WO2024232117A1 - Waste plastic-to-oil conversion system and recovery system for aluminum - Google Patents

Abstract

Provided is a waste plastic-to-oil conversion system that can suppress coking in the pyrolysis furnace. The waste plastic-to-oil conversion system 100 is provided with a pyrolysis furnace 140 that pyrolyzes waste plastic. The pyrolysis furnace 140 has a steam introduction part for introducing superheated steam into the furnace, and the waste plastic is directly heated by the superheated steam and is thermally decomposed. This waste plastic-to-oil conversion system 100 can suppress coking in the pyrolysis furnace 140.

Description

Waste plastic oil production system and aluminum recovery system

The present invention relates to a system for converting waste plastic into oil.

An oil-recovery system in which waste plastic is thermally decomposed to produce decomposition gas, which is then cooled and recovered as decomposition oil, is in widespread use. A known thermal decomposition treatment device used in this oil-recovery system is a thermal decomposition furnace having an inner cylinder made of a material with good thermal conductivity and rotated around its axis, and an outer cylinder that covers the outer periphery of the inner cylinder through a heating space and supplies heated gas into the heating space (see, for example, Patent Document 1). The thermal decomposition treatment device described in Patent Document 1 is equipped with a material input device that is connected to one end of the inner cylinder and inputs waste plastic into the inner cylinder while being isolated from the outside air, and a large number of ceramic balls are provided inside the inner cylinder. The thermal decomposition treatment device described in Patent Document 1 is also equipped with a product discharge member that is installed to cover the other end of the inner cylinder and has multiple slits with a width smaller than the outer diameter of the ceramic balls, and discharges the thermal decomposition gas and thermal decomposition residue generated in the inner cylinder through these slits, and is provided with a discharge unit housing that surrounds the other end of the inner cylinder including the product discharge member and isolates it from the outside air. Furthermore, the pyrolysis treatment device described in Patent Document 1 is equipped with a pyrolysis gas discharge device that is provided in the discharge housing and discharges pyrolysis gas to the outside, and a residue discharge device that discharges pyrolysis residue to the outside.

The material feeding device in Patent Document 1 has a cylindrical body that serves as an outer shell member, and a screw feeder is provided inside the cylindrical body. The screw feeder is composed of two screws arranged in parallel so that they mesh with each other, and is driven to rotate by an external drive unit. One end of the material feeding device penetrates the pyrolysis furnace and protrudes into the inner cylinder. The material feeding device has a material inlet connected to a material hopper on the other end, receives a supply of waste plastic from the material hopper, and feeds it into the inner cylinder of the pyrolysis furnace.

JP 2007-332220 A

However, the pyrolysis treatment device described in Patent Document 1 has a problem in that the inner tube of the pyrolysis furnace, which is made of steel plate, is the heat input part and therefore reaches the highest temperature inside the furnace, and decomposition gases and oils tend to burn to the inner surface of the inner tube, causing coking. In Patent Document 1, although many ceramic balls are provided inside the inner tube, the effect of suppressing coking is limited, and if a large amount of coking occurs, the heat input is insufficient and the waste plastic cannot be decomposed.

The present invention was made in consideration of the above problems, and aims to provide a waste plastic oil production system that can suppress coking in the pyrolysis furnace.

In order to achieve the above object, the present invention provides
A waste plastic oil production system having a pyrolysis furnace for pyrolyzing waste plastic,
The pyrolysis furnace has a steam inlet for introducing superheated steam into the furnace,
A system for producing oil from waste plastics is provided in which the waste plastics are directly heated and pyrolyzed by the superheated steam.

In the above waste plastic oil production system,
It is preferable to have a steam side mixing device for mixing an additive for the waste plastic into the superheated steam.

In the above waste plastic oil production system,
A delivery mechanism is provided for delivering the waste plastic to the pyrolysis furnace,
It is preferable to provide a pressure pipe disposed between the delivery mechanism and the pyrolysis furnace, which controls the temperature of the waste plastic and pressure-feeds the waste plastic into the pyrolysis furnace under temperature control.

In the above waste plastic oil production system,
The pyrolysis furnace preferably has a horizontally placed cylindrical body and a spherical catalyst disposed inside the cylindrical body.

