Waste plastic oil conversion device

Abstract

To provide a waste plastic liquefaction device that can prevent pipe blockages, reduce downtime due to maintenance, and increase operational efficiency. [Solution] The waste plastic oil conversion apparatus 1 includes an extruder 11 that feeds waste plastic P0 while melting it, a primary pyrolysis tank 10 that thermally decomposes the molten plastic P1 to generate pyrolysis gas G0, a secondary pyrolysis tank 12 that separates the pyrolysis gas G0 into a low-boiling point decomposition gas G1 and a high-boiling point liquefied component K0, and reheats the liquefied component K0 to generate decomposition gas G1, a condenser 13 that condenses the decomposition gas G1, and an oil storage tank 14 that stores the liquefied component K1 condensed in the condenser 13. By preventing clogging of the piping 47 downstream of the secondary pyrolysis tank 12, the waste plastic oil conversion apparatus 1 can reduce downtime due to maintenance and increase the operating rate.

Description

Technical Field

[0001] The present invention relates to a waste plastic oil conversion device.

Background Art

[0002] In recent years, the treatment of waste plastics such as plastic products discarded after use and plastic residues generated in the manufacturing process of plastic products has become a common problem worldwide. As methods for treating waste plastics, methods such as volume reduction by incineration or pyrolysis and then disposal have been mainstream. However, from the perspective of effective utilization of resources, a waste plastic oil conversion device that recovers pyrolysis gas by pyrolyzing waste plastics and reuses the liquefied component (produced oil) obtained by condensing this pyrolysis gas has attracted attention. Generally, plastics that can be oil-converted (also called oil-conversion reduction) are thermoplastic plastics such as polystyrene, polypropylene, polycarbonate, and polyethylene.

[0003] The pyrolysis gas obtained by pyrolyzing waste plastics is a hydrocarbon gas and contains high-boiling components to low-boiling components. These high-boiling components become components with high viscosity when liquefied, and there is a risk of adhering as sludge (also called sediment) to the inside of pipes from the pyrolysis tank to the condenser tank, filters, etc., causing blockage.

[0004] Patent Document 1 discloses a waste plastic oil conversion device having a pyrolysis tank (reaction kettle) and a cooler that cools and liquefies the pyrolysis gas generated in the pyrolysis tank. This cooler has a body through which the pyrolysis gas flows and cooling heat transfer pipes disposed inside the body, and cools the pyrolysis gas flowing inside the body by flowing cooling water inside the cooling heat transfer pipes. In this waste plastic oil conversion device, a mixed liquid of low molecular weight hydrocarbons obtained by cooling, a condensate containing substances that become solid by cooling, and the downward flow liquid of the liquid film (which becomes pyrolysis oil) flowing along the outer surface of the cooling heat transfer pipes enters a solid separation tank, and the clarified liquid of the mixed liquid is recovered as produced oil.

[0005] Furthermore, Patent Document 2 discloses a waste plastic liquefaction apparatus having a pyrolysis tank (pyrolysis vessel) and a reflux tower for refluxing the pyrolysis gas produced in the pyrolysis tank. This reflux tower separates the high-boiling-point components of the pyrolysis gas and returns them to the pyrolysis tank for further pyrolysis. This waste plastic liquefaction apparatus aims to prevent the high-boiling-point components from adhering to the equipment and piping after the pyrolysis tank, thereby preventing clogging of the pipes and other components. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-216364 [Patent Document 2] Japanese Patent Publication No. 2016-60799 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the waste plastic oil conversion apparatus described in Patent Document 1, a mixture of low molecular weight hydrocarbons, condensate, and liquid film is flowed into a solid-liquid separation tank. In the solid separation tank, the solids settle by gravity due to the difference in specific gravity, and some of the solids suspended in the liquid are filtered out. The clarified liquid after solid removal is recovered as usable oil. However, because some of the solids suspended in the liquid are filtered out, the filter will eventually become clogged and must be replaced, which reduces the operating rate of the waste plastic oil conversion apparatus.

[0008] Furthermore, the waste plastic oil conversion apparatus described in Patent Document 2 separates the pyrolysis gas into low-boiling point components and high-boiling point components in a reflux tower, and recovers the low-boiling point components by condensing them as usable oil. Although the pyrolysis gas is refluxed in the reflux tower, temperature differences occur depending on the height of the reflux tower, so high-boiling point components may be mixed with the low-boiling point components. This could eventually clog the piping after the reflux tower. Clogged piping reduces the operating rate of the waste plastic oil conversion apparatus.

[0009] Therefore, the present invention was made to solve these problems and aims to provide a waste plastic oil conversion apparatus that can prevent pipe clogging caused by some of the high-boiling-point components contained in the pyrolysis gas adhering to the inner surface of the pipes as residue, thereby reducing downtime due to maintenance. [Means for solving the problem]

[0010] [1] The waste plastic oil conversion apparatus of the present invention is characterized by comprising: an extruder that feeds waste plastic as a raw material while melting it; a primary pyrolysis tank that thermally decomposes the molten waste plastic to generate pyrolysis gas; a secondary pyrolysis tank that cools the pyrolysis gas to separate it into a low-boiling point decomposition gas and a high-boiling point liquefied component, and heats the liquefied component to generate the low-boiling point decomposition gas; a condenser that collects and condenses the low-boiling point decomposition gas; an oil storage tank that stores the generated oil condensed in the condenser; piping connecting the secondary pyrolysis tank and the condenser, and piping connecting the condenser and the oil storage tank.

