furnace 140, the lightening of the decomposition oil can be sought. Further, since the catalyst 145 is in the form of a ball, exchange, replenishment, and the like are easy, and the maintenance is excellent.

[0104] Further, since the polyvinyl chloride in the waste plastic is combined with the slaked lime and water vapor in the thermal decomposition furnace 140, it is not necessary to perform dechlorination or the like before being fed into the thermal decomposition furnace 140. In contrast, in the prior art in which the waste plastic is heated to 300°C or higher and 350°C or lower at the early stage of the thermal decomposition process to selectively thermally decompose only the vinyl chloride to perform dechlorination in the form of hydrogen chloride, a device and a process for dechlorination need to be additionally provided in addition to the device and the process for thermal decomposition. Further, in the prior art, there is a problem that the polyvinyl chloride is decomposed into hydrochloric acid and carbon, and the use as a recycled product is limited, but this problem is eliminated in the oilification system 100 of the present embodiment. Further, since the slaked lime is mixed into the waste plastic, the polyethylene terephthalate is also neutralized, and thus the occlusion of the piping or the like due to the corrosion product such as benzoic acid is prevented.

[0105] Further, according to the oilification system 100 of the present embodiment, since the additive is introduced into the thermal decomposition furnace 140 together with the superheated vapor, the contact efficiency of the waste plastic with the additive is extremely high, and efficient reaction of the additive and the waste plastic is achieved. That is, as in the prior art in which the additive is mixed from the raw material feeding side, the additive and the effect cannot be sufficiently obtained. In addition to this, for the additive added from the raw material feeding side, the waste plastic and the additive are uniformly mixed in the kneading process S3, and the improvement of the contact efficiency of the waste plastic with the additive can be sought.

[0106] Figure 3 and Figure 4 A second embodiment of the present application is shown, Figure 3 is a schematic view of an oilification system (aluminum recovery system) for waste plastic, Figure 4 is a flowchart of an oilification method (aluminum recovery method) for waste plastic.

[0107] Figure 3 The oilification system 200 for waste plastic shown can appropriately separate and recover aluminum from waste plastic containing aluminum. Aluminum products such as packaging materials to which a plastic resin is applied to an aluminum foil are difficult to recover when they become waste, and this is a major problem. There are no devices, methods, or the like that can handle a large amount of waste of aluminum products continuously, and the current situation is that the waste of aluminum products is mostly landfilled after incineration treatment. The oilification system 200 for waste plastic and the oilification method for waste plastic of the present embodiment can solve this problem and can be utilized as an aluminum recovery system and an aluminum recovery method.

[0108] As Figure 3As shown, the waste plastic oiling system 200 of this embodiment adds a waste material flow path 210 and a waste material receiving tank 220 to the waste plastic oiling system 100 of the first embodiment. Except for the waste material flow path 210 and the waste material receiving tank 220, the waste plastic oiling system 200 of this embodiment has the same configuration as the first waste plastic oiling system 100, and these configurations are omitted here.

[0109] The waste material flow path 210 is connected to the lower downstream side of the pyrolysis path 140 and the upper part of the waste material receiving tank 220. The inner surfaces of both the waste material flow path 210 and the waste material receiving tank 220 are preferably set to a constant temperature of 400°C or higher, for example, controlled to be 400°C or higher and 500°C or lower. Based on this, the waste material is transferred from the pyrolysis furnace 140 to the waste material receiving tank 220 under controlled temperature conditions.

[0110] For the waste plastic oiling system 200 constructed as described above, the waste plastic oiling method is as follows: Figure 4 The flowchart illustrates this process. Starting from the upstream section, aluminum-containing waste plastic is injected into the pyrolysis furnace 140 under a compacted state. Inside the furnace 140, the mixture is stirred while undergoing heat conduction / pyrolysis through direct contact with superheated steam. (Example...) Figure 4 As shown, the waste plastic oiling method of this embodiment adds an aluminum recycling step S9 to steps S1 to S8 of the waste plastic oiling method of the first embodiment. Except for the aluminum recycling step S9, the waste plastic oiling method of this embodiment is basically the same as the waste plastic oiling method of the first embodiment.