In the above waste plastic oil production system,
It is preferable to have a raw material side mixing mechanism for mixing an additive into the waste plastic delivered by the delivery mechanism.

In the above waste plastic oil production system,
The waste plastic is an aluminum-containing waste plastic,
The aluminum-containing waste plastics may be directly heated by the superheated steam, and the plastic components of the aluminum-containing waste plastics may be thermally decomposed to leave aluminum.

In the above waste plastic oil production system,
a residue flow passage connected to the pyrolysis furnace, through which the aluminum-containing residue discharged from the pyrolysis furnace flows;
A remnant receiving tank connected to the remnant flow passage,
The waste material flow passage and the waste material receiving tank may control the temperature of the waste material, and the waste material may be collected in a temperature-controlled state.

In addition, in the present invention,
An aluminum recovery system for recovering aluminum by separating waste plastic from aluminum-containing waste plastic, comprising:
A pyrolysis furnace is provided for pyrolyzing the plastic components of the aluminum-containing waste plastic,
The pyrolysis furnace has a steam inlet for introducing superheated steam into the furnace,
The aluminum-containing waste plastics are directly heated by the superheated steam, and the plastic components of the aluminum-containing waste plastics are thermally decomposed to leave aluminum, thereby providing an aluminum recovery system.

In the above aluminum recovery system,
a residue flow passage connected to the pyrolysis furnace, through which the aluminum-containing residue discharged from the pyrolysis furnace flows;
A remnant receiving tank connected to the remnant flow passage,
It is preferable that the residual material flow passage and the residual material receiving tank perform temperature control of the residual material, and collect the residual material in a temperature-controlled state.

The present invention makes it possible to suppress coking in pyrolysis furnaces.

1 is a schematic diagram of a waste plastic oil production system showing a first embodiment of the present invention. FIG. 1 is a flowchart of a method for converting waste plastic into oil. FIG. 1 is a schematic diagram of a waste plastic oil production system (aluminum recovery system) showing a second embodiment of the present invention. 1 is a flowchart of a method for converting waste plastic into oil (aluminum recovery method).

FIGS. 1 and 2 show a first embodiment of the present invention, where FIG. 1 is a schematic diagram of a waste plastic oil production system, and FIG. 2 is a flowchart of a waste plastic oil production method.

This waste plastic oil production system 100 can be suitably used to produce oil from waste plastics that contain polyvinyl chloride (PVC) and polyethylene terephthalate (PET). Specifically, in this embodiment, the waste plastics contain polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyethylene (PE).

As shown in FIG. 1, this oilification system 100 has a hopper 110 into which waste plastic is fed, a pressure feeder 120 that sends out the waste plastic fed into the hopper 110, a pressure pipe 130 that controls the temperature of the waste plastic sent out from the pressure feeder 120, a pyrolysis furnace 140 that heats and decomposes the waste plastic pressed in from the pressure 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 pyrolysis furnace, and a steam-side mixing device 180 for mixing additives into the superheated steam. In this embodiment, the waste plastic is fed from the hopper 110 in a pre-crushed state. The size of the crushed waste plastic is arbitrary, but it is preferable that the diameter is 20 mm or less. Furthermore, even if foreign objects such as metals are mixed into the waste plastic, as long as they are small enough to pass through the pressure feeder 120 and the pressure-insertion pipe 130, they will not interfere with the operation of the system. In this embodiment, foreign objects with a diameter of 5 mm or less can pass through the pressure feeder 120 and the pressure-insertion pipe 130.

The hopper 110 tapers downward and has an inlet 111 for waste plastic at the top. The hopper 110 has a mixing inlet 112 on the side for mixing additives into the waste plastic, allowing any additive to be mixed into the waste plastic before the pressure feeder 120. In this embodiment, powdered hydrated lime is used as the additive. In this embodiment, the mixing inlet 112 of the hopper 110 serves as a raw material side mixing mechanism for mixing additives into the waste plastic.

