Synthetic resin molding material dryer

Abstract

To provide a synthetic resin molding material dryer capable of effectively using thermal energy and drying a synthetic resin molding material in a shorter time in a temperature zone where the physical property of the synthetic resin molding material such as a resin pellet is hardly changed.SOLUTION: A dryer 1 comprises: a drying hopper 2; generation units 8, 7A for generating dry air for drying a synthetic resin molding material in the drying hopper 2; a dry air feed passage L1 for feeding dry air to the drying hopper 2; an exhaust air discharge passage L2 for discharging, from the drying hopper 2, dry air supplied for drying the synthetic resin molding material in the drying hopper 2; and an exhaust air feed passage L7 for feeding a part of exhaust air flowing in the exhaust air flow passage L2 to the drying hopper 2, wherein the drying hopper 2 is configured in such a way that the dry air from the dry air feed passage L1 is introduced into a lower part side, and the exhaust air from the exhaust air feed passage L7 is introduced to an upper part side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a drying device that removes moisture from a synthetic resin molding material, such as a resin pellet. [Background technology]

[0002] Synthetic resin molding materials are generally processed into pellets and then supplied to a resin molding machine such as an injection molding machine. Resin pellets absorb moisture from the air, and if they contain a lot of moisture, they undergo hydrolysis during the melt-kneading process, causing a significant decrease in the quality of the molded product, such as a decrease in the strength and impact resistance of the molded product. In addition, this also causes defects in the appearance of the molded product. Therefore, the resin pellets are supplied to an injection molding machine or the like after the moisture is removed.

[0003] As a means for removing moisture from resin pellets, for example, a drying device has been conventionally known in which high-temperature, low-dew-point dry air is supplied to a drying hopper containing resin pellets and the dry air is brought into contact with the resin pellets in the drying hopper. In the drying device, the resin pellets in the drying hopper are heated by the dry air, which causes the moisture adhering to the surfaces of the resin pellets and the moisture contained inside the resin pellets to evaporate. The evaporated moisture is then carried away by the dry air, thereby removing the moisture from the resin pellets (see, for example, Patent Document 1).

[0004] Fig. 5 shows a schematic configuration of a conventional example of the drying device described above. Dry air is generated by heating low dew point air to a high temperature in a heater 101, and is supplied to a drying hopper 100. Resin pellets are supplied to the drying hopper 100 from a hopper loader 102. The resin pellets in the drying hopper 100 are dried by being heated by the dry air. The dried resin pellets are discharged from the drying hopper 100 by opening an electromagnetic valve 103, and are supplied to a resin molding machine 105 through a transport pipe 104.

[0005] The dry air used to dry the resin pellets in the drying hopper 100 has its temperature lowered by heat absorbed by the resin pellets and its humidity increased by removing moisture from the resin pellets, and is then discharged from the drying hopper 100. The dry air (exhaust air) discharged from the drying hopper 100 has foreign matter contained in the exhaust air removed by the dust collector 107, cooled by the cooler 108, compressed by the blower 109, and cooled again by the cooler 110 before being supplied to the dehumidifier 106. The exhaust air is dehumidified by the dehumidifier 106 to become low dew point air, and is used again as dry air for drying the resin pellets in the drying hopper 100. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Publication number 7-19770 Summary of the Invention [Problem to be solved by the invention]

[0007] The coolers 108, 110 that cool the exhaust air are generally water-cooled coolers. The water-cooled coolers can efficiently cool the exhaust air using cooling water, but the cooling water that recovers the thermal energy contained in the exhaust air as it cools the exhaust air is cooled in a cooling tower. Therefore, although the exhaust air discharged from the drying hopper 100 has a high temperature and thermal energy, conventional drying devices cannot effectively utilize the thermal energy contained in the exhaust air.

[0008] In addition, the higher the temperature of the drying air, the shorter the drying time for drying the resin pellets, and the higher the temperature of the dried resin pellets, so that the dried resin pellets can be efficiently supplied to a resin molding machine such as an injection molding machine at a high temperature. However, as the temperature of the drying air increases, the temperature of the resin pellets also increases accordingly, which makes it easier for the physical properties of the resin pellets to change due to decomposition (hydrolysis, oxidative decomposition, thermal decomposition, etc.) or deterioration. Therefore, if some abnormality occurs in the drying device during the drying of the resin pellets and the resin pellets continue to remain in the drying hopper at a high temperature for a predetermined drying time or longer, the physical properties of the resin pellets may change. On the other hand, there is a problem that if the temperature of the drying air is low, the drying time of the resin pellets becomes long.

[0009] The present disclosure has been made in consideration of the above circumstances, and aims to provide a drying device for synthetic resin molding material that can effectively utilize thermal energy and dry synthetic resin molding material, such as resin pellets, in a shorter time at a temperature range that is less likely to cause changes in the physical properties of the synthetic resin molding material. [Means for solving the problem]

[0010] In order to solve the above problems, the drying device of the present disclosure encompasses as its subject the drying device described in item 1 below.