[0011] [2] In the waste plastic oil conversion apparatus of the present invention, the secondary pyrolysis tank has a horizontally arranged cylindrical body, a removable lid member provided at at least one opening at the horizontal end of the cylindrical body, and a heater arranged around the cylindrical body, wherein an introduction pipe for introducing the pyrolysis gas from the primary pyrolysis tank to the secondary pyrolysis tank and piping connecting the secondary pyrolysis tank and the condensation tank are detachably connected to the upper part of the cylindrical body by pipe fittings, and a discharge pipe for discharging the liquefied components accumulated inside the cylindrical body to the outside is preferably connected.

[0012] [3] In the waste plastic oil conversion apparatus of the present invention, it is preferable that the cylindrical body is provided with an overflow weir on the upstream side of the discharge pipe that causes the liquefied components accumulated inside the cylindrical body to overflow.

[0013] [4] In the waste plastic oil conversion apparatus of the present invention, the secondary pyrolysis tank further comprises a first partition wall that divides the inside of the cylindrical body into a region connected to the introduction pipe and a region connected to the piping, and has small holes through which gas can pass, and a second partition wall 33 located below the first partition wall that divides the inside of the cylindrical body vertically and has small holes through which gas and liquid can pass, and it is preferable that a catalyst is arranged in at least one of the first partition wall or the bottom of the cylindrical body.

[0014] [5] In the waste plastic oil conversion apparatus of the present invention, it is preferable that the apparatus further comprises a water seal for introducing the decomposition gas that was not liquefied in the condensing tank, and an exhaust gas decomposition apparatus connected to the water seal for discharging the decomposition gas introduced into the water seal to the outside.

[0015] [6] In the waste plastic oil conversion apparatus of the present invention, it is preferable to further include a second condenser into which the decomposition gas that was not liquefied in the condenser is introduced and condensed at a lower temperature than the condenser, and a third condenser into which the decomposition gas that was not liquefied in the second condenser is introduced and condensed at a lower temperature than the second condenser. [Effects of the Invention]

[0016] The waste plastic oilification device of the present invention cools the pyrolysis gas generated by heat-decomposing the waste plastic in the primary pyrolysis tank, and once separates it into low-boiling pyrolysis gas and high-boiling liquefied components in the secondary pyrolysis tank. At this time, the high-boiling liquefied components are temporarily retained in the secondary pyrolysis tank, and by reheating the liquefied components, the generation of low-boiling pyrolysis gas is promoted. The high-boiling liquefied components remaining in the secondary pyrolysis tank without being gasified are recovered. By adopting such a configuration, it becomes possible to condense the low-boiling pyrolysis gas and recover the produced oil such as light oil and kerosene, prevent the high-boiling liquefied components from adhering to the inner surface of the pipe as slag and clogging the pipe, reduce the downtime for maintenance, and increase the operating rate of the waste plastic oilification device.

Brief Description of the Drawings

[0017] [Figure 1] It is a configuration explanatory drawing showing the main configuration of the oilification device 1. <{ [Figure 2] It is a cross-sectional view showing the configuration of the secondary pyrolysis tank 12 according to the first example. [Figure 3] It is a cross-sectional view showing the configuration of the secondary pyrolysis tank 12A according to the second example. [Figure 4] It is a configuration explanatory drawing showing a simplified configuration of the oilification device 2 according to Application Example 1.

Modes for Carrying Out the Invention

[0018] Hereinafter, the waste plastic oilification device 1 according to the embodiment of the present invention will be described with reference to the drawings. In the following description, the waste plastic oilification device 1 may be briefly described as the oilification device 1. The waste plastic P0 to be oilified in the waste plastic oilification device 1 is plastic products discarded after use, plastic residues generated in the manufacturing process of plastic products, etc. For example, it is thermoplastic plastics such as polystyrene, polypropylene, polyethylene, styrofoam (expanded polystyrene), polyethylene terephthalate (PET), and vinyl chloride.

[0019] FIG. 1 is a configuration explanatory diagram showing the main components of the oil conversion device 1. The oil conversion device 1 includes an extruder 11 that feeds the waste plastic P0, which is a raw material, into the primary pyrolysis tank 10 while heating and melting it, and a secondary pyrolysis tank 12 that heats and decomposes the molten plastic P1 melted in the primary pyrolysis tank 10 and cools the generated pyrolysis gas G0 at a predetermined temperature to separate it into a low-boiling decomposition gas G1 and a liquefied component K0 with a higher boiling point than the decomposition gas G1. The oil conversion device 1 has, on the downstream side of the secondary pyrolysis tank 12, a condensation tank 13 that collects the decomposition gas G1 and condenses it into a liquefied component K1 of a predetermined oil component, an oil storage tank 14 that stores the liquefied component K1 obtained in the condensation tank 13, and a water seal 15 that introduces the decomposition gas G2 that was not liquefied in the condensation tank 13 and the decomposition gas G3 containing the gas that may be generated in the oil storage tank 14. The liquefied component K1 condensed in the condensation tank 13 is the produced oil to be recovered. Note that the secondary pyrolysis tank 12 shown in FIG. 1 describes the first example described later.

