Waste plastic treatment facility and waste plastic treating method

Abstract

This waste plastic treatment facility comprises: a wind power sorting device (10) to which waste plastic is supplied; a means (20) for agglomerating waste plastic separated as low-density objects in the wind power sorting device (10); and a coke oven (30) into which the agglomerated waste plastic and waste plastic separated as high-density objects in the wind power sorting device (10) are charged and which thermally decomposes the waste plastics.

Description

Waste plastic processing equipment and waste plastic processing method

[0001] The present invention relates to a waste plastic treatment facility and a waste plastic treatment method.

[0002] There is a known technology for recycling waste plastics by carbonizing coal in a coke oven to produce coke and pyrolyzing the waste plastics. For example, Patent Document 1 describes a technology in which waste plastics are charged into a space formed at the top of a coke oven and pyrolyzed. The waste plastics may be mixed in advance with the coal to be charged into the coke oven.

[0003] Patent No. 2967329

[0004] When waste plastics are treated in a coke oven as described above, the waste plastics are agglomerated, for example, by extrusion molding or by thermal volume reduction, before being charged into the coke oven so that small pieces of waste plastics are not discharged untreated mixed in with the exhaust gas (COG: coke oven gas). However, in this case, the agglomeration process may become a bottleneck, making it impossible to increase the amount of waste plastics that can be treated.

[0005] Therefore, an object of the present invention is to provide a waste plastic processing facility and a waste plastic processing method that can increase the processing volume by reducing the amount of waste plastic that is agglomerated before being charged into a coke oven when recycling waste plastic by thermal decomposition in a coke oven.

[0006] [1] A waste plastic treatment facility comprising: an air sorting device to which waste plastics are supplied; a means for agglomerating the waste plastics separated as light fractions in the air sorting device; and a coke oven into which the waste plastics separated as heavy fractions in the air sorting device and the agglomerated waste plastics are charged and which thermally decomposes the waste plastics. [2] The coke oven carbonizes coal and thermally decomposes the waste plastics, and the waste plastics separated as heavy fractions and the agglomerated waste plastics are charged into an internal space formed above the coal during the carbonization of the coal. [3] The waste plastic treatment facility according to [1], wherein the waste plastics separated as heavy fractions and the agglomerated waste plastics are charged into an internal space including the hearth of the coke oven. [4] The coke oven further includes a means for carbonizing coal and thermally decomposing the waste plastics, and mixing the separated heavy materials and the agglomerated waste plastics into the coal, and the coal mixed with the waste plastics is charged into the coke oven. [1] Waste plastic processing equipment according to [1]. [5] The waste plastics treatment facility according to any one of [1] to [5], wherein the coke oven further comprises a means for carbonizing coal and thermally decomposing the waste plastics, and mixing at least a portion of at least one of the waste plastics separated as heavy fractions and the agglomerated waste plastics into the coal, wherein the coal mixed with at least a portion of the waste plastics separated as heavy fractions and the agglomerated waste plastics is charged into the coke oven, and the waste plastics separated as heavy fractions and the agglomerated waste plastics that have not been mixed into the coal are charged into a furnace space formed above the coal during the carbonization of the coal mixed with at least a portion of the waste plastics separated as heavy fractions and the agglomerated waste plastics. [6] The waste plastics treatment facility according to any one of [1] to [5], wherein the air sorting device has a vertical sorting column.[7] The waste plastic treatment facility according to any one of [1] to [5], wherein the means for agglomerating the waste plastics includes an extrusion molding machine. [8] A method for treating waste plastics, comprising: a step of separating waste plastics into heavy fractions and light fractions by air sorting; a step of agglomerating the light fraction; and a step of charging the heavy fractions and the agglomerated waste plastics into a coke oven and pyrolyzing the waste plastics in the coke oven. [9] The method for treating waste plastics according to [8], wherein the coke oven pyrolyzes coal and pyrolyzes the waste plastics charged therein, and charges the heavy fractions and the agglomerated waste plastics into an internal space formed above the coal during the pyrolysis of the coal.

[10] The method for treating waste plastics according to [8], wherein the heavy fractions and the agglomerated waste plastics are charged into an internal space including the hearth of the coke oven.

[11] The method for processing waste plastics described in [8], further comprising the steps of carbonizing coal and thermally decomposing the waste plastics charged into the coke oven, and mixing the waste plastics separated as heavy materials and the agglomerated waste plastics into the coal, and charging the coal mixed with the waste plastics into the coke oven.