[0011] Item 1. A drying hopper configured to accommodate a synthetic resin molding material introduced from an upper portion and discharge the synthetic resin material from a lower portion; A generating unit that generates dry air for drying the synthetic resin molding material in the drying hopper; a dry air supply passage for supplying the dry air to the drying hopper; an exhaust air discharge passage for transporting exhaust air discharged from the drying hopper after drying the synthetic resin molding material in the drying hopper; an exhaust air supply passage for supplying a portion of the exhaust air flowing through the exhaust air flow path to the drying hopper; Equipped with The drying hopper is configured so that the dry air from the dry air supply passage is introduced to a lower side thereof, and the exhaust air from the exhaust air supply passage is introduced to an upper side thereof.

[0012] Furthermore, the drying device of the present disclosure encompasses the drying device described in the following item 2 as a preferred embodiment of the drying device described in item 1 above.

[0013] Item 2. The generating unit includes a dehumidifier that generates low dew point air and a first heater that heats the low dew point air to form the dry air; 2. The drying device according to item 1, wherein the exhaust air discharge path is provided with a second heater for heating the exhaust air to be supplied to the drying hopper.

[0014] Furthermore, the drying device of the present disclosure encompasses the drying device described in the following item 3 as a preferred embodiment of the drying device described in items 1 and 2 above.

[0015] Item 3. The drying device according to item 1 or 2, wherein the temperature of the drying air supplied to the drying hopper is 110°C or higher and 140°C or lower. Effect of the Invention

[0016] According to the drying device of the present disclosure, it is possible to effectively utilize thermal energy and to dry synthetic resin molding materials, such as resin pellets, in a shorter time in a temperature range in which changes in the physical properties of the synthetic resin molding materials are unlikely to occur. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic configuration diagram of a drying device according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of the drying hopper. [Diagram 3] FIG. 3 is a schematic configuration diagram of a drying device according to another embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic configuration diagram of a drying device according to another embodiment of the present disclosure. [Diagram 5] FIG. 5 is a schematic diagram of a conventional drying device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present disclosure relates to a drying device that removes moisture from synthetic resin molding materials, which are raw materials, when manufacturing plastic molded products by, for example, injection molding or extrusion molding. Synthetic resin molding materials have hygroscopic properties and absorb moisture from the atmosphere. If the synthetic resin molding material is supplied to a resin molding machine in a state where it contains a lot of moisture, hydrolysis occurs during the melt-kneading process, causing a decrease in the strength and impact resistance of the molded product, and significantly degrading the quality of the molded product. In addition, it also causes defects in the appearance of the molded product. Therefore, it is necessary to remove moisture from the synthetic resin molding material before it is supplied to the resin molding machine. The drying device of the present disclosure is a technology for drying the synthetic resin molding material and removing moisture from the synthetic resin molding material.

[0019] The synthetic resin molding material may be, for example, in the form of a powder, granules, pellets, or the like, but the shape is not particularly limited. In the embodiment described below, the synthetic resin molding material is a resin pellet, but the synthetic resin molding material is not limited to a resin pellet. The synthetic resin molding material is made of a thermoplastic resin. Examples of the thermoplastic resin include, but are not limited to, polyesters such as polyethylene terephthalate, polyethylene, polypropylene, polystyrene, ABS, and polyamide.

[0020] Hereinafter, one embodiment of a drying device according to the present disclosure will be described in detail with reference to the drawings.

[0021] As shown in Fig. 1, the drying device 1 includes a drying hopper 2 that accommodates resin pellets. As shown in Fig. 2, the drying hopper 2 has an accommodation space 22 capable of accommodating resin pellets therein. The resin pellets are dried while being accommodated in the drying hopper 2.

[0022] 1 and 2, an introduction section 20 for resin pellets is provided at the top of the drying hopper 2. For example, a loader hopper 3 is disposed above the drying hopper 2. Undried resin pellets are transported to the loader hopper 3 from a raw material tank (not shown), and the undried resin pellets are introduced from the loader hopper 3 through the introduction section 20 into the drying hopper 2.

[0023] 1 and 2, a portion of the lower end side of the lower part of the drying hopper 2 has, for example, a cone shape or a square pyramid shape, and a discharge part 21 for resin pellets is provided at the lower end of the drying hopper 2. The resin pellets in the drying hopper 2 are discharged from the drying hopper 2 via the discharge part 21, for example by opening the solenoid valve 4, and are transported to the resin molding machine 6 through the transport pipe 5. The means for transporting the resin pellets from the drying hopper 2 to the resin molding machine 6 and stopping the transport are not particularly limited, and known means can be used.

[0024] 1 and 2, the boundary between the upper part and the lower part of the drying hopper 2 is tapered downward, and the storage space 22 in the drying hopper 2 is divided into a first area 22A on the lower side and a second area 22B on the upper side. At least one introduction part 23, 24 is provided in the lower part of the drying hopper 2 for introducing dry air into the drying hopper 2 for drying the resin pellets in the drying hopper 2. The tip of the lower second introduction part 24 preferably extends to the vicinity of the lower end of the drying hopper 2.

[0025] The dry air is introduced into the lower part of the drying hopper 2 through the upper first introduction section 23, and is introduced into the lowest part of the drying hopper 2 through the lower second introduction section 24. When the dry air comes into contact with the resin pellets in the drying hopper 2, the resin pellets are heated and the moisture content decreases. When the dry air rises inside the drying hopper 2, the resin pellets stored mainly in the lower part of the drying hopper 2 are dried. Since the dry air is introduced into the lowest part of the drying hopper 2 by the second introduction section 24, a decrease in the temperature of the resin pellets accumulated in the lower part of the drying hopper 2 is suppressed. The dry air removes moisture from the resin pellets, increasing its humidity, and the temperature decreases as the resin pellets remove heat from them.