[0020] The primary pyrolysis tank 10 has a main body portion 21 with a conical bottom, a heater 22A disposed on the outer periphery of the main body portion 21, and a stirrer 23 that stirs the molten plastic P1 heated and melted inside the main body portion 21. In the following description, the molten waste plastic P0 will be referred to as molten plastic P1 with respect to the raw material waste plastic P0. The main body portion 21 is disposed on the upper part of a base 24. The heater 22A is, for example, an infrared heater, a high-frequency coil, or a heating wire. The infrared heater can be formed into an arbitrary shape and is easy to control the temperature. Also, when using a high-frequency coil, the material of the main body portion 21 is made of iron or an iron-based alloy to enable high-frequency heating.

[0021] The agitator 23 consists of a rotating shaft 25, a stirring blade 26 fixed to the bottom end of the main body 21 of the rotating shaft 25, and a motor 27 provided on the outside of the main body 21 to rotate the stirring blade 26. The agitator 23 has the function of stirring the molten plastic P1 with the stirring blade 26 to equalize the temperature of the molten plastic P1, and the function of scraping off the residue of the molten plastic P1 adhering to the bottom of the main body 21. A temperature sensor (not shown) is placed inside the main body 21 to detect the temperature and controls the power supplied to the heater 22A to appropriately manage the internal temperature. The temperature of the primary pyrolysis chamber 10 is 450°C to 500°C.

[0022] An inlet 28 is provided at the top of the main body 21 for introducing an adsorbent such as zeolite into the main body 21. The zeolite has the function of adsorbing moisture and odor (deodorizing) inside the main body 21. Note that the zeolite can be omitted if the waste plastic P0 being introduced has been sufficiently washed and dried. A residue discharge port 29 is provided at the bottom of the main body 21 for removing the residue of the molten plastic P1. Although not shown in the figure, a vent may also be provided to release pyrolysis gas G0 to the outside when the pressure inside the main body 21 exceeds a predetermined level. It is desirable to provide a filter in this vent to remove harmful substances and particles.

[0023] Although not shown in the diagram, the extruder 11 is a so-called screw-type extruder, consisting of a heating cylinder 35 with a heater (such as a band heater) arranged on its outer circumference, and a screw 36 that rotates inside the heating cylinder 35. The waste plastic P0 fed in from the hopper 37 is heated and melted to its fluidization temperature in the heating cylinder 35 and then sent to the primary pyrolysis tank 10 by the screw 36. The temperature inside the heating cylinder 35 is set to 250°C or higher, which is the melting temperature of thermoplastic plastics. Molten plastic P1 is supplied to the primary pyrolysis tank 10 from the extruder 11. By supplying molten plastic P1 to the primary pyrolysis tank 10, fluctuations in the internal temperature of the primary pyrolysis tank 10 are suppressed, and pyrolysis gas G0 can be efficiently generated.

[0024] The screw 36 is rotated in one direction by an externally mounted motor 38. A drive wheel 39 is fixed to the motor 38, and a driven wheel 40 is fixed to the screw 36. A belt 41 is suspended from the drive wheel 39 and the driven wheel 40, and the rotation of the motor 38 is transmitted to the screw 36. The hopper 37 is provided with a feeding aid 42. The feeding aid 42 vibrates the waste plastic P0 in the hopper 37 continuously or periodically to prevent clogging of the hopper 37. The extruder 11 and motor 38 are mounted on a support base 43. It is preferable that the waste plastic P0 be crushed (cut), washed, and dried before being fed into the extruder 11.

[0025] The secondary pyrolysis tank 12 has a cylindrical body 45 that is arranged horizontally (it does not need to be perfectly horizontal). An introduction pipe 46 for introducing pyrolysis gas G0 from the primary pyrolysis tank 10 is connected to the cylindrical body 45, and a pipe 47 for sending the decomposition gas G1 generated in the secondary pyrolysis tank 12 to the condensation tank 13 is connected to it. The introduction pipe 46 and the pipe 47 are each connected to the cylindrical body 45 by flange-type pipe fittings 48, and the cylindrical body 45 is configured to be easily attached to and detached from the introduction pipe 46 and the pipe 47. Although not shown in the figures, an insulating material is wrapped around the introduction pipe 46 near the primary pyrolysis tank 10 to prevent a rapid drop in the temperature of the pyrolysis gas G0. Although not shown in the figures, the temperature controller 49 consists of a heater and a refrigerant supply pipe, and the cooling water W as the refrigerant is supplied from a cooling device (not shown).

[0026] The secondary pyrolysis chamber 12 can also be installed vertically. However, a horizontal arrangement is preferable because it makes it easier to maintain temperature uniformity within the secondary pyrolysis chamber 12.

[0027] In this example, the temperature of the secondary pyrolysis tank 12 is set appropriately within the range of 300°C to 400°C. When the temperature of the secondary pyrolysis tank 12 is set to 300°C, the pyrolysis gas G0 is separated into high-boiling-point liquefied component K0 with n = 17, 18, or 19 in the hydrocarbon molecular formula (CnH2n+2), and low-boiling-point decomposition gas G1 with n = 16 or less. The liquefied component K0 is mainly heavy oil components and accumulates in the lower part of the secondary pyrolysis tank 12 (cylinder 45). In the secondary pyrolysis tank 12, the generation of decomposition gas G1 mixed with the liquefied component K0 is promoted by reheating the liquefied component K0 accumulated in the cylinder 45. Note that fine particles generated in the primary pyrolysis tank 10 are mixed in with the liquefied component K0 and settle in the cylinder 45 by gravity. The secondary pyrolysis tank 12 has a temperature sensor (not shown) that controls the temperature inside the secondary pyrolysis tank 12. The liquefied components K0 containing fine particles that have accumulated in the secondary pyrolysis tank 12 and have not been gasified are discharged from the discharge pipe 50A into the recovery tank 51 and recovered. Although not shown in the figures, it is preferable to place a catalyst such as zeolite in the secondary pyrolysis tank 12 to promote the generation of low-boiling point decomposition gas G1 from high-boiling point liquefied components K0.

