PET flake cleaning equipment and PET flake cleaning method

Abstract

The purpose of the present disclosure is to provide a PET flake cleaning apparatus and a PET flake cleaning method, capable of obtaining sufficiently cleaned recycled PET flakes when PET flakes obtained from commercial PET bottles are included, and even when only PET flakes obtained from commercial PET bottles are included. A PET flake cleaning apparatus 100 according to the present disclosure comprises: a batch cleaning tank 6 that has a first input part 1 for inputting a cleaning solution and crushed PET flakes as cleaning targets 50, a first container 2, a first stirrer 3, a first discharge port 4, and a tool 5 for opening / closing the first discharge port; and a continuous cleaning tank 12 that is installed downstream of the batch cleaning tank and has a supply unit 7 for supplying, per unit time, a predetermined amount of cleaning targets cleaned in the batch cleaning tank, a second input part 8 for inputting a cleaning solution and cleaning targets, a second discharge port 9, a cleaning flow path 10 connecting the second input part and the second discharge port, and a second stirrer 11.

Description

[Technical field]

[0001] The present disclosure relates to a cleaning device and a cleaning method for PET flakes obtained from recycled used plastic bottles. [Background technology]

[0002] Plastic bottles, such as plastic containers (PET bottles) made of polyethylene terephthalate (PET), are widely used to store beverages, food, etc. In recent years, recycled products such as recycled plastic bottles and recycled fibers have been produced from collected used plastic bottles.

[0003] The collected used plastic bottles include PET bottles that are disposed of separately from households and collected by municipalities (called municipal PET bottles; see Non-Patent Document 1, for example), as well as PET bottles that are disposed of and collected from vending machines, offices, supermarkets, convenience stores, railway companies, public facilities, etc. (called commercial PET bottles; see Non-Patent Document 2, for example). In principle, municipalities separate and collect PET bottles disposed of from households in accordance with the Containers and Packaging Recycling Law, but commercial PET bottles are recycled at the business's own responsibility.

[0004] In order to reuse waste PET such as recovered used plastic bottles as a resource, there is a technology related to a washing method and washing device for washing cut and crushed PET flakes (see, for example, Patent Document 1). Patent Document 1 discloses a washing method for recycled PET flakes, which is characterized by comprising a separation washing process in which the PET flakes fed are stirred in hot washing water to give them a mechanical kneading action, a rinsing process in which the PET flakes that have undergone the separation washing process are pulled out of the hot washing water and rinsed by blowing water to give them a mechanical beating action, and a draining and drying process in which wind is blown onto the PET flakes that have undergone the rinsing process to drain and dry them. Here, the separation washing process discloses a mode in which the PET flakes are mechanically kneaded in a plurality of washing tanks that are partitioned by partition plates so that the lower parts are connected to each other. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-320932 A [Non-patent literature]

[0006] [Non-Patent Document 1] URL;https: / / www.petbottle-rec.gr.jp / more / sort.html [Non-Patent Document 2] URL;https: / / www.petbottle-rec.gr.jp / more / about.html Summary of the Invention [Problem to be solved by the invention]

[0007] In order to reuse used plastic bottles, it is necessary to thoroughly remove foreign matter. Since municipal PET bottles are used plastic bottles that are separated and disposed of from households, many of them are lightly soiled, and it can be said that clean PET flakes can be easily obtained by the cleaning method disclosed in Patent Document 1. However, since commercial PET bottles are disposed of from a wide variety of facilities and collected via a wide variety of routes, the proportion of heavily soiled PET bottles is higher than that of municipal PET bottles. Therefore, in order to obtain regenerated PET flakes (recycled PET flakes) from commercial PET bottles, the cleaning method for PET flakes applied to municipal PET bottles is insufficient.

[0008] Therefore, an object of the present disclosure is to provide a PET flake washing device and a PET flake washing method that can obtain sufficiently washed recycled PET flakes, not only from PET flakes obtained from municipal PET bottles, but also from PET flakes obtained from commercial PET bottles, or even from only PET flakes obtained from commercial PET bottles. [Means for solving the problem]

[0009] As a result of extensive research into solving the above problems, the inventors discovered that the above problems could be solved by combining different washing methods in which PET flakes are first washed in a batch-type washing tank and then washed again in a continuous washing tank, thereby completing the present invention. That is, the PET flake cleaning apparatus of the present invention is characterized by comprising a batch type cleaning tank having a first input section for inputting alkali as a cleaning liquid and crushed PET flakes as an object to be cleaned, a first container for storing the cleaning liquid and the object to be cleaned input from the first input section, a first agitator for agitating the cleaning liquid and the object to be cleaned in the first container, a first outlet for discharging the cleaning liquid and the object to be cleaned in the first container, and an opening and closing device for the first outlet, a supply device installed downstream of the batch type cleaning tank and supplying the object to be cleaned cleaned in the batch type cleaning tank at a predetermined amount per unit time, a second input section into which the cleaning liquid and the object to be cleaned supplied from the supply device are input, a second outlet for discharging the input object to be cleaned and the cleaning liquid, a cleaning flow path connecting the second input section and the second outlet, and a second agitator for agitating the object to be cleaned and the cleaning liquid in the cleaning flow path.