[0026] As shown in Figures 1 and 2, an exhaust section 25 is provided at the top of the drying hopper 2, which discharges dry air used for drying the resin pellets to the outside of the drying hopper 2. In addition, an introduction section 26 is provided at a position below the exhaust section 25 at the top of the drying hopper 2, which introduces a portion of the dry air (exhaust air) discharged to the outside of the drying hopper 2 into the drying hopper 2. The exhaust air introduction section 26 is located above the dry air introduction sections 23, 24. The tip of the exhaust air introduction section 26 preferably extends to the boundary between the lower and upper parts of the drying hopper 2.

[0027] The shape and structure of the drying hopper 2 are not particularly limited, and any drying hopper having a conventionally known shape and structure can be used.

[0028] As shown in Fig. 1, the drying device 1 includes a generating section that generates dry air for drying the synthetic resin molding material in a drying hopper 2. In this embodiment, the generating section includes at least one (two in this embodiment) dehumidifier 8 that generates low dew point air, and a first heater 7A that heats the low dew point air to turn it into dry air. The dehumidifier 8 and the first heater 7A will be described later.

[0029] As shown in FIG. 1, the drying device 1 includes a dry air supply passage L1 for supplying dry air to a drying hopper 2. In this embodiment, one end of the dry air supply passage L1 is branched into two. One end of the dry air supply passage L1 is connected to a first introduction portion 23 of the drying hopper 2. The other end of the dry air supply passage L1 is connected to a second introduction portion 24 of the drying hopper 2. Dry air is supplied to the drying hopper 2 from the introduction portions 23, 24 through the dry air supply passage L1.

[0030] In this embodiment, the other end of the dry air supply path L1 branches into two. One end of the other end of the dry air supply path L1 is connected to an exhaust section 80 for low dew point air provided in one of the dehumidifiers 8. The other end of the dry air supply path L1 is connected to an exhaust section 80 for low dew point air provided in the other dehumidifier 8. The low dew point air generated in the dehumidifier 8 is supplied to the first heater 7A from the exhaust section 80 of the dehumidifier 8 through the dry air supply path L1.

[0031] In the dry air supply passage L1, a first heater 7A, a first filter device 9A, and a first blower 10A are provided between the drying hopper 2 and the dehumidifier 8, in that order from the closest to the drying hopper 2. The low dew point air discharged from the dehumidifier 8 passes through the first blower 10A, the first filter device 9A, and the first heater 7A in this order.

[0032] The first blower 10A draws in low dew point air from an inlet, compresses the low dew point air, and then discharges the compressed low dew point air from an outlet. The first filter device 9A removes foreign matter from the low dew point air. The first heater 7A heats the low dew point air to produce high temperature, low dew point dry air. The first heater 7A heats the low dew point air so that the temperature of the low dew point air is, for example, 110°C to 180°C, preferably 110°C to 140°C. The first heater 7A, the first filter device 9A, and the first blower 10A may be conventionally known.

[0033] 1, the drying device 1 includes an exhaust air discharge path L2 for discharging the dried air from the drying hopper 2 after drying the resin pellets in the drying hopper 2. The exhaust air discharge path L2 supplies the exhaust air from the drying hopper 2 to a dehumidifier 8.

[0034] One end of the exhaust air discharge passage L2 is connected to the exhaust section 25 at the top of the drying hopper 2. In this embodiment, the other end of the exhaust air discharge passage L2 branches into two. One end of the other end of the exhaust air discharge passage L2 is connected to an exhaust air introduction section 81 provided in one of the dehumidifiers 8. The other end of the exhaust air discharge passage L2 is connected to an exhaust air introduction section 81 provided in the other dehumidifier 8. The exhaust air is supplied to the dehumidifier 8 from the introduction section 81 through the exhaust air discharge passage L2.

[0035] In the exhaust air discharge path L2, a dust collector 11, a second blower 10B, and a cooler 12 are provided between the drying hopper 2 and the dehumidifier 8, in that order from the closest to the drying hopper 2. The exhaust air discharged from the drying hopper 2 passes through the dust collector 11, the second blower 10B, and the cooler 12 in this order.

[0036] The dust collector 11 removes foreign matter from the exhaust air flowing through the exhaust air discharge passage L2. The dust collector 11 may be, for example, a cyclone type dust collector, but is not limited to the cyclone type, and any conventionally known dust collector may be used.

[0037] The second fan 10B draws in exhaust air from an inlet, compresses the exhaust air, and then discharges the compressed exhaust air from an outlet. A conventionally known fan can be used as the second fan 10B.

[0038] The cooler 12 cools the exhaust air supplied to the dehumidifier 8 to lower the temperature of the exhaust air. The cooler 12 cools the exhaust air so that the temperature of the exhaust air becomes, for example, about 40°C. If the exhaust air discharged from the drying hopper 2 is supplied to the dehumidifier 8 at a high temperature, the efficiency of dehumidifying the exhaust air in the dehumidifier 8 decreases. Therefore, by supplying the exhaust air cooled by the cooler 12 to the dehumidifier 8, the efficiency of dehumidifying the exhaust air in the dehumidifier 8 can be improved. As a result, low dew point air can be efficiently generated in the dehumidifier 8.