[12] The method for treating waste plastics described in [8], further comprising the steps of carbonizing coal and thermally decomposing the waste plastics charged into the coke oven, and mixing at least a portion of at least either the waste plastics separated as heavy fractions or the agglomerated waste plastics into the coal, wherein the coal mixed with at least a portion of the waste plastics separated as heavy fractions and the agglomerated waste plastics is charged into the coke oven, and the waste plastics separated as heavy fractions and the agglomerated waste plastics that have not been mixed into the coal are charged into a furnace space formed above the coal during the carbonization of the coal mixed with at least a portion of the waste plastics separated as heavy fractions and the agglomerated waste plastics.

[13] The coke oven has a riser pipe through which gas inside the oven is discharged, and the method for treating waste plastics described in any one of [8] to

[12] further includes a step of calculating the drag force acting on floating matter in the riser pipe based on measurement results of the temperature, flow rate and composition of the gas in the riser pipe, and a step of setting the air flow rate in the wind sorting so that the waste plastics are subjected to the same drag force as in the riser pipe.

[0007] FIG. 1 is a diagram showing the overall configuration of a waste plastics treatment facility according to a first embodiment of the present invention. FIG. 2 is an enlarged view of an air separation device shown in FIG. 1. FIG. 3 is an enlarged view of a coke oven shown in FIG. 1. FIG. 4 is a diagram showing the overall configuration of a waste plastics treatment facility according to a second embodiment of the present invention. FIG. 5 is an enlarged view of a coke oven shown in FIG. 6. FIG. 6 is a diagram showing the overall configuration of a waste plastics treatment facility according to a fourth embodiment of the present invention. FIG. 7 is a diagram showing a modified example of the waste plastics treatment facility shown in FIG. 8. FIG. 9 is an enlarged view of a coke oven shown in FIG. 9. FIG. 10 is a graph showing the recovery rate for each flow velocity in air separation in an example. FIG. 11 is a graph showing measurement results of the thickness of waste plastics separated by air separation in an example. FIG. 12 is a diagram showing the simulation results of the scattering state inside a coke oven.

[0008] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0009] First Embodiment FIG. 1 is a diagram showing the overall configuration of a waste plastic treatment facility according to a first embodiment of the present invention. In this specification, waste plastic refers to waste primarily composed of plastic, including, for example, polystyrene (PS), polyethylenes (PE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polyvinylidene chloride (PVDC). In the illustrated example, the treatment facility 1 includes an air sorting device 10 to which the waste plastic is supplied, an extrusion molding machine 20 for agglomerating the waste plastic separated as light fraction W2 in the air sorting device 10, and a coke oven 30 to which waste plastic W, which is a combination of the waste plastic separated as heavy fraction W1 in the air sorting device 10 and the waste plastic agglomerated by the extrusion molding machine 20, is charged. As will be described later, in this embodiment, the waste plastic W is charged into an empty space formed above the coal C during the carbonization of the coal C. The vaporized materials such as combustible gases, tar, and light oil generated by the carbonization (thermal decomposition) of coal C and waste plastic W are recovered as COG (coke oven gas), and the solid coke is transported from the coke oven 30 after the carbonization is completed.

[0010] The means for supplying the waste plastics separated in the wind sorting device 10 to the extruder 20, the means for charging the coal and waste plastics into the coke oven 30, and the means for recovering and transporting the gas and solids generated in the coke oven 30 can be appropriately implemented using coal charging cars, conveyors, hoppers, feeders, and the like used in known waste plastic processing facilities, and detailed descriptions thereof will be omitted. The extruder 20 is an example of a means for agglomerating waste plastics, and for example, a screw-type extruder mixes and kneads the waste plastics to generate heat and compress them, thereby fusing the pieces of waste plastic together. In addition, various devices used for agglomerating or granulating waste plastics, such as thermal volume reduction using a furnace such as a rotary kiln, can also be used for agglomerating waste plastics.

[0011] FIG. 2 is an enlarged view of the pneumatic sorting apparatus shown in FIG. 1 . The pneumatic sorting apparatus 10 in the illustrated example has a vertical sorting column 12. While the pneumatic sorting apparatus according to the present invention is not necessarily limited to one having a vertical sorting column, a pneumatic sorting apparatus having a vertical sorting column has the advantage of high classification accuracy. In the pneumatic sorting apparatus 10, waste plastic is fed into the sorting column 12 by a feeder 11, and separated into heavy fraction W1 and light fraction W2 by an airflow generated within the sorting column 12 by the operation of a suction blower 13. The heavy fraction W1 falls through the sorting column 12 and is collected. The light fraction W2 is blown up by the airflow within the sorting column 12 and separated from the airflow in a cyclone chamber 14 for collection. Here, as described above, the waste plastic separated as heavy fraction W1 is charged into a coke oven 30 without being agglomerated. Therefore, the flow velocity of the airflow in the sorting column 12 needs to be set so that the waste plastics of the heavy material W1 do not enter the COG recovery processing path untreated after being charged into the coke oven 30. In this embodiment, the flow velocity at a position P above the outlet of the feeder 11 of the sorting column 12 is set by a calculation method to be described later.