[0010] In the PET flake washing device according to the present invention, a plurality of the batch-type washing tanks are installed in parallel, and a discharge tank is provided for temporarily storing the washing liquid and objects to be washed discharged from each first outlet, and the capacity of the discharge tank is preferably larger than the largest capacity of the plurality of batch-type washing tanks. The objects to be washed discharged from the batch-type washing tanks can be easily supplied at a predetermined amount per unit time and connected to the continuous tank.

[0011] In the PET flake washing apparatus according to the present invention, the supplying device is preferably a turbo washer that is installed downstream of the unloading tank and scrubs the objects washed in the batch-type washing tank. Since the flakes washed in the batch-type washing tank have floating dirt, the washing property can be improved by washing them by scrubbing. Furthermore, in the downstream process, it becomes easier to switch the washing liquid to that of the continuous washing tank.

[0012] In the PET flake washing device according to the present invention, it is preferable that a first dehydrator is provided between the extraction tank and the turbo washer, a receiving tank is provided downstream of the continuous washing tank, a second dehydrator is provided downstream of the receiving tank, and the first dehydrator has a lower dehydration capacity than the second dehydrator. This reduces the amount of washing liquid from the batch washing tank carried over to the continuous washing tank, and improves the washing performance in the turbo washer. In addition, the washing liquid from the continuous washing tank can be reliably removed, and the load of the downstream rinsing process can be reduced. Furthermore, since the first dehydrator has a lower dehydration capacity than the second dehydrator, the washing performance in the turbo washer can be improved and the overall washing time can be shortened.

[0013] In the PET flake washing device according to the present invention, it is preferable that the washing liquid fed into the first input section circulates through a first circulation path that carries the washing liquid separated by the first dehydrator, and the washing liquid fed into the second input section circulates through a second circulation path that carries the washing liquid separated by the second dehydrator. By making the first circulation path and the second circulation path separate paths, the cleanliness of the washing liquid in the second circulation path can be improved. This also makes rinsing easier.

[0014] In the PET flake washing device according to the present invention, the continuous washing tank has n cylindrical containers (n is an integer of 2 or more) arranged in parallel, a first cylindrical container has the second input section provided in the upper side wall or top surface section and has a liquid outlet port in the lower side wall, the nth cylindrical container has a liquid inlet port in the upper side wall connected via a relay flow path to a liquid outlet port provided in the lower side wall of an adjacent cylindrical container, and has a liquid outlet port in the lower side wall, the second input section, the interior of the first cylindrical container, the liquid outlet port of the first cylindrical container, The flow path connecting the relay flow path, the liquid inlet of the nth cylindrical container, the inside of the nth cylindrical container, the liquid outlet of the nth cylindrical container, and the second outlet forms the cleaning flow path, and each cylindrical container has an agitating blade fixed to the agitating shaft as the second agitator, the agitating blade has an upward flow blade and a downward flow blade, and the upward flow blade 24a and the downward flow blade 24b are alternately arranged along the axial direction of the agitating shaft, and each cylindrical container preferably has a frame protruding in an annular shape from the inner wall of the container at a position above the liquid outlet. Even in a continuous cleaning tank, it is possible to prevent a part of the PET flakes from being prematurely discharged from the continuous cleaning tank due to insufficient cleaning.