The pressure feeder 120 has a cylinder 121 that extends in the direction in which the waste plastic is discharged, an extrusion screw 122 that is disposed within the cylinder 121, and a motor 123 that drives the extrusion screw 122. The waste plastic and slaked lime supplied from the hopper 110 are mixed in the extrusion screw 122 and pressure-fed to the pressure-in pipe 130 side.

The press-in pipe 130 connects the pressure feeder 120 and the pyrolysis furnace 140, and presses the waste plastic sent from the pressure feeder 120 into the pyrolysis furnace 140. In this embodiment, the press-in pipe 130 is formed with a smaller diameter than the cylindrical body 121 of the pressure feeder 120 and the cylindrical body 141 of the pyrolysis furnace 140. Specifically, the press-in pipe 130 has a constant cross section along the longitudinal direction and is nominal 100A (outer diameter 114.3 mm) or more. An electric heater (not shown) is provided in the press-in pipe 130, and the inner surface of the press-in pipe 130 is controlled by the electric heater to a temperature at which the waste plastic does not start to pyrolyze, and the waste plastic is pressed into the pyrolysis furnace in a temperature-controlled state. In this embodiment, the electric heater is provided 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.

The pyrolysis furnace 140 has a horizontal kiln structure and includes a cylindrical body 141 and a motor (not shown) for rotating the body 141. In this embodiment, the diameter of the body 141 is about 2 m, and the inclination angle of the body 141 is set to about 1 degree. A press-in pipe 130 is connected to one end of the body 141, and a residue discharge section 142 for discharging residue generated in the body 141 and a decomposition gas delivery section 143 for sending decomposition gas generated in the body 141 to the next process device are arranged on the other end of the body 141. In this embodiment, a steam introduction section 144 for introducing superheated steam into the body 141 is arranged on the other end of the body 141. The temperature inside the body 141 is controlled by superheated steam introduced from the steam introduction section 144, and the temperature inside the body 141 is controlled to be between 400°C and 500°C. In addition, since superheated steam is supplied, the oxygen concentration inside the cylinder 141 is relatively low. In this embodiment, the oxygen concentration inside the cylinder 141 is set to 3% or less. In addition, a spiral guide 141a that protrudes radially inward is formed on the inner surface of the other end of the cylinder 141. When the cylinder 141 is rotated in a predetermined direction (forward direction), the remaining material inside the cylinder 141 is guided by the guide 141a to the remaining material discharge section 142 side. On the other hand, when the cylinder 141 is rotated in the opposite direction (reverse direction) to the predetermined direction, the remaining material inside the cylinder 141 is prevented from accumulating near the remaining material discharge section 142.

In addition, a catalyst 145 for lightening the recovered cracked oil is placed inside the cylinder 141. In this 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. The residual material discharge section 142 moves the residual material through a slit smaller than the diameter of each catalyst 145 so that each catalyst 145 is not discharged together with the residual material. The size of each catalyst 145 is arbitrary, but can be 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, but is preferably 50:1 to 20:1. The catalyst 145 only needs to contain a material having a catalytic function, and may be, for example, made of only a material having a catalytic function, or may be a material having a catalytic function impregnated into a base material. The material having a catalytic function can be selected arbitrarily, but metals such as copper can be used, for example.

The cooling device 150 cools the cracked gas and steam discharged from the pyrolysis furnace 140 to produce cracked oil and water. The piping at the outlet of the pyrolysis furnace 140 from which the cracked gas and steam are discharged has a downward slope, and the inner surface of the piping is always kept at 320°C or higher and 380°C or lower, thereby preventing adhesion or adhesion of decomposition products. The cooling temperature of the cracked gas and steam in the cooling device 150 is arbitrary, but in this embodiment it is 80°C or higher and 100°C or lower. In this embodiment, the cooling device 150 also uses cooling water supplied from the recovery device 160 to cool the cracked gas and superheated steam.

The recovery unit 160 recovers the cracked oil and water, and discharges the remaining gas. The recovery unit 160 has an oil-water separation mechanism, and is able to recover high-quality hydrocarbon oil. By rapidly cooling the off-gas from the oil-water separation mechanism, it is possible to recover even lower molecular weight light components, and it is also possible to recover naphtha components such as benzene. The rapid cooling temperature in this case is, for example, 5°C or lower. The water recovered by the recovery unit 160 is sent to the cooling unit 150 as cooling water, and is also sent to the boiler 170.