[0111] First, aluminum-containing waste plastic, in a crushed state, is fed into the feed inlet 111 of hopper 110 (feeding step S1). Next, quicklime is mixed into the aluminum-containing waste plastic through the mixing inlet 112 of hopper 110 (mixing step S2). The aluminum-containing waste plastic mixed with quicklime is pressed and conveyed through a press feeder 120 while being kneaded (kneading step S3). The aluminum-containing waste plastic kneaded together with quicklime is heated to a predetermined temperature in the pressing pipe 130 (temperature control step S4). The aluminum-containing waste plastic, adjusted to the predetermined temperature in the temperature control step S4, is pressed from the pressing pipe 130 into the pyrolysis furnace 140 (pressing step S5).

[0112] The aluminum-containing waste plastic that is fed into the thermal decomposition furnace 140 is heated by superheated steam, and the plastic component is thermally decomposed (thermal decomposition step S6). As described above, the temperature of the superheated steam that is introduced into the cylindrical body 141 is 600°C or higher and 700°C or lower, and the temperature inside the cylindrical body 141 is controlled to be 400°C or higher and 500°C or lower. Note that the temperature of the superheated steam that is introduced does not necessarily need to be set to 600°C or higher, and can be adjusted to a temperature that is suitable for the treatment of the aluminum-containing waste plastic within a range of 400°C or higher and 700°C or lower. The plastic component of the aluminum-containing waste plastic is gasified by thermal decomposition, and as a result, solid aluminum remains inside the thermal decomposition furnace 140. As described above, the direction of rotation of the cylindrical body 141 during normal operation in the thermal decomposition step S6 is set to a direction (reverse direction) in which the stagnation of the residual material near the residual material discharge portion 142 inside the cylindrical body 141 is suppressed. The decomposition gas that is generated in the thermal decomposition furnace 140 is cooled by the cooling device 150 (cooling step S7), and is recovered as decomposition oil in the recovery device 160 (recovery step S8). Even in the present embodiment, the same advantageous effects as in the first embodiment can be obtained for the treatment of the plastic component of the aluminum-containing waste plastic.

[0113] When the press-in of the aluminum-containing waste plastic into the thermal decomposition furnace 140 is stopped and the cylindrical body 141 is rotated in the forward direction, the residual material inside the cylindrical body 141 is discharged from the residual material discharge portion 142. The aluminum that remains in the thermal decomposition furnace 140 is discharged as residual material from the residual material discharge portion 142 together with the calcium chloride and calcium benzoate. The residual material that is discharged from the residual material discharge portion 142 is transferred to the residual material receiving tank 220 through the residual material flow path 210. The aluminum of the aluminum-containing waste plastic is recovered by the residual material receiving tank 220 (aluminum recovery step S9). In the present embodiment, since the residual material flow path 210 and the residual material receiving tank 220 are controlled to be not lower than 400°C, the aluminum material can be recovered with good precision.

[0114] According to the aluminum recovery method of the present embodiment, the aluminum-containing waste plastic can be treated in large quantities and continuously. In addition, the aluminum can be recovered in a non-oxidized state, and can be effectively utilized as a recycled material. In addition, a large amount of carbon dioxide is not emitted as in the usual aluminum material manufacturing process, and a carbon dioxide reduction effect can be obtained.

[0115] Here, the method of recovering aluminum from waste plastic containing aluminum is shown in the second embodiment, but in the case where other metals are contained in the waste plastic in addition to aluminum, the other metals can be recovered from the waste plastic together with the aluminum. In this case, resources of hydrocarbon oil can be obtained by thermal decomposition, and useful metal resources such as aluminum can be recovered.

[0116] Further, in each of the above-described embodiments, as the waste plastic that is the object of oilification, waste plastics containing polyvinyl chloride, polyethylene terephthalate, polypropylene, polystyrene, and polyethylene are shown, but the present application can correspond to any type of plastic material contained in the waste plastic. In addition, although slaked lime is shown as being added to the waste plastic, an alkaline material other than slaked lime can be used, and for example, quicklime can be used as the alkaline material. Further, if polyvinyl chloride and polyethylene terephthalate are not contained in the waste plastic that is the object of oilification, it is not necessarily required to add an alkaline material.