[0015] The PET flake washing method of the present invention is characterized by comprising a first washing step in which crushed PET flakes as the object to be washed are stored together with an alkali as a washing liquid in a batch-type washing tank and washed while being stirred for a predetermined time, and a second washing step in which the PET flakes washed in the batch-type washing tank are transferred to a continuous washing tank at a predetermined amount per unit time and washed. Effect of the Invention

[0016] According to the present disclosure, it is possible to provide a PET flake washing device and a PET flake washing method that can obtain sufficiently washed recycled PET flakes not only from PET flakes obtained from municipal PET bottles, but also from cases where PET flakes obtained from commercial PET bottles are included, or even from only PET flakes obtained from commercial PET bottles. [Brief description of the drawings]

[0017] [Figure 1] This is a process diagram of how recycled PET flakes are made from collected PET bottles. [Diagram 2] 1 is a schematic diagram of a PET flake washing device according to an embodiment of the present invention. [Diagram 3] FIG. 1 is a schematic diagram of a batch cleaning apparatus. [Figure 4] FIG. 2 is a schematic diagram of the withdrawal tank. [Diagram 5] FIG. 2 is a schematic diagram of a first dehydrator. [Figure 6] FIG. 1 is a schematic diagram of a turbo washer. [Figure 7] FIG. 2 is a schematic diagram of a continuous side cleaning device. [Figure 8] FIG. [Figure 9] FIG. 4 is a schematic diagram of a second dehydrator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the present invention will be described in detail with reference to the embodiments, but the present invention is not limited to these descriptions. Various modifications of the embodiments may be made as long as the effects of the present invention are achieved.

[0019] <Overall flow of the manufacturing process for recycled PET flakes> (1) Flake cleaning pre-process 45 The manufacturing process of recycled PET flakes will be described with reference to FIG. 1. Municipal PET bottles or business PET bottles are prepared as collected PET bottles. In both cases, multiple PET bottles are bundled together to facilitate handling during transportation. First, municipal PET bottles or business PET bottles are fed into the line (feeding process 30). Municipal PET bottles and business PET bottles may be fed without distinguishing between them. Next, the bundled PET bottles fed into the line are separated into individual bottles (unpacking process 31). Since municipal PET bottles or business PET bottles contain, in addition to PET bottles, small foreign objects, metal (cans), leftover drinks, colored bottles, bottles made of different materials (e.g., polyvinyl chloride bottles), labels, and other contaminants, only PET bottles are selected by sorting (sorting process 32). Next, the PET bottles are finely crushed using a PET bottle crusher to obtain pre-washed flakes (crushing process 33). Next, the caps are separated (cap separation process 34). The above steps constitute the flake pre-washing process 45. The sorting process may be divided into several steps, and the order of steps may be changed within the flake pre-washing process. For example, label removal may be performed after the crushing process 33.

[0020] (2) Flake washing process 46 The flake washing process 46 includes batch washing and continuous washing. That is, the PET flake washing method according to this embodiment has a first washing process in which crushed PET flakes as objects to be washed are stored together with an alkali as a washing liquid in a batch washing tank and washed while stirring for a predetermined time, and a second washing process in which the PET flakes washed in the batch washing tank are transferred to a continuous washing tank at a predetermined amount per unit time and washed.

[0021] [First cleaning process] The flakes before washing are first put into a batch type washing device (batch type washing step 35). Next, a dehydration step is performed to separate the washing liquid from the PET flakes washed in the batch type washing step 35 (first dehydration step 36). The washing liquid used in the batch type washing step 35 and the first dehydration step 36 is preferably circulated while removing foreign matter and stabilizing the alkali concentration (batch type washing liquid adjustment step 37). The washing liquid and the object to be washed are put in so that the slurry rate is 5 to 25 mass %. The washing liquid is, for example, an alkali with a concentration of 1 to 10%. The washing liquid is, for example, heated to 70 to 98°C. The washing time of the batch type washing is, for example, 10 to 100 minutes. The alkali is preferably sodium hydroxide, and may contain, as additives, defoamers, surfactants, etc. within a range that does not cause problems as a food container.

[0022] [Second cleaning process] Since the dehydrated PET flakes still have the cleaning solution attached and dirt floating on them, the PET flakes can be rubbed while being transported to improve their cleanability before being sent to the cleaning device in the next process, the continuous cleaning process 39 (friction cleaning process 38). For recycled PET flakes from municipal PET bottles, purified recycled PET flakes can be obtained by going through batch cleaning. For recycled PET flakes from commercial PET bottles, continuous cleaning is performed to obtain safe and reliably purified recycled PET flakes. The PET flakes that have gone through the friction cleaning process 38 are fed into the continuous cleaning device. As the PET flakes pass through the cleaning flow path filled with cleaning solution maintained at specified conditions, they are washed again (continuous cleaning process 39). At this time, in order to prevent some of the PET flakes from passing through the washing flow path in a shorter time than other PET flakes and to ensure that the entire PET flakes are washed to the same extent, it is preferable to provide a means for preventing uniform flow, such as providing a change in the flow direction in the washing flow path to generate agitation in the cross-sectional direction of the flow path, providing a change in the cross-sectional area of ​​the flow path to change the flow speed and generate agitation in the forward and backward directions along the flow direction, and further providing a stirring blade or stirring plate to generate turbulence. After re-washing, the washing liquid is dehydrated (second dehydration step 40). It is preferable to circulate the washing liquid used in the continuous washing step 39 and the second dehydration step 40 while removing foreign matter and stabilizing the alkali concentration (continuous washing liquid adjustment step 41). The washing liquid and the object to be washed are introduced so that the slurry rate is 5 to 25 mass %. The washing liquid is, for example, an alkali with a concentration of 1 to 10%. The washing liquid is heated to, for example, 70 to 98°C. The washing time of the continuous washing is, for example, 10 to 100 minutes. The alkali is preferably sodium hydroxide, and may contain additives such as antifoaming agents and surfactants within the range that does not cause problems for food containers. The conditions of the cleaning solution and the object to be cleaned are preferably the same in the first cleaning step and the second cleaning step, except for the cleaning time.