[0012] In this specification, it is described that waste plastics are separated into heavy waste W1 and light waste W2 by air sorting, but the terms "heavy waste" and "light waste" do not necessarily mean that the specific gravities of these waste plastics are different. These waste plastics may have the same specific gravity as a material, for example, but are separated into heavy waste (the side that falls) and light waste (the side that scatters and is collected) in air sorting due to differences in dimensions such as thickness after crushing.

[0013] 3 is an enlarged view of the coke oven shown in FIG. 1. The coke oven 30 is a furnace for producing coke by carbonizing charged coal C. Waste plastics W are charged from a charging port 31 at the top of the furnace into an in-furnace space SP formed above the coal C during carbonization of the coal C. The in-furnace space SP above the coal C is formed as the coal C contracts during carbonization in the coke oven 30. Therefore, the waste plastics W are charged into the coke oven 30 after a predetermined time has elapsed since the carbonization of the coal C in the coke oven 30 began. Vaporized materials such as combustible gases, tar, and diesel fuel generated by the carbonization (pyrolysis) of the coal C and the waste plastics W are recovered as COG via a riser pipe 32.

[0014] A common feature of the embodiments described below is that during processing in the coke oven 30, if waste plastics W that have not yet been pyrolyzed are scattered by the ascending air currents in the oven and rise up the riser pipe 32, the waste plastics W may be mixed into the gas recovery processing path following the riser pipe 32, which may affect the quality of the recovered diesel fuel or cause clogging of equipment such as nozzles. As described above, in this embodiment, the waste plastics separated as light materials W2 in the pneumatic sorting device 10 are agglomerated and then charged into the coke oven 30, thereby preventing the scattering of waste plastics in the coke oven 30. Furthermore, as described below, by setting the airflow velocity in the pneumatic sorting device 10 to a range that prevents the waste plastics in the heavy materials W1 from rising up the riser pipe 32, the effects of the scattering of waste plastics as described above can be more reliably reduced.

[0015] Second Embodiment Next, a second embodiment of the present invention will be described. Coke ovens are generally constructed as a furnace battery in which a large number of furnaces (carbonization chambers) and combustion chambers that heat them are arranged alternately. However, some furnaces in a furnace battery may become unsuitable for coke production due to aging or other reasons. Even such furnaces are heated together with adjacent furnaces, which can be wasteful from the perspective of energy efficiency. Furthermore, depending on the coke supply and demand situation, it may not be necessary to produce coke in all furnaces in the furnace battery. Therefore, in this embodiment, coke ovens that are not producing coke for reasons such as those described above are effectively utilized to increase the amount of waste plastic processed.

[0016] 4 is a diagram showing the overall configuration of a waste plastic processing facility according to a second embodiment of the present invention. In the illustrated example, the processing facility 2 includes a wind-powered sorting device 10 to which waste plastic is supplied, an extrusion molding machine 20 for agglomerating the waste plastic separated as light materials W2 in the wind-powered sorting device 10, and a coke oven 30 to which waste plastic W, a combination of the waste plastic separated as heavy materials W1 in the wind-powered sorting device 10 and the waste plastic agglomerated in the extrusion molding machine 20, is charged. In this embodiment, no coal is charged into the coke oven 30. Vaporized materials such as combustible gases, tar, and diesel fuel generated by the pyrolysis (pyrolysis) of the waste plastic W in the coke oven 30 are recovered in the same manner as COG (coke oven gas) during coke production, and the solids are removed from the coke oven 30 after the carbonization is completed.

[0017] As in the other embodiments, the means for supplying the waste plastics separated in the air sorting device 10 to the extruder 20, the means for charging the waste plastics into the coke oven 30, and the means for recovering and transporting the gas and solids generated in the coke oven 30 can be conveyors, hoppers, feeders, or the like used in known waste plastic processing facilities, and detailed descriptions thereof will be omitted. The extruder 20 is an example of a means for agglomerating waste plastics, and for example, a screw-type extruder mixes and kneads the waste plastics to generate heat and compress them, thereby fusing the pieces of waste plastic together. In addition, various devices used for agglomerating or granulating waste plastics, such as a rotary kiln or other furnace for thermal volume reduction, can be used for agglomerating waste plastics.