[0039] The cooler 12 is preferably an air-cooled heat exchanger. Exhaust air is introduced into the cooler 12 from an exhaust air inlet 120, and outside air is introduced from an outside air inlet 122, and the cooler 12 cools the exhaust air by heat exchange with the outside air. The cooled exhaust air is discharged from an exhaust air exhaust section 121 and supplied to the dehumidifier 8. The outside air is heated by removing thermal energy from the exhaust air through heat exchange with the exhaust air. The outside air heated by heat exchange with the exhaust air is discharged from an outside air exhaust section 123, and a part of the discharged outside air is supplied to the dehumidifier 8 as regenerated gas.

[0040] The shape and structure of the cooler 12 are not particularly limited as long as it is an air-cooled heat exchanger, and any conventionally known cooler can be used.

[0041] 1, the drying apparatus 1 includes an outside air supply passage L3 for supplying outside air to the cooler 12. A second filter device 9B and a third blower 10C are provided in the outside air supply passage L3 upstream of the cooler 12. The outside air passes through the second filter device 9B and the third blower 10C in this order.

[0042] The third blower 10C draws in outside air from the intake port, compresses the outside air, and then discharges the compressed outside air from the exhaust port. The second filter device 9B removes foreign matter from the outside air flowing through the outside air supply passage L3. The second filter device 9B and the third blower 10C may be conventionally known.

[0043] A temperature sensor 13 is provided in exhaust air discharge path L2 between the cooler 12 and the dehumidifier 8 (downstream of the cooler 12). The temperature sensor 13 measures the temperature of the exhaust air that is supplied to the dehumidifier 8 after being cooled by the cooler 12. In this embodiment, the temperature of the exhaust air measured by the temperature sensor 13 is monitored by a control device 14. That is, the temperature sensor 13 converts the measured temperature into an electric signal and outputs it to the control device 14.

[0044] The control device 14 constantly monitors the temperature of the exhaust air supplied to the dehumidifier 8, and controls the volume of outside air supplied from the third blower 10C to the cooler 12 (the volume of air blown by the third blower 10C) so that the temperature of the exhaust air is a constant temperature, for example, 40°C. The control device 14 controls the number of rotations (rotation speed) of a motor built into the third blower 10C using an inverter, for example, according to the temperature of the exhaust air. As a result, outside air with a volume according to the temperature of the exhaust air is supplied to the cooler 12, and the temperature of the exhaust air supplied to the dehumidifier 8 is adjusted to a constant temperature. The volume of air blown by the third blower 10C may be controlled by adjusting a damper.

[0045] In this embodiment, the drying device 1 includes a temperature indicator controller (TIC) as the control device 14. The temperature indicator controller compares the electrical signal output from the temperature sensor 13 with a target value, and performs calculations according to the deviation to control the third blower 10C. The control device 14 may be configured with a general-purpose computer.

[0046] As shown in FIG. 1, the drying device 1 includes a dehumidifier 8. The dehumidifier 8 generates low dew point air by dehumidifying exhaust air. The dehumidifier 8 contains an adsorbent. Exhaust air is introduced into the dehumidifier 8 from the exhaust air discharge passage L2 through an introduction part 81. In the dehumidifier 8, the exhaust air comes into contact with the adsorbent, and moisture contained in the exhaust air is adsorbed by the adsorbent, thereby removing the moisture from the exhaust air. In this way, the exhaust air is dehumidified in the dehumidifier 8 to generate low dew point air.

[0047] The low dew point air generated in the dehumidifier 8 is discharged from the dehumidifier 8 through the exhaust section 80 and is supplied to the first heater 7A through the dry air supply passage L1. Then, in the first heater 7A, the low dew point air is heated to become high-temperature, low dew point dry air, and the dry air is supplied to the drying hopper 2 through the dry air supply passage L1. The adsorbent is not particularly limited as long as it can adsorb moisture from gas, and examples of the adsorbent include silica gel, zeolite, activated carbon, and metal organic frameworks (MOFs).

[0048] Further, the dehumidifier 8 is introduced with regenerated gas from the regenerated gas supply passage L4 through the introduction section 83. The regenerated gas comes into contact with the adsorbent in the dehumidifier 8, and the moisture adsorbed by the adsorbent is desorbed, thereby removing the moisture from the adsorbent. This regenerates the adsorbent in the dehumidifier 8. The regenerated gas is not particularly limited, but is high-temperature air at, for example, 200°C to 230°C. The regenerated gas after the adsorbent is regenerated in the dehumidifier 8 (referred to as "regenerated gas" in this disclosure) is discharged from the dehumidifier 8 through the exhaust section 82.

[0049] The shape and structure of the dehumidifier 8 are not particularly limited as long as it is configured to remove moisture contained in the exhaust air from the exhaust air by adsorption with an adsorbent to generate air with a low dew point, and to remove the moisture adsorbed by the adsorbent from the adsorbent by desorption with a regeneration gas to regenerate the adsorbent.