[0028] In the primary pyrolysis tank 10, the temperature for pyrolysis of the molten plastic P1 is generally set to 400°C to 450°C, and it is known that the efficiency of pyrolysis of the molten plastic P1 can be increased by raising the temperature to 450°C to 500°C. However, raising the temperature of the primary pyrolysis tank 10 generates carbides, which are mixed with the pyrolysis gas G0 and sent downstream, causing slag to adhere to the inner surface of the inlet pipe 46 and piping 47 downstream of the primary pyrolysis tank 10, and clogging the inlet pipe 46 and piping 47. In the secondary pyrolysis tank 12, the liquefied component K0 containing carbides that has accumulated at the bottom can be recovered, making it possible to raise the temperature of the primary pyrolysis tank 10 to 450°C to 500°C. The configuration of the secondary pyrolysis tank 12 will be described later with reference to Figure 2.

[0029] Furthermore, the decomposition gas G1 may contain high-boiling-point components, and if the decomposition gas G1 is cooled in the pipe 47, it is conceivable that liquefied component K0 will adhere to the inner surface of the pipe 47 as residue. However, by making the diameter of the pipe 47 sufficiently larger than that of the inlet pipe 46, and by controlling the temperature of the decomposition gas G1 passing through the pipe 47 to 270°C to 300°C using a temperature controller 49 installed at the rising section of the pipe 47, the high-boiling-point components contained in the decomposition gas G1 liquefy and fall into the secondary pyrolysis tank 12. The low-boiling-point decomposition gas G1 is sent to the condenser 13. When the temperature of the secondary pyrolysis tank 12 is set to around 400°C, the decomposition gas G1 will have gas components with almost the same composition as the pyrolysis gas G0. Therefore, by installing a temperature controller 49 at the rising section of the pipe 47, the high-boiling-point components are liquefied and returned to the secondary pyrolysis tank 12. The liquefied component K0 that falls into the secondary pyrolysis tank 12 remains in the cylindrical body 45 and is reheated. Since the decomposition gas G1 will pass through the piping 47 downstream of the temperature controller 49, there is no risk of clogging in the piping 47. However, low-boiling-point gas may be generated from the liquefied component K0 recovered in the recovery tank 51. Therefore, the recovery tank 51 and the condenser 13 are connected by piping 50B, and the gas generated in the recovery tank 51 is introduced into the condenser 13.

[0030] The decomposition gas G1 generated in the secondary pyrolysis tank 12 is cooled to 270°C to 300°C by the temperature controller 49 and sent to the condenser tank 13 through the piping 47. A spirally wound cooling pipe 44 is installed on the outside of the condenser tank 13, and cooling water W is supplied spirally from below and discharged from above. The liquefied component K1 condensed in the condenser tank 13 is the generated oil, which is a component of diesel fuel. The condenser tank 13 and the oil storage tank 14 are connected by piping 54, and the liquefied component K1 is sent to the oil storage tank 14 through piping 54. The liquid levels in the condenser tank 13 and the oil storage tank 14 are the same. In addition, the decomposition gas G2 that was not liquefied in the condenser tank 13 is sent to the oil storage tank 14 through piping 52.

[0031] The decomposition gas G2 is cooled to below 50°C in the cooler 61 and sent to the oil storage tank 14. This decomposition gas G2, along with the gas produced in the oil storage tank 14, is sent to the water seal 15 through the piping 55 as decomposition gas G3. Decomposition gas G3 is a combustible gas containing hydrocarbons such as ethane and methane, where n is 5 or less in the molecular formula. Liquid 56 is sealed in the water seal 15. The end of the piping 55 is submerged in the liquid 56. The liquid 56 is, for example, water, and the decomposition gas G3 hardly melts. The decomposition gas G3 floats to the space above the liquid surface and is discharged from the discharge pipe 57. The main role of the water seal 15 is to make the pressure of the system downstream of the primary pyrolysis tank 10 of the oil conversion device 1 dynamic pressure, and the decomposition gases G1, G2, and G3 do not flow back. Since the end of the piping 55 is below the water surface, the pressure at this end is equal to the liquid pressure at the liquid surface of the piping 55. If the tip of pipe 55 is too deep below the water surface, the pressure in the secondary pyrolysis tank 12 will need to be increased, which will reduce the flow efficiency of the decomposition gases G1 and G2. For this reason, the water seal 15 maintains a constant liquid level, and the burial depth of pipe 55 is set to approximately 10 mm. The tip of pipe 55 is also kept below the liquid surface to prevent air from entering the system if the temperature of the system from the primary pyrolysis tank 10 to the condensation tank 13 drops due to some malfunction.