[0018] Figure 5 is an enlarged view of the coke oven shown in Figure 4. A coke oven 30 is originally a furnace for producing coke by carbonizing charged coal. However, the coke oven 30 shown in the figure is not producing coke due to, for example, aging or supply-demand conditions, and therefore no coal is charged. In the coke oven 30, waste plastics W are charged into the furnace through a charging port 31 at the top of the furnace. Since no coal is charged, the waste plastics W are charged into the furnace space SP, which includes the furnace bottom B of the coke oven 30. As mentioned above, since only some of the furnaces in the furnace battery do not produce coke, waste plastics may be charged together with coal and pyrolyzed in the other furnaces. The timing for charging the waste plastics W into the coke oven 30 of this embodiment is not particularly limited, but for example, if other coke ovens in the oven battery that is producing coke also pyrolyze waste plastics, the waste plastics W may be charged into the coke oven 30 at the same time as the waste plastics are charged into the space inside the other oven that is formed by the carbonization and shrinkage of coal inside the oven. Vaporized materials such as combustible gases, tar, and diesel oil generated by the carbonization (thermal decomposition) of the waste plastics W are recovered via the riser pipe 32 in the same way as COG.

[0019] The above-described coke oven 30 has a larger furnace space SP into which waste plastics W are charged than the furnace space formed above the coal during carbonization in other coke ovens that produce coke. Therefore, the amount of waste plastics W charged into the coke oven 30 can be increased compared to other coke ovens. In this case, for example, the amount of waste plastics W charged through the charging port 31 at the top of the oven can be increased, or the waste plastics W can be charged through a route (not shown) used for charging coal in other ovens in addition to or instead of the charging port 31. Even if the same amount of waste plastics W is charged into a coke oven 30 that does not produce coke as into other coke ovens that do, the amount of waste plastics processed can be increased compared to, for example, when the oven that does not produce coke is not used for processing waste plastics. Therefore, the amount of waste plastics W charged into the coke oven 30 in this embodiment of the present invention is not necessarily limited to an amount greater than that of other coke ovens that produce coke.

[0020] Third Embodiment Fig. 6 is a diagram showing the overall configuration of a waste plastic treatment facility according to one embodiment of the present invention. In the illustrated example, the treatment facility 3 includes an air sorting device 10 to which waste plastic is supplied, an extrusion molding machine 20 for agglomerating the waste plastic separated as light fraction W2 in the air sorting device 10, a coal mixer 40 for mixing the waste plastic W, which is a combination of the waste plastic separated as heavy fraction W1 in the air sorting device 10 and the waste plastic agglomerated in the extrusion molding machine 20, with coal C, and a coke oven 30 into which the coal (C+W) containing the waste plastic is charged. Vaporized materials such as combustible gas, tar, and diesel oil generated by the carbonization (pyrolysis) of the coal C and the waste plastic W are recovered as coke oven gas (COG), and the solid coke is discharged from the coke oven 30 after the carbonization is completed.

[0021] As in the other embodiments, the means for supplying the waste plastics separated in the wind sorting device 10 to the extruder 20, the means for supplying the waste plastics to the coal mixer 40, the means for charging the coal mixed with the waste plastics into the coke oven 30, and the means for recovering and transporting the gas and solids generated in the coke oven 30 can be coal charging cars, conveyors, hoppers, feeders, and the like used in known waste plastic processing facilities, and detailed descriptions thereof will be omitted. The extruder 20 is an example of a means for agglomerating waste plastics. For example, the waste plastics are kneaded in a screw extruder to generate heat and compress them, fusing the pieces of waste plastic together. In addition, various devices used for agglomerating or granulating waste plastics, such as thermal volume reduction using a furnace such as a rotary kiln, can be used for agglomerating waste plastics.

[0022] FIG. 7 is an enlarged view of the coke oven shown in FIG. 6 . The coke oven 30 is a furnace for producing coke by carbonizing charged coal C. In this embodiment, waste plastic W is premixed with the coal C (C+W) as described above. For example, if it is necessary to increase the amount of waste plastic to be processed, additional waste plastic (not shown in FIG. 6 ) may be charged into the furnace space formed above the coal C during the carbonization of the coal C and the waste plastic W through a charging port 31 at the top of the furnace. This charging of the additional waste plastic is performed a predetermined time after the start of carbonization of the coal C in the coke oven 30. Vaporized materials such as combustible gas, tar, and diesel fuel generated by the carbonization (pyrolysis) of the coal C and the waste plastic W are recovered as COG via a riser 32.