The boiler 170 heats the water supplied from the recovery device 160 to produce superheated steam, and sends the superheated steam to the pyrolysis furnace 140. In this embodiment, a steam-side mixing device 180 is provided between the recovery device 160 and the boiler 170, and an additive for waste plastic is mixed into the water supplied from the recovery device 160. In this embodiment, powdered slaked lime is used as the additive. The water to which the powdered slaked lime has been added is made into superheated steam containing powdered slaked lime in the boiler 170. In this embodiment, the superheated steam in the boiler 170 is at 600°C or higher and 700°C or lower.

The oil-recovery method in the waste plastic oil-recovery system 100 configured as above will be described with reference to the flow chart of FIG.
First, the waste plastic to be converted into oil is crushed and fed into the inlet 111 of the hopper 110 (feeding step S1). Next, slaked lime is mixed into the waste plastic through the mixing inlet 112 of the hopper 110 (mixing step S2). The amount of slaked lime added is arbitrary, but if the content of plastic materials such as polyvinyl chloride and polyethylene terephthalate that react with slaked lime is known by raw material analysis or the like, the amount of slaked lime added from the mixing inlet 112 and the steam side mixing device 180 may be adjusted so that the ratio is equimolar (1:1) with the plastic material. The waste plastic mixed with slaked lime is mixed and pressure-fed by the pressure feeder 120 (mixing step S3). In the mixing step S3, the waste plastic and slaked lime are mixed evenly.

The waste plastic mixed with the slaked lime is heated to a predetermined temperature in the press-in pipe 130 (temperature control step S4). As described above, in this embodiment, the inner surface temperature of the press-in pipe 130 is controlled to 180°C or higher and 250°C or lower, and the waste plastic is in a softened state. In this embodiment, the pressure inside the press-in pipe 130 is set to 0.5 MPa or higher and 1.0 MPa or lower. The waste plastic inside the press-in pipe 130 may be in a molten state if the inner surface temperature is controlled to 200°C or higher.

The waste plastic that has been brought to a predetermined temperature in the temperature control process S4 is pressed into the pyrolysis furnace 140 through the pressurizing pipe 130 (pressurizing process S5). This allows the waste plastic to be fed into the pyrolysis furnace 140 while ensuring a seal with the atmosphere. The supply state of the waste plastic to the pyrolysis furnace 140 is controlled by controlling the drive state of the motor 123 of the pressure feeder 120. In this embodiment, the motor 123 is operated intermittently to repeatedly press and stop the waste plastic, thereby controlling the amount of waste plastic supplied to the pyrolysis furnace 140.

The waste plastics fed into the pyrolysis furnace 140 are heated by superheated steam and pyrolyzed (pyrolysis process S6). The rotation speed of the cylinder 141 is arbitrary, but in this embodiment, it is set to 0.5 to 1.0 rotations per minute, and the residence time of the pyrolyzed waste plastics is 30 to 60 minutes. The rotation direction of the cylinder 141 during normal operation in the pyrolysis process S6 is a direction (the aforementioned reverse direction) that suppresses the retention of the residual material in the cylinder 141 near the residual material discharge section 142. Then, by periodically rotating the cylinder 141 in a direction (the aforementioned forward direction) in which the residual material is guided to the residual material discharge section 142 side, the residual material in the cylinder 141 is discharged from the residual material discharge section 142. In this embodiment, the multiple catalysts 145 arranged in the pyrolysis furnace 140 flow inside the cylinder 141 together with the waste plastics when the cylinder 141 rotates. Because each catalyst 145 is spherical, it has a large contact area with the waste plastic, maximizing the effect of each catalyst 145 in lightening the cracked gas.

In the thermal decomposition step S6, the polyvinyl chloride in the waste plastic is hydroxylated by heating in a high-temperature steam atmosphere. In this embodiment, the inside of the cylinder 141 is at normal pressure. Powdered hydrated lime, which is an alkaline material, is supplied into the cylinder 141 together with the superheated steam, and since the hydrated lime is mixed into the waste plastic in the mixing step S2, when the polyvinyl chloride is hydroxylated, the hydrochloric acid content of the polyvinyl chloride is neutralized by the hydrated lime to become solid calcium chloride.