[0023] (3) Flake washing process 47 After washing through the second dehydration step, the washed flakes are rinsed (rinsing step 42) to remove the cleaning liquid, dried (drying step 43), and recycled PET flakes are obtained (product flake step 44).

[0024] <PET Flake Washing Device> Next, with reference to FIGS. 2 to 9, the PET flake washing device 100 according to the present embodiment used in the flake washing step 46 will be described. The PET flake washing device 100 according to the present embodiment includes a first input unit 1 for inputting an alkali as a cleaning liquid and crushed PET flakes as an object to be cleaned, a first container 2 for storing the cleaning liquid and the object to be cleaned input from the first input unit 1, a first stirrer 3 for stirring the cleaning liquid and the object to be cleaned in the first container 2, a first discharge port 4 for discharging the cleaning liquid and the object to be cleaned in the first container 1, and a shutter 5 for the first discharge port 4, and has a batch-type washing tank 6, a supply device 7 installed on the downstream side of the batch-type washing tank 6 for supplying the object to be cleaned washed in the batch-type washing tank 6 at a predetermined amount per unit time, a second input unit 8 into which the cleaning liquid and the object to be cleaned supplied from the supply device are input, a second discharge port 9 for discharging the input object to be cleaned and the cleaning liquid, a cleaning flow path 10 connecting the second input unit 8 and the second discharge port 9, and a second stirrer 11 for stirring the object to be cleaned and the cleaning liquid in the cleaning flow path 10, and includes a continuous-type washing tank 12.

[0025] (1) Batch-type washing system [Batch-type washing tank] As shown in FIG. 2 and FIG. 3, the first input section 1 for inputting the cleaning object 50, PET flakes before cleaning, and the cleaning liquid is provided at the top of the first container 2 of the batch-type cleaning tank 6. The first agitator 3 is rotated by a motor to agitate the cleaning liquid and the cleaning object stored in the first container 2. The first outlet 4 for discharging the cleaning liquid and the cleaning object that has been agitated and washed is provided at the bottom of the first container 1, and an opening and closing device 5 for the first outlet 4 is provided below it. After the cleaning object is washed for a predetermined time with a cleaning liquid under predetermined conditions, the opening and closing device 5 is opened, and the cleaning liquid and the cleaning object 52 are discharged to the subsequent process. The opening and closing device 5 is preferably a slider type that opens and closes by sliding a plate. Clogging of the cleaning object 52 is prevented. It is preferable that a plurality of batch-type cleaning tanks 6 are installed in parallel, such as batch-type cleaning tanks 6a, 6b, and 6c shown in FIG. 2. The first containers of the batch-type cleaning tanks 6a to 6c may have different capacities, but preferably have the same capacity. The batch-type cleaning tank 6 preferably has a heater (for example, a steam heating type) not shown.