[0023] (Fourth Embodiment) FIG. 8 is a diagram showing the overall configuration of a waste plastic treatment facility according to a fourth embodiment of the present invention. In the illustrated example, the treatment facility 4 includes an air separator 10 to which waste plastic is supplied, an extruder 20 for agglomerating the waste plastic separated as light materials W2 in the air separator 10, a coal mixer 40 for mixing a portion (W2-1) of the waste plastic agglomerated by the extruder 20 into coal C, and a coke oven 30 into which the coal mixed with the waste plastic (C+W2) and the waste plastic not mixed into the coal are separately charged. Specifically, the waste plastic not mixed into the coal is the waste plastic separated as heavy materials W1 in the air separator 10 and the remaining portion (W2-2) of the waste plastic agglomerated by the extruder 20. These waste plastics are charged into a furnace space formed above the coal C during the dry distillation of the coal and waste plastic mixture (C+W2). The vaporized materials such as combustible gases, tar, and light oil generated by the carbonization (thermal decomposition) of coal C and waste plastic W are recovered as COG (coke oven gas), and the solid coke is transported from the coke oven 30 after the carbonization is completed.

[0024] As in the other embodiments, the means for supplying the waste plastics separated in the air sorting device 10 to the extruder 20, the means for supplying the waste plastics to the coal blender 40, the means for charging the coal containing the waste plastics or the waste plastics not mixed in the coal into the coke oven 30, and the means for recovering and transporting the gas and solids generated in the coke oven 30 can be appropriately implemented using coal charging cars, conveyors, hoppers, feeders, and the like used in known waste plastic processing facilities, and detailed descriptions thereof will be omitted. The extruder 20 is an example of a means for agglomerating the waste plastics. For example, the waste plastics are kneaded in a screw extruder to generate heat and compress them, fusing the pieces of waste plastic together. In addition, various devices used for agglomerating or granulating waste plastics, such as thermal volume reduction using a furnace such as a rotary kiln, can be used for agglomerating the waste plastics.

[0025] Fig. 9 is a diagram showing a modified example of the waste plastic treatment facility shown in Fig. 8. In the example shown, all of the waste plastics W2 agglomerated by the extruder 20 are mixed with the coal C by the coal mixer 40. In this case, only the waste plastics separated as heavy materials W1 by the air separator 10 are directly charged into the coke oven 30 without being mixed with the coal. For example, if the ratio of heavy materials W1 in the waste plastics brought into the treatment facility 1 is higher than in the example of Fig. 8, the heavy materials W1 and the agglomerated waste plastics W2 may be charged into the coke oven 30 in different ways.

[0026] 8 and 9 , in another embodiment, a part of the heavy material W1 may be mixed with the coal C, and the remainder of the heavy material W1 and the agglomerated waste plastics W2 may be directly charged to the coke oven 30, or all of the heavy material W1 may be mixed with the coal C, and the agglomerated waste plastics W2 may be directly charged to the coke oven 30. Alternatively, the heavy material W1 and the agglomerated waste plastics W2 may be mixed and then separated into a part to be mixed with the coal C and a part to be directly charged to the coke oven 30. As described above, in the embodiment of the present invention, a part of the heavy material W1 and the agglomerated waste plastics W2 are mixed with the coal C, and the remainder not mixed with the coal C is directly charged to the coke oven 30. However, whether or not the heavy material W1 and the agglomerated waste plastics W2 are included in the waste plastics in each charging method, and the proportions thereof when included, are not particularly limited. In other words, in this embodiment, at least a portion of at least either the waste plastic separated as heavy materials W1 in the air sorting device 10 or the agglomerated waste plastic W2 is mixed with the coal C in the coal mixer 40.

[0027] The third and fourth embodiments described above with reference to Fig. 6 can be selectively used depending on, for example, the amount of waste plastics that needs to be processed. In this case, for example, when the amount of waste plastics to be processed is small, the heavy material W1 and the entire amount of agglomerated waste plastics are mixed with coal C in the configuration shown in Fig. 6. In this case, the procedure of charging waste plastics after starting carbonization of coal C in the coke oven 30 can be omitted. When the amount of waste plastics to be processed increases and exceeds the upper limit of the amount that can be mixed with coal C, which is set to ensure the quality of the coke, the configuration shown in Fig. 8 or Fig. 9 can be used, and the waste plastics that exceed the upper limit can be charged into the space formed above the coal during the carbonization of the mixture of coal and waste plastics, thereby maximizing the amount of waste plastics that can be processed.