[0032] By equipping the water seal 15, it is possible to prevent the decomposition gas G2, which is a combustible gas, from flowing back into the condenser 13, the secondary pyrolysis tank 12, and the primary pyrolysis tank 10. A liquid trap tank (not shown) may also be provided between the oil storage tank 14 and the water seal 15, and by providing a liquid trap tank, the effect of preventing the backflow of decomposition gas G2 can be enhanced.

[0033] The decomposed gas G3 is introduced to the exhaust gas decomposition treatment device 62 through the water seal 15 and the discharge pipe 57. The exhaust gas decomposition treatment device 62 uses a catalyst to decompose the decomposed gas G3, which is a volatile organic compound, into carbon dioxide and water (water vapor), and discharges it to the outside as exhaust gas Gh. The decomposed gas G3 can also be incinerated in an incinerator or the like before discharge. Next, the configuration of the secondary pyrolysis tank 12 will be further explained in the first and second examples with reference to Figures 2 and 3.

[0034] Figure 2 is a cross-sectional view showing the configuration of a secondary pyrolysis tank 12 according to the first example. The secondary pyrolysis tank 12 has a cylindrical body 45. An introduction pipe 46 for introducing pyrolysis gas G0 from the primary pyrolysis tank 10 and a pipe 47 for sending the decomposition gas G1 generated in the secondary pyrolysis tank 12 to the condensation tank 13 are connected to the cylindrical body 45. An discharge pipe 50A for discharging the separated liquefied component K0 to a recovery tank 51 (see Figure 1) is connected to the lower right side of the cylindrical body 45 as shown in Figure 2. As shown in Figure 2, the cylindrical body 45 has an opening 58 at its left end. The opening 58 is closed by a lid member 59. The lid member 59 is screwed and fixed to the cylindrical body 45 and is configured to be removable. Note that the opening 58 and lid member 59 may be provided at the right end, or at both ends. Furthermore, it is more preferable to place a heat-resistant and chemical-resistant sealing material between the cylindrical body 45 and the lid member 59.

[0035] The cylindrical body 45 is provided with an overflow weir 60 near the upstream side of the discharge pipe 50A to allow liquefied component K0 to overflow. In the following description, the side of the inlet pipe 46 will be referred to as the upstream side with respect to the discharge pipe 50A. The decomposition gas G1 is sent to the condenser 13 through the piping 47. The liquefied component K0 temporarily remains in the secondary pyrolysis tank 12, but by reheating it in the secondary pyrolysis tank 12 at 300°C to 400°C, decomposition gas G1 is generated and introduced into the condenser 13. When the amount of liquefied component K0 exceeds the amount of decomposition gas G1 generated, the liquefied component K0 overflows the overflow weir 60 and is discharged through the discharge pipe 50A to the recovery tank 51 (see Figure 1). In other words, the overflow weir 60 acts as a safety valve to prevent the cylindrical body 45 from being filled with liquefied component K0. Furthermore, in order to maintain the secondary pyrolysis chamber 12 at 300°C to 400°C, heaters 22B are arranged around the cylindrical body 45.

[0036] As shown in Figure 1, the secondary pyrolysis tank 12 (cylindrical body 45) is configured to be detachable from the inlet pipe 46 and piping 47 by pipe fittings 48, so the cylindrical body 45 can be easily removed from the inlet pipe 46 and piping 47. Similarly, although not shown in the figure, the cylindrical body 45 can also be removed from the discharge pipe 50A. Therefore, by removing the cylindrical body 45 from the inlet pipe 46, piping 47 and discharge pipe 57 and removing the lid member 59, the inside of the cylindrical body 45 can be easily cleaned.

[0037] Figure 3 is a cross-sectional view showing the configuration of the secondary pyrolysis tank 12A according to the second example. Components identical to those of the secondary pyrolysis tank 12 are denoted by the same reference numerals as in Figures 1 and 2. The secondary pyrolysis tank 12A has similar functions and operations to the secondary pyrolysis tank 12 of the first example, but enables more efficient generation of decomposition gas G1. The secondary pyrolysis tank 12A has a cylindrical body 45 arranged approximately horizontally. An introduction pipe 46 for introducing pyrolysis gas G0 from the primary pyrolysis tank 10 is connected to the cylindrical body 45, and a pipe 47 for sending the decomposition gas G1 generated in the secondary pyrolysis tank 12A to the condensation tank 13 is connected to it. The introduction pipe 46 and the pipe 47 are connected by flange-type pipe fittings 48, and the cylindrical body 45 can be easily attached to and detached from the introduction pipe 46 and the pipe 47. The openings 58 on both the left and right sides can be limited to one side only.

[0038] As shown in Figure 3, the cylindrical body 45 has openings 58 at both the left and right ends, and the openings 58 are closed by lid members 59. The lid members 59 are detachably fixed to the cylindrical body 45 by pipe fittings 30 such as flanges. It is more preferable to place a heat-resistant and chemical-resistant sealing material between the cylindrical body 45 and the lid members 59. In the second example as well, the inside of the cylindrical body 45 can be easily cleaned by removing the cylindrical body 45 from the inlet pipe 46, piping 47 and outlet pipe 57 and removing the lid members 59.

[0039] The secondary pyrolysis tank 12A has a mesh-like first partition wall 31 with small holes through which gas can pass, dividing it into a region connected to the introduction pipe 46 and a region connected to the oil storage tank 14 via piping 47. The catalyst 32A is arranged on the upper surface of the second partition wall 33 in a manner that allows gas to pass through. The first partition wall 31 can be used with the catalyst 32A supported on both sides or on one side. The catalyst 32A promotes the generation of low-boiling point decomposition gas G1 from high-boiling point gases mixed in the decomposition gas G1 within the secondary pyrolysis tank 12A. For example, synthetic zeolites such as high-silica zeolite can be used as catalyst 32A.