[0026] [Extraction tank] As shown in FIG. 2 and FIG. 4, the unloading tank 13 is installed below the batch-type cleaning tank 6 and temporarily stores the cleaning liquid and the object 52 to be cleaned discharged from the first discharge port 4. When a plurality of batch-type cleaning tanks 6a, 6b, and 6c are installed in parallel, the cleaning liquid and the object 52 to be cleaned discharged from each first discharge port 4 are stored in the unloading tank 13. A screw conveyor 51 is installed at the bottom of the unloading tank 13, and the screw conveyor 51 is arranged from the side wall of the bottom of the unloading tank 13 to the inside of a connected cylinder 54. The screw conveyor 51 rotated by a motor supplies the cleaning liquid and the object 53 to the subsequent process at a constant amount per unit time. By increasing the length 55 of the cylinder 54, the actual internal volume excluding the volume of the screw conveyor 51 in the cylinder 54 can be increased, so that the constant supply of the cleaning liquid and the object 53 to be cleaned can be stabilized. For example, the actual internal volume of the cylinder 54 is 2 to 10% of the volume of the first container 2. When the capacities of the batch-type cleaning tanks are different from each other, the capacity of the extraction tank 13 is preferably larger than the largest capacity. The cleaning liquid and the object 52 to be cleaned can be temporarily stored reliably. When the batch-type cleaning tank 6 is used to remove the object 52 to be cleaned, clogging is likely to occur if the object 52 is discharged at a low flow rate. Therefore, the slider-type opening and closing device 5 is used to prevent clogging and to increase the discharge efficiency. However, it is desired that the dehydration in the first dehydrator and the cleaning in the continuous cleaning tank in the subsequent process are performed at a constant speed, and if the object 52 to be cleaned is discharged from the batch-type cleaning tank 6 all at once, the processing becomes difficult. Therefore, the extraction tank 13 adjusts the feed speed of the object and the cleaning liquid in a direction to reduce the fluctuation in the speed, and adapts it to the processing speed of the subsequent process.

[0027] [1st dehydrator] As shown in FIG. 2 and FIG. 5, the first dehydrator 14 is disposed between the extraction tank 13 and the supply device 7, for example, a turbo washer. In the first dehydrator 14, a cylindrical mesh-like drum 56 having a plurality of openings in a side wall is laid horizontally and rotated by a motor. The cleaning liquid and the object 53 to be cleaned are supplied into the drum 56 from one end of the cylinder of the drum 56. When the drum 56 rotates, the cleaning liquid moves out of the drum 56 through the opening, and the object 53 to be cleaned moves along the direction of the rotation axis of the drum 56 and reaches the other end of the cylinder of the drum 56. The separated cleaning liquid is transferred to the first circulation path 17 by the first dehydrator 14, and the dehydrated object 58 to be cleaned is discharged to a subsequent process.

[0028] [First circulation route] As shown in Fig. 2, the cleaning liquid introduced into the first input section 1 together with the unwashed PET flakes 50 (objects to be cleaned 50) circulates through a first circulation path 17 that carries the cleaning liquid separated by the first dehydrator 14. A vibrating sieve 69a is installed in the first circulation path 17, which sieves the circulating cleaning liquid to remove sieve residue 70a. The cleaning liquid that passes through the vibrating sieve 69a is purified and is introduced back into the first input section 1 together with the unwashed PET flakes 50.

[0029] (2) Continuous cleaning system [Feeding device] As shown in FIG. 2 and FIG. 6, the supply device 7 is installed downstream of the batch type washing tank 6 and supplies the object to be washed in the batch type washing tank 6 at a predetermined amount per unit time. The supply device 7 is installed downstream of the extraction tank 13, preferably downstream of the first dehydrator 14, and is preferably a turbo washer that washes the object to be washed in the batch type washing tank 6 while rubbing it. Since the flakes washed in the batch type washing tank have dirt floating on them, the washability can be improved by performing rubbing washing (kneading washing). In addition, in the process after the supply device, it becomes easy to switch the washing liquid to that of the continuous type washing tank. The object to be washed 58 dehydrated by the first dehydrator 14 is fed into the inlet of the turbo washer, which is the supply device 7, as shown in FIG. 6. The turbo washer has a screw-type stirring rod with multiple blades attached to a rotating shaft 57, and the stirring rod is rotated by a motor. The stirring rod is tilted at an angle. As the stirring rod rotates, it rubs the PET flakes, which are the objects to be cleaned, and sends them upward. Here, the turbo washer has a cleaning liquid supply section that pours cleaning liquid onto the outlet side of the PET flakes, and the cleaning liquid is sent directly to the continuous cleaning tank together with the objects to be cleaned 59 that have been cleaned by the turbo washer. The cleaning liquid supplied by the cleaning liquid supply section of the turbo washer is the cleaning liquid circulating through the second circulation path 18, and the cleaning liquid circulating through the second circulation path 18 is used in the process after the turbo washer. At this stage, the slurry concentration is adjusted to a level suitable for cleaning in the continuous cleaning tank. The direction of movement of the objects to be cleaned is indicated by an arrow in Figure 6.