[0050] For example, the dehumidifier 8 is a rotor rotation type continuous dehumidifier. This type of dehumidifier 8 includes a cylindrical adsorption rotor that can rotate around a rotation axis, and the adsorption rotor includes an adsorption element, for example, of a honeycomb structure. An adsorbent is supported on the adsorption element. The adsorption rotor is divided into an adsorption zone and a desorption zone along the circumferential direction around the rotation axis, and the adsorption element moves alternately between the adsorption zone and the desorption zone as the adsorption rotor rotates.

[0051] The exhaust air is supplied to the adsorption zone of the adsorption rotor, and moisture contained in the exhaust air is adsorbed by the adsorbent as it passes through the adsorption element located in the adsorption zone, thereby dehumidifying the exhaust air. The regeneration gas is supplied to the desorption zone of the adsorption rotor, and desorbs moisture from the adsorbent as it passes through the adsorption element located in the desorption zone, thereby regenerating the adsorbent.

[0052] The dehumidifier 8 is not limited to a rotor-rotating type continuous dehumidifier, and other conventionally known dehumidifiers may be used.

[0053] 1, the drying device 1 includes a regeneration gas supply passage L4 for supplying a regeneration gas for regenerating an adsorbent in the dehumidifier 8 to the dehumidifier 8. As the regeneration gas, outside air whose temperature has been increased by heat exchange with exhaust air in the cooler 12 is used. The regeneration gas supply passage L4 supplies the outside air discharged from the cooler 12 to the dehumidifier 8.

[0054] One end of the regeneration gas supply line L4 is connected to the outside air supply line L3 downstream of the cooler 12. In this embodiment, the other end of the regeneration gas supply line L4 branches into two. One end of the other end of the regeneration gas supply line L4 is connected to a regeneration gas inlet 83 provided in one of the dehumidifiers 8. The other end of the other end of the regeneration gas supply line L4 is connected to a regeneration gas inlet 83 provided in the other dehumidifier 8. The outside air discharged from the cooler 12 is supplied as regeneration gas from the regeneration gas supply line L4 through the inlet 83 to the dehumidifier 8.

[0055] In the regeneration gas supply passage L4, a preheater 15 and a third heater 7C are provided between the cooler 12 and the dehumidifier 8, in that order from the cooler 12. The outside air discharged from the cooler 12 is introduced into the dehumidifier 8 via the preheater 15 and the third heater 7C in this order.

[0056] The third heater 7C heats the outside air discharged from the cooler 12 (the outside air supplied to the dehumidifier 8 as regenerated gas) to increase the temperature of the outside air. The third heater 7C heats the outside air to increase the temperature of the outside air to, for example, 200° C. to 230° C. As the third heater 7C, a conventionally known heater can be used.

[0057] Preheater 15 preheats the outside air discharged from cooler 12 (outside air supplied to dehumidifier 8 as regenerated gas) to increase the temperature of the outside air. The temperature of the outside air discharged from cooler 12 is, for example, 51°C to 56°C, and by preheating the outside air with preheater 15, the amount of thermal energy added to the outside air in third heater 7C can be reduced.

[0058] The preheater 15 is preferably an air-cooled heat exchanger. The preheater 15 is introduced with outside air discharged from the cooler 12 through the regenerated gas inlet 150 (outside air introduced into the dehumidifier 8 as regenerated gas) and with the regenerated gas discharged from the dehumidifier 8 through the regenerated gas inlet 152. The regenerated gas is a regenerated gas after the adsorbent is regenerated in the dehumidifier 8, and is at a high temperature (for example, about 160°C). Therefore, the preheater 15 preheats the outside air discharged from the cooler 12 by heat exchange with the high-temperature regenerated gas. The heated outside air is heated, for example, to 140°C to 150°C, discharged from the regenerated gas exhaust section 151, and further heated by the third heater 7C.

[0059] The regenerated gas is cooled to, for example, 55° C. to 67° C. by heat exchange with the outside air discharged from the cooler 12 and is discharged to the outside of the system from the exhaust part 153 for the regenerated gas.

[0060] The preheater 15 is not particularly limited in shape or structure as long as it is an air-cooled heat exchanger, and any conventionally known preheater can be used.

[0061] 1, the drying device 1 includes a regenerated gas discharge passage L5 for discharging the regenerated gas from the dehumidifier 8. The regenerated gas discharge passage L5 transfers the regenerated gas discharged from the dehumidifier 8 to the preheater 15.

[0062] One end of the regenerated gas flow passage L5 is connected to the preheater 15. In this embodiment, the other end of the regenerated gas flow passage L5 branches into two. One end of the other end of the regenerated gas flow passage L5 is connected to an exhaust section 82 for regenerated gas provided in one of the dehumidifiers 8. The other end of the regenerated gas flow passage L5 is connected to an exhaust section 82 for regenerated gas provided in the other dehumidifier 8. The regenerated gas flows through the regenerated gas flow passage L5 from the dehumidifier 8 through the exhaust section 82.

[0063] The regenerated gas flow path L5 is provided with a fourth blower 10D and a preheater 15 in the order of proximity to the dehumidifier 8. The regenerated gas discharged from the dehumidifier 8 passes through the fourth blower 10D and the preheater 15 in this order.

[0064] The fourth blower 10D draws in the regenerated gas from the suction port, compresses the regenerated gas, and then discharges the compressed regenerated gas from the discharge port. The regenerated gas discharged from the fourth blower 10D is supplied to the preheater 15, and as described above, is used to preheat the outside air discharged from the cooler 12. A conventionally known blower can be used as the fourth blower 10D.