[0028] FIG. 10 is an enlarged view of the coke oven shown in FIG. 9 . As in other embodiments, the coke oven 30 is a furnace for producing coke by carbonizing charged coal C. For convenience, the example of FIG. 9 will be described, in which the heavy material W1 and the agglomerated waste plastic W2 are charged separately. However, the same applies to other examples such as FIG. 8 . In the example of FIG. 9 , the waste plastic W2 is pre-mixed with the coal C (C+W2) as described above. Furthermore, the waste plastic W1 is charged through a charging port 31 at the top of the furnace into a furnace space SP formed above the coal C during the carbonization of the mixture of coal C and waste plastic W2. The furnace space SP is formed by the carbonization and shrinkage of the coal C and waste plastic W2 in the coke oven 30. Therefore, the waste plastic W1 is charged through the charging port 31 after a predetermined time has elapsed since the carbonization of the coal C in the coke oven 30 began. Vaporized materials such as combustible gas, tar, and diesel fuel generated by the dry distillation (thermal decomposition) of the coal C and waste plastic W are recovered as COG via the riser 32 .

[0029] A method for calculating the airflow velocity in a wind separator, which can be applied to an embodiment of the present invention, will be described below. ｆ (Pa) is the resistance coefficient c Ｄ , gas density ρ ｆ (kg / m ３) and gas flow velocity v (m / s), it is expressed by the following formula (1): Ｄ is expressed by the following equation (2) using the particle Reynolds number Re, and the particle Reynolds number Re is ｆ (kg / m ３ ), gas flow velocity v (m / s), gas viscosity μ (Pa·s), and characteristic length d (mm), which is the thickness of the waste plastic, are expressed by the following equation (3).

[0030]

[0031] From the measurement results of the temperature, flow rate, and composition of the gas in the riser 32 of the coke oven 30, the resistance coefficient c Ｄ is calculated, and then the drag force r is calculated using equation (1). ｆ can be calculated. A measurement hole was installed in the riser pipe 32, and an anemometer such as a Pitot tube was inserted through the measurement hole to measure the gas flow rate. The gas temperature (air temperature) was measured by installing a thermocouple in combination with the Pitot tube. Regarding the gas components, the gas was sucked from the Pitot tube after the anemometer measurement was completed and sampled in a gas bag, and the components were quantified using a gas chromatograph. The measurement position was the center of the pipe. In this way, the drag force r acting on the suspended matter in the riser pipe 32 of the coke oven 30 was calculated. ｆ Once this has been calculated, the values ​​in air at room temperature (20°C) can be substituted into equations (1) to (3) to obtain the same drag force r ｆ In the above example, the rotation speed of the suction blower 13 is set so that this gas flow velocity v (m / s) is obtained at the upper position P of the sorting column 12 of the air sorting device 10. This allows waste plastics that are unlikely to rise in the uprising pipe 32 in the coke oven 30 even without being agglomerated to be separated as heavy waste W1 in the air sorting device 10.

[0032] In one embodiment of the present invention as described above, waste plastics are pre-sorted by air, and the waste plastics separated as heavy fraction W1 are charged into the coke oven 30 without being agglomerated. Therefore, agglomeration by the extruder 20 is performed only on the waste plastics separated as light fraction W2 by air sorting. This reduces the amount of waste plastics to be agglomerated before charging into the coke oven, allowing for an increased throughput of waste plastics without being restricted by the throughput of the agglomeration process. More specifically, the throughput of waste plastics is less likely to be restricted by the processing speed of the extruder 20. Meanwhile, because the waste plastics separated as light fraction W2 are agglomerated, the impact of waste plastic scattering within the coke oven 30 is reduced. Furthermore, by setting the airflow velocity during air sorting as described above, it is possible to more reliably prevent untreated waste plastics W from entering the gas recovery processing path.

[0033] In other embodiments, various types of wind separators can be used in addition to the wind separator 10 illustrated as one embodiment. For example, the wind separator is not limited to one having a vertical separator column 12 as in the above example, but may be one that separates heavy materials from light materials using horizontal or oblique airflow. As described above, the drag force r in the riser pipe 32 of the coke oven 30 ｆ If we calculate the drag force r calculated according to the specifications of the wind sorting device, ｆ Wind sorting can be performed by setting conditions equivalent to the above.