[0030] [Continuous cleaning tank] As shown in FIG. 2 and FIG. 7, the continuous cleaning tank 12 has a second input part 8 into which the cleaning liquid and the object to be cleaned 59 supplied from the supply device 7 are input, a second outlet 9 for discharging the input object to be cleaned 59 and the cleaning liquid, a cleaning flow path 10 connecting the second input part 8 and the second outlet 9, and a second agitator 11 for stirring the object to be cleaned and the cleaning liquid in the cleaning flow path 10. The second input part 8 is provided in the upper part of the cylindrical container 19. The second outlet 9 is preferably provided in the upper part or lower part of the cylindrical container 19. In a configuration in which there is one cylindrical container 19, the second outlet 9 is preferably provided in the lower part of the cylindrical container 19. In a configuration in which two or more cylindrical containers 19 are arranged in parallel, the second outlet 9 is preferably provided in the upper part of the cylindrical container 19. The cleaning flow path 10 is a path connecting the second input part 8 and the second outlet 9, and the cleaning flow path 10 is indicated by an arrow 10 in FIG. 7. The second agitator 11 is provided to agitate the object to be cleaned and the cleaning liquid in the cleaning flow path 10, and has, for example, an agitator shaft 25 and an agitator blade 24. When the object to be cleaned 59 passes through the cleaning flow path 10, it is agitated together with the cleaning liquid, and cleaning is performed at least during the time the object to be cleaned passes through the cleaning flow path 10. The second agitator 11 prevents some of the object to be cleaned 59 from passing through the cleaning flow path 10 in a shorter time than the others.

[0031] The continuous cleaning tank 12 in which cylindrical containers 19 are arranged in parallel, as shown below, allows the objects 59 to pass through the cleaning flow path 10 for a longer period of time, and further prevents some of the objects 59 from passing through the cleaning flow path 10 in a shorter time than others. This is advantageous in improving the cleaning properties of PET flakes obtained from industrial PET bottles. That is, the continuous cleaning tank 12 has n cylindrical containers 19 (n is an integer of 2 or more; in FIG. 7, n=2) arranged in parallel, the first cylindrical container 19 has a second input section 8 provided in the upper part of the side wall or the top surface, and a liquid outlet 20 in the lower part of the side wall, the nth cylindrical container has a liquid inlet 22 in the upper part of the side wall which is connected via a relay flow path 21 to the liquid outlet 20 provided in the lower part of the side wall of the adjacent cylindrical container (which is the first cylindrical container in this case), and has a liquid outlet 23 in the lower part of the side wall, and it is preferable that the flow path connecting the second input section 8, the interior of the first cylindrical container 19, the liquid outlet 20 of the first cylindrical container, the relay flow path 21, the liquid inlet 22 of the nth cylindrical container, the interior of the nth cylindrical container 19, the liquid outlet 23 of the nth cylindrical container, and the second outlet 9 forms the cleaning flow path 10. Each cylindrical vessel 19 has an agitating blade 24 fixed to an agitating shaft 25 as a second agitator 11, and the agitating blade 24 has a blade 24a that generates an upward flow and a blade 24b that generates a downward flow, and it is preferable that the blades 24a that generate the upward flow and the blades 24b that generate the downward flow are alternately arranged along the axial direction of the agitating shaft 25. Each cylindrical vessel 19 preferably has a frame portion 27 that protrudes in an annular shape from the inner wall of the vessel at a position above the liquid outlets 20, 23. Even in a continuous washing tank, it prevents a part of the flakes from being discharged due to insufficient washing. The washing flow path 10 is formed in a zigzag shape by arranging the cylindrical vessels 19 in parallel, providing the second input portion 8 or the liquid intake port 22 at the upper part or top surface of the side wall, and providing the liquid outlets 20, 23 at the lower part of the side wall. As a result, agitation in the cross-sectional direction of the washing flow path 10 is promoted. In addition, by passing through the relay flow path 21, agitation in the front and rear of the flow direction of the washing flow path 10 is promoted. In addition, the second agitator 11 installed in each cylindrical container 19, that is, the agitating blade 24 fixed to the agitating shaft 25 connected to the motor, further agitates the objects to be cleaned and the cleaning liquid.Further, the second agitator 11, in which the blades 24a generating an upward flow and the blades 24b generating a downward flow are alternately arranged along the axial direction of the agitation shaft 25, agitates the object to be cleaned and the cleaning liquid while generating a shear force in the vertical direction of the cylindrical container 19 and in the cross-sectional direction of the agitation shaft 25, improving the cleaning power. Furthermore, the frame part 27 has a structure that protrudes in an annular shape from the inner wall of the cylindrical container 19 at a position above the liquid outlets 20 and 23, so that the object to be cleaned being agitated by the agitation blades 24 does not easily fall to the bottom of the cylindrical container 19, the object to be cleaned that has fallen to the bottom does not easily rise again, and the object to be cleaned easily comes out of the liquid outlet 20. The object to be cleaned is taken out of the liquid outlet 23, and is further sent upward through a flow path on the outside of the side wall of the cylindrical container 19, and is discharged from the second discharge port 9 together with the cleaning liquid as the object to be cleaned 60.