[0065] A branch passage L6 is connected to the regeneration gas discharge L5 at a position between the fourth blower 10D and the preheater 15. The branch passage L6 is connected to the regeneration gas supply passage L4. The connection position of the branch passage L6 in the regeneration gas supply passage L4 is a position between the preheater 15 and the third heater 7C.

[0066] The branch passage L6 mixes a portion of the regenerated gas discharged from the dehumidifier 8 with the outside air discharged from the cooler 12 (the outside air supplied to the dehumidifier 8 as the regenerated gas). Since the regenerated gas has a high temperature (for example, about 160°C), the temperature of the outside air increases when the regenerated gas is mixed with the outside air discharged from the cooler 12. This makes it possible to reduce the amount of thermal energy added to the outside air in the third heater 7C.

[0067] As shown in FIG. 1, the drying device 1 includes an exhaust air supply passage L7 for supplying a portion of the exhaust air discharged from the drying hopper 2 and flowing through the exhaust air discharge passage L2 to the drying hopper 2. One end of the exhaust air supply passage L7 is connected to the exhaust air flow passage L2 downstream of the dust collector 11, and the other end of the exhaust air supply passage L7 is connected to an introduction section 26 at the top of the drying hopper 2. The exhaust air supply passage L7 supplies the exhaust air discharged from the drying hopper 2 as a preheated gas from the exhaust air discharge passage L2 to the drying hopper 2. The preheated gas is introduced from the exhaust air supply passage L7 through the introduction section 26 to the top of the drying hopper 2.

[0068] The temperature of the undried resin pellets supplied to the drying hopper 2 is, for example, 20°C to 25°C, and the moisture content is, for example, about 3000 ppm. The exhaust air discharged from the drying hopper 2 has a lower temperature and a higher humidity than the dry air before being introduced into the drying hopper 2 because it has been used to dry the resin pellets in the drying hopper 2, but has a relatively high temperature and low humidity. Therefore, by introducing the exhaust air discharged from the drying hopper 2 into the upper part of the drying hopper 2, the resin pellets can be preheated in the upper part of the drying hopper 2 before the resin pellets are fully dried in the lower part of the drying hopper 2 with the dry air, and the moisture content of the resin pellets can be reduced in advance to, for example, about 150 ppm by initially drying the resin pellets. This makes it possible to reduce the amount of heat energy added to the resin pellets in order to dry the resin pellets in the lower part of the drying hopper 2 until the moisture content is, for example, about 50 ppm or less. Therefore, a large amount of heat energy is not required to dry the resin pellets, and energy saving can be achieved.

[0069] The exhaust air supply passage L7 is provided with a second heater 7B, a third filter device 9C, and a fifth blower 10E in the order of proximity to the drying hopper 2. The exhaust air discharged from the drying hopper 2 passes through the exhaust air discharge passage L2, the fifth blower 10E, the third filter device 9C, and the second heater 7B in this order.

[0070] The fifth fan 10E draws in low dew point air from the intake port, compresses the exhaust air, and then discharges the compressed exhaust air from the exhaust port. The third filter device 9C removes foreign matter from the exhaust air. The second heater 7B heats the exhaust air. The second heater 7B, the third filter device 9C, and the fifth fan 10E may be conventionally known.

[0071] In this embodiment, a portion of the exhaust air discharged from the drying hopper 2 is heated by the second heater 7B and then returned to the drying hopper 2. However, a portion of the exhaust air discharged from the drying hopper 2 does not necessarily have to be heated by the second heater 7B and then returned to the drying hopper 2, and may be returned to the drying hopper 2 without being heated.

[0072] After preheating the resin pellets in the drying hopper 2, the exhaust air is discharged from the drying hopper 2 through the exhaust section 25 at the top of the drying hopper 2.

[0073] In the drying device 1 shown in FIG. 1 described above, the synthetic resin molding material such as resin pellets is heated by high-temperature and low-dew-point dry air in the lower part of the drying hopper 2, so that moisture is removed from the synthetic resin molding material and the synthetic resin molding material is dried. The dried synthetic resin molding material in the lower part of the drying hopper 2 is discharged from the drying hopper 2 through the discharge part 21 at the lower end of the drying hopper 2 and transported to the resin molding machine 6, and the synthetic resin molding material is replenished from the upper part of the drying hopper 2 to the lower part of the drying hopper 2. The dried synthetic resin molding material in the lower part of the drying hopper 2 is discharged from the drying hopper 2 in a high temperature state and transported to the resin molding machine 6 because the temperature drop is suppressed by the dry air at the bottom of the drying hopper 2 by the second introduction part 24. Therefore, according to the drying device 1 of this embodiment, the synthetic resin molding material from which moisture has been removed can be supplied to the resin molding machine 6.

[0074] In addition, in the drying device 1 shown in FIG. 1, a portion of the exhaust air discharged from the drying hopper 2 after drying the synthetic resin molding material is supplied to the dehumidifier 8 via the exhaust air discharge path L2, and after being dehumidified in the dehumidifier 8, is supplied to the drying hopper 2 and is used again to dry the synthetic resin molding material, while a portion of the exhaust air discharged from the drying hopper 2 is supplied to the upper part of the drying hopper 2 via the exhaust air supply path L7.