In this embodiment, since the superheated steam contains slaked lime, the contact efficiency between the waste plastic and slaked lime is extremely high. In addition, since the waste plastic and slaked lime are mixed evenly in the kneading step S3, the hydroxylation of polyvinyl chloride can be performed accurately with the minimum amount of slaked lime added. The hydroxide generated from polyvinyl chloride is further heated to become hydrocarbon oil gas. In addition, the organic acid content of polyethylene terephthalate in the waste plastic is neutralized with slaked lime to become solid calcium benzoate, which is thermally decomposed to become benzene gas. In addition, polypropylene, polystyrene, and polyethylene in the waste plastic are thermally decomposed to become hydrocarbon oil gas.

Calcium chloride and calcium benzoate produced in the pyrolysis furnace 140 are discharged as residue from the residue discharge section 142. The hydrocarbon oil gas and benzene gas produced in the pyrolysis furnace 140 are sent as cracked gas from the cracked gas delivery section 143 to the next process device. In this embodiment, the cracked gas is sent out together with high-temperature steam. The cracked gas and high-temperature steam sent out from the pyrolysis furnace 140 are cooled in the cooling device 150 (cooling step S7) and then recovered as cracked oil and water in the recovery device 160 (recovery step S8). In this embodiment, the water recovered in the recovery device 160 is sent to the cooling device 150 and boiler 170, and is reused for cooling the cracked gas in the cooling device 150 and for thermally decomposing waste plastic in the boiler 170.

In the oilification system 100 configured as described above, the waste plastic is heated directly by the superheated steam introduced into the pyrolysis furnace 140, which dramatically improves the efficiency of heat transfer to the waste plastic compared to systems that circulate a heated fluid between the inner and outer cylinders. In addition, there are no parts in the pyrolysis furnace 140 that become locally hot, which makes it possible to suppress scorching and caulking on the inner surface of the cylinder 141.

In addition, because superheated steam is supplied to the pyrolysis furnace 140, there is no need for an elaborate airtight seal to prevent the decomposition gas from leaking into the atmosphere, as is provided in conventional systems (e.g., Patent Document 1) in which no gas is supplied from the outside and only pyrolysis gas fills the inside. In addition, in the case of conventional systems, if the decomposition gas leaks, it can cause a fire or explosion, and there have been many cases of such accidents. In contrast, in the oil production system 100 of this embodiment, the oxygen concentration in the pyrolysis furnace 140 is set relatively low, so that even if the gas inside the pyrolysis furnace 140 leaks, it will not immediately ignite. Therefore, the risk of fires and other accidents caused by pyrolysis gas can be significantly reduced.

Furthermore, according to the oilification system 100 of this embodiment, the temperature of the waste plastic is controlled independently of the pressure feeder 120 by the pressure-in pipe 130, so that the temperature of the waste plastic entering the pyrolysis furnace 140 can be accurately controlled. As a result, even if the waste plastic contains materials that vaporize at relatively low temperatures, some of the heated waste plastic will not be pyrolyzed before entering the pyrolysis furnace, and pyrolysis gas will not flow back toward the waste plastic inlet. Therefore, the waste plastic can be stably fed into the pyrolysis furnace 140, and fires and other accidents caused by the backflow of pyrolysis gas can be prevented.

Furthermore, for example, as described in Patent Document 1, when a twin-shaft screw feeder is placed at the point where waste plastic is fed into the pyrolysis furnace, a backflow prevention mechanism such as a liquid tank must be installed upstream to prevent fires, explosions, etc. due to the backflow of pyrolysis gas. In the oilification system 100 of this embodiment, molten waste plastic is continuously fed into the pyrolysis furnace 140 in a compressed state through the pressure-in pipe 130, so there is no backflow of pyrolysis gas.