[0032] [Receiving tank] As shown in FIG. 2 and FIG. 8, the receiving tank 15 installed on the downstream side of the continuous cleaning tank 12 has a third input section 62 on the upper side wall or top surface of the tank. The cleaning liquid and the object 60 discharged from the second outlet 9 are input into the third input section 62. The receiving tank 15 has a third agitator 63, which agitates the cleaning liquid and the object 60 inside the tank to continue cleaning. A third outlet 68 is provided at the bottom of the receiving tank 15, and the cleaning liquid and the object 60 discharged from the third outlet 68 are lifted diagonally upward by a screw conveyor 64 connected to a motor. The lifted cleaning liquid and the object 65 are sent to the second dehydrator 16. The receiving tank 15 supplies the cleaning liquid and the object 65 to the second dehydrator 16 while maintaining a constant supply speed. In FIG. 8, the direction of movement of the object is indicated by an arrow.

[0033] [Second dehydrator] As shown in FIG. 2 and FIG. 9, the second dehydrator 16 is disposed downstream of the receiving tank 15. In the second dehydrator 16, a fourth agitator 66 with an agitating blade rotated by a motor is installed horizontally in a cylindrical container. The fourth agitator 66 vigorously rubs the objects to be cleaned in the cylindrical container to remove dirt. As the fourth agitator 66 rotates, the objects to be cleaned move along the axial direction and reach the other end side. At this time, the cleaning liquid and the objects to be cleaned are separated, the cleaning liquid is taken out from the lower part of the cylindrical container laid horizontally, and the objects to be cleaned 67 are taken out from the upper part of the cylindrical container. The separated cleaning liquid is transferred to the second circulation path 18 by the second dehydrator 16, and the dehydrated objects to be cleaned 67 are discharged to a subsequent process. It is preferable that the first dehydrator 14 has a lower dehydration capacity than the second dehydrator 16. Alternatively, it is preferable that the second dehydrator 16 has a higher dehydration capacity than the first dehydrator 14. Since the first dehydrator 14 has a lower dehydration capacity than the second dehydrator 16, the amount of cleaning liquid from the batch-type cleaning tank 6 carried over to the continuous cleaning tank 12 can be reduced and cleaning performance with a turbo washer can be improved. Since the second dehydrator 16 has a higher dehydration capacity than the first dehydrator 14, the cleaning liquid can be reliably removed from the continuous cleaning tank 12 and the load on the downstream rinsing process can be reduced. The dehydrated cleaning target 67 is supplied to the rinsing process 42 in the next process, the post-flake cleaning process 47. In FIG. 9, the direction of movement of the cleaning target is indicated by an arrow.

[0034] [Second circulation route] As shown in FIG. 2, the cleaning liquid fed into the supply device 7 such as a turbo washer circulates through the second circulation path 18, which flows the cleaning liquid separated by the second dehydrator 16. A vibrating sieve 69b is installed in the second circulation path 18, which sieves the circulating cleaning liquid to remove the sieve residue 70b. The cleaning liquid that passes through the vibrating sieve 69b is purified and fed back into the supply device 7. It is also possible to connect the first circulation path and the second circulation path to form a single circulation path. However, in a batch-type cleaning system, since a lot of dirt is attached to the object 50 to be cleaned that is fed, the cleaning liquid is likely to contain a lot of dirt. Therefore, by making the first circulation path and the second circulation path separate paths, the cleanliness of the cleaning liquid in the second circulation path can be improved. This also makes rinsing easier.

[0035] It is preferable to provide a drainage path to prevent overflow at the top of the extraction tank 13 and return the water to the first circulation path. It is preferable to provide drains or drainage paths to prevent overflow at the bottom of the turbo washer, the bottom of the cylindrical container 19 of the continuous washing tank 12, and the bottom and top of the receiving tank 15 and return the water to the second circulation path.