[0040] The secondary pyrolysis tank 12A has a mesh-like second partition wall 33 located below the first partition wall 31, which divides the cylindrical body 45 vertically and has small holes that allow gas or liquid to pass through. The second partition wall 33 is provided to prevent the liquefied component K0 from boiling over. The cylindrical body 45 has an overflow weir 60 that extends from the second partition wall 33 to the bottom near the upstream side of the discharge pipe 50A. In the secondary pyrolysis tank 12A, when the amount of liquefied component K0 exceeds the amount of decomposition gas G1 produced, the liquefied component K0 overflows the overflow weir 60 and is discharged through the discharge pipe 50A. In other words, the overflow weir 60 acts as a safety valve to prevent the cylindrical body 45 from being filled with liquefied component K0.

[0041] A catalyst 32B is placed at the bottom of the cylindrical body 45. The catalyst 32B promotes the generation of low-boiling-point decomposition gas G1 from the liquefied component K0. Catalyst 32B may be the same as catalyst 32A or a different one. Although not shown in the diagram, a temperature sensor is placed inside the cylindrical body 45 to control the power supplied to the heater 22B and appropriately manage the internal temperature. The internal temperature of the secondary pyrolysis tank 12A is controlled to 300°C to 400°C. The high-boiling-point pyrolysis gas G0 generated in the primary pyrolysis tank 10 is cooled to 270°C to 300°C by the temperature controller 49 (see Figure 1) and temporarily remains in the secondary pyrolysis tank 12A as liquefied component K0. The liquefied component K0 passes through the mesh of the second partition wall 33 and accumulates at the bottom, and is reheated to 300°C to 400°C to generate low-boiling-point decomposition gas G1.

[0042] As explained above, the pyrolysis gas G0 obtained by thermally decomposing waste plastic P0 has a molecular formula of C n H 2n+2 This is a hydrocarbon represented by [formula]. Here, when a high-boiling point pyrolysis gas G0 is pyrolyzed to produce a low-boiling point decomposition gas G1, the long chains in the chemical formula become unstable due to a lack of hydrogen H at both ends. Therefore, hydrogen H or hydrogen ions H are placed in the cylindrical body 45. + A hydrogen inlet 20 is provided for introducing hydrogen.

[0043] Oil conversion apparatus 1 is an example for recovering light oil as the resulting oil, but it can be applied to oil conversion apparatus 2 for recovering various types of resulting oils. This will be explained with reference to Figure 4 as application example 1.

[0044] (Application Example 1) Figure 4 is a simplified diagram illustrating the configuration of the oil converter 2 according to Application Example 1. Note that in Figure 4, parts common to oil converter 1 are denoted by the same reference numerals as in Figure 1. In the configuration of Application Example 1, the configuration from the primary pyrolysis tank 10 to the oil storage tank 14 is the same as the configuration example in Figure 1. As shown in Figure 4, the oil converter 2 has the primary pyrolysis tank 10, followed by the secondary pyrolysis tank 12, condenser 13, second condenser 65, and third condenser 66, all arranged almost horizontally. The configuration from the primary pyrolysis tank 10 to the secondary pyrolysis tank 12, condenser 13, and oil storage tank 14 is the same as in oil converter 1, so its explanation is omitted. The liquefied component K1 condensed in the condenser 13 is light oil. The liquefied component K1 is cooled to 50°C or below in the cooler 61 and sent to the oil storage tank 14. The configurations of the condenser 13, second condenser 65, and third condenser 66 are the same, but their controlled temperatures differ.

[0045] The decomposition gas G2 that was not liquefied in the condenser 13, and the gas generated in the oil storage tank 14, are sent to the second condenser 65 and condensed at a predetermined temperature. The condensed liquefied component K2 is cooled to below 50°C in the cooler 61 and stored in the oil storage tank 67 as the generated oil. The decomposition gas G4 that was not liquefied in the second condenser 65, and the gas generated in the oil storage tank 67, are sent to the third condenser 66 and condensed at a predetermined temperature. The condensed liquefied component K3 is cooled to below 50°C in the cooler 61 and stored in the oil storage tank 68 as the generated oil. The decomposition gas G4 that was not liquefied in the third condenser 66, and the gas generated in the oil storage tank 68, are sent to the water sealer 15, where they are decomposed into carbon dioxide and water (water vapor) in the exhaust gas decomposition treatment device 62 (see Figure 1) and discharged to the outside.

[0046] For example, if the temperature of condenser 13 is set to 300°C, the liquefied component K1 produced is diesel fuel. If the temperature of the second condenser 65 is set to 190°C to 260°C, the liquefied component K2 produced is kerosene. If the temperature of the third condenser 66 is set to 60°C to 170°C, the liquefied component K3 produced is gasoline. Temperature controllers 49 are installed upstream of condenser 13, the second condenser 65, and the third condenser 66, respectively, to cool the decomposition gases G1, G2, and G3 before they enter each condenser to the same temperature as the set temperature of each condenser.