[0117] Further, in each of the above-described embodiments, the additive is shown as being added from both the raw material side mixing inlet 112 and the vapor side mixing device 180, but the additive can be added from either the raw material side or the vapor side. In addition, the additive can be arbitrarily changed, and for example, a catalyst material can be selected in addition to an alkaline material. Further, if the additive is not required, the configuration can be such that the raw material side mixing mechanism and the vapor side mixing device are not provided. Further, if a catalyst is not required, the configuration can be such that the spherical catalyst inside the cylinder is not provided.

[0118] Further, in each of the above-described embodiments, the use of the pressure-feed feeder 120 is shown as the transport mechanism for the waste plastic, but for example, another transport mechanism such as a rotary pump can be used. In addition, the supply of the waste plastic from the hopper 110 to the pressure-feed feeder 120 is shown, but for example, the configuration can be such that the waste plastic is directly supplied to the pressure-feed feeder 120 from a roll to a sheet.

[0119] The above describes the embodiments of the present application, but the above-described embodiments do not limit the application of the scope of the claims. In addition, it should be noted that all of the combinations of the features described in the embodiments are not necessarily required methods for solving the problems of the application.

Claims

1. An oil-based system for waste plastics, comprising a pyrolysis furnace for thermally decomposing waste plastics, wherein, The pyrolysis furnace has a steam inlet section for introducing superheated steam into the furnace. The waste plastics are thermally decomposed by being directly heated by the superheated steam.

2. The waste plastic oiling system according to claim 1, comprising: A steam-side mixing device that mixes the additives used for waste plastics into the superheated steam.

3. The waste plastic oiling system according to claim 1, comprising: A conveying mechanism that feeds the waste plastic into the pyrolysis furnace. The waste plastic oiling system is equipped with a pressing pipe, which is located between the conveying mechanism and the pyrolysis furnace to control the temperature of the waste plastic and press the waste plastic into the pyrolysis furnace under controlled temperature conditions.

4. The waste plastic oiling system according to claim 3, wherein, The pyrolysis furnace has: a horizontally placed cylindrical body and a spherical catalyst disposed inside the cylindrical body.

5. The waste plastic oiling system according to claim 4, comprising: The additive is incorporated into the raw material side mixing mechanism of the waste plastic conveyed by the conveying mechanism.

6. The waste plastic oiling system according to any one of claims 1 to 5, wherein, The waste plastic is aluminum-containing waste plastic. The aluminum-containing waste plastic is directly heated by the superheated steam, and the plastic components of the aluminum-containing waste plastic are thermally decomposed, leaving aluminum residue.

7. The waste plastic oiling system according to claim 6, comprising: A waste material flow path connected to the pyrolysis furnace, through which the waste material containing the aluminum discharged from the pyrolysis furnace flows; and The waste material receiving tank connected to the waste material flow path, The waste material flow path and the waste material receiving tank control the temperature of the waste material, and recycle the waste material under the controlled temperature condition.

8. An aluminum recycling system for recovering aluminum from aluminum-containing waste plastics, the aluminum recycling system comprising: A pyrolysis furnace for thermally decomposing the plastic components of the aluminum-containing waste plastic. The pyrolysis furnace has a steam inlet section for introducing superheated steam into the furnace. The aluminum-containing waste plastic is directly heated by the superheated steam, and the plastic components of the aluminum-containing waste plastic are thermally decomposed, leaving aluminum residue.

9. The aluminum recycling system according to claim 8, comprising: A waste material flow path connected to the pyrolysis furnace, through which the waste material containing the aluminum discharged from the pyrolysis furnace flows; and The waste material receiving tank connected to the waste material flow path, The waste material flow path and the waste material receiving tank control the temperature of the waste material, and recycle the waste material under controlled temperature conditions.

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