[0034] The results of an experiment conducted to verify the effectiveness of the embodiment of the present invention described above are described below. In the experiment, crushed waste plastics collected as municipal waste were subjected to air sorting using a suction-type air sorter MHV-215 manufactured by Harashima Electric Industry Co., Ltd., and the thickness of the waste plastics separated as heavy materials was measured. Vernier calipers were used to measure the thickness of each sample, and the average value was used. Furthermore, the scattering state of waste plastics with the measured thickness inside a coke oven was analyzed using a simulation.

[0035] Table 1 shows the calculation conditions and results of the airflow velocity in the air separator, i.e., the measurement results of the gas temperature, flow velocity and components in the riser pipe of the coke oven, and the results calculated from these conditions using the above formulas (1) to (3). Note that the characteristic length d in formula (3) was set to 1 mm. The calculated drag force r ｆ The gas flow velocity v obtained in air at room temperature (20°C) was 5.0 m / s.

[0036]

[0037] Fig. 11 is a graph showing the recovery rate for each flow velocity in the wind sorting experiment. The wind sorting experiment was performed by setting the suction blower rotation speed so that the flow velocity at the top of the sorting column of the wind sorting machine was 4.0 m / s, 5.0 m / s, and 6.5 m / s. The experiment found a correlation between the flow velocity and the proportion of waste plastics that fell and were separated as heavy materials (recovery rate). The recovery rate (= weight of falling / weight of input) at a flow velocity of 5.0 m / s calculated above was 37%. In other words, in this experiment, if the flow velocity setting of 5.0 m / s was appropriate, 37% of the waste plastics would be separated and ready to be input into a coke oven without undergoing the agglomeration process.

[0038] 12 is a graph showing the results of measuring the thickness of waste plastics separated by air sorting in the example. The graph shows the thickness distribution of the entire waste plastics fed into the air sorter, the waste plastics separated as light fraction, and the waste plastics separated as heavy fraction, as a weight ratio relative to the input amount. The thickness distribution of the waste plastics separated as heavy fraction is clearly different from that of the entire waste plastics fed into the air sorter and the light fraction, and shows a distribution with a median thickness of 2 mm, which is thicker than the overall distribution.

[0039] Furthermore, in the above measurement results, the minimum thickness of the heavy waste plastics was 0.2 mm. Therefore, if waste plastics with a thickness of 0.2 mm are scattered in the coke oven and do not rise to the riser pipe, the flow velocity setting of 5.0 m / s set in the air separator in the above experiment is appropriate, and it means that waste plastics that are unlikely to rise in the riser pipe in the coke oven can be properly separated without going through the agglomeration process.

[0040] Figure 13 shows the results of a simulation of the scattering state inside a coke oven. In the simulation, the flow state of the gas flow inside the coke oven was first calculated, and then the scattering trajectories of plastic particles of a given size were calculated based on that flow field. The plastic particles were assumed to be spherical, and the scattering trajectories were calculated using three diameters: 0.1 mm, 0.2 mm, and 1 mm. The results showed that when the diameter of the plastic particles was 0.1 mm, almost all particles scattered and rose up the riser pipe, but when the diameters were 0.2 mm and 1 mm, almost none of the particles scattered, and therefore none entered the riser pipe.

[0041] From the above simulation results, it was considered that waste plastics with a thickness of 0.2 mm or more are unlikely to rise in the riser pipe inside the coke oven without undergoing the agglomeration process. Therefore, in the above experiment, it was found that waste plastics that do not require agglomeration can be properly separated by setting the flow velocity in the wind separator to 5.0 m / s. In the above example of waste plastics separated and recovered as general waste, wind separation eliminates the need for the agglomeration process for 37% of the total, which means that it is highly effective in increasing the amount of waste plastics that can be processed without being restricted by the amount of waste plastic that can be processed in the agglomeration process.

[0042] As described in the embodiment of the present invention, the airflow velocity in the airflow separator is calculated according to the specifications of the coke oven and the airflow separator, and is therefore not limited to the numerical values ​​in the above example. Furthermore, the thickness of the waste plastics separated as heavy materials also varies depending on factors such as the airflow velocity, and is therefore not limited to the numerical values ​​in the above example. For example, if the gas flow velocity in the coke oven is low, thinner plastic particles are less likely to scatter, so waste plastics thinner than 0.2 mm may be separated as heavy materials by setting the airflow velocity in the airflow separator to a lower value.