[0047] The oil conversion apparatus 1 described above includes an extruder 11 that melts and feeds the raw material, waste plastic P0; a primary pyrolysis tank 10 that thermally decomposes the molten plastic P1 to generate pyrolysis gas G0; and a secondary pyrolysis tank 12 that separates the pyrolysis gas G0 into a low-boiling point decomposition gas G1 and a high-boiling point liquefied component K0, and heats the liquefied component K0 to generate the low-boiling point decomposition gas G1. The oil conversion apparatus 1 also includes a condenser 13 that collects and condenses the decomposition gas G1; an oil storage tank 14 that stores the liquefied component K1 as the generated oil condensed in the condenser 13; a pipe 47 connecting the secondary pyrolysis tank 12 and the condenser 13; and a pipe 52 connecting the condenser 13 and the oil storage tank 14.

[0048] The oil converter 1 heats and decomposes waste plastic P0 in the primary pyrolysis tank 10, cools the generated pyrolysis gas G0, and introduces it into the secondary pyrolysis tank 12, where it separates the decomposition gas G1 from the high-boiling-point liquefied component K0. The secondary pyrolysis tank 12 further heats the accumulated liquefied component K0 to generate decomposition gas G1. The decomposition gas G1 is condensed in the condensation tank 13 and recovered as useful liquefied component K1 such as diesel fuel. The liquefied component K0 that remains in the secondary pyrolysis tank 12 and is not gasified after heating is recovered in the recovery tank 51 along with settled fine particles. Therefore, it is possible to prevent clogging caused by high-boiling-point components adhering as slag to the inner surface of the piping 47 downstream from the secondary pyrolysis tank 12. As a result, the oil converter 1 can reduce downtime for maintenance and increase its operating rate. Furthermore, by providing a secondary pyrolysis tank 12, the temperature of the primary pyrolysis tank 10 can be raised to 450°C to 500°C, thereby accelerating the thermal decomposition of waste plastic P0.

[0049] The secondary pyrolysis tank 12 also includes a horizontally arranged cylindrical body 45, a removable lid member 59 provided at at least one opening 58 at the horizontal end of the cylindrical body 45, and a heater 22B arranged around the cylindrical body 45. An introduction pipe 46 for introducing pyrolysis gas G0 from the primary pyrolysis tank 10 to the secondary pyrolysis tank 12, and a pipe 47 connecting the secondary pyrolysis tank 12 and the condensation tank 13 are detachably connected to the upper part of the cylindrical body 45 by pipe fittings 48. An exhaust pipe 50A for discharging liquefied components K0 to the outside is connected to the lower part of the cylindrical body 45.

[0050] By arranging the secondary pyrolysis tank 12 (cylindrical body 45) horizontally, it is possible to maintain a uniform temperature inside the secondary pyrolysis tank 12, enabling efficient separation of the pyrolysis gas G0 into decomposition gas G1 and liquefied component K0. The secondary pyrolysis tank 12 has a heater 22B that reheats the liquefied component K0 accumulated at the bottom to generate decomposition gas G1. Furthermore, the secondary pyrolysis tank 12 can be easily removed from the inlet pipe 46 and piping 47, and the inside of the cylindrical body 45 can be easily cleaned by removing the lid member 59.

[0051] Furthermore, the cylindrical body 45 is provided with an overflow weir 60 upstream of the discharge pipe 50A, which allows the liquefied component K0 that has accumulated inside the cylindrical body 45 to overflow. This liquefied component K0 is temporarily retained in the secondary pyrolysis tank 12 by the overflow weir 60. By reheating the liquefied component K0, a low-boiling-point decomposition gas G1 is generated. However, when the amount of liquefied component K0 exceeds the amount of decomposition gas G1 generated, the liquefied component K0 overflows the overflow weir 60 and is discharged from the discharge pipe 50A. Therefore, the inside of the cylindrical body 45 is never completely filled with liquefied component K0, and the generation of decomposition gas G1 in the secondary pyrolysis tank 12 can be promoted.

[0052] The secondary pyrolysis tank 12A in the second example has a first partition wall 31 that divides the inside of the cylindrical body 45 into a region connected to the inlet pipe 46 and a region connected to the piping 47, and has small holes through which gas can pass. Furthermore, the secondary pyrolysis tank 12A has a second partition wall 33 below the first partition wall 31 that divides the inside of the cylindrical body 45 vertically and has small holes through which gas and liquid can pass. Catalyst 32A is placed in the first partition wall 31, and catalyst 32B is placed at the bottom of the cylindrical body 45.

[0053] Catalyst 32B promotes the generation of low-boiling-point decomposition gas G1 from liquefied component K0. The decomposition gas G1 generated by the thermal decomposition of liquefied component K0 may contain high-boiling-point components. Therefore, catalyst 32A decomposes the high-boiling-point components contained in the decomposition gas G1 to generate a low-boiling-point decomposition gas G1, which is then sent to the condenser 13.

[0054] Furthermore, the liquefaction device 1 also includes a water seal 15 for introducing decomposition gas G2 that was not liquefied in the condenser 13, and an exhaust gas decomposition treatment device 62 for discharging the decomposition gas G3 that has passed through the water seal 15 to the outside. The water seal 15 maintains a constant liquid level and keeps the end of the piping 55 below the liquid level, thereby preventing air from entering the system when the temperature of the system from the primary pyrolysis tank 10 to the condenser 13 drops due to some malfunction. In addition, the exhaust gas decomposition treatment device 62 can decompose combustible gases such as methane and ethane into carbon dioxide and water (water vapor) using a catalyst and discharge them, thereby suppressing environmental pollution.