[0036] As used throughout this disclosure, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a composition" includes a plurality of such compositions, as well as a single composition. [Explanation of symbols]

[0037] 1 1st input section 2 1st container 3. First Mixer 4 1st outlet 5 Opening and Closing Devices 6,6a,6b,6c Batch type cleaning tank 7 Feeding device 8 2nd input section 9 2nd outlet 10 Washing channel 11 Second mixer 12 Continuous cleaning tank 13 Extraction tank 14 1st dehydrator 15 Receiving tank 16 2nd dehydrator 17 First Circulation Route 18 Second Circulation Route 19 Cylindrical container 20 Liquid outlet 22 Liquid intake port 23 Liquid outlet 24 Stirring blade 24a Wing that creates an updraft 24b Downdraft-causing wing 25 Stirring shaft 27 Frame 50 Pre-washed PET flakes 51,64 Screw conveyor 52, 53, 58, 59, 60, 65, 67 Cleaning object 54 Cylinder 55 Length of cylinder 56 Drums 57 Rotational Axis 62 3rd input section 63 3rd stirrer 66 4th Mixer 68 3rd outlet 69a,69b Vibrating sieve 70a,70b Sieve residue 100 PET flakes washing equipment

Claims

1. a batch-type cleaning tank having a first input section for inputting an alkali as a cleaning liquid and crushed PET flakes as an object to be cleaned, a first container for storing the cleaning liquid and the object to be cleaned input from the first input section, a first agitator for agitating the cleaning liquid and the object to be cleaned in the first container, a first discharge port for discharging the cleaning liquid and the object to be cleaned in the first container, and an opening and closing device for the first discharge port; a supply device that is installed downstream of the batch-type cleaning tank and supplies the objects to be cleaned in the batch-type cleaning tank at a predetermined amount per unit time; a continuous cleaning tank having a second input section into which the cleaning liquid and the objects to be cleaned supplied from the supply device are input, a second outlet for discharging the input objects to be cleaned and the cleaning liquid, a cleaning flow path connecting the second input section and the second outlet, and a second agitator for agitating the objects to be cleaned and the cleaning liquid in the cleaning flow path; A PET flake washing device comprising:

2. The batch-type cleaning tanks are installed in a plurality of parallel arrangements, and each tank has a discharge tank for temporarily storing the cleaning liquid and the object to be cleaned discharged from the first discharge port, 2. The PET flake washing apparatus according to claim 1, wherein the capacity of the unloading tank is larger than the largest capacity of the plurality of batch type washing tanks.

3. 3. The PET flake washing apparatus according to claim 2, wherein the supplying device is a turbo washer that is installed downstream of the extraction tank and scrubs the objects to be washed in the batch-type washing tank.

4. A first dehydrator is provided between the extraction tank and the turbo washer, A receiving tank is provided downstream of the continuous cleaning tank, A second dehydrator is provided downstream of the receiving tank; and 4. The PET flake washing apparatus according to claim 3, wherein the first dehydrator has a lower dehydration capacity than the second dehydrator.

5. The cleaning liquid input to the first input section circulates through a first circulation path through which the cleaning liquid separated by the first dehydrator flows; 5. The PET flake washing device according to claim 4, wherein the washing liquid fed to the second feed section circulates through a second circulation path that carries the washing liquid separated by the second dehydrator.

6. The continuous cleaning tank has n cylindrical containers (where n is an integer of 2 or more) arranged in parallel, the first cylindrical container has the second input port provided on an upper side wall or a top surface thereof, and has a liquid outlet port on a lower side wall thereof; the nth cylindrical container has a liquid inlet in an upper part of a side wall, the liquid inlet being connected via a relay flow path to a liquid outlet provided in a lower part of the side wall of an adjacent cylindrical container, and has a liquid outlet in a lower part of the side wall; a flow path connecting the second input portion, the interior of the first cylindrical container, the liquid outlet of the first cylindrical container, the relay flow path, the liquid inlet of the nth cylindrical container, the interior of the nth cylindrical container, the liquid outlet of the nth cylindrical container, and the second outlet forms the cleaning flow path; Each cylindrical vessel has an agitating blade fixed to an agitating shaft 25 as the second agitator 11, The stirring blade has a blade 24a which generates an upward flow and a blade 24b which generates a downward flow, The blades generating an upward flow and the blades generating a downward flow are alternately arranged along the axial direction of the stirring shaft, 3. The PET flake washing device according to claim 1, wherein each cylindrical container has a frame portion protruding in an annular shape from an inner wall of the container at a position above the liquid outlet port.

7. A first cleaning process in which crushed PET flakes as objects to be cleaned are stored together with an alkali as a cleaning solution in a batch-type cleaning tank and cleaned while being stirred for a predetermined period of time; a second washing step of transferring the PET flakes washed in the batch-type washing tank to a continuous washing tank at a predetermined amount per unit time and washing the same.

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