In addition, for example, as described in Patent Document 1, when a twin-screw feeder is placed at the waste plastic inlet to the pyrolysis furnace, the screw wears out due to foreign matter stuck in the gaps between the screws and the narrow gaps between the screws and the cylinder, and shear friction acting on the screw, which reduces the supply capacity of waste plastic to the pyrolysis furnace. In contrast, in the oilification system 100 of this embodiment, the pressure pipe 130 placed at the inlet to the pyrolysis furnace 140 has a constant cross section and a relatively large diameter, so it is not clogged with foreign matter or subjected to localized shear friction, and the supply capacity of waste plastic to the pyrolysis furnace 140 does not generally decrease. Even if the pressure pipe 130 wears out, it is sufficient to replace the pressure pipe 130, and maintenance work such as padding is not required.

In addition, a spherical catalyst 145 is placed inside the cylindrical body 141 of the pyrolysis furnace 140, which makes it possible to lighten the quality of the cracked oil. In addition, because the catalyst 145 is spherical, it is easy to replace and replenish, making it easy to maintain.

Also, since the polyvinyl chloride in the waste plastic is combined with slaked lime and steam in the pyrolysis furnace 140, there is no need to perform dechlorination or the like before feeding it into the pyrolysis furnace 140. In contrast, in the conventional technology in which the waste plastic is heated to 300°C or higher and 350°C or lower in the first stage of the pyrolysis process, and only the vinyl chloride is selectively pyrolyzed and dechlorinated in the form of hydrogen chloride, it is necessary to provide a device and process for dechlorination separately from the device and process for pyrolysis. In addition, in this conventional technology, polyvinyl chloride is decomposed into hydrochloric acid and charcoal, which is problematic in that its use as a recycled product is limited, but this problem is solved in the oilification system 100 of this embodiment. In addition, since slaked lime is mixed into the waste plastic, polyethylene terephthalate is also neutralized, and blockage of pipes, etc. due to corrosion products caused by benzoic acid, etc. is prevented.

Furthermore, according to the oil production system 100 of this embodiment, the additives are introduced into the pyrolysis furnace 140 together with the superheated steam, so the contact efficiency between the waste plastics and the additives is extremely high, and an effective reaction between the additives and the waste plastics is achieved. In other words, unlike conventional systems in which the additives are mixed only from the raw material input side, there is no lack of additive effects. In addition, for the additives added from the raw material input side, the waste plastics and additives are mixed evenly in the kneading process S3, improving the contact efficiency between the waste plastics and the additives.

Figures 3 and 4 show a second embodiment of the present invention, where Figure 3 is a schematic diagram of a waste plastic oil production system (aluminum recovery system) and Figure 4 is a flowchart of a waste plastic oil production method (aluminum recovery method).

The waste plastic oil conversion system 200 shown in FIG. 3 can effectively separate and recover aluminum from waste plastics that contain aluminum. It is difficult to recycle aluminum components, such as packaging materials made of aluminum sheets coated with plastic resin, when they become waste, which is a major issue. There are no established devices or methods capable of continuously processing large amounts of aluminum component waste, and currently, most aluminum component waste is incinerated and then disposed of in landfills. The waste plastic oil conversion system 200 and waste plastic oil conversion method of this embodiment can solve this issue, and can also be used as an aluminum recovery system and aluminum recovery method.

As shown in FIG. 3, this waste plastic oil production system 200 is the same as the first embodiment of the waste plastic oil production system 100 with the addition of a residue flow path 210 and a residue receiving tank 220. The waste plastic oil production system 200 of this embodiment has the same configuration as the first waste plastic oil production system 100, except for the residue flow path 210 and the residue receiving tank 220, and a description of these configurations will be omitted here.

The residue flow path 210 connects the downstream lower part of the pyrolysis path 140 with the upper part of the residue receiving tank 220. It is preferable that the inner surfaces of the residue flow path 210 and the residue receiving tank 220 are always kept at 400°C or higher, and are controlled to, for example, 400°C or higher and 500°C or lower. This allows the residue to be transferred from the pyrolysis furnace 140 to the residue receiving tank 220 in a temperature-controlled state.

The method of converting waste plastics into oil in the waste plastic conversion system 200 configured as described above will be described with reference to the flowchart in Figure 4. After aluminum-containing waste plastics are injected in a compressed state from the upstream part into the pyrolysis furnace 140, the waste plastics are stirred inside the pyrolysis furnace 140 and heat conduction and thermal decomposition are carried out by direct contact with superheated steam. As shown in Figure 4, the method of converting waste plastics into oil in this embodiment is obtained by adding an aluminum recovery step S9 to steps S1 to S8 of the method of converting waste plastics into oil in the first embodiment. The method of converting waste plastics into oil in this embodiment is basically the same as the first method of converting waste plastics into oil, except for the aluminum recovery step S9.

First, aluminum-containing waste plastics are crushed and fed into the inlet 111 of the hopper 110 (feeding step S1). Next, slaked lime is mixed into the aluminum-containing waste plastics through the mixing inlet 112 of the hopper 110 (mixing step S2). The aluminum-containing waste plastics mixed with the slaked lime are mixed and pressure-fed by the pressure feeder 120 (mixing step S3). The aluminum-containing waste plastics mixed with the slaked lime are heated to a predetermined temperature in the pressure-in pipe 130 (temperature control step S4). The aluminum-containing waste plastics that have been brought to the predetermined temperature in the temperature control step S4 are pressure-injected from the pressure-in pipe 130 into the pyrolysis furnace 140 (pressing step S5).

The aluminum-containing waste plastics fed into the pyrolysis furnace 140 are heated by superheated steam to pyrolyze the plastic components (pyrolysis step S6). As described above, the temperature of the superheated steam introduced into the cylinder 141 is 600°C or higher and 700°C or lower, and the temperature inside the cylinder 141 is controlled to 400°C or higher and 500°C or lower. The temperature of the superheated steam introduced does not necessarily have to be 600°C or higher, and can be adjusted to a temperature suitable for processing the aluminum-containing waste plastics within the range of 400°C or higher and 700°C or lower. As a result of the plastic components of the aluminum-containing waste plastics being gasified by pyrolysis, solid aluminum remains in the pyrolysis furnace 140. As described above, the rotation direction of the cylinder 141 during normal operation in the pyrolysis step S6 is set to a direction (reverse direction) that suppresses the retention of residual materials in the cylinder 141 near the residual material discharge section 142. The decomposition gas generated in the pyrolysis furnace 140 is cooled in the cooling device 150 (cooling step S7) and then recovered as decomposition oil in the recovery device 160 (recovery step S8). In this embodiment, too, the same effect as in the first embodiment can be obtained for the treatment of the plastic components of aluminum-containing waste plastic.

When the pressure feeding of aluminum-containing waste plastics into the pyrolysis furnace 140 is stopped and the cylinder 141 is rotated in the forward direction, the residual material in the cylinder 141 is discharged from the residual material discharge section 142. The aluminum remaining in the pyrolysis furnace 140 is discharged as residual material from the residual material discharge section 142 together with calcium chloride and calcium benzoate. The residual material discharged from the residual material discharge section 142 is transferred to the residual material receiving tank 220 through the residual material flow path 210. The aluminum of the aluminum-containing waste plastics is recovered in the residual material receiving tank 220 (aluminum recovery process S9). In this embodiment, the residual material flow path 210 and the residual material receiving tank 220 are controlled so as not to fall below 400°C, so that the aluminum material can be recovered with high precision.

The aluminum recovery method of this embodiment allows for continuous processing of large amounts of aluminum-containing waste plastics. In addition, aluminum can be recovered in an unoxidized state, allowing it to be used as a recycled material. In addition, large amounts of carbon dioxide are not emitted, as is the case with the general aluminum material manufacturing process, and this can result in a reduction in carbon dioxide emissions.

In the second embodiment, aluminum is recovered from aluminum-containing waste plastics. However, if the waste plastics contain other metals as well as aluminum, the other metals can be recovered from the waste plastics along with the aluminum. In this case, hydrocarbon oil resources can be obtained by pyrolysis, and useful metal resources such as aluminum can be recovered.

In the above embodiments, the waste plastics to be converted into oil are shown to include polyvinyl chloride, polyethylene terephthalate, polypropylene, polystyrene, and polyethylene, but any type of plastic material contained in the waste plastics can be used. Also, although slaked lime is added to the waste plastics, an alkaline material other than slaked lime may be used, for example quicklime may be used as the alkaline material. Furthermore, if the waste plastics to be converted into oil do not include polyvinyl chloride and polyethylene terephthalate, it is not necessarily necessary to add an alkaline material.

In addition, in each of the above embodiments, additives are added from both the mixing inlet 112 on the raw material side and the mixing device 180 on the steam side, but additives may be added from either the raw material side or the steam side. The additives can be changed as desired, and in addition to alkaline materials, catalytic materials, for example, can be selected. If additives are not required, the raw material side mixing mechanism and the steam side mixing device may not be provided. Furthermore, if a catalyst is not required, the spherical catalyst inside the cylinder may not be provided.

In addition, in each of the above embodiments, the pressure feeder 120 is used as the waste plastic discharge mechanism, but other discharge mechanisms such as a rotary pump may be used. In addition, the waste plastic is supplied to the pressure feeder 120 through the hopper 110, but for example, sheet-shaped waste plastic may be supplied directly from a roll to the pressure feeder 120.

　Although the embodiments of the present invention have been described above, the invention as claimed in the claims is not limited to the embodiments described above. It should also be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention.

LIST OF SYMBOLS 100 Oil production system 110 Hopper 111 Feeding port 112 Mixing port 120 Pressure feeder 121 Cylindrical body 122 Extrusion screw 123 Motor 130 Pressing pipe 140 Pyrolysis furnace 141 Cylindrical body 141a Guide section 142 Residue discharge section 143 Cracked gas delivery section 144 Steam introduction section 145 Catalyst 150 Cooling device 160 Recovery device 170 Boiler 180 Steam side mixing device 200 Oil production system 210 Residual material flow path 220 Residual material receiving tank S1 Feeding process S2 Mixing process S3 Kneading process S4 Temperature control process S5 Pressing process S6 Pyrolysis process S7 Cooling process S8 Recovery process S9 Aluminum recovery process

Claims (9)

A waste plastic oil production system having a pyrolysis furnace for pyrolyzing waste plastic,
The pyrolysis furnace has a steam inlet for introducing superheated steam into the furnace,
A waste plastic oil production system in which the waste plastic is directly heated and pyrolyzed by the superheated steam. The waste plastic oil production system according to claim 1, further comprising a steam-side mixing device for mixing an additive for the waste plastic into the superheated steam. A delivery mechanism is provided for delivering the waste plastic to the pyrolysis furnace,
2. The waste plastic oil production system as described in claim 1, further comprising an injection pipe disposed between the discharge mechanism and the pyrolysis furnace, for controlling the temperature of the waste plastic and for injecting the waste plastic into the pyrolysis furnace under temperature control. The waste plastic oil production system according to claim 3, wherein the pyrolysis furnace has a horizontally placed cylindrical body and a spherical catalyst placed inside the body. The waste plastic oil production system according to claim 4, further comprising a raw material mixing mechanism for mixing an additive into the waste plastic discharged by the discharge mechanism. The waste plastic is an aluminum-containing waste plastic,
6. A waste plastic oil production system according to claim 1, wherein 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 to leave aluminum. a residue flow passage connected to the pyrolysis furnace, through which the aluminum-containing residue discharged from the pyrolysis furnace flows;
A remnant receiving tank connected to the remnant flow passage,
7. The waste plastic oil production system according to claim 6, wherein the waste material flow passage and the waste material receiving tank perform temperature control of the waste material, and the waste material is collected in a temperature-controlled state. An aluminum recovery system for recovering aluminum by separating waste plastic from aluminum-containing waste plastic, comprising:
A pyrolysis furnace is provided for pyrolyzing the plastic components of the aluminum-containing waste plastic,
The pyrolysis furnace has a steam inlet 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 to leave aluminum in the aluminum recovery system. a residue flow passage connected to the pyrolysis furnace, through which the aluminum-containing residue discharged from the pyrolysis furnace flows;
A remnant receiving tank connected to the remnant flow passage,
9. The aluminum recovery system according to claim 8, wherein the waste material flow passage and the waste material receiving tank perform temperature control of the waste material, and recover the waste material in a temperature-controlled state.

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