[0043] 1, 2, 3, 4... processing equipment, 10... wind sorting device, 11... feeder, 12... sorting column, 13... suction blower, 14... cyclone chamber, 20... extruder, 30... coke oven, 31... charging port, 32... riser pipe, 40... coal blender, W... waste plastic, W1... heavy materials, W2... light materials, C... coal, SP... furnace space.

Claims

1. A waste plastic treatment facility comprising: a wind sorting device to which waste plastics are supplied; a means for agglomerating the waste plastics separated as light fractions in the wind sorting device; and a coke oven into which the waste plastics separated as heavy fractions in the wind sorting device and the agglomerated waste plastics are charged and which thermally decomposes the waste plastics.

2. The waste plastic processing equipment according to claim 1, wherein the coke oven carbonizes coal and thermally decomposes the waste plastic, and the waste plastic separated as the heavy material and the agglomerated waste plastic are charged into a furnace space formed above the coal during the carbonization of the coal.

3. A waste plastic processing facility as described in claim 1, wherein the waste plastic separated as heavy materials and the agglomerated waste plastic are charged into the furnace space including the furnace bottom of the coke oven.

4. The waste plastic processing equipment according to claim 1, further comprising a means for carbonizing coal and thermally decomposing the waste plastic, and mixing the waste plastic separated as heavy materials and the agglomerated waste plastic into the coal, and the coal mixed with the waste plastic is charged into the coke oven.

5. The waste plastic processing equipment of claim 1, further comprising a means for carbonizing coal and thermally decomposing the waste plastics, and mixing at least a portion of at least the waste plastics separated as heavy substances and the agglomerated waste plastics into the coal, wherein the coal mixed with at least a portion of the waste plastics separated as heavy substances and the agglomerated waste plastics is charged into the coke oven, and the waste plastics separated as heavy substances and the agglomerated waste plastics that have not been mixed into the coal are charged into a furnace space formed above the coal during the carbonization of the coal mixed with at least a portion of the waste plastics separated as heavy substances and the agglomerated waste plastics.

6. A waste plastic processing facility according to any one of claims 1 to 5, wherein the wind sorting device has a vertical sorting column.

7. A waste plastic processing facility according to any one of claims 1 to 5, wherein the means for agglomerating the waste plastic includes an extrusion molding machine.

8. A method for treating waste plastics, comprising: a step of separating waste plastics into heavy fraction and light fraction by wind sorting; a step of agglomerating the waste plastics separated as the light fraction; and a step of loading the waste plastics separated as the heavy fraction and the agglomerated waste plastics into a coke oven and pyrolyzing the waste plastics in the coke oven.

9. A method for treating waste plastics as described in claim 8, wherein the coke oven carbonizes coal and thermally decomposes the waste plastics charged into the coke oven, and the waste plastics separated as heavy materials and the agglomerated waste plastics are charged into a furnace space formed above the coal during the carbonization of the coal.

10. A method for treating waste plastics as described in claim 8, wherein the waste plastics separated as heavy materials and the agglomerated waste plastics are charged into a furnace space including the furnace bottom of the coke oven.

11. The method for treating waste plastics as described in claim 8, further comprising the steps of carbonizing coal and thermally decomposing the waste plastics charged into the coke oven, mixing the waste plastics separated as heavy materials and the agglomerated waste plastics into the coal, and charging the coal with the mixed waste plastics into the coke oven.

12. The method for treating waste plastics as described in claim 8, further comprising the steps of: carbonizing coal in the coke oven and thermally decomposing the waste plastics charged into the coke oven; mixing at least a portion of at least one of the waste plastics separated as heavy substances and the agglomerated waste plastics into the coal; charging the coal mixed with at least a portion of at least one of the waste plastics separated as heavy substances and the agglomerated waste plastics into the coke oven; and charging the waste plastics separated as heavy substances and the agglomerated waste plastics that have not been mixed into the coal into a furnace space formed above the coal during carbonization of the coal mixed with at least a portion of the waste plastics separated as heavy substances and the agglomerated waste plastics.

13. A method for treating waste plastics as described in any one of claims 8 to 12, wherein the coke oven has an ascent pipe through which gas inside the oven is discharged, and further comprising the steps of: calculating the drag force acting on floating matter in the ascent pipe based on the measurement results of the temperature, flow velocity and composition of the gas in the ascent pipe; and setting the air flow velocity in the wind sorting so that the waste plastics are subjected to the same drag force as in the ascent pipe.

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