[0075] The exhaust air supplied to the drying hopper 2, together with the dry air rising from the lower part of the drying hopper 2, preheats and initially dries the undried synthetic resin molding material accumulated in the upper part of the drying hopper 2. For this reason, the synthetic resin molding material whose temperature has increased and whose moisture content has decreased due to preheating and initial drying is supplied from the upper part of the drying hopper 2 to the lower part of the drying hopper 2.

[0076] In this way, according to the drying device 1 shown in Fig. 1, by returning a portion of the exhaust air discharged from the drying hopper 2 to the upper part of the drying hopper 2, the thermal energy of the exhaust air is effectively utilized for preheating and initial drying of the synthetic resin molding material without being wasted. As a result, the synthetic resin molding material is heated and dried in the lower part of the drying hopper 2, but the amount of thermal energy required to dry the synthetic resin molding material can be reduced. Therefore, a large amount of thermal energy is not required to dry the synthetic resin molding material, and energy can be saved.

[0077] 1, a part of the exhaust air discharged from the drying hopper 2 is returned to the upper part of the drying hopper 2, so that the thermal load when the exhaust air is cooled, dehumidified, heated, etc. in the cooler 12, the dehumidifier 8, the first heater 7A, etc. to generate dry air can be reduced. Therefore, the thermal energy required to generate dry air can be reduced, and energy can be saved.

[0078] 1, even when the synthetic resin molding material is dried in a low temperature range (e.g., 110°C to 140°C) that is unlikely to cause changes in the physical properties of the synthetic resin molding material in the lower part of the drying hopper 2, the synthetic resin molding material whose temperature has increased and whose moisture content has decreased due to preheating and initial drying is supplied from the upper part of the drying hopper 2 to the lower part of the drying hopper 2, so that the time required for drying the synthetic resin molding material can be shortened compared to the conventional method. Thus, according to the drying device 1 of this embodiment, even when the synthetic resin molding material is dried in a low temperature range (e.g., 110°C to 140°C), the drying can be completed in a short time, and even if some abnormality occurs in the drying device 1 during the drying of the synthetic resin molding material and the synthetic resin molding material continues to remain in the drying hopper 2, the physical properties of the synthetic resin molding material are unlikely to change.

[0079] 1, the drying device 1 has a first heater 7A for heating the dry air (low dew point air) supplied to the bottom of the drying hopper 2 and a second heater 7B for heating the exhaust air supplied to the top of the drying hopper 2, so that the temperatures of the dry air and the exhaust air can be set independently. This makes it possible to prevent the synthetic resin molding material from being excessively dried in the bottom of the drying hopper 2, and also makes it possible to easily obtain a dried synthetic resin molding material at a temperature that matches the molding conditions of the resin molding machine 6.

[0080] Although the embodiment of the drying device of the present disclosure has been described above, the drying device of the present disclosure is not limited to the embodiment shown in Fig. 1 described above, and various modifications are possible without departing from the spirit of the present disclosure. For example, the following modifications are possible. In addition, the gist of the following modifications can be combined as appropriate.

[0081] For example, in the above-described embodiment, the drying apparatus 1 includes two dehumidifiers 8. As a modified example, the drying apparatus 1 may include one dehumidifier 8, or three or more dehumidifiers 8.

[0082] In the above-described embodiment, the drying apparatus 1 includes the second filter device 9B, and foreign matter is removed from the outside air by the second filter device 9B before the outside air is introduced into the cooler 12. As a modified example, the drying apparatus 1 does not need to include the second filter device 9B.

[0083] In the above-described embodiment, the drying device 1 includes a circulation flow path L6, and a part of the regenerated gas discharged from the dehumidifier 8 is mixed with the outside air discharged from the cooler 12 (the outside air supplied to the dehumidifier 8 as the regenerated gas). As a modified example, the drying device 1 does not need to include the circulation flow path L6, and all of the regenerated gas discharged from the dehumidifier 8 may be introduced into the preheater 15 and then exhausted to the outside of the system.

[0084] In the above-described embodiment, the drying device 1 includes the preheater 15, and the outside air discharged from the cooler 12 (outside air supplied to the dehumidifier 8 as regenerated gas) is preheated by heat exchange with the regenerated gas discharged from the dehumidifier 8 and then supplied to the third heater 7C. As a modified example, the drying device 1 does not need to include the preheater 15, and the outside air discharged from the cooler 13 (outside air supplied to the dehumidifier 8 as regenerated gas) may be supplied to the third heater 7C without being preheated. In this modified example, a part of the regenerated gas discharged from the dehumidifier 8 may be mixed with the outside air discharged from the cooler 12 (outside air supplied to the dehumidifier 8 as regenerated gas) via the circulation flow path L6, or all of it may be exhausted to the outside of the system.

[0085] In the above-described embodiment, part of the outside air discharged from the cooler 12 is discharged outside the system, and part of the outside air is supplied as a regenerated gas to the dehumidifier 8. As a modified example, part of the outside air discharged from the cooler 12 may be supplied as a regenerated gas to the dehumidifier 8, and part of the outside air may be supplied as a preheated gas to the storage hopper 16 as shown in FIG.