[0055] Furthermore, the oil conversion device 2 includes a second condenser 65 into which the decomposition gas G1 that was not liquefied in the condenser 13 is introduced and condensed at a lower temperature than the condenser 13, and a third condenser 66 into which the decomposition gas G2 that was not liquefied in the second condenser 65 is introduced and condensed at a lower temperature than the second condenser 65.

[0056] Since the oil converter 2 has condensing tanks 13, a second condensing tank 65, and a third condensing tank 66 with different condensation temperatures, it is possible to produce multiple types of liquefied oils, such as K1, K2, and K3, that can be condensed at each condensation temperature. The oil converter 2 reheats the high-boiling-point liquefied oil component K0 (heavy oil component) in the secondary pyrolysis tank 12 to produce decomposition gas G1, which prevents clogging of the piping 47 downstream of the secondary pyrolysis tank 12, and also prevents clogging of filters if there are filters. In Application Example 1, an example was given and explained in which three types of liquefied oil components K1 (light oil), K2 (kerosene), and K3 (gasoline) are produced, but by increasing the number of condensing tanks and setting the condensation temperature differences more precisely, it is possible to obtain liquefied oils that can be used for an even wider variety of applications. [Explanation of symbols]

[0057] 1,2... Oil conversion equipment (waste plastic oil conversion equipment), 10... Primary pyrolysis tank, 11... Extruder, 12,12A... Secondary pyrolysis tank, 13... Condenser, 14,67,68... Oil storage tank, 15... Water seal, 20... Hydrogen inlet, 21... Main body, 31... First partition, 32A,32B... Catalyst, 33... Second partition, 35... Heating cylinder, 36... Screw, 44... Cooling pipe, 45... Cylindrical body, 46... Inlet pipe, 47,50B,52,54,55... Piping, 48... Pipe joint Hand, 49...Temperature controller, 50A, 57...Discharge pipe, 51...Recovery tank, 56...Liquid (water), 58...Opening, 59...Lid member, 60...Overflow weir, 61...Cooler, 62...Exhaust gas decomposition treatment device, 65...Second condenser, 66...Third condenser, P0...Waste plastic, P1...Molten waste plastic, G0...Pyrolysis gas, G1, G2, G3, G4...Decomposition gas, Gh...Exhaust gas, K0...Liquefied components, K1, K2, K3...Liquefied components (produced oil).

Claims

1. An extruder that melts and feeds the waste plastic, which is the raw material, A primary pyrolysis tank that thermally decomposes the molten waste plastic to generate pyrolysis gas, A secondary pyrolysis vessel that cools the pyrolysis gas to separate it into a low-boiling point decomposition gas and a high-boiling point liquefied component, and heats the liquefied component to generate the low-boiling point decomposition gas, A condenser for collecting and condensing the low-boiling point decomposition gas, A storage tank for storing the generated oil that is condensed and produced in the aforementioned condensation tank, The piping connecting the secondary pyrolysis tank and the condensation tank, and the piping connecting the condensation tank and the oil storage tank, It has, A waste plastic oil conversion apparatus characterized by the following features.

2. In the waste plastic oil conversion apparatus described in claim 1, The secondary pyrolysis tank comprises a horizontally arranged cylindrical body, a removable lid member provided at at least one opening at the horizontal end of the cylindrical body, and a heater arranged around the cylindrical body. An introduction pipe for introducing the pyrolysis gas from the primary pyrolysis tank to the secondary pyrolysis tank, and the piping connecting the secondary pyrolysis tank and the condenser tank are detachably connected to the upper part of the cylindrical body by pipe fittings. A discharge pipe is connected to the cylindrical body for discharging the liquefied components that have accumulated inside the cylindrical body to the outside. A waste plastic oil conversion apparatus characterized by the following features.

3. In the waste plastic oil conversion apparatus described in claim 2, The cylindrical body is provided with an overflow weir upstream of the discharge pipe to allow the liquefied components accumulated inside the cylindrical body to overflow. A waste plastic oil conversion apparatus characterized by the following features.

4. In the waste plastic oil conversion apparatus described in claim 2, The secondary pyrolysis tank further comprises a first partition wall that divides the interior of the cylindrical body into a region connected to the inlet pipe and a region connected to the piping, and has small holes through which gas can pass, and a second partition wall located below the first partition wall that divides the interior of the cylindrical body vertically and has small holes through which gas and liquid can pass. A catalyst is disposed in at least one of the first partition wall or the bottom of the cylindrical body. A waste plastic oil conversion apparatus characterized by the following features.

5. In the waste plastic oil conversion apparatus according to claim 1, The system further includes a water seal for introducing the decomposition gas that was not liquefied in the condenser, and an exhaust gas decomposition treatment device connected to the water seal for discharging the decomposition gas introduced into the water seal to the outside. A waste plastic oil conversion apparatus characterized by the following features.

6. In the waste plastic oil conversion apparatus described in claim 1, A second condenser, into which the decomposition gas that was not liquefied in the aforementioned condenser is introduced and condensed at a lower temperature than the aforementioned condenser, A third condenser is provided, which introduces the decomposition gas that was not liquefied in the second condenser and condenses it at a lower temperature than the second condenser. It also has, A waste plastic oil conversion apparatus characterized by the following features.

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