[0086] The drying device 1 shown in FIG. 3 includes a storage hopper 16 for temporarily storing resin pellets. The storage hopper 16 is disposed above the drying hopper 2. The storage hopper 16 has an internal space capable of storing resin pellets supplied from a raw material tank through a supply pipe 162. The resin pellets supplied from the raw material tank are undried resin pellets. The resin pellets are supplied to the storage hopper 16 from a supply unit provided at the upper part of the storage hopper 16. The lower part of the storage hopper 16 has, for example, a conical or quadrangular pyramid shape, and a resin pellet discharge unit 164 is provided at the lower end of the storage hopper 16. The resin pellets in the storage hopper 16 are supplied to the drying hopper 2 from the discharge unit 164 by, for example, opening an electromagnetic valve 163.

[0087] The resin pellets are preheated while being stored in the storage hopper 16. The storage hopper 16 is provided with an introduction section 160 that introduces a preheated gas for preheating the resin pellets in the storage hopper 16 into the storage hopper 16. The storage hopper 16 is also provided with a discharge section 161 at a position above the introduction section 160 that discharges the preheated gas from the storage hopper 16 after preheating the resin pellets in the storage hopper 16.

[0088] For the preheated gas, outside air heated by heat exchange with exhaust air in the cooler 12 is used. At least a part of the outside air discharged from the cooler 12 is supplied to the storage hopper 16 through a preheated gas flow path L8. One end of the preheated gas flow path L8 is connected to the outside air flow path L3 downstream of the cooler 12, and the other end of the preheated gas flow path L8 is connected to the introduction part 160 of the storage hopper 16. The resin pellets in the storage hopper 16 are supplied to the drying hopper 2 in a state in which they have been preheated by the preheated gas and their temperature has increased.

[0089] In this way, according to the drying device 1 shown in Fig. 3, by supplying the outside air discharged from the cooler 12 to the storage hopper 16 as preheating gas, the thermal energy recovered from the exhaust air as the exhaust air is cooled in the cooler 12 is not wasted but is effectively utilized for preheating synthetic resin molding material such as resin pellets. As a result, the synthetic resin molding material is heated and dried in the drying hopper 2, but the amount of thermal energy required to dry the synthetic resin molding material can be reduced. Therefore, a large amount of thermal energy is not required to dry the synthetic resin molding material, and energy can be saved.

[0090] In the drying apparatus 1 shown in FIG. 3, all of the outside air discharged from the cooler 12 may be supplied to the storage hopper 16 as a preheated gas, and outside air other than the outside air discharged from the cooler 12 may be introduced into the dehumidifier 8 as a regeneration gas.

[0091] As another modified example, the drying device 1 shown in FIG. 4 may be provided with a heat exchanger 17 that exchanges heat between the low dew point air supplied from the dehumidifier 8 and the exhaust air discharged from the drying hopper 2.

[0092] The temperature of the low dew point air supplied from the dehumidifier 8 is, for example, about 55°C, and the low dew point air is heated in the first heater 7A and then supplied to the drying hopper 2. Since the temperature of the exhaust air discharged from the drying hopper 2 is relatively high, the low dew point air supplied from the dehumidifier 8 can be heated by heat exchange with the exhaust air discharged from the drying hopper 2 in the heat exchanger 17, so that the low dew point air can be supplied to the first heater 7A in an elevated temperature state.

[0093] The low dew point air is heated to, for example, about 60°C to 70°C by absorbing thermal energy through heat exchange with the exhaust air. As a result, in the drying device 1 shown in Fig. 4, the amount of thermal energy added to the low dew point air in the first heater 7A can be reduced, and the thermal energy of the exhaust air discharged from the drying hopper 2 can be effectively utilized for generating dried air without being wasted. Therefore, the drying device 1 shown in Fig. 4 can effectively suppress energy loss and improve energy efficiency.

[0094] The exhaust air supplied to the heat exchanger 17 may be the exhaust air before passing through the dust collector 11, but is preferably the exhaust air after passing through the dust collector 11. The low dew point air supplied to the heat exchanger 17 may be the low dew point air before passing through the first filter device 9A, but is preferably the low dew point air after passing through the first filter device 9A. [Explanation of symbols]

[0095] 1 Drying device 2 Drying hopper 7A First heater (generation section) 7B Second heater 8 Dehumidification device (generation part) L1 Dry air supply line L2 Exhaust air outlet L7 Exhaust air supply passage

Claims

1. A drying hopper configured to accommodate a synthetic resin molding material introduced from an upper portion and to discharge the synthetic resin material from a lower portion; A generating unit that generates dry air for drying the synthetic resin molding material in the drying hopper; a dry air supply passage for supplying the dry air to the drying hopper; an exhaust air discharge passage for discharging dry air used for drying the synthetic resin molding material in the drying hopper from the drying hopper; an exhaust air supply passage for supplying a portion of the exhaust air flowing through the exhaust air flow path to the drying hopper; Equipped with The drying hopper is configured so that the dry air from the dry air supply passage is introduced to a lower side thereof, and the exhaust air from the exhaust air supply passage is introduced to an upper side thereof.

2. The generating unit includes a dehumidifier that generates low dew point air, and a first heater that heats the low dew point air to generate the dry air, The drying device according to claim 1 , further comprising a second heater provided in the exhaust air discharge passage for heating the exhaust air supplied to the drying hopper.

3. 2. The drying apparatus according to claim 1, wherein the temperature of the drying air supplied to the drying hopper is 120°C or higher and 130°C or